DE8910447U1 - Support device for welding electrodes - Google Patents

Description

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DlPL-ING. GUIDO £f4döH)$ftDT.. PATENT ATTORNEY

7990 Friedrichshafen

Wilhelm Moeller
7775 Bermatingen

Support device for welding electrodes

The innovation relates to a device for supporting a welding electrode, preferably an adjustable point or bending electrode, which is attached to a new electrode holder which is connected to a carrier via an elastic intermediate member for the automatic repositioning of the welding electrode during welding processes.

3In resistance welding, the welding electrode often has to be repositioned within a few milliseconds, since material changes occur when the welding current flows through the workpieces to be welded together. In order to be able to do this automatically, an elastic intermediate element in the form of a spring is inserted between the electrode holder and the carrier, which is usually designed as a piston rod of a piston that feeds the electrode, in a known device of the aforementioned type. Although the welding electrode under pressure can thus follow the workpiece, which gives way due to the weld melt, the pressure range of such an intermediate element is limited and in the upper and lower pressure ranges exact reproducibility is not possible due to the spring characteristics. Another disadvantage is that installation is difficult and the

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Adjustment of the spring preload using a threaded spindle cannot be carried out precisely.

The aim of the innovation is therefore to design a device of the type mentioned at the beginning in such a way that not only is a welding electrode automatically repositioned depending on the welding melt that occurs, but that the respective welding pressure can also be set and measured without difficulty. Furthermore, a high level of reproducibility should be ensured, and the device should also be able to be used over a large pressure range and for pressure programs. The construction effort required for this and the structural dimensions should be kept low, but high sensitivity and operational reliability as well as a long service life should be ensured.

service life must be given.

According to the invention, this is achieved in that the elastic intermediate member provided between the carrier and the electrode holder is designed as a compressed air cylinder whose length is adjustable in the axial direction of the carrier, the mutually adjustable components of which are fastened on the one hand to the carrier and on the other hand to the electrode holder.

It is expedient to form the compressed air cylinder from two plates that are arranged at a distance from one another and can be adjusted relative to one another and are connected to one another via a bellows that is preferably attached to the carrier and the electrode holder in their outer regions and encloses a pressure chamber.

To avoid damage to the bellows,

the adjustment range of the two plates against each other by

be limited by the carrier and the electrode holder or by cooperating stops attached to the plates attached to them, whereby the stops can be formed in a simple manner by a collar attached to the end of the carrier and a sleeve with inwardly directed projections attached to the plate connected to the electrode holder, protruding into the pressure chamber, in which the collar of the carrier is guided so as to be movable to a limited extent.

If a device is designed according to the innovation, in

If a pneumatic cylinder with an adjustable axial length is used as an intermediate link, the components of which are connected to the carrier and the electrode holder, it is possible to easily adjust the welding pressure of the electrode using the pressure prevailing in the pressure chamber of the pressure cylinder and also to measure it using a pressure gauge. And this pressure can be changed and reproduced over a wide range, so that welding processes that are to be repeated at intervals can always be carried out under the same operating conditions. Since a pressure change in the pneumatic cylinder has to be made at short notice during a welding process, the welding pressure of the electrode can be changed in the form of a pressure program and adapted to the respective requirements, thus ensuring extremely versatile application on almost all welding machines.

Another advantage is that the sensitivity of the proposed intermediate link is high, that the service life of the electrode is increased and the spatter effect during welding is reduced. Any pressure generator acting on the carrier can also be used, which is therefore inexpensive. Despite low construction costs and favorable installation dimensions, a

A device designed in this way is easy to handle, resistant to interference and has a long service life.

The drawing shows an embodiment of a device designed according to the innovation for supporting a welding electrode and is explained in detail below. Here:

Figure i shows the device associated with a spot welding electrode in an axial section and

Figure 2 between two electrodes inserted by means of Projection welding of workpieces.

The device shown in Figure 1 and designated 1 serves to support a welding electrode 2, which can be pressed against a workpiece by means of a servo device 31. In Figure 2, two flat electrodes 3 and 4 are shown, by means of which two workpieces 5 and 6, of which the workpiece 5 is provided with a welding projection 7, are pressed against one another by means of the device i.

Since a welding current flows through the electrodes

3 and 4 the weld projection melts within 1 to 20 milliseconds, the electrode 3, or in Figure 1 the electrode 2, should follow the workpiece 5, which yields due to the weld melt, by the follow-up path s. In order to be able to do this, an elastic intermediate member in the form of a pneumatic cylinder 13, which is adjustable in its axial length, is inserted between the carrier 11, which is adjustable by means of the servo device 31, and an electrode holder 12 which holds the electrode 2 or 3. For this purpose, a plate

and a further plate 15 is attached to the electrode holder 12, which are connected to one another in an airtight manner by means of a bellows 16. In this way, a pressure chamber 17 is created, to which compressed air can be supplied via a compressed air connection 18. Depending on the pressure prevailing in the pressure chamber 17, the welding pressure of the electrode can thus be adapted to the respective requirements and/or measured, so that a high level of sensitivity and a high level of reproducibility are ensured, since the pressure can be set without any problems.

To prevent the bellows 16 from being accidentally damaged by the adjustment movements of the plates 14 and 15, their adjustment path is limited. For this purpose, a

A collar 19 is formed on the carrier 11 and attached to the plate 15

a sleeve 20 is welded into the pressure chamber 17, in which the collar 19 is slidably guided and which has inwardly projecting projections 21. The collar 19 and the projections 21 interacting with it thus form stops so that the plates 14 and 15 cannot be pulled apart so far that the bellows 16 would be damaged.

Of course, the distance between the plates and 15 can also be limited in other ways.

In the embodiment shown, the servo device 31 consists of a piston 33 inserted in a cylinder 32 that can be pressurized on both sides, the piston rod of which forms the carrier 11 that holds the plate 14, which can be welded or screwed on. To feed the electrode 2, pressure medium must therefore be fed to the pressure chamber 34 for its return to the pressure chamber 35. However, servo devices designed in a different way can also be used.

23.August
A 2993a e-1

Claims (1)

\V: ''P DIPL.-ING. G(JIUOSNOEÜH^ftÖTiPATENTANATT 7990 Frledrichshaieit William Muller
Bermatingen Protection claims 1. Device for supporting a welding electrode, preferably an adjustable spot or projection welding electrode, which is attached to an electrode holder which is connected to a carrier via an elastic intermediate member for the automatic repositioning of the welding electrode during welding processes, characterized, that the elastic intermediate member provided between the carrier (11) and the electrode holder (12) serves as '■ _¥ 15 in the axial direction of the carrier (11) in its length adjustable pneumatic cylinder (13) is formed, I' whose mutually adjustable components (plates ^! 7 14, 15) on the one hand to the carrier (11) and on the other hand are attached to the electrode holder (12). 2. Device according to claim 1, characterized, that the compressed air cylinder (13) consists of two plates (14, 15) arranged at a distance from one another and adjustable relative to one another, which are fastened to the carrier (11) and the electrode holder (12), which are connected to one another via a bellows (16) which is preferably fastened to them in their outer regions and encloses a diock space (17). 3. Device according to claim 1 or 2, characterized, % that the adjustment range of the two plates (14, 15) is limited relative to each other by means of cooperating stops (collar 19, projections 21). 4. Device according to claim 3, characterized, that the stops are formed by a collar (19) attached to the end of the carrier (H) and a sleeve (20) with inwardly directed projections (21) attached to the plate (15) connected to the electrode holder (12) and extending into the pressure chamber (17), in which the collar (19) of the carrier (11) is guided so as to be movable to a limited extent. Jd ¹ US 23. August 1989
A 2993/a RI