JPH0292469A - Roll spot welding machine - Google Patents

Abstract

PURPOSE:To execute satisfactory welding even if an electrode is worn out by connecting one electrode to a piston rod of a cylinder, and connecting the other electrode to the cylinder body, and also, connecting it to a sliding body which is fitted so as to be freely slidable to a guide member attached to a movable arm. CONSTITUTION:When a pair of electrodes 2, 3 move to a position where an object to be welded can be inserted and held, a cylinder 18 operates and elongates a piston rod 18a, the electrode 2 abuts on the object to be welded, and moves to the electrode 3. In this case, back pressure is generated and the electrode 3 connected to a pressure cylinder 18 moves to the upper part, and the object to be welded is inserted and held by a pair of electrodes 2, 3. This back pressure works until electrode pressing force of the electrode 2, 3 becomes equal. The electrodes 2, 3 are guided along a weld line of the object to be welded by a robot arm (movable arm) 37, while executing an electric conduction, and execute roll spot welding. In such a way, even if a pair of electrodes are worn out and an electrode pressure point is deflected, satisfactory roll spot welding can be executed without damaging the object to be welded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention involves sandwiching a welding line of a workpiece with a pair of electrodes, and performing roll spot welding while applying current and pressure along the welding line of the workpiece. This invention relates to an improvement of a roll spot welding machine that performs.

(Prior Art) A conventionally used roll spot welding machine will be explained based on FIGS. 4 and 5.

In the figure, 1 is the roll spot welding machine main body, and 2.3 is a pair of electrodes provided on the roll spot welding machine main body 1. 4 is an electrode head, and 5 is a power supply shaft. The power supply shaft 5 is rotatably fitted into the electrode rod 4, and one electrode 2 of a pair of electrodes 2.3 is attached to the tip thereof. A power supply block 6 for supplying welding current is connected to the power supply shaft 5, and a welding transformer (not shown) is connected to the power supply block 6 via a secondary cape.

7 is an electrode head, and 8 is a power supply shaft. The power supply shaft 8 is rotatably fitted into the electrode rod 7, and the other electrode 3 of the pair of electrodes 2 and 3 is attached to the tip thereof. A power supply block 9 for supplying welding current is connected to the power supply shaft 8, and a welding transformer (not shown) is connected to the power supply block 9 via a secondary cable. to and tt are brackets arranged on both sides of the electrode rad 4.7, and 12.13 are guide rails arranged on both sides of the electrode rad 4. Guide rail 12.13
is mounted on a base 14.15 fixed to a bracket 10.11.

Reference numerals 16 and 17 denote bearings (sliding members, hereinafter the same) that are slidably fitted to the guide rails 12 and 13, and the bearings 16 and 17 are fixed to both sides of the electrode pad 4, respectively. As a result, the electrode rad 4 slides up and down the guide rail 12.13 (see FIG. 4).The electrode rad 7 is fixed and supported by the lower end of the bracket 10.11.

18 is a pressurizing cylinder attached to the upper part of the rad 4 to one electrode, and the piston rod 18 of the pressurizing cylinder 18
A knuckle 19 is attached to a. Further, a cylinder mounting plate 20 is fixed to a portion of the pressure cylinder 18 on the piston rod 18a side, and a hole 20a through which the piston rod 18a of the pressure cylinder 18 passes is bored in the center of the cylinder mounting plate 20. has been done.

Further, hinges 21 and 22 are provided on both sides of the hole 20a of the cylinder mounting plate 20, and these hinges 21 and 2
2 and a hinge 23.24 provided at a suitable position on the upper part of the bracket 10.11 are rotatably connected by a hinge pin 25.26. Therefore, the pressure cylinder 18 is rotatably attached to the bracket 10.11.

Reference numeral 27 denotes a link fixed to the electrode rad 4, and a long hole 28 is formed in the side surface of the link 27, which is perpendicular to the moving direction (vertical direction in FIG. 4) so that the rad 4 can be moved to the electrode.

The link 27 has a base end attached to a bracket t by a pin 30.
One side of the link 29, which is rotatably connected to links 31 and 32 provided at appropriate positions of o and tt, is rotatably connected by a pin 33 through an elongated hole 28. Also, link 29
The other side is rotatably connected to the knuckle 18 attached to the piston row and door 18a by a pin 34.

35.3B is a mounting plate fixed to bracket 10.11. As a result, the roll spot welding machine main body l is
It is attached to a movable arm of a robot (not shown), that is, a robot arm 37 via this attachment plate 35.3B.

The roll spot welding machine configured as described above operates as follows.

When the object to be welded (not shown) is positioned at a predetermined position, a pair of electrodes 2 provided on the roll spot welding machine main body l,
3 moves to a position where the robot arm 37 grips the welding start point of the workpiece, and extends the piston rod 18a of the pressurizing cylinder 1B.

When the piston rod 18a of the pressure cylinder 18 expands, the pressure force of the pressure cylinder 18 is applied to the knuckle 19 and the link 2.
9. communicated with the link 27 to move the electrode head 4 along the guide rail 12.13 towards the electrode 7;
The welding start point of the object to be welded is held between a pair of electrodes 2.3 with considerable pressure. When the welding start point of the workpiece is clamped, the pair of electrodes 2 and 3 are energized, and the robot arm 37 is taught to guide the roll spot welding machine body l along the welding line of the workpiece. , guided along the welding line of the workpiece. As a result, the pair of electrodes 2.3 perform roll spot welding along the welding line of the workpiece while rotating due to the electrode pressurizing force on the workpiece and the driving force of the robot arm 37.

In this way, the weld lines of the objects to be welded are roll spot welded, and when welding of all the desired weld lines of the objects to be welded is completed, the pressure cylinder 18 is operated again, and the pressure cylinder 1
The piston rod 18a of No. 8 is shortened.

When the piston rod 18a of the pressurizing cylinder 18 is shortened, the electrode rod 4 moves in a direction away from the electrode head 7, and the pair of electrodes 2.3 release the welding line of the workpiece.

Then, when the pair of electrodes 2 and 3 release the welding line of the workpiece, the robot arm 37 returns the roll spot welding machine main body 1 to its original position, and one cycle of welding is completed.

(Problems to be Solved by the Invention) However, in the above conventional roll spot welding machine, welding is performed by turning the edges.

There is a problem in that the pair of electrodes gradually wears out, and the pressure point of the pair of electrodes gradually deviates from one electrode toward the other. Therefore, if welding continues, only one of the pair of electrodes will come into contact with the workpiece, which may deform the workpiece or
This has caused problems such as damage and welding defects.

In order to prevent damage to the workpiece due to one electrode of a pair of electrodes, the operation of the roll spot welding machine is stopped at regular intervals, and only a value corresponding to the amount of wear of the pair of electrodes is applied. The movement of the robot arm must be corrected, which places an extra burden on the worker and reduces productivity.

In addition, a deviation detector (e.g., actuation transformer, potentiometer, Cds, etc.) that detects the amount of wear on the pair of electrodes was installed, and this deviation detector sequentially detected the amount of wear on the pair of electrodes. It is also possible to calculate the amount of wear and correct the movement of the robot arm, but this also requires a deviation detector and its control device.
There were problems in that not only the production cost was high, but also the control of the entire device was complicated.

The present invention was made with the aim of solving the above-mentioned conventional problems.Even if a pair of electrodes is worn out, if one electrode comes into contact with the workpiece, the other electrode will follow the other electrode. To provide a roll spot welding machine which has a simple structure, is free from welding defects, and has a low manufacturing cost, so as to come into contact with a workpiece to be welded.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a pair of electrodes 2.3.
A roll spot welding machine main body 50 equipped with the above is attached to a movable arm, and a workpiece to be welded is held between the pair of electrodes 2.3, and the workpiece is welded by the movable arm using the pair of electrodes 2.3. In a roll spot welding machine that performs roll spot welding by applying current and applying pressure while guiding along a line, one electrode 2 of the pair of electrodes 2.3 is provided in the roll spot welding machine main body 50. The pair of electrodes 2.3 are connected to the rod 18a.
The other electrode 3 is connected to the main body of the cylinder 18, and the other electrode 3 is connected to a sliding body slidably fitted to a guide member attached to the movable arm.

(Function) Since the configuration is as described above, before welding, the roll spot welding machine main body 50 attached to the movable arm is on standby at its original position.

Once the object to be welded (not shown) is positioned at a predetermined position,
A pair of electrodes 2.3 of the roll spot welding machine main body 50 are
The movable arm moves the object to be welded to a position where it can hold the welding start point.

When the pair of electrodes 2.3 move to a position where they can grip the welding start point of the workpiece, the cylinder 18 is actuated to extend the piston rod 18a of the cylinder 18, and one electrode 2 moves to the welding start point of the workpiece. and moves toward the other electrode 3. At this time, back pressure is generated, and due to this back pressure, the other electrode 3 connected to the pressurizing cylinder 1 moves upward, and the pair of electrodes 2 degrees of this moved other electrode 3 and one electrode 2 This back pressure that holds the welding start point of the workpiece by 3 acts until the electrode application force of one electrode 2 and the electrode application force of the other electrode 3 become equal, so that the weld line of the workpiece is a pair. It is always clamped by the electrodes 2.3 with a constant pressing force.

When the welding start point of the workpiece is held between the pair of electrodes 2.3, the pair of electrodes 2.3 are guided along the welding line of the workpiece by the robot arm 37 while being energized, and the desired roll Perform spot welding.

When the roll spot welding is completed, the cylinder 18 is activated again, the piston rod 18a of the cylinder 18 is shortened, the pair of electrodes 2.3 are released, and the movable arm returns the roll spot welding machine body 50 to its original position. This completes the roll spot welding cycle.

(Example) Next, an example of the present invention will be described based on FIGS. 1 to 3.

Note that the same parts as in the conventional one are given the same reference numerals and detailed explanations will be omitted.

In the figure, 50 is the roll spot welding machine body; 5
1 is a slide substrate which is a sliding body. Slide board 5
1 side (left side in Figures 1 and 3),
Mounting plates 35, 36 fixed to plaques 10, 11 are attached. 52 is a base, and a pair of guide rails 53 and 54, which are guide members, are fixed to the base 52. Bearings 55 and 56 fixed to the lower surface of the slide board 51 are slidably fitted into the pair of guide rails 53 and 54. Therefore, the slide substrate 51 slides on the pair of guide rails 53 and 54 in parallel to the sliding direction of the rad 4 toward the electrode.

Further, a stopper 57 made of a bar member is fixed to the surface of the slide substrate 51 between the bearing 55 and the bearing 56 fixed to the slide substrate 51. A tip 57a of the stopper 57 is inserted into a stopper hole 58 formed approximately in the center of the base 52. The stopper 57 has a distal end 57a pressed against a stopper surface 58a inside the stopper hole 58 by a lock cylinder, which will be described later, to be locked, thereby suppressing the swinging of the slide board 51.

Since the stopper 57 for locking the slide board 51 is provided on the slide board 51 in this way, the robot arm 37
When the roll spot welding machine main body 50 is moved to a predetermined distance l, high-speed movement becomes possible, which has the effect of improving productivity.

Stopper hole 5 into which the tip 57a of the stopper 57 is inserted
The length of the slide substrate 51 of No. 8 in the sliding direction is the length of the pair of electrodes 2.
, 3, that is, the length is set to be at least longer than the maximum wear amount of the pair of electrodes 2.3. Therefore, the amount of sliding of the slide substrate 51 is controlled by the length of the stopper hole 58.

A lock cylinder 58 is fixed to the upper part of the base, and is used to move the stopper 57 via a slide board. A bushing 60 is attached to the piston rod 59a of the lock cylinder 59.

Reference numeral 61 denotes a robot mounting plate fixed to the base 52, and the roll spot welding machine main body 50 is attached to a movable arm of a robot (not shown), that is, the robot arm 37 via this robot mounting plate 81.

The operation of the roll spot welding machine configured as above will be explained.

Before welding, the roll spot welding machine main body 50 is attached to the robot arm 37 and stands by at its original position.

At this time, the lock cylinder 58 is activated, the piston rod 59a of the lock cylinder 59 is extended, and the button 60 pushes the stopper 57 downward in FIG. 58a (the lower surface of the stopper hole 58 in FIG. 1). In other words, the slide substrate 51 is thereby locked.

In this state, when the object to be welded (not shown) is positioned at a predetermined position, the pair of electrodes 2.3 of the roll spora welding machine main body 50 can grip the welding start point of the object by the robot arm 37. be moved to a certain position. During this time, slide board 5! is locked, so the roll spot welding machine main body 50 can weld the workpiece (
(not shown).

When the pair of electrodes 2.3 move to a position where they can clamp the welding start point of the workpiece, the lock cylinder 59 operates again, shortens the piston rod 59a of the lock cylinder 59, and unlocks the slide board 51. When the piston rod 18a of the pressurizing cylinder 18 extends and the pair of electrodes 2 and 3 sandwich the welding start point of the workpiece, one electrode 2 of the pair of electrodes 2.3 starts welding the workpiece. After contacting the point, it moves further toward the other electrode 3, so that back pressure is generated at this time, and the back pressure is transmitted to the slide substrate 51 via the bracket 10.11. Slide board 51
When back pressure is transmitted to , the slide substrate 51 moves upward in FIG.

When the slide substrate 51 moves upward, the other electrode 3 also moves upward, and together with the one electrode 2, they sandwich the welding start point of the workpiece. This back pressure acts until the electrode pressing force of one electrode 2 and the electrode pressing force of the other electrode 3 become equal.

In other words, the weld line of the workpiece is reliably held between the pair of electrodes 2 and 3 with constant electrode pressure.

When the welding start point of the workpiece is held between the pair of electrodes 2.3, the pair of electrodes 2.3 are guided along the welding line of the workpiece by the robot arm 37 while being energized, and the desired roll Perform spot welding.

When the roll spot welding is completed, the pressure cylinder 18 is operated again, and the piston rod 18a of the pressure cylinder 18 is
is shortened, the pair of electrodes 2.3 are released, and the lock cylinder 53 is also operated, the piston rod 59a of the lock cylinder 58 is extended, the stopper 57 is pushed down by the button 60, and the tip 57a of the stopper 57 is is pressed against the stopper surface 58a of the stopper hole 58 to lock the slide board 51.

When the slide board 51 is locked, the robot arm 3
7, the roll spot welding machine main body 50 is returned to its original position, and one cycle of roll spot welding is completed.

(Effects of the Invention) As explained in detail above, since the present invention has the above configuration, when one electrode of a pair of electrodes comes into contact with the object to be welded, the other electrode follows the one electrode. Since the roll spot welds come into contact with the workpiece, even if a pair of electrodes wears out and the electrode pressure point shifts, it is possible to perform good roll spot welding without damaging the workpiece. can. Therefore, there is no need to correct the roll spot welding machine body, which reduces the burden on the operator and improves productivity.

In addition, the main body of the conventional roll spot welding machine can be used as is without modification, and the tracking means for the other electrode has an extremely simple configuration, making it easy to modify the conventional roll spot welding machine. It is possible to reduce costs and production costs.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the present invention, and is a front view of the roll spot welding machine main body with one bracket removed, Fig. 2 is a side view of the roll spot welding machine main body, and Fig. 3 is a side view of the roll spot welding machine main body with one bracket removed.
4 is a front view of the conventional roll spot welding machine main body with one bracket removed, and FIG. 5 is a plan view of the conventional roll spot welding machine main body. 50... Roll spot welding machine main body 2... One electrode 3... Other electrode 18... Cylinder 18a... Piston rod 37... Robot arm (movable arm) 51... Slide board (Sliding body) 53.54...Guide rail (guide member) patent
Applicant Toyota Motor Corporation Kito Kogyo Co., Ltd. Figure 1

Claims (1)

[Claims] (1) A roll spot welding machine body equipped with a pair of electrodes is attached to a movable arm, a workpiece to be welded is held between the pair of electrodes, and the pair of electrodes is connected to the welding line of the workpiece by the movable arm. In a roll spot welding machine that performs roll spot welding by applying current and applying pressure while guiding the machine along the A roll spot welding machine characterized in that the other electrode of the electrodes is connected to the main body of the cylinder, and the other electrode is connected to a sliding body slidably fitted to a guide member attached to the movable arm.