Two-point upper electrode unit

Abstract

To provide a two-point upper electrode unit in which the contact points of the electrode tip of the lower electrode unit and the electrode tip of the upper electrode unit to a workpiece do not shift during welding. [Solution] With the upper tracing surface 26 of the oscillating member 23 abutting against the concave guide surface 25 of the holding member and the undersides of both ends of the oscillating member 23 abutting against the upper end of the adapter 17 that holds a pair of electrode tips 8, 8, an upper gap g1 and a lower gap g2 are formed between the horizontal shaft 22 and the inner surface of the elongated hole 24, so that a slight amount of relief is created in the vertical direction, and even if resistance or snagging occurs in the movement of the adapter, this can be absorbed by the movement of the oscillating member 23 without the electrode holder 15 tilting.

Description

[Technical Field]

[0001] The present invention relates to an upper electrode unit that simultaneously spot welds two locations on a workpiece (an object to be welded). [Background technology]

[0002] Conventionally, in order to increase the efficiency of spot welding, multiple locations on a workpiece have been spot-welded simultaneously.

[0003] Patent Document 1 describes that an adjustment piece is stored inside an electrode holder, an inclined surface is formed on the side of this adjustment piece, and an inclined surface of the same angle that contacts this inclined surface is formed on the head of the electrode, and when there is a convex portion on the workpiece, the tip of one electrode abuts on the convex portion and then the electrode holder is further lowered, one electrode enters the electrode holder and the head raises the adjustment piece while moving toward the other electrode, and the tip of the other electrode abuts on the workpiece, and when the electrode holder is further lowered, the electrode is drawn into the electrode holder and assumes a state for welding.

[0004] Patent Document 2 discloses a structure in which a spherical head is formed at the tip of an arm, and a hemispherical receiving recess of an electrode holder is fitted into this spherical head to enable it to swivel. Even if the tip positions of multiple electrodes do not coincide with the abutment position of the workpiece, the electrode holder slides along the workpiece, and the tips of the electrodes abut against the workpiece, welding multiple points simultaneously.

[0005] Patent document 3 discloses a structure in which a tilting member is tiltably attached to a fixed member via an axial member, a shank is slidably attached to a mating protrusion formed on the tilting member, and multiple electrodes are attached to this shank, thereby enabling position adjustment in the vertical and horizontal directions.

[0006] Patent Document 4 discloses a structure in which a swivel joint is attached to an electrode body so as to be able to swing freely, and an electrode tip is attached to this swivel joint via two shanks. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6794594 [Patent Document 2] Patent No. 5455112 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-179318 [Patent Document 4] Japanese Patent Application Laid-Open No. 2003-80371 Summary of the Invention [Problem to be solved by the invention]

[0008] FIG. 7 shows an outline of a conventional electrode device, in which an upper electrode unit 100 and a lower electrode unit 200 each have two electrode tips 101, 201, and the upper electrode unit 100 has the electrode tips 101, 101 held by an electrode holder 104 that swings in a vertical plane around a horizontal axis 103.

[0009] If the electrode holder 104 is misaligned by just 1° from the vertical position, the contact points of the upper electrode tip 101 and the lower electrode tip 201 with the workpiece will be significantly misaligned. The electrode holder 104 corresponds to an adjustment piece in Patent Document 1, an electrode holder in Patent Document 2, a tilting member in Patent Document 3, and a swivel joint in Patent Document 4.

[0010] All of the prior art disclosed in Patent Documents 1 to 4 devise ways to prevent the upper electrode tip and the lower electrode tip from misaligning, but these are not sufficient, which results in poor welding and, further, uneven wear of the electrode tips, shortening the life of the electrodes. [Means for solving the problem]

[0011] In order to solve the above problems, the upper electrode unit of the present invention has a structure in which a pair of electrode tips, which spot weld two points on a workpiece simultaneously, are held via adapters in through holes formed in the electrode holder so that they can slide freely in the vertical direction, the electrode holder is attached to a support connected to a holding member, a oscillating member is attached to this support via a horizontal shaft, the upper ends of the adapters of the pair of electrode tips abut against the undersides of both ends of the oscillating member, a copying surface that fits the guide surface formed on the holding member is formed on the upper surface of the oscillating member, and gaps are formed at the top and bottom between the horizontal shaft and an engagement hole formed in the oscillating member that engages with the horizontal shaft.

[0012] The outer periphery of the adapter and at least a portion of the through hole may be made rectangular or other non-cylindrical shape, which prevents the adapter from rotating within the through hole and prevents the cooling water passage formed in the adapter from becoming misaligned. It also serves as a locking mechanism when removing the electrode tip. [Effects of the Invention]

[0013] In the present invention, even if one of the pair of electrode tips hits the workpiece first, for example, when the grinding length of the electrode tips is not constant, the electrode tip that hits first moves up and down vertically on its own. Therefore, the contact points of the electrode tip of the lower electrode unit and the electrode tip of the upper electrode unit with the workpiece do not shift during welding, and pressure is applied uniformly, resulting in stable welding quality.

[0014] In addition, the electrode tip does not wear out unevenly, extending its lifespan. Furthermore, by making the electrode holder out of insulating materials such as resin, electrolytic corrosion can be prevented. [Brief explanation of the drawings]

[0015] [Figure 1] Overall view of a welding device incorporating a two-point upper electrode unit according to the present invention. [Figure 2] Perspective view of the two-point upper electrode unit [Figure 3] Bottom view of the two-point upper electrode unit [Figure 4] Side view of the two-point upper electrode unit [Figure 5] Cross section of line AA in Figure 4 [Figure 6] Detailed view of the swinging member [Figure 7] A diagram explaining the problems with conventional two-point hitting DETAILED DESCRIPTION OF THE INVENTION

[0016] As shown in Figure 1, an upper support section 2 and a lower support section 3 extend forward from a welding machine body 1, a horizontal arm 5 is held by the upper support section 2 via a cylinder unit 4, and an upper electrode unit 7 is attached to this horizontal arm 5 via a holding member 6. This upper electrode unit 7 holds a pair of electrode tips 8 for spot welding two locations on a workpiece W simultaneously.

[0017] An arm 9 is supported on the lower support part 3, and a lower electrode unit 11 is attached to this arm 9 via a holding member 10, and this lower electrode unit 11 holds a pair of electrode tips 12 that pressurize the workpiece W between the pair of electrode tips 8 and weld it.

[0018] The upper electrode unit 7 will be described in detail with reference to Figures 2 to 6. The upper electrode unit 7 holds a holding member 6 between two aluminum supports 13 and 14, and also holds an electrode holder 15 made of an insulating material such as resin.

[0019] Two vertical through holes 16 are formed in the electrode holder 15, and an adapter 17 that holds the electrode tip 8 is slidably inserted into these through holes 16. The lower end portions of the through holes 16 and the adapter 17 are square, so that the adapter 17 does not rotate within the through hole 16 when sliding up and down.

[0020] A stopper ring 17a is attached to the upper end of the adapter 17 to prevent it from coming loose. This stopper ring 17a also has the function of preventing wear powder generated by contact with the oscillating member (described later) from entering the through hole 16, thereby avoiding malfunctions.

[0021] The electrode holder 15 and the adapter 17 are formed with a cooling water supply path 18 and a drain path 19, and a water stop ring is placed on the inner surface of the through hole 16 to prevent water leakage between the electrode holder 15 and the adapter 17. Furthermore, the presence of the water stop ring maintains the vertical movement of the adapter 17 and suppresses wear on the upper tracing surface 26 of the oscillating member 23 and the concave guide surface 25 of the holding member.

[0022] Cooling water is supplied to a supply path 18 from a joint 20 attached to the front surface of the electrode holder 15, passes through a cooling water discharge path 19 and is discharged from a joint 21.

[0023] A horizontal shaft 22 is provided between the supports 13 and 14 above the electrode holder 15, and a swinging member 23 is supported on this horizontal shaft 22. This swinging member 23 engages with the horizontal shaft 22 via a vertically elongated hole 24 formed in the center, and the lower surfaces of both ends abut against the upper end of the adapter 17. In this state, an upper gap g1 and a lower gap g2 are formed between the horizontal shaft 22 and the inner peripheral surface of the elongated hole 24.

[0024] A concave guide surface 25 is formed on the lower surface of the holding member 6, and a convex profiling surface 26 that fits into the concave guide surface 25 is formed on the upper surface of the swinging member 23. Therefore, the swinging member 23 swings around the horizontal shaft 22 without shifting left or right when swinging.

[0025] In FIG. 6, O1 is the center of the convex profiling surface 26, O2 is the center of the upper arc of the elongated hole 24, and O3 is the center of the lower arc of the elongated hole 24. The distance between O1 and O2 and the distance between O1 and O3 do not have to be the same.

[0026] The elongated hole 24 has a shape in which an upper semicircle and a lower semicircle are connected by a straight line, and the lower surfaces of the left and right ends of the swinging member 23 that abut against the upper end of the adapter 17 form downward convex portions 27.

[0027] In the above, when spot welding the workpiece W (two steel plates) using the upper electrode unit 7 and the lower electrode unit 11, if the protruding dimensions of the pair of electrode tips 8, 8 held by the upper electrode unit 7 from the electrode holder 15 are different, the electrode tip 8 with the larger protruding dimension will come into contact with the workpiece first.

[0028] When the electrode tip 8 with the larger protrusion dimension comes into contact with the workpiece, the electrode tip 8 slides vertically together with the adapter 17, and as a result, the oscillating member 23 oscillates around the horizontal axis 22, and this oscillation pushes down the electrode tip 8 with the smaller protrusion dimension, until the pair of electrode tips 8 come into contact with the workpiece with the same protrusion amount.

[0029] In particular, in the case of the present invention, when the upper copying surface 26 of the swinging member 23 abuts against the concave guide surface 25 of the holding member and the lower surfaces of both ends of the swinging member 23 abut against the upper end of the adapter 17 that holds the pair of electrode tips 8, 8, an upper gap g1 and a lower gap g2 are formed between the horizontal shaft 22 and the inner circumferential surface of the elongated hole 24, so that a slight amount of relief is formed in the vertical direction, and even if resistance or snagging occurs in the movement of the adapter, this can be absorbed by the movement of the swinging member 23 without tilting the electrode holder 15. Therefore, the problem described in Figure 7 does not occur. [Industrial Applicability]

[0030] The two-spot upper electrode unit 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 made by spot welding two pieces of workpiece material. [Explanation of symbols]

[0031] 1...welding machine body, 2...upper support part, 3...lower support part, 4...cylinder unit, 5, 9...arm, 6, 10...holding member, 7...upper electrode unit, 11...lower electrode unit, 8, 12...electrode tip, 13, 14...support, 15...electrode holder, 16...through hole, 17...adapter, 17a...stopper ring, 18...cooling water supply path, 19...cooling water discharge path, 20, 21...joint, 22...horizontal shaft, 23...oscillating member, 24...long hole, 25...concave guide surface, 26...convex tracing surface, 27...downward convex part, g1, g2...gap, W...work.

Claims

1. 1. An upper electrode unit having a pair of electrode tips for spot welding two points on a workpiece simultaneously, characterized in that an adapter for holding the pair of electrode tips is slidably held in a vertical through hole formed in an electrode holder, the electrode holder is attached to a support connected to a holding member, a swing member is attached to this support via a horizontal shaft, upper ends of the adapters for holding the pair of electrode tips abut against lower surfaces at both ends of the swing member, a copying surface is formed on the upper surface of the swing member that fits with the guide surface formed on the holding member, and gaps are formed at the top and bottom between the horizontal shaft and an engagement hole formed in the swing member that engages with the horizontal shaft.

2. 2. The two-point upper electrode unit according to claim 1, wherein at least a portion of the outer periphery of an adapter for holding said pair of electrode tips is non-cylindrical.

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