DE19729968C1 - Resistance welding with controlled relative motion of the components to be joined - Google Patents

Abstract

At least one of the components to be joined performs a controlled, preferably rotary motion relative to the other component(s) before and/or during the flow of the welding current. One of the electrodes rotates about its longitudinal axis (7) by a drive governed by the control system. The electrode and the component preferably have geometrical features which ensure transfer of the motion from the electrode to the component.

Description

The invention relates to a method and a device for resistance welding with controlled, preferably rotary, relative movement of the Welded parts.

Process and / or construction occurs in various resistance welding processes Partial geometry causes a relative movement of the welding joint surfaces. This is in particular, the case of pinch welding and projection welding with cone ring boss. It was found that connections with such a relative connections during the process result in very reliable connections (ZIS-Mitt., Halle 18 (1976) 4, pp. 381-384) and sometimes even less electri require energy (ZIS-Mitt., Halle 29 (1987) 4, pp. 367-374).

So z. B. in the evaluation of various resistance solder connections found that connections that arise without relative movement of the parts require a specific energy expenditure of electrical energy of about 150-250 Ws / mm ² . In contrast, an electrical energy requirement of only about 25-70 Ws / mm ^{2 was} determined for resistance solder connections with relative movement of the joining parts.

The size of the relative movement can also when welding with a cone ring boss can be influenced via the cone angle. The smaller the cone angle, the more The relative movement increases because the cone has the same parameters penetrates deeper into the cavity.

When comparing the results with cone angles of 60, 90 and 120 ° lie the welded connections with the two larger taper angles better results (ZIS-Mitt. 18 (1976) 4, pp. 381-384).

With very small cone angles with greater relative movement, there is a risk of that the movement does not immediately stop at the end of the current flow and so the connection formation is disturbed by the ongoing movement. Therefore lie Fern cone ring boss with large cone angle better results, because here in the In the initial phase of the welding, a relative movement takes place, but this too increasing welding time is slowed down considerably because the blunt cone has a large ß resistance is opposed.

Cone angles of 120 ° provide very reliable welded connections but also a big dependency regarding their relative movement to the joining partner the welding parameters.  

Hump welding with uncontrolled relative movement has that Disadvantage that the size of the relative movement from the geometry of the impact surface depending on the welding parameters and material, only to a very limited extent is flowable and above all not independently adjustable.

Due to the process, the butt welding and the flash butt welding are carried out ß always an axial relative movement that deflects radially in the joining plane becomes. The disadvantage of this method, however, is that the ridge is processed that must.

A number of welding processes use only those in motion existing or emerging energies for connection formation. So it is knows, friction welding to produce rotationally symmetrical welding connections between a rotationally symmetrical part and a second Part to apply (Richter, H., joining technology, welding technology, DVS-Verlag Düs seldorf 1995).

With newer machines that provide a precise braking of the rotating Enabling the spindle is, with restrictions, not even ro tatorische areas possible (welding technology, Vienna (1991) 7, pp. 108-111).

In addition to many advantages, friction welding also has several disadvantages. On the one hand, a relatively large, sharp-edged weld burr is created, which gel must be processed. On the other hand, the technology requires relatively high he axial forces and very stable machine frames to master the large Torques or moments of inertia.

It has already been proposed to use electrodes with ring-shaped contact elements equip, which are rotatable relative to the electrode axis and automatically after every electrode stroke by a small angle, so that always  new surface elements transmit the current and thus the electrode ver wear is slowed down.

A transfer of the rotary movement to the welded parts is not known.

It is also known (Richter, H., joining technology, welding technology, DVS-Verlag Düsseldorf 1995), by means of cold pressure welding, both overlap and To make butt weld connections. The disadvantage, however, is that this Process is limited to metals or alloys that work well let it be cold worked and its surface layers at a relatively low level Tear open deformations. Another disadvantage is the strong deformation or strong burr formation. Here, too, is usually a work-off of the ridge inevitable.

It is therefore an object of the invention, a welding method and a Vorrich to develop a relatively small, but defined and reproducible, relative movement of the welded parts independent of the other parameters Realize, he only a slight, especially not sharp burr formation testify and also for joining not above average ductile materials are suitable.

According to the invention, the object is achieved by combining the resistance press welding with a controlled relative movement solved as follows, where visually the basic inventive thoughts on claim 1 is referred. The further configuration of the solution according to the invention arises from claims 2 to 5.

It should be pointed out with reference to the claims:

• - An electrode is rotatably mounted to the longitudinal axis of the electrode.
• - A drive moves the electrode during the welding process.
• - Electrode and joining partner are configured so that a form and / or force finally ensures the transmission of the movement.

The task formulated above is thus fulfilled. In addition, it is still firm deliver that impact surface contamination, e.g. B. oxide layers, to the outside be pushed off. Furthermore, it should be noted that proven in tests was that by the invention the strength against a weld oh ne controlled relative movement is improved by about 40%.

The invention is described below using an exemplary embodiment the. It means:

Fig. 1 standard projection welding machine, according to the invention converted,

Fig. 2 detail on the hinge pin connection.

The device according to the invention is based on a standard projection welding machine with an upper clamping plate 1 and a lower clamping plate 3 .

The upper welding tool 2 is firmly flanged to the upper clamping plate 1 in a known manner. On the lower clamping plate 3, a base plate 5 is advantage mon, which is insulated by an insulating plate 4 relative to the lower clamping plate. 3 Above the base plate 5 there is a rotatable clamping plate 6 which is rotatably supported at its center about a vertical axis 7 . The lower welding tool 8 is firmly flanged onto the rotatable clamping plate 6 so that it moves together with the rotatable clamping plate 6 .

On the machine housing 9 of the projection welding machine, a controlled linear drive unit 10 is mounted, which moves a carriage 11 .

A sensor mounted on the carriage 11 boom 12 is connected via a joint 13 with a flange-mounted on the rotatable platen 6 levers 14, so that the linear movement of the carriage is converted into an angular rotation of the rotating cash clamping plate 6. 11

Additional current strips 15 close the current path - from the rotatable clamping plate 6 to the welding transformer, not shown.

The positions to be approached by the carriage 11 are set via a controller, not shown in the figure. The movement is started by control signals which are tapped from the welding machine control, also not shown.

Reference list

1

Top plate of a standard hump welding machine

2nd

Welding tool, firm

3rd

lower clamping plate

4th

Insulating plate

5

Base plate

6

rotatable clamping plate

7

vertical axis

8th

Welding tool, rotatable

9

Machine housing

10th

controlled linear drive unit

11

carriage

12th

boom

13

Hinge pin

14

lever

15

additional current band

Claims (5)

1. A method for resistance pressure welding with constant force or force program for rotationally symmetrical joints, characterized in that at least one joining partner performs a controlled, preferably rotational relative movement with respect to the other joining partner (s) before and / or during the welding current flow. 2. Setup and execution of the method according to claim 1, characterized in that an electrode is rotatably mounted to the electrode longitudinal axis, via one of the drive controlled by the welding control is moved during the welding process and the electrode and joining partner are preferably configured so that a positive connection for Transfer of motion is secured. 3. The method according to claim 1, characterized records that the angle of rotation is 0-30 °, preferably 1-5 °. 4. The method of claim 1 preferably for welding parts with surfaces foreign layers, characterized in that the rotational movement of preferably 5-10 ° before the flow of electricity begins. 5. Device for carrying out the method according to one of claims 1, 3 and 4, characterized in that to control the motion drive and continue to Changing the timing of movement and current flow is a common one Welding control is used.