JPH0211990Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a spot welding device for welding objects to be welded, such as car bodies, on a conveyor.

(Prior Art) Conventionally, as a spot welding machine for spot welding objects to be welded on a conveyor, there has been known a spot welding machine as shown in Utility Model Publication No. 10469/1983.

This device has a rotary table that can freely move forward and backward in orthogonal directions near a conveyor that transports objects to be welded, such as vehicle bodies, while being fixed. A spot welding machine having welding electrodes moving away from and approaching each other is rotatably mounted on the rotary table, and the welding electrodes can rotate while holding the sill of the vehicle body. After welding is completed, the spot welding machine can be returned to its original position by means of a spring. Projections are protruded from the side of the conveyor at appropriate intervals, and within the area in which these projections move, a switch is provided to open and close the pressure cylinder. The workpiece is clamped and energized.

(Problem to be solved by the invention) However, in such a spot welding machine, the welding electrode is rotated while the workpiece to be welded is held along the conveyor, so only the area near the center of rotation is energized for a predetermined period of time. In addition to weak welding strength due to the inability to secure a sufficient welding area, there were problems such as wear and deformation of the welding electrode, and welding marks that stuck to the welded object. In addition, the welding position is detected using a protrusion on the side of the conveyor and a limit switch, but since the welding position is affected by the tension of the conveyor, there is a problem that precise positioning is not possible, and the entire device is complex and large. There was a problem that.

This invention focuses on this problem, and improves welding quality such as welding strength and welding marks by welding parts to be welded while being transported while being placed on a conveyor, and enables precise welding position setting and change. It is an object of the present invention to provide a spot welding device that can easily carry out welding, has a simple structure, can be easily miniaturized, and has improved work safety.

(Means for Achieving the Object) In order to achieve the object, the spot welding device according to the present invention is arranged along the vicinity of a conveyor, and has an upper welding point extending in the conveying direction of the workpieces on the conveyor. a guide frame having an opening; a guide plate that is slidably fitted onto an inner wall surface of the guide frame, protrudes from the upper opening and reciprocates in the transport direction; and fixed on the guide plate. a spot welding machine equipped with a pair of welding electrodes capable of sandwiching the workpiece from a direction perpendicular to the transport direction, and a pressure cylinder that moves the pair of welding electrodes apart and toward each other, and transporting the workpiece. a buffer member disposed on the upstream side in the direction and abuts against the guide plate to determine a sliding start position of the guide plate; and a buffer member disposed on the downstream side in the conveying direction of the workpiece, the pair of welding electrodes A biasing means that returns the guide plate to the sliding start position when the workpiece is separated after welding, and a plurality of biasing means that rotate in conjunction with the drive shaft of the conveyor and are spaced apart at a predetermined angle from a reference position that determines one rotation. A rotary plate with through holes opened therein; and a detection light is irradiated onto the through holes while the rotary plate is rotating, and information regarding the transportation distance of the welded object is detected as a detection signal by the detection light passing through the through holes. an optical detection means; a pressure cylinder that is provided between the optical detection means and the pressure cylinder, and controls the welding time of the object to be welded by activating and releasing the pressure cylinder based on the detection signal; The present invention is characterized by comprising: a control device; and a limit switch that is disposed behind the normal sliding end position of the guide plate and stops the drive shaft when the guide plate comes into contact with it.

(Example) Hereinafter, an example of this invention will be described based on the drawings.

In FIGS. 1 to 4, a base 1 is fixed to a fixed part such as a floor along a conveyor 2, and a guide frame 3 is fixed to the base 1. The guide plate 4 has an upper opening 3a of the guide frame 3.
The conveyor 2 is slidably fitted in the conveyor 2 and is attached to the conveyor 2 so as to be movable in a direction parallel to the moving direction of the conveyor 2.

As shown in FIG. 4, the spot welding machine 5 is equipped with electrodes 6 (a pair of welding electrodes) facing each other, and the electrodes 6 are opened and closed by a pressure cylinder 7. That is, when the electrodes 6 are in the open state, a member to be welded, such as the sill portion 9 of the car body 8, which has a linear shape with respect to the moving direction of the conveyor 2, can freely pass between the electrodes 6. When the spot welding machine 5 is in the closed state, the welding member is pressed and energized to weld the spot, and the spot welding machine 5 is integrally connected to the welding member by the pressure welding.

A compression spring 10 (biasing means) is attached between the guide frame 3 and the guide plate 4, and while the conveyor 2 is moving in the direction of the arrow 11, the electrode 6 comes into pressure contact with the sill part 9, and the guide plate 4 moves in the direction of the arrow 11 together with the vehicle body 8 against the compression spring 10. When the pressure contact by the electrode 6 is released, the guide plate 4 and the spot welder 5 are returned to their original positions.

The buffer member 12 determines the sliding start position of the guide plate 4, and has a buffer function that acts during this return movement. Limit switch 13
In order to make an emergency stop of the conveyor 2 when the electrode 6 does not separate from the sill part 9 even when the pressurizing cylinder 7 is opened, a position detection switch is installed to detect overrun (backward abnormality) of the guide plate 4. When the protrusion 14 of the guide plate 4 comes into contact with the limit switch 13 and the switch is activated, a separate safety device is activated to bring the conveyor 2 to an emergency stop.

The conveyor 2 has a motor 15 as shown in FIG.
The slat 18 is driven by a speed reducer 16, a main chain wheel 17, etc. The electromagnetic brake 19 is activated when the conveyor 2 is brought to a sudden stop.

FIG. 6 shows the main parts of the welding position setting device 20. This welding position setting device 20 includes a disk-shaped rotary plate 22 that rotates integrally with a shaft 21, and a photocoupler 24 (optical detection means). The shaft 21 that fixes the rotating plate 22 is connected to the main chain wheel shaft 28 via a pulley 25, a timing belt 26, and a pulley 27.
(drive shaft) and rotates synchronously. With this pulley ratio, the unit process pitch of periodic repetition in the welding work process, that is, the movement pitch of the car body 8 disposed on the conveyor 2 in this case, and one rotation of the rotary plate 22 correspond.

A plurality of through holes 23 opened in the rotating plate 22
When a predetermined slat 18 is located in the vicinity of the buffer member 12 (see FIG. 1), the electrode 6 starts to be pressed, and the interval at which the electrode 6 starts to be clamped is set to the axis 2.
It is set by the opening angle of the through holes 23 with 1 as the center. In this embodiment, welding is performed by the number of through holes 23 during one rotation of the rotary plate 22.
Each through hole 23 is spaced apart at a predetermined angle from a reference position that determines one rotation.

The photocoupler 24 emits light (detection light) from one side to the other, and when the emitted light passes through the through hole 23 and is received by the other side of the photocoupler 24, the welding position of the seal portion 9 is detected. Information related to the opening and closing of the pressurizing cylinder 7 is detected, and a position detection signal related to the opening and closing of the pressurizing cylinder 7 is generated.

The cylinder control panel 29 is a control device that operates the pressurizing cylinder 7 to control opening and closing of the electrode 6, and includes a timer, a solenoid valve for air control, and the like. When a position detection signal of the through hole 23 is received from the photocoupler 24 via the photoelectric signal amplifier 30, the pressure cylinder 7 is operated for a predetermined welding time, and the electrode 6 is closed during that time. It should be noted that this welding time is completed with sufficient margin within the movement time of each pitch of the through hole 23. A cylinder operation stop switch 31 is provided in the path from the photocoupler 24 to the cylinder control panel 29, and when welding is not required, this is operated to prevent the pressurizing cylinder 7 from operating. Similarly, the safety plug 32
is provided, and by removing it when polishing the electrode 6, the operation of the pressurizing cylinder 7 is prohibited.

The operation of this embodiment will be explained below.

Before starting the conveyor 2, the mounting position of each car body 8 on the conveyor 2, the rotary plate 22 and the spot welding machine 5
The positional relationship between the rotating plate 22 and the rotating plate 22 has been adjusted normally, and the rotary plate 22 is in a position rotated approximately 180 degrees from the state shown in FIG. At this time, the portion of the rotating plate 22 between the through holes 23 faces the photocoupler 24 and blocks light, and the electrode 6 of the spot welding machine 5 is in an open state.

When the conveyor 2 is started, the rotating plate 22 rotates as the vehicle body 8 moves. and one of the through holes 23
is located between photocouplers 24 and 24, photocoupler 2
4 detects the light and a signal regarding the welding position is sent to the control panel 2.
9, and at the time of detection, the pressurizing cylinder 7 is activated and the electrode 6 begins to clamp the sill portion 9.
When the solenoid valve is air-controlled for a predetermined period of time by the control panel 29, the electrodes 6 sandwich and press the sill portion 9, and the sill portion 9 and the spot welding machine 5 are integrally connected. As the conveyor 2 moves, the spot welding machine 5 and the guide plate 4 move while compressing the spring 10. After a predetermined period of time has elapsed, when the electrode 6 is opened, the spot welding machine 5, together with the guide plate 4, is urged by the spring 10 and returns to the position of the buffer member 12. When the conveyor moves further and the next through hole 23 faces the photocoupler 24, welding is carried out for a predetermined period of time in the same manner as described above, and in the same manner, when welding for the number of through holes 23 is completed, the next car body 8 is welded. The same is repeated.

(Effects of the Invention) Since the spot welding device according to the present invention is configured as described above, welding strength is ensured compared to the conventional device, welding traces are less likely to remain, and the structure is simplified. Moreover, since the present invention uses a rotating plate, it is easy to downsize, and since the welding position is set by the rotating plate, it is easy to set and change the welding position by drilling, closing, etc., and it is also easy to determine the welding position. Can be done precisely. Furthermore, since the present invention uses optical detection means to detect the welding position, it is possible to eliminate welding defects such as failure to perform welding due to contact defects peculiar to mechanical switches. Furthermore, the present invention has the effect of improving safety because the conveyor stops when the limit switch detects an abnormality in the backward movement of the spot welding machine.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the usage state of a device showing an embodiment of this invention, Fig. 2 is a plan view of the welding position setting device, Fig. 3 is a side view seen from the direction of arrow A in Fig. 2, and Fig. 3 is a side view of the welding position setting device. Figure 4 is a cross-sectional view taken along line B-B in Figure 2, showing the installation state of the spot welding machine with virtual lines, and Figure 5 is a front view illustrating the state in which the welding position setting device is installed on the conveyor. , FIG. 6 is a diagram illustrating a schematic configuration of the control device. 2... Conveyor, 3... Guide frame, 4...
...Guide plate, 5...Spot welding machine, 6...
... Electrode (pair of welding electrodes), 9 ... Sill part (member to be welded), 10 ... Compression spring (biasing means), 12 ...
... Buffer member, 22 ... Rotating plate, 23 ... Through hole,
24...Photocoupler (optical detection means), 29...
...Cylinder control panel (control device).

Claims (1)

[Claims for Utility Model Registration] A guide frame disposed along the vicinity of a conveyor and having an upper opening extending in the conveyance direction of the workpieces on the conveyor; a guide plate that is freely fitted and protrudes from the upper opening and reciprocates in the transport direction; and a guide plate that is fixed on the guide plate and is capable of holding the workpiece from a direction perpendicular to the transport direction. a spot welding machine equipped with a pair of welding electrodes and a pressurizing cylinder that moves the pair of welding electrodes apart and toward each other; a buffer member that determines a sliding start position of the guide plate, which is disposed on the downstream side in the conveying direction of the workpiece, and when the pair of welding electrodes separates after welding the workpiece, the buffer member determines the sliding start position of the guide plate; a biasing means for returning the conveyor to the position; a rotary plate that rotates in conjunction with the drive shaft of the conveyor and has a plurality of through holes opened at a predetermined angle from a reference position that determines one revolution; an optical detection means that irradiates the through hole with detection light and detects information regarding the conveyance distance of the welded object as a detection signal by the detection light that passes through the through hole; and between the optical detection means and the pressurizing cylinder. a pressure cylinder control device that controls the welding time of the object to be welded by activating and releasing the pressure cylinder based on the detection signal; and a pressure cylinder control device that is arranged behind the normal sliding end position of the guide plate. and a limit switch that stops the drive shaft when the guide plate abuts the spot welding device.