Projection welding member

Abstract

To provide a projection welding member which can perform projection welding even on two thick steel plates to be welded at a low cost.SOLUTION: A projection welding member includes: a first joining section 11 which has an area having substantially the same size as a contact surface when a first steel plate 100 is made to abut on a second steel plate 110; a second joining section 12 which has an area of a size which comes into contact with one of two side faces 100a, 100b in a thickness direction of the first steel plate 100 when the first steel plate 100 is made to abut on the second steel plate 110; a third joining section 13 which has an area of a size which comes into contact with the other of the two side faces 100a, 100b in the thickness direction of the first steel plate 100; a first projection section 14 which comes into point contact with each of the first steel plate 100 and the second steel plate 110 in the vicinity of the second joining section 12 in the first joining section 11; and a second projection section 15 which comes into point contact with each of the first steel plate 100 and the second steel plate 110 in the vicinity of the third joining section 13 in the first joining section 11.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a projection welding member suitable for use in a resistance welding apparatus that sandwiches a plate assembly (weldment) formed by overlapping two steel plates between two electrodes, energizes while applying pressure, and performs welding.

Background Art

[0002] Among resistance welding apparatuses, there is one called a table type in which one of the two electrodes (lower side) is fixed in a table shape and the other (upper side) is arranged in a gun shape so as to be movable up, down, left, and right. In this type of resistance welding apparatus, the weldment is sandwiched between a table-type electrode and a gun-type electrode, and welding is performed by energizing while applying pressure with the gun-type electrode.

[0003] By the way, in resistance welding, in order to obtain good welding, a protrusion called a projection is formed on one of the two steel plates (see, for example, Patent Document 1). Here, an example of a projection is shown in FIGS. 7 and 8. In FIG. 7, (a) is a side view of the steel plate 200, and (b) is a view of the steel plate 200 as seen from the direction of arrow J. On the steel plate 200, mountain-shaped projections 201 and 202 are formed at intervals in the longitudinal direction (arrow K direction) of the steel plate 200.

[0004] FIG. 9 is a view showing a state when the steel plate 200 and the steel plate 210 are joined. As shown in the figure, when welding the steel plate 200 and the steel plate 210, the tips of the projections 201 and 202 formed on the steel plate 200 come into contact with each other at one point. In this state, by supplying current between the steel plates and applying pressure, current flows concentratedly at the locations where the projections are formed. As a result, the projections 201 and 202 melt, and further melt over the entire contact surface between the steel plate 200 and the steel plate 210, and the steel plate 200 and the steel plate 210 are joined.

[0005] In FIG. 8, (a) is a side view of the steel plate 220, and (b) is a view of the steel plate 220 as seen from the direction of arrow M. In the steel plate 220, projections 221 and 222 each having a V-shaped cross section are formed at intervals in the longitudinal direction of the steel plate 220 (the direction of arrow N). When the steel plate 220 is welded to the other steel plate 210 (see FIG. 9), the tips of the projections 221 and 222 come into contact with each other at two locations. In this state, a current is supplied between the steel plates and pressure is applied, so that the current flows concentratedly at the locations where the projections are formed. As a result, the projections 221 and 222 melt, and further melt over the entire contact surface between the steel plate 220 and the steel plate 210, and the steel plate 220 and the steel plate 210 are joined together.

[0006] Note that in the above example, the projection was provided only on one of the steel plates of the plate assembly, but there are also cases where the projection is provided on the other steel plate of the plate assembly (see, for example, Patent Document 2).

[0007] In addition, there are cases where a projection is provided on a nut (see Patent Documents 3 and 4), and there are also cases where a projection is provided on a washer (see Patent Document 5).

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0009] Incidentally, when forming a projection on a steel plate, as the thickness of the steel plate increases, it is necessary to increase the thickness of the projection accordingly, and there is a problem that the labor required for projection processing increases. Incidentally, in recent years, the opportunities for multi-variety and small-batch production have been increasing. When projection processing is performed according to the thickness of the steel plate, the increase in the labor required for projection processing is directly reflected in the cost. The thickness of the steel plate 200 shown in FIG. 7 is "L1" as shown in (b) of the same figure. Also, the thickness of the steel plate 220 shown in FIG. 8 is "L2" as shown in (b) of the same figure.

[0010] The present invention has been made in view of such circumstances, and an object thereof is to provide a projection welding member that can perform projection welding at low cost even when two steel plates to be welded are thick.

Means for Solving the Problems

[0011] The projection welding member of the present invention is used when joining a first steel plate and a second steel plate by resistance welding, and has a first joint portion having an area approximately the same size as the contact surface when the first steel plate is applied to the second steel plate, a second joint portion having an area sized to contact one of two side surfaces in the thickness direction of the first steel plate when the first steel plate is applied to the second steel plate, a third joint portion having an area sized to contact the other of the two side surfaces in the thickness direction of the first steel plate when the first steel plate is applied to the second steel plate, a first protrusion provided near the second joint portion of the first joint portion and contacting at least one location on each of the first steel plate and the second steel plate, and a second protrusion provided near the third joint portion of the first joint portion and contacting at least one location on each of the first steel plate and the second steel plate. The first joint portion, the second joint portion, the third joint portion, the first protrusion, and the second protrusion are integrally formed.

[0012] According to the above configuration, by arranging the first joint portion so as to enter between the first and second steel plates in the width direction of the first steel plate, the second joint portion contacts one side surface of the first steel plate, and the third joint portion contacts the other side surface of the first steel plate. Further, the first protrusion contacts at least one location on each of the first steel plate and the second steel plate near the second joint portion of the first joint portion, and the second protrusion contacts at least one location on each of the first steel plate and the second steel plate near the third joint portion of the first joint portion.

[0013] When welding the first steel plate and the second steel plate, the projection welding member having the above configuration is arranged between these steel plates, and then the first steel plate is pressed toward the second steel plate, and a current is passed between them. Since the current flowing from the first steel plate to the second steel plate concentrates on the first protrusion and the second protrusion acting as projections, the projection welding member melts, and further melts over the entire contact surface between the first steel plate and the second steel plate, and the first steel plate and the second steel plate are joined.

[0014] Thus, the projection welding member of the present invention has a structure that is attached to the first steel plate and acts as a projection for joining the first steel plate and the second steel plate. Therefore, even if the steel plate to be welded is thick, by making the shape according to the thickness, compared with obtaining a projection by processing the steel plate itself as in the prior art, the projection processing is not required, and the cost can be reduced. That is, it becomes possible to perform welding by projection at low cost.

Brief Description of the Drawings

[0015]

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Figure 10

Mode for Carrying Out the Invention

[0016] Before explaining one embodiment of the projection welding member of the present invention, an example of a resistance welding apparatus used for resistance welding will be described.

[0017] FIG. 10 is a side view showing the appearance of a resistance welding apparatus 500 developed by the inventors. In the figure, the resistance welding apparatus 500 includes a welding gun in a vertical posture (hereinafter referred to as "vertical gun") 502, a table electrode 503, a column 513, a support arm 514, a pedestal 515, a welding transformer 516, a power supply cable 517, and a control device 518.

[0018] The vertical gun 502 includes a shank holder 505, a crankshaft 506, a gun shaft 507, a gun holder 508, a handle 509, a pressurizing device 510, and a power supply device 511. An electrode 540 is attached to the shank holder 505 via a shank 530. The shank holder 505, the crankshaft 506, and the gun shaft 507 are each formed of a cylindrical rod made of a metal material (mainly copper) having conductivity. The gun shaft 507 is inserted into the gun holder 508. The gun holder 508 is supported by the support arm 514.

[0019] The vertical gun 502 is vertically movable in a direction perpendicular to the plane direction of the table electrode 503 and is supported so as to be movable in the plane direction of the table electrode 503. Further, the vertical gun 502 is held in a state of being pulled up with a constant tension by a lifting mechanism 520 disposed at the tip portion of the support arm 514. By the action of the lifting mechanism 520, the vertical gun 502 can be held at an arbitrary position in the vertical direction. Further, the vertical gun 502 can rotate about the axis of the gun holder 508.

[0020] The gun holder 508 has a cylindrical rod shape and is disposed on the lower surface of the tip portion of the support arm 514 in a direction perpendicular to the arm direction of the support arm 514. A gun shaft 507 is inserted into the gun holder 508. The handle 509 is used for operating the vertical gun 502. That is, by operating the handle 509, the vertical gun 502 can be rotated or moved vertically. A push-button type start switch (not shown) is disposed on the handle 509, and by operating this start switch, a welding command is output to the control device 518.

[0021] The pressurizing device 510 is disposed on the upper surface of the tip portion of the support arm 514. The pressurizing device 510 pressurizes the gun shaft 507 downward (the direction where the table electrode 503 is located), and by receiving the supply of compressed air during welding, the gun shaft 507 is gripped and pushed downward (toward the table electrode 503 side).

[0022] The power supply device 511 supplies power from the welding transformer 516 to the vertical gun 502. The power supply device 511 incorporates two contacts (not shown), and these contacts become a contact state (on state) or a non-contact state (off state) by the injection and discharge of air from the outside. The power supply device 511 is turned on under the control of the control device 518 during welding. When the power supply device 511 is turned on, power from the welding transformer 516 is supplied to the vertical gun 502.

[0023] The table electrode 503 is formed in a substantially square flat plate shape from a conductive metal material (mainly copper). The table electrode 503 is disposed below the vertical gun 502 in a direction perpendicular to the height direction of the equipment body. A metal welded member (for example, two steel plates, not shown) is placed on the table electrode 503 as a workpiece. The pedestal 515 is a table used for welding work, and the table electrode 503 is placed on this pedestal 515.

[0024] The welding transformer 516 supplies power to the vertical gun 502. One electrode (not shown) is connected to the table electrode 503, and the other electrode (not shown) is connected to the power supply device 511 via a power supply cable 517 or the like. The welding transformer 516 is built into the pedestal 515.

[0025] The support arm 514 is disposed at the upper end portion of the upright direction of the support column 513 in a direction perpendicular to the upright direction of the support column 513. The support arm 514 has a multi-joint structure that enables horizontal rotation with the connection portion to the support column 513 as a fulcrum. The control device 518 pressurizes and supplies power to the vertical gun 502 by receiving a welding command by operating a start switch (not shown) disposed on the vertical gun 502. That is, upon receiving a welding command, the control device 518 operates the pressurizing device 510 to pressurize the vertical gun 502 in the direction toward the table electrode 503, and turns on the power supply device 511 to supply power to the vertical gun 502.

[0026] Note that a cooling unit (not shown) is mounted on the resistance welding device 500, and the cooling water circulating inside the resistance welding device 500 is cooled by this cooling unit. The vertical gun 502, the power supply cable 517, etc. have a structure for circulating the cooling water.

[0027] In the resistance welding apparatus 500 configured as described above, when the start switch is operated with the electrode 540 attached to the tip of the vertical gun 502 in contact with the welding point of the workpiece (not shown) disposed on the table electrode 503, the pressurizing device 510 operates and the gun shaft 507 is pushed in the direction toward the workpiece (not shown). At the same time, power is supplied from a power supply unit (not shown) to the welding transformer 516, and the power generated on the secondary side of the welding transformer 516 is applied between the vertical gun 502 and the table electrode 503. Thereby, welding is performed on the workpiece (not shown). At this time, if a projection is formed on the workpiece (not shown), current flows through the projection.

[0028] Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing the appearance of a projection welding member 10 according to an embodiment of the present invention. FIG. 2 is a view of the projection welding member 10 of FIG. 1 as seen from the direction of arrow A. FIG. 3 is a longitudinal sectional view taken along line B-B of the projection welding member 10 of FIG. 1.

[0029] In FIGS. 1 to 3, the projection welding member 10 is used when joining a first steel plate (workpiece, see FIG. 3) 100 and a second steel plate (workpiece, see FIG. 3) 110 by resistance welding.

[0030] The projection welding member 10 includes a first joint portion 11 having an area approximately the same as the area of the first steel plate 100 (the area obtained by multiplying the length in the C direction and the length in the D direction shown in FIG. 1), a second joint portion 12 having an area that contacts one of the two side surfaces 100a and 100b (side surface 100a) in the thickness direction (C direction shown in FIG. 3) of the first steel plate 100 when the first steel plate 100 is applied to the second steel plate 110, a third joint portion 13 having an area that contacts the other of the two side surfaces 100a and 100b (side surface 100b) in the thickness direction (the same C direction as above) of the first steel plate 100 when the first steel plate 100 is applied to the second steel plate 110, a first protrusion 14 that contacts the first steel plate 100 and the second steel plate 110 at one location each in the vicinity of the second joint portion 12 of the first joint portion 11, and a second protrusion 15 that contacts the first steel plate 100 and the second steel plate 110 at one location each in the vicinity of the third joint portion 13 of the first joint portion 11. These members, namely, the first joint portion 11, the second joint portion 12, the third joint portion 13, the first protrusion 14, and the second protrusion 15, are integrally formed.

[0031] The second joint portion 12 contacts the side surface 100a (see FIG. 3) of the first steel plate 100 with its inner surface 12a (see FIG. 2), and the third joint portion 13 contacts the side surface 100b (see FIG. 3) of the first steel plate 100 with its inner surface 13a (see FIG. 2). The second joint portion 12 and the third joint portion 13 support the first steel plate 100. As can be seen from the longitudinal sectional view of FIG. 3, the cross-sections of the first protrusion 14 and the second protrusion 15 are in the shape of abacus beads. The upper vertices of the first protrusion 14 and the second protrusion 15 each contact the bottom surface 100c of the first steel plate 100, and the lower vertices each contact the upper surface 110a of the second steel plate 110.

[0032] The material used for the projection welding member 10 is the same as the materials used for the first steel plate 100 and the second steel plate 110. For example, it is an iron-based material having rigidity and conductivity, or a stainless steel-based material. Incidentally, copper is not very suitable because it is sometimes difficult to melt. Also, magnesium has difficulties in terms of safety, so this is not very suitable either.

[0033] When joining the first steel plate 100 and the second steel plate 110 by resistance welding, a projection welding member 10 having a first joint portion 11 sized according to the thickness of the first steel plate 100 is used and disposed between the first steel plate 100 and the second steel plate 110. At this time, it is disposed such that the width direction (D direction) of the first joint portion 11 is parallel to the width direction of the first steel plate 100. By disposing the projection welding member 10 between the first steel plate 100 and the second steel plate 110, the inner surface 12a of the second joint portion 12 contacts one side surface 100a of the first steel plate 100, and the inner surface 13a of the third joint portion 13 contacts the other side surface 100b of the first steel plate 100.

[0034] Further, the first protrusion 14 contacts the first steel plate 100 and the second steel plate 110 respectively in the vicinity of the second joint portion 12 of the first joint portion 11, and the second protrusion 15 contacts the first steel plate 100 and the second steel plate 110 respectively in the vicinity of the third joint portion 13 of the first joint portion 11.

[0035] In this way, the projection welding member 10 is attached to the first steel plate 100 and applied to the joining position of the second steel plate 110. This assembly is preferably performed on the table electrode 503 of the resistance welding apparatus 500. After this assembly is performed, the electrode 540 is applied to the first steel plate 100. By operating a push-button type start switch (not shown) disposed on the handle 509 of the vertical gun 502 in this state, the control device 518 of the resistance welding apparatus 500 receives a welding command from the start switch and operates the pressurizing device 510 to pressurize the vertical gun 502 in the direction toward the table electrode 503, and further turns on the power supply device 511 to pass a current between the first steel plate 100 and the second steel plate 110.

[0036] The current flowing from the first steel plate 100 to the second steel plate 110 concentrates on the first protrusion 14 and the second protrusion 15 of the projection welding member 10, so that the projection welding member 10 melts, and further melts over the entire contact surface between the first steel plate 100 and the second steel plate 110, and the first steel plate 100 and the second steel plate 110 are joined.

[0037] Thus, according to the projection welding member 10 of the present embodiment, it forms a structure to be attached to the first steel plate 100 and acts as a projection for joining the first steel plate 100 and the second steel plate 110. Therefore, even if the steel plate to be welded is thick, by making the shape according to the thickness, compared with obtaining a projection by processing the steel plate itself as in the conventional case, the projection processing is not required, and the cost can be reduced. That is, it becomes possible to perform welding by projection at low cost.

[0038] In the projection welding member 10 of the present embodiment, the first protrusion 14 is arranged near the second joint portion 12, and the second protrusion 15 is arranged near the third joint portion 13, but it is not necessarily arranged in this way.

[0039] Also, in the projection welding member 10 of the present embodiment, the first protrusion 14 is made to contact the first steel plate 100 and the second steel plate 110 at one place each, but it may be made to contact at a plurality of places. That is, it is sufficient to contact at least at one place. The same applies to the second protrusion 15, and it may be made to contact the first steel plate 100 and the second steel plate 110 at a plurality of places each.

[0040] Also, in the projection welding member 10 of the present embodiment, each of the first protrusion 14 and the second protrusion 15 constituting the projection welding member 10 is formed in a shape of a round head with a flat cross section, but it is not limited to the shape of a round head with a flat cross section as long as the same effect can be obtained. Hereinafter, a modified example of the projection welding member 10 will be described. The projection welding member of this modified example is referred to as a projection welding member 20.

[0041] FIG. 4 is a perspective view showing the appearance of the projection welding member 20. FIG. 5 is a view of the projection welding member 20 in FIG. 4 as seen from the direction of arrow E. FIG. 6 is a longitudinal sectional view taken along line F-F of the projection welding member 20 in FIG. 4. Note that the projection welding member 20 has the same shape as the projection welding member 10 except that the shape of the portion in contact with the first and second steel plates 100 and 110 is different, and thus only the contact portion will be described.

[0042] In FIGS. 4 to 6, the first protrusion 24 contacts the first steel plate 100 and the second steel plate 110 in the vicinity of the second joint 22 of the first joint 21. The second protrusion 25 contacts the first steel plate 100 and the second steel plate 110 in the vicinity of the third joint 23 of the first joint 21.

[0043] The second joint 22 contacts the side surface 100a (see FIG. 6) of the first steel plate 100 with its inner surface 22a (see FIG. 5). The third joint 23 contacts the side surface 100b (see FIG. 6) of the first steel plate 100 with its inner surface 23a (see FIG. 5). The second joint 22 and the third joint 23 support the first steel plate 100. As can be seen from the longitudinal sectional view of FIG. 6, the first protrusion 24 and the second protrusion 25 are formed with a substantially S-shaped cross section. That is, the first protrusion 24 (the second protrusion 25) is formed in an S shape including a convex portion 24a (25a) in contact with the bottom surface 100c of the first steel plate 100 and a convex portion 24b (25b) in contact with the upper surface 110a of the second steel plate 110 at a distance from the convex portion 24a (25a).

[0044] When joining the first steel plate 100 and the second steel plate 110 by resistance welding, a projection welding member 20 having a first joint portion 21 sized according to the thickness of the first steel plate 100 is used and disposed between the first steel plate 100 and the second steel plate 110. At this time, it is disposed such that the width direction of the first joint portion 21 is parallel to the width direction of the first steel plate 100. By disposing the projection welding member 20 between the first steel plate 100 and the second steel plate 110, the inner surface 22a of the second joint portion 22 contacts one side surface 100a of the first steel plate 100, and the inner surface 23a of the third joint portion 23 contacts the other side surface 100b of the first steel plate 100.

[0045] Also, the first protrusion 24 contacts the first steel plate 100 and the second steel plate 110 respectively near the second joint portion 22 of the first joint portion 21, and the second protrusion 25 contacts the first steel plate 100 and the second steel plate 110 respectively near the third joint portion 23 of the first joint portion 21.

[0046] In this way, the projection welding member 20 is attached to the first steel plate 100 and applied to the joining position of the second steel plate 110. After this assembly is performed, an electrode 540 is applied to the first steel plate 100. In this state, by operating a push-button type start switch (not shown) disposed on the handle 509 of the vertical gun 502, the control device 518 of the resistance welding apparatus 500 receives a welding command from the start switch and operates the pressurizing device 510 to pressurize the vertical gun 502 in the direction toward the table electrode 503, and further turns on the power supply device 511 to pass a current between the first steel plate 100 and the second steel plate 110.

[0047] The current flowing from the first steel plate 100 to the second steel plate 110 concentrates on the first protrusion 24 and the second protrusion 25 of the projection welding member 20, so that the projection welding member 20 melts, and further melts over the entire contact surface between the first steel plate 100 and the second steel plate 110, and the first steel plate 100 and the second steel plate 110 are joined.

[0048] Thus, according to the projection welding member 20 of the present embodiment, since it has a structure for being attached to the first steel plate 100 and acts as a projection for joining the first steel plate 100 and the second steel plate 110, even if the steel plate to be welded is thick, by making it into a shape corresponding to the thickness, compared with obtaining a projection by processing the steel plate itself as in the prior art, the projection processing is not required, and the cost can be reduced. That is, it becomes possible to perform welding by projection at low cost.

[0049] Although the present invention has been described with reference to specific embodiments, it is obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention.

Industrial Applicability

[0050] The present invention can be applied to a resistance welding apparatus that sandwiches a plate assembly formed by overlapping two steel plates between two electrodes, energizes while applying pressure, and performs welding.

Explanation of Reference Numerals

[0051] 10, 20 Projection welding member 11, 21 First joint 12, 22 Second joint 13, 23 Third joint 14, 24 First protrusion 15, 25 Second protrusion 100 First steel plate 110 Second steel plate 500 Resistance welding apparatus 502 Vertical gun 503 Table electrode 509 Handle 518 Control device 510 Pressurizing device 511 Power supply device 540 Electrode

Claims

【Claim 1】 It is used when joining a first steel plate and a second steel plate by resistance welding, a first joint portion having an area approximately the same size as the contact surface when the first steel plate is applied to the second steel plate, a second joint portion having an area of a size that contacts one of the two side surfaces in the thickness direction of the first steel plate when the first steel plate is applied to the second steel plate, a third joint portion having an area of a size that contacts the other of the two side surfaces in the thickness direction of the first steel plate when the first steel plate is applied to the second steel plate, a first protrusion provided near the second joint portion of the first joint portion and contacting at least one location on each of the first steel plate and the second steel plate, a second protrusion provided near the third joint portion of the first joint portion and contacting at least one location on each of the first steel plate and the second steel plate, and comprising, wherein the first joint portion, the second joint portion, the third joint portion, the first protrusion, and the second protrusion are integrally formed, a projection welding member.

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