JP6049068B2 - Spot welding equipment - Google Patents

Description

  The present invention relates to a spot welding apparatus for welding a plurality of stacked metal plates (steel plates) with a pair of electrodes arranged coaxially and opposed to each other.

  As is well known, an automobile body is constituted by joining a plurality of steel plates by welding. As the welding method, direct spot welding using a C-type gun is generally employed from the viewpoint of cost and productivity, and most of the welds are formed by this direct spot welding. However, direct spot welding is a construction method in which a steel plate is energized while being pressed and clamped from both sides by a pair of electrodes of a C-type gun to form a welded portion, so that a hat-shaped section is formed on the steel plate on one side. A portion where the steel plate cannot be sandwiched cannot be welded, and there are some restrictions on the portion where the weld is formed.

  As a welding method in such a case, the technique described in Patent Document 1 is known. FIG. 8 shows a case where three steel plates 101, 102, 103 are overlapped and welded using the technique of Patent Document 1. As shown in the figure, a cross-sectional hat-shaped portion 103 a is formed on the steel plate 103. Of the steel plates 101 and 102, the portion covered with the hat-shaped portion 103 a of the steel plate 103 cannot be brought into contact with the second electrode 105 from below, so that the first electrode 104 and the second electrode 105 on the same axis are added. It cannot be energized and welded. Therefore, in the technique of Patent Document 1, as shown in FIG. 8, the two contact members 107 and 108 erected on the conductive member 106 at a predetermined interval are applied to the flange portion 103b of the steel plate 103 from below. After the contact, the first electrode 104 is brought into contact with the planned welding portion P from above, and the second electrode 105 is brought into contact with the conductive member 106 from below. By energizing between the electrodes 104 and 105 in this state, a current path of the first electrode 104 → the steel plate 101 and 102 → the flange portion 103b of the steel plate 103 → the contact member 108 → the conductive member 106 → the second electrode 105 is formed. A nugget is formed between the steel plates 101 and 102 directly under the first electrode 104 (the planned welding portion P), and resistance welding of both the steel plates 101 and 102 is performed.

JP 2008-246554 A

  By the way, when resistance welding is performed on a workpiece by a spot welding apparatus, in a mass production workpiece, a welding condition for forming an appropriate nugget at a site to be welded is examined before mass production. In general, the appropriate value of the current value and the applied pressure is examined. For example, in the case of a construction method using a welding apparatus in which a plurality of grounds (contact members) are set as in the spot welding apparatus disclosed in Patent Document 1, an appropriate energization path (contact member contact) is used. It is necessary to consider the contact position.

  In the welding apparatus of Patent Document 1, since the conductive member 106 and the contact members 107 and 108 can be moved integrally, the contact position between the contact members 107 and 108 and the steel plate 103 is changed by moving them. It is conceivable to set an appropriate energization path. However, in the technique of Patent Document 1, since the conductive member 106 and the contact members 107 and 108 are integrally provided, the formation of the energization path is unambiguous depending on the arrangement position of the contact members 107 and 108. Therefore, there is no room for examination such as selection of energization path, and there is a problem that it is very difficult to control energization. For this reason, an energization path through which an excessive current flows may be formed, and there is a problem that the welding scheduled portion P is burned out due to the excessive current.

  Moreover, although an appropriate welding condition can be obtained by providing a dedicated spot welding device corresponding to each workpiece, there is a problem that the equipment cost is very high, and it cannot be adopted.

  The present invention is obtained by improving and removing the above in view of the above problems, and does not provide a versatile spot welding apparatus capable of setting appropriate welding conditions even for workpieces of various shapes. It is what.

  In order to solve the above-mentioned problems, the spot welding apparatus employed by the present invention includes a pair of electrodes that are coaxially opposed to each other and are capable of approaching and separating, and a plurality of conductive members disposed on one side of the workpiece. An abutting member connected to the conductive member so as to be energized, the abutting member abutting against the work from one side, one electrode abutting against the conductive member, and the other electrode A spot welding device that abuts a welding target portion of a workpiece from the other side and energizes between the pair of electrodes in this state to weld the planned welding portion, wherein the plurality of conductive members are electrically connected And a conductive means capable of switching between a conductive state electrically connected to and a non-conductive state electrically blocking the plurality of conductive members.

  As described above, in the spot welding apparatus of the present invention, there is provided a conduction means capable of switching between a conductive state in which a plurality of conductive members are electrically connected and a non-conductive state in which the plurality of conductive members are electrically blocked. . As a result, even when a suitable energization path cannot be formed by changing the contact position of the abutment member with respect to the workpiece, a more appropriate energization path can be obtained by selectively switching the conduction state between the plurality of conductive members by the conduction means. It is possible to make a selection. Therefore, it is possible to provide a versatile spot welding apparatus that expands the options for diversion control and can determine welding conditions for various workpiece shapes.

  In the above spot welding apparatus, if a plurality of contact members are provided and can be individually moved up and down, only the required contact members can be selectively brought into contact with the steel plate. This further expands the options for diversion control and makes it easier to form an appropriate energization path.

  As described above, according to the spot welding apparatus of the present invention, by switching the conduction state between the plurality of conductive members by the conduction means, the options for the diversion control are expanded, and energization paths corresponding to various workpiece shapes are formed. Therefore, it is possible to form a spot welded portion without causing burnout or the like.

3 is a cross-sectional perspective view of a workpiece W. FIG. It is a top view of the spot welding apparatus which concerns on embodiment of this invention. It is the side view which looked at the spot welding apparatus of FIG. 2 from the III-III line. It is a side view of a conduction means. It is a side view of the said spot welding apparatus (at the time of a work set). It is a top view of the said spot welding apparatus (at the time of welding execution). It is a side view of the said spot welding apparatus (at the time of welding execution). It is a side view of the conventional spot welding apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The spot welding apparatus 1 according to the embodiment of the present invention performs welding on, for example, a planned welding portion P of a workpiece W shown in FIG. The workpiece W is a long frame member having a substantially L shape in plan view (see FIG. 2). The workpiece W includes two substantially flat steel plates W1 and W2, and a steel plate W3 having a cross-sectional hat shape that is overlapped on one side thereof (downward in the drawing). The steel plate W3 has a hat portion H and flange portions F provided on both sides thereof. The steel plates W1 to W3 are integrated by performing direct spot welding at a plurality of locations separated in the longitudinal direction of the flange portion F in advance. The spot welding apparatus 1 is capable of welding the planned welding portion P covered with the hat portion H of the steel plate W3 from one side of the steel plates 1 and 2.

  As shown in FIGS. 2 and 3, the spot welding apparatus 1 is a welding gun having a work set base 2, a conductive member, a contact member 4, a drive unit 5, a connecting unit 6, and electrodes 7 a and 7 b. (Refer FIG. 8) and the conduction means 8 are mainly provided.

  The work set base 2 is formed by combining a plurality of metal frames, for example, and is installed on the floor surface. The work set base 2 includes a placement portion 2a on which the work W is placed and a clamp member 2b. The placement portion 2a is provided at a position where the flange portion F of the workpiece W can be supported from below. The clamp member 2b fixes the work W to the work set base 2 by sandwiching the work W in cooperation with the placement portion 2a. In the present embodiment, the clamp member 2b is rotatable around the pin 2c, and the pressing portion 2d is provided at a position corresponding to the placement portion 2a.

  The conductive member is made of a conductive material (for example, metal, particularly copper), and is divided into a plurality of parts. In the present embodiment, conductive plates 3a, 3b, and 3c are provided as a plurality of conductive members (see FIG. 2). The conductive plates 3a, 3b, 3c are provided apart from each other, and are fixed to the work set base 2 via insulating members (not shown), respectively.

  Conductive means 8 are provided between the conductive plates 3a and 3b, between the conductive plates 3b and 3c, and between the conductive plates 3c and 3a, respectively. The conduction means 8 switches between a conduction state in which the two conductive plates are electrically conducted and a non-conduction state in which the two conductive plates are electrically cut off. As shown in FIG. 4, the conduction means 8 of this embodiment includes a terminal member 8a made of a conductive material (for example, metal, particularly copper), and a cylinder 8b that drives the terminal member 8a up and down. The terminal member 8a in the illustrated example integrally includes a pair of contact portions 8a1 and 8a2 that respectively contact two conductive plates and a connection portion 8a3 that connects the pair of contact portions 8a1 and 8a2. By projecting the cylinder 8b and bringing the contact portions 8a1 and 8a2 of the terminal member 8a into contact with two conductive plates (conductive plates 3a and 3b in the illustrated example), these conductive plates 3a and 3b are electrically connected. (See the dotted line in the figure). On the other hand, by retracting the cylinder 8b to separate the terminal member 8a from the two conductive plates 3a and 3b, the conductive plates 3a and 3c are electrically disconnected (see a solid line in the figure). The conduction means 8 provided between the conductive plates 3b and 3c and between the conductive plates 3a and 3c has the same configuration. Moreover, each conduction | electrical_connection means 8 can switch a conduction | electrical_connection state independently, respectively, In this embodiment, the cylinder 8b of each conduction | electrical_connection means 8 can be raised / lowered separately.

  The contact member 4 is disposed at a position where it can contact the flange portion F of the workpiece W from below. In this embodiment, the contact member 4 is provided at a plurality of locations. Specifically, as shown in FIG. 2, two contact members 4 are connected to each of the conductive plates 3a and 3c, and one contact member 4 is connected to the conductive plate 3b. The contact member 4 is movable between a contact position that contacts the workpiece W (see the dotted line in FIG. 3) and a retracted position that is separated from the workpiece W (see the solid line in FIG. 3). It can be moved up and down in the direction. The contact member 4 includes an axial main body 4a extending in the vertical direction, and a tip 4b provided at the tip (upper end in the figure) of the main body 4a. Both the main body 4a and the chip 4b are made of metal.

  The drive unit 5 drives the contact member 4 between the contact position and the retracted position. In this embodiment, the drive part 5 is connected to the lower end of each contact member 4, and each contact member 4 is driven up and down individually. The drive unit 5 is composed of, for example, a cylinder (air cylinder or hydraulic cylinder). In addition, the drive unit 5 may be constituted by a servo motor, a ball screw, or the like. The drive unit 5 is fixed to the work set base 2. An insulating member (not shown) is provided between each contact member 4 and each drive unit 5, thereby insulating both.

  The conductive plates 3a to 3c and each contact member 4 are connected by a connecting portion 6 so as to be energized. The connecting portion 6 allows the contact member 4 to move up and down while maintaining the energization between the conductive plates 3 a to 3 c and the contact member 4. In this embodiment, the connection part 6 is comprised by the substantially U-shaped elastic member (for example, laminated metal plate), and raising / lowering of the contact member 4 is accept | permitted because the connection part 6 curves (refer the dotted line of FIG. 3). ).

  The welding gun has a first electrode 7a and a second electrode 7b (see FIG. 7). Both the electrodes 7a and 7b are arranged on the same axis so as to be close to and away from each other. Both electrodes 7a and 7b are connected to a robot arm via a gun yoke (not shown). Each of the electrodes 7a and 7b has shaft-shaped main body portions 7a1 and 7b1 and tips 7a2 and 7b2 provided at the tips thereof.

  Hereinafter, a procedure for performing welding on the workpiece W using the spot welding apparatus will be described.

  First, as shown in FIG. 5, the workpiece W is placed on the placement portion 2a of the work set base 2 with the tip of the clamp member 2b retracted upward and the pressing portion 2d is separated from the placement portion 2a. (See arrow C). By placing the flange portion F of the workpiece W on the placement portion 2a with the hat portion H of the steel plate W3 protruding downward, the hat portion H is disposed between the plurality of contact members 4. In this state, the clamp member 2b of the work set base 2 is rotated (see arrow D), and the work W is moved by holding the flange portion F of the work W from above and below by the pressing portion 2d and the placement portion 2a. Set on set base 2.

  At this time, the conduction state between the conductive plates 3a, 3b, and 3c is set by each conduction means 8. In the present embodiment, the terminal member 8a of the conduction means 8 between the conductive plates 3a and 3b is retracted to bring the conductive plates 3a and 3b into a non-conductive state (see FIG. 5), and the conductive plates 3a and 3c. The terminal members 8a of the conduction means 8 between the conductive plates 3b and 3c are brought into contact with the respective conductive plates, and the conductive plates 3a and 3c and the conductive plates 3b and 3c are brought into a conductive state, respectively. In FIG. 6, the conductive means 8 in the conductive state is indicated by a solid line, and the conductive means 8 in the non-conductive state is indicated by a dotted line.

  Next, the abutting member 4 is raised by the drive unit 5 and is brought into contact with the flange portion F of the workpiece W from below (see the dotted line in FIG. 3). In the present embodiment, the contact member 4 is brought into contact with a previously welded portion of the flange portion F of the workpiece W. Thereby, the contact member 4 functions as a ground electrode. At this time, since each contact member 4 is driven by a separate drive unit 5, each contact member 4 can be raised and brought into contact with the workpiece W reliably. Further, in order to form a desired energization path, only a part of the abutting members 4 can be raised and brought into contact with the workpiece W. In addition, since the pressing force can be set individually for each abutting member 4, the pressing force can be varied for each abutting member 4, or the pressing force for all the abutting members 4 can be equalized. it can.

  Thereafter, the welding gun is moved by the robot arm, and as shown in FIG. 7, the hat portion H of the work W and the conductive member (conductive plate 3b in the illustrated example) are arranged between the first electrode 7a and the second electrode 7b. Let Then, the first electrode 7a is brought into contact with the planned welding portion P of the workpiece W from above, and the second electrode 7b is brought into contact with the conductive plate 3b from below. In this state, the work W and the conductive plate 3b are sandwiched and pressurized by both the electrodes 7a and 7b, and electricity is applied between the electrodes 7a and 7b. As a result, an energization path of the first electrode 7a → the workpiece W → the contact member 4 → the connecting portion 6 → the conductive plate → the second electrode 7b is formed, and welding is applied to the planned welding portion P of the workpiece W.

  The energization path at this time will be described in detail. First, a current flows from the first electrode 7a to the nearest contact member 4 via the workpiece W (see arrow Q1). Then, a current flows from the contact member 4 to the conductive plate 3 a via the connecting portion 6. At this time, the conductive plate 3a and the conductive plate 3b are in a non-conductive state by the conductive means 8, and the conductive plate 3a and the conductive plate 3c, and the conductive plate 3b and the conductive plate 3c are conductive by the conductive means 8, respectively. It is in a state. As a result, the current flows through the path of the conductive plate 3a → the conductive plate 3c → the conductive plate 3b and reaches the second electrode 7b (see arrow Q2). In this way, by appropriately switching the energization state between the conductive plates 3a to 3c by the conduction means 8, the energization path through the conductive plates 3a to 3c can be changed. Therefore, when the value of the current flowing in the planned welding location is large, by switching the conduction means 8 so that the energization path becomes long as in the present embodiment, appropriate welding conditions can be obtained without changing the position of the contact member 4. Can be set.

  Moreover, in this embodiment, since each contact member 4 is individually driven up and down, a part of the plurality of contact members 4 can be brought into contact with the workpiece. Thus, since the energization path can be changed by appropriately selecting the abutting member 4 that abuts on the workpiece W, more appropriate welding conditions can be set.

  When the welding to one place to be welded P is completed, the electrodes 7a and 7b are separated to release the pressure applied to the workpiece W and the conductive plate 3b. Then, the welding head is moved to the next scheduled welding portion by the robot arm, and welding is performed in the same procedure as described above. At this time, if necessary, the conduction state of each conduction means 8 is switched to form a desired energization path through part or all of the conductive plates 3a to 3c. When the welding to all the planned welding portions P is completed, the drive member 5 lowers the contact member 4 to the retracted position, and the clamp member 2b is rotated to release the clamp of the workpiece W, and then the workpiece W is spot welded. Unload from the device 1.

  The present invention is not limited to the embodiment described above, and appropriate modifications are possible. For example, if the energization resistance of the terminal member 8a of the conducting means 8 is increased, the resistance of the energization path through the terminal member 8a can be increased. In this case, by increasing the number of terminal members 8a through which the energization path passes, the resistance value of the entire energization path can be greatly increased, so that the range of setting of the welding conditions is further expanded. As means for increasing the energization resistance, it is conceivable to reduce the cross-sectional area of the terminal member 8a or to form the terminal member 8a with a material having a high resistance value (for example, tungsten).

  In addition, the number and arrangement positions of the contact members, the number of divided conductive members, the shape, and the like may be set so that the welding current path is appropriate according to the type of workpiece and the welding site.

DESCRIPTION OF SYMBOLS 1 Spot welding apparatus 2 Work set bases 3a-3c Conductive plate (conductive member)
4 Contact member 5 Drive part 6 Connection part 7a, 7b Electrode 8 Conducting means 8a Terminal member 8b Cylinder

Claims (1)

A pair of electrodes disposed on the same axis and arranged to be close to and away from each other, a plurality of conductive members disposed on one side of the workpiece, and a contact member connected to the conductive member so as to be energized. The contact member is brought into contact with the work from one side, one electrode is brought into contact with the conductive member, and the other electrode is brought into contact with the planned welding portion of the work from the other side. A spot welding apparatus that welds the welded portion by energizing between a pair of electrodes,
A spot welding apparatus provided with conduction means capable of switching between a conduction state in which the plurality of conductive members are electrically conducted and a non-conduction state in which the plurality of conductive members are electrically cut off.

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