RU2803615C1 - Method of arc welding with a non-consumable electrode in a shielding gas environment with a penetrating arc - Google Patents

Abstract

FIELD: arc welding.

SUBSTANCE: invention relates to arc welding of parts with a non-consumable electrode in a protective gas environment and can be used in automatic welding of butt joints of metals up to 8 mm thick. The assembly of the parts to be welded is carried out end-to-end without cutting the edges. Welding is carried out with a penetrating arc without filler metal, while starting and finishing it on the lead plates. A welding torch is used, having an electrode holder made of a material with high thermal conductivity, equipped with an electrode cooling system made in the form of a tube that supplies coolant to the electrode holder and directly to the non-consumable electrode. Welding is carried out in one pass at a speed of 40±5 cm/min.

EFFECT: method ensures high quality of the weld by increasing the penetration capacity of the arc with efficient cooling of the non-consumable electrode during the welding process and increasing the arc current density.

1 cl, 2 dwg

Description

The invention relates to the field of welding, namely to arc welding of parts with a non-consumable electrode in a shielding gas environment and can be used for automatic welding of butt joints of metals up to 8 mm thick.

A known torch for welding with a non-consumable immersed electrode contains a housing, inside of which there is a water-cooled electrode holder with a collet with a tungsten electrode installed in it, pressed from above by a screw plug, a water-cooled nozzle is fixed in the lower part of the housing through an insulating sleeve and a gas-protective water-cooled device is installed. In the lower part of the housing, between the nozzle and the insulating sleeve, a gas-forming lens with a stepped internal hole is installed, forming the supply of two gas annular spiral flows; in the lower part of the internal cavity of the electrode holder, screw channels are made, forming a third annular spiral flow, and a gas-protective water-cooled device is placed on the surface to be welded with the ability to move along it through free engagement with the nozzle. (2316695, MPK F23D 14/40)

The features of the invention coincide with the features of the analogue according to the welding method:

- assembly of parts to be welded end-to-end, welding with a non-consumable electrode in shielding gas, concentration of arc energy to increase the depth of penetration.

The disadvantages of the analogue are:

- ineffective cooling of the electrode, because the electrode is cooled at a considerable distance from the welding arc through a collet from the electrode holder;

- an increase in the depth of penetration is achieved by compressing the welding arc with several gas flows, which leads to an increase in the consumption of shielding gas and a complication of the design of the torch for supplying and orienting the shielding gas.

A known torch for arc welding with a non-consumable electrode in a shielding gas environment contains a water-cooled housing with a collet with an electrode installed in it and a nozzle attached to it, in which a tubular element is installed coaxially with the electrode. The tubular element is made in the form of a funnel-shaped bushing, in the conical part of which there are holes for forming a protective gas flow, in the cylindrical part there is a confuser channel for forming an arc-forming gas flow, in the upper conical part of the bushing there is an annular protrusion on the outer side, between the outer surface of the bushing and the inner surface In the nozzle, an annular gap is formed to form a protective gas curtain, and the sleeve is installed at a distance of 2-5 mm before the burner nozzle exit. (Patent for invention No. 2358847, IPC B23K 9/167, published 09/20/2009).

The features of the invention coincide with the features of the analogue in terms of the welding method: assembly of parts to be welded end-to-end, welding with a non-consumable electrode in shielding gas, concentration of arc energy to increase the depth of penetration.

The disadvantage is that an increase in the depth of penetration is achieved by compressing the welding arc with an arc-forming flow of shielding gas, which leads to an increase in the consumption of shielding gas and a complication of the design of the torch for supplying and orienting the shielding gas.

The closest to the claimed invention in terms of technical essence and achieved result is the compressed arc welding method (plasma welding), in which the welding process is carried out by an arc compressed by the nozzle channel and the flow of plasma gas. There is a known method of plasma arc welding, in which an arc discharge is excited between a non-consumable electrode of a plasma torch and the product being welded. Plasma arc welding is characterized by deep penetration of the base metal in a “keyhole” shape. Plasma arc welds sheets up to 9.5 mm thick end-to-end without cutting edges and filler metal.

Welding begins and ends on the lead strips. Welding is carried out at a speed of 10-12 cm/min.

This method was adopted as a prototype (Welding in mechanical engineering. Volume 1. edited by N.A. Olshanskaya, pp. 222, 456. Moscow “Machine Building”, 1978).

The features of the invention coincide with the features of the prototype in terms of the welding method: assembly of the parts to be welded end-to-end without cutting the edges, alignment of the axis of the non-consumable electrode of the welding torch with the plane of the joint of the parts, supply of shielding gas, ignition of the arc followed by movement of the torch along the joint of the parts, start and complete welding at the lead points strips, concentration of arc energy to increase the depth of penetration, welding is carried out with a penetrating arc (through penetration in the form of a “keyhole”) without filler metal.

The disadvantages of the method include: the complexity of its implementation, which consists in the need to supply and orient the plasma-forming gas, which complicates the design of the burner. In plasma welding, energy concentration is achieved due to compression of the arc by the nozzle channel and the flow of plasma-forming gas. During the welding process, the plasma-forming nozzle is subjected to strong heating, as a result of which it burns out and must be replaced.

The use of welding equipment of complex design to implement this method requires skills in setting it up and highly qualified welder, it is complex in design and expensive equipment, requires high gas consumption, and is inconvenient to operate.

In the above analogues, cooling of the electrode holder is used to increase the durability of the non-consumable electrode and is carried out at a considerable distance from the end of the electrode where the welding arc burns, which does not affect the area of electron emission.

Thus, welding parts with welded edges up to 8 mm thick using welding equipment described in the presented analogues is low-tech, labor-intensive, requires a highly qualified welder, skills and ability to work with welding equipment that is complex in design and operation, and requires high consumption gas to achieve penetration ability.

The problem to be solved by the invention: increasing the manufacturability of the method of arc welding of parts with a non-consumable electrode in a shielding gas environment with a penetrating arc using welding equipment with a cooling system that is simple in design, ensuring the quality of the weld, increasing the productivity of the welding process, facilitating the work of the welder, minimizing labor and economic costs of implementing the method.

Achieved technical result:

- welding of parts up to 8 mm thick in 1 pass, ensuring a high-quality weld without compression of the welding arc by an additional gas flow;

- increasing the penetrating ability of the arc due to the effective cooling of the non-consumable electrode during the welding process, during which the area of electron emission decreases and the arc current density increases, which increases the penetrating ability of the arc;

- transition to the penetrating arc welding mode due to cooling of the electrode (through penetration in the form of a “keyhole” is achieved and, as a result, a wedge-shaped weld in cross-section is obtained);

- reduction in gas consumption;

- increase in welding speed by 2-3 times in comparison with known methods - analogues of arc welding with a non-consumable electrode in a shielding gas environment.

In addition, it became possible to weld using inexpensive welding equipment of a simple, reliable design, compact in size, with an effective cooling system for the electrode with an electrode holder, which eliminates the need to supply and orient the plasma-forming gas; In addition, ease of use is ensured; highly qualified workers are not required in terms of setup/operation and welding work.

The technical result is achieved by the fact that in the method of arc welding with a non-consumable electrode with a penetrating arc in a shielding gas environment, which includes assembling the parts to be welded end-to-end without cutting the edges, aligning the axis of the welding torch electrode with the plane of the joint of the parts, supplying shielding gas, igniting the arc with subsequent movement of the torch along the joint parts without filler metal, welding begins and ends on lead strips; according to the invention, when welding parts, a welding torch is used, equipped with an electrode cooling system made in the form of a tube supplying coolant to the electrode holder made of a material with high thermal conductivity, and, directly, to non-consumable electrode, while welding is carried out in one pass at a speed of 40±5 cm/min.

This increases the depth of penetration of the welded edges; it is possible to weld metals up to 8 mm thick in one pass. without compressing the welding arc with an additional gas flow.

The effect is achieved due to the fact that with sufficient cooling of the non-consumable electrode during the welding process, the electron emission area decreases and the arc current density increases, which increases the penetrating ability of the arc and at a speed of 40±5 cm/min a transition to the penetrating arc welding mode (through penetration) occurs in the form of a “keyhole”) with minimal technical and economic costs.

The claimed invention, in comparison with the prototype and identified analogues, is characterized by a new set of features, the achievement of new technical results when welding parts with a non-consumable electrode with a penetrating arc in a shielding gas environment with welded edges up to 8 mm thick.

In fig. Figure 1 shows a welding torch equipped with a cooling system. In fig. 2 - assembly diagram - welding of parts.

The welding torch contains a housing 1, a gas nozzle 2, an insulator 3 fixed in the housing 1, an electrode holder 4, a cooling system made in the form of a tube (needle) 5 passing in the cavity of the electrode holder 4 along its axis, fixed at one end in the cap 6, the other - the output end of the tube 5 is placed close to the electrode 7, designed to supply coolant directly to the non-consumable electrode 7 and to the electrode holder 4, made of a material with high thermal conductivity. The coolant supplied through tube 5 interacts with the non-consumable electrode 7 heated by the electric arc and the electrode holder 4 heats up, thereby cooling the electrode 7, rises up the electrode holder 4 and is discharged through the cap 6 (Fig. 1). The parts to be welded are 8 and 9, 10 is the plane of the joint of the parts, 11 is the lead strips (Fig. 2).

The design of the torch is compact in size, easy to use, allows for maximum efficient cooling of the non-consumable electrode during the welding process, thereby achieving a significant reduction in the area of electron emission and an increase in arc current density, easy to use, and does not require highly qualified welders.

In fig. 2 - assembly diagram - welding of parts.

Example of a specific implementation:

Welding of parts 8 and 9 made of EP-679 material 8 mm thick was carried out as follows:

Assemble parts 8 and 9 end-to-end. Install lead strips 11 in the center of the joint. The axis of the tungsten electrode 7 of the welding torch is aligned with the joint plane of 10 parts 8 and 9, the welding torch and cooling system are turned on, the arc is ignited, and the process of cooling the electrode holder 4 and electrode 7 occurs with a coolant circulating through the cooling system consisting of the electrode holder 4, a tube (needles) 5 and cap 6, and protective gas is supplied through body 1 and nozzle 2. The electrode cooled in this way during the welding process is carried out along the joint 10 by the movement of the torch at a speed of 40±5 cm/min. at welding current 500±20A. Welding is carried out in one pass without cutting edges and without filler metal.

The welding speed of 40±5 cm/min was determined experimentally and was optimal and sufficient for switching to the penetrating arc welding mode and complete penetration of welded edges up to 8 mm thick and obtaining a high-quality seam.

As a result of welding parts 8 and 9, due to the cooling of the electrode, the arc current density increases, and, accordingly, the penetrating ability of the arc increases. During the welding process, a narrow, high-quality weld seam was formed with metal penetration through the entire thickness of the welded edges.

Welding modes for parts up to 8 mm thick differ in the amount of welding current, while the welding speed remains constant - 40±5 cm/min.

When welding at a speed of less than 40±5 cm/min, there is no transition to the penetrating arc welding mode and through penetration in the form of a “keyhole”, i.e. there is no formation of a technological hole in the lower part of the weld pool.

When welding at a speed of more than 40±5 cm/min, to ensure through penetration in the form of a “keyhole”, a significant increase in welding current is required, which reduces the efficiency of the electrode cooling system and reduces the quality of welding.

The declared welding method, in comparison with the prototype and identified analogues, is more technologically advanced, more productive, and requires minimal labor and economic costs.

Claims (1)

A method of arc welding of metal parts up to 8 mm thick with a non-consumable electrode in a protective gas environment with a penetrating arc, including assembling the parts to be welded end-to-end without cutting edges, aligning the axis of the electrode of the welding torch, which has an electrode holder made of a material with high thermal conductivity, with the plane of the joint of the parts, supplying shielding gas, ignition of the arc followed by movement of the torch along the joint of the parts without filler metal, while welding begins and ends on the lead strips, characterized in that when welding parts, a welding torch is used, equipped with an electrode cooling system made in the form of a tube supplying coolant to the electrode holder and directly to the non-consumable electrode, while welding is carried out in one pass at a speed of 40±5 cm/min.