RU2505385C1 - Method of argon arc welding by nonconsumable electrode - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: thick-walled part is provided with a grove with one side higher than the other. The width of the groove is 2.5-3, and the depth is 0.25-0.45 against thin-walled part thickness. Joint surfaces of the parts are covered with a layer of cleanse flux for 1-10 minutes. Then the flux is removed from parts to 2/3 against thickness of thin-walled part and thin-walled part is inserted to the stop in higher wall of thick-walled part groove. Parts are melted in area of joint free from flux. When thickness of thick-walled part section is changed during welding, welding current is measured at stages not interrupting welding process. Parts are welded not later than 8 hours after flux removal. The method provides more strong and high-quality welding seam.

EFFECT: reducing labour intensity and cost of interlock of two parts with different thickness.

3 cl, 5 dwg

Description

Technical field

The invention relates to a technology for welding a non-consumable electrode of parts from aluminum and magnesium alloys, significantly different in thickness from each other. The invention can be used in mechanical engineering, automotive, tractor, chemical engineering and other industries.

State of the art

A known method of welding a non-consumable electrode of aluminum alloys (RF patent No. 2134628, dated June 17, 1998, B23K 9/23, authors: Kiselev OS, Sultanova AR, Tefanov VN,). The patent produces mechanical destruction of the oxide film at the welding site by a cutting tool, which is moved in front of the weld pool near the melting boundary, in the zone protected by argon.

The disadvantage of this method can be considered the complexity of the quality control of removal of the oxide film, since the burner is located in the immediate vicinity of the cutting tool. For the same reason, clogging of the weld zone by chips. This affects the quality of the weld.

A known method of fusion welding of light alloys (RF patent No. 2062686, from 09.21.1990, B23K 9/167, authors: Mamon MD, Novikov OM, Morochko VP, Tokarev V.O., Plisko V .N., Yarovinsky Yu.L.) In the patent, the flux in the form of a suspension based on fluoride salts is completely or partially applied to the welded edges in order to improve the quality of the weld metal. Before applying flux, a layer of metal powder based on nickel, lanthanum and cerium is applied to the welded edges.

To improve the quality of the seam, the patent uses flux and metal powder. The disadvantage is the increase in the number of control operations, the complexity of the implementation and the cost of the resulting weld. This method is used for butt welding and cannot be used for welding in the castle.

As a prototype for the method, a non-consumable electrode arc welding method was selected (RF patent No. 1436352 dated 01/23/1987., B23K 9/16, authors Dulikov V.P., Lapotko A.G.). In the method of arc welding with non-consumable electrode, seams of parts from aluminum and magnesium alloys, one of which is thin-walled and the other is thick-walled, a shoulder and a forming groove are made on the thick-walled part from the end face facing the thin-walled part.

The disadvantage of this method is the lack of flux, which in the presence of a large number of cavities increases the likelihood of the formation of oxide films that reduce the strength of the weld. In addition, the implementation of a large number of curly collars and grooves with their tolerances, increases the complexity and cost of the weld.

Disclosure of invention

The problem to which the invention is directed is to reduce the complexity and cost of the welding method while increasing the strength of the weld seam of the castle joints of two parts of different thicknesses.

The technical result achieved by solving this problem is to eliminate defects in the weld.

To obtain the specified technical result in the method of argon arc welding of non-consumable electrode parts from aluminum and magnesium alloys, one of which is thin-walled and another thick-walled, including grooves on a thick-walled part and the installation of a thin-walled part on a thick-walled, according to the invention, the groove is made with one wall of greater height, another wall smaller height. After the groove has been completed, a cleaning flux is applied to the mating surfaces of the parts for a period of one to ten minutes, inclusive, after which the flux is removed from the mating ends of the parts 2/3 of the thickness of the thin-walled part, the thin-walled part is installed all the way into the higher groove wall on the thick-walled part, parts are melted in an area not covered by flux.

When changing the thickness of a thick-walled part during welding, it is possible to switch from one section of a thick-walled part to another and at the same time stepwise change the welding current without interrupting the welding process.

To improve the quality of the weld, it is recommended to weld the parts no longer than eight hours from the moment of flux removal.

The shape of the groove allows you to hold the parts without bias during welding relative to each other, in addition, slag from the oxide film and spent flux is collected in the groove as a result of welding. As a result, the weld is more uniform, with fewer impurities, defects in the weld are eliminated.

Coating the surface with flux and removing part of the flux to obtain a cleaner weld is more economical than cutting metal.

Maintaining a continuous welding process by changing the welding current at a variable thickness of a thick-walled part also saves welding time and improves the quality of the weld.

To increase the quality of the weld, the welding time is limited to eight hours. Considering that after eight hours of welding, the oxide film formed on the surface of the surfaces being welded leads to a deterioration in the quality of the weld.

Brief Description of the Drawings

Figure 1 shows a cross-section of parts after grooving and applying flux.

Figure 2 shows a cross-section of parts after removing part of the flux.

Figure 3 shows the connection of parts before welding.

Figure 4 shows the cross section of the parts during the welding process.

5 shows a cross section of parts and a weld.

Embodiments of the invention

As shown in FIG. 1, a thick-walled part 1 and a thin-walled part 2 are involved in welding. A groove 3 is made on the thick-walled part 1 so that one side 4 thereof is higher than the opposite side 5. A layer is applied to the mating surfaces of the parts 1 and 2 cleaning flux 6. Flux 6 is located on the mating surfaces of parts 1 and 2 for at least one minute and no more than ten minutes.

If the flux layer 6 is on the surface for less than one minute, then it does not have time to harden, react with the surface, and clean it of the oxide film.

If the flux layer 6 is on the surface for more than ten minutes, then the destruction of the base metal occurs under the influence of flux elements.

The table shows the ratio of the time spent by the flux on the surfaces and the penetration depth. From table 1 it is seen that the best indicators of the depth of penetration are in the range from 1 to 10 minutes.

Table 1. The time spent by the flux on the surface (min) 0.7 min 0.9 min 1.0 min 10 min 11 min Penetration depth (mm) 0.5 (lack of penetration) 0.8 (lack of penetration) 1,0 1,0 Pores in the weld

As shown in figure 2, after ten minutes from the time of application of the flux from the mating ends of parts 1 and 2, the flux is removed 2/3 of the thickness of the thin-walled part 2. Table 2 below shows the presence of defects in the weld from the surface area with the flux removed. Table 2 shows that the absence of defects is observed at a value of 2/3 of the thickness of the thin-walled part.

table 2 The value of the surface coated with flux relative to the thickness of the thin-walled part Seam defects 1/4 The presence of pores 1/3 The presence of pores 2/3 No defects 3/4 Lack of penetration

After that, as shown in Fig. 3, a thin-walled part 2 is installed all the way into the higher wall 4 of the groove 3 on the thick-walled part 1. Using welding, the parts 1 and 2 are melted in the area of their joint, freed from the flux 6 by 2/3 of the thickness of the thin-walled part 2. In this case, the flux layer 6 reacts with the surface on which it was applied, cleaning it from the oxide film. Next, the mixture forms slag 9, which accumulates at the bottom of the groove 3, as shown in figure 4.

If during the welding process the thickness of the thick-walled part 1 increases, then there is a need to increase the magnitude of the welding current. For this, the TETRIX 350 AC / DC power source is adjusted to the value of the degree of change in the welding current before welding. A table is drawn of the relationship between the magnitude of the welding current and the thickness of the part being welded 1. During the welding process, the thickness of the part 1 is monitored and, according to the table, the magnitude of the welding current is increased or decreased stepwise. This ensures a more uniform heating of the welded parts, and the formation of a weld, eliminating possible lack of penetration, or burn through.

To maintain the quality of the weld at a high level, it is necessary that the oxide film, which is formed after cleaning part of the surfaces to be welded, does not form on them again. To do this, limit the welding process of parts 1 and 2 for no more than eight hours from the moment of removal of the flux layer 6.

Welding is performed by a non-consumable tungsten electrode in an argon medium. A specialized inverter current source “TETRIX 350 AC / DC” was used as a power source.

Welding is performed with through-penetration of a thin part 2. As shown in FIG. 4, a weld pool 7 occurs. During the existence of the weld pool 7, individual particles of the oxide film under the flux layer 6 are destroyed by the cleaning flux 6. A mixture of flux 6 and particles oxide film has a higher specific gravity compared to the molten metal of the weld pool 7, so it is concentrated in the root of the weld pool 7, forming slag 9.

During crystallization of the metal of the weld pool 7, a weld 8 is formed, as shown in FIG. Slag 9 is located in the forming groove 3. As a result, the weld 8 is spared from inclusions that violate its structure and reduce its strength.

Due to the shape of the groove 3, the presence of a flux layer 6 on the part of the contacting surfaces of parts 1 and 2, the resulting weld 8 does not contain a mixture of oxide film and flux 6, which means it is whiter uniform, has increased strength and quality.

Thus, the shape of the groove 3 allows you to hold the parts 1 and 2 without offset during the welding process relative to each other, in addition, a mixture of oxide film and flux 6 is collected in the groove 3 as a result of welding. As a result, the weld 8 is more uniform, with smaller impurities, eliminates defects in the weld 8. Coating the surface with flux 6 and removing part of the flux 6 to obtain a cleaner weld is more economical and less laborious. Changing the welding current when changing the thickness of a thick-walled part 1 additionally saves welding time and improves the quality of the resulting weld 8. All of these technical effects together solve the problem of reducing the complexity and cost of the welding method while increasing the strength of the weld seam of the joints between two parts of different thicknesses.

Industrial applicability

The most effective is the use of the proposed method in the manufacture of tanks and vessels in the aviation, chemical industry, mechanical engineering, and automotive industry. Where stiffeners (frames) are present in the structure and there is a need to connect parts of different thicknesses and variable thicknesses and increased requirements to the geometry of the product as a whole and to the quality of welds in particular.

The considered embodiment of the invention can be implemented on existing equipment. This shows its performance, and confirms industrial applicability.

Claims (3)

1. A method of argon-arc welding of non-consumable electrode parts made of aluminum and magnesium alloys, one of which is thin-walled and the other thick-walled, comprising making a groove on a thick-walled part and installing a thin-walled part on a thick-walled, characterized in that the groove is made with one wall of greater height than the height the other wall, while the width of the groove is from 2.5 to 3.0 of the thickness of the thin-walled part, and the depth of the groove is from 0.25 to 0.45 of the thickness of the thin-walled part, after completing the groove on the mating the surface of the parts is applied with a cleaning flux for a period of one to ten minutes, inclusive, then the flux is removed from the mating surfaces of the parts 2/3 of the thickness of the thin-walled part, the thin-walled part is installed all the way into the higher groove wall on the thick-walled part and the parts are melted in the zone, freed from flux. 2. The argon-arc welding method according to claim 1, characterized in that when welding a thick-walled part with a variable thickness, the welding current is stepwise changed when switching to a section of a different thickness without interrupting the welding process. 3. The method of argon arc welding according to claim 1, characterized in that the parts are welded no more than eight hours after removal of the flux.

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