EP0037329B1 - Tool for removing the electrodes in spot welding machines - Google Patents

Description

The present invention relates to welding electrodes for spot welding machines, each comprising an electrode tip mounted on an extension intended in turn to be fixed in an electrode holder of the spot welding machine. The tip is mounted on the extension and the extension in the electrode holder is provided by conical fitting.

During their use, the electrode tips are stressed both mechanically and electrically and that is why they must be replaced frequently. Although the extensions have a significantly longer lifespan, they are also subject to wear, while for some welding work it may be necessary to use different forms of extensions, so that one must be able to exchange them more or less frequently.

The replacement of tips and extensions is generally done using conventional tools such as ordinary pliers, wrenches or the like and is relatively easy and short work on simple welding machines having only one electrode and one counter electrode. However, it becomes long and tedious, even very difficult for multiple spot welding machines used more and more frequently in sheet metal workshops. Indeed, modern machines of this kind can include a large number of electrodes up to 60 for example, making as many welding spots on the same piece in a single work sequence. In addition, the electrodes can be mounted in places of the machine that are difficult to access. However, a machine working intensively may require replacing the electrode points approximately every week.

In addition, the force with which the points of electrode and the extensions must be disassembled, is considerable taking into account that the pressure exerted during welds and the effect of the electric current which crosses them, join them more and more solidly during the welding work.

The more specialized tools hitherto used for disassembly, for example pliers having spouts which deviate from one another, can in principle be used to disassemble the electrode parts, but they have the disadvantage apply spacing forces to these parts which do not act along their axis. The electrode parts then tend to get more wedged, which makes their disassembly even more difficult.

The object of the invention is therefore to provide a tool for dismantling the electrode parts of a welding machine, making it possible to efficiently perform the dismantling work in a minimum of time even in places which are difficult to access and even if the parts to be dismantled are held together with considerable force.

The invention therefore relates to a tool for disassembling electrode parts for spot welding machines, these parts being assembled by conical fitting, characterized in that it comprises a first block forming a slide on which a surface is defined. support intended to come into contact with an annular radial shoulder integral with one of the parts to be disassembled, a second block forming a slide on which a second bearing surface is defined intended to come into contact with an annular radial shoulder integral with the other part to be disassembled and parallel to the first bearing surface, the blocks respectively having two conjugate sliding surfaces extending obliquely relative to the parallel bearing surfaces and means for causing the relative movement of the blocks.

During the relative movement of the blocks, their bearing surfaces are thus spaced from one another while being kept parallel to each other so that the force applied to the parts to be disassembled is directed strictly along the axis of these parts. This prevents parts from sticking to each other. Furthermore, the tool in question has reduced dimensions and can easily be held with one hand. Its maneuverability thus allows disassembly even in places that are difficult to access of multiple point welding machines, the tool gripping the parts to be disassembled perpendicular to their axis.

• - la Fig. 1 est une vue en élévation et en coupe d'un outil suivant l'invention destiné au désassemblage d'une allonge et d'une pointe d'électrode;
• - la Fig. est une vue en perspective avec coupe partielle montrant en éclaté le même outil;
• - les Fig. 3 et 4 sont des vues analogues respectivement aux Fig. 1 et 2, montrant comment l'outil de l'invention peut être adapté pour le démontage d'allonges d'un porte-électrode.

Other advantages of the invention will become apparent during the description which follows, given solely by way of example and made with reference to the appended drawings, in which:

• - Fig. 1 is a view in elevation and in section of a tool according to the invention intended for the disassembly of an extension and an electrode tip;
• - Fig. is a perspective view with partial section exploded exploding the same tool;
• - Figs. 3 and 4 are views similar respectively to FIGS. 1 and 2, showing how the tool of the invention can be adapted for dismantling the extensions of an electrode holder.

In Fig. 1, we see partially represented an electrode assembly E composed of an extension A and a point P assembled by conical fitting by means of a frustoconical end-piece provided at the end of the extension A and fitting into a blind hole frustoconical b of the electrode tip P. This wears out during use and should therefore be replaced after a certain time. The set E defines an axis XX. In the example shown, the latter is vertical, but it is understood that it can - have any orientation in space n depending on the location of the assembly E in a welding machine.

Autor of the endpiece a is formed an annular radial shoulder c which is opposite another annular radial shoulder d formed by the rear end face of the electrode tip P.

The tool according to the invention comprises a first block 1 in the form of a rectangular parallelepiped and constituting a slide. It comprises a cavity 2 of U-shaped cross section having side walls 3, a rear wall 4 and a bottom 5 which is inclined from front to back with respect to the large upper and lower faces of the block 1. On the side opposite to the wall rear 3, the cavity is open to the outside.

The bottom 5 of the cavity 2 constitutes a sliding surface 6 which has a longitudinal notch 7 with a rounded bottom. On the side of the sliding surface 6 this notch has a rim 8 which follows its contour and which constitutes a first bearing surface 9 intended to come into contact with the annular shoulder c or d of the assembly e'electrode E .

The rear wall 4 is pierced with a threaded hole 10 into which is screwed a push rod 11 provided with a knurled handle 12, this assembly constituting a screw jack. Each side wall 3 has a rectilinear guide light 13 extending parallel to the sliding surface 6.

The tool also includes a second block 14 or slide which has the shape of a six-sided polyhedron, one of the large faces 16 (here the lower face) being inclined at an angle different from 90 ° relative to the small ones. faces of the block. The latter comprises a cavity 17 delimited by two parallel lateral walls 18, a rear wall 19 and a bottom 20. The latter has a very deep notch 21 thus forming by the rim 22 of this notch, a second bearing surface, the face oblique outer 16 constituting a second sliding surface. The rear wall 19 is pierced right through perpendicular to the side walls 18 by a hole 23 intended to receive a retaining pin 24, the ends of which can slide in the side slots 13 of the slide 1 and which is force-fitted into the slide. 14.

When the slide 14 is mounted in the slide 1 while being held by the pin 24, the respective bearing surfaces 9 and 22 extend in parallel, the obliquity of the sliding surfaces 6 and 16 in contact with one of the other being equal with respect to these bearing surfaces 9 and 22. Thus, when the slide 14 moves from back to front, the bearing surfaces 9 and 22 remain parallel, but deviate from one of the other, while still remaining pressed against the annular shoulders c and d of the electrode assembly E.

In other words, when an electrode assembly E is engaged in the notches 7 and 21, with the rim 8 and the bottom 20 placed in the annular groove between the two parts A and P of this assembly, a force rigorously axial (axis XX) separates these parts from one another, by the thrust which is exerted perpendicular to this axis by the rod 11 on the slide 14.

Furthermore, thanks to the fact that the spreading force is oriented axially, the parts cannot seize.

As the rod 11 works like a screw jack, the multiplication of the screwing effort is considerable and the separation of the parts can thus be carried out without any problem.

To further facilitate the separation of the electrode parts, it is possible to couple to the handle 12, a pneumatic or other drive device provided for example with a drive square which fits into a complementary bore 12a of the handle 12 Of course, the screw jack shown in Figs. 1 and 2 can be replaced by other types of motor devices such as pneumatic cylinders and others.

The tool shown in Figs. 3 and 4 is practically identical to the one just described. In this case, it is used to separate the extension A from the PE electrode holder roughly sketched out in FIG. 3 and in which is placed the conical shank e of the extension A. For this purpose, the tool is provided with an accessory constituted by a collar 26 which can be tightened on the extension A using a screw 27.

The slide 1 and the slide 14 of this tool have the following differences with the tool of FIGS. 1 and 2.

The notch 7 has no rim, while its large outer face corresponding to the bottom 5 of the cavity 2 constitutes a bearing surface 9A.

The slide 14 does not have side walls and therefore has the shape of a fork, the branches 28 of which define a second bearing surface 22A intended to come into contact with one of the faces cc of the collar 26, this face being the equivalent of the annular shoulder c of FIG. 1. The equivalent of the annular shoulder d of this same Fig. is here constituted by the end face d-d of the PE electrode holder on which the face 9A of the tool comes to bear.

It should be noted that the width of the collar 26 corresponds to the width of the cavity 2 of the slide so that it is also suitably guided in this slide during the disassembly of the electrode parts.

Claims (9)

1. Tool for disconnecting electrode elements for spot-welding machines, said elements being connected by a tapered fitting together, characterised in that it comprises a first block constituting a slide (1) on which is defined a bearing surface (9) for contacting an annular radial shouler (d; d-d) rigid with one of the elements (P) to be disconnected, a second block constituting a slideway (14) on which is defined a second bearing surface (22; 22A) for contacting an annular radial shoulder (c; c-c) rigid with the other element to be disconnected and parallel to the first bearing surface (9; 9A), the blocks having respectively two conjugate sliding surfaces (6, 16) which extend obliquely relative to the parallel bearing surfaces (9, 22; 9A, 22A) and means (11, 12) for producing the relative movement of the blocks (1, 14).

2. Tool according to claim 1, characterized in that the slide (1) and the slideway (14) each comprise a recess (7, 21) extending along the sliding surfaces (6, 16) and overlapping at least partly, recesses (7, 21) in which is adapted to engage said electrode assembly (E) so that the annular shoulders (c, c-c; d, d-d) are capable of being applied against the edges of said recesses which thus form said bearing surfaces (9; 9A, 22; 22A) and the sliding surfaces (6, 16) are located in an intermediate position between said bearing surfaces.

3. Tool according to claim 2, characterized in that said bearing surfaces (9, 22) are formed on edge portions along the contour of the respective recess (7, 21).

4. Tool according to claim 2, characterized in that at least one of the bearing surfaces (9A) is constituted by an outer surface of the corresponding block.

5. Tool according to any one of the claims 2 to 4, characterized in that said block forming a slideway (14) is disposed in a cavity (2) formed in the block constituting a slide (1) and on the bottom of which cavity is formed the sliding surface (6) of this slideway (14).

6. Tool according to claim 5, characterized in that said cavity (2) is defined by lateral walls (3) in each of which is formed an elongated opening (13) which extends parallel to the sliding surface (6) of the slide (1) and the slideway has extending therethrough a guide pin (24) which extends through the openings (13) of the walls (3) of the slide (1).

7. Tool according to any one of the claims 1 to 6, characterized in that said means producing the relative movement between the slide and the slideway comprise a screw jack (11, 12) associated, optionally, with driving means.

8. Tool according to any one of the preceding claims, characterized in that it comprises a collar

(26) adapted to be clamped on one of the elements (A) of an electrode assembly (E) and constituting by one of its radial surfaces one of the annular shoulders (c-c).

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