SU923768A1 - Resistance welding method - Google Patents

Description

The invention relates to micro-welding and can be used for welding materials of different thickness to thin metal films deposited on an insulating base.

The known method of resistance welding with a double electrode, in which the electrodes are mounted on the upper welded part (wire, fly) and pressed against the lower part. When an electric current is passed through, the upper part is mainly heated, and welding takes place both under the electrode and in the gap of £ 13.

However, this method cannot be applied to weld a high-conductive conductor to a thin film that has a significantly higher melting temperature compared to the conductor material, since in this case the melting and sediment of the upper part (conductor ^) occurs earlier than the lower part (film) reaches melting point.

2

The closest in technical essence to the present invention is a method whereby the upper part is mounted on the lower one and pressed with a double hot electrode, and the second electrode is installed on the lower part near the upper one and the welding current C2 is passed between them].

The disadvantage of this method is the impossibility of providing high-quality welding in the case of welding of highly electrically conductive material (for example, a stranded copper conductor) to a very thin and relatively high melting temperature film (for example, nichrome). In addition, if the film thickness is significantly less than the thickness of the part welded to it, then the volume of the molten material of the bottom part may not be sufficient to form a high-quality welding joint.

The goal of the invention is to improve the quality of welding.

This goal is achieved by the fact that in the method in which the upper part is installed on the bottom and pressed with a double hot electrode, and the second electrode is installed side by side on the lower part and passed between them. welding current, the lower part is melted in the area between the two electrodes by passing the welding current with the current density in the form of a trapezoid changing in this area.

FIG. 1 shows the state of the welded parts before passing the welding current; in fig. 2 the same, after passing the welding current; in fig. 3 section of the passage of the welding current, formed in the form of a trapezoid, in which the smaller side is under the cold electrode; in fig. 4 - section of the passage of the welding current, formed in the form of a trapezoid, in which the lower side is under the hot electrode.

To perform the welding of the proposed method, the top part 1 is mounted on the bottom part 2> which is a thin film deposited on the insulating base 3. The top part 1 is pressed against the bottom 2 by the hot electrode 4. The second electrode 5, which is cold, is installed near the top part 5 to the lower part 2. The heating of the electrode 4 is carried out from the transformer 6. After pressing and heating of parts 1 to a temperature not reaching its melting temperature, switch 7 switches on the welding transformer 8 and passes the welding current between the electrodes 4 and 5. Since the lower part 2 has a higher resistance due to the smallness of its cross section or physical properties, under the influence of the welding current it is straightened in the current passage where its density is sufficient to separate necessary for the melting of the film of heat. The melting of the film 2 can begin in any cross section of the current passage between the upper part 1 and the cold electrode 5, and if this section is given a certain shape, then you can shift the zone 9 of the maximum current density in one direction or another. Film 2, having started melting * in zone 9, expands the area of its complete melting. At the same time, in the direction of the cold electrode 5, it increases slightly, since

923768 ₄

This electrode, made of highly heat-conducting material, intensively cools film 2 in the zone adjacent to it. On the hot electrode 4 side, the opposite is observed: the film 2 on this side, in addition to the welding current, is heated by electrode 4, which also heats the entire cross section of the upper part 1, activating its surface and providing the possibility of physical contact between the welded parts at the level of interatomic bonds. Thus, the melt of film 2 formed on this side, heated by welding current and heat of electrode 4, under the influence of surface tension forces takes a spherical shape and rushes to the upper part 1, coming into contact with it and forming a welded joint. Considerable removal of zone 9 from the upper part can lead to the fact that heat from electrode 4 does not reach this zone and the melt of film 2 does not reach part 1. Excessive approach of zone 9 to part 1 creates such conditions that the amount of melt formed during melting of the film, It turns out to be insufficient for obtaining high-quality welded joint. To control the deposit of zone 9 of maximum densities, the passage of the welding current is formed in the form of a trapezium. By changing one of the sides of the trapezoid, it is possible to shift this zone depending on the size and physical properties of the materials being welded.

When testing the method, welding of a copper stranded conductor FD-100-0.05 to metal, an alloy film of X 20475 U thickness of 0.03 mm, deposited on an insulating base is carried out. The wire is pressed to the film with a hot electrode in the area of 3 mm. The second cold copper electrode is placed on the film at a distance of 2 mm from the wire. The optimal size of the cold electrode, which allows you to get the most simple and stable compound (500 g) is 4 mm. Increasing the width of the cold electrode causes the melting zone of the film to be mixed in the direction of the wire to be welded and to reduce the volume of the material to the film forming the welded joint. Connections are fragile. Reduce ^! the width of the cold electrode leads to

! the shift of the zone maximum current density in the direction of the cold electrode. Zone

ten

15

20

25

thirty

35

40

15

50

55

5 923768

melting the film does not reach the conductor, which leads to marriage.

The economic effect of the application of the proposed method is achieved by improving the quality of welding and reducing scrap during welding of relatively massive parts with thin films deposited on an insulating base.

ten

Claims (1)

Claim The method of resistance welding, in which the upper part is set to / bottom and pressed with a double hot electrode, and the second electrode is set15 poured next to the lower part to • pass; between them is the welding current, characterized in that, in order to improve the quality of welding, the lower part is melted in the area between the two electrodes by passing the welding current with the trapezium changing in this area.