Welding device for resistance spot welding

Abstract

The invention relates to a welding device for resistance spot welding, comprising a welding electrode (3) and a counter-welding electrode (7). During the spot welding process, the two electrodes (3, 7) are in electrically conductive contact with the welding partners (9) to be welded, and welding spatter (20) is generated. According to the invention, the welding device comprises a tubular spatter guard (11) that shields the resulting welding spatter (20) from the process environment.

Description

The invention relates to a welding device for resistance spot welding according to the preamble of claim 1.A battery module for a high-voltage battery system usually has a module housing in which a battery cell stack is arranged. The housing components of the module housing are joined together in the prior art by laser beam welding. In contrast, resistance spot welding is more cost effective; however, spatter is produced. These can have a wide range of shapes and sizes. The spatters may possibly compromise the safety of the high-voltage battery system due to short circuits, insulation faults or the like. As such, the weld spatters must be removed from the module housing.CN 104 107 993 A discloses a spot welding device with a spot welding spray shield. This has a spring and a cylindrical protective sleeve which are arranged on an outer periphery of an electrode. DE 40 39 270 C1 discloses a splash guard for spot welding electrodes. Around the spot welding electrodes there is arranged a skirt which is electrically insulated from the latter and which is axially prestressed by a spring. DE 10 2013 225 727 A1 discloses a splash guard for welding caps. The splash guard is detachably fastened to a welding cap by means of a fastening device, wherein a collecting device serves for collecting spark flight and is arranged displaceably with respect to the fastening device.The object of the invention is to provide a welding device for resistance spot welding, in which the weld spatters that are produced can be removed from the welding partners to be welded in a structurally simple and reliable manner compared to the prior art.The object is achieved by the features of claim 1. Preferred developments of the invention are disclosed in the dependent claims.The invention is based on a welding device for resistance spot welding, which has a welding electrode and a counter-welding electrode. The two electrodes can be guided in a one-sided electrode arrangement in the same feed direction to the resistance spot weld (corresponds to a double-point butt welding). Alternatively, the two electrodes may be arranged in a two-sided electrode arrangement on opposite sides of the resistance spot weld. During the spot welding process, the two electrodes are in electrical contact with the welding partners to be welded at the resistance spot weld. In addition, spatter may be generated during the spot welding process. According to the characterizing part of claim 1, the welding device is equipped with an, in particular metallic, tubular splash guard, in particular a splash tube, in order to protect the process environment from spatter. The tubular splash guard shields the process environment from the resultant spatters. In an embodiment which is advantageous in terms of installation space, at least one of the two electrodes can be guided through the tubular splash guard in the region of the resistance spot weld.The welding device according to the invention can be used in particular in the production of a battery module for a high-voltage battery system. Such a battery module usually has a module housing in which a battery cell stack is arranged. The housing components of the module housing are welded by resistance spot welding with the aid of the welding device. The resultant spatters are caught by the tubular splash guard of the invention.In one technical implementation, the tubular splash guard can wrap the electrode at a radial distance. In addition, a first embodiment variant can be realized as follows: the tubular sprayer guard can be longitudinally adjustable with respect to the electrode by a stroke, namely between a sprayer guard position and a reversing position. In the spray protection position, the tubular spray protection is adjusted in the direction of the electrode end face, which can be brought into electrical contact with the welding partners. In contrast, in the reversing position, the tubular splash guard is reset by the stroke distance, so that the electrode end face is exposed to the outside. During the welding process, the tubular sprayer guard is in its sprayer guard position.For cleaning the inner side of the tubular sprayer guard, the welding device can have a scraping contour. In a cleaning process, the scraping contour can scrape off the spatters located on the inner side of the tubular splash guard. With regard to a cleaning process which is implemented in a simple manner from a manufacturing standpoint, the wiping off can take place directly when the tubular sprayer guard is reset into its reversing position. During the restoring movement, the scraping contour strips the weld sprays from the inner side of the tubular sprayer guard.In an alternative embodiment variant, the tubular sprayer protection can be coated on the inside with a removable protective film. This is acted upon by the weld sprays during the welding process. The protective film to which the spatters are applied can be removed from the tubular spatter protection as a sacrificial film after one or more welding processes. If necessary, the inside of the tubular sprayer guard can then be coated with a new protective film.With regard to a simple production of such a tubular sprayer guard from a manufacturing standpoint, the following production method can be used: Thus, the tubular sprayer guard can be formed from a planar, flexurally soft sprayer guard blank in which a carrier layer is coated with the protective film. The planar splash guard blank can be rolled up to form the tubular splash guard and subsequently inserted into a holder of the welding device.Alternatively and / or additionally, the welding device can have a suction device for removing the spatter generated during the welding process. This can be connected in terms of flow via a suction line to the inside of the tubular sprayer guard in order to suck away the resultant spatters.Alternatively and / or additionally, the welding device can be assigned a cleaning station in which the tubular sprayer protection contaminated with welding sprays can be cleaned. According to a first embodiment variant, the contaminated tubular sprayer guard can be treated with cold in the cleaning station. As a result, the weld sprays can chip from the (preferably metallic) tubular spray guard, specifically in particular on account of different thermal expansion coefficients of the tubular spray guard and the weld sprays. Alternatively, in the cleaning station, a mechanical cleaning of the tubular sprayer guard can be carried out by means of a brush.After completion of one or a predefined number of welding processes, the tubular sprayer guard contaminated with welding sprays can also be disposed of as scrap material and instead a new or cleaned tubular sprayer guard can be used.Exemplary embodiments of the invention are described below with reference to the attached figures.The following are shown: FIGS. 1 to 11 are different views illustrating the tubular splash guard according to the invention.In FIG. 1, a welding gun for resistance spot welding is indicated insofar as it is necessary for understanding the invention. Thus, the welding gun has an upper arm 1 to which a positive spot welding electrode 3 is mounted and a lower arm 5 to which a negative spot welding electrode 7 is mounted. A force generation, not shown, is assigned to the welding tongs, with the aid of which the two electrodes 3, 7 clamp the welding partners 9 to be joined together with a joining force during a welding process.In FIG. 1, the two electrodes 3, 7 are elongated in a pin-like or bolt-like manner. The upper electrode 3 is passed through a spray-catching pipe 11. The spray collecting tube 11 is mounted on a cylindrical guide means 13 so as to be longitudinally adjustable by a stroke h with respect to the electrode 3. For an easy displacement movement of the spray capture tube 11, the outer periphery of the guide means 13 is in sliding contact with the inner periphery of the spray capture tube 11 As can be further seen from the figures, the spray capture tube 11 is coaxial to the electrode 3 and is spaced apart therefrom by a radial distance r (FIG. 1 ).The spray collecting tube 11 is stroke-adjustable with respect to the upper electrode 3 between a spray protection position (FIG. 1 or 3 ) and a reversing position (FIG. 2 or 5 ) by the stroke h (FIG. 1 or 2 ). In the spray protection position (FIG. 1 or 3 ), the spray capture tube 11 is adjusted in the direction of the electrode end face. For tolerance compensation, the spray-catching tube 11 is spaced apart from the welding partners 9 in its spray-protection position over a small clearance a (FIG. 1 ), which are in electrical contact with the two electrodes 3, 7 during the welding process. In contrast, in the reversing position (FIG. 2 ), the spray collecting tube 11 is set back by the stroke h, so that the end face of the upper electrode 3 is exposed to the outside. In an alternative embodiment variant, the spray-catching tube 11 can also be resiliently in contact with the welding partners 9 in its spray-protection position, in order to enable tolerance compensation.The spot welding process (FIG. 3 ) is performed when the splash tube 11 is in its lower splash guard position. As a result, the process environment is protected by means of the splash tube 11 from spatters 20 which are produced in the spot welding process. The welding tips 20 hit the inside of the splash tube 11 during the spot welding process and remain adhered thereto (FIG. 3 ).After completion of the spot welding process, the spatters 20 are removed from the inside of the spatter collecting pipe 11. For this purpose, the spray collecting pipe 11 is displaced in a stroke in the direction of the reversing position (FIG. 5 ) in a reversing movement. The outer, cylindrical marginal edge 14 of the guide means 13 facing the resistance spot weld acts as a scraping contour which strips the weld sprays 20 from the inner side of the spray collecting pipe 11 (FIG. 5 ).Such a welding and cleaning process is indicated with reference to FIGS. 2 to 5. First, the upper electrode 3 is advanced toward the resistance spot weld to be manufactured in preparation for the welding process (FIG. 2 ). The spray collecting pipe 11 is still in its reversing position. The welding process then starts, in which the two electrodes 3, 7 sandwich the welding partners 9 with the joining force. The spray-catching tube 11 is in its spray-protection position (FIG. 3 ) from the start of the welding process in order to protect the process environment from the welding sprays 20 that are produced. After the welding process (FIG. 4 ) has taken place, the two electrodes 3, 7 are moved apart. The upper electrode 3 is transferred together with the spray collecting tube 11 still in the spray protection position into a cleaning station (FIG. 5 ). In the cleaning station, the spray collecting pipe 11 is returned with respect to the guide means 13 to its reversing position. As a result, the spatters 20 adhering to the inside of the splash tube 11 are scraped off and fall into a collecting container 15 (FIG. 5 ). The thus cleaned splash tube 11 is then usable for the next welding process.FIG. 6 shows a further exemplary embodiment in which the spray-collecting tube 11 and the upper electrode 3 form a structural unit which cannot be adjusted relative to one another. In this structural unit, the spray collecting tube 11 is connected in a fixed position to a holder 23, which is in turn fastened to the upper electrode 3. Whereas in the first exemplary embodiment the spray-trapping tube 11 is produced from metallic material, in the second exemplary embodiment the spray-trapping tube 11 can be formed from a planar, flexurally soft nonmetal blank 17 (FIG. 7 ), in which a carrier layer 19 is coated with a protective film 21.According to FIG. 7, the spray-collecting pipe 11 is produced by rolling up the planar nonmetal blank 17 (indicated by a rounded arrow). Then, the splash tube 11 is fixed into the holder 23 of the upper electrode 3. In the assembled state, the protective film 21 is located on the inner side of the splash tube 11. To remove the spatters 20, the protective film 21 can be removed from the carrier layer 19 as a sacrificial film.In a further variant embodiment (FIG. 8 ), the welding tongs can be assigned a suction device 25 which is in fluidic connection with the inside of the spray capture pipe 11 via a suction line 27. During the welding process, the suction direction 25 can at least partially suck off the resultant spatter 20.FIG. 9 shows a further exemplary embodiment in which a cleaning station is assigned to the welding tongs. In the cleaning station, the spray collecting pipe 11 contaminated with spatters 20 is treated with cold. As a result, the weld sprays 20 burst away from the spray gun 11 because of different thermal expansion coefficients of the metal spray gun 11 and the weld sprays 20.Alternatively, the cleaning process can also be carried out mechanically in the cleaning station, for example according to FIG. 10 by means of a brush 29. In a further embodiment variant, after completion of one or a predefined number of welding processes, the spray-catching tube 11 contaminated with the welding sprays 20 can be disposed of as scrap material and instead a cleaned or new spray-catching tube 11 can be installed in the welding tongs.In the preceding exemplary embodiments, the spray collecting pipe 11 according to the invention can be used in a welding gun whose electrodes 3, 7 are arranged in an electrode arrangement on both sides on mutually opposite sides of the welding partners 9, that is to say at the top and bottom. However, the invention is not limited to such a both-side electrode arrangement. Rather, the spray collecting tube 11 according to the invention can also be used in a one-sided electrode arrangement, as is indicated in FIG. 11. Accordingly, the two electrodes 3, 7 are arranged parallel next to one another and are surrounded jointly by the spray collecting tube 11. The two electrodes 3, 7 can be guided in the same feed direction to the resistance spot weld in order to carry out, for example, a double-point butt welding.LIST OF REFERENCE CHARACTERS:1 Upper welding gun arm 3 upper welding electrode 5 lower welding gun arm 7 lower welding electrode 9 welding partner 11 tubular splash guard / splash collector tube 13 guiding means 14 wiper contour 15 collecting container 17 blank 19 carrier layer 20 welding spatter 21 protective film 23 holder 25 suction direction 27 suction line 29 cleaning brush h stroke travel a clearance r radial distanceReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedCN 104 107 993 A

[0003] DE 40 39 270 C1

[0003] DE 10 2013 225 727 A1

[0003]

Claims

Welding device for resistance spot welding, having a welding electrode (3) and a counter-welding electrode (7) which are arranged in particular in a one-sided electrode arrangement or in a two-sided electrode arrangement at a resistance spot welding point, wherein during the spot welding process the two electrodes (3, 7) are in electrically conductive contact with welding partners (9) to be welded and weld spatters (20) are produced, characterized in that the welding device has an in particular metallic, tubular spatter protection (11), in particular a spatter trap tube, which shields the resultant weld spatters (20) from the process environment.Welding device according to claim 1, characterised in that the tubular sprayer guard (11) surrounds the electrode (3) at a radial distance (r), and / or that the tubular sprayer guard (11) is longitudinally adjustable with respect to the electrode (3) by a stroke (h), namely between a sprayer guard position, in which the tubular sprayer guard (11) is adjusted in the direction of the electrode end face, which can be brought into electrical contact with the welding partners (9), and a reversing position, in which the tubular sprayer guard (11) is set back by the stroke (h), so that the electrode end face is exposed to the outside, and that in particular during the welding process the tubular sprayer guard (11) is in its sprayer guard position.Welding device according to claim 1 or 2, characterised in that the welding device has a scraping contour (14), and in that in a cleaning process the scraping contour (14) scrapings off the welding sprays (20) located on the inner side of the tubular sprayer guard (11).Welding device according to claim 3, characterised in that the cleaning process takes place during a reversing movement of the tubular sprayer guard (11) into its reversing position, during which the scraping contour (14) scrapes the welding sprayers (20) from the inner side of the tubular sprayer guard (11).Welding device according to claim 1 or 2, characterised in that the tubular sprayer guard (11) is covered on the inside with a removable protective film (21), which can be acted upon by sprays (20) during the welding process, and in that, in particular for removing the sprays (20), the protective film (21) can be removed from the tubular sprayer guard (11) as a sacrificial film.Welding device according to claim 5, characterised in that the tubular sprayer guard (11) is positioned in a fixed position with respect to the electrode (3), and / or that the tubular sprayer guard (11) is formed from a planar, flexurally soft sprayer guard blank (17), in which a carrier layer (19) is coated with the protective film (21), and that the tubular sprayer guard (11) can be produced by rolling up the planar sprayer guard blank (17).Welding device according to one of the preceding claims, characterized in that, in order to remove the spatters (20) produced during the welding process, the welding device has a suction device (25) which is in pneumatic connection with the inner side of the tubular spatter guard (11) in order to suck away the spatters (20) produced.Welding device according to one of the preceding claims, characterized in that the welding device is assigned a cleaning station in which the tubular sprayer guard (11) contaminated with spatters (20) is treated with cold, as a result of which the spatters (20) burst off the tubular sprayer guard (11), specifically in particular on account of different coefficients of thermal expansion of the tubular sprayer guard (11) and the spatters (20), or in that in the cleaning station the tubular sprayer guard can be cleaned mechanically, for example by means of a brush (29).Welding device according to one of the preceding claims, characterized in that after completion of one or more welding processes, the tubular sprayer guard (11) contaminated with welding sprays (20) can be exchanged with a new or cleaned tubular sprayer guard (11).Use of a welding device according to one of the preceding claims for the assembly of a module housing of a battery module for a high-voltage battery system, in which housing components are joined to one another by means of resistance spot welding with the aid of the welding device.

Images