JPH0794073B2 - Resistance welding equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a resistance welding apparatus, and more specifically to an apparatus for performing resistance welding by supplying a welding current to a resistance welding gun attached to a spot welding robot or the like. In particular, in the type of resistance welding gun in which the gun body swings,
When supplying a current when joining the workpieces, the power receiving terminal on the gun body side is clamped by the clamp means provided in the power feeding device, while after the workpieces are joined, the power receiving terminal is released from the clamp means. The present invention relates to a resistance welding apparatus capable of ensuring a smooth welding process without hindering the swinging operation of the resistance welding gun.

BACKGROUND OF THE INVENTION For example, when assembling an automobile body, it is common to join thin plate materials as works by spot welding. In recent years, such spot welding process is performed exclusively by a robot. By the way, a resistance welding gun is equipped on the wrist of such a spot welding robot, and this resistance welding gun clamps a work with electrodes attached to the tips of a pair of openable and closable gun arms, and presses the space between the electrodes. The work is joined by applying an electric current to. There are various types of resistance welding guns of this type. Among them, there is a type of resistance welding gun in which the gun body swings so as to shake its head as the gun arm opens and closes. The resistance welding gun disclosed in Japanese Utility Model Laid-Open No. 57-49079 filed by the present applicant corresponds to this type of resistance welding gun, which is shown in FIGS. 1 and 2.

In the figure, reference numeral 2 indicates a resistance welding gun. First, a bracket 8 is swingably supported via a support shaft 10 on a support arm 6 fixed to a machine base 4 extending from a robot arm or the like. This bracket 8 has a fixed gun arm
12 is fixed, and an electrode 14 is attached to the tip of the fixed gun arm 12.
Is installed. In addition, the bracket 8 has a conductive member 15
The one end side of the conductive member 15 is connected to the fixed gun arm 12, and the connecting portion 15a provided on the other end side protrudes outward from the bracket 8 and between the connecting portion 15a and the supporting arm 6. A compression spring 17 is engaged with this. The operation of the compression spring 17 will be described later.

On the other hand, a movable gun arm 16 having a shape that bends corresponding to the fixed gun arm 12 is provided, and the movable gun arm 16 is substantially rotatable. The movable gun arm
An electrode 18 is attached to the tip of 16 and a connecting lever 20 is attached to its tail end, and the connecting lever 20 is connected to a cylinder 22 that drives the movable gun arm 16 to open and close. That is, the cylinder 22 is fixed to the bracket 8, and the tip end portion of the piston rod 26 extending from the piston 24 of the cylinder 22 is connected to the connecting lever 20 via the pin 28. Further, a pin 30 is attached to the pin 28 at a predetermined distance from the connecting lever 20, and the pins 28 and 30 are both engaged with a curved cam groove 32 formed in the bracket 8.

Therefore, in FIG. 1, when the cylinder 22 is urged to displace the piston 24 in the direction of arrow D, the movable gun arm is moved.
In 16, the pins 28 and 30 provided on the connecting lever 20 are displaced along the cam groove 32, and the electrode 18 rotates in the direction of arrow B. On the other hand, the elastic force of the compression spring 17 acts in the direction of arrow A, whereby the entire bracket 8 rotates about the support shaft 10 in the direction of arrow A so that the fixed gun arm 12 approaches the work W. Is displaced to. Finally, as shown in FIG. 2, the work W has a fixed gun arm 12 and a movable gun arm 16.
Sandwiched between.

Here, a step portion is formed in the central portion of the piston rod 26, and substantially, as shown in FIGS. 1 and 2, a cam surface 34 having a curved surface is formed in the step portion. ing. Therefore, referring to FIG. 2, the piston of the cylinder 22
When 24 is displaced in the direction of arrow C, the movable gun arm 16 is displaced in the opening direction and separated from the work W, contrary to the above. Then, the cam surface 34 of the piston rod 26 contacts the tip portion 6a of the support arm 6. Further, since the piston 24 is allowed to displace in the arrow C direction, the cam surface 34 is eventually
Since the abutting position of the support arm 6 with respect to the tip end portion 6a is displaced along, the bracket 8 as a whole is compressed by the compression spring.
Rotate in the direction of arrow B against the elastic force of 17. As a result, the fixed gun arm 12 fixed to the bracket 8
Moves away from the work W and the entire resistance welding gun 2 rotates in the same direction (see FIG. 1).

As described above, since the gun main body swings, the gun main body can be retracted from the work W, and when the work W is moved to change the spot hitting position, for example, when the work W is moved in the direction orthogonal to the drawing. Avoided from the inconvenience of interference.

In this case, in order to supply a current to the resistance welding gun 2, the ounces 36a and 36b as power feeding cables connected from the power source are attached to the connecting portion 15a of the conductive member 15 mounted on the bracket 8. In this case, the terminal of the ounce 36a is connected to the fixed gun arm 12 through the conductive member 15, while the terminal of the ounce 36b is connected to the movable gun arm 16 by the conductor 38 and the ounce 40.
Connected through.

Therefore, during the welding operation, when the resistance welding gun 2 swings as described above, the ounces 36a and 36b integrally attached to the resistance welding gun 2 are bent ( (See FIG. 1).

By the way, in recent years, a thin plate material used for an automobile body is often treated with a rust preventive treatment, for example, a zinc-treated steel plate or the like. It is big. For this reason, recently, a power supply cable has a large cross-sectional area in order to increase its current capacity. Therefore, it is difficult for the power supply cable to flex freely, and there is a disadvantage that the swinging operation performed by the resistance welding gun 2 for preventing the interference with the work W is obstructed.

[Object of the Invention] The present invention has been made to overcome the above-mentioned inconvenience, and in connecting the power receiving terminal provided on the resistance welding gun body to the power feeding device side, the actuator is used only when welding the work. A swinging operation of the resistance welding gun is configured by sandwiching the power receiving terminal by the displacing clamp means to electrically connect the power receiving terminal and disconnecting the power receiving terminal and the power feeding terminal after welding is completed. It is an object of the present invention to provide a resistance welding device capable of smoothly performing a welding process and capable of supplying a large current required for welding without any trouble.

[Means for Achieving the Object] In order to achieve the above-mentioned object, the present invention has a fixed gun arm having one electrode at the tip end and fixed to a bracket, and the other electrode at the tip end. A welding gun having a movable gun arm capable of tilting with respect to a fixed gun arm is provided, and the movable gun arm is tilted relative to the fixed gun arm to sandwich a work by the one electrode and the other electrode to supply a welding current. In the resistance welding apparatus for performing resistance welding, a first actuator for tilting the movable gun arm, a holder fixed to the fixed gun arm side, a power receiving terminal provided at one end of the holder, and the welding A power feeding portion provided at a predetermined distance from the gun side, and the power feeding portion is provided with the holder as the movable gun arm tilts. Clamping means including a set of brackets defining a space for receiving a physically rotating power receiving terminal, and the pair of brackets relatively approach each other in a direction orthogonal to a tilting direction of the power receiving terminal. When the second actuator to be separated from the movable gun arm is tilted and the electrode and the electrode on the fixed gun arm side hold the work,
A power feeding terminal that feeds a welding current by contacting the power receiving terminal that has reached the space of the pair of brackets with the urging action of the second actuator.

[Operation] By biasing the first actuator, the movable gun arm is tilted or rotated so as to relatively approach the fixed gun arm side. As a result, the work is held between the electrode on the movable gun arm side and the electrode on the fixed gun arm side.

On the other hand, the tilting of the movable gun arm causes the holder and the power receiving terminal to move integrally to the power feeding portion side, and the power receiving terminal faces the power feeding terminal of the power feeding portion at the work clamping position by the electrode of the movable gun arm and the electrode of the fixed gun arm. Leading to. Here, the second actuator is energized, the power supply terminal contacts the power reception terminal, and the resistance welding current is supplied to the electrode.

After the welding is completed, the second actuator is urged again to separate the power supply terminal and the power receiving terminal from each other, and then the first actuator is urged in the opposite direction to move the movable gun arm relative to the fixed gun arm. Away from.

[Embodiment] Next, a resistance welding apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. In this embodiment, the same reference numerals as those used in FIGS. 1 and 2 denote the same components, and detailed description thereof will be omitted.

3 and 4, reference numeral 50 indicates a resistance welding device according to the present invention. The resistance welding device 50 includes a power receiving portion 52 provided on the resistance welding gun 2 side and a clamp means 54 on the power feeding portion side that sandwiches the power receiving portion 52 and supplies a current from a power source side (not shown).

Therefore, the clamp means 54 will be described. First, the fixed side holding member 56 is fixed to the bracket 55 by the bolt 58. An end portion of a cylinder 60 is connected to a lower end side of the fixed side holding member 56 by a hinge pin 61.
The spin rod 62 is connected to a lower end portion of a movable side holding member 66 which is swingably supported by the bracket 55 via a pin 64. The fixed side holding member 56 and the movable side holding member 66 are separated from each other by a predetermined distance, that is, a space is defined, and electrodes 68a and 68b are fixed to inner surfaces of the two members facing each other. As shown in FIG. 4, the other ends of the ounces 70a, 70b whose one ends are connected to secondary power supply terminals such as a welding transformer (not shown) are attached to the ends extending outward from the respective 68, 68b. Has been done. In this case, if protrusions 72a and 72b that bulge in a hemispherical shape are formed on the opposing surfaces of the electrodes 68a and 68b, a good connection state with the power receiving unit 52 can be obtained, as described later.

On the other hand, the power receiving portion 52 is formed by fixing two conductive plates 74a and 74b as power receiving terminals connected to the connecting portion 15a of the conductive member 15 with a holder 76 via an insulating member. The conductive plate 74a
Is connected to the fixed gun arm 12 side via the conductive member 15,
The conductive plate 74b is connected to the movable gun arm 16 side through the conductor 38 and the ounce 40 (see FIGS. 5 and 6).

The resistance welding apparatus according to the present invention is basically configured as described above, and its operation will be described next.

First, as shown in FIG. 5, at the start of spot welding, conductive plates 74a and 74b as power receiving terminals of the resistance welding gun 2 are used.
Are separated from the power supply device 50 in advance. So the cylinder
By urging 22 to displace the piston 24 in the direction of arrow D, the cam surface 34 of the piston rod 26, which was in contact with the tip portion 6a of the support arm 6, is separated, so that the elastic force of the compression spring 17 The entire bracket 8 rotates about the spindle 10 in the direction of arrow A, and the fixed gun arm 12 approaches the work W side as the bracket 8 rotates. On the other hand, since the pins 28 and 30 of the connecting lever 20 connected to the piston rod 26 are displaced along the cam groove 32 of the bracket 8 with the displacement of the piston 24, the movable gun arm 16 integral with the connecting lever 20 is a work piece. It is displaced toward the W side in the closing direction. Finally, the work W is pinched by the electrodes 14 and 18 attached to the tips of the fixed gun arm 12 and the movable gun arm 16, respectively. At this time, as easily understood from FIG. 6, the conductive plates 74a and 74b are the fixed side holding members that constitute the power feeding device 50.
56 and electrodes 68a, 6 disposed on the movable side holding member 66, respectively.
It will be located between 8b. Ie electrode 14 and electrode
When 18 and the work are completely sandwiched, the two conductive plates 74a and 74b as power receiving terminals face the electrodes 68a and 68b as power feeding terminals for the first time.

Therefore, in FIG. 3 and FIG. 4, when the ring 60 is biased and the piston rod 62 of this cylinder 60 is moved forward in the direction of the arrow, the movable side holding member 66 connected to this piston rod 62 is pinned. Fixed side clamping member 56 with 64 as a fulcrum
And the electrodes 68a, 68b between them rotate to the conductive plates 74a, 74b.
To pinch. At this time, if a current is supplied from a welding transformer (not shown) through the ounces 70a, 70b connected to the electrodes 68a, 68b, the electrodes 14 and 18 provided on the fixed gun arm 12 and the movable gun arm 16 respectively sandwich the electrodes. An electric current flows through the work W to be welded, and the work W is welded by the Joule heat generated when the current is passed.

Therefore, after the work W is joined, the supply of the electric current is stopped, and the piston of the cylinder 22 provided in the resistance welding gun 2 is stopped.
24 is displaced in the direction of arrow C. Then, at this time, in the resistance welding apparatus 50, the piston rod 62 of the cylinder 60 is retracted to rotate the movable side holding member 66 away from the fixed side holding member 56, and the conductive plates 74a and 74b are moved. The clamp state for will be released.

Therefore, when the piston 24 is displaced in the direction of arrow C, the cam surface 34 formed on the piston rod 26 comes into contact with the tip portion 6a of the support arm 6. At this time, the movable gun arm 16 is rotated to a position spaced apart from the work W by a predetermined angle, and together with this, the action of the cam surface 34 causes the entire bracket 8 to rotate in the arrow B direction. Is displaced in the direction away from. In this case, since the conductive plates 74a and 74b are completely free, the turning operation of the resistance welding gun 2 is not hindered. Therefore, it is possible to perform spot welding at the next hitting point position without any interference without interfering with the work W.

[Effects of the Invention] As described above, according to the present invention, when connecting the power receiving terminal of the resistance welding gun in which the gun body swings at the time of joining the work and the power supply device side, the work is completely narrowed by the gun body. Only at the held position, the power receiving terminal faces the power feeding terminal, and both terminals are joined under the urging action of the actuator to start power feeding. Therefore, in the prior art, in advance,
If the welding gun holds the work while power is being supplied,
Although a large current flows all at once, sparks or the like are generated, resulting in defective welding, but the present invention can avoid such inconvenience. Further, since the current-carrying current is carried by sandwiching the power-receiving terminal by the clamping means driven by the actuator arranged on the power-feeding side, the power-receiving terminal is in the unclamped state except when welding the work piece. Also, since the tilting movement of the gun body when the fixed gun arm rotates is completely free, the movement is not hindered. That is, before power feeding to the power receiving terminal, the power receiving terminal can perform a tilting operation irrespective of the power feeding side. Therefore, in the prior art, the tilting welding gun is restricted in its operation by the power supply cable (ounce) on the power supply side. However, according to the present invention, the restriction is avoided. In addition, the power supply cable for supplying a large current can be made large without considering the size of its flexibility, so that there is an advantage in that it can be escaped from design restrictions. As a result, a sufficient welding current can be supplied, whereby a product having a desired welding strength can be obtained.

[Brief description of drawings]

1 and 2 are configuration explanatory views of a resistance welding gun in which the resistance welding apparatus according to the present invention is incorporated, FIG. 3 is a side view of the resistance welding apparatus according to the present invention, and FIG. 4 is a resistance according to the present invention. FIG. 5 and FIG. 6 are perspective views of the welding apparatus, and are diagrams for explaining a method of supplying power to the resistance welding gun in relation to the resistance welding apparatus according to the present invention. 2 ... Resistance welding gun, 6 ... Support arm 8 ... Bracket, 12 ... Fixed gun arm 14 ... Electrode, 16 ... Movable gun arm 17 ... Compression spring, 18 ... Electrode 20 ... Connection lever, 22 ... … Cylinder 24 …… Piston, 26 …… Piston rod 28,30 …… Pin, 32 …… Cam groove 34 …… Cam surface, 50 …… Resistance welding device 56 …… Fixed side clamping member, 60 …… Cylinder 66… ... Moveable side clamping member

Front Page Continuation (72) Inventor Hisashi Noro 1-10-1 Shin-Sayama, Sayama-shi, Saitama Honda Engineering Co., Ltd. (72) Inventor Naoki Katsura 1-10-1 Shin-Sayama, Saiyama City, Saitama Prefecture Honda Engineering Co., Ltd. In-house (56) References JP-A-56-119674 (JP, A) Actual development: S57-49079 (JP, U)

Claims (1)

[Claims] 1. A welding gun having a fixed gun arm having one electrode at its tip and fixed to a bracket, and a movable gun arm having the other electrode at its tip and tiltable with respect to said fixed gun arm, In a resistance welding apparatus for performing resistance welding by tilting the movable gun arm relative to the fixed gun arm, sandwiching a work by the one electrode and the other electrode, and supplying a welding current, the movable gun arm is tilted. And a holder fixed to the fixed gun arm side, a power receiving terminal provided at one end of the holder, and a power feeding section provided at a predetermined distance from the welding gun side. A pair of the power feeding section defining a space section for receiving a power receiving terminal that rotates integrally with the holder in accordance with the tilting movement of the movable gun arm. Clamping means including a bracket, a second actuator that moves the pair of brackets toward and away from each other in a direction orthogonal to the tilting direction of the power receiving terminal, the movable gun arm tilts, and its electrode and a fixed gun arm. When the work is clamped by the side electrode,
A resistance welding apparatus, comprising: a power supply terminal that supplies a welding current by contacting the power reception terminal that has reached the space of the pair of brackets under the urging action of the second actuator.