HU186794B - Method for spot, roller or projection resistance welding of aluminium and its alloys from one side - Google Patents

Abstract

Field of the Invention The present invention relates to a welding current with a pulse-like substantial DC component on the elbows and the workpieces to be welded. Figure 2 -1

Description

The present invention relates to a method for spot, bulge or line welding of aluminum and its alloys.

As is known, spot welding, bulge welding, or line welding of resistors, especially in series production, is used to fasten structural members made of aluminum sheets or profiles of lower wall thickness. In this process, the workpiece to be welded is clamped between two opposing electrodes and a current is passed through the electrodes, which, of course, flows through the workpieces between the electrodes. The Joule heat generated by the flow current heats the material between the two electrodes. The electrode pressure exerted during the course of the current creates a bond between the softened or locally molten materials. This procedure is called mid-seam welding. The disadvantage is that on the one hand the workpieces to be welded must be accessible on both sides at the top and on the other hand there is a trace of welding on both sides.

However, there is a growing need for resistance welding in areas where there is no access to the workpieces to be welded from both sides, and for welded workpieces where, for example, from aesthetic point of view, there is only minimal trace welding. In the case of steels, the problem could be solved by welding the steels unilaterally. In this process, the electrodes are placed on one side, but the current flowing between the electrodes passes through both workpieces, since the steel is not a very good electrical conductor. However, the same procedure could not be applied to aluminum, since aluminum is a very good electrical conductor and, for electrodes placed on one side, the current passed through the outermost surface, thus practically no material could be obtained to close the circuit through each other.

The present invention was based on the discovery that, when a sufficiently high current concentration is applied to the material in a very short time, the high intensity current is able to pass through the top layer, essentially puncture it through the materials to be welded, and , which, of course, requires preliminary experiments and calculations, one-sided welding of aluminum can also be solved.

With known single- or three-phase AC resistance welding devices, the flow time of the current is 0.1-0.3 sec, which, however, does not generate sufficient current concentration to allow single-sided welding in aluminum.

It is therefore an object of the present invention to provide a method of selecting the welding current by which one-sided welding of aluminum can be achieved.

This was achieved in accordance with the present invention by imparting a pulse-like welding current through the electrodes, which pulse has a highly asymmetric, i.e., substantial DC component.

In the process of the present invention, it is advantageous to select a current pulse duration of between 0.005 and 0.02 seconds.

The process is preferably carried out by means of a capacitor welding apparatus, whereby the energy previously stored in the capacitor is discharged in a very short time through the electrodes and the workpiece, thus ensuring a high current concentration.

In a further preferred embodiment of the invention, a current concentrating bulge is formed on at least one of the workpieces to be welded.

The process according to the invention will now be described in more detail in the accompanying drawings, by way of example. The

Figure 1 illustrates an embodiment of the method of the present invention and a preferred embodiment thereof

Figure 2 shows a further preferred embodiment of the process according to the invention, a

Figure 3 shows welding of workpieces of different thicknesses, a

4, two pairs of electrodes are used, the

For the welding shown in Figure 5, a roller electrode was used

Fig. 6 shows a welding of a further embodiment of the roller, while Fig

Figures 7 and 8 show the bump welding using the process of the present invention.

Using the method according to the invention, the welding workpieces 1 and 2 are placed overlapping each other in the welding of aluminum materials or aluminum alloy with a capacitor resistance. 1, the two electrodes 3 and 4 are placed on one side of the workpieces 1 and 2 to be welded, in this example above workpiece 1, and below the workpiece 2 a conductive pad 5 is placed which exerts a compressive force exerted by the electrodes 3 and 4. picks. In the welding shown in Fig. 2, a non-conductive pad 6 is placed underneath the workpieces 1 and 2 to absorb the pressure exerted by the electrodes, whereas in the welding shown in Fig. 3, the pressure applied by the electrodes 3 and 4 is absorbed by the lower thicker workpiece. In the welding shown in Fig. 4, three workpieces 1, 2 and 2 'are welded to one another using the process of the invention by applying two pairs of electrodes 3, 4 and 3', 4 'and the first pair of electrodes 3 and 4 and 2 ', while the second pair of electrodes 3' and 4 'are designed to weld the workpieces 2 and 2'. Machine setup data for indirect welding of aluminum of various thicknesses and alloys, as well as some examples of shear-tensile strength of two points perpendicular to the force, are shown in the table below.

It should be noted here that the process according to the invention can be used when the bottom and bottom layers are thicker or thicker, i.e., have a minimum resistance.

The process of the present invention may also be implemented by forming the electrodes as rollers 8 and 9, as shown in Figure 5. The advantage of this embodiment is that the rollers also carry the material. The rollers 8 and 9 are in the process of welding and during the break the transfer of the workpieces 1 and 2 is performed.

By adjusting the pause time and the speed of the rollers 8 and 9, it is possible to carry out series welding or thread welding with high quality.

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186 794

The placement and configuration of the rollers 8 and 9 as electrodes are illustrated in FIGS. .

In the exemplary embodiment shown in Figure 5, the two rollers 8 and 9 are arranged one behind the other in the g direction of travel of the rollers, while the roller arrangement shown in Figure 7 is arranged so that the two current conductors 8 and 9 are parallel to each other. placed.

Figure 7 shows an embodiment of the rollers in which the two rollers 8 and 9 are integrated in one unit and the two rollers 8 and 9 are separated by electrical insulators 10. 7 and 8, the bump is formed from the first, preferably thicker, workpiece 2, and in Fig. 8, the upper, preferably thinner, workpiece 1 is formed. 15

Claims (7)

Patent claims A method for single-sided electrical resistance welding of aluminum or its alloys, characterized in that an impulse-like welding current with a substantial DC component is passed through the electrodes and the workpieces to be welded. 2. The method of claim 1, wherein the pulse response time is in the range of 0.005 to 0.02 sec. The method of claim 1, wherein the welding current is applied to the electrodes from a capacitor welding apparatus. The method of carrying out the elastic according to claims 1 and 2, characterized in that the thickness of the materials to be welded is the same. 5. A method according to claim 1 or 2, characterized in that the upper material (in contact with the electrodes) is the thinnest. 6. A method according to any one of claims 1 to 4, characterized in that the electrode is formed by two rollers disposed on one side. 7. A method according to any one of claims 1 to 3, characterized in that a separate current concentration form, preferably a bulge, is formed on at least one material to be welded. 11 pieces of figure National Office of Invention Fk .: Zoltán Himer codex -3186.794 International Classification Mark: B 23 K 23/00 aí.