Welding device for resistance spot welding

Abstract

Welding device for resistance spot welding, comprising a welding electrode (3) and a counter-welding electrode (7) arranged in a single-sided electrode arrangement or in a double-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 spatter (20) is generated, characterized in that the welding device has a metallic, tubular spatter guard (11) which shields the generated weld spatter (20) from the process environment.

Description

[0001] The invention relates to a welding device for resistance spot welding according to the preamble of claim 1.

[0002] A battery module for a high-voltage battery system typically consists of a module housing containing a stack of battery cells. In the current state of the art, the housing components are joined by laser beam welding. While resistance spot welding is more cost-effective, it produces weld spatter. This spatter can exhibit a wide range of shapes and sizes. The weld spatter can potentially compromise the safety of the high-voltage battery system due to short circuits, insulation faults, or similar issues. Therefore, the weld spatter must be removed from the module housing.

[0003] A welding device of this type is known from KR 10 2011 0 051 595 A. A spot welding device with a spot welding splash guard is known from CN 1 04 107 993 A. This splash guard has a spring and a cylindrical protective sleeve arranged on the outer circumference of an electrode. A splash guard device for spot welding electrodes is known from DE 40 39 270 C1. An electrically insulated skirt is arranged around the spot welding electrodes and is axially pre-tensioned by a spring. A splash guard for welding caps is known from DE 10 2013 225 727 A1. The splash guard is detachably attached to a welding cap by means of a fastening device, wherein a collection device for collecting sparks is arranged to be slidable relative to the fastening device.

[0004] The object of the invention is to provide a welding device for resistance spot welding in which weld spatter can be removed from the welding partners to be welded in a structurally simple and operationally reliable manner compared to the prior art.

[0005] The problem is solved by the features of claim 1. Preferred embodiments of the invention are disclosed in the dependent claims.

[0006] The invention relates to a welding device for resistance spot welding, comprising a welding electrode and a counter-welding electrode. The two electrodes can be arranged in a single-sided electrode arrangement, guided in the same direction towards the resistance spot weld (corresponding to double-spot butt welding). Alternatively, the two electrodes can be arranged in a double-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 workpieces being welded at the resistance spot weld. Furthermore, weld spatter can be generated during the spot welding process. According to the characterizing part of claim 1, the welding device is equipped with a metallic, tubular spatter guard to protect the process environment from weld spatter.The tubular spatter guard shields the process environment from the resulting weld spatter. In a space-saving design, at least one of the two electrodes in the area of ​​the resistance spot weld can be guided through the tubular spatter guard.

[0007] The welding device according to the invention can be used in particular in the manufacture of a battery module for a high-voltage battery system. Such a battery module usually has a module housing in which a stack of battery cells is arranged. The housing components of the module housing are welded together using the welding device by resistance spot welding. The resulting weld spatter is captured by the tubular spatter guard according to the invention.

[0008] In one technical implementation, the tubular spatter guard can surround the electrode at a radial distance. Furthermore, a first design variant can be implemented as follows: The tubular spatter guard can be longitudinally adjustable relative to the electrode by one stroke, between a spatter guard position and a reversing position. In the spatter guard position, the tubular spatter guard is positioned towards the electrode face, which can be brought into electrical contact with the welding partners. Conversely, in the reversing position, the tubular spatter guard is retracted by the stroke, so that the electrode face is exposed. During the welding process, the tubular spatter guard remains in its spatter guard position.

[0009] To clean the inside of the tubular spatter guard, the welding device can have a wiper contour. During a cleaning process, the wiper contour can remove the weld spatter located on the inside of the tubular spatter guard. For a simple cleaning process in terms of manufacturing, the wiping can occur immediately when the tubular spatter guard is returned to its reverse position. During the return movement, the wiper contour removes the weld spatter from the inside of the tubular spatter guard.

[0010] In an alternative design, the tubular spatter guard can be lined on the inside with a removable protective film. This film is exposed to weld spatter during the welding process. After one or more welding cycles, the spatter-covered protective film can be removed from the tubular spatter guard, acting as a sacrificial layer. If necessary, the inside of the tubular spatter guard can then be relined with a new protective film.

[0011] With a view to the technically simple production of such a tubular splash guard, the following manufacturing method can be used: The tubular splash guard can be formed from a flat, flexible splash guard blank, in which a carrier layer is coated with the protective film. The flat splash guard blank can be rolled up to form the tubular splash guard and then inserted into a holder of the welding device.

[0012] Alternatively and / or additionally, the welding device can be equipped with an extraction system to remove the weld spatter generated during the welding process. This system can be connected to the inside of the tubular spatter guard via an extraction line to create a flow path for the weld spatter.

[0013] Alternatively and / or additionally, a cleaning station can be assigned to the welding device, in which the tubular spatter guard contaminated with weld spatter can be cleaned. According to a first embodiment, the contaminated tubular spatter guard can be treated with cold in the cleaning station. This causes the weld spatter to flake off the (preferably metallic) tubular spatter guard, particularly due to the different coefficients of thermal expansion of the tubular spatter guard and the weld spatter. Alternatively, the tubular spatter guard can be mechanically cleaned in the cleaning station using a brush.

[0014] After completion of one or a predefined number of welding processes, the tubular spatter guard contaminated with weld spatter can be disposed of as material waste and a new or cleaned tubular spatter guard can be used instead.

[0015] Exemplary embodiments of the invention are described below with reference to the accompanying figures.

[0016] They show: Fig. Figures 1 to 11 show different views illustrating the tubular splash guard according to the invention.

[0017] In the Fig. Figure 1 shows a welding gun for resistance spot welding, indicated to the extent necessary for understanding the invention. Accordingly, the welding gun has an upper arm 1, on which a positive spot welding electrode 3 is mounted, and a lower arm 5, on which a negative spot welding electrode 7 is mounted. The welding gun is associated with a force generator (not shown) by means of which the two electrodes 3, 7 clamp the welding partners 9 to be joined with a joining force during a welding process.

[0018] In the Fig. In Figure 1, the two electrodes 3 and 7 are elongated like pins or bolts. The upper electrode 3 is guided by a splash guard tube 11. The splash guard tube 11 is mounted on a cylindrical guide element 13 so that it can be adjusted longitudinally by a stroke h relative to the electrode 3. For smooth adjustment of the splash guard tube 11, the outer circumference of the guide element 13 is in sliding contact with the inner circumference of the splash guard tube 11. As can be further seen from the figures, the splash guard tube 11 is coaxial with the electrode 3 and has a radial distance r ( Fig. 1) away from it.

[0019] The splash guard tube 11 is positioned between a splash guard position with respect to the upper electrode 3 ( Fig. 1 or Fig. 3) and a reversing position ( Fig. 2 or Fig. 5) around the lifting distance h ( Fig. 1 or Fig. 2) Stroke adjustable. In the splash protection position ( Fig. 1 or Fig. 3) The splash guard tube 11 is adjusted towards the electrode face. To compensate for tolerances, the splash guard tube 11 in its splash guard position has a small clearance a ( Fig. 1) from the welding partners 9, which are in electrical contact with the two electrodes 3, 7 during the welding process. In contrast, in the reversing position ( Fig. 2) The spatter guard tube 11 is retracted by the stroke h so that the end face of the upper electrode 3 is exposed to the outside. In an alternative embodiment, the spatter guard tube 11 can also be spring-loaded in its spatter guard position in contact with the welding partners 9 to allow for tolerance compensation.

[0020] The spot welding process ( Fig. 3) is carried out when the spatter trap tube 11 is in its lower spatter protection position. This protects the process environment from weld spatter 20 generated during the spot welding process by means of the spatter trap tube 11. The weld spatter 20 strikes the inside of the spatter trap tube 11 during the spot welding process and adheres to it ( Fig. 3).

[0021] After completion of the spot welding process, the weld spatter 20 is removed from the inside of the spatter catcher tube 11. For this purpose, the spatter catcher tube 11 is reversed in the direction of the reversing position ( Fig. 5) stroke-adjusted. The outer, cylindrical edge 14 of the guide means 13 facing the resistance spot weld point acts as a wiper contour that wipes the weld spatter 20 from the inside of the spatter catcher tube 11 ( Fig. 5).

[0022] Based on the Fig. Figures 2 to 5 indicate such a welding and cleaning process. First, the upper electrode 3 is moved towards the resistance spot weld to be produced in preparation for the welding process ( Fig. 2) The spatter catcher 11 is still in its reversing position. The welding process then starts, during which the two electrodes 3, 7 clamp the welding partners 9 with the joining force. From the start of the welding process, the spatter catcher 11 is in its spatter protection position ( Fig. 3) to protect the process environment from weld spatter 20. After the welding process has been completed ( Fig. 4) The two electrodes 3, 7 are moved apart. The upper electrode 3, together with the splash guard tube 11, which is still in the splash guard position, is placed in a cleaning station ( Fig. 5) transferred. In the cleaning station, the spatter trap tube 11 is returned to its reverse position with reference to the guide element 13. This causes the weld spatter 20 adhering to the inside of the spatter trap tube 11 to be scraped off and fall into a collection container 15 ( Fig. 5) The spatter trap tube 11, cleaned in this way, can then be used for the next welding process.

[0023] In the Fig. Figure 6 shows a further embodiment in which the splash guard tube 11 and the upper electrode 3 form a fixed assembly. In this assembly, the splash guard tube 11 is fixedly connected to a bracket 23, which in turn is attached to the upper electrode 3. While in the first embodiment the splash guard tube 11 is made of metallic material, in the second embodiment the splash guard tube 11 can be made from a flat, flexible non-metallic blank 17 ( Fig. 7) is formed in which a carrier layer 19 is covered with a protective film 21.

[0024] According to the Fig. 7. The spatter trap tube 11 is produced by rolling up the flat non-metallic blank 17 (indicated by a rounded arrow). The spatter trap tube 11 is then attached to the holder 23 of the upper electrode 3. In the assembled state, the protective film 21 is located on the inside of the spatter trap tube 11. During the welding process, the protective film 21 is exposed to weld spatter 20. To remove the weld spatter 20, the protective film 21 can be peeled off the support layer 19 as a sacrificial film.

[0025] In another version ( Fig. 8) The welding gun can be equipped with an extraction device 25, which is in fluid-flow connection with the inside of the spatter trap tube 11 via a suction line 27. During the welding process, the extraction line 25 can at least partially extract the resulting weld spatter 20.

[0026] In the Fig. Figure 9 shows a further embodiment in which a cleaning station is associated with the welding gun. In the cleaning station, the spatter trap 11, contaminated with weld spatter 20, is treated with cold. This causes the weld spatter 20 to flake off the spatter trap 11 due to the different coefficients of thermal expansion of the metallic spatter trap 11 and the weld spatter 20. Therefore, it is preferred if the spatter trap 11 and the welding partners 9 are made of metallic materials with different coefficients of thermal expansion; for example, the welding partners 9 can be steel sheets, while the spatter trap 11 is an aluminum component.

[0027] Alternatively, the cleaning process in the cleaning station can also be mechanical, for example according to the Fig. 10 by means of a brush 29, can be carried out. In another embodiment, after completion of one or a predefined number of welding processes, the spatter trap tube 11 contaminated with the weld spatter 20 can be disposed of as material waste and a cleaned or new spatter trap tube 11 can be installed in the welding gun instead.

[0028] The spatter catcher tube 11 according to the invention is applicable in the preceding embodiments to a welding gun whose electrodes 3, 7 are arranged in a double-sided electrode arrangement on opposite sides of the welding partners 9, i.e., above and below. However, the invention is not limited to such a double-sided electrode arrangement. Rather, the spatter catcher tube 11 according to the invention can also be used with a single-sided electrode arrangement, as is the case in the Fig.As indicated in Figure 11, the two electrodes 3 and 7 are arranged parallel to each other and are both surrounded by the spatter catcher tube 11. The two electrodes 3 and 7 can be guided to the resistance spot welding point in the same direction, for example to perform a double spot butt welding. REFERENCE MARK LIST: 1 upper welding gun arm 3 upper welding electrode 5 lower welding gun arm 7 lower welding electrode 9 welding partners 11 tubular splash guards / splash guard tubes 13 Management tools 14 Wiper contour 15 collection containers 17 blanks 19 Carrier layer 20 weld spatters 21 Protective film 23 bracket 25 Extraction direction 27 Suction line 29 cleaning brush h Hubweg a free passage r radial spacing

Claims

[1] Welding device for resistance spot welding, comprising a welding electrode (3) and a counter-welding electrode (7) arranged in a single-sided electrode arrangement or in a double-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 spatter (20) is produced, characterized by , that the welding device has a metallic, tubular spatter guard (11) that shields the resulting weld spatter (20) from the process environment. [2] Welding device according to claim 1, characterized by, that the tubular spatter guard (11) surrounds the electrode (3) with radial distance (r), and / or that the tubular spatter guard (11) is longitudinally adjustable with respect to the electrode (3) by a stroke (h), namely between a spatter guard position in which the tubular spatter guard (11) is adjusted towards the electrode end face, which can be brought into electrical contact with the welding partner (9), and a reversing position in which the tubular spatter 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 spatter guard (11) is in its spatter guard position. [3] Welding device according to claim 1 or 2, characterized by, that the welding device has a wiping contour (14), and that in a cleaning process the wiping contour (14) wipes off the weld spatter (20) located on the inside of the tubular spatter guard (11). [4] Welding device according to claim 3, characterized by , that the cleaning process takes place during a reversing movement of the tubular splash guard (11) into its reversing position, during which the wiping contour (14) wipes the weld splashes (20) from the inside of the tubular splash guard (11). [5] Welding device according to claim 1 or 2, characterized by , that the tubular splash guard (11) is covered on the inside with a removable protective film (21) which can be exposed to welding splashes (20) during the welding process, and that, in particular for the removal of the welding splashes (20), the protective film (21) can be removed from the tubular splash guard (11) as a sacrificial film. [6] Welding device according to claim 5, characterized by , that the tubular splash guard (11) is positioned in a fixed location with respect to the electrode (3), and / or that the tubular splash guard (11) is formed from a flat, flexible splash guard blank (17) in which a carrier layer (19) is covered with the protective film (21), and that the tubular splash guard (11) can be produced by rolling up the flat splash guard blank (17). [7] Welding device according to one of the preceding claims, characterized by , that in order to remove the welding spatter (20) produced during the welding process the welding device has an extraction device (25) which is in pneumatic connection with the inside of the tubular spatter guard (11) in order to extract the welding spatter (20) produced. [8] Welding device according to one of the preceding claims, characterized by, that the welding device is assigned a cleaning station in which the tubular spatter guard (11) contaminated with weld spatter (20) is treated with cold, causing the weld spatter (20) to flake off the tubular spatter guard (11), in particular due to different coefficients of thermal expansion of the tubular spatter guard (11) and the weld spatter (20), or that the tubular spatter guard can be cleaned mechanically in the cleaning station, for example by means of a brush (29). [9] Welding apparatus according to any one of the preceding claims, characterized by , that after completion of one or more welding processes the tubular spatter guard (11) contaminated with weld spatter (20) can be replaced with a new or cleaned tubular spatter guard (11). [10] 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, wherein housing components are joined together by resistance spot welding using the welding device.

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