JPH0910954A - Resistance welding gun - Google Patents

Abstract

(57) [Summary] [Purpose] To facilitate the repair of welding guns and enhance their effectiveness. [Structure] A pair of yokes 1, 2 rotatably provided on the same main shaft 3 via bearings 15 are sandwiched by a gun bracket 11 to form a rotary shaft portion 7. An insulating member having at least the same wear resistance as that of the pair of yokes and the gun bracket on the sliding contact surfaces 1a, 2a and 11a of the pair of yokes 1 and 2 and one of the pair of yokes and the gun bracket 11. 16 is detachably attached. The actual sliding contact surface in the opening / closing operation of the pair of yokes 1 and 2 is composed of the insulating members 16, and the wear caused by the above-mentioned operation is positively generated only in the insulating members 16. Therefore, the main components themselves such as the pair of yokes 1 and 2 and the gun bracket 11 in the rotary shaft portion 7 of the welding gun maintain a regular shape, and at the time of repairing, the insulating member 16 is simply replaced, and the same as new. It is possible to return to the state of.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a rotary shaft portion for coaxially supporting a pair of yokes in a resistance welding gun through an insulating member.

[0002]

2. Description of the Related Art Resistance welding uses the resistance heat generated by applying a pressure of about 200 to 300 kgf to the material to be welded by opposing electrodes provided on the welding gun and applying a large current for a short time. , For joining materials to be welded. As shown in FIG. 3, the welding gun has a pair of yokes, an upper yoke 1 and a lower yoke 2, each of which opens and closes around a main shaft 3. Arms 5 and 6 provided with electrodes 4 are attached to the respective tip portions of the upper yoke 1 and the lower yoke 2 so as to face each other.

FIG. 4 shows the structure of the rotary shaft portion 7 of the upper and lower yokes 1 and 2 having the main shaft 3 as a rotary shaft. As described above, the upper yoke 1 and the lower yoke 2 share the main shaft 3, and each is rotatably supported by the main shaft 3 via the bearing 8. Further, a thread groove is formed at the tip of the main shaft 3,
It is fixed to the gun bracket 11 by the nut 10 via the washer 9. Further, a washer-shaped insulating member 12 is interposed between the sliding contact surfaces 1a and 2a between the upper yoke 1 and the lower yoke 2 and between the sliding contact surfaces 2a and 11a between the lower yoke 2 and the gun bracket 11. I am letting you. The insulating member 12 is made up of two pins 13 so that the upper yoke 1, the lower yoke 2 or the gun bracket
Fixed to 11. An insulating bush 14 is also interposed between the bearing 8 and the upper and lower yokes 1, 2.

The reason why the upper yoke 1 and the lower yoke 2 are insulated in this way is that if the upper yoke 1 and the lower yoke 2 are short-circuited in the rotating shaft portion 7, they are provided at the tips of the arms 5 and 6. This is because the electrodes 4 are not energized and welding cannot be performed. Therefore, the insulating member 12 and the insulating bush 14 are indispensable to the rotating shaft portion 7 of the welding gun.

[0005]

However, the welding gun having the above structure has the following drawbacks. As described above, when performing resistance welding, the electrode 4 applies a pressure of about 200 to 300 kgf to the material to be welded. The reaction force of the applied pressure is concentrated on the main shaft 3 via the arms 5 and 6 and the upper and lower yokes 1 and 2. Therefore, the sliding contact surface S between the upper and lower yokes 1 and 2 and the insulating bush 14
_A large load is applied to ₁ and S ₂ . Also, during welding, the electrode 4
When an eccentric load is applied to the upper and lower yokes 1, 2
A large load is applied to the sliding contact surface S ₃ between the main shaft 3 and the gun bracket 11 when the welding gun itself moves.
Due to the above reasons, the sliding contact surfaces of S ₁ , S ₂ and S ₃ are likely to be worn.

When the wear progresses, metal particles called "scatter" scattered from the welded portion of the member to be welded and cooling water used to suppress the temperature rise of the electrode 4 are rotated.
This may cause troubles such as entering the inside and corroding the bearing 8, or entering the inside of the bearing 8 and damaging the rotating mechanism of the bearing 8. Under these circumstances, the sliding contact surfaces S ₁ , S ₂ and S ₃ are further worn, and the sectional shape of the main shaft 3, the bearing mounting holes of the upper and lower yokes 1 and 2 and the main shaft mounting hole of the gun bracket 11 are increased. May be transformed into an oval.

Further, the insulating member 12 and the upper and lower yokes 1, 2
And sliding contact surfaces 1a, 2a and 11 with the gun bracket 11
In addition to the wear that occurs when the upper and lower yokes 1 and 2 are opened and closed, the above dust spreads into the a, causing further wear. Therefore, the upper and lower yokes 1, 2
Further, a gap is formed on each sliding contact surface between the gun bracket 11 and the insulating member 12, and the rotary shaft portion 7 is loosened (played). The looseness of the rotating shaft portion 7 appears as a displacement of the pressure contact of the two electrodes 4, and has a great adverse effect on the welding quality.

At present, in order to correct this looseness,
The nut 10 is temporarily tightened by tightening it further. Also, as a permanent measure, wear insulating members
In consideration of the wear amounts of the upper and lower yokes 1 and 2, and the gun bracket 11, the 12 is replaced with an insulating member having an increased thickness from the beginning, and the clearance is filled. 2 and the large amount of man-hours required to measure the dimensions of the gun bracket 11, etc., but considering the uneven wear of each member, the actual amount of slack and the increased thickness of the insulating member should match. Can't expect. Therefore, not a little looseness remains. If the welding work is continued with the looseness left, the wear of the respective parts will immediately progress.

In addition, it is necessary to disassemble and apply to the processing machine to correct the deformed sectional shape of the main shaft 3, the bearing mounting holes of the upper and lower yokes 1 and 2, and the main shaft mounting hole of the gun bracket 11. It was not possible to provide first aid with the product installed in the welding line. Further, minute wear may be overlooked during inspection, and the service life of the welding gun after repairing may be reduced to 1/3 that of a new product. Therefore, even if the above-mentioned modification is applied, it is not possible to obtain an effect commensurate with the number of man-hours, cost, and the like.

The present invention has been made in view of the above problems, and an object thereof is to provide a sliding contact surface of a main component such as a pair of yokes and a gun bracket in a rotating shaft portion of a welding gun. By intentionally providing an insulating member having wear resistance at least equal to or less than that of the main component so as to be detachable, and causing wear only to the insulating member having low wear resistance, the main component itself Is to keep the regular shape.

[0011]

Means for Solving the Problems According to the present invention for solving the above problems, a pair of yokes rotatably provided on the same main shaft via bearings are sandwiched between gun brackets. An insulating member that forms a rotary shaft portion and has at least equal wear resistance to the pair of yokes and each sliding contact surface between one of the pair of yokes and the gun bracket, as compared with the pair of yokes and the gun bracket. Is installed.

[0012]

The pair of yokes and one of the pair of yokes and each of the sliding contact surfaces of the gun bracket are provided with an insulating member whose wear resistance is at least equal to or less than that of the pair of yokes and the gun bracket. An actual sliding contact surface at the time of opening / closing operation of the yoke is configured such that these insulating members contact each other.
Then, the wear caused by the welding operation is generated only in the insulating member having low wear resistance.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the accompanying drawings. In the figure, the same or corresponding parts as those of the conventional example are denoted by the same reference numerals, and detailed description is omitted.

FIG. 1 shows a sectional view of the rotary shaft portion 7 of the welding gun. The base end portions of the upper yoke 1 and the lower yoke 2 are
Both are rotatably supported on the main shaft 3 via a radial roller bearing 15 (hereinafter, simply referred to as a bearing). Further, as the structure of this embodiment, the outer surface of the base end portion of the lower yoke 2 is sandwiched by the gun brackets 11. further,
An insulating bush 14 is interposed between the upper and lower yokes 1 and 2 and the bearing 15. The insulating bush 14 is fixed to the bearing 15 by hammering, screwing or the like, and is easily attached and detached. Spindle mounting hole for gun bracket 11 111
A bush 20 is interposed between the bush 20 and the main shaft 3. The bush 20 is press-fitted into the spindle mounting hole 111 or attached by an engaging member such as a pin or a screw, and is removable. Further, sliding contact surfaces 1a, 2 between the upper yoke 1 and the lower yoke 2
a and sliding contact surface 2 between lower yoke 2 and gun bracket 11
A washer-shaped insulating member 16 is detachably attached to each of a and 11a by using an engaging member 17 such as a pin or a screw.

By the way, as the material used for the main shaft 3, generally, a carbon steel steel for machine structural use such as S45C which has been subjected to a heat treatment is subjected to hard chrome plating or the like and has high wear resistance and rust prevention ability. For the upper and lower yokes 1 and 2,
High-strength brass and beryllium-copper alloy are used. Insulation bush
For 14, an acetal resin, a nylon resin, or the like is used.

The material used for the insulating member 16 is a resin material such as acetal resin, nylon resin, insulating oil-impregnated metal, insulating metal, or a combination thereof.

A grease path 18 is provided on the main shaft 3. The grease path 18 has an opening at one end of the main shaft,
A main path 18a extending in the axial direction and a sub-path 18b branching from the main path 18a in the radial direction to reach the main shaft surface are provided so that each bearing 15 can be lubricated. Further, a grease chamber 19 capable of storing grease is formed between the bearings 15 that support the upper yoke.

The operation and effect obtained from the first embodiment of the present invention having the above structure will be described below. As mentioned above,
An insulating member is provided on each of the sliding contact surfaces 1a, 2a and 11a of the lower yokes 1 and 2 and the lower yoke 2 and the gun bracket 11, respectively.
16 is installed. Therefore, the actual sliding contact surface in the opening / closing operation of the upper and lower yokes 1 and 2 is composed of insulating members 16 having at least equal wear resistance as compared with the upper and lower yokes 1 and 2 and the gun bracket 11. To be done. Therefore, by positively causing the wear caused by the welding operation only to the insulating member 16, the upper and lower yokes 1 and 2 and the gun bracket 11 which are the main components of the welding gun can maintain their regular shapes. it can.

Moreover, since the insulating member 16 is removable, by replacing only the insulating member 16 before the looseness of the rotary shaft portion 7 exceeds the allowable range, the same assembly dimensional accuracy as a new product is maintained. It is possible to return to a state without looseness. Therefore, it becomes easy to always maintain a state of no looseness, and scattering of foreign matter such as cooling water or the like into the rotating shaft portion 7 can be suppressed as much as possible. Further, the grease supplied from the grease passage 18 and the grease chamber 19 described above constantly lubricates the bearing 15 to suppress the occurrence of troubles in the bearing 15, thereby preventing the main shaft 3 from being deformed and
It is possible to prevent the deformation of the bearing mounting holes of the lower yokes 1 and 2. Therefore, the sliding contact surfaces S ₁ and S ₂ are less likely to wear, and the insulating bush 14 can be easily replaced. Therefore, even if loosening occurs in this portion, it can be directly returned to the normal state. .

Further, the main shaft mounting hole 1 of the gun bracket 11
Since the bush 11 is interposed between the main shaft 3 and the main shaft 3, the wear in this portion occurs only in the bush 20 whose wear resistance is at least equal to or less than that of the main shaft 3 and the gun bracket 11. Therefore, the predetermined shape can be maintained by replacing the bush 20.

As described above, when repairing the welding gun,
By simply replacing any of the insulating member 16, the insulating bush 14, and the bush 20 according to the progress of wear, it is possible to return to a new state, and it is possible to reduce the man-hours and costs for repair. . Further, since the welding gun can easily maintain its original performance, it is possible to promote stabilization of welding quality of products and cost reduction.

Next, a second embodiment of the present invention will be described with reference to FIG. In the figure, the same or corresponding parts as those of the first embodiment are designated by the same reference numerals, and detailed description will be omitted.

In the second embodiment, the radial roller bearing 15 used in the first embodiment is changed to a so-called oiles bearing 21 made of oil impregnated metal or the like. This oiles bearing 21 has insulating properties and
The lower yokes 1 and 2 and the main shaft 3 are made of a material having at least equal wear resistance. That is, the oiles bearing 21 has the functions of the bearing 15 and the insulating bush 14 in the first embodiment. Therefore, the function and effect of this embodiment are the same as those of the first embodiment, and the description thereof is omitted here.

[0024]

According to the present invention, the following effects can be obtained. On each sliding contact surface between the pair of yokes and one of the pair of yokes and the gun bracket, an insulating member whose abrasion resistance is at least equal to or less than that of the pair of yokes and the gun bracket is provided, and an actual sliding contact surface is provided. By configuring the insulating members so that they are in contact with each other, wear caused by welding work is positively generated only in the insulating members. Further, the pair of yokes and the gun bracket, which are the main components of the welding gun, do not cause wear and can always maintain the regular shape. Therefore, when looseness occurs in the rotating shaft part, just replace the insulating member,
It can be returned to a state like a new one.

Therefore, the number of man-hours and costs for repair can be reduced, and the effect of repair can be greatly enhanced. Further, the welding gun can easily maintain its original performance, and can stabilize the welding quality of the product and promote cost reduction.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a rotating shaft portion of a welding gun showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a rotating shaft portion of a welding gun showing a second embodiment of the present invention.

FIG. 3 is a side view of the welding gun.

4 is a vertical sectional view taken along the line AA of FIG.

[Explanation of symbols]

 1 Upper yoke 2 Lower yoke 3 Spindle 7 Rotating shaft 11 Gun bracket 15 Bearing 16 Insulation member

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mitsuo Kawamoto 2-10-10 Okano, Nishi-ku, Yokohama-shi, Kanagawa Inoue Manufacturing Co., Ltd.

Claims (1)

[Claims] 1. A pair of yokes rotatably provided on the same main shaft via bearings are sandwiched between gun brackets to form a rotary shaft portion, and one of the pair of yokes and one of the pair of yokes is formed. A resistance welding apparatus, wherein an insulating member having at least equal wear resistance to the pair of yokes and the gun bracket is attached to each sliding contact surface with the gun bracket.