JP2000334574A - Auxiliary electrode device for spot welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily set a back electrode to a desired position corresponding to a work shape and to facilitate maintenance at a low cost by mounting plural electrodes held with a pair of welding tips together with members to be welded to respectively prescribed positions of deformable supporting members. SOLUTION: A bar like support member 15 is formed by bending a wire so as to go along the periphery of a work, holding members 14 are stuck to the bar like support member 15 at a prescribed interval corresponding to a welding pitch. A back electrode 11 is of a cylindrical shape and has a large diameter part in the axial direction end parts and a small diameter part in a center part in the axial direction. The small diameter part of the back electrode 11 is inserted to a C shaped holding member 14 to be an auxiliary electrode device for spot welding. The back electrode 11 is held by the holding member 14 with an appropriate end play. The work is placed on the back electrode 11, the work and the back electrode 11 are held together by welding tips, spot welding is performed by energizing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auxiliary electrode device for spot welding used for performing spot welding.

[0002]

2. Description of the Related Art When performing spot welding on a work to be welded, the work is sandwiched between a pair of welding tips of a welding gun with a predetermined pressing force, and in this state, electricity is supplied to perform welding. .

[0003] In the case of spot welding a work requiring a beautiful appearance, such as a panel material of an automobile body, for example, a relatively thick welded portion of the work is required to be beautifully and smoothly finished. After the back electrode made of a copper plate described above is brought into contact with the back electrode, the back electrode and the work are sandwiched by a pair of welding tips for welding.

FIG. 10 is a perspective view showing various conventional auxiliary electrode devices for spot welding.

The auxiliary electrode device 100 for spot welding shown in FIG. 10A has a back electrode 101 made of a band-like flat substantially rectangular plate, and is attached to support posts (not shown) via brackets 102 and 103. Have been. In FIG. 10A, only the screw fastening holes are shown in the back electrode 101 and the brackets 102 and 103, and the screw members are not shown (the same applies to the following drawings).

When performing spot welding at a plurality of points along the periphery of the work, first, the periphery of the work (not shown) is positioned on the back electrode 101 of the auxiliary electrode device 100 for spot welding to perform positioning. Then, the work is connected to the back electrode 1 by a pair of welding tips of a welding gun (not shown).
01 and welding is carried out in a state of being clamped together with 01. By doing so, the side of the workpiece that contacts the back electrode can be beautifully finished.

Further, when spot welding is performed at a plurality of points along the curved peripheral edge of a work such as a panel material, for example, a strip-like plate curved in the thickness direction as shown in FIG. A spot welding auxiliary electrode device 100a having a back electrode 101a is used. Further, when performing spot welding at a plurality of points along the meandering edge in the same plane of a work such as a panel material, for example, FIG.
An auxiliary electrode device for spot welding 100b having a back electrode 101b made of a band-shaped plate curved in the width direction as shown in FIG.

[0008]

By the way, in the above-mentioned conventional auxiliary electrode device for spot welding, the back electrode contacted along the periphery of the work such as the panel material is integrally formed by a band-shaped plate. Therefore, the following various problems have occurred.

That is, although spots to be spot-welded are spaced apart by a predetermined distance, a band-like plate is required to cover all of the spot-welded parts.

If the peripheral edge of a work such as a panel material is not straight, not only a large number of man-hours are required for the forming process for bending the strip-shaped plate, but also the peripheral shape of the work over the entire surface of the strip-shaped plate. There are difficulties that must be matched.

[0011] Further, the band-shaped plate is worn or deformed by repeated pressurization and energization by the welding tip during spot welding, thereby deteriorating the welding quality of a work such as a panel material. In order to prevent such deterioration in welding quality, the entire band-shaped plate serving as the back electrode must be replaced, and there is a problem that maintenance costs increase.

The present invention has been made in view of such problems of the prior art, and an object of the present invention is to make it possible to easily position a back electrode in accordance with the shape of a work, and to maintain the back electrode at low cost. Another object of the present invention is to provide an auxiliary electrode device for spot welding that is easy.

[0013]

The object of the present invention is achieved by the following means.

(1) A plurality of back electrodes which are in contact with a material to be welded and which are sandwiched by the pair of welding tips together with the material to be welded are respectively attached to predetermined positions of a deformable support member. Auxiliary electrode device for welding.

(2) A plurality of back electrodes that are in contact with the material to be welded and that are sandwiched by the pair of welding tips together with the material to be welded, a plurality of holding members that respectively hold the back electrodes, and the plurality of holding members. And a deformable rod-shaped support member each of which is fixed at a predetermined interval.

(3) The back electrode has a substantially cylindrical shape, and has a large-diameter portion formed at an axial end portion and a small-diameter portion formed at an axial central portion. The auxiliary electrode device for spot welding according to the above (2), further comprising a holding engagement hole into which the small diameter portion of the back electrode is inserted.

(4) The back electrode has a pair of parallel surface portions formed by cutting the small diameter portion with a pair of planes parallel to an axis, and the holding member is provided with one of the holding engagement holes. (3) for spot welding according to the above (3), wherein a cutout portion is formed, and a cutout portion having a width dimension larger than a mutual distance between the pair of parallel plane portions formed in the back electrode is provided. Auxiliary electrode device.

(5) The auxiliary electrode device for spot welding as described in (2) above, wherein a substantially spherical concave portion is formed on a surface of the back electrode that contacts the welding tip.

(6) The auxiliary electrode device for spot welding according to (2), wherein an insulating member for electrically separating the back electrode and the holding member is mounted between the back electrode and the holding member.

(7) The auxiliary electrode device for spot welding according to (2), wherein the rod-shaped support member has one end fixed and the other end movable in the axial direction.

(8) The rod-shaped support member has a square cross section perpendicular to the axis, and the holding member has a mounting engagement hole having a shape substantially matching the rectangular cross-sectional shape of the rod-shaped support member. The auxiliary electrode device for spot welding according to the above (2), further comprising a mounting portion through which the rod-shaped support member is inserted into the mounting engagement hole.

[0022]

According to the present invention, the following effects can be obtained for each claim.

According to the first or second aspect of the present invention, the plurality of back electrodes which are brought into contact with the material to be welded and held by the pair of welding tips together with the material to be welded are fixed to the predetermined supporting member which can be deformed. Since the support member is attached to the location, the support member can be easily formed and the back electrode can be positioned so as to follow the curved surface shape of the material to be welded such as a panel material. In addition, at the time of welding, even if the back electrode is slightly separated from the surface of the material to be welded, the support member can flexibly deform and follow the curved shape of the material to be welded, and unnecessary force is applied to the material to be welded itself. Good welding becomes possible without applying heat.

Further, since the back electrode only needs to be provided at a necessary position corresponding to the welding pitch, it is not necessary to secure dimensional accuracy over the entire length of the apparatus, and the material of the back electrode and the like can be used efficiently. Eliminate waste. In addition, the back electrode can be used in common even in the auxiliary electrode device for spot welding for different materials to be welded, and the versatility is high.

Further, even if the back electrode is worn or deformed due to the repetition of pressurization and energization by the welding tip, the back electrode can be easily replaced or the end face of the back electrode can be easily corrected. The maintainability is greatly improved.

According to the third aspect of the present invention, in addition to the effect of the second aspect of the present invention, the small diameter portion of the back electrode is firmly engaged with the holding engagement hole of the holding member. At the same time, the large diameter portion prevents falling off, so that it is securely held.

According to the fourth aspect of the present invention, in addition to the effect of the third aspect of the present invention, the back electrode is inserted through the notch into the inside of the holding member, and the back electrode is inserted into the holding engagement hole. About 9
By rotating by 0 °, it is possible to prevent the back electrode from coming off in the direction of the notch and coming off.

According to the fifth aspect of the invention, in addition to the effect of the second aspect of the present invention, the tip of the welding tip enters the recess of the back electrode during welding.
The situation where the tip of the welding tip slips on the surface of the back electrode is prevented, and the welding quality is improved and stabilized.

According to the sixth aspect of the present invention, in addition to the effect of the second aspect of the present invention, when current is supplied between the welding tips, it is ensured that a current leaks to the holding member or the rod-shaped support member. This can be prevented.

According to the seventh aspect of the invention, in addition to the effect of the second aspect of the invention, the degree of freedom of deformation of the rod-shaped support member is increased, and as a result, the length of the rod-shaped support member can be changed in the length direction by changing the welding pitch. When a change occurs, a local bending deformation portion is formed on the rod-shaped support member, and when it is necessary to further correct the inclination angle of the welding point, a local torsional deformation portion is formed on the rod-shaped support member. By forming, it is possible to cope with it.

According to the eighth aspect of the present invention, in addition to the effect of the second aspect of the present invention, while the holding member is easily moved along the axial direction of the rod-shaped support member, the holding member is Rotation around the axis of the member can be restricted. As a result, the position of the back electrode can be appropriately adjusted, and it is possible to flexibly cope with a delicate correction or a change in the welding pitch.

[0032]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view showing a schematic configuration of an auxiliary electrode device for spot welding according to one embodiment of the present invention, and FIG.
Is an enlarged perspective view showing a main part of FIG. 1, FIG. 3 is a perspective view showing a back electrode, FIG. 4 is a plan view showing a state of installing the back electrode, and FIG. 5 is a state of spot welding a work. FIG.

As shown in FIGS. 1 and 2, the spot welding auxiliary electrode device 10 is brought into contact with a workpiece W which is a material to be welded, and is formed by a pair of welding tips T1 and T2 (see FIG. 5). Back electrodes 11 sandwiched together
And a plurality of holding members 14 for holding the back electrodes 11 respectively, and a deformable rod-shaped support member 15 to which the plurality of holding members are fixed at predetermined intervals. The rod-shaped support member 15 is mounted on the base 1.
6 and support brackets 17 and 18
Attached via 2,13.

As shown in FIG. 3, the back electrode 11 has a cylindrical shape, and has large diameter portions 19 and 20 formed at both ends in the axial direction and small diameter portions 21 formed at the central portion in the axial direction. are doing. Therefore, the back electrode 11 is formed such that an annular concave groove is formed in the central portion in the axial direction along the circumferential direction. In addition, the back electrode 11 has a pair of parallel plane portions 22 and 23 formed by equally removing the opposite sides of the small diameter portion 21 with a pair of planes parallel to the axis.

Since the back electrode 11 functions as a relay electrode, it is formed of a material having a low electric resistance, for example, copper or a copper alloy.

As shown in FIG. 4, the holding member 14 has a C-shape. The holding member 14 can be made by bending an iron or steel wire, for example, and a wire having a diameter of, for example, 2 to 4 mm is used. Holding member 1
4 has a holding engagement hole 24 at the center thereof into which the small diameter portion 21 of the back electrode 11 is inserted. The diameter D2 of the holding engagement hole 24 is slightly larger than the diameter D1 of the small diameter portion 21 of the back electrode 11 and smaller than the diameter D3 of the large diameter portions 19 and 20. Therefore, the back electrode 11 has the small diameter portion 21 firmly engaged with the holding engagement hole 24 of the holding member 14 and the large diameter portions 19 and 2.
By being prevented from falling off by 0, it is securely held.

The axial dimension of the holding member 14, that is, the diameter d of the wire is slightly smaller than the axial length L1 of the small-diameter portion 21 of the back electrode 11, and the gap G in FIG. It is set to be 0.5 to 2 mm.
Therefore, the back electrode 11 is
It is held with moderate play in the axial direction. Thereby, not only the upper surface of the back electrode 11 and the lower surface of the work W but also the plurality of back electrodes 11 can absorb variations in the positional relationship in the vertical direction.

Further, the holding member 14 is provided with the holding engagement hole 2.
4 has a cutout portion 25 formed by cutting out a part thereof. The width L2 of the notch 25 of the holding member 14 is
The distance between the pair of parallel plane portions 22 and 23 formed on the small diameter portion 21 of the back electrode 11 is set to be larger than the mutual distance L3. Therefore, when the back electrode 11 is installed on the holding member 14, as shown in FIG.
1 is inserted into the holding member 14 through the notch 25 in the direction indicated by the white arrow in the figure with the pair of parallel plane portions 22 and 23 facing in the left-right direction. Then, as shown in FIG. 4B, the back electrode 11 is
By rotating by 0 °, the back electrode 11
5 is prevented from coming off in the direction of 5.

The bar-shaped support member 15 can be easily formed by bending a wire of iron or steel, for example, along the periphery of a work such as a panel material. For example, a wire having a diameter of 4 to 5 mm is used. This rod-shaped support member 1
5, the holding members 14 are fixed at predetermined intervals so as to correspond to the welding pitch P, for example, by welding or the like. In the drawing, the case of equal pitch is shown.

The rod-shaped support member 15 has one end fixed and the other end movable in the axial direction. Specifically, one end of the rod-shaped support member 15 is fixed to the bracket 13 by welding or the like, and the other end is slidably inserted into a support hole 27 of a cylindrical portion 26 provided on the bracket 12. . With this configuration, the degree of freedom of deformation of the rod-shaped support member 15 is increased, and as a result, even when a change occurs in the length direction due to a change in welding pitch or the like, the local bending deformation portion 28 is formed on the rod-shaped support member 15. This can be dealt with by forming, and even when the inclination angle of the welding point needs to be corrected, the local torsional deformation portion 2
9 can be dealt with. In addition,
Mounting holes 31 and 32 are formed in the brackets 12 and 13, and screw members (not shown) are inserted into the mounting holes 31 and 32 and the brackets 12 and 13 are supported by the support posts 17 and 18.
To be concluded.

When the works W1 and W2 are spot-welded using the spot welding auxiliary electrode device 10 configured as described above, first, as shown in FIG.
, W2 are positioned such that their peripheral edges are located above the back electrode 11. At this time, the side on which the welded portion of the work needs to be beautifully and smoothly finished faces the back electrode 11. FIG. 5 shows a cross section taken along a plane perpendicular to the axis of the rod-shaped support member 15.

Then, a pair of welding tips T1 of the welding gun
, T2 are moved to hold the workpieces W1, W2 together with the back electrode 11, and in this state, electricity is supplied to perform spot welding. At this time, since the flat upper surface of the back electrode 11 contacts the lower surface of the work in a wide range, the pressure applied to the work by the welding tip T2 is dispersed, and the side of the work with which the back electrode is in contact is beautifully finished.

Next, since the back electrode 11 is fixed to the rod-shaped support member 15 at other positions to be welded according to the welding pitch, the welding tips T1, T2 are sequentially moved toward the respective back electrodes 11. , A series of spot welding is performed.

As described above, according to the present embodiment, the work W
The plurality of back electrodes 11 which are brought into contact with the workpiece W and held by the pair of welding tips T1 and T2 together with the workpiece W are attached to predetermined positions of the deformable rod-shaped support member 15, respectively. The rod-shaped support member 15 can be easily formed to position the back electrode 11 so as to follow the curved surface shape of the work W. Moreover, at the time of welding,
Even if the back electrode 11 is slightly separated from the surface of the work W such as a panel material, the rod-shaped support member 1 is formed in the curved shape of the work W.
5 can flexibly deform and follow, and good welding can be performed without applying unnecessary force to the work W.

Further, since the back electrode 11 only needs to be installed at a necessary position corresponding to the welding pitch, it is not necessary to secure dimensional accuracy over the entire length of the apparatus, and the material of the back electrode 11 and the like are used efficiently. And no waste. In addition, the back electrode can be used in common even in an auxiliary electrode device for spot welding for different works, and the versatility is high.

Further, even if the back electrode 11 is worn or deformed due to repetition of pressurization and energization by the welding tips T1 and T2, only the back electrode 11 is replaced or the end surface of the back electrode 11 is shaved. Modifications can be made easily, and maintainability is greatly improved.

FIG. 6 is a plan view showing a holding member of an auxiliary electrode device for spot welding according to another embodiment, and FIG. 7 is a longitudinal sectional view showing how a workpiece is spot-welded.

In this embodiment, an insulating member 33 is provided between the small diameter portion 21 of the back electrode 11 and the engaging hole of the holding member 14a to electrically separate them from each other. Further, the holding member 14a has a rectangular plate shape in which a holding engagement hole 24a into which the small-diameter portion 21 of the back electrode 11 is inserted is formed in the center. However, the other points are the same as those of the above-described apparatus of FIG. 1, and thus the description thereof is omitted, and the same members are denoted by the same reference numerals. FIG. 6 shows a cross section cut along a vertical plane parallel to the axis of the rod-shaped support member 15.

When a current is applied between the welding tips T1 and T2,
Normally, most of the current flows through the back electrode 11 having a low electric resistance. However, according to this embodiment, even if the welding conditions are such that there is a risk of shunting to the holding member or the rod-shaped support member. Thus, it is possible to reliably prevent current leakage.

FIG. 8 is a schematic longitudinal sectional view of an auxiliary electrode device for spot welding according to still another embodiment.

In this embodiment, the rod-shaped support member 15a has a square cross section perpendicular to the axis, and for example, a drawn square rod is used. Further, the holding member 14b includes a rod-shaped support member 15a.
A mounting engagement hole 35 having a shape substantially coinciding with the rectangular cross-sectional shape is formed, and a mounting portion 36 through which the rod-shaped support member 15a is inserted into the support engagement hole 35, and is integrally formed with the mounting portion 36. And a holding portion 37 having a rectangular plate shape in which a holding engagement hole 24b into which the small-diameter portion 21 of the back electrode 11 is inserted is formed at the center. Further, a screw member 38 for fixing the mounting portion 36 of the holding member 14b to a predetermined position of the rod-shaped support member 15a is provided. However, the other points are the same as those of the above-described apparatus of FIG. 1, and thus the description thereof is omitted, and the same members are denoted by the same reference numerals. FIG. 8 shows a cross section taken along a plane perpendicular to the axis of the rod-shaped support member 15a.

According to this embodiment, it is possible to restrict the rotation of the holding member 14b around the axis of the rod-shaped support member 15a while easily moving the holding member 14b along the axial direction of the rod-shaped support member 15a. it can. As a result, the position of the back electrode 11 can be appropriately adjusted,
It can flexibly respond to subtle corrections and changes in welding pitch. The cross-sectional square shape of the rod-shaped support member 15a is as follows.
The shape is not limited to the illustrated quadrangle, but may be an appropriate polygon such as a hexagon.

FIG. 9 is a schematic longitudinal sectional view of an auxiliary electrode device for spot welding according to still another embodiment.

In this embodiment, the mounting portion 36a of the holding member 14c has a U-shaped section 41 in which a groove 42 is formed and a lid 43. The rod-shaped support member 15a is
After being inserted into the inside, the holding member 14c can be fixed at a desired position in the axial direction of the rod-shaped support member 15a by applying the cover 43 and tightening with the screw member 44. A substantially spherical concave portion 45 is formed on the surface of the back electrode 11 that contacts the welding tip. However, the other points are the same as those in the above-described apparatus in FIG. 8, and thus the description thereof is omitted, and the same members are denoted by the same reference numerals.

According to this embodiment, the rod-shaped support member 15
Even if a is curved or twisted, it becomes easier to move and adjust the position of the back electrode 11. In addition, since the tip of the welding tip enters the recess 45 of the back electrode 11 during welding, the situation where the tip of the welding tip slips on the surface of the back electrode 11 is prevented, and the welding quality is improved and stabilized.

The embodiments described above are not described to limit the present invention, and various modifications can be made by those skilled in the art within the technical concept of the present invention.

For example, in the above embodiment, a rod-shaped support member such as a round bar or a square bar is used. However, the present invention is not limited to this. It may be one that partially uses a rod-shaped support member. Further, the back electrode is not limited to the one having a substantially columnar shape, and may be, for example, a prismatic shape. Furthermore, the method of attaching the back electrode to the rod-shaped support member is arbitrary.

[Brief description of the drawings]

FIG. 1 is a front view showing a schematic configuration of an auxiliary electrode device for spot welding according to an embodiment of the present invention.

FIG. 2 is an enlarged perspective view showing a main part of FIG.

FIG. 3 is a perspective view showing a back electrode.

FIG. 4 is a plan view showing how a back electrode is installed.

FIG. 5 is a longitudinal sectional view showing a state where a work is spot-welded.

FIG. 6 is a plan view showing a holding member of an auxiliary electrode device for spot welding according to another embodiment.

FIG. 7 is a longitudinal sectional view showing a state where a work is spot-welded.

FIG. 8 is a schematic longitudinal sectional view of an auxiliary electrode device for spot welding according to still another embodiment.

FIG. 9 is a schematic longitudinal sectional view of an auxiliary electrode device for spot welding according to still another embodiment.

FIG. 10 is a perspective view showing various conventional auxiliary electrode devices for spot welding.

[Explanation of symbols]

 Reference Signs List 10: spot welding auxiliary electrode device, 11: back electrode, 14: holding member, 15, 15a: rod-shaped support member (support member), 19, 20: large diameter portion, 21: small diameter portion, 22, 23: parallel surface portion .., 24, 24a, 24b ... retaining engagement holes, 25 ... notches, 33 ... insulating members, 36 ... mounting parts, 45 ... recesses, T1, T2 ... welding tips, W, W1, W2 ... workpieces (weld to be welded) ).

Claims (8)

[Claims] 1. A spot welding method, wherein a plurality of back electrodes abutting on a material to be welded and sandwiched between the pair of welding tips and the material to be welded are respectively attached to predetermined positions of a deformable support member. Auxiliary electrode device. 2. A plurality of back electrodes which are in contact with the material to be welded and are sandwiched by the pair of welding tips together with the material to be welded, a plurality of holding members respectively holding the back electrodes, and the plurality of holding members. An auxiliary electrode device for spot welding, comprising: a deformable rod-shaped support member fixed at a predetermined interval. 3. The back electrode has a substantially cylindrical shape, and has a large diameter portion formed at an axial end portion and a small diameter portion formed at an axial center portion. The auxiliary electrode device for spot welding according to claim 2, further comprising a holding engagement hole into which the small diameter portion of the back electrode is inserted. 4. The back electrode has a pair of parallel surface portions formed by cutting the small diameter portion along a pair of planes parallel to an axis, and the holding member is a part of the holding engagement hole. 4. The auxiliary electrode device for spot welding according to claim 3, wherein the auxiliary electrode device has a notch portion formed by notching and having a width dimension larger than a mutual distance between the pair of parallel surface portions formed on the back electrode. . 5. The auxiliary electrode device for spot welding according to claim 2, wherein a substantially spherical concave portion is formed on a surface of the back electrode that comes into contact with the welding tip. 6. The auxiliary electrode device for spot welding according to claim 2, wherein an insulating member for electrically separating the back electrode and the holding member is mounted between the back electrode and the holding member. 7. The rod-shaped support member has one end fixed,
The auxiliary electrode device for spot welding according to claim 2, wherein the other end is movable in the axial direction. 8. The rod-shaped support member has a rectangular cross section perpendicular to the axis, and the holding member has a mounting engagement hole having a shape substantially matching the rectangular cross-sectional shape of the rod-shaped support member. The auxiliary electrode device for spot welding according to claim 2, further comprising a mounting portion through which the rod-shaped support member is inserted into the engagement hole.