JPH0338031B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and device for axial power feeding of a spot welding gun. By interposing an axial power supply unit with a pair of positive and negative rotating conductors stacked concentrically, the power supply unit can be electrically connected to the spot welding gun without using a flexible conductor. The present invention relates to an axial power feeding method and apparatus for a spot welding gun, characterized in that the spot welding gun functions as both a part and a mechanical rotating part.

(Prior Art) Recently, with the rapid increase in the popularity of industrial robots, the development of spot welding guns with welding transformers, commonly referred to as transformer guns, has been rapidly progressing in the welding field with an emphasis on weight reduction and energy conservation. It has come to be put into practical use.

A conventional spot welding gun with a welding transformer will be explained with reference to FIGS. 1 and 2. A support bracket 2 is fixed to the outer frame of a welding transformer 1, and two gun arms 3 and 4 have a common pivot portion on this support bracket 2. One gun arm 4 is fixed to the main body of the pressurizing syringe 6, and the other gun arm 3 is pivoted to the piston rod 7 of the pressurizing syringe 6 via a link 8.
Opposite electrode chips 9 and 10 are attached to the ends of the two gun arms 3 and 4, and power supply bars 11 and 12 of secondary conductors are bolted to the output terminals 1a and 1b of the welding transformer 1, respectively. Furthermore, a welding gun and a welding transformer are usually connected via U-shaped flexible copper plates 13 and 14 between these power supply bars 11 and 12 and conductive plates 15 and 16 connected to each arm 3 and 4. It is.

In general, spot welding guns with welding transformers operated by industrial robots are preferably lightweight and compact so that they can sufficiently handle high-speed, complex operations.

(Problem to be Solved by the Invention) However, in this type of conventional welding gun, the secondary circuit connecting the welding gun and the welding transformer does not connect the power supply bar, flexible copper plate, etc. to the outside as described above. Therefore, as industrial robots operate more complex and at higher speeds, the effects of fatigue disconnections, heat generation deterioration, and spatter during welding are added to the secondary circuits, causing wear and tear on the secondary circuits. Make it intense. In addition, it requires a large installation space for the secondary circuit, and also causes an increase in impedance, which is said to make it impossible to reduce the power consumption and weight of the welding gun. Furthermore, in the past, when using an industrial robot or manipulator to teach a spot welding gun the appropriate posture and angle for the spot welding point on the workpiece, the gun was often pressurized at an incorrect posture or angle. If a twist is applied to the common axis of the two gun arms when pressurizing the gun, this will cause abnormal wear on the bearing, and as the amount of wear increases, the amount of misalignment between the electrode tips at the tip of the gun arm will increase. The problem was that it gradually became larger and had an adverse effect on the welding results.

(Means for Solving the Problems) Therefore, in order to solve the above problems, the present invention provides the following technical means.

That is, the method of the present invention uses a relative pressure between a pair of positive and negative secondary conductors connected to the secondary output terminals of a welding transformer of a spot welding gun and a pair of electrode tips in order to apply the necessary pressure for welding. An axial feed unit consisting of a pair of positive and negative rotating conductors concentrically and rotationally stacked is interposed between the two gun arms that obtain the movement, and the output terminal of the welding transformer is connected to the rotating conductor of this axial feed unit. constitutes a reciprocating circuit for supplying current between the electrode chips,
an electrical connection between the secondary conductor and the gun arm;
To provide a shaft power feeding method for a spot welding gun, characterized in that a mechanical rotating part of a gun arm that needs to move for electrode pressurization also serves as a mechanical rotating part.

In addition, in order to carry out the method of the invention, two gun arms that perform the mechanical movement necessary to apply electrode pressure between a pair of electrode chips, and output terminals of these gun arms and the secondary coil of a welding transformer are provided. An axial power supply unit is interposed between the pair of connected secondary conductors, which serves as an electrode connection part between the secondary conductor and the gun arm, and a mechanical rotation part for the gun arm necessary for pressurizing the gun. In the spot welding gun, the power supply unit is insulated and concentrically and rotatably fitted onto a power supply shaft in which the gun arm and the secondary conductor are pivotally supported on a common support bracket. one gun arm is fixed to the outer periphery of the pivot shaft, and the other gun arm is fixed to the outer circumferential surface of the bushing, and each end of the shaft and the power feeding bush is fixed to the outer periphery of the pivot shaft. The axial holes of the secondary conductor are arranged perpendicularly to the center line, and each end thereof is substantially sealed from the outside by a casing, and each end of the secondary conductor is arranged in a position perpendicular to the center line. To provide an axial power supply device for a spot welding gun, in which a plurality of divided contactors are arranged in a ring shape and are pressurized and brought into close contact with a secondary conductor and a secondary conductor, respectively.

(Function) In the present invention, the welding current can be effectively supplied from the common axis of the two gun arms in the spot welding gun, so in particular, by abolishing the external power supply mechanism of the spot welding gun with the welding transformer, it is possible to substantially reduce the welding current. It is possible to significantly shorten the secondary circuit of the welding gun, make the welding gun lighter and more compact, and save power by reducing impedance.

Furthermore, wear of the pivot portion of the gun arm of the welding gun can be reduced, and the amount of misalignment between the electrode tips can be reduced. Furthermore, by performing the contact power supply in a completely sealed room, it is possible to effectively prevent foreign matter from entering between the sliding power supply surfaces from the outside.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. In the figure, parts having the same structure and function as a conventional spot welding gun with a welding transformer are designated by the same reference numerals and detailed descriptions are omitted.

3 and 4, this embodiment shows an example in which an axial power feeding unit for carrying out the method of the present invention is used in a spot welding gun equipped with a welding transformer.

G indicates an X-type spot welding gun, which faces the gun arm 4 fixed to the main body side of the pressure cylinder 6 and the tip of the gun arm 3 pivoted to the piston rod 7 of the pressure cylinder 6 via a link 8. A pair of electrode chips 9 and 10 are respectively attached, and these two gun arms 3 and 4 are rotatably supported by a common pivot 5 on a support bracket 2 supported on the front surface of the welding transformer 1. . As will be described later, this pivot portion 5 is constituted by an axial power feeding unit 17 having a pair of positive and negative rotating conductors that are not concentrically superimposed.

In Figures 5 and 6, the shaft power supply unit 1
The specific structure of No. 7 has a power supply shaft 18 constituting one rotating conductor that passes through the two gun arms 3 and 4 in common, and the outer circumferential surface of this power supply shaft 18 is located on a protrusion 19 from one side. An insulating material 20 is fitted over the insulating material, and a power supply bushing 21 constituting the other rotating conductor is fitted onto this insulating material. One end 3a of the bifurcated gun arm 3 is fixed to the outer peripheral surface of the power supply bushing with a bolt 42.
Again, one end 3b is fixed to the outer peripheral surface of the power supply shaft 18 via a bearing 22 made of an insulating material. The other gun arm 4 is inserted between the forks and is firmly fixed to the outer peripheral surface of the direct power supply shaft 18 by bolts 43. Therefore, these two gun arms 3 and 4 rotate relative to each other about the same pivot 5, so that a pressurizing action can be applied between the electrode tips 9 and 10.

In this case, one gun arm 3 and support bracket 2 are fitted with insulating bearings 22 and 40 into which the power supply shaft 18 is rotatably inserted, and the other gun arm 4 is fixedly integrated with the power supply shaft 18. The span of the bearings 40 and 41 (distance between shaft supports) is increased to reduce friction caused by twisting of the bearings that occurs when the gun arm is pressurized, thereby reducing the amount of misalignment between the electrode tips. The lifespan of the pivot can be improved.

At the ends where the feed shaft 18 and the feed bush 21 overlap each other, feed bars 23 and 24 forming a pair of positive and negative secondary conductors connected to the output terminals of the welding transformer are inserted from the direction intersecting the axis center line, respectively. These two power supply bars 23 and 24 are insulated and fixed between three insulating materials 25 in a superposed state. 7th
In the figures and FIG. 8, one power feed bar 23 has a shaft hole 26 facing the end of the power feed bush 21, and the other power feed bar 24 has a shaft hole 27 facing the end of the power feed shaft 18. It is set up. Around the shaft hole 26 of one power supply bar 23,
Multiple spring insertion holes 2 radially from the center of the shaft hole
8 is drilled. 31 is a bolt hole.

Numerals 46 and 47 are bolt holes for bolting the power supply bars 23 and 24 to the output terminals 1a and 1b of the welding transformer 1, respectively.

A contactor 29 divided into a plurality of parts is arranged in a ring shape along the inner diameter of the shaft hole 27 of the power supply bar 24 on the distal end surface of the power supply shaft 18, and is pressed by a pressing means to be described later. Another contactor 30 is pressed from the shaft hole 26 of the power supply bar 23 in the same way as described above, and the outer peripheral surface of each contactor 29, 30 is pressed against the shaft hole 26, 27 of each power supply bar 23, 24. It is electrically connected to the inner surface of the body under pressure. The contact surfaces of each contactor 29, 30, power supply shaft 18, and power supply bush 21 are engaged by a "R surface" or a "spherical surface", and are prevented from moving when pressurizing the welding gun arms 3, 4 or from lateral vibration. The structure is such that it can respond with sufficient contact. Springs 32 and 33 are used as resilient members in the pressing means, and one spring 32 is connected to the power supply bar 2.
The contactor 29 is pressed against the front end surface of the power supply bush 21 by the spring force acting on the pressure ring 34 inserted through each spring insertion hole 28 of 4 and located in the shaft hole of the power supply bar 23 to the right. Tapered pressure surfaces that press the wedge surfaces are formed on opposing surfaces of the contactor 29 and the pressure ring 34, respectively. When the pressurizing surface of the pressurizing ring 34 presses the pressurizing surface of the contactor 29, component forces of the pressing force acting on the wedge surface act in two directions, and the contactor 29 is applied to the power supply bush 21 and the power supply bar 23. Pressurize and bring into close contact.

Similarly, the other spring 33 is inserted into the shaft hole 27 of the power supply bar 24 , and presses the coitactor 30 through the pressure ring 35 into the shaft hole 27 of the power supply bar 23 .
The tip end surface of the power supply shaft 18 inserted into the power supply bar 2
4 into the shaft hole 27. These springs 32, 33 are housed in a casing 37 which is fastened to the support bracket 2 etc. by inserting common bolts 36, 36 into the pair of power supply bars 23, 24.

Thus, the contactor power supply section is connected to the power supply bar 23,
24 and is completely sealed by the casing 37, it is possible to effectively prevent foreign matter from entering the contactor power supply section from the outside.

In this practical example, an elastic member such as a spring is used as the pressing means, but the essence of the present invention is not limited to this. For example, as shown in FIG. The action of the cylinder piston 39 causes the spring 3 to
If the pressing force of 2 and 33 can be controlled, for example, by interlocking the fluid pressure of the pressing means when the pressurizing cylinder 6 is operated, contact power can be supplied in a reliable contact state when pressurizing and energizing. .

The operation of the present invention will be explained using the above configuration. The spot welding gun with the welding transformer is operated by reproducing according to the position data stored by the industrial robot, and performs the determined welding work one after another.

Thus, during welding, when the gun arms 3 and 4 are rotated about the common pivot portion 5 by the pressurizing cylinder 6, the power supply shaft 18 and the power supply bush 21 fixed to the gun arms 3 and 4, respectively, are connected to each contactor 29. , 30, and rotate relative to each other about the same axis X--X. In this case, both sides of the power feed shaft 18 are rotatably supported by bearings 40 and 41 of the support bracket 2, and one gun arm 3 is supported by a power feed bush 21 at one end 3a of the bifurcation, and a bearing 22 at the other end 3b. The tip of each arm rotates around the outer periphery of a power supply shaft 18 that is inserted through the electrode tips 9 and 10, so that the pressurizing force necessary for welding is applied to the object to be welded (not shown) sandwiched between the electrode chips 9 and 10. Next, when a welding current is applied, the welding current flows from the output terminal 1a of the welding transformer 1 to the power supply bar 24, and passes through the contactor 30 to the power supply shaft 18. The current flowing through the power supply shaft passes through one gun arm 4 and reaches the electrode tip 10, passes through the object to be welded to the other electrode chip 9, passes through the gun arm 3, and reaches the power supply bush 21. The current flowing through the power supply bush 21 passes through the contactor 29, the power supply bar 23, and returns to the output terminal 1b of the welding transformer.

In this way, contact power supply can be obtained at the pivot portions 5 of the gun arms 3 and 4 of the welding gun in accordance with the movement of the gun arms.

Incidentally, when replacing the shaft power supply unit 17, it can be easily done by removing the bolts 36, 42, and 43.

(Effects of the Invention) As described above, the method of the present invention is achieved by interposing a pair of positive and negative axial power supply units stacked concentrically between the gun arm of the spot welding gun and the secondary side of the welding transformer. By making the power supply unit serve as both the electrical connection part to the spot welding gun and the mechanical rotation part, it is possible to eliminate the complicated and expensive secondary circuit that has many parts and requires a large installation space. is no longer necessary, the impedance of the secondary circuit can be significantly reduced, and power savings can be achieved. Furthermore, according to the axial power feeding device of the present invention, it is possible to reduce the size and weight by unitizing the structure, and the axial power feeding unit can be easily replaced, and the contact power feeding part of this unit is completely sealed. Since it is covered in a closed state, it can be sufficiently protected not only from external impacts but also from foreign objects such as fine dust and spatter. In addition, by making it possible to design the structure of the pivot part to reduce wear caused by twisting of the welding gun's bearing, the amount of misalignment between the electrode chips can be reduced, increasing the life of the welding gun's pivot part. be able to.

In addition, the vibration noise caused by the knocking phenomenon of the secondary cable, which conventionally occurs when the welding gun is energized, completely disappears, and it is also possible to obtain a silent effect when energizing. It is fully capable of handling complex operations, and has many remarkable effects, including improved operability and durability.

[Brief explanation of drawings]

FIG. 1 is a front view showing the structure of a secondary circuit installed in a conventional spot welding gun with a welding transformer, and FIG. 2 is a bottom view of FIG. 1. FIG. 3 is a front view of an embodiment in which an axial power feeding unit for carrying out the method of the present invention is used in a spot welding gun equipped with a welding transformer. FIG. 4 is a bottom view of FIG. 3. Figure 5 is Figure 4A
-A line arrow view. FIG. 6 is an enlarged view including a cross section of the axial power feeding unit of the present invention. FIG. 7 and FIG. 8 are front views showing a pair of positive and negative power supply bars (secondary conductors), respectively. FIG. 9 is a sectional view of a main part showing another embodiment of the pressing means. FIG. 10 is a view taken along the line BB in FIG. 6. [Explanation of symbols], 1... Welding transformer, 2...
Support bracket, 3, 4...Gun arm, 17...
... Axial power feeding unit, 18... Power feeding axis (rotating conductor), 20... Insulating material, 21... Power feeding bush (rotating conductor), 23, 24... Power feeding bar (secondary conductor), 29, 30... Contactor , 32, 33...
...pressing means, G...spot welding gun.

Claims (1)

[Claims] 1. A pair of positive and negative secondary conductors connected to the secondary output terminals of a welding transformer of a spot welding gun and a pair of electrode tips to provide a relative pressure necessary for welding. With two gun arms that obtain movement,
An axial feed unit consisting of a pair of positive and negative rotating conductors stacked concentrically and rotationally is provided, and current is supplied to the rotating conductor of the axial feed unit from the output terminal of the welding transformer to the electrode tip. For a spot welding gun, the electric connection part between the secondary conductor and the gun arm, which forms a reciprocating circuit for the purpose of the spot welding gun, also serves as a mechanical rotation part of the gun arm that needs to move to pressurize the electrode. Axial power feeding method. 2 Two gun arms that perform the mechanical movement necessary to apply electrode pressure between a pair of electrode chips, and a pair of secondary conductors connected to these gun arms and the output terminal of the secondary coil of a welding transformer. The spot welding gun is provided with an axial power supply unit interposed between the secondary conductor and the gun arm, which serves both as an electrical connection part to the gun arm and as a mechanical rotation part to the gun arm necessary for electrode pressurization. The unit has a power supply shaft in which the gun arm and the secondary conductor are pivotally supported on a common support bracket, and a power supply bushing concentrically and rotatably fitted onto the shaft in an insulated state. , one gun arm is fixed to the outer periphery of the pivot, and the other gun arm is fixed to the outer periphery of the bush, and each end face of the pivot and the power feed bush is located at a position that intersects at right angles to the center line of the pivot. Each shaft hole and each end face are substantially sealed from the outside by a casing, and each end face side and each secondary conductor side are in this sealed interior. This is an axial power supply device for a spot welding gun, in which a plurality of divided contactors are arranged in a ring shape, each of which is pressurized and brought into close contact with each other by receiving a pressing force.