Development of a technological process for manufacturing a part. Course work
A typical TP is developed on the basis of an analysis of the set of existing and possible TP for typical representatives of product groups. He must be rational in specific working conditions and have the unity of the content and consistency of most of the TO for a group of products that have common design features.
The design of technological processes depends on the type of production.
For simple details detailed routing technical processes are being developed, indicating the content of operations and transitions, as well as the dimensions to be maintained. Typical manufacturing processes are usually equipped with universal machine tools and standard tooling. Universal and group fixtures are used.
In large-scale production, billets are widely used as billets, castings, hammer forging, welded structures and other types of billets, the use of which is economically feasible.
The technological process must ensure the manufacture of parts of a given quality and volume of output, meet the requirements of high processing productivity, the lowest production cost, safety and ease of working conditions.
The properties of parts are formed in stages - from operation to operation, since for each processing method (turning, grinding, etc.) there are possibilities for correcting the initial errors of the workpiece and obtaining the required accuracy and quality of the processed surfaces. This is due primarily to the physical nature of the way of processing.
When designing a technological operation, it is necessary to strive to reduce its labor intensity. The processing performance depends on the cutting conditions, the number of transitions and working strokes, the sequence of their execution.
The number and sequence of technological transitions depend on the type of blanks and the accuracy requirements for the finished part. The alignment of transitions is determined by the design of the part, the possibilities of the location of the cutting tools on the machine and the rigidity of the workpiece. Transitions that meet strict requirements for accuracy and surface roughness, it is sometimes advisable to separate into a separate operation, using a single-tool sequential processing.
The shape of the "cover" part is correct geometric, it is a body of revolution. The value of surface roughness corresponds to the accuracy classes of their dimensions and the methods of processing these surfaces. To process a part, it is enough to use turning, boring, broaching, grinding and hobbing operations.
DEVELOPMENT OF ROUTING TECHNOLOGY
When developing a technological process, the following principles should be followed:
when processing workpieces obtained by casting, untreated surfaces can be used as bases for the first operation;
when processing blanks of all surfaces, it is advisable to use surfaces with the smallest allowances as technological bases for the first operation;
first of all, those surfaces that are basic in further processing should be processed;
at the beginning of the technological process, those operations should be carried out in which there is a high probability of obtaining a marriage due to a defect.
The technological process is recorded operationally, with a listing of all transitions.
A 005 Turning operation
B Lathe with CNC 16K30F3
O
2. Cut the butt to size 24 ± 0.3
3. Cut to size w90.6 +0.2
4. Bore to size w 66.8 +0.2
4. Remove chamfer 1x45
5. Remove the part.
T
A 010 Turning operation
B Lathe with CNC 16K30F3
O 1. Install the part into the chuck.
2. Trim the butt to size 22
3. Cut to size Ш120
4. Bore to size 75.6 +0.2
6. Remove the part.
T Self-centering chuck, scoring cutter T15K6, straight through cutter T15K6, ruler, vernier caliper.
A 015 Radial drilling
B Radial drilling 2А534
O 1.Install part
2. Drill hole Ш9 ± 0.2
3. Counterbore hole Ш14
4. Remove the part.
T Drill R6M5, counterbore R6M5 vernier caliper.
A 020 Operation horizontal milling
B Horizontal milling 6R83G
O 1. Install part
2. Mill flats to size 109.
3. Remove the parts.
T Disk cutter T15K6, snag caliper, roughness sample.
A 025 Operation circular grinding
B Circular grinding machine 3B161
O 1. Install the part.
2. Grind the part in size W90
3. Remove the part.
A 030 Internal grinding operation
B
O 1.Install the part
2. Grind the hole to size Ш66Н7 +0.03 with roughness Ra0.8.
3. Remove the part.
T
A 035 Internal grinding operation
B... Internal grinding machine 3K2228A
O 1.Install the part
2. Grind the hole in size Ш75Н7 with roughness Ra0.8.
3. Remove the part.
T Mandrel, grinding wheel, internal gauge, roughness sample.
Operation 040 The control is final.
CALCULATION OF PROCESSING MODES
The main cutting elements in turning are: cutting speed V, feed S and depth of cut t.
Cutting conditions when processing a part will be calculated by the calculation method.
a) When turning, the cutting speed is calculated by the formula:
where T is the average value of durability, min;
(with one-tool processing T = 60 min)
t is the depth of cut;
S - feed;
C v = 56; m = 0.125; y = 0.66; x = 0.25.
We take the value of the flow rate S from point 11-14.
The value of the coefficients C and exponents is chosen from point 8
Coefficient K is determined by the formula
where K m - coefficient taking into account the influence of the workpiece material;
K p - coefficient taking into account the state of the surface of the workpiece;
K u - coefficient taking into account the material of the tool;
The value of the coefficients K m, K u and K p is selected from points 1-6.
K m = 0.8; K u = 1; K p = 0.8.
Determine the number of revolutions of the machine spindle.
where V is the cutting speed;
D is the diameter of the treated surface;
Determine the main technological time
where l р.х. - length of the working stroke of the cutter, mm;
i - number of passes, pcs.
b) Cutting speed when milling:
v = C v K v D q / (T m t x s y B p Z p);
where B p and Z p are reference coefficients.
For cutting, slotting:
K Mv = 0.80; K Pv = 0.85; K And v = 1.68.
The results of calculations according to the above formulas are entered into the set of documentation for the technological process in the corresponding columns of the route-operational map.
NORMALIZATION OF TECHNICAL OPERATIONS
Technical norms of time in conditions of mass and serial production are established by the calculation and analytical method. In repetitive production, the standard of piece-costing time is determined Tsh-k by the following formula:
where T p-z - preparatory and final time, min;
n- the number of parts in the batch;
Tsht- rate of piece time, min.
The piece time rate can be determined by the formula:
where T about - main time, min;
Tv- auxiliary time, min .;
Tob.from- time for maintenance of the workplace, for rest and personal needs min.
The auxiliary time is determined by the formula:
where T us - time for installation and removal of the part, min;
Tzo- time for fastening and unfastening a part, min .;
Stupid- time for control receptions, min .;
Teese- time to measure a part, min.
Time for servicing the workplace, for rest and personal needs is determined by the formula:
Operating time T op is determined by the formula:
Next, we will make a calculation for all technological operations, using the above formulas, the results will be entered into the documentation set for the technological process in the corresponding columns of the route-operational map.
Since 1975, we have been implementing one system technological preparation of production (ESTPP), the main purpose of which is to establish a system of organization and management of technological preparation of production, regulated by state standards.
According to GOST 14.004-83, technological preparation of production is understood as a set of measures that ensure the technological readiness of production (the availability of complete sets of design and technological documentation and technological equipment at the enterprise) for the implementation of a given volume of production with established technical and economic indicators.
The basis of the ESTPP is the development technological processes.
The level of detail in the description of technological processes is indicated in GOST Z.1109-82,
1. Route description of the technological process is an abbreviated description of all technological operations in the route map in the sequence of their execution without indicating transitions and technological modes. Such a description of technological processes is carried out in a single, and for irrelevant parts and in small-scale production.
2. The operational description of the technological process is Full description all technological operations in the sequence of their execution, indicating the transitions and technological modes. Operational technological processes are used in large-scale and mass production.
3. Route-operational description of a technological process is a route description of the entire technological process and an operational description of some operations, as a rule, forming the quality of the product. Such technological processes are used in small-scale and medium-scale production.
According to the organization of production, technological processes are divided into:
1) a typical technological process is a technological process of manufacturing a group of products with common design and technological characteristics;
2) a group technological process is a technological process of manufacturing a troupe of products with different constructive, but common technological characteristics;
3) a single technological process is a technological process of manufacturing or repairing a product of the same name, standard size and design.
The initial data for the design of technological processes for processing blanks are:
1) a working drawing that defines the material, design forms and dimensions of the part;
2) technical conditions for the manufacture of parts, characterizing the dimensional accuracy and quality of surfaces, as well as special requirements(hardness, structure, heat treatment, balancing, weight adjustment, etc.);
3) annual release program.
When designing technological processes for existing industries, in addition, it is necessary to have information about the availability of equipment and its loading, measuring and cutting tools, technological equipment, vacant areas and other production conditions. In addition, the design uses: reference and regulatory materials; equipment catalogs and passports; gadget albums; GOSTs and normals for cutting and measuring tools, technological equipment; standards for accuracy, roughness, calculation of allowances, cutting conditions and technical standardization; tariff and qualification reference books and other auxiliary materials.
The development of technological processes is based on two basic principles: technical and economic. In accordance with technical principle the designed technological process must fully ensure the fulfillment of all the requirements of the working drawing and technical conditions for the manufacture of a given part.
In accordance with the economic principle, the manufacture of the product must be carried out with minimal cost labor and production costs. The technological process of manufacturing products should be carried out with the fullest possible use technical capabilities means of production, with the least investment of time and cost of goods.
To establish the possibility of ensuring the required accuracy, a dimensional analysis of the technological process is carried out.
Building a chain starts with the task at hand. The initial or closing link of the technological dimensional chain can be: 1) a drawing dimension with a regulated tolerance, which is not directly maintained during processing; 2) the operating allowance for processing, based on the minimum value of which it is necessary to establish the operating dimensions for all stages of data processing of interconnected surfaces. The constituent links involved in solving the problem are sequentially attached to it, until the chain becomes closed.
In fig. 6.12 shows examples of constructing dimensional chains based on different conditions... Processing of end surfaces 1 - 5 (fig. 6.12, a) is performed in four operations. Withstood at the same time linear dimensions shown in operating sketches. Dimension chains are generated for each operational sketch.
In the first milling-centering operation, the ends are machined 1 and 5 (Fig. 6.12, b), keeping the dimensions B 1 and B 2. Since the technological dimension B 2 coincides with the design dimension A 4, there is no need to recalculate it. Butt 2 in the future it is necessary to process, therefore, the technological size B 1 is not design, and therefore, it needs to be recalculated. For this, a dimensional chain is drawn up for the first operation (Fig. 6.12, c). The closing link in this dimensional chain is machining allowance Z 1.
Rice. 6.12 Dimensional analysis of the technological process
In the second turning operation, the ends are processed 3 and 4 (fig. 6.12, v) and the dimensions are maintained V ( and IN 2 . Surface 3 is a tuning base for getting the size IN 2 . Since in what follows it is assumed finishing butts 3 and 4, then the technological dimensions and IN 2 are not design, therefore, they need to be recalculated. For this, two dimensional chains are made up (Fig. 6.12, h). When sizing V 1 and IN 2 the closing links are allowances, respectively Z 2 and Z 3.
In the third turning operation, the butt is machined 2 (fig. 6.12, G) and the size G is maintained. This size is not a design one, therefore, to determine it, a dimensional chain is built (Fig. 6.12, and). The closing dimension in this chain is A 1.
In the fourth cylindrical grinding operation, the ends are finally processed 3 and 4 (Fig. 6.12, e). Surface 3 on this operation is a tuning base for obtaining a technological size D 2, which is the same as the design size A 3, therefore, there is no need to recalculate it. To determine the technological size D 1, we compose a dimensional chain (Figure 6.12, k), the closing link in which is the size A 2.
The combination of the constructed operational dimensional chains (Fig. 6.12, e) allows for dimensional analysis of the entire technological process.
In accordance with the ESTPP, the development of technological processes for the manufacture of machine parts for a new production is carried out in the following sequence.
1. Establish the type of production with the calculation of tact or batch size.
2. Pre-select the possible methods of obtaining blanks, make their technical and economic comparison and choose the best option.
3. Make up several possible options route technologies, make their technical and economic comparison and choose the best option.
4. To develop an operating technology for manufacturing a part:
a) a plan for surface treatment to achieve the required accuracy and roughness;
b) selection of equipment;
c) choice of basing schemes;
d) calculation and assignment of allowances;
e) dimensional analysis of the technological process;
f) the choice of the tool, its material and technological equipment, if necessary, their design;
g) calculation and assignment of processing modes;
h) the choice of measuring instruments, if necessary, their design;
i) rationing and assignment of the category of workers.
5. Calculation of technical and economic indicators of the designed technological process.
6. Design of sites, departments, workshops.
The work on the creation of technological processes for the existing production has some peculiarities. It includes:
1. Analysis of the initial data for the development of the technological process.
2. Selection of an operating standard, group technological process or search for an analogue of a single process.
3. The choice of the original workpiece and the method of its manufacture,
4. Selection of technological bases.
5. Drawing up a technological processing route for existing equipment.
6. Development of technological operations.
7. The choice of means of technological equipment for control and testing. If necessary, order them.
8. The choice of means of transportation.
9. Appointment and calculation of allowances.
10. Rationing.
11. Calculation of economic efficiency.
12. Registration of technological processes.
One of the most progressive directions in the development of technological processes for the manufacture of machine parts is their typification.
The typification of technological processes is understood as such a direction in technology, which consists in the classification and typification of machine parts and their elements and then in the complex solution of problems arising in the implementation of technological processes of each classification group.
The rule for developing the use of typical technological processes is regulated by GOST 14.303-83.
The first stage of typing work is the classification of parts.
A class is a set of parts characterized by the commonality of technological tasks that are solved under the conditions of a certain configuration of these parts.
The criteria for the classification of parts are:
1) part configuration;
2) the dimensions of the part;
3) processing precision and quality of the processed surfaces;
4) material of the part.
Considering these signs, the parts can be divided into 17 classes: shafts, bushings, discs, eccentric parts, crosses, levers, plates, covers, housings, keys, struts, elbows, headstock, gear wheels, shaped cams, lead screws and worms, small fasteners.
Moreover, with the development of mechanical engineering, other classes of parts characteristic of certain industries (for example: turbine blades, ball bearings, etc.) are added to this classification.
In turn, the classes are subdivided into subclasses, groups, etc.: for example, shafts are smooth, stepped, hollow.
The design of typical technical processes is carried out in next order:
1. According to the drawings of the plant's product, a selection of parts is made that are similar in design and technological characteristics (Fig. 6.13, a - and).
2. The creation of a complex part is performed (Fig. 6.13, j). In this case, they are guided by the following:
a) the most complex part of the group is taken as a complex part, which includes all surfaces found in the rest of the parts of the group (Fig. 6.13, g). If, among the simpler parts of the group, there are individual surfaces (for example, a cone, a chamfer) that are absent in a complex part, then these surfaces are artificially added to the drawing of this part;
b) dimensions a complex part has the greatest;
c) the highest dimensional accuracy;
d) roughness parameters are the smallest of the parts included in the group
The sequence and content of technological operations and the manufacture of a complex part is established.
MINISTRY OF EDUCATION OF THE RUSSIAN FEDERATION
RYAZAN STATE RADIO ENGINEERING
ACADEMY
Department of technology REA
Explanatory note to the course project
on the course "Technology of engineering production"
on the topic "Development of a technological process for manufacturing a part
screen RGRA 745 561.002 "
Project completed
student gr. 070 A. A. Boltukova
Project Manager
Assignment …………………………………………………………………………………………………………… ..2
Detail drawing …………………………………………………………………………………………………… ..3
Introduction …………………………………………………………………………………………………………… 5
1. Design of a technological process using a typical ………………. …… .. …… ..6
1.1 Analysis of the initial data …………………………………………………………………… ... …… .6
1.2 Determination of the design and technological code of the part …………………………………… ..7
2. Assessment of the indicator of manufacturability of the design of the part ……………………………………………… 8
3. The choice of the method of manufacturing the part …………………………………………………………………… ... 9
4. Selection of blanks and technological bases ……………………………………………………………… ..10
5. Designation of processing modes …………………………………………………………………… .... 12
6. Choice of technological equipment ……………………………………………………………………… ..13
7. Technical regulation ……………………………………………………………………………… .14
7.1 Cutting with guillotine shears …………………………………………………………………… 14
7.2 Cold forming ………………………………………………………………………………… .15
8. Determination of the type of production ……………………………………………………………………… ... 17
9. Technical and economic indicators of the developed technological process ……………… ... 18
10. Calculation of the size of a batch of parts, blanks ……………………………………………………………… 21
12. Occupational safety measures …………………………………………………………………… 23
13. Conclusion ………………………………………………………………………………………………… ..24
14. Bibliographic list ……………………………………………………………………………… .25
Appendix 1 …………………………………………………………………………………………… ..… 26
Appendix 2 …………………………………………………………………………………………… ..… 27
Appendix 3 …………………………………………………………………………………………… ..… 28
Appendix 4 …………………………………………………………………………………………… ..… 29
At the present time in our country there is such a situation that the development of industry is the highest priority of all the tasks set. In order for Russia to take a solid place among the leading world powers, there must be a developed sphere in it. industrial production, which should be based not only on the restoration of factories founded in the Soviet period, but also on new, more modernly equipped enterprises.
One of critical steps on the way to economic prosperity is the training of specialists who would not have knowledge strictly limited by the framework of their profession, but could comprehensively assess their work and its result. Such specialists are engineers-economists who understand not only all the intricacies of the economic aspects of the operation of an enterprise, but also in essence production process, which determines this functioning.
The purpose of this course project is to familiarize yourself directly with the production process, as well as assess and compare its effectiveness not only from an economic, but also from a technological point of view.
The manufacture of a product, its essence and methods have the most significant impact on the technological, operational, ergonomic, aesthetic and, of course, functional characteristics of this product, and, consequently, on its cost, on which the price of the product, the demand for it from users, sales volumes, profit from sales, and, consequently, all economic indicators that determine financial sustainability enterprise, its profitability, market share, etc. Thus, the way products are made has an impact on the entire life cycle goods.
Today, when a competitive market forces manufacturers to move to the highest quality and cheapest products, it is especially important to evaluate all aspects of production, distribution and consumption of a product at the stage of its development in order to avoid inefficient use of enterprise resources. It also helps in improving technological processes, which are often developed not only based on the market needs for the manufacture of new products, but also taking into account the desire of manufacturers for cheaper and quick way obtaining existing products, which shortens the production cycle, reduces the amount of working capital associated with production, and, consequently, stimulates the growth of investments in new projects.
So, the design of the technological process is critical stage production of products, which affects the entire life cycle of a product and is able to become decisive when deciding on the production of a particular product.
Technological process - main part the production process, including actions to change the size, shape, properties and quality of the surfaces of the part, their mutual disposition in order to obtain the desired product.
Typical technological process is unified for the most typical parts with similar technical and design parameters. Engineers high class a technological process is developed for typical parts, and then, with their help, workflows are created for a specific part. The use of a typical technological process makes it possible to simplify the development of those. processes, improve the quality of these developments, save time and reduce the cost of technological preparation of production.
The development of a technological process includes the following stages:
Determination of the technological classification group of the part;
Selection by code of a typical technological process (selection of a method for obtaining a part);
Selection of blanks and technological bases;
Clarification of the composition and sequence of operations;
Clarification of the selected means of technological equipment.
To determine the technological classification group of the part, it is necessary to study the initial data, which contains information about the part and the equipment available for its manufacture.
Initial data contains:
Detail drawing
· Assembly drawing stamp
· specification
As a result of studying this data, we get:
Detail- screen - is a flat part with a design code:
RGRA. 755561.002.
Material: Steel 10 GOST 914- 56 - high-quality low-carbon steel with a carbon content of 0.2%. This alloy is well weldable and workable by cutting, as well as cold pressure. These properties prove the feasibility of using cold stamping for the manufacture of this part.
Range: sheet 1 mm thick. Hot-rolled sheets are usually made from this material.
Roughness: for the entire surface of the part, the height of the profile irregularities at ten points is Rz = 40 µm, the arithmetic mean deviation of the profile is Ra = 10 µm. Roughness class 4. The surface of the part is formed without removing the top layer.
Accuracy grade: highest quality 8
Technological process: in this case, it is most advisable to use cold stamping.
Cold stamping is the process of forming forgings or finished products in stamps at room temperature.
Part weight:
M = S * H * r, where S is the area of the part, mm2; H - thickness, mm; r - density, g / mm3
Sequential stamp
Stamp- a deforming tool, under the influence of which the material or workpiece acquires the shape and dimensions corresponding to the surface or contour of this tool. The main elements of the stamp are punch and die.
The design of this die includes a punch for punching holes with a diameter of 18 mm, as well as a punch for punching out the outer contour of the part.
This die is a sequential multi-step die that is designed for stamping parts from sheet material... The workpiece is manufactured in 2 stages: first, a hole with a diameter of 18 mm is punched, then the outer contour of the part is obtained.
When finding the technological classification group of the part, it is necessary to add the technological code of the part to the already existing design code of the part.
To determine the technological code of the part according to the available data, we will define a number of features, and then we will find their code according to the "Design and technological classifier of parts":
Table 1.
| № | Sign | Meaning | Code |
| 1 | Manufacturing method | Cold stamping | 5 |
| 2 | Type of material | Carbon steel | Have |
| 3 | Volume and dimensional characteristics | Thickness 1 mm | 6 |
| 4 | Type of additional processing | With a given roughness | 1 |
| 5 | Clarification of the view will add. processing | tumbling | 1 |
| 6 | Type of monitored parameters | Roughness, precision | M |
| 7 | Number of executive sizes | 3 | 1 |
| 8 | Number of features elements received add. Processing | 1 | 1 |
| 9 | Number of standard sizes | 4 | 2 |
| 10 | Material assortment | hot-rolled sheet | 5 |
| 11 | Material grade | Steel 10KP sheet 1,0-II-H GOST 914-56 | D |
| 12 | Weight | 6 g | 4 |
| 13 | Accuracy | quality-8, Rz = 40, Ra = 10 | NS |
| 14 | Dimensioning system | rectangular coordinate system consistently from one base | 3 |
Thus, the complete design and technological code of the part is as follows:
RGRA. 745561.002 5U611M.1125D4P3
Manufacturability is a property of the design of the product, which ensures the possibility of its release from least cost time, labor and material resources while maintaining the specified consumer qualities.
The value of the manufacturability indicator is determined as a complex one through the values of particular indicators in accordance with OST 107.15.2011-91 according to the formula:
ki is the normalized value of the particular indicator of the manufacturability of the part
The design of a part is technologically advanced if the calculated value of the manufacturability indicator is not less than it normative value... Otherwise, the design of the part must be modified by the designer.
Assessment of manufacturability of part 5U611M.1125D4P3
table 2
| Name and designation of a particular indicator of manufacturability | The name of the classification feature | Feature Grading Code | Normalized value of the index of manufacturability |
| Indicator of progressiveness of shaping Kf | Technological method receiving, defining the configuration (1st bit of the technological code) | 5 | 0,99 |
| The indicator of the diversity of types of processing Ko | Type of additional processing (4th digit of the technological code) | 1 | 0,98 |
| Indicator of diversity of control types Кк | Type of monitored parameters (6th digit of the technological code) | M | 0,99 |
| Indicator of unification of structural elements Ku | The number of standard sizes of structural elements (9th digit of the technological code) | 2 | 0,99 |
| Processing accuracy index Kt | Processing precision (13th digit of the technological code) | NS | 0,96 |
| Indicator of rationality of size bases KB | Dimensioning system (14th digit of the technological code) | 3 | 0,99 |
The standard value of the manufacturability indicator is 0.88. Calculated. Consequently, the design of the part is technologically advanced.
The technological process is accompanied by a number of auxiliary processes: storage of blanks and finished products, equipment repair, tool and tooling manufacturing.
The technological process conventionally consists of three stages:
1. Obtaining blanks.
2. Processing blanks and receiving finished parts.
3. Assembly of finished parts into a product, their setting and adjustment.
Depending on the requirements for the accuracy of dimensions, shape, relative position and roughness of the surfaces of the part, taking into account its size, mass, material properties, type of production, we select one or more possible processing methods and the type of corresponding equipment.
The part is a flat figure, so it can be made from sheet material using a die.
Product manufacturing route:
1) preparatory operation:
1.1) selection of blanks;
1.2) drawing up material cutting maps;
1.3) calculation of processing modes;
2) procurement operation - sheets are cut into strips using guillotine shears according to the cutting chart; this operation is performed by a low-skilled (1 ... 2 grade) cutter using guillotine shears.
3) stamping operation - giving the workpiece the shape, dimensions and surface quality specified by the drawing; this operation is performed by a more qualified (2nd ... 3rd grade) worker - a stamp operator, using a stamp equipped with a press.
4) tumbling operation - deburring; this operation is performed by a locksmith of 2 ... 3 categories on a vibration machine
5) control operation - control after each operation (visual), random control for compliance with the drawing. Dimension control is carried out using a vernier caliper for the contour of the part, and using plugs for holes.
The workpieces must be selected in such a way as to ensure the most rational use of the material, the minimum labor intensity of obtaining the workpieces and the possibility of reducing the labor intensity of manufacturing the part itself.
Since the part is made from flat material, then it is advisable to use sheets in the form of starting materials. Due to the fact that the part is manufactured by cold stamping in a sequential stamp, the sheets for feeding into the stamp must be cut into strips. It is necessary to find as much as possible rational way cutting material, which is determined using the formula:
where A is the largest size of the part, mm
δ - tolerance for the width of the strip, cut on guillotine shears, mm
Zн - guaranteed smallest gap between the guide strips and the strip, mm
δ "- tolerance for the distance between the guide strips and the strip, mm
a - side jumper, mm
Using the tables, we determine for a given part:
Suitable for this part round blanks.
Largest part size A = 36 mm.
Jumpers a = 1.2 mm; h = 0.8 mm
Width tolerance of the strip cut on guillotine shears δ = 0.4 mm
Guaranteed smallest gap between the guide strips and the strip Zн = 0.50 mm
Tolerance for the distance between the guide strips and the strip δ "= 0.25
Longitudinal cutting:
We get the utilization rate of the material:
Where SA is the area of the part, mm2;
SL - sheet area, mm2;
n is the number of parts obtained from the sheet.
As a result, we get:
Let's analyze the cross cut:
Thus, longitudinal cutting is more economical, since in this case the material utilization factor is higher than in the case of cross cutting.
We give cutting schemes for longitudinal cutting of the material (Fig. 1, 2)
a = 1.2 t = D + b = 36.8
Rice. 1. Cut the strips
Rice. 2. Cut the sheet.
Based on the design of the stamp, the basing of the workpiece is carried out with the help of the stop and the guide strips of the stamp, and the basing of the punches - along the geometric center of the punch of the matrix (in the office of the part).
The greatest accuracy is ensured by the coincidence of the design and technological bases. In this case, it will be difficult to ensure high precision, since a sequential punch assumes the movement of the workpiece from the punch to the punch, which, of course, increases the manufacturing error of the part.
Processing modes are a set of parameters that determine the conditions under which products are manufactured.
A sequential stamp assumes first - hole punching, and then - punching along the contour. Punching and punching are operations of separating a part of a sheet along a closed contour in a die, after which the finished part and the withdrawal are pushed into the die.
For a part obtained by stamping, the calculation of the modes consists in determining the stamping forces. The total punching force consists of the efforts of punching, punching, removing and pushing the part.
The piercing condition is determined by the formula:
where L is the perimeter of the hole to be punched, mm;
h - part thickness, mm;
σav - shear resistance, MPa.
From the table we find: σav = 270 MPa.
Thus,
The force of cutting a part along the contour is determined by the same formula:
Determination of the required forces of pushing the part (retreat) through the matrix is carried out according to the formula:
where Кпр - pushing coefficient. For steel Kpr = 0.04
The effort to remove the waste (part) from the punch is determined in a similar way:
where Ksn is the pushing coefficient. For steel Ksn = 0.035
The total punching force is found by the formula:
where 1.3 is the safety factor for strengthening the press.
For this part, we get the total punching force:
Technological equipment represents additional devices used to increase labor productivity, improve quality.
For the manufacture of a separator part, based on the available equipment, it is advisable to use a sequential die, when the punching of holes and the contour of the part is performed sequentially, which makes it possible to use simple design stamp, and as equipment for the technological process, guillotine shears and mechanical press.
The guillotine shear is a machine for cutting paper bales, metal sheet etc., in which one knife is fixedly fixed in the bed, and the other, placed at an angle, receives a reciprocating motion.
The main parameters, which is the most indicative for the selected equipment and which ensures the fulfillment of the modes provided by the technological process, for the press are the punching and pressing forces, and for the guillotine shears - the maximum thickness of the cut sheet and its width.
Table 3
Characteristics of scissors Н475
The calculated punching force Pp = 63.978 kN select [according to Appendix 5, 3051] the press so that its nominal force exceeds the value of the required punching force.
Table 4
Characteristics of the press KD2118A
Process regulation consists in determining the value of the piece time Tsh for each operation (for mass production) and the piece-calculation time Tsh (for mass production). In the latter case, the preparatory and final time Тпз is calculated.
The values and Tshk are determined by the formulas:
; Tshk = Tsh + Tpz / n,
where To is the main technological time, min;
TV - auxiliary time, min
Tob - time of service of the workplace, min;
Тд - time of breaks for rest and personal needs, min;
Тпз - preparatory and final time, min;
n is the number of parts in the batch.
Main (technological) time spent directly on changing the shape and size of the part.
Auxiliary time spent on installing and removing the part, controlling the machine (press) and changing the size of the part.
The sum of the main and auxiliary times is called operational time.
Workplace service time made up of time Maintenance(tool change, machine readjustment) and time for organizational maintenance of the workplace (preparation of the workplace, lubrication of the machine, etc.)
Preparatory and final time standardized for a batch of parts (per shift). It is spent on getting acquainted with the work, setting up equipment, consulting with a technologist, etc.
Let's calculate the standardization of the technological process of cutting a sheet of material into strips.
Since strips of material are fed into the sequential die, it is required to cut the steel sheets 10 into strips, the width of which is equal to the width of the blanks. For this we use guillotine shears.
Operation - cutting strips from steel sheet 710 x 2,000;
pitch - 38.75 mm;
18 strips from a sheet;
18 x 54 = 972 pcs. - blanks from a sheet;
manual way sheet feeding and installation;
manual waste disposal method;
equipment - H475 guillotine shears;
40 knife strokes per minute;
way of switching on with a foot pedal;
friction clutch;
the position of the worker is standing.
1. Calculation of the norm of piece time for cutting steel sheet
1.1. Take a sheet from the stack, put the scissors on the table, set on the back stop. The time for these operations depends on the area of the sheet and is usually indicated per 100 sheets.
With a sheet area, the time per 100 sheets is 5.7 minutes.
Following the directions for calculations:
1.1.1) when calculating the norm of piece time for a workpiece, we divide the time according to the standards by the number of workpieces obtained from the sheet;
1.1.2) when installing the sheet on the back stop, the time according to the standards is taken with a coefficient equal to 0.9;
1.1.3) the correction factor for a steel sheet thickness of 1 mm - 1.09.
1.2. Switch on the scissors 18 times. Since you need to get 18 strips: 17 inclusions of scissors in order to separate the stripes from one another and one more - to separate the last strip from the rest of the sheet. The time taken for this depends on how the guillotine shears are turned on.
When you press the pedal while sitting - 0.01 minutes per strip.
1.3. Cut the workpieces 18 times. The duration of this operation depends on the capabilities of the scissors.
At 40 strokes per minute and friction clutch shutdown - 0.026 min per strip.
1.4. Advance the sheet to the stop 18 times (since the sheet is divided into strips with the remainder, therefore it is necessary to separate the last strip from the exit). The duration of this action depends on the length of the sheet and the step.
With a sheet length along the cutting line of 2000 mm and a sheet advance step of 38.75< 50 мм время - 1,4 мин на полосу.
1.5. Take the waste from the scissors table, put it in the foot.
With a workpiece area, the time is 0.83 min.
Table 5.
Calculation of the norm of piece time for cutting a steel sheet
* - see paragraph 1.1.2.
The piece time rate is calculated by the formula:
That is the main cutting time;
TV - auxiliary time;
nд is the number of parts in the sheet.
for 100 parts;
Operation - cutting a part along the contour, holes in the part from the strip;
open stop stamp;
manual method of feeding and installing the workpiece;
manual method of waste disposal;
position of the worker - sitting;
crank press with a force of 63 N;
150 slider strokes per minute;
friction clutch;
way of switching on - with a pedal.
2. Calculation of the norm of piece time for stamping a part from a strip.
1.1. Take a strip, grease on one side. The necessary operations for the preparation of blanks for cold stamping are the removal of scale, dirt, defects, coatings and lubricants. The time spent on this depends on the area of the workpiece.
With such an area, the time per 100 pages is 5.04 minutes.
2.2. Insert the strip into the stamp as far as it will go. This operation is necessary to ensure the positioning conditions, its duration depends on the type of stamp, the length and width of the strip, as well as the thickness of the material.
With a strip width of 38.75 mm, the initial time is 5.04 minutes per 100 strips.
With a strip 2 m long, the coefficient is 1.08;
for a closed stamp - 1.1;
for steel with a thickness of 1 mm - 1.09.
2.3. Turn on the press. The duration of this action depends on the position of the worker and how the press is controlled.
To turn on the press with a pedal while sitting - 0.01 minutes per strip;
2.4. Stamp. The time it takes for stamping depends on the equipment used.
For a press with a number of slider strokes equal to 150 and a friction clutch - 0.026 min per strip.
2.5. The time it takes to advance the strip one step depends on the width and length of the strip and the type of stamp.
For a strip with a width of 38.75 mm, the main time is 0.7 minutes per 100 strips;
for a closed stamp - coefficient 1.1;
coefficient for a strip with a length of 2 m - 1.08.
2.6. The duration of the operation of removing the strip off (grating) is determined based on the strip of material.
With a strip of 38.75 x 2000 - 3.28;
for a closed stamp - 1.1;
coefficient for steel with a thickness of 1 mm - 1.09.
Table 6.
Calculation of the norm of piece time for stamping a part
Piece time rate:
nд - the number of parts obtained from the strip;
Кпр - coefficient taking into account the position of the worker (sitting - 0.8);
aobs - the time for organizational and technical maintenance of the workplace, for a crank press with a pressing force of up to 100 kN, equal to 5% of the operating time;
aot.l. - the time spent by workers on rest and personal needs, with a workpiece weight of up to 3 kg, is taken as 5% of the operational time.
According to GOST 3.1108 - 74 ESTD, the type of production is characterized by the coefficient of consolidation of operations. At the design stage of technological processes, the following calculation method is used the coefficient of consolidation of operations (seriality) behind the workplace (machine):
where Тт is the release cycle, min;
T sh. Wed - average piece time for the operation, min.
Release cycle calculated by the formula:
Ф - the actual annual fund of the time of the machine tool or workplace, h (let us assume Ф = 2000 h).
N - annual program of product release, pcs.
Average piece time defined as the arithmetic mean of the process operations. We will assume that time is mainly spent on cutting and stamping.
n - the number of operations (with the specified assumption k = 2)
It is given that the annual screen production program is equal to 1000 thousand pieces.
Release cycle min.
Piece time min.
Average piece time min.
Coefficient of consolidation of operations.
Depending on the value of Kzo, we select the type of production: at 1< Кзо <10 крупносерийный тип производства.
Large-scale production is characterized by the manufacture of products in periodic batches. In such production, special, specialized and universal equipment and devices are used.
For economic evaluation, two characteristics are mainly used: cost and labor intensity.
Labor intensity- the amount of time (in hours) spent on the manufacture of one unit of the product. The complexity of the process is the sum of the labor input for all operations.
Labor intensity of operations consists of the preparatory and final time Тпз, attributable to units of production, and the piece time Тsh spent on the implementation of this operation. Numerically, the complexity of the operation T is equal to the piece-calculation time Tshk, which can be calculated by the formula:
where n is the number of parts in a batch, determined by the formula:
where 480 minutes is the duration of one working estimate in minutes;
The preparatory and final time per shift consists mainly of the duration of the preparatory and final operations for cutting and stamping. Let's take:
min per shift;
min per shift.
Let's calculate the complexity of the cutting operation:
Piece cutting time: cutting;
Labor intensity of the cutting operation: min;
Let's calculate the complexity of the stamping operation:
Piece cutting time: cutting;
Number of parts in a batch: pcs;
Labor intensity of the stamping operation: min;
The reciprocal of the technological standard of time T is called production rate Q:
According to the obtained value of labor intensity, production rates:
The productivity of the technological process is determined by the number of parts produced per unit of time (hour, shift):
where F is the fund of working time, min;
The sum of the labor intensity for all operations of the process (in this case, for two: cutting and stamping).
Productivity of the technological process: parts per shift.
When making an economic assessment of an option for manufacturing a separate part, it is enough to determine it technological cost... It differs from the full one in that it includes direct costs for basic materials and production wages, as well as costs associated with the maintenance and operation of equipment and tools.
where Cm is the cost of basic materials or blanks, rubles / piece;
З - wages of production workers, rubles / piece;
1.87 is a coefficient that takes into account the cost of reimbursement of worn-out tools, equipment and the cost of maintaining and operating equipment, taken together, amount to 87% of wages.
The cost of the main material is determined by the formula:
where M n. R. - material consumption rate or workpiece weight, kg / piece;
With m. O. - wholesale price of material or workpiece, RUB / kg;
mо is the mass of sold waste, kg / piece;
Co - the cost of waste, taken at the rate of 10% of the cost of the main material, rubles / kg.
The mass of sold waste is determined by the formula:
where Mz is the mass of the workpiece, kg / piece;
Мд - part weight, kg / piece.
The workpiece weight is calculated by the formula:
where V is the volume of the workpiece of the part;
ρ is the density of the workpiece material, g / cm3;
Sl is the area of the sheet;
tl - sheet thickness;
n is the number of parts from the sheet.
Workpiece weight: kg.
The mass of the part has already been calculated earlier: Mz = 0.006 kg.
The mass of the sold waste: kg.
Wholesale price of steel 10: C m.o. = RUB 1100 t = RUB 1.1 kg.
Then the price of waste is: Co = 0.1 · 1.1 = 0.11 rubles · kg.
The cost of the main material: rub. on the detail.
The wages, depending on the specific conditions for the manufacture of the part, can be expressed as follows:
where Кз is a coefficient that takes into account additional payments to workers' wages (for vacations, for night shifts), as well as deductions for social insurance;
ti is the unit time norm for a technological operation, min./piece;
Si is the rate of the worker's qualification category, rubles / hour;
n is the number of technological operations.
In this case, we will take into account 2 operations: cutting the strips on guillotine shears and stamping the part. According to the already calculated values:
t1 = 0.0015 min;
t2 = 0.034 min;
The qualification category of the worker performing the cutting operation - II; and the punching operation is III.
The tariff rate for the first qualifying category of a worker is taken at 4.5 rubles / hour. The tariff rate for each subsequent qualifying category of a worker is increased by 1.2 times.
For workers in mechanical shops, wages supplements are about 4.5%, and social contributions - 7.8%, i.e. Kz = 1.13.
As a result, we get the wages per unit of the product:
Finally, we get the technological cost per unit of production:
10. Calculation of the size of the batch of parts
Release program: N = 1000 thousand pieces
Actual annual fund of time: Ф = 2000 hours.
Then the rhythm of production should be: children / hour
If Tsh stamping = 0.034 min, then children / hour
From the time to install and remove the stamp t = 30 + 10 = 40 minutes, and the salary of a worker of the 3rd grade Zr = 4.5 rubles / hour * 1.44 = 6.48 rubles / hour.
Then rub
- Let c2 '= 0.01 * 10-3 rubles. Then the batch size of parts
- Let c2 '' = 0.001 rubles. Then the batch size of parts
Calculation of the size of the batch of blanks
From adjusting the stops of the guillotine shears 3.5 min, setting the gap between the knives let it be 16.5 minutes, then tp.z. = 3.5 + 16.5 = 20min, and the cost of setting up a worker of the II category rub strips / hour.
If Tsh of cutting = 0.0015min, then strips / hour.
Let c2 '= 0.01 * 10-3 rubles, then the band.
11. Recommendations for adjusting the scissors
Gap between knives adjust depending on the thickness and strength of the material to be cut by moving the table, for which it is necessary to loosen the nuts of the bolts for fastening the table to the bed and set the required gap using 2 adjusting screws, after which the nuts must be tightened. To install the knives after regrinding, it is recommended to use shims made of foil or other thin sheet material.
The size of the gap is determined from the table. 11th century
Adjusting stops... To trim strips of various widths, the back, front and side stops, angle stops and bracket stops are used. Adjustment of the backgauge produced by moving it with handwheels along a ruler or templates. If the adjustment is carried out according to a template, then the latter is set with the edge against the stop to the lower knife, and the back stop is pulled close to its second edge and fixed with screws. The front stop is adjusted according to a template laid on the table. Stops - angles, stops - brackets and side stops are attached to the table in various positions, depending on the need.
Back rest
Knives 38.75 38.75
Bottom knife
Upper knife
Bottom knife
Rice. 3. Adjusting the scissors.
12. Labor safety
The main task of safety engineering is to ensure a safe and healthy working environment without reducing its productivity. For this, a large set of measures is being taken to create such conditions.
In order to prevent industrial injuries, moving parts of machine tools, working areas of equipment, technological equipment are supplied with protective devices (barriers, gratings, casings, shields, etc.). To provide an air environment at the workplace that meets sanitary standards, machines and other technological equipment are equipped with individual or group suction devices.
Environmental protection is of great importance. To reduce pollution, it is necessary to use waste-free technologies, the creation of treatment facilities that allow multiple use of the same volumes of water and air in protective systems.
When developing technological processes for the manufacture of parts, it is necessary to provide for specific measures to ensure safe working conditions, environmental protection during the manufacture of the part in question.
To ensure labor safety on cutting operations With the help of guillotine scissors, in addition to the safe construction of the tool, the worker must use cloth gloves to feed the sheet of material inside the scissors so as not to injure his hands, as well as a dressing gown to avoid damage to clothing when lubricating the sheet.
Environmental protection during cutting is carried out through the disposal of waste remaining after cutting the sheet into strips, and when working with lubricant, it should be carefully applied to the sheet of material.
When stamping the worker must be extremely careful when turning on the stamp, since it is not equipped with guards, and also use cloth gloves to feed the strip of material into the stamp.
Waste from stamping must be disposed of in an environmentally friendly manner.
Thus, the use of a typical manufacturing process facilitates the design, construction of a part, its manufacture and control.
By saving not only the time that would have been spent on development in the absence of such a "prototype", but also reducing the costs required to correct and dispose of defects when using unused technology, equipment and tooling, it is possible to obtain good economic indicators of the manufacturing and assembly process even for small batches of products and equipment.
The greatest time when using a typical process has to be spent on the technological preparation of production, which is necessary to fit the "prototype" for a specific part. Considering that many operations from the CCI are standard and could well be performed with the help of computer technology, currently the prevailing tendency is to fully or at least partially automate the process of technological preparation of production.
Applications Bibliography
1. Drits ME, Moskalev MA “Technology of structural materials and materials science: Textbook. for universities. - M. Higher. shk., 1990. - 447 p .: ill.
2. Zubtsov M. E. "Sheet stamping". L .: Mashinostroenie, 1980, 432 p.
3. Design and technological classifier of parts.
4. Lectures on the course "Technology of machine-building production" Lobanova S. A., 2001
5. Mansurov IZ, Podrabinnik IM Special forging and pressing machines and automated complexes of forging and stamping production: a Handbook. M .: Mashinostroenie, 1990.344 p.
6. Reference book of the normalizer / Ed. A. V. Akhumova. L .: Mashinostroenie, 1987.458 p.
7. Technology of engineering production. Methodical instructions for course design / Ryazan. state radio engineering. acad; Compiled by: A. S. Kirsov, S. F. Strepetov, V. V. Kovalenko; Ed. S. A. Lobanova. Ryazan, 2000.36 p.
8. Rules for processing technological documents: Methodological instructions for course and diploma design / Ryazan. state radio engineering. acad; Compiled by A. S. Kirsov, L. M. Mokrov, V. I. Ryazanov, 1997.36 p.
Economic efficiency of metal forming. The process of obtaining forgings by hot die forging. Calculation of cutting conditions when drilling. Turning technology. Advantages of closed die stamping. Precision processing of workpieces.
FEDERAL EDUCATION AGENCY
STATE EDUCATIONAL INSTITUTION OF HIGHER PROFESSIONAL EDUCATION
DON STATE TECHNICAL UNIVERSITY
Department "Technology of structural materials"
APPROVED Head of Department V.V. Rubanov "______" ________ 2008 EXPLANATORY NOTE For the course work Technology of automated mechanical engineering and instrument making (name of the discipline) on the topic: Development of the technological process for manufacturing a part Author of the work ___ Alexey Viktorovich Zatsepin Specialty_Robots and robotic systems Designation of the course work ____________ Group _______________ Project manager ______________ Kem Alexander Yurievich _____ (signature) (F.I. (date) (estimate) Rostov-on-Don 2008 Table of contents 1. INTRODUCTION 2. The main part 2.1. The process of obtaining forgings by hot die forging 2.2 Calculation of the cutting mode when drilling 2.3. Turning technology 3. Conclusion References INTRODUCTION:
Metal forming.
Metal working by pressure, a group of technological processes, as a result of which the shape of a metal workpiece changes without disrupting its continuity due to the relative displacement of its individual parts, i.e., by plastic deformation. The main types of metal fabrication are rolling, pressing, drawing, forging and stamping. O. m. Is also used to improve surface quality.
The introduction of technological processes based on metal fabrication is steadily expanding in comparison with other types of metalworking (casting, cutting), which is explained by a decrease in metal losses and the possibility of ensuring a high level of mechanization and automation of technological processes.
O. m. Can be obtained products with a constant or periodically changing cross-section (rolling, drawing, pressing) and piece products of various shapes (forging, stamping), corresponding in shape and size to finished parts or slightly differing from them. Piece products are usually cut. The volume of metal removed with all this depends on the degree of approximation of the shape and dimensions of the forging or stamping to the shape and dimensions of the finished part. In a number of cases, O. m.d. receive products that do not require cutting (bolts, screws, most sheet stamping products).
O. m.d. can be used not only to obtain blanks and parts, but also as a finishing operation after machining the part by cutting (mandrel, rolling with rollers and balls, etc.) in order to reduce the surface roughness, harden the surface layers of the part and create the desired distribution of residual stresses at which the service properties of the part (for example, resistance to fatigue failure) are improved.
O. m. Is carried out by the influence of external forces on the workpiece. The source of the deforming force can be a person's muscular energy (during hand forging, punching) or the energy created in special machines - rolling and drawing mills, presses, hammers, etc. Deforming forces can also be created by the action of a shock wave on the workpiece, for example, during explosive stamping, or by powerful magnetic fields. for example with electromagnetic stamping. Deforming forces are transmitted to the workpiece by a tool, which is usually hard, undergoing small elastic deformations during plastic deformation of the workpiece; in some cases, elastic media are used (for example, for stamping - rubber, polyurethane) or liquids (for example, for hydrostatic pressing).
Distinguish between hot and cold O. of m. Hot O. of m. Is characterized by the phenomena of return and recrystallization, the absence of hardening (work hardening); the mechanical and physicochemical properties of the metal change relatively little. Plastic deformation does not create banding (unevenness) of the microstructure, but leads to the formation of banding of the macrostructure in cast billets (ingots) or to a change in the direction of the fibers of the macrostructure (strands of nonmetallic inclusions) during the OD of the billets obtained by rolling, pressing, and drawing. The streaky macrostructure creates anisotropy of mechanical properties, in which the properties of the material along the fibers are usually better than those in the transverse direction. In cold oxygen production, the process of plastic deformation is accompanied by hardening, which changes the mechanical and physicochemical characteristics of the metal, creates banding in the microstructure, and also changes the direction of the fibers of the macrostructure. When cold metal is used, a texture appears that creates anisotropy not only of the mechanical, but also of the physicochemical properties of the metal. Using the influence of metal ore on the properties of a metal, it is possible to produce parts with the best properties with a minimum mass.
In the case of O. m., A change in the stress state diagram in a deformable workpiece makes it possible to influence the change in its shape. Under conditions of uneven all-round compression, the plasticity of the metal increases the more, the greater the compressive stresses. A rational choice of the operations of the o.m. and deformation conditions (hydrostatic pressing, extrusion with back pressure, rolling on planetary mills, etc.) not only makes it possible to increase the permissible change in shape, but also to use the o.m. for the manufacture of parts made of high-strength, hard-to-form alloys.
The scientific basis for the design and control of technological processes of metallography is the theory of metallocking, a scientific discipline that synthesizes individual sections of the physics of metals and plasticity theory. The main tasks of the theory of O.M.D .: development of methods for determining the efforts and work spent on deformation, calculating the size and shape of the workpiece, the nature of the change in its shape, methods for determining the permissible (without destruction or the appearance of other defects) changes in the shape of the workpiece, assessing the change mechanical and physicochemical properties of metal in the process of its deformation and finding the optimal conditions for deformation.
2. Main part
2.1 The process of obtaining forgings by hot die forging
Hot forging is a type of metal forming by pressure, in which the forging is formed from a heated workpiece in a special tool - a stamp. The stamp is a metal detachable form made of high-alloy stamped steel. At the final moment of stamping, when both halves of the stamp are closed, they form a single closed cavity - a stream corresponding to the configuration of the stamped forging.
Depending on the type of stamp, there is a distinction between forging in open and closed dies.
Stamping in open dies (Fig. 1a). Open stamps are called stamps, which have a special flaking groove 2 around the entire outer contour of the stamping strand, which is connected by a thin slot 1 with a cavity 3 forming a forging. In the process of stamping, at the final moment of deformation, the excess metal part is displaced into the groove, which is in the cavity and forms a flare (burr) along the forging contour. The formation of a burr leads to a slight increase in metal waste, but on the other hand, it makes it possible not to impose high requirements on the accuracy of workpieces by weight. All types of forgings can be obtained by stamping in open dies.
Fig. 1 Scheme of stamping in stamps:
a - open; b - closed
Stamping in closed dies (Fig. 1b). Closed stamps are those in which the cavity of the stamp 4 remains closed during deformation. Burr formation in them is not provided. When stamping in closed dies, it is necessary that the equality of the volumes of the workpiece and the forging is strictly observed. Therefore, the stripping of the blanks becomes more complicated, since when cutting off, a high precision of the blank by weight must be ensured. Most often, in closed dies, forgings are obtained that are stamped along the axis of the workpiece (upsetting at the end), round and square in terms of the type of rings, bushings, gears, pistons, rods with a flange, and others.
Development of a technological process diagram
The development of the hot die forging technology scheme includes the design of the forging, the determination of the mass, type and size of the initial workpiece, the determination of the temperature range of hot working by pressure, and the calculation of the operating conditions during forging. The flow chart is mainly determined by the configuration and size of the part to be produced. According to the drawing, the parts make up a drawing of the forging.
Forging design.
The forging belongs to the group of forgings stamped along the axis of the workpiece (stamping at the end), round in plan. To obtain a forging of this type, we use closed-die stamping. Select the plane of the die cut along the lower end of the part disk (diameter D2, height H).
1. Determination of the mass, type and size of the original workpiece.
1.1 Determine the mass of the part, kg:
G d = V d 10 -3 s10 -3,
Where V d is the volume of the part; mm 3, with the density of the weal, 7.8 g / cm 3
The volume of a part is calculated as the sum of the volumes of its three parts:
V d = V 1 + V 2 + V 3 = p / 4 (D 1 H1 + D 2 H 2 + D 3 H 3).
Due to the insignificant value of the limiting deviations of dimensions, the calculation is carried out according to the nominal dimensions of the part, mm: V d = 3.14 / 4 (75 2 * 15 + + 125 2 * 20 + 70 2 * 40) = 469035
G d = 469035 * 10 -3 * 7.8 * 10 -3 = 3.6
1.2 1.2 Tolerances and tolerances are selected according to tabular data:
D 1 75 ... 1.5; H 1 15 ... 1.4;
D 2 125 ... 2.1; H 2 40 ... 1.4;
D 3 70 ... 1.5; H 3 20 ... 2.2;
Part tolerances:
D 1p = 75 +1.6 - 0.8 H 1p = 15 +1.5 -0.7
D 2p = 125 +1.7 -0.9 H 2p = 40 +1.5 -0.7
D 3p = 70 +1.6 -0.8 N 3p = 20 +1.5 -0.7
D 4p = 15 +1.5 -0.7
1.3 Determine the estimated mass of the forging:
G p = 1.25 * G d = 1.25 * 3.6 = 4.5
1.4 Tolerances and tolerances are selected according to tabular data:
D 1 75 ... 1.5; H 1 15 ... 1.4;
D 2 125 ... 2.1; H 2 40 ... 1.4;
D 3 70 ... 1.5; H 3 20 ... 2.2;
Dimensions of forgings, mm:
D 1p 75 + 2 * 1.5 = 78; H 1p 15 + 1.4 = 16.4
D 2p 125 + 2 * 2.1 = 129.2; H 2p 40 + 2 * 1.4 = 42.8
D 3p 70 + 2 * 1.5 = 73; H 3p 20 + 2.3 = 22.3
Forging dimensional tolerances:
D 1p = 78 +1.6 - 0.8 N 1p = 16.4 +1.5 -0.7
D 2p = 129.2 +1.7 -0.9 H 2p = 42.8 +1.5 -0.7
D 3p = 73 +1.6 -0.8 N 3p = 22.3 +1.5 -0.7
We accept stamping slopes b 7?.
Radii of curvature r of the outer corners r1 = 2; r2 = 2.5; r3 = 2.
The inner radius is assumed to be 10 mm.
1.5 Determine the mass of the forging, kg:
G p = V p 10 -3 c10 -3
Where V p is the volume of the forging, mm 3
The volume of the forging is calculated as the sum of the volumes of its three parts, each of which has the shape of a truncated cone, mm 3:
V p = V 1p + V 2p + V 3p.
The calculation is carried out according to the minimum horizontal and
h 1p 7? maximum vertical dimensions, mm.
The volume of the truncated cone is determined by the formula, mm 2
V 1p = p / 3 H 1p (R 2 1p + r 2 1p + R 1p * r 1p) = 3.14 / 3 * 17.9 (40.8 2 +38.6 2 + 40.8 * 38, 6)
R 1p = r 1p * H 1p tg7? = 38.6 + 17.9 * 0.12228 = 40.8
V 2p = p / 3 H 2p (R 2 2p + r 2 2p + R 2p * r 2p) = 3.14 / 3 * 44.3 (69.6 2 +64.15 2 +69.6 2 +64 ,15)
R 2p = r 2p * H 2p tg7? = 64.15 + 44.3 * 0.12228 = 69.6
V 3p = p / 3 H 3p (R 2 3p + r 2 3p + R 3p * r 3p) = 3.14 / 3 * 23.8 (41.5 2 +38.6 2 + 41.5 * 38, 6)
R 3p = r 3p * H 3p tg7? = 38.6 + 23.8 * 0.12228 = 41.5
V p = 88044 + 617513 + 118905 = 824462
G p = 824462 * 10 -3 * 7.8 * 10 -3 = 6.4
The calculation of the mass of the forging after completing its drawing shows that the mass of the forging after assigning all allowances, tolerances and slopes remains in the same tabular range, and does not require recalculation.
1.6 Determine the mass and dimensions of the original workpiece.
Workpiece volume, taking into account 2% waste, mm 3
Vz = 1.02 * Vp = 1.02 * 824462 = 840951
Workpiece diameter, mm
Dz = 1.08 = 1.08 = 80.9 (with m = 2)
We accept Dz = 82 - the nearest larger diameter from a number of standard steel diameters.
Workpiece length, mm:
Lz = Vz / Sz = 840951/5278 = 159
Where Sz is the cross-sectional area of the workpiece, mm 2:
Sz = (pD 2 s) / 4 = 3.14 * 82 2/4 = 5278
2. Determination of the temperature range of stamping.
We determine the temperature range of hot working by pressure, in which the metal has the highest values of ductility, impact toughness and the lowest value of strength. To do this, we find on the abscissa axis of the iron-carbon state diagram a point corresponding to a carbon content of 0.15 (for Steel 15). Draw a perpendicular line from this point to the intersection with the solidus line, below which the alloy is in the solid state. The intersection point corresponds to a temperature of 1425? С. The maximum heating temperature of the metal is taken to be 100-150 ° C less, we accept 1300 ° C. Similarly, we determine the temperature on the line of curves of points А 3, which is equal to 850? С. The temperature of the end of stamping is taken 25-50 ° C higher, in order to prevent the formation of work hardening and cracks in the product, we take 900 ° C.
3. Approximate weight of the falling parts of the forging hammer, kg:
G = (3.5 + 5) F p = 4.2 * 134.5 = 564.9,
Where F p is the area of the projection of the forging on the plane of the parting of the stamp, cm 2
F p = p D 2 2p / 4 = 3.14 * 130.9 2 * 10 -2 / 4 = 134.5;
D 2p is the smallest diameter of the forging.
2.2 Calculation of cutting conditions when drilling
Drilling is the formation of a hole in a solid material by removing chips using a cutting tool - a drill. Drilling
carried out with a combination of the rotational movement of the tool around
axis - the main movement of cutting, its translational movement along the axis - movement of the feed (Fig. 1). On a drilling machine, both movements are imparted to the tool.
The speed of the main movement V is taken to be the peripheral speed of the point of the cutting edge farthest from the axes of the drill, m / s (m / min):
V = p * d * n / (1000 * 60)
where d is the outer diameter of the drill, mm, n is the rotational speed of the drill, min-1.
Feed S (or feed rate) is equal to the axial movement of the drill per revolution, mm / rev.
The cutting mode when drilling is understood as a set of values for the cutting speed and feed.
The cutting process when drilling takes place in more difficult conditions than when turning. During the cutting process, it is difficult to evacuate chips and supply coolant to the cutting edges of the tool. When the chips are removed, they rub against the surface of the grooves of the drill and drill against the surface of the hole. This results in increased chip deformation and heat generation.
The increase in chip deformation is affected by the change in the speed of the main cutting motion along the cutting edge from the maximum value at the periphery of the drill to zero at the center.
For the speed of the main cutting movement during drilling, the peripheral speed of the point of the cutting edge farthest from the axis of the drill is taken, m / s (m / min):
V = p * D * n / (1000 * 60),
where D is the outer diameter of the drill, mm; n is the rotational speed of the drill, rpm. The feed S (mm / rev) is equal to the axial movement of the drill per revolution. For the depth of cut when drilling holes in solid material, take half the diameter of the drill, mm:
t = D / 2, and when reaming t = (D-d) / 2, where d is the diameter of the hole to be machined, mm.
After turning, the part goes to the drilling operation.
1.In this part, you need to drill 1 hole with a diameter of d = 15mm. The material of the part is steel with a tensile strength of uv = 400 MPa. Twist drill material - high-speed steel grade P18. Cooling with emulsion. We will drill on a machine model 2H135. Calculation of the cutting mode:
2. Determine the feed S according to the formula
S = Stabl * Ke,
where Stabl = 0.28 (mm / rev). We choose from the table depending on uv = 400 MPa when drilling holes with a depth of 1? 3d, with an accuracy not higher than grade 12 in a rigid technological system (1? 3d? 36 = 12); Ke is the feed correction factor, Ke = 1, since a hole is drilled with a depth of 1< Зd, с точностью не выше 12-го квалитета и в условиях достаточно жесткой технологической системы(В связи с отсутствием дополнительных значений и параметров). S = (0,28-0,32) * 1 = (0,28-0,32) мм/об
The feed on the machine is set within the selected tabular range. We accept S = 0.28 mm / rev.
3.The cutting speed V is determined by the formula:
V = (Cv * dnv * Kx) / (Tm * Syv),
where Cy is a coefficient that takes into account the physical and mechanical properties
workpiece material and processing conditions;
T - drill durability, min;
For applications 2 and 3 we find:
К у = К mх * К uх * К lх - correction factor for cutting speed;
K mx = K g * (750 / uv) ny - a correction factor that takes into account the influence of the physical and mechanical properties of the material being processed;
K g - coefficient taking into account the material of the tool (for drills made of high-speed steel and the processed material - carbon steel Kg = 1);
nv-exponent (for HSS drills of the processed material - carbon steel at<400 МПа, nv=0,9);
К uх - a correction factor that takes into account the influence of the tool material (for high-speed steel К uх = 1);
К lх - a correction factor that takes into account the depth of the hole to be machined (at a depth of 1? 3d, Кlх = 1);
V = * 1 (750/400) -0.9 * 1 * 1 = 16.6 m / min = 0.27 m / s.
4. Determine the frequency of rotation of the spindle of the machine n, obtained by calculation:
n = 1000 * V / (p * d) = 1000 * 16.6 / (3.14 * 15) = 352 min-1
For the machine, we take the nearest lower rotational speed n = 250 min-1.
5. Determine the axial force during drilling P0 by the formula:
P0 = Cp * d xp * S ur * Kp = 55.6 * 15 * 0.28 0.7 * (400/750) 0.75 = 213 kgf;
From the application we find Cp = 55.6, XP = 1.0, SD = 0.7.
where Kp = (uv / 750) 0.75 = (400/750) 0.75 is a correction factor that depends on the material of the workpiece being processed; n is the exponent (when processing carbon steel, n = 0.75).
According to the passport data of the machine, the greatest axial force allowed by the feed mechanism of the machine is 1500 kgf. Therefore, the assigned feed S = 0.28 mm / rev is permissible.
6. Determine the torque Mk from the cutting resistance forces during drilling according to the empirical formula:
Мк = Сmd xm S ym Кm = 23 * 15 2 * 0.28 0.8 * (400/750) 0.75 = 1166 kgf * mm;
Cm = 23; Xm = 2.0; Ym = 0.8.
The torque is provided by the machine (permissible torque - 4000 kgf * mm).
7. Effective power Ne consumed for the cutting process:
Ne = Mcdop * n / 974000 = 4000 * 250/974000 = 1.02 kW.
8. Estimated power of the electric motor of the machine Ne:
Ne = N / s = 1.02 / 0.7 = 1.45 kW,
where s is the efficiency of the mechanisms and gears of the machine s = 0.7
9. Determine the main time T0. This is the time spent directly on drilling with a "manual" approach of the tool to the workpiece:
L = l + lvr + lper = 75 + 7.5 * ctg59 + 3 * 0.28 = 80.34 - full length of the drill movement, mm;
where l = 2 * d - hole depth, mm
1vr = d / 2 * ctgts-depth of penetration of the drill into the workpiece, mm,
1per? 3S - tool overrun length, mm;
We accept the angle at the top of the drill 2c = 118 °, recommended for
processing of steel. Thus:
To = 80.34 / (0.28 * 250) = 1.15 min
Hole size tolerance: D 4 = 14.4 +1.5 -0.7
2.3 Turning technology
Having considered the technological process of obtaining forgings by hot die forging, we proceed to consider the technology of turning.
When developing the designs of machine parts, the surface treatment of which is supposed to be done on lathe machines, it is advisable to take into account a number of special requirements that ensure their manufacturability.
Parts processed on lathes must contain the largest number of surfaces in the form of bodies of revolution. The design of the part must be such that its mass is balanced relative to the axis of rotation. The machining of balanced workpieces eliminates the effect of mass imbalance on the accuracy of manufacturing the surfaces of parts. When designing parts, it is necessary to use a normal range of diameters and lengths, which allows the use of standard cutting tools. Non-rigid shafts and bushings (long, thin shafts and thin-walled bushings) should be avoided in designs. The rigid design of bushings, glasses, cylinders allows them to be processed in cam chucks without resorting to special devices. When machining non-rigid parts, the error in the geometric shape of the machined surface is always greater than when machining rigid parts.
CHARACTERISTICS OF THE TURNING METHOD
The technological method of shaping the surfaces of the workpieces by turning is characterized by two movements: the rotational movement of the workpiece (cutting speed) and the translational movement of the cutting tool - cutter (feed movement). The feed movement is carried out parallel to the workpiece rotation axis (longitudinal feed), perpendicular to the workpiece rotation axis (transverse feed), at an angle to the workpiece rotation axis (oblique feed).
Varieties of turning: turning - processing of external surfaces; boring - processing of internal surfaces; undercutting - processing of flat (end) surfaces; cutting - dividing the workpiece into parts or cutting the finished part from the workpiece - bar stock.
On vertical semiautomatic machines, automatic machines and turning-boring lathes, the workpieces have a vertical axis of rotation, on lathes of other types - a horizontal one. Roughing, semi-finishing and finishing of workpiece surfaces are performed on lathes.
Cutting is the process of cutting off a metal layer from the surface of a workpiece with a cutting tool to obtain the required geometric shape, dimensional accuracy and surface roughness of the part. To do this, it is necessary that the workpiece and the cutting edge of the tool move relative to each other.
The main movements in metal-cutting machines are cutting movements that provide cutting off a layer of metal from the workpiece, and include the main movement and feed. The main movement is called the movement that serves directly to separate the chips. It is quantitatively assessed by the cutting speed, denoted by the letter V, with the dimension of m / s (m / min). In turning, this is the rotation of the workpiece.
Feed is a movement that ensures continuous plunge of the cutting tool into new layers of material of the workpiece being processed. The feed is designated by the letter 8 with an index indicating the direction: Sпр-longitudinal, Sп - transverse feed. In turning, the feed is the translational movement of the slide. Dimension of feed mm / rev.
Processing a workpiece on a lathe is called a turning operation. Operation is a complete part of the technological process, performed by the worker on one | workplace over a particular detail. The simplest element of a technological operation is a transition - processing of one surface with one tool at certain cutting conditions. If the cut layer is large, then it can be removed not in 1, but in 2 or more passes - one-time tool movements over the surface.
After receiving the part from the foundry, we will draw up a route for the turning operation of processing the part, select the tool and enter it in table 2.3.
table 2
Usta-nova | Transitions | Transition schemes | Cutter type | ||
Place the workpiece in the chuck and secure. Trim the butt end as "clean". | Undercut | ||||
Sharpen w73 +1.6 -0.8 to w70 +1.6 -0.8 for length 40 +1.5 -0.7 | Bushing thrust | ||||
Sharpen w 129.2 +1.7 -0.9 to w 125 +1.7 -0.9 to a length of 20 +1.5 -0.7 mm Place the workpiece in the chuck and fix it, cut the tarech to size 75 +1.6 -0.8. | Bushing thrust Undercut | ||||
Sharpening Ш78 +1.6 -0.8 to Ш75 +1.6 -0.8 for a length of 20 +1.5 -0.7 | Bushing thrust | ||||
To bore inner w14.4 +1.5 -0.7 to w15 +1.5 -0.7 over the entire length | Boring checkpoint |
2. The choice of the tool.
According to the turning route, we select the through cutter. When turning a given roughness of 20, we use the brand of a carbide cutting blade - T15K6 with the geometry: (q = 90 °, q1 = 45 °, r = 10 ° b = 12 °,
r = 1.0 mm. Durability period T = 80 min.
3 Calculation of the cutting conditions for the transition A2.
The depth of cut t is taken to be equal to the allowance t = z = 1 mm.
4 Select feed S. S = 0.5 mm / rev.
5 Determine the cutting speed.
V = C V / (t Xv * S Yv * T m) = 350 / (1 0.15 * 0.5 0.35 * 80 0.2) V = 184.2 m / min
6 Calculate the speed:
n = 1000V / (p * d) = 1000 * 184.2 / (3.14 * 15) = 3910 min-1
We clarify nst according to the passport data of the machine (see Table 6) and take the nearest smaller nst = 3150 min-1.
7 Determine the actual cutting speed:
Vf = (p * d * n cm) / 1000 = (3.14 * 15 * 3150) / 1000 = 148.4 m / min
8 Determine the main component of the cutting force (according to table 7):
Pz = with p * t Xp * S Yp * V Pr = 2943 * 1 * 0.5 0.75 * 148.4 -0.15 = 783.4 N.
9.Determine the cutting power:
NE = Pz * Vph / (1040 * 60 * h) = 783.4 * 148.4 / (1040 * 60 * 0.8) = 2.32 kW,
s = 0.7 - 0.9 is the efficiency of the mechanisms and transmissions of the machine tool.
Since Ne = 2.32< 10 кВт =Nст, то обработка на данных режимах выполняется.
3. Conclusion
After completing this course work, I got acquainted with the development of a technological process for obtaining hot forging, with the technology of turning and drilling.
Let's draw some conclusions:
1. Stamping in closed dies should:
1) Ensure the receipt of a forging of a certain geometric shape and dimensions;
2) When stamping in closed dies, it is necessary to strictly observe the equality of the volumes of the workpiece and forging;
3) A significant advantage of stamping in closed dies is the reduction in metal consumption, since there is no waste of burrs .;
4) Forgings obtained in closed dies have a more favorable microstructure;
5) When stamping in closed dies, the metal is deformed under conditions of all-round uneven compression at higher clamping stresses than in open dies.
In the course of the course work, a technological process for the production of a part by hot die forging was developed. The following issues were also considered: 1. The part forging was calculated. Allowances for machining and permissible dimensional deviations have been determined.
2. We determined the technical scheme for the production of forgings, completed the graphic material, which includes a drawing of the forging.
2. When machining parts, the following requirements must be observed:
1) precision of workpieces processing, quality of surface layers;
2) the correct choice of the cutting tool (the hardness of the material of the cutting part must significantly exceed the hardness of the material of the workpiece being processed, the shape of the tool must correspond to the operation being performed);
3) the technological map should reflect in detail all operations of the technological process;
4) when developing a design, parts that will be processed on lathes must contain the largest number of surfaces in the form of bodies of revolution. The mass of the part must be balanced with respect to the axis of rotation. It is advisable to avoid complex shaped surfaces, adhere to standard sizes and shapes of parts, which allows the use of standard cutting tools.
3. When developing the design of parts that will be processed on drilling machines, it is necessary to adhere to the following technological requirements:
1) holes, to which high accuracy requirements are imposed, must be made through, and not blind;
2) the surface into which the drill cuts must be perpendicular to the movement of the drill;
4) there must be free access to all elements of the part during processing and measurement;
The basis for increasing the economic efficiency of metal forming by pressure is, of course, technical progress. Technological progress is a process of improving production, technological methods and forms of organization of labor and production, which consists in continuous improvement of production on the basis of new technology, scientific achievements and advanced experience.
5. List of used literature:
1. Development of a process flow diagram for obtaining forgings by hot die forging. Method. Instructions for the implementation of practical work. DSTU, Rostov n / a, 2004.11 p.
2. Technology of turning. Method. instructions for doing practical work. DSTU, Rostov n / a, 2000.11 p.
3. Calculation of the cutting mode when drilling. Method. instructions for doing practical work. DSTU, Rostov n / a, 2000.11 p.
4. Forging and stamping: a reference book in 4 volumes V.2 Hot stamping. Ed. EI Semenova. M .: Mashinostroenie, 1986.592 p.
5. Technology of construction materials. Textbook for engineering specialties of universities / Under total. ed. A.M. Dalsky, 2004, 512 p.
6. Course and diploma projects (works). Registration rules. Enterprise standard. DSTU, Rostov n / a, 2001.34 p.
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Introduction
Mechanical engineering is one of the most important industries in the industrial complex of our country. For the national economy, it is necessary to increase the output of machine-building products and improve their quality. Technological progress in mechanical engineering is characterized not only by the improvement of the design of machines, but also by the continuous improvement of the technology of their production. It is important to produce any machine or part in a high-quality, economical manner and within a given time frame with minimal expenditures of living and materialized labor.
The development of new progressive technological processing processes contributes to the design of more modern machines and mechanisms, and the reduction of their cost. An urgent task is to improve the quality of machines and, first of all, their accuracy. In mechanical engineering, precision is particularly important for improving the performance of machines. Ensuring the specified accuracy at the lowest cost is the main task in the development of technological processes.
The main tasks in the field of mechanical engineering and the prospects for its development:
approximation of the shape of the blank to the shape of the finished product through the use of methods of plastic deformation, powder metallurgy, special shaped rolled products and other progressive types of blanks;
automation of technological processes through the use of automatic loading devices, manipulators, industrial robots, automatic lines, CNC machines;
concentration of transitions and operations, the use of special and specialized machine tools;
the use of group technology and high-performance equipment;
the use of effective cutting fluids with their supply to the cutting zone;
development and implementation of high-performance designs of cutting tools made of hard alloys, mineral ceramics, synthetic superhard materials, high-speed steels of increased and high productivity;
widespread use of electrophysical and electrochemical processing methods, application of wear-resistant coatings.
In the course project, according to the assignment, it is envisaged to develop a technological process for the manufacture of "Shaft", which is one of the most important parts of the mechanism for transmitting rotation at a given gear ratio.
1. General technical part
1.1 Service purpose of the product. Analysis of design and technical requirements
The shaft belongs to the class of shafts. The shaft is designed to transmit rotation at a given gear ratio.
Surface 3 has a parallel keyway for attaching a mating part. In end face 1 there is a threaded hole М8–7Н for fastening the part preventing axial displacement of the part from surface 3. On surface 15 there are straight-sided slots intended for fastening the mating part. The grooves 5, 9, 14 are technological and serve for the exit of the cutting tool. The groove 17 is designed to accommodate the retaining ring.
Table 1.1 Technical requirements
|
Surface name, nominal value, mm |
Surface assignment |
Accuracy |
Roughness Ra, μm |
|
|
End L = 290 mm |
||||
|
2, 6, 10, 12, 18 |
Chamfer 1CH45є |
Free |
||
|
Outer cylindrical W 25 mm |
Auxiliary design base |
|||
|
Keyway 40x8x4 |
||||
|
End L = 50 mm |
Auxiliary design base |
|||
|
Outer cylindrical W 24.5 mm |
Free |
|||
|
End L = 53 mm |
Subsidiary |
|||
|
Outer cylindrical W 29.5 mm |
Free |
|||
|
Outer cylindrical W 40 mm |
Free |
|||
|
End L = 81 mm |
Auxiliary design base |
|||
|
Outer cylindrical W 30 mm |
Main design base |
|||
|
Straight side slots |
Auxiliary design base |
|||
|
End L = 87 mm |
Free |
|||
|
Outer cylindrical W 28.5 mm |
Free |
|||
|
Chamfer 1.6X45є |
Free |
|||
|
Internal cylindrical М8 at L = 18 mm |
Auxiliary design base |
1.2 Analysis of manufacturability of a part
Shaft is a shaft type.
The shaft is made of steel 45 (GOST 1050–88), which is relatively well machined by cutting.
From the point of view of the rational choice of the workpiece, the pinion shaft belongs to quite technological parts. As a blank, you can use rolled products as the cheapest type of blank.
The geometric shape of the part consists of surfaces that are formed by the rotation of the generatrices about the axis and ends.
The surfaces are open for the approach and movement of the cutting tool. The configuration of the part does not allow to complete its complete processing in one setup. Therefore, the processing route will consist of a series of sequential operations and transitions.
The configuration of the part allows for normal tool entry and exit.
The shaft design allows for typical machining steps for most surfaces.
Accuracy and roughness indices are within economic limits: 6th grade of accuracy and roughness Ra 0.63 microns.
It is possible to implement the principle of constancy of bases on basic operations. The selected bases provide an easy, comfortable and secure attachment. This allows relatively simple and cheap fixtures to be used.
The part is machined in the centers and has sufficient rigidity, because l / d< 10 (294/42 < 10).
The design of the part ensures shock-free machining.
In the main operations, the possibility of using standard cutting and measuring tools and equipment (straight cutter, contour cutter, groove cutter, worm cutter, keyway cutter, centering drill, face cutter, center, ruler, vernier caliper).
Structural elements do not deform the tool at entry and exit.
As a result of the foregoing, the part is technologically advanced.
1.3 Material, its composition and its properties. Heat treatment modes
The shaft is made of steel 45 GOST 1050–88. Steel 45 belongs to the group of high-quality carbon structural steels. It is a tempering steel with a normal manganese content. [ 1.17]
Table 1.2 Chemical composition of steel
Table 1.3 Physical and mechanical properties of steel
Table 1.4 Types and modes of heat treatment
|
steel grade |
|||||
|
Heating temperature, | |||||
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