Instructions for the installation of contact connections of tires between themselves and with the conclusions of electrical devices. Copper welding. Methods and technology of welding. How to cook copper? The quality of manual welding of copper

2.2. Copper busbar welding
Manual carbon arc welding

2.2.1. For manual arc welding of copper with a carbon electrode, the same equipment should be used as for welding aluminum (see table. 2.7.).

2.2.2. For welding, the materials indicated in Table. 2.10.
Table 2.10.
Materials for manual arc welding of copper with a carbon electrode

Material	GOST or TU	Purpose
1. Wire and rods made of copper M1, M0 1	GOST 16130-85	filler material
2. Carbon electrodes 2	TU 16-757.034-86	Welding non-consumable electrodes
3. Flux for welding copper "boron slag" (composition see Appendix 5)	-	Deoxidation of the metal to be welded
4. Graphite bars, asbestos		For forming and sealing the seam
5. Acetone or gasoline	GOST 1012-72* GOST 2603-79*
6. Cleaning rags	OST 63.46-84	Wiping the edges with solvent

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1 It is allowed to use bars cut from copper bars or sheets.

2 It is allowed to manufacture electric arc furnaces from electrodes (waste) (see Appendix 4).
2.2.3. When welding copper busbars, use the same fixtures and tools as when welding aluminum busbars. Due to the high fluidity of molten copper, it is necessary to form welded joints very carefully and reliably in order to prevent metal leakage during welding. Welding of copper busbars and compensators must be carried out on carbon linings with a groove under the joint; seal the ends of the seams with coal bars.

2.2.4. Preparation of tires for welding (except for straightening and cutting to size) includes processing of welded edges depending on the thickness of materials in accordance with GOST 23792-79, cleaning of welded edges in a section of at least 30 mm from their ends.

2.2.5. Before welding, filler rods should be cleaned of grease and dirt. If necessary, several filler rods are folded (twisted) together.

2.2.6. The tires prepared for welding must be laid and fixed in the device, a thin layer of flux should be poured onto the edges to be welded.

2.2.7. Starting welding, the welded edges should be heated with an arc, moving it along the joint until individual drops of molten copper appear in the arc zone; after heating the edges, concentrate the arc at the beginning of the seam until the edges melt and a weld pool appears; insert the filler rod into the rear edge of the weld pool (it should melt from its heat). It is not recommended to melt the additive in drops, introducing it into the arc, as this leads to intense oxidation of the metal and the formation of cracks in the seam. By dipping the heated end of the rod into the flux from time to time, introduce the flux into the weld pool.

Immediately after welding, it is necessary to cool the seam sharply with water. Where possible, copper bars should be welded in one pass. Welding modes and consumption of materials are given in table. 2.11.

2.2.8. Lap and corner joints of copper busbars should be made in the same way as aluminum busbars.

When welding fillet welds of these joints, the busbars should, if possible, be positioned in a "boat", because at the same time, due to the high fluidity of molten copper, the most favorable conditions are created to ensure good quality of welded joints (Fig. 2.21 a).

If it is impossible to perform welding in the "boat", forced formation of the seam with coal bars should be used (Fig. 2.21b). In this case, in order to avoid lack of fusion of the busbar edge, the branches should only be melted after the busbar has melted.

Rice. 2.21. Lap welding of copper bars

a) the location of the tires "boat"; b) the location of the tires "flat".

1, 2 - tires; 3 - weld; 4 - coal bar
Tire overlap welding modes correspond to those given in Table. 2.11.
Table 2.11.
Modes of manual welding of copper with a carbon electrode

Tire thickness, mm	Welding current, A 1	Carbon electrode diameter, mm	Filler rod diameter, mm	Consumption per 100 mm joint, g
Tire thickness, mm	Welding current, A 1	Carbon electrode diameter, mm	Filler rod diameter, mm	additives	flux
3	150	12	4	29	1
4	180	12	4	35	2
5	220	12	6	65	3
6	260	15	6	105	4
8	320	15	8	150	5
10	400	20	8	210	7
12	500	20	10	290	9
20	1000	30	15	450	12

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1 Direct polarity (minus power supply - on the carbon electrode).
Semi-automatic arc welding in shielding gas

2.2.9. This welding method is effective when connecting busbars up to 10 mm thick. When welding large thicknesses, pre-heating and post-heating are necessary.

2.2.10. For semi-automatic welding of copper in shielding gas, as in the case of aluminum welding, the equipment specified in p. 2.1.9, 2.1.10.

2.2.11. When welding, the materials listed in Table. 2.12.

2.2.12. When preparing tires for edge welding, they should be processed in accordance with the requirements of GOST 23792-79, cleaned and degreased at a width of at least 30 mm.

2.2.13. The electrode wire must be cleaned of grease and dirt and wound onto the semi-automatic cassette.
Table 2.12
Materials for semi-automatic argon-arc welding of copper

materials	GOST or TU	Purpose
Welding copper wire M0, M1	GOST 16130-85	Electrode wire, filler material
Graphite plates 1		Production of forming linings
gasoline or acetone	GOST 1012-72* GOST 2603-79*	Degreasing of welded edges
Cleaning rags	OST 63.46-84	Tire wiping
Argon gaseous	GOST 10157-79*	Protection of the welding zone from oxygen

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1 It is allowed to manufacture from waste graphite anodes and cathode blocks of electrolyzers, as well as electrodes for arc furnaces.
2.2.14. After laying and fixing the tires in the fixture, they should be welded using a technology similar to welding aluminum tires (see Fig. 2.22).

Rice. 2.22. Semi-automatic welding of copper bars in shielding gas

1 - tire; 2 - graphite forming lining; 3 - burner nozzle; 4 - seam;

5 - welding wire
Before welding tires with a thickness of more than 10 mm, it is necessary to preheat the edges to a temperature of 600-800°C. For heating, use a propane-oxygen or acetylene-oxygen flame.

Immediately after welding, the joint must be cooled with water.

Welding modes and approximate consumption of materials are given in table. 2.13.

2.2.15. Welding of single busbars in vertical and horizontal positions should be carried out using electrode wire with a diameter of 1.2 mm. In this case, it is necessary to use a device for fixing and heating tires. Tires up to 4 mm thick must be assembled for welding without cutting edges; with a thickness of 5 mm or more, one-sided beveling of the edges at an angle of 30 with a blunting of about 2 mm is required. The gap between the edges should not exceed 3 mm.

Tires should be preheated to 600°C before welding. The first pass should be performed with a "thread" seam; subsequent passes - with transverse oscillations of the burner.

Welding modes are given in Table 2.14.

After welding, the seam should be cooled with water.
Table 2.13
Modes of semi-automatic argon-arc welding of copper

Tire thickness, mm	Welding wire diameter, mm	Welding current 1, A	Arc voltage, V	Consumption per 100 mm joint
Tire thickness, mm	Welding wire diameter, mm	Welding current 1, A	Arc voltage, V	electrode wire, g	argon, l
3	1,2-1,6	240-280	37-39	20	10
4	1,2-1,6	280-320	38-40	24	11
5	1,4-1,8	320-360	39-41	33	12
6	1,4-1,8	360-400	40-42	47	14
7	1,6-2,0	400-440	41-43	64	15
8	1,8-2,0	440-480	42-44	84	17
9	2,0-2,5	480-520	43-45	106	18
10	2,0-2,5	520-560	44-46	130	20

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1 Direct current, polarity reversed.
Table 2.14

Page 6 of 16

When describing the welding technology, the terms set forth in § 3 are used.
For current conductors, copper grade MO with a copper content of 99.95% or grade Ml with a copper content of 99.90% according to GOST 434-71 is used.
The industry produces rectangular, round tires and a “round pipe” profile in accordance with GOST 617-72.

Welding copper due to its physical and chemical properties causes significant difficulties. Copper has a high thermal conductivity (almost 2 times the thermal conductivity of aluminum and 5 times the thermal conductivity of steel), so when welding, you have to use more powerful welding current sources or perform welding with preheated tires.
The increased fluidity of copper makes it difficult to form a seam, especially in a vertical position, and makes welding impossible in an overhead position.
In air, at normal temperature, the chemical activity of copper is low, and only in the presence of moisture and sulfur dioxide is it covered with a greenish-gray film of sulfate salt, which protects the metal from further oxidation.
When heated to +300°C, copper begins to actively combine with atmospheric oxygen, forming copper oxide CuO (black crystalline powder) and copper oxide CuO2 (dark red crystalline powder), which, when combined with copper, give a eutectic* with poor casting qualities , which makes it difficult to form a dense seam without pores. The presence of copper oxide and oxide in the alloy reduces the strength of the welded joint.
*Eutectic - a mixture of substances that has the lowest melting or melting point compared to mixtures of the same substances taken in other ratios.

Molten copper dissolves hydrogen well, and if copper oxide is present in the melt, hydrogen, reacting with copper oxide oxygen, forms water vapor, which worsens the quality of the weld, contributing to the formation of pores and hairline cracks in the metal (“hydrogen disease”).
To improve the quality when welding copper, measures should be taken to prevent the penetration of gases and moisture harmful to copper into the weld pool, which worsen the weld.
To protect the weld pool, fluxes are used, which, being in the molten state during welding, dissolve the oxide film, turning it into a fusible slag, as well as shielding gases.
When choosing one or another welding method, the requirements for welded joints are taken into account,
scope of forthcoming works, availability of equipment and materials.
The joint, regardless of the welding method, must be cooled with water after welding is completed to increase plasticity and maintain fine-grained seam.

Carbon electrode welding.

When melted, copper has a high fluidity, so welding with a carbon electrode must be carried out in the lower position and the welding site must be carefully molded using linings and bars. To ensure penetration of the root and formation of the reverse side of the seam, grooves are made in the linings, and holes are made in the forming bars.
Table 15

Welding is performed on direct current at direct polarity (minus the current source on the electrode). On tires with a thickness of 12 mm and above, the edges are cut at an angle of 25e. With a thickness of 10 mm and below, the cutting of the edges is not performed.
The gap between the ends of the tires, the depth and width of the grooves in the lining are given in Table. 15. Before welding, the ends of the tires and the filler metal are cleaned of oxide films and impurities, after which they are degreased with pure gasoline, acetone or white spirit. Cleaning is carried out with clean and degreased wire brushes made of wire with a diameter of 0.15 mm. As a filler metal, a wire made of copper grade MO or Ml is used.
The diameter of the wire is taken depending on the thickness of the metal to be welded. Instead of wire, you can use square bars cut from copper tires or sheets, while the side of the square is taken equal to the diameter recommended in the table. When welding tires with a thickness of 12-15 mm and above, a wire made of bronze of the BrKMtsZ-1 brand with a diameter of 2-3 mm is placed in the root of the seam and a little copper-phosphorus solder is added. This helps to improve the quality of the welded joint (reduces the likelihood of cracks in the welds).
Fluxes are used to remove the oxide film from the surface of the tires being welded, as well as to protect the liquid weld pool from oxidation during the welding process.
When welding with a carbon electrode, a “boron slag” flux is used, consisting of 95% remelted borax (Na2B407) and 5% metallic magnesium (Mg) in powder. In the absence of magnesium, sometimes p is used as a flux and one remelted borax, but this worsens the quality of welding. To prepare this flux, borax is first calcined in a crucible at a temperature of 200-300°C. The crucible is loaded on 7z>, since the drill swells when ignited.
After calcination, borax is mixed with metallic magnesium powder and melted at a temperature of 750-800°C. After the entire volume of boron slag is melted, it is poured onto a stainless steel sheet and covered with sheet asbestos, since it cracks when it cools and its pieces fly apart. The cooled flux is ground and sieved through a sieve having at least 1000 holes per 1 cm 2 . To prepare the flux, you cannot use uncalcined borax, dilute the flux in water or in liquid glass, since in these cases additional moisture will be introduced into the weld pool. The flux in the form of a dry powder is applied to the edges of the copper bars to be welded and to the filler rod. During welding, part of the flux is blown away by the arc, so the welder, in the process of welding, lowering the filler rod into a vessel with flux powder, transfers it to the weld pool. The flux powder adheres to the heated end of the filler rod in the form of a ball.

Tires up to 6 mm thick are welded in one pass without preheating. With tires with a thickness of 8, 10, 12 mm or more, preheating of the edges of the tires is used, in this case welding is performed in two passes. First, the edges are heated, starting from the end of the seam farthest from the welder, or from right to left. Heating is carried out with a stretched (15-25 mm long) arc, while making sure that the edges of the tires melt to the full thickness and the molten metal fills the groove in the lining. When heated, the filler metal is not injected. At the end of heating, the arc is concentrated at the beginning of the seam until a weld pool is formed, which the welder moves in the direction of welding during work.
During welding, the welder has an electrode holder in his right hand, and a filler rod in his left hand, which immediately after the formation of the pool are immersed in the molten metal, moving it behind the electrode
During the welding process, the welder reciprocates the electrode and filler so that the distance between them remains constant (8-10 mm), while at the same time the bath is mixed with a filler rod.

Rice. 26. Welded packages of copper busbars for an electric arc furnace.
The filler rod must not be removed from the weld pool before the end of welding, as this will cause oxides to enter the weld, degrade the quality of the weld and lead to the formation of cracks in the seam. For the same reason, it is impossible to introduce filler metal into the weld pool in drops. Immediately after welding, the seams are cooled with water.
This contributes to an increase in the plastic properties of the joint, reduced during the welding process. Welded packages of copper busbars for an electric arc furnace are shown in fig. 26.
When welding tires with a thickness of 25-30 mm, the tires are preheated on a forge or heated with a propane-oxygen torch to a cherry-red color (650-700°C). Before welding, the tires are laid with a slight slope (4-5 °) so that the molten copper does not flow forward of the arc and does not prevent the lower edges from melting. Welding is performed in three passes. The first pass, which the welder starts at the end of the seam and leads to the beginning, melts the bottom edges of the tires and fills the grooves in the lining. During warm-up, the welder monitors the complete melting of the edges. During the first pass, the foundation of a good-quality suture is laid. In this pass, the filler metal<не вводится. При втором проходе дугу концентрируют в начале шва до образования сварочной ванны, в которую вводят присадочный пруток, и начинается интенсивное плавление присадочного прутка и свариваемых кромок. При третьем проходе заканчивается формование шва.
Lap welding of tires is performed in the same modes as butt welding. The seam is formed with coal bars to protect the molten metal from spreading.
When mounting electrolyzers in cases where copper is used for onboard tires (electrolyzers of copper, nickel, etc.), it becomes necessary to weld jumpers 10x100 mm between heavy onboard tires 30 mm thick and more and blooms 40X40, 60X60, 92 X92 mm, etc.
The most rational is the welding of tire segments 10x100 mm at the MEZ both to the blooms and to the onboard tires so that only welding of these segments to each other is performed during the installation. In this case, the amount of work in the installation area is significantly reduced.
Welding of tire segments to onboard tires and blooms can be performed both overlapped and butt-to-butt.
The most correct is butt welding (Fig. 27, c). In this case, copper is saved, and, in addition, the butt weld is much stronger than the overlap. The segments are welded to the upper edge of the bead tire or to the bloom rib in a special device (Fig. 27.6), which ensures the formation of the seam. When welding, it is necessary to pre-heat the bead tire or bloom to a dark red color (650-700 ° C). In preparation for welding, a gap of 6-8 mm is set between the bead tire or bloom and tire segments. The welding current is 700-800 A. The arc is directed mainly to the blooms or to the on-board bus.

Rice. 27. Welding of jumpers between the onboard tire to the blooms.
a - a piece of tire 10x100 mm. welded to the side rail 30X500 we: b a bar for forming a seam; c - tire section 10X100 mm. welded to blooms 92x92 mm; g - a piece of tire 10X100 mm, welded to the bloom, but bent at an angle of 45 °; d - jumper welded to the onboard tire and blooms; 1 - side tire; 2 - blooms; 3 - forming bar: 4 - tire piece 10X100 mm; 5 - jumper.

During installation, the blooms are installed on the edge, but since welding of taps located at an angle of 135 ° to the bloom causes significant difficulties, welding is performed at a right angle (Fig. 27, c) and immediately after welding, with light hammer blows, it is bent to the required angle.
Sometimes it is necessary to weld segments of blooms with a size of 40X40; 60X60 or 92X92 mm. In this case, the edges to be welded are cut and installed in a special fixture. The main condition for welding is the preliminary heating of the blooms to 650-700°C. The current during welding is 1100-1200 A. Welding is performed in the same way as welding tires with a thickness of 30 mm or more. During welding, intensive melting of the edges to be welded and additives are maintained. After welding, the seam is cooled with water. If the weld has unacceptable defects, it is cut and the tires are welded again.

Cutting copper bars or blooms can also be done with a carbon arc. Cutting is quite efficient and can be used to prepare the edges of blooms. Before cutting, tires or blooms are preheated to a temperature of at least 800 °C. At the same time, the current is maintained at about 1000 A. The cutting time of the bloom 92 X92 mm does not exceed 3-4 minutes. However, the quality of the cut made by this method is much worse than with mechanical cutting.

For copper busbars, as well as for aluminum, there is a fairly large selection of welding methods that practically meets all the needs of electrical installation production. These include: carbon electrode welding, argon tungsten arc welding and semi-automatic, semi-automatic and automatic submerged arc welding, plasma and gas welding.

Welding copper is more difficult than welding aluminum, due to the nature of copper as a material. One of the main complications associated with copper welding is the need for preliminary or concomitant heating of tires with a metal thickness of more than 10-12 mm. This is due to the high thermal conductivity of copper. In addition, due to the fluidity of copper, the execution of vertical and horizontal seams is difficult, and ceiling seams are almost impossible.

True, it should be noted that some welders of very high qualifications also achieve ceiling welding, in particular, welding of fixed joints of tubular tires, which is a great art. It is required to literally “feel” the metal and regulate the welding process in such a way that the weld pool is of the minimum size and individual drops of metal solidify without having time to roll off. In this case, additional heating of the near-seam sections of tires to red heat by extraneous heat sources is required. Very

it is also desirable to use semi-automatic pulsed argon arc welding.

When choosing one or another tire welding method for specific conditions, it is useful to take into account the following features.

The best quality of the joints in terms of plasticity, density and appearance of the seams is provided by semi-automatic argon arc welding. It is used for metal thicknesses up to 12 mm and facilitates the execution of vertical, horizontal and ceiling joints when using an impulse attachment.

Manual TIG welding with a tungsten electrode also provides good connections, but its use is only possible in the down position.

Approximately equivalent to argon arc welding in terms of the quality of the seams is semi-automatic submerged arc welding, which is used in the lower position with a tire thickness of up to 14 mm. It is less convenient in installation conditions due to the somewhat bulkier equipment (flux feeders), the need for compressed air to supply the flux at the work site, and the lack of visual control over the formation of the seam (the seam is closed with a flux layer).

Automatic submerged arc welding is only suitable for long seams with large volumes of work. Such seams are found in the preparation of heavy busbars in electrolysis plants. It is not justified to perform short seams using automatic1 welding, which occur when butt-joining tires, since the time for installing the machine at the beginning of the seam and for the final operations is relatively long.

The most widely used in electrical practice is DC carbon electrode welding, which allows the connection of copper bars with a thickness of 30 mm or more with a completely satisfactory quality of the seams. Independence., from the presence of argon at the work site makes it the most accessible. The ability to pass through the electrodes higher currents than when welding by other methods, and due to this, to obtain a large heat input of welding allows us to refuse additional heating of the tires with a metal thickness of up to 20-25 mm. This is a great advantage of carbon electrode welding, as it simplifies the technology and organization of welding work.

The desire to completely abandon additional heating - when welding copper busbars, led to attempts to use plasma welding for this purpose, in which a large concentration of thermal energy is achieved.

As a result of the developments carried out by LenPEO VNIIPEM, it is possible to use plasma welding to connect copper busbars with a thickness of only up to 10-12 mm so far. Its advantages, along with the possibility of refusing additional heating, also include savings in filler material, so

8 R. E. Evseev, V. R. Evseev

how welding is done without a gap between the edges; more beautiful appearance of the seams (low reinforcement of the seam) and some reduction in the time required for welding. The disadvantages include the need for water cooling of the burner (plasma torch), the relative complexity of the plasma torch and its large mass (about 2 kg). The latter leads to increased fatigue of the welder during long-term work. In addition, two argon cylinders are required for welding, which complicates and weighs the installation.

Assessing the indicated features of plasma welding, the authors believe that this method will be more appropriate in electrical installation practice after the development and mastering of the technology for joining thick busbars. At present, it can be used in electrical workpiece workshops and should be considered as being in the stage of production testing.

Gas welding of copper tires is an auxiliary method due to lower productivity compared to electric and the low prevalence of gas welding equipment in electrical installation organizations. With the help of gas welding, busbar connections up to 30 mm thick can be made, although in the practice of electrical work there are known cases of gas welding of busbars of greater thickness. It is most expedient to use gas welding for connecting tubular water-cooled tires, as well as for welding parts for terminating and fittings of a water-cooling system to such tires.

For welding copper, due to its high thermal conductivity, only acetylene is used, since acetylene substitutes (propane butane, etc.) do not provide a sufficiently high flame power.

it is also desirable to use semi-automatic pulsed argon arc welding.

When choosing one or another tire welding method for specific conditions, it is useful to take into account the following features.

Manual TIG welding with a tungsten electrode also provides good connections, but its use is only possible in the down position.

8 R. E. Evseev, V. R. Evseev

For welding copper, due to its high thermal conductivity, only acetylene is used, since acetylene substitutes (propane butane, etc.) do not provide a sufficiently high flame power.

Copper welding has found wide application in both electronics and chemical engineering in the manufacture of devices for applications where high corrosion resistance is required. Therefore, the technology of copper welding, as well as the technology of welding non-ferrous metals and alloys, in general, is constantly being improved, despite the desire to save them. Before describing how to weld copper, it is necessary to clarify that in most cases, sheet copper parts and pipes are used for welding.

Note also that there are no special types of welding for copper products. And for their welding, all known methods can be used, with the exception of contact welding, which is used to a limited extent.

Manual arc welding of copper with metal electrodes

The expediency of using consumable electrode arc welding instead of gas welding of copper is dictated by technical and economic advantages, as well as in steel welding. First of all, this method is characterized by high performance. The speed of consumable metal arc welding is much higher than the speed of other welding methods. Arc welding of copper can be done manually, automatically submerged or in shielding gases. The welding of copper on semi-automatic and automatic machines is described below in the text. Now consider manual arc welding of copper.

Preparation of the welding site

If the thickness of the copper to be welded is 6-12mm, then it is recommended to perform a V-groove with a total edge opening angle of 60-70°. If a back seam is provided, the angle can be reduced to 50°.

Before welding, it is necessary to spread the copper sheets or strips at an angle to each other, with a gap of 2-2.5% of the length of the seam, see the figure on the right. If welding is performed without first spreading the sheets, it is recommended to pre-tack them with short seams about 30 mm long at a distance of about 300 mm from each other. Tacks are made with an electrode of smaller diameter and provide a gap between the edges of 2-4 mm. In the absence of a gap, the probability of overheating of the metal and increases. When making tacks, it should be taken into account that repeated heating of copper leads to the appearance of pores in the metal, therefore, as you approach the tacks, they must be cut down and cleaned. This will not take much time, because. tacks are performed at a shallow depth.

With a metal thickness of more than 12 mm, an X-shaped groove is recommended, which will require double-sided welding. If it is not possible to perform an X-shaped cut, then a V-shaped one is performed. At the same time, the consumption of electrodes and the welding time increase by almost one and a half times. With the X-shaped preparation of the edges, the tack is performed on the reverse side of the first seam and removed before starting the second seam.

Welding of a butt joint without cutting edges or with a V-groove is performed on linings that are pressed close to the joint, or on a flux pad. Steel, copper or graphite pads 40-50 mm wide are used with a forming groove.

Edge preheating is recommended before welding. Heating can be local, general or concomitant, depending on the dimensions of the product and the thickness of the copper being welded. Usually the heating temperature is 300-400°C.

Electrodes for arc welding of copper and coatings for them

Coated electrodes are used for arc welding of copper. The use of an electrode without a protective coating leads to the oxidation of the seam, unstable arcing and the appearance of defects in the weld (porosity). Electrode rods are used in the form of copper wire (which can be alloyed with silicon and manganese), bronze grade Br.KMts 3-1 or bronze grade Br.OF 4-03 and BR.FO 9-03.

Electrode rods of this composition alloy the weld metal with silicon, manganese, phosphorus (sometimes tin) and have a deoxidizing effect. Protective coatings are selected with a composition that ensures arc stability, metal deoxidation and slag formation. All this contributes to good formation of the seam and improving the quality of welding.

Modes of manual arc welding of copper

Welding is performed with direct current of reverse polarity. The use of alternating current often does not provide the necessary arc stability. Alternating current is possible to weld only if iron is present in the protective coating. In this case, it is necessary to increase the current strength by approximately 40-50%. But it should be borne in mind that the use of alternating current can lead to splashing of the electrode metal. Approximate welding modes are indicated in the table below.

Modes of manual arc butt welding of sheet copper with copper electrodes at direct current:

Welding speed is 15-18 m/h. If bronze electrodes are used, then the welding speed increases, because. the bronze electrode melts faster than the copper electrode.

When welding copper with a thickness of more than 10-12mm with an electrode diameter of 6-8mm, the welding current is increased to 500A.

When welding tee joints, the welding modes are approximately the same as for welding butt joints. In this case, it is necessary to establish a welded connection "in the boat".

Copper Manual Arc Welding Technique

Welding copper of great thickness is welded in several layers. Each previous layer is carefully cleaned before surfacing the next one. But small and medium copper thicknesses are best welded in one pass.

Welding is performed with reverse step seams, with a section length of 200-300 mm. The entire length of the welded section is divided into two sections: in 2/3 of the length of the seam and on the other hand 1/3 of the length. First, a long section is brewed towards a small one, and then a short one. The scheme of this welding is shown in the figure on the left. This welding technique significantly reduces the risk of cracks in the metal.

Welding is carried out in the lower position, or slightly inclined, and it is carried out "angle forward", i.e. the electrode should be inclined in the opposite direction from welding at an angle of 15-20 °. During welding, "swelling" of the welded edges can occur, with a decrease in the gap between them. In this case, the seam must be periodically corrected with a hammer or sledgehammer. In this case, it should be borne in mind that if welding is performed on a graphite lining, then it may crack. Therefore, steel linings, or copper ones, are preferable.

The quality of manual welding of copper

Pure borax or with the addition of other components is well suited as a flux. Read more about fluxes for gas welding of copper.

Resistance welding of copper

When welding copper, the most widely used type of resistance welding is butt welding. It is used when welding copper rods, wires, tapes, pipes. But this type of welding is more suitable for welding copper alloys. Spot and seam welding are not widely used in practice. We talked in more detail about resistance welding of copper products and modes for them on the page: "".

Video: general information about copper welding, its history

The video contains a brief history of copper and its processing from ancient times to the present. The video contains general recommendations for welding copper in various ways.