JP2014083585A - Spot welding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spot welding device capable of obtaining a good welding part with sputter-less.SOLUTION: A spot welding device 1 performs welding of a weld-planned part P by clamping a work-piece W by a clamp means 20 which clamps the work-piece W, bringing a second electrode 7b into contact with a conductive member 3 while bringing a contact member 4 into contact with the work-piece W from one side, bringing a first electrode 7a into contact with the weld-planned part P of the work-piece W from the other side, and then performing electric conduction between the first electrode 7a and the second electrode 7b in such a state as said above. In the spot welding device 1, the weld-planned part P is positioned in a region R of the work-piece W surrounded by a part Wa to be clamped which is clamped by the clamp means 20.

Description

  The present invention relates to a spot welding apparatus.

  The spot welding method is highly used in production of automobile bodies, for example, because of its high productivity and low manufacturing costs. In a general spot welding method, a welding gun having a C-shaped gun yoke having a pair of electrodes arranged opposite to each other is used. Specifically, after moving the welding gun attached to the robot arm or the like to a position where the workpiece is placed between the pair of electrodes, the workpiece is clamped with the pair of electrodes and pressurized with a predetermined pressure. However, welding is performed by energizing between the pair of electrodes.

  However, as shown in FIG. 1, for example, when one side of the planned welding portion is covered with a metal plate W3 having a cross-sectional hat shape, the welding planned portion and the top surface (lower surface in the drawing) of the hat portion are covered with a pair of electrodes. If it is clamped with a welding gun, the top surface of the hat may be deformed. Therefore, it may not be possible to clamp with a welding gun.

  In order to avoid such problems, for example, a spot welding apparatus as shown in Patent Document 1 below has been proposed. This welding apparatus includes a conduction means including a conductive member provided on one side of the hat portion and a pair of contact members protruding from the conductive member toward the workpiece. The first electrode is brought into contact with the work from the other side with the pair of contact members being in contact with the work from one side at a position avoiding the hat portion. Further, the work is clamped by bringing the second electrode into contact with the conductive member from one side. In this state, welding is performed by energizing between the pair of electrodes. According to this welding apparatus, since the hat portion is not directly clamped by the pair of electrodes, deformation of the hat portion can be avoided.

JP 2008-246554 A

  In the spot welding apparatus of Patent Document 1, prior to clamping the work by the first electrode and the second electrode, the conduction means (conductive member and contact member) having a pair of contact members is used as the second electrode and the work. Intervene between. The tip of the abutting member is brought into contact with the workpiece, the first electrode is brought into contact with the welding target position of the workpiece, and the second electrode is brought into contact with the conductive member of the conduction means. Thereby, the welding target position of the workpiece is clamped by the first electrode and the second electrode via the conduction means.

  However, when welding is performed via the conductive means, the electrodes cannot be placed directly opposite to the workpiece, so that a large pressing force cannot be applied. Therefore, the pressing force for clamping the workpiece must be set to such an extent that the workpiece is not deformed, and there is a possibility that a gap is generated between the workpieces due to insufficient pressing force. As a result, there is a problem that spatter occurs due to the work being melted and scattered. Further, since the other side of the workpiece is pressed only by the first electrode, when changing the welding position, the position of the workpiece may change if the first electrode is separated to release the pressing of the workpiece. There is also.

  An object of this invention is to provide the spot welding apparatus which can obtain the favorable weld part which a spatter does not produce even if it is a C-type welding apparatus using a conductive member.

  In order to achieve the above object, the present invention provides a first electrode and a second electrode that are arranged on the same axis and are opposed to each other, a conductive member disposed on one side of a workpiece, a conductive member A contact member connected to the member so as to be energized; a drive unit that drives the contact member between a contact position that contacts the workpiece and a retracted position that does not contact the workpiece; and a clamping unit that clamps the workpiece The contact member is brought into contact with the workpiece from one side, the second electrode is brought into contact with the conductive member, and the first electrode is brought into contact with the planned welding portion of the workpiece from the other side. A spot welding apparatus that welds a welding target portion by energizing between a first electrode and a second electrode, and is scheduled to be welded to a region surrounded by a clamped portion clamped by a clamping means in a workpiece. Specially placed To.

  With the above configuration, when the workpiece is clamped by the clamping means, the workpiece is clamped, that is, the clamped portion is arranged so as to surround the planned welding portion, so that it is surrounded by the clamped position. In the region, a state in which the workpieces are in close contact with each other is formed. Therefore, even when the electrodes cannot be disposed directly opposite to the workpiece, the gap between the workpieces in the planned welding portion can be filled. Also, when welding a plurality of locations, even if the first electrode and the second electrode are separated from each other, the workpiece can be held at a predetermined position by the clamping means. Therefore, even if the first electrode and the second electrode are separated, the workpiece Therefore, the welding position can be accurately welded to a predetermined position.

  Further, in the above spot welding apparatus, if a clamper part capable of clamping a plurality of positions of a workpiece with one clamp driving part is provided, the number of clamping means can be reduced, so that the welding apparatus can be reduced in size and Cost reduction can be achieved.

  As described above, according to the spot welding apparatus of the present invention, a good weld can be obtained even with a C-type welding apparatus using a conductive member.

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 a side view of the said spot welding apparatus. It is sectional drawing of a contact member. It is a side view of the said spot welding apparatus (at the time of a work set). It is a side view of the said spot welding apparatus (at the time of welding execution).

  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 work W is a long frame member, and includes two substantially flat metal plates W1 and W2 and a hat-shaped metal plate W3 stacked on one side (downward in the drawing). . A hollow cylindrical portion is formed by the hat portion H of the metal plate W3 and the metal plates W1 and W2, and a flange portion F is provided that protrudes on both sides of the cylindrical portion and overlaps the three metal plates W1 to W3. It is done. The workpiece W is integrated by welding at a plurality of locations of the flange portion F in advance. The planned welding portion P is covered with a hat portion H of the metal plate W3 from one side.

  As shown in FIGS. 2 and 3, the spot welding apparatus 1 includes a work set base 2, a conductive member 3, a contact member 4, a drive unit 5, a connecting unit 6, a welding gun (not shown), It has. The work set base 2 is provided with a clamping means 20 for clamping the work.

  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 is integrally provided with clamping means 20 for clamping the work W. The clamp unit 20 includes a clamp member 22 having a clamper unit 21 for clamping the workpiece W, a pin 2c that rotatably supports the clamp member 22, and a clamper drive unit (not shown) that drives the clamp unit 20. It consists of The clamp means 20 fixes the workpiece W to the placement portion 2a by clamping the workpiece W in cooperation with the placement portion 2a. In this embodiment, the clamp means 20 stably fixes the workpiece W. 2, the positions where the workpiece W is clamped by the placing portion 2a and the clamper portion 21, that is, the clamped portions Wa are three or more (four in the illustrated example). Further, at least one (three in the illustrated example) planned welding portion P is disposed in the region R surrounded by the clamped portion Wa (see FIG. 2). Specifically, as shown in FIG. 2, clamp means 20 are provided at a plurality of locations (two locations in the illustrated example) spaced apart in the longitudinal direction of the workpiece, and a plurality of clamp members 22 of each clamp means 20 (see FIG. 2). Two clamper portions 21 are provided in the illustrated example. The flange portions F on both sides of the hat portion H of the workpiece W can be clamped at a time. Each clamp means 20 is provided with a clamp drive section (not shown). Thereby, by driving one clamp drive part, the several clamper part 21 provided in the clamp member 22 can be driven simultaneously, Therefore Size reduction and cost reduction of an apparatus can be achieved. Moreover, since both the flange parts F can be clamped at once with one clamp member 22, the workpiece can be securely fixed.

  The conductive member 3 is fixed to the work set base 2. The conductive member 3 has a horizontal portion 3a and an inclined portion 3b made of a flat metal plate. The horizontal portion 3a has a substantially L shape in plan view, and the inclined portion 3b has a substantially U shape in plan view (see FIG. 2). The horizontal part 3a and the inclined part 3b are fixed in a state where electricity can be applied. The inclined portion 3 b is parallel to the planned welding portion P of the workpiece W held on the workpiece set base 2. In the example of illustration, the part which covers the opening part of the hat part H among the metal plates W1 and W2 of the workpiece | work W and the inclination part 3b of the electrically-conductive member 3 are parallel.

  The conductive member 3 is formed with an insertion portion through which the contact member 4 can be inserted. In the present embodiment, as shown in FIG. 2, the insertion portions 3 c and 3 d are formed at a plurality of locations (two locations in the illustrated example) of the conductive member 3. In the illustrated example, the insertion portions 3c and 3d respectively penetrate the conductive member 3 in the vertical direction (that is, the moving direction of the contact member 4) and in the horizontal direction (that is, the direction orthogonal to the moving direction of the contact member 4). Is open. One insertion part 3c is comprised by the recessed part formed in the substantially U-shaped inclination part 3b. The other insertion portion 3d is configured by a recess formed by a substantially L-shaped horizontal portion 3a and an inclined portion 3b. Thus, by arranging the contact member 4 on the inner periphery of the insertion portions 3c and 3d provided in the conductive member 3, for example, compared to the case where the conductive member 3 and the contact member 4 are arranged in the horizontal direction, for example. The space for arranging these members can be reduced to reduce the size of the spot welding apparatus 1.

  The contact member 4 is disposed at a position where it can contact the flange portion F of the workpiece W from below. In the present embodiment, the contact members 4 are provided at a plurality of locations. In the illustrated example, the contact members 4 are provided below the two contact members 4 arranged along one flange portion F and the other flange portion F. One contact member 4 is provided. 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. As shown in FIG. 4, both are fixed by taper-fitting a tapered shank 4a1 provided at the front end of the main body 4a and a tapered fitting hole 4b1 provided in the chip 4b. .

  In the present embodiment, as described above, the contact member 4 is disposed on the inner periphery of the insertion portions 3 c and 3 d of the conductive member 3 in order to reduce the arrangement space of the conductive member 3 and the contact member 4. For example, when a through hole is provided in the conductive member 3 as an insertion portion and the contact member 4 is inserted into the inner periphery thereof, the arrangement space of both members can be reduced. However, in this case, at the time of maintenance of the chip 4b, the conductive member 3 becomes in the way and it becomes difficult to access the contact member 4, and there is a possibility that work efficiency of confirmation and replacement of the chip 4b is lowered. Therefore, as shown in FIGS. 2 and 3, if the insertion portions 3c and 3d of the conductive member 3 are opened in the horizontal direction, the contact member 4 can be accessed from the opening side of the insertion portions 3c and 3d. Work efficiency is improved. In particular, when a plurality of insertion portions 3c and 3d are provided as shown in the figure, if the opening directions of the insertion portions 3c and 3d are unified, the contact member 4 disposed on the inner periphery of the plurality of insertion portions 3c and 3d. Can be accessed from the same direction. Thereby, since the operator can access all the contact members 4 from the opening side (upper side of FIG. 1) of the insertion parts 3c and 3d, work efficiency is further improved.

  A cooling water channel is provided inside the main body 4a. Specifically, as shown in FIG. 4, an axial hole 4a2 opened at the tip of the shank 4a1 is formed in the axial center of the main body 4a, and a pipe 4c is disposed on the inner periphery of the axial hole 4a2. The The main body 4a is provided with a supply port 4a3 and a discharge port 4a4 that are open on the side surfaces, and are connected to a supply pipe 4d and a discharge pipe 4e, respectively (see FIG. 3). The cooling water supplied from the supply pipe 4d passes through the supply port 4a3 and the inside of the pipe 4c, and is supplied to the gap A between the tip of the shank 4a1 of the main body 4a and the fitting hole 4b1 of the chip 4b. In this gap A, the chip 4b is cooled by heat exchange between the cooling water and the chip 4b. Thereafter, the cooling water passes through the gap B between the axial hole 4a2 of the main body 4a and the pipe 4c, and is discharged to the discharge pipe 4e through the discharge port 4a4 provided in the main body 4a.

  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 member 3 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 member 3 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). ).

  A welding gun (not shown) has a first electrode 7a and a second electrode 7b (see FIG. 6). 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 substantially the same configuration as the contact member 4 shown in FIG. 3, and includes shaft-shaped main body portions 7a1 and 7b1 and tips 7a2 and 7b2 provided at the tips thereof.

  The spot welding apparatus 1 is provided with a control unit for controlling the operation of the clamping means 20, the raising and lowering of the contact member 4, the movement of the welding gun, the driving and energization of the first electrode 7a and the second electrode 7b (illustrated). (Omitted).

  Hereinafter, a procedure for performing welding on the workpiece W using the spot welding apparatus 1 will be described.

  First, as shown in FIG. 5, a clamp driving portion (not shown) provided in the clamping means 20 is driven, the tip of the clamp member 22 is retracted upward, and the clamper portion 21 is moved away from the placement portion 2a. In the state, the workpiece W is placed on the placement portion 2a of the workpiece set base 2 (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 metal plate W3 protruding downward, the hat portion H is disposed between the plurality of contact members 4. . In this state, the clamping means 20 of the workpiece set base 2 is closed (see arrow D), and the workpiece W is set to the workpiece set by clamping the flange portion F of the workpiece W from above and below with the clamper portion 21 and the placement portion 2a. Set on stand 2. In this embodiment, the clamp member 22 having a plurality of clamper members 21 (two in the illustrated example) is driven by one clamp drive portion (not shown), and the both sides of the hat portion H of the workpiece W are driven. The flange part F is clamped at once.

  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 abutting member 4 is brought into contact with a welded portion that has been welded in advance in the flange portion F of the workpiece W. At this time, since each contact member 4 is driven by the individual drive unit 5, each contact member 4 can be raised and brought into contact with the workpiece W reliably. Further, since it is possible to individually set the pressure for each contact member, for example, two contact members 4 that contact one flange portion F (left side in FIG. 2) and the other (FIG. 2). The pressure force can be varied with the single abutting member 4 that abuts on the right side flange portion. Of course, the applied pressure of all the contact members 4 may be equalized.

  By the way, if the abutting member 4 is fixed in advance to a position where it abuts on the workpiece W, the abutting member 4 can abut on the workpiece W at the same time as the workpiece W is set on the workpiece setting table 2. Seem. However, the position (height) of the tip of the contact member 4 varies depending on the fitting state of the shank portion 4a1 and the tip 4b and the wear amount of the tip 4b. There is a possibility that it may not come into contact with W or the applied pressure may be reduced. Therefore, if each abutting member 4 is individually driven and brought into contact with the workpiece W as described above, each abutting member is always irrespective of the fitting state of the shank 4a1 and the tip 4b and the wear amount of the tip 4b. 4 can be reliably brought into contact with the workpiece W with a predetermined pressure.

  Thereafter, the welding gun is moved by the robot arm, and as shown in FIG. 6, the hat portion H of the workpiece W and the conductive member 3 are disposed between the first electrode 7a and the second electrode 7b. 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 member 3 from below. In this state, by energizing between the electrodes 7a and 7b, an energization path of the first electrode 7a → work W → contact member 4 → connecting portion 6 → conductive member 3 → second electrode 7b is formed. The welding is applied to the planned welding portion P.

  At this time, the applied pressure by the electrodes 7a and 7b requires a relatively large applied pressure in order to close the gap between the metal plates W1 and W2 and ensure the welding quality. However, in this embodiment, since the conductive member 3 is fixed to the work set base 2, even if the pressure applied to the conductive member 3 by the second electrode 7b is increased, the pressure applied to the contact member 4 is not affected. Therefore, it is possible to avoid a situation in which the pressure applied to the contact member 4 is excessive and the workpiece W is deformed.

  Moreover, when the welding planned part P is provided in the part which covers the hat part H of the workpiece | work W as mentioned above, the welding scheduled part P cannot be clamped with both electrodes 7a and 7b, and the welding schedule of the workpiece | work W is carried out. It is necessary to pressurize only the first electrode 7a in contact with the portion P from above. At this time, since the planned welding portion P is not supported from below, the pressure applied to the first electrode 7a must be set to such an extent that the workpiece W is not deformed. Therefore, compared to the workpiece pressure (about 200 kg to 300 kg) in the normal direct spot welding in which the welding target portion P is sandwiched and pressed between the pair of electrodes, the pressure applied to the workpiece W by the first electrode 7a of the present embodiment is Get smaller. (For example, about 40 kg to 100 kg) Therefore, the gap between the metal plates W <b> 1 and W <b> 2 cannot be filled, and the workpiece W melts and scatters to cause spattering, which may deteriorate the welding quality.

  Therefore, in the present embodiment, the planned welding portion P is disposed in a position where the workpiece W is clamped by the placement portion 2a and the clamper portion 21, that is, in a region R surrounded by the clamped portion Wa. As a result, in the region R, a state in which the workpieces W are in close contact with each other is formed, so that the metal plates W1 and W2 are securely in close contact with each other in the planned welding portion P even if the pressure of the first electrode 7a is relatively small. Therefore, the occurrence of spatter can be suppressed and the welding quality can be improved.

  In the present embodiment, the inclined portion 3 b of the conductive member 3 is arranged in parallel to the surface including the planned welding portion P of the workpiece W. For this reason, as shown in FIG. 6, the electrodes 7a and 7b are brought into contact with each other from the direction perpendicular to the inclined portion 3b and the planned welding portion P of the workpiece W, so that the pressure applied by both the electrodes 7a and 7b Since it can transmit to W efficiently, welding quality can further be improved.

  On the other hand, the contact member 4 is in contact with a welded portion that has been previously welded among the flange portions F of the workpiece W, and functions as a ground electrode for energizing the workpiece W and the second electrode 7b. Therefore, the contact failure due to the insufficient pressure applied to the contact member 4 affects the function as the ground electrode, leading to deterioration of the quality of the welded portion. Therefore, the contact between the contact member 4 and the flange portion F of the workpiece W needs to be reliably performed. However, since the contact portion between the contact member 4 and the workpiece W, that is, the contacted portion Wb of the workpiece W is not supported from above, the workpiece W is formed when the contact member 4 has an excessive pressure. There is a risk of deformation. In the present embodiment, the contacted portion Wb is disposed in a region R surrounded by the clamped portion Wa. Thereby, contact failure can be prevented and a good weld can be obtained.

  When welding to one welding scheduled portion P is completed, both electrodes 7a and 7b are separated to release the pressure applied to the workpiece W and the conductive member 3. Then, the welding head is moved to the next welding scheduled portion P by the robot arm, and welding is performed in the same procedure as described above. At this time, since the workpiece W remains fixed at the clamped portion Wa, the position of the workpiece W does not change even if the first electrode 7a and the second electrode 7b are separated from each other, so that the workpiece W is accurately welded to a predetermined position. be able to. When the welding to all the planned welding portions P is completed, the driving member 5 lowers the contact member 4 to the retracted position, and the clamp means 20 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 above embodiment. For example, in the above-described embodiment, the case where the driving unit 5 is provided on each of the three abutting members 4 has been described. However, the present invention is not limited thereto, and at least two of them may be driven individually. For example, you may drive the two contact members 4 distribute | arranged along the flange part F of the one side with the same drive part 5. FIG. In this case, one drive unit 5 that drives the two contact members 4 disposed along the flange portion F on one side and one contact member disposed below the flange portion F on the other side. 4 and the other drive unit 5 that drives 4 is provided.

  In the above-described embodiment, the case where all the three driving units 5 are brought into contact with the workpiece W has been described. However, depending on the shape of the workpiece W, there may be a contact member 4 that does not need to be driven. . Therefore, you may make it a control part control the some drive part 5 so that only what is required among the some contact members 4 according to the kind of workpiece | work W may be driven. Thereby, since it can respond | correspond to the workpiece | work of various shapes, while the versatility of the spot welding apparatus 1 is improved, the energy which drives the unnecessary contact member 4 can be reduced. In addition, the contact member 4 that does not contact the workpiece W can be largely retracted from the workpiece W, and can be lowered, for example, below the conductive member 3. In this case, since a large gap is ensured between the contact member 4 and the workpiece W, access of the welding gun (particularly the second electrode 7b) is facilitated.

  Moreover, in said embodiment, although the thing provided with the two clamper parts 21 with respect to the one clamp member 22 is shown, it is not restricted to this, The clamper parts 21 according to the number of the mounting parts 2a. The number may be changed as appropriate. Further, the position at which the clamping means 20 is disposed may be appropriately changed as long as the workpiece W can be stably fixed and can be disposed so as to surround the welding scheduled portion P and the contacted portion Wb.

  Moreover, although the case where the three contact members 4 were provided was shown in said embodiment, it is not restricted to this, You may provide two or less contact members 4, or four or more.

  Moreover, although the case where the workpiece | work W which has the hat part H was welded was shown in said embodiment, if it is a workpiece | work which cannot contact | abut an electrode from the one side of the welding planned part P not only this, said spot Welding 1 can be suitably applied.

DESCRIPTION OF SYMBOLS 1 Spot welding apparatus 2 Work set base 20 Clamp means 21 Clamper part 22 Clamp member 3 Conductive member 3a Horizontal part 3b Inclined part 3c, 3d Insertion part 4 Contact member 5 Drive part 6 Connection part 7a 1st electrode 7b 2nd electrode W Workpiece Wa Clamped part Wb Contacted part H Hat part F Flange part P Welding part R Area

Claims (2)

A first electrode and a second electrode which are arranged on the same axis and are close to and away from each other; a conductive member which is arranged on one side of the workpiece; and a contact member which is connected to the conductive member so as to be energized; A drive unit that drives the contact member between a contact position that contacts the workpiece and a retracted position that does not contact the workpiece; and a clamp unit that clamps the workpiece; and clamps the workpiece by the clamp unit; The abutting member is brought into contact with the workpiece from one side, the second electrode is brought into contact with the conductive member, and the first electrode is brought into contact with the planned welding portion of the workpiece from the other side. A spot welding apparatus for welding the planned welding portion by energizing between the first electrode and the second electrode,
The spot welding apparatus characterized in that the planned welding portion is arranged in a region surrounded by a clamped portion clamped by the clamping means in the workpiece.   2. The spot welding apparatus according to claim 1, wherein the clamp means is provided with a clamper part capable of clamping a plurality of the clamped parts with one clamp driving part.

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