Welding electrode holder

Abstract

To provide a welding electrode holder with adjustable cooling pipe position. [Solution] A welding electrode holding device comprising a cylindrical holder on which an electrode tip or a shank with an electrode tip attached is mounted at one end, and a cooling pipe inserted into the cylindrical holder, wherein the inside of the cooling pipe serves as a cooling water supply passage, and the space between the outside of the cooling pipe and the inside of the cylindrical holder serves as a return passage, wherein a slide pipe through which the cooling pipe is inserted is slidably arranged inside the cooling pipe, the base end of the slide pipe is attached to a support member, and a cooling water supply joint and a discharge joint are attached to the support member, and a lock nut through which the slide pipe is inserted is rotatably screwed onto the other end of the cylindrical holder, and a sleeve that expands or contracts in diameter as the lock nut rotates is arranged inside the lock nut.

Description

Technical Field

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[0001] The present invention relates to an electrode holding device capable of cooling a welding electrode (tip), particularly to one provided with an adjuster mechanism for a cooling pipe.

Background Art

[0002] In spot welding, when welding a workpiece such as a steel plate, the workpiece is sandwiched between upper and lower electrode tips and current is passed through, melting the workpiece with the heat generated by electrical resistance for welding. As the number of shots increases, the tip of the electrode tip wears, the contact area with the workpiece increases, the current density decreases, and welding defects occur. Therefore, conventionally, in order to reduce the wear of the electrode tip, the electrode tip is cooled by cooling water.

[0003] The structure for cooling the electrode tip is to attach the electrode tip directly or via a shank to the tip of a cylindrical holder, and to flow cooling water from the tip of a cooling water pipe disposed inside the cylindrical holder inside the electrode tip.

[0004] Depending on the shape of the workpiece, the lengths of the shank and the electrode tip are different. In such a case, if only the shank and the electrode tip are replaced, the tip of the cooling pipe does not reach sufficiently close to the vicinity of the electrode tip, resulting in insufficient cooling. Also, replacing the entire holding jig equipped with not only the electrode but also the cooling pipe in order to perform sufficient cooling takes time and labor for replacement, and there is a lot of waste.

[0005] Therefore, in Patent Document 1, the cooling pipe disposed inside the cylindrical holder constituting the electrode holding device is made movable, and the protruding amount of the cooling pipe from the tip of the cylindrical holder can be adjusted.

[0006] Two structures are disclosed in the above Patent Document 1 as structures for adjusting the protruding amount of the cooling pipe. The first structure involves inserting a cooling pipe into a cylindrical holder, with the cooling pipe serving as a cooling water supply path, and the space between the outside of the cooling pipe and the inside of the cylindrical holder serving as a cooling water return path. A support member that supports the base end of the cooling pipe is slidably fitted into the base of the cylindrical holder, and an axially elongated groove is formed on the circumferential surface of the support member. A set bolt attached to the cylindrical holder is engaged with this elongated groove, allowing the cooling pipe to be positioned within the cylindrical holder by loosening the set bolt, and fixing the position of the cooling pipe by tightening the set bolt.

[0007] The second structure disclosed in Patent Document 1 divides the cooling pipe support member of the first structure into a base portion and a fixing portion, inserts the cooling pipe slidably into the fixing portion, attaches a nut member to the fixing portion, fits a ring ball onto the outer circumference of the cooling pipe, and adjusts the position of the cooling pipe by loosening or tightening the ring ball by operating the nut member. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Patent No. 7350267 [Overview of the project] [Problems that the invention aims to solve]

[0009] In the first structure of Patent Document 1, the cooling pipe is prevented from moving by simply pressing the tip of the retaining bolt against the long groove. However, vibrations can loosen the retaining bolt, causing the cooling pipe to become unstable.

[0010] In the second structure of Patent Document 1, since the ring ball with a changing diameter is directly fitted to the outer surface of the cooling pipe, if the nut member is not tightened properly, the cooling pipe may fall out, or if the nut member is overtightened, the ring ball may deform and the cooling pipe may become immobile.

[0011] Furthermore, in both the first and second structures, the cooling water supply joint and discharge joint are attached separately to different components, particularly two components whose spacing changes depending on the position of the cooling pipe. In the first structure, they are attached to a cylindrical holder and a support member, while in the second structure, they are attached to the base portion and fixing member that constitute the support member. Therefore, adjusting the position of the cooling pipe also changes the spacing between the supply joint and the discharge joint. Consequently, the cooling water supply side needs to have a corresponding structure. [Means for solving the problem]

[0012] To solve the above problems, the present invention provides a welding electrode holding device comprising a cylindrical holder on which an electrode tip or a shank with an electrode tip attached is mounted at one end, and a cooling pipe inserted into the cylindrical holder, wherein the inside of the cooling pipe serves as a cooling water supply passage, and the space between the outside of the cooling pipe and the inside of the cylindrical holder serves as a return passage, wherein a slide pipe through which the cooling pipe is inserted is slidably arranged inside the cooling pipe, the base end of the slide pipe is attached to a support member, and a cooling water supply joint and a discharge joint are attached to the support member, and a lock nut through which the slide pipe is inserted is rotatably screwed onto the other end of the cylindrical holder, and a sleeve that expands or contracts in diameter as the lock nut rotates is arranged inside the lock nut.

[0013] It is preferable to apply nickel plating to the outer surface of the cylindrical holder described above to prevent spatter from adhering to it. [Effects of the Invention]

[0014] In this invention, even when replacing with a different type of electrode tip (shank), the protrusion amount of the cooling pipe can be adjusted accordingly, allowing for optimal electrode cooling, reducing electrode wear, and avoiding welding defects.

[0015] Further, according to the present invention, it is possible to effectively prevent leakage of cooling water, and since the distance between the supply joint and the discharge joint of the cooling water does not change even when the cooling water pipe moves, the structure on the supply side of the cooling water does not become complicated either.

Brief Description of Drawings

[0016] [Figure 1] Overall view of a welding apparatus to which a welding electrode holding device according to the present invention is applied [Figure 2] Perspective view of the welding electrode holding device [Figure 3] Cross-sectional view of the welding electrode holding device, where (a) shows a state where the protruding amount of the cooling water pipe is increased, and (b) shows a state where the protruding amount of the cooling water pipe is decreased. [Figure 4] (a) is a side view of the lock nut, and (b) is a longitudinal cross-sectional view of the lock nut [Figure 5] Perspective view of the sleeve [Figure 6] (a) and (b) are cross-sectional views explaining the usage state

Modes for Carrying Out the Invention

[0017] As shown in FIG. 1, an upper support portion 2 and a lower support portion 3 project forward from the welding machine main body 1. An arm 4 is supported by the lower support portion 3, and a welding electrode holding device 5 according to the present invention is held by this arm 4, and a lower electrode 6 is attached to this welding electrode holding device 5.

[0018] An arm 8 is supported by the upper support portion 2 via a vertical cylinder unit 7, and a welding electrode holding device 5 (with the vertical direction reversed from the lower part) is held by this arm 8, and an upper electrode (cap tip) 9 is attached to this welding electrode holding device 5.

[0019] As shown in FIGS. 2 to 5, in the welding electrode holding device 5, a cylindrical slider 11 is slidably arranged in a cylindrical holder 10, and the inner side surface of the tip portion of the cylindrical holder 10 is a female tapered surface for mounting a shank or an electrode tip.

[0020] The cooling pipe 12 penetrates through the inner parts of the cylindrical holder 10 and the cylindrical slider 11. This cooling pipe 12 is fixed to the support member 13, and this support member 13 is screwed to the cylindrical slider 11. As a result, the cooling pipe 12 is integrated with the cylindrical slider 11. Further, a water supply joint 14 and a discharge joint 15 for cooling water are attached to the support member 13.

[0021] The cooling water supplied from the supply joint 14 passes through the supply path inside the cooling pipe 12 and jets out near the electrode chip (shank) attached to the tip of the cylindrical holder 10 to cool the electrode chip (shank). The cooled cooling water is discharged from the discharge joint 15 through the return path between the outside of the cooling pipe 12 and the inside of the cylindrical holder 10 and the cylindrical slider 11.

[0022] A lock nut 16 is rotatably screwed to the base end portion of the cylindrical holder 10. The cylindrical slider 11 passes through the lock nut 16, and recesses 17 for facilitating the rotation operation are formed at three spaced positions on the peripheral surface of the lock nut 16 as shown in FIGS. 2 and 4, so that it can be tightened by hand without using a tool.

[0023] As shown in its cross-sectional view, an internal female tapered surface 18 is formed on the inner part of the lock nut 16, and a sleeve 19 is arranged inside the lock nut 16 as shown in FIG. 5. A male tapered surface 20 corresponding to the female tapered surface 18 is formed on this sleeve 19. The angles (both angles) of these female tapered surface 18 and male tapered surface 20 are preferably 25 to 55°. Further, a slit 21 for facilitating the reduction and expansion of the diameter is formed on the sleeve 19.

[0024] Also, a retaining ring 22 is attached to the outer periphery of the tip of the cylindrical slider 11. This ring 22 is for preventing the cylindrical slider 11 from falling off the cylindrical holder 10 due to the pressure of the cooling water by locking the ring 22 to the sleeve 19 in the state where the cylindrical slider 11 has come out of the cylindrical holder 10 most as shown in FIG. 3(b).

[0025] In the above configuration, when the lock nut 16 is rotated to the left from the state shown in Figure 3(a), the lock nut 16 screws downward in the figure. As the lock nut 16 moves downward, the sleeve 19 is released from its constrained state between the cylindrical holder 10 and the female tapered surface 18 of the lock nut 16, and expands in diameter.

[0026] As the sleeve 19 expands in diameter, the cylindrical slider 11 becomes movable, and the cooling pipe 12, which is integrated with the cylindrical slider 11, also becomes movable, allowing the amount of protrusion from the cylindrical holder 10 to be changed.

[0027] After adjusting the amount of protrusion of the cooling pipe 12 from the cylindrical holder 10, the lock nut 16 is rotated to the right. The lock nut 16 then screws upward, and the sleeve 19 also moves upward, but when it hits the end of the cylindrical holder, its upward movement is prevented, and then the female tapered surface 18 and the male tapered surface 20 come into contact, so the sleeve 19 shrinks in diameter and the movement of the cylindrical slider 11 is locked.

[0028] Figure 6 shows the state in which the amount of protrusion of the cooling water pipe 12 from the cylindrical holder 10 is adjusted to correspond to the difference in electrode length. In this embodiment, (a) is used as a holding device for the upper electrode and (b) is used as a holding device for the lower electrode. [Industrial applicability]

[0029] The welding electrode holding device according to the present invention is effective in the manufacture of automobile parts, but is not limited to this and can be used in any field that requires parts in which materials to be welded, such as nuts and bolts, are welded to a plate material. [Explanation of Symbols]

[0030] 1...Welding machine body, 2...Upper support part, 3...Lower support part, 4, 8...Arms, 5...Welding electrode holder, 6...Lower electrode, 7...Cylinder unit, 9...Upper electrode, 10...Cylindrical holder, 11...Cylindrical slider, 12...Cooling pipe, 13...Support member, 14...Cooling water supply joint, 15...Cooling water discharge joint, 16...Lock nut, 17...Recess, 18...Female tapered surface, 19...Sleeve, 20...Male tapered surface, 21...Slit, 22...Retaining ring.

Claims

1. A welding electrode holding device comprising a cylindrical holder on which an electrode tip or a shank with an electrode tip attached is mounted at one end, and a cooling pipe inserted into the cylindrical holder, wherein the inside of the cooling pipe serves as a cooling water supply passage, and the space between the outside of the cooling pipe and the inside of the cylindrical holder serves as a return passage, wherein a slide pipe through which the cooling pipe is inserted is slidably arranged inside the cooling pipe, the base end of the slide pipe is attached to a support member, and a cooling water supply joint and a discharge joint are attached to the support member, and a lock nut through which the slide pipe is inserted is rotatably screwed onto the other end of the cylindrical holder, and a sleeve that expands or contracts in diameter as the lock nut rotates is arranged inside the lock nut.

2. A welding electrode holding device with a cooling mechanism according to claim 1, characterized in that a retaining ring is attached to the tip of the slide pipe.

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