RU2316695C1 - Torch for welding by non-consumable immersible electrode - Google Patents

Abstract

FIELD: welding processes and equipment, possibly welding by means of non-consumable electrode in different branches of industry.

SUBSTANCE: torch includes housing in which water cooled electrode holder is arranged. Clamp with tungsten electrode is mounted in said electrode holder and it is pressed from upwards by means of threaded plug. In lower part of housing water cooled nozzle is mounted through insulation sleeve and there is gas protective water-cooled member such as shoe. In inner cavity of electrode holder in its lower part there are helical ducts restricting inner annular flow of plasma generating gas. In lower part of housing between nozzle and insulation sleeve there is gas-forming lens with stepped inner hole into which gas is fed tangentially and by different angles relative to axis of torch (electrode) and also at different speeds. Two separate annular helical gas flows are formed. Gas protection shoe is mounted on welded article with possibility of motion along it due to free engagement with nozzle.

EFFECT: improved design of torch, enhanced efficiency of manufacturing process due to stable welding procedure, increased thickness of welded metal, improved strength of tungsten electrode, high-quality of welding bath, less number of flaws and improved geometry of welded seam.

2 cl, 4 dwg

Description

The present invention relates to the field of welding and may find application in welding with a non-consumable electrode in various industries.

Known torch for automatic submerged-electrode welding in a shielding gas environment (Passport for Installation GSPD-1M “Head for non-consumable electrode welding” GSPD1M. Operation manual 702130240000, Rzhev, OJSC “ELECTROMECHANICS, 2002). The burner comprises a housing with a water-cooling collet assembly mounted on it for fixing a non-consumable electrode (electrode holder), a water-cooled nozzle fixed to the housing through an insulating sleeve coaxial to the electrode. A water-cooled prefix for gas protection of the weld - shoe is fixed on the burner body. Shielding gas is supplied by two laminar annular flows: arc-forming and protective. The disadvantages of the known burner are: a small depth of penetration due to the low concentration of energy in the heating zone (since the arc is practically not compressed by the gas laminar flow and is able to deviate from the axis of the welded joint under the influence of electromagnetic forces in asymmetric electromagnetic and thermal fields, which leads to defects in the form of lack of fusion ); low resistance of the electrode when welding extended seams and the limitation of the welded thickness (up to 30 mm); a shoe mounted on the burner causes inconvenience in preparation for welding, does not provide high-quality protection during the welding process, and does not have the proper effect on the crystallization rate of the weld.

These disadvantages limit the use of the known torch for welding with a submerged electrode.

The objective of the invention is to increase the efficiency of the technological process of welding non-consumable submerged electrode.

The technical result consists in stabilizing the welding process, changing and simplifying the design of the burner, increasing the thickness of the metal being welded, increasing the resistance of the tungsten electrode, protecting the weld pool, reducing defects and improving the geometric parameters of the weld.

To achieve the specified technical result, the following burner design is proposed.

The burner contains a housing, inside of which there is a water-cooled electrode holder, with a collet with a tungsten electrode installed in it and pushed from above by a screw plug. In the lower part of the casing, a water-cooled nozzle is attached through an insulating sleeve and there is a gas-protective water-cooled device (shoe). In the internal cavity of the electrode holder, in its lower part, helical channels are made forming an internal annular flow of an arc-plasma gas. A gas-forming lens with a stepped inner hole is installed in the lower part of the housing between the nozzle and the insulating sleeve, into which gas is supplied tangentially and at different angles with respect to the axis of the burner (electrode) and at different speeds. Two independent annular spiral gas flows are formed. The gas shield is mounted on the welded product with the ability to move through it through free engagement with the nozzle.

Distinctive features of the claimed technical solution: a special device is mounted in the burner body - a gas-forming lens with a stepped inner hole, forming the flow of two gas circular spiral flows; the electrode holder body has helical channels forming a third annular spiral flow. The gas shield is mounted on the welded product with the ability to move through it through free engagement with the nozzle.

Figure 1 shows the burner body in section, figure 2 is a gas-forming lens, figure 3 is a section aa of the gas-forming lens, figure 4 is a section bb of the gas-forming lens.

The proposed burner is shown in FIGS. 1 and 2 and consists of a housing 1. Inside the housing there is a water-cooled electrode holder 2, in which a collet 3 is installed, with a tungsten electrode 4, pressed from above by a screw plug 5. Moving the electrode holder up and down when deepening and leaving the welding the bath is carried out by a helical rack, which engages with a helical gear: a drive from an electric motor (not shown). In the lower part of the housing 1, a water-cooled nozzle 7 is mounted through the insulating sleeve 6, and there is a gas-protective water-cooled device (shoe) 8. In the inner cavity of the electrode holder 2, screw channels 9 are formed in its lower part, forming an internal annular rotating stream of arc-plasma gas 10 coming through the fitting 11 located in the upper part of the electrode holder 2. In the lower part of the housing 1 between the nozzle 7 and the sleeve 6 is installed a gas-forming lens 12 with a stepped inner hole (figure 2), in which ngentsialno at different angles to the burner axis (electrode) and different velocities through the nozzle 13, 14 and 15, 16 are supplied with gas. Two independent circular spiral gas flows are formed: the middle 17, which stabilizes and compresses the arc, and the external 18, which performs protective functions. The gas shielding shoe 8 is mounted on the article to be welded 19 and slides along it by free engagement with the nozzle 7 through an opening in the shoe. This simplifies the design of the burner as well as the adjustment and welding process. It provides the best quality of weld protection and more intensive heat removal at the moment of crystallization and formation of the weld.

Figure 2 shows a gas lens 12, representing a device for forming a gas ring jet streams. The gas lens housing is a rectangular flange with an internal step hole and four diametrically located fittings 13, 14, 15 and 16. The axis of the fittings are directed at different angles relative to the axis of the electrode and tangentially to the cylindrical surfaces of the step hole. There are four assembly holes in the lens housing; in the upper part of the housing there is an annular recess, and in the lower annular protrusion for centering the lens in the burner. In section AA (Fig. 3), nozzles 13 and 14 are shown through which helium gas is supplied into the lens cavity with a smaller step hole diameter, which, leaving two jets, is formed into the jet stream 17.

In section BB (Fig. 4), nozzles 15 and 16 are shown, through which argon or argon gas with a low helium content is supplied and, leaving two jets into the lens cavity with a large step hole diameter, are formed into an annular jet stream 18.

The internal annular flow 10, consisting of helium with a small argon content, exiting the screw channels at a certain flow angle with respect to the axis of the electrode, encompasses the tungsten electrode 4, flows along it and, rotating, forms an arc discharge, which in its thermophysical properties approaches a plasma arc and also exerts significant pressure on the crater of the weld pool, thereby preventing the penetration of the vapor of the welded metal on the working surface of the electrode, which can significantly reduce erosion and electrode wear.

The rotation of the internal gas stream 10 contributes to compression, stabilization of the arc discharge along the axis of the electrode with a high concentration of the effect of heating the product, as a result, the penetration depth increases, which allows welding large thicknesses with a reduced weld width compared to the prototype with equal energy costs.

The average rotating stabilizing stream 17 of helium is formed by two annular jets exiting tangentially from the fittings 13 and 14 into the internal cavity of the gas-forming lens 12 (Fig. 2) into the gap between the surfaces of the electrode holder body and the smaller diameter of the stepped lens opening (Fig. 1). And since these jets relative to the axis of the electrode have a larger outflow angle and greater speed compared to the inner ring flow 10, the average rotating stream 17, not mixing with the internal stream 10, as if compresses the arc discharge, which leads to an increase in the speed of the arc flow and contributes to contraction and stabilization of the arc discharge, while simultaneously exerting pressure on the molten metal of the weld pool, prevents the penetration of the vapors of the metal being welded into the arc column, reducing their effect on the working surface electrode, which increases the service life of the electrode compared to the prototype. The effect of the rotating middle stream on the molten molten metal of the bath contributes to the intensity of its mixing in the weld pool, as a result of which it cleans with a decrease in the effect of blowing molten metal (splash), which allows to obtain dense high-quality welds.

The external protective annular flow 18 from argon or argon with a low helium content is fed tangentially by two jets through the nozzles 15 and 16 (Fig. 2) and is formed using the larger diameter surface of the stepped opening of the gas-forming lens 12 and the inner surface of the nozzle 7. The external annular flow with a large angle and a greater velocity of the jet outflow than the average stream, without mixing with two other annular flows, forms a protective stream at the outlet of the nozzle, covering the weld pool, and, when interacting with ited shoe holes 8 ensures a lower consumption of protective gases better protection of the welding bath from the environment in comparison with the prototype.

Thus, the design of the electrode holder and the presence of a gas-forming lens make it possible to obtain three annular gas flows rotating coaxially in contact with each other: internal - arc-forming, middle stabilizing and external protective, and the connection of the protective shoe with the nozzle simplifies the welding process, improves protection and formation of the seam.

The burner works as follows:

a protective shoe 8 is mounted on the assembled butt joint of the product to be welded 19, with the input and output plates, a nozzle 7 of the welding torch is introduced into the shoe hole, aligning the axis of the electrode 4 with the axis of the joint of the product. The depth of penetration of the electrode is set using an indicator placed in the body of the burner (not shown in FIG.). At the “Start” command, the gas is simultaneously supplied to the burner through fittings 11, 13, 14, 15 and 16 and to shoe 8 (not shown). After blowing, by touching the electrode 4 with the product 19, an arc is ignited, and a weld pool of molten metal begins to form, followed by immersion and movement of the electrode 4.

At the same time, three independent gas annular jet streams 10, 17 and 18 are formed inside the burner body, flowing at different speeds directly into the arc zone and the weld pool, without mixing with each other.

The internal arc-forming stream 10, consisting of helium or a mixture of helium with a small amount of argon (this mixture contributes to stable stabilization of the arc discharge), is formed using screw channels 9, rotating and washing the tungsten electrode 4, enters the arc zone, ensuring the stability of the arc discharge and fixation it along the axis of the electrode 4. The use of a rotating internal stream makes it possible to obtain an arc discharge with a higher energy concentration, which reduces the burial of the tungsten electrode 4 at injury to the depth of penetration.

The average stabilizing stream consists of helium, which is fed tangentially by two jets into the cavity of a smaller diameter of the stepped hole of the lens 12 through two diametrically located nozzles 13 and 14 and is formed into an annular jet gas stream 17, rotating in the same direction with the internal stream 10, but with a large angle and a higher rate of gas outflow to prevent mixing. Thus formed, the average annular flow contributes to the compression effect of the arc discharge formed by the internal stream 10. As a result, the welding current density and temperature in the arc discharge increase and, as a result, the penetration depth. The average stabilizing stream 17 exerts pressure on the surface of the weld pool, preventing the vapor of molten metal from interacting with the surface of the tungsten electrode, which leads to an increase in the service life of the electrode. And the simultaneous interaction with the molten metal of the weld pool improves the mixing conditions, which reduces the likelihood of a splash of liquid metal, resulting in a dense high-quality weld metal.

An external protective stream 18 is formed in the cavity of a larger diameter of the stepped opening of the gas lens 12, into which argon or a mixture of argon with a low helium content is tangentially supplied through the nozzles 15 and 16 with two jets. The external stream 18 with an even larger angle and flow rate than that of the average stream 17, without mixing with the two annular flows 10 and 17, descending along the inner surface of the protective nozzle 7, provides at the exit from the nozzle when interacting with the inner surface of the hole in the shoe 8 more effective gas protection of the weld zone with reduced shielding gas consumption.

Water-cooled gas protection shoe 8 slides on the surface of the welded product 19 in free engagement with the nozzle of the burner, providing more intense heat removal during crystallization and high-quality protection of the welded area compared to the prototype.

Welding on the lead plate ends after the Stop command. In this case, the electrode is gradually withdrawn, the welding current and the speed of the torch are reduced. After stopping, the flow of internal and medium gas flows is stopped, and then, after the seam cools down to 300-400 ° С, the external flow of protective gas is turned off.

Thus, the proposed torch for immersed electrode welding allows to increase the efficiency of the process by increasing the penetration depth without increasing the welding current and deepening the electrode, to increase the resistance of the tungsten electrode, to improve the metallographic and geometric characteristics of the welds and, in general, the quality of the welded products at no additional cost.

An example of the practical use of the burner is implemented under the production conditions of the IA3 branch of Irkut Corporation OJSC in the manufacture of frame designs from stamped VT20 titanium alloy blanks. The maximum thickness of the welded joints is 64 mm, the maximum length is 800 mm.

Claims (1)

A torch for welding with a non-consumable immersed electrode, comprising a housing, inside of which there is a water-cooled electrode holder with a collet with a tungsten electrode installed in it, pressed by a screw plug on top, a water-cooled nozzle is fixed through the insulating sleeve and a gas-protective water-cooled device is installed, characterized in that a gas-forming lens with a stepped inner hole is installed between the nozzle and the insulating sleeve of the lower part of the housing; giving two annular spiral gas flow at the bottom of the inner cavity of the electrode formed helical channels forming the third annular spiral flow, and water-cooled gas protection device placed on the welded surface is movable along it by the free engagement with the nozzle.

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