JP2562099B2 - Resistance welding gun - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a resistance welding gun,
More specifically, when a welding transformer is held in one of the pair of resistance welding gun arms and a power receiving terminal is provided in the other gun arm, the one and the other gun arms are relatively rotated. The present invention relates to a resistance welding gun capable of engaging and disengaging an output terminal extending from a welding transformer with the power receiving terminal to supply and cut off a resistance welding current.

[0002]

2. Description of the Related Art The present applicant has already filed Japanese Patent Application Laid-Open No. 2-21198.
No. 4 proposes a resistance welding device. This resistance welding device significantly reduces the contact resistance when supplying a resistance welding current, prevents power loss, and further enables efficient supply of a direct current to a set of welding electrodes. It is a thing. In such a resistance welding device, a transformer and a rectifier connected to the secondary coil side of the transformer,
A pair of openable and closable gun arms for attaching the respective welding electrodes facing each other are provided, and the rectifier is directly engaged with one of the gun arms.

In this case, since the output terminal extending from the secondary coil is directly connected to the rectifier, there is no voltage drop between the output terminal and the rectifier, but from the transformer to the other gun arm. Since a so-called ounce copper plate, in which a large number of copper plates are laminated, is used for power supply to, there is a concern that the ounce copper plate itself may be worn.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to eliminate the above-mentioned concerns. In particular, a welding transformer is disposed on one resistance welding gun arm and one and the other gun arms are arranged. When rotating relatively, the output terminal of the secondary coil extending from the welding transformer makes electrical contact with the power receiving member, thereby avoiding a voltage drop at the connection site without using an ounce copper plate. Then
It is intended to provide an efficient resistance welding gun.

[0005]

To achieve the above object, the present invention is a resistance welding gun having a pair of gun arms for freely opening and closing an electrode tip, wherein one gun arm extends from a welding transformer. One output terminal is engaged with the rectifier, the other gun arm is provided with a power receiving terminal, and the other output terminal of the welding transformer is engaged with the power receiving terminal under the relative rotational action of the one gun arm and the other gun arm. It is characterized by being detachable.

[0006]

The alternating current taken out from the secondary side of the welding transformer is converted into the direct current through the rectifier and is then fed to the electrode tip for welding the work through the gun arm.
That is, the output terminal extending from the welding transformer is engaged with the power receiving member fixed to the other gun arm of the pair of gun arms, and the welding current is supplied.

According to the present invention, since the output terminal directly engages with the power receiving terminal and the connecting ounce copper plate is not used, there is no concern about the voltage drop due to the presence of the ounce copper plate and the wear of the ounce copper plate. Moreover, the resistance welding is efficiently performed.

[0008]

The preferred embodiments of the resistance welding gun according to the present invention will now be described in detail with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates a gun bracket, and the gun bracket 10 is fixed to an arm of a robot (not shown). A shaft member 12 is provided at the tip of the gun bracket 10, and a first gun arm 14 and a second gun arm 16 are pivotally supported by the shaft member 12. In this case, the first gun arm 14 is the fixed side, and the first electrode tip 18 is replaceably fixed to the tip portion of the first gun arm 14, while the second gun arm 16 is the movable side, and the second gun arm 16 is the second side at the tip portion. The electrode tip 20 is fixed so as to be replaceable. A bulging portion 22 is provided at a substantially central portion of the first electrode tip 18 of the first gun arm 14, while a bulging portion 24 is provided at a substantially central portion of the second electrode tip 20 of the second gun arm 16. ing. These bulges 2
2 and the bulging portion 24 respectively have holes formed in the shaft member 1
By inserting 2, the gun bracket 10 and the second gun arm 16 are pivotally supported with respect to the first gun arm 14. In the figure, reference numeral 25 indicates an insulating member for insulating the shaft member 12 from the gun bracket 10 and the like.

A first rod 26 further extends on the side of the first gun arm 14 opposite to the first electrode tip 18, and a second electrode is provided at the tip of the first rod 26 with respect to the first electrode tip 18. A first air cylinder 28 is provided as an actuator for moving the chips 20 toward and away from each other. The cylinder rod 30 extending from the first air cylinder 28 is connected to one end of the connecting member 34. The other end of the connecting member 34 is connected to a second rod 32 extending to the opposite side of the second gun arm 16 from the second electrode tip 20. The cylinder rod 3
0, shaft members 36 and 38 are used for connecting the second rod 32 and the connecting member 34.

By the way, in the present invention, the transformer 40 for resistance welding is provided inside the space defined by the first rod 26 and the second rod 32. That is, the transformer 4
At 0, the output terminals 44a and 44b are extended with respect to the rectifying device 42 provided in the bulging portion 24 of the second gun arm 16 to form the diodes 46a and 4b which constitute the rectifying device 42.
6b is configured to be held via the connecting member 48 and pressing plates 50a and 50b accommodating disc springs (not shown). A detailed description of the structure of the rectifying device 42 is disclosed in the resistance welding device of JP-A-2-211984.

On the other hand, the center tap 60, which once extends horizontally from the transformer 40, rises vertically upward in FIG. The tip portion of the center tap 60 is above the bulging portion 22 and faces the power receiving member 62 formed on the first gun arm 14. The power receiving member 62 is the bent first member 6 as easily understood from FIGS. 1 and 4.
4 and the second member 66, the first member 64 and the second member 6
6 is supported by a shaft 68. A second air cylinder 72 is provided in a space 70 defined by the bent shape of the first member 64, and a cylinder rod 74 of the second air cylinder 72 is axially attached to one end of the second member 66. Has been done. A terminal 76 is provided at the other end of the second member 66. The first member 64 is also provided with a terminal 78 facing the terminal 76. Therefore, when the second air cylinder 72 is advanced, the cylinder rod 74 rotationally displaces the second member 66 around the shaft 68, and the terminal 7
6 approaches the terminal 78, while the second air cylinder 7
When 2 is retracted, terminal 76 separates from terminal 78.

The resistance welding gun according to the present invention is basically constructed as described above, and its operation will be described below.

When the first air cylinder 28 is driven to retract the cylinder rod 30, the connecting member 34 moves in the direction of arrow A in FIG. 1, and as a result, the second gun arm 16 moves around the shaft member 12. It is rotated in a direction away from the first gun arm 14. Therefore, the second electrode tip 20 is separated from the first electrode tip 18 (direction of arrow D in FIG. 1).

Therefore, a work (not shown) is arranged between the first electrode tip 18 and the second electrode tip 20. In this case, the work is displaced and inserted between the first electrode tip 18 and the second electrode tip 20, and the gun bracket 10 is moved to the work side under the displacement operation of the robot (not shown). It is also possible to dispose the work between the first electrode tip 18 and the second electrode tip 20 as described above.

Next, the first air cylinder 28 is driven to move the cylinder rod 30 forward. As a result, the connecting member 34 moves in the direction of the arrow B, and moves in the second direction around the shaft member 12.
The gun arm 16 rotates toward the first gun arm 14 side, and the electrode tips 18 and 20 come close to each other. This time,
The center tap 60 will enter between the terminals 76 and 78. Then, the second air cylinder 72 is urged to move the cylinder rod 74 forward. As a result, the terminal 76
Is displaced toward the terminal 78, and the tip of the center tap 60 is clamped by the terminals 76 and 78. When the welding current is supplied by the transformer 40, the direct current rectified by the rectifying device 42 is fixed to the tip portions of the first gun arm 14 and the second gun arm 16, respectively, and the first electrode tip 18 and the second electrode tip 20 are fixed. Flow in between,
Direct current resistance welding is achieved by generating Joule heat to the work.

After the welding is completed, the second air cylinder 7
2. The first air cylinder 28 retracts.

In this case, according to the present invention, the transformer 40
A center tap 60 extending from is directly contacted with a power receiving member 62 provided on the first gun arm 14 so as to flow a welding current. That is, no ounce copper plate or the like is required. Therefore, there is an advantage that the welding quality with respect to the work is further improved without causing the voltage drop at the connection portion which has been conventionally caused by using the ounce copper plate.

[0019]

As described above, according to the present invention, when performing DC resistance welding, the output terminal of the secondary coil extending from the transformer is directly contacted with the power receiving member fixed to the gun arm. . Therefore, the voltage drop at the time of welding current feeding at this portion is eliminated, and further, the resistance welding gun can be extremely miniaturized, and since there is no ounce copper plate, this enables efficient welding as a resistance welding gun. The effect of being made is obtained.

[Brief description of drawings]

FIG. 1 is a partially longitudinal front view of a resistance welding gun according to the present invention.

FIG. 2 is a perspective view of a resistance welding gun according to the present invention.

FIG. 3 is a III view of the resistance welding gun according to the present invention in FIG.
3 is a sectional view taken along line III-III.

FIG. 4 is a front view of a power receiving member of the resistance welding gun according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Gun bracket 14 ... 1st gun arm 16 ... 2nd gun arm 18 ... 1st electrode tip 20 ... 2nd electrode tip 28 ... 1st air cylinder 40 ... Transformer 42 ... Rectifier 62 ... Power receiving member 72 ... 2nd air cylinder

Claims (2)

(57) [Claims] 1. A resistance welding gun having a pair of gun arms for opening and closing an electrode tip, wherein one output arm extending from a welding transformer is attached to one gun arm together with a rectifier, and the other power receiving terminal is attached to the gun arm. The resistance welding gun is characterized in that the other output terminal of the welding transformer can be engaged with and disengaged from the power receiving terminal under the relative rotational action of the one gun arm and the other gun arm. 2. The resistance welding gun according to claim 1, wherein the other output terminal of the welding transformer is a center tap.