JP2014069213A - Spot welding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spot welding apparatus which electrifies a pair of contact members and a workpiece and brings a plurality of contact members reliably into contact with a workpiece independent of the shape of the workpiece.SOLUTION: A spot welding apparatus welds a part P to be welded by bringing contact members 4 into contact with a workpiece W from under the workpiece W, bringing a second electrode 7b into contact with a conductive member 3, then bringing a first electrode 7a into contact with the to-be-welded part P from over the to-be-welded part P and electrifying across the first electrode 7a and the second electrode 7b in the contact status. At least two contact members 4 are provided, and a drive part 5 is arranged in each of the contact members 4.

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. A general spot welding method is performed using a welding gun provided with a C-shaped gun yoke having a pair of electrodes arranged opposite to each other. Specifically, after moving the welding gun attached to the robot arm or the like to a position where the workpiece is disposed between the pair of electrodes, the workpiece is sandwiched between the pair of electrodes and pressurized with a predetermined pressure. However, welding is performed by energizing between the pair of electrodes.

  However, for example, as shown in FIG. 1, when one side of the planned welding portion P is covered with a metal plate W3 having a cross-sectional hat shape, the top surface of the planned welding portion P and the hat portion H (a lower surface in the figure) with a pair of electrodes. ) To be pressed and welded. Thus, if the top surface of the hat portion H is directly pressurized with an electrode, the hat portion may be deformed.

  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 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. Then, in a state where the pair of contact members are in contact with the workpiece from one side at a position avoiding the hat portion, one electrode is brought into contact with the workpiece from the other side, and the other electrode is brought into contact with the conductive member. The contact is made from the side, and welding is performed by energizing between the pair of electrodes in this state. According to this spot welding apparatus, since the hat portion is not directly pressurized with the pair of electrodes, deformation of the hat portion can be avoided.

JP 2008-246554 A

  In the spot welding apparatus of the above-mentioned patent document 1, in order to energize the pair of abutting members and the workpiece W, it is necessary to surely abut each abutting member on the workpiece W. Therefore, in the above spot welding apparatus, the conduction means (conductive member and contact member) is connected to the support member so as to be swingable, and the support member is connected to the robot arm via the cylinder. Then, the conduction means is arranged on one side of the workpiece by the robot arm, and in this state, the conduction means is pushed into the workpiece side by the cylinder to bring the contact member into contact with the workpiece. At this time, the conductive member swings in accordance with the shape of the workpiece, so that the tips of the pair of abutting members are reliably brought into contact with the workpiece.

  However, if one of the contact members is brought into contact with the work and then the conductive member is swung, it is necessary to slide the one contact member with respect to the work. Actually, it is very difficult to swing the conductive member by this sliding resistance, and it cannot be said that the pair of contact members can be reliably brought into contact with the workpiece in the above configuration.

  An object of the present invention is to reliably bring a plurality of abutting members into contact with a workpiece regardless of the shape of the workpiece.

  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, and a conductive member arranged on one side of the workpiece, An abutting member connected to the conductive member so as to be energized; and a drive unit that drives the abutting member between a contact position that contacts the workpiece and a retracted position that does not contact the workpiece; The 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 the planned welding portion by energizing between one electrode and the second electrode, wherein at least two contact members are provided, and each of the two contact members is driven by the drive. A feature is provided.

  Thus, in the spot welding apparatus of the present invention, the two abutting members are each driven by separate drive units. As a result, each drive unit can drive the contact member to a position where it comes into contact with the workpiece, so that each contact member can be reliably contacted with the workpiece regardless of the shape of the workpiece.

  For example, in order to avoid interference between the contact member and the conductive member, if the contact member is arranged side by side on the side of the conductive member, a space for arranging both members increases. Therefore, when the conductive member is provided with an insertion portion that penetrates in the moving direction of the contact member, and the contact member is inserted through the inner periphery of the insertion portion, the contact member is arranged side by side on the conductive member. In comparison, the arrangement space for both members is reduced, and the spot welding apparatus can be miniaturized.

  In the above spot welding device, it is possible to handle workpieces of various shapes by providing a control unit that controls the drive unit so as to drive only the necessary one of the contact members according to the type of workpiece. Thus, versatility is improved and energy for driving unnecessary contact members can be reduced.

  As described above, according to the spot welding apparatus of the present invention, a plurality of contact members can be reliably brought into contact with the workpiece regardless of the shape of the workpiece.

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), Is 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 placement part 2a and the pressing part 2d are provided at positions where a plurality of positions of the workpiece W are pressed, and are provided at positions surrounding the planned welding part P in this embodiment. Specifically, as shown in FIG. 2, the placement portion 2 a and the pressing portion 2 d are provided at three or more locations (4 locations in the illustrated example), and at least one (3 in the illustrated example) is surrounded by these. Are to be welded (see FIG. 2).

  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 set on the workpiece setting table 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 made 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 as an insertion portion in the conductive member 3 and the contact member 4 is inserted in 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 FIG. 1, 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. Is increased. 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 controller that controls the rotation of the clamp member 2b, 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 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 metal plate W3 projecting 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.

  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 a separate 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 pressing force for each contact member 4, 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 flange portion F on the right side of 2. Of course, the pressing force 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. Seems also. However, the position (height) of the tip of the contact member 4 varies depending on the fitting state of the shank 4a1 and the tip 4b and the wear amount of the tip 4b. There is a risk that it will not come into contact with the surface, and the applied pressure may be reduced. Therefore, if each contact member 4 is individually driven and brought into contact with the workpiece W as described above, each contact is always made regardless of the fitting state of the shank 4a1 and the tip 4b and the wear amount of the tip 4b. The member 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, the work W and the conductive member 3 are sandwiched and pressed by the electrodes 7a and 7b and energized between the electrodes 7a and 7b, whereby the first electrode 7a → work W → contact member 4 → connecting portion. An energization path of 6 → conductive member 3 → second electrode 7b is formed, and welding is applied to the planned welding portion P of the workpiece W.

  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. In the present embodiment, since the conductive member 3 is fixed to the work set base 2, the pressure applied by the second electrode 7 b to the conductive member 3 is not transmitted to the pressure applied to the workpiece W by the contact member 4. Therefore, even when the applied pressure of both electrodes 7a and 7b is increased, the applied pressure of the contact member 4 is not affected, and the situation where the applied pressure of the contact member 4 becomes excessive and the workpiece W is deformed can be avoided. .

  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 planned part P cannot be clamped by 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 welding scheduled portion P is not supported from below, the pressing force of the first electrode 7a must be set to such an extent that the workpiece W is not deformed. Therefore, compared with the pressure applied to the workpiece (about 200 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. Becomes smaller (for example, about 40 to 100 kg). For this reason, the clearance gap between the metal plates W1 and W2 cannot be closed, and there exists a possibility that welding quality may deteriorate. Therefore, in the present embodiment, the mounting portion 2a and the pressing portion 2d are provided so as to surround the periphery of the planned welding portion P. Thereby, since the area | region clamped by the mounting part 2a and the holding | suppressing part 2d among the workpiece | work W can make the clearance gap between the metal plates W1 and W2 substantially 0, the applied pressure of the 1st electrode 7a is comparatively comparative. Even if it is small, the metal plates W1 and W2 can be reliably brought into contact with each other in the planned welding portion P, so that 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, whereby the pressure applied by the electrodes 7a and 7b is applied to the workpiece. Since it can transmit to W efficiently, welding quality can further be improved.

  On the other hand, the abutting member 4 abuts on a welded portion that has been welded in advance in the flange portion F of the workpiece W, and functions as a ground electrode for energizing the workpiece W and the second electrode 7b. is there. Therefore, it is not necessary to close the gap between the metal plates in the flange portion F by pressurizing the contact member 4, so that the pressure applied to the workpiece W by the contact member 4 does not have to be so large. Further, since the contact portion between the contact member 4 and the workpiece W is not supported from above, the workpiece W may be deformed if the applied pressure of the contact member 4 is too large. Accordingly, the pressure applied to the contact member 4 is, for example, about 1/10 to 1/2 of the pressure applied by the first electrode 7a and the second electrode 7b, specifically about 10 to 20 kg.

  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 scheduled welding portion by the robot arm, and welding is performed in the same procedure as described above. 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 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 separately. 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 the workpiece | work W of various shapes can be responded, the versatility of the spot welding apparatus 1 is improved and the energy which drives the unnecessary contact member 4 can be reduced. Further, the abutting member 4 that is not abutted against 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, 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 contact members 4 or four or more.

  In the above embodiment, the case where the workpiece W having the hat portion H is welded is shown. However, the present invention is not limited to this, and if the workpiece cannot contact the electrode from one side of the planned welding portion P, Said spot welding apparatus 1 can be applied suitably.

DESCRIPTION OF SYMBOLS 1 Spot welding apparatus 2 Work set base 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 Work H Hat part F Flange part P Welding Planned part

Claims (3)

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, the contact member contacting the workpiece from one side; Two electrodes are brought into contact with the conductive member, and further, the first electrode is brought into contact with the planned welding portion of the workpiece from the other side, and in this state, current is passed between the first electrode and the second electrode. A spot welding device for welding the planned welding portion,
A spot welding apparatus in which at least two abutting members are provided, and the driving portion is provided on each of the two abutting members.   The spot welding apparatus according to claim 1, wherein the conductive member is provided with an insertion portion penetrating in the moving direction of the contact member, and the contact member is inserted through an inner periphery of the insertion portion.   3. The spot welding apparatus according to claim 1, further comprising a control unit that controls the drive unit so as to drive only the necessary members of the contact members according to the type of workpiece.

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