AT503310B1 - POINT WELDED ELECTRODE AND POINT WELDING PLIERS WITH SUCH ELECTRODE - Google Patents

Description

2 AT 503 310 B1

The invention relates to an electrode for spot welding of metal sheets, having a base body with an electrode shaft for arrangement in an electrode holder and with a surface which contacts the sheets during the welding operation.

The invention also relates to a spot welding gun for resistance welding of sheets, with pivotally mounted gun arms with electrode holders attached thereto, to which electrodes are attached, and with a winding device comprising a take-off roll and a take-up roll for winding and unwinding a tape to protect at least one electrode.

Although the electrode or spot welding gun can be used for welding a variety of workpieces, it is particularly suitable for welding metal flanges.

From EP 1 510 277 A1 a welding tongs for electrical spot welding of overlapping metal flanges is known. The welding gun has two electrically conductive gun arms with stepwise rotatable electrode holders, which comprise at least two longitudinally offset welding electrodes arranged in the rotational direction. In each rotational stage of the electrode holder, two welding electrodes of the two electrode holders located in the welding position are adjacent to each other. The axes of rotation of the electrode holders are parallel to each other and normal to the longitudinal extent of the sheet metal flanges. Preferably, the welding electrodes are distributed equidistantly, with the longitudinal sides in the direction of rotation of the electrode holder and in the longitudinal direction of the sheet metal flanges. The forceps arms and electrode holders may have flow-connected, outwardly sealed cooling channels. The electrode holders have a round or polygonal electrode disc with outwardly projecting welding electrodes, and are rotatably connected in stages to the associated gun arm by coaxially intermeshing cylindrical portions in electrical contact. For locking annular distributed axial Lagefixierbohrungen can interact with a dowel pin or a detent pin.

The disadvantage here is that the welding electrodes must be reworked or replaced after a certain time due to wear and tear. The reworking, such as grinding, the worn welding electrodes takes place on a separate post-processing device, which requires a larger space requirement and the maintenance costs increase due to the increased maintenance.

The object of the invention is to provide an above-mentioned electrode or a spot welding gun with such an electrode, which is particularly suitable for welding metal flanges with a small flange width. The effort when changing the electrode should be minimized to reduce maintenance costs.

The object of the invention is achieved by an above-mentioned electrode, in which the contact surface is elongated and arranged eccentrically. It is advantageous here that substantially narrower sheet-metal flanges of angled sheets can be welded with such an electrode, because the eccentric, that is off-center, arranged contact surface of the electrode can be brought closer to the side walls of the sheets to be welded than was the case with previous electrodes. Thus, the accessibility of the electrode for bending the angled metal sheets is substantially improved, whereby the welding point produced during spot welding can be moved further inward, ie in the direction of bending of the sheets, and thus the material required for the sheet metal flange can be reduced. Due to the elongated design of the contact surface, the width of the welding point can be reduced to a minimum while maintaining the quality of the welding point. Although in the present application mainly the welding of sheet metal flanges is mentioned, the electrode according to the invention also offers advantages for differently shaped workpieces. 3 AT 503 310 B1

According to one feature of the invention, the base body, so the area below the eccentrically arranged contact surface on an edged contour. Due to the angular contour of the base body, it can be achieved that parts connected to the main body can not rotate relative to the electrode.

In this case, the angular contour of the main body in particular four guide surfaces.

Advantageously, the cut in the contact surface of the electrode is formed substantially half-round. The contact surface cut in the plan view is formed in the form of a rounded rectangle at the corners. As a result, the area required for optimum weld spot quality can be achieved for the spot weld.

By the measures according to claims 3 to 6, the eccentric contact surface of the electrode can be realized.

According to a further feature of the invention, the main body of the electrode merges into an electrode shaft, which is formed from a cone with a round cross-section. This allows a simple conversion of the spot welding gun, if necessary without changing the electrode holders.

The main body of the electrode may have a bore for receiving a cooling device. By this measure, the wear of the electrode can be reduced and the durability or the life can be extended. The correct position of the electrode on the electrode holder can be ensured by means of at least one groove, rail or the like arranged on at least one guide surface of the main body of the electrode. This ensures that the eccentrically arranged contact surface is arranged close to any bends of the sheets to be welded.

With the main body or electrode shaft of the electrode, a pressure element, preferably non-rotatably connected to the electrode. The pressure element exerts a force on the electrode or on the sheets to be welded during the welding process.

The pressure element has a recess which is formed corresponding to the main body or electrode shaft. As a result, an optimal connection between the electrode and the pressure element is achieved.

The pressure element may be formed for example by an elastomeric spring.

If a sliding cap for guiding a band is provided in the region of the contact surface of the electrode, a band for protecting the electrode can be optimally guided over the electrode.

For this purpose, the sliding cap preferably has a deflection region for the guidance of the band.

Due to the angular contour of the main body of the electrode, a rotation protection of the sliding cap relative to the electrode can be ensured. As a result, an optimal guidance of the band is given in a further consequence.

The object according to the invention is also achieved by a spot welding gun as described above, having an electrode according to the abovementioned features.

In this case, the band is guided to protect the electrode around the contact surface of the electrode. 4 AT 503 310 B1

To protect the electrode, the band can also be passed over a sliding cap connected to the electrode.

The present invention will be explained in more detail with reference to the accompanying schematic drawings. 1 is a perspective view of a spot welding gun; 2 and 3 an embodiment of the electrode according to the invention in different views; 4 shows the arrangement of the electrode according to the invention on the electrode holder of a spot welding gun in an exploded view; Fig. 5 is a schematic view of an electrode attached to an electrode holder with a tape for protecting the electrode; Fig. 6 and 7, the spot welding gun with the electrode according to the invention positioned for and during a welding of sheet metal flanges; and FIG. 8 shows the welding point which results when the two sheets are welded together with the electrodes designed according to the invention.

By way of introduction, it is stated that identical parts of the exemplary embodiment are given the same reference numerals.

Fig. 1 shows a spot welding gun 1 for resistance welding of workpieces, in particular sheet metal flanges, in a perspective view, with only a half of the spot welding gun 1 was shown for clarity.

The spot welding gun 1 consists of a base body 2 and gun arms 3, on which electrode holders 4 and electrodes 5 are arranged. To protect the electrodes 5, a band 6 may be arranged accordingly. The belt 6 is unrolled by a winding device 7, which may preferably be arranged on the base body 2 but also on the gun arms 3 and guided along the Zangenarmgeometrie on the gun arm 3, the electrode holder 4 and the electrode 5 and opposite back to the winding device 7 ,

The electrode 5 is specially constructed for the use of a belt 6. On the electrode 5, a sliding cap 8 and a pressure element 9 can be arranged in the region of the electrode cap, which are connected in the longitudinal direction of the electrode 5 movable with this. The pressure element 9 exerts a force on the sliding cap 8. The sliding cap 8 and the pressure element 9 can have a guide for the band 6, so that the band 6 can be distanced from the electrode 5. The sliding cap 8 lifts the band 6 from the electrode surface of the electrode 5 during or after the opening of the spot welding gun 1. In contrast, the sliding cap 8 is pushed back during the welding process, so that the electrode 5 or the electrode surface comes to rest on the belt 6. When the spot welding gun 1 is closed, the electrodes 5 are pressed against the workpiece or sheets at a predefined pressure, and a specific electric current, which is supplied by a welding apparatus, is passed through the electrodes 5 to carry out the spot welding. Finally, the sheets are connected to each other via the welding spot 17 produced during the spot welding process. In addition, in the spot welding operation due to the pressure element 9, a pressure or a force exerted by the sliding cap 8 on the sheet, so that, for example, the process-related bending or buckling of the sheets is prevented. The use of such a spot welding gun 1 ensures that the band 6 does not come into direct contact with the electrode surface when the spot welding gun 1 is open, so that the band 6 can not rub against the electrode 5 during displacement. Thus, the life of the electrode 5 is significantly increased.

In order for the band 6 to be brought to the electrode 5, devices, in particular deflection rollers and sliding surfaces 10, for guiding and deflecting the band 6 are arranged on the forceps arm 3 and / or on the electrode holder 4. The belt 6 extends from a take-off roller 11 arranged in the winding device 11 via guide grooves 12 or a channel, the electrode holder 4 to the electrode 5 and from this in turn via the electrode holder 4 and via guide grooves 12 or a channel to a take-up roll 13, 5 AT 503 310 B1 which in turn is arranged in the winding device 7. The unwinding roller 11 and / or the winding roller 13 is coupled to a drive means 14, in particular an electronically controllable motor, so that a controlled displacement of the belt 6 is made possible by activation of the drive means 14.

The unwinding roller 11 and winding roller 13 is designed so that a simple and straightforward change or replacement of the rollers or the belt 6 can be made. In this case, the take-off reel 11 and the take-up reel 13 are mounted in the base body 2 or in the tong arm 3 in such a way that they can be easily exchanged, whereby an automatic coupling with the drive means 14 is produced when the take-off reel 11 and / or the take-up reel 13 are used. The arrangement of the unwinding rollers 11 and the take-up rollers 13 and the drive means 14 on the base body 2 or on the gun arms 3 ensures that easier access to the coils is ensured, thereby substantially simplifying and facilitating the replacement of the take-off reel 11 and take-up reel 13 becomes. Another positive effect of this arrangement of the take-off reel 11 and take-up reel 13 is that no disturbing elements or parts are present by the guidance of the belt 6 from the rear, ie from the main body 2 to the electrode 5, with the result that also For complex accessible workpieces a spot welding can be performed almost without problems, since there is no restriction on the accessibility to welding tongs without belt 6. By this configuration is also achieved that the size of the spot welding gun 1 can be kept low. The pliers arms 3 are adjustably mounted and can be adjusted by an actuating means 15, which may be formed for example by a servo motor or a gear 16. Thus, according to the described method, a spot welding of sheets, in particular sheet metal flanges, can be carried out. It should be noted that the welding point 17 is arranged as close as possible to the bending of the sheet metal flanges, as this reduces the material required for the welding point 17 of the sheet metal flanges.

FIGS. 2 and 3 show an electrode 5 according to the invention in various views. The electrode 5 has an eccentrically arranged contact surface 18, which has an elongated cross section, so that the material required for the welding point 17 of the sheets can be substantially reduced while maintaining the quality of welding. The electrode 5 may have a main body 19 with an edged contour, which merges into an electrode shaft 20.

The main body 19 preferably has four guide surfaces 21 to 24, thus has a floor plan. As a result, at least the width of the opposing guide surfaces 21 to 24 is identical. At the free end of the base body 19, ie the end which does not pass into the electrode shaft 20, there is the eccentrically arranged contact surface 18. The eccentric arrangement can be created by the base body 19 having an inclined surface 25 at the free end. Thus, the inclined surface 25 connects, for example, the guide surface 21 with the guide surface 23. The guide surface 21 is correspondingly higher than the guide surface 21 opposite guide surface 23. The eccentrically arranged contact surface 18 is disposed at that point of the base body 19, on which the guide surface 21 and the inclined surface 25 adjoin one another.

The preferred shape of the contact surface 18 is cut semi-circular in elevation. The substantially rounded corners of the main body 19 result in a cross section of the contact surface 18, which corresponds to a rectangle rounded at the corners or has an oval shape. This essentially results in an elliptical spot weld 17.

Of course, the transition from the inclined surface 25 to the guide surface 21, that is, the contact surface 18, are formed by a plane, which also substantially an elliptical spot weld 17 is formed. In this case, in particular an angular transition from the guide surface 21 to the plane is required, so that the band 6 is not damaged or worn in the guide 6 AT 503 310 B1 via the contact surface 18.

The electrode shaft 20 may have the shape of a cone, wherein the edged base body 19 preferably merges steplessly into the cone-shaped electrode shaft 20.

When carrying out a spot welding process, a correspondingly high current is conducted through the electrodes 5, as a result of which they heat up accordingly. For cooling the electrode 5, this can be provided with a bore 26 which ends in the main body 19 of the electrode 5. The bore 26 serves to receive a known from the prior art cooling device 27 and a cooling tube, which cools the electrodes 5, in particular their contact surfaces 18 accordingly.

From the exploded view of FIG. 4 is a compound of the electrode 5 according to the invention with an electrode holder 4 with the interposition of a pressure element 9 and using a sliding cap 8 can be seen. The pressure element 9, for example an elastomeric spring, receives the electrode shaft 20 of the electrode 5 in a corresponding recess 28. Preferably, the pressure element 9 also takes up a part of the main body 19 of the electrode 5. Accordingly, the recess 28 of the pressure member 9 is formed corresponding to the electrode 5 and has an edged upper portion corresponding to the shape of the main body 19 of the electrode 5 and a conical lower portion corresponding to the shape of the electrode shaft 20 of the electrode 5. Characterized in that the pressure element 9 receives a portion of the angular body 19, the pressure element 9 is rotatably connected to the electrode 5.

Likewise, the electrode 5 and the pressure element 9 rotatably connected to a possible electrode extension 29, which in turn is rotatably attached to the electrode holder 4. The cooling device 27 or the cooling tube is led through a corresponding bore through the electrode extension 29 to the electrode 5. Thus, the cooling device 27 can be received by the bore 26 of the electrode 5 and the contact surface 18 can be cooled.

The sliding cap 8 is preferably non-rotatably arranged on the base body 19 of the electrode 5, so that an optimal guidance of the belt 6 is ensured via the sliding cap 8. The torsion protection can be ensured by a recess 30 in the sliding cap 8, which is formed corresponding to the shape of the base body 19. For this purpose, the sliding cap 8 in the lower region on a sliding portion 31, which surrounds the example, four guide surfaces 21, 22, 23 and 24 of the base body 19 of the electrode 5 against rotation. The upper region of the sliding cap 8 may have a deflection region 32, which serves to guide the belt 6, so that it can be guided over the contact surface 18, as shown in FIG. 5, without danger of twisting.

By such a rotationally fixed arrangement of the electrode 5, the sliding cap 8, the pressure element 9, etc., it is ensured that the contact surface 18 does not change its predetermined position in the individual spot welding operations and thus the welding quality is not adversely affected.

In FIGS. 6 and 7, the electrode 5 according to the invention is shown in a spot welding of sheet metal flanges.

In Fig. 6, the electrodes 5 are positioned so that a sheet metal flange formed by two angled plates 33 and 34 can be welded. The angled plates 33 and 34 have a bend 35 and a flange with a certain width 36 (see Fig. 8).

The welding point 17 formed by the contact surface 18 of the electrodes 5 in the sheets 33, 34 should be as close as possible to the bend 35 of the sheet 33 or the sheet 34. This can be achieved by the eccentrically arranged contact surface 18 of the electrode 5. In the

Claims (20)

7 AT503 310 B1 As a result, the flange width 36 and the required material for the sheet metal flanges of the plates 33 and 34 can be significantly reduced. By this material savings and a small reduction in weight is achieved, which in sum, for example in a motor vehicle body, results in a considerable amount. Fig. 7 shows the electrodes 5 during a welding operation for connecting the sheets 33 and 34. Here, the method known from the prior art will not be discussed in more detail here. Rather, it is important here that the welding parameters, such as welding current and welding force, are not significantly limited by the design of the electrode 5 according to the invention. The welding point 17 shown in FIG. 8, which results in a welding operation with the electrode 5 according to the invention, illustrates the reduction of the required flange width 36 with respect to a circular electrode known from the prior art (indicated by dashed lines). It can clearly be seen that the welding spot 17 with the shape of a rectangle rounded off at the corners requires significantly less space than the circular spot weld shown in dashed lines. This would require a correspondingly larger, shown in broken lines, flange width 36. Likewise, the wear phenomena of the electrode 5 are kept to a minimum, since the guided around the electrode 5 belt 6 protects them accordingly. Thus, the life or the durability of the electrode 5 is substantially increased. Of course, it is still necessary to change the electrode 5 after a certain time. It is important in the attachment of the electrode 5 to the electrode extension 29 that the eccentrically arranged contact surface 18 has the correct position, that is as close as possible to the bend 35 of the sheets 33 and 34 is arranged. The correct position of the electrode 5 can be achieved, for example, by arranging on at least one of the guide surfaces 21, 22, 23 and / or 24 of the electrode 5 a groove, rail, nose, guide pin, etc. or the like. As a result, the electrode 5 can be mounted only in the correct position in the pressure element 9 according to which the contact surface 18 of the electrode 5 as close as possible to the bend 35 of the sheets 33 and 34 is arranged in the smallest possible flange width 36. Likewise, this can be done by appropriate markings on the electrode 5 and on the pressure element 9. Claims 1. An electrode (5) for spot welding sheets (33, 34), comprising a base body (19) having an electrode shaft (20) for placement in an electrode receptacle (4) and a surface (18) during the welding operation with the sheets (33, 34) comes into contact, characterized in that the contact surface (18) is elongated and arranged eccentrically. Second electrode (5) according to claim 1, characterized in that the base body (19), that is, the area below the eccentrically arranged contact surface (18), has an edged contour. 3. electrode (5) according to claim 2, characterized in that the edged contour of the base body (19) has four guide surfaces (21, 22, 23, 24). 4. electrode (5) according to claim 3, characterized in that two opposite guide surfaces (22, 24) aüfweisen substantially the same shape, and the contact surface (18) facing edges are formed by a slope. 8 AT 503 310 B1 5. electrode (5) according to claim 3 or 4, characterized in that two opposite guide surfaces (21, 23) are rectangular, the width of which is identical and the height is different. 6. electrode (5) according to claim 5, characterized in that the upper edge of that rectangular guide surface (21), which is higher than the opposite rectangular guide surface (23), with the contact surface (18) is connected. 7. electrode (5) according to claim 5 or 6, characterized in that the upper edge of that rectangular guide surface (23), which is lower than the opposite rectangular guide surface (21), by an inclined surface (25) with the contact surface (18). connected is. 8. electrode (5) according to one of claims 1 to 7, characterized in that the cut in elevation contact surface (18) is formed substantially half-round. 9. electrode (5) according to one of claims 1 to 8, characterized in that the cut in plan contact surface (18) is formed by the shape of a rounded at the corners rectangle. 10. electrode (5) according to one of claims 1 to 9, characterized in that the base body (19) of the electrode (5) merges into an electrode shaft (20), wherein the electrode shaft (20) is formed of a cone with a round cross-section , 11. electrode (5) according to one of claims 1 to 10, characterized in that the base body (19) has a bore (26) for receiving a cooling device (27). 12. Electrode (5) according to one of claims 3 to 11, characterized in that at least one guide surface (21, 22, 23, 24) at least one groove, rail or the like. Is arranged. 13. Electrode (5) according to one of claims 1 to 12, characterized in that with the main body (19) or electrode shaft (20), a pressure element (9) is preferably non-rotatably connected. 14. Electrode (5) according to claim 13, characterized in that the pressure element (9) has a recess (28) which is formed corresponding to the base body (19) or electrode shaft (20). 15. electrode (5) according to claim 13 or 14, characterized in that the pressure element (9) is formed by an elastomeric spring. 16. electrode (5) according to any one of claims 1 to 15, characterized in that in the region of the contact surface (18) has a sliding cap (8) for guiding a belt (6) is provided. 17. electrode (5) according to claim 16, characterized in that the sliding cap (8) has a deflection region (32) for the guidance of the belt (6). 18. spot welding gun (1) for resistance welding of sheets (33, 34), with pivotally mounted gun arms (3) with attached electrode holders (4) to which electrodes (5) are fixed, and with a take-off roller (11) and a Winding roller (13) comprising winding device (7) for winding and unwinding a tape (6) for protecting at least one electrode (5), characterized in that the electrode (5) is designed according to one of claims 1 to 17. 9 AT 503 310 B1 19. Spot welding gun (1) according to claim 18, characterized in that the band (6) is guided around the contact surface (18) of the electrode (5). 20. Spot welding gun (1) according to claim 19, characterized in that the band (6) via a with the electrode (5) connected to the sliding cap (8) is guided. For this purpose 6 sheets of drawings