JPH0627273Y2 - Welding robot equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a welding robot apparatus, and more particularly to a welding robot apparatus capable of preventing distortion of a work due to wear of electrodes. .

[Conventional technology]

For example, in a spot welding robot used to weld a car body of an automobile, a welding unit supported by the robot body sequentially follows each welding point of the car body according to a schedule stored in a control unit of the welding robot in advance, and at each welding point. It is configured to weld the workpieces together. The welding unit includes a gun, a fixed electrode fixed to the gun, and a moving electrode that moves forward and backward with respect to the fixed electrode.

By the way, the position of the work taught to the welding robot and the actual position of the work are the electrode neutral position due to the manufacturing dimensional error of the work and the consumption of the electrodes, that is, the center position of the position where both electrodes hold the work. Variations do not always match. In order to correct these errors so that both electrodes match the actual work position, for example, Japanese Patent Publication No. 62-
As disclosed in Japanese Patent No. 35867, the arm of the robot main body is provided with an equalizer for supporting the welding unit in a floating manner so that the welding unit can be moved in the opposite direction of both electrodes.

[Problems to be solved by the device]

In the conventional welding robot described above, if the wear of the electrode is within a range that can be absorbed by the equalizer,
The position correction function of the equalizer corrects the positions of both electrodes to an appropriate position with respect to the work, but when the electrode wear exceeds that range, the moving electrode is moved from one side of the work to the fixed electrode on the other side of the work. When pressed against, the work may be locally deformed to the fixed electrode side beyond the elastic deformation region to the plastic deformation region, and strain may remain after the welding is completed.

The present invention has been made in consideration of the above circumstances,
An object of the present invention is to provide a welding robot apparatus capable of preventing the occurrence of work distortion due to electrode wear.

[Means for Solving the Problems]

A welding robot according to the present invention employs the following means in order to achieve the above object in a welding robot apparatus in which a welding unit is floatingly supported by an arm of a robot body via an equalizer.

That is, an electrode position correction device that displaces the position of the welding unit with respect to the arm in the electrode facing direction between the arm and the welding unit, a wear amount detection device that detects the wear amount of the fixed electrode of the welding unit, and this wear amount. And a control device that operates the electrode position correction device so as to correct the position of the fixed electrode with respect to the arm to the initial position based on the amount of electrode wear detected by the detection device.

[Action]

With the above configuration, the consumption of the electrode increases in accordance with the number of times the welding operation is repeated. For example, when the welding operation is repeated an appropriate number of times, the consumption amount (wear amount) of the electrode is detected by the wear amount detection device. The position of the fixed electrode can be returned to the initial position by operating the electrode position correction device by the control device based on the detection result of the wear amount detection device to displace the position of the fixed electrode with respect to the arm in the electrode facing direction.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

The spot welding robot is used for welding body panels of a monocoque body of an automobile, and includes a robot body 1, a welding unit 2, and a position correction unit 3 for connecting the welding unit 2 to a terminal arm 11 of the robot body 1. Is equipped with.

As shown in FIG. 1, the welding unit 2 includes a gun 21
A fixed electrode 22 fixedly supported on the lower end thereof, and a movable electrode 24 supported on the upper part of the gun 21 so as to be vertically movable toward and away from the fixed electrode 22 via a pressure cylinder 23.
And a welding current is supplied from the outside via a cable. Further, the fixed electrode 22 and the moving electrode 24 are polished, for example, at every 300 times of hitting points in order to suppress the fluctuation of the welding condition within a certain range.

As shown in FIG. 1 to FIG. 3, the position correction unit 3 described above shows the actual position of the work taught by the robot body 1 and the actual position when the consumption amount of both electrodes 22 and 24 is within the allowable range. The number of weldings of the equalizer unit 4 and the welding unit 2 for eliminating the deviation of the neutral points of both electrodes 22 and 24 caused by the error of the work position and the consumption of both electrodes 22 and 24, that is, the number of welding points is predetermined. Both electrodes 22 and 24 caused by consumption of both electrodes 22 and 24 when the value exceeds the value
And a shift cylinder unit 5 for eliminating the deviation of the neutral point.

As shown in FIGS. 2 and 3, the equalizer unit 4 includes a unit mounting plate 41 connected to an upper portion of the gun 21 and a pair of upper and lower connecting frames 42 connected to the unit mounting plate 41.
.A pair of left and right guide posts 44 fixed via 43
44, an equalizer cylinder 45, and a spring 46.

The equalizer cylinder 45, as shown in FIG.
Body 45a slidably fitted on both guide bosses 44
A cylinder chamber 45b formed in the body 45a and opened downward, a piston 45c slidably inserted in the cylinder chamber 45b, and a pressure receiving chamber 45d defined by the piston 45c in the cylinder chamber 45b. Equipped with.
The pressure receiving chamber 45d is connected to the compressed air supply source 7 shown in FIG.
The internal pressure of the pressure receiving chamber 45d pushes the piston 45c against the lower coupling frame 43 to urge the unit mounting plate 41 downward with respect to the body 45a.

The spring 46 is inserted between the body 45a and the upper connecting frame 42, widens the space between the body 45a and the upper connecting frame 42, and urges the unit mounting plate 41 in the direction of raising the unit mounting plate 41 with respect to the body 45a. It is like this.

The shift cylinder unit 5 includes a shift cylinder 51.
And an arm mounting plate 52 connected to the terminal arm 11, the shift cylinder 51 is slidable on both guide posts 44 below the equalizer cylinder 45, as shown in FIGS. 2 and 3. An externally fitted body 51a, a cylinder chamber 51b formed in the body 51a, a piston 51c slidably inserted in the cylinder chamber 51b and connected to a body 45a of the equalizer cylinder 45, and a cylinder The chamber 51b includes a pressure receiving chamber 51d defined below the piston 51c, a spring chamber 51e defined above the piston 51c in the cylinder chamber 51b, and a spring 51f inserted in the spring chamber 51e. Then, the pressure receiving chamber 51d is connected to the compressed air supply source 7,
The internal pressure causes the piston 51c, the equalizer cylinder 45, the spring 46, and the unit mounting plate 4 to move against the body 51a.
1 is urged in the direction of rising, while the spring 51e
Then, the piston 51c, the equalizer cylinder 45, the spring 46, and the unit mounting plate 41 are urged toward the body 51a in the direction of lowering them.

The arm mounting plate 52 is connected to the body 51a of the shift cylinder 51.

The spot welding robot further includes an electrode position correction control unit 6 for controlling the shift cylinder unit 5 as shown in FIG.

The electrode position correction controller 6 includes a wear amount sensor 61 that detects the wear amount of the fixed electrode 22, a wear amount detection device 62 that performs signal processing of the detection result, and a cylinder control device 63.

The wear amount sensor 61 may be configured to be able to detect the wear amount of the fixed electrode 22 of the welding unit 2 that has been moved to a predetermined position after finishing the polishing every 300 hitting points. The light emitting element 6 is not particularly limited, but for example, the light emitting elements 6 are arranged at predetermined positions so as to face each other.
1a and an image sensor 61b composed of a CCD.

The wear amount detecting device 62 uses the data as the wear amount sensor 61.
Is input to calculate the amount of wear of the fixed electrode 22, and the amount of wear is used as a correction operation amount of the shift cylinder 51 to output a control signal to the cylinder control device 63.

The cylinder control device 63 is interposed between the pressure receiving chamber 51d of the shift cylinder 51 and the compressed air supply source 7, and inputs a control signal to make the internal pressure of the pressure receiving chamber 51d correspond to the correction operation amount of the shift cylinder 51. Then, the shift cylinder 51 is extended to elevate the equalizer unit 4 and the welding unit 2 with respect to the arm mounting plate 52, and the position of the tip of the fixed electrode 22 is initially set to the initial position when the tip of the fixed electrode 22 is arranged. It is configured to be raised to a position.

The welding robot is designed to move the gun 21 to a predetermined wear amount detection position in order to detect the wear amount of the fixed electrode 22 every 300 hits, for example.

In the above configuration, for example, when the number of dots is 300, the fixed / moving amount electrodes 22 and 24 are polished, and thereafter,
The welding unit 2 is moved to a predetermined position, and the wear amount sensor 61 detects the wear amount of the fixed electrode 22. Then, a control signal corresponding to the wear amount of the fixed electrode 22 detected by the wear amount sensor 61 is output from the wear amount detecting device 62, and the cylinder control device 63 that has received this control signal is input.
Extends the shift cylinder 51 to raise the equalizer unit 4 and the welding unit 2 with respect to the arm mounting plate 52, and the position of the tip of the fixed electrode 22 is set to the fixed electrode 2 first.
Raise to the initial position where the tip of 2 is placed.

This prevents the position of the tip of the fixed electrode 22 from deviating from the initial value by a certain amount or more, so that the distance that the moving electrode 24 can press the work toward the fixed electrode 22 side during welding is suppressed within the elastic deformation region of the work. It is possible to eliminate the residual strain after welding. Further, since the position of the tip of the fixed electrode 22 is corrected by correcting the position of the welding unit 2 with respect to the terminal arm 11 of the robot body 1, the control program of the robot body 1 for correcting the position of the tip of the fixed electrode 22. The position of the tip of the fixed electrode 22 can be easily corrected without changing the position.

Next, a spot welding robot according to another embodiment of the present invention will be described with reference to FIG.

In this embodiment, the position correction unit 13 connecting the welding unit 2 to the terminal arm 11 of the robot body 1 is composed of an equalizing unit 14 and a shift unit 15.

The equalizing unit 14 is the same as in the above embodiment.
Unit mounting plate 141 connected to the upper portion of the gun 21
And a pair of upper and lower connecting frames 142 on the unit mounting plate 141.
A pair of left and right guide posts 14 fixed via 143
4, an equalizer cylinder 145, and a spring 146.

The equalizer cylinder 145 has two guide posts 14
4, a body 145a slidably fitted to
Cylinder chamber 145 formed in 5a and opened downward
b and a piston 145c slidably inserted in the cylinder chamber 145b, and the spring 146 is inserted between the body 145a and the upper connecting frame 142 so as to act in a direction to widen the distance between them. Then, the piston 145c is received by the lower connecting frame 143. Pressure receiving chamber 145 divided into cylinder chamber 145b by piston 145c
d is connected to a compressed air supply source (not shown).

Further, unlike the above-described embodiment, the shift unit 15 is fixed to the connecting plate 151 fixed to the body 145a of the equalizing unit 14 and the connecting plate 151 via a pair of upper and lower connecting frames 152 and 153. A pair of left and right guide posts 154, a shift cylinder 155, and a spring 15
6 and an arm mounting plate 157.

The shift cylinder 155 includes a body 155a slidably fitted on both guide posts 154 and a body 155a.
Cylinder chamber 155b formed inside and opened downward
And a piston 155c slidably inserted into the cylinder chamber 155b, and an arm mounting plate 157 is fixed to the body 155a thereof. The spring 156 is the body 1
55a and the upper connection frame 152, and the two are separated from each other to separate the connection plate 151 from the arm attachment plate 157.
It is designed to urge in the direction of raising. Also,
The pressure receiving chamber 155d divided into the cylinder chamber 155b by the piston 155c is connected to a compressed air supply source (not shown), so that the shift cylinder 155 uses the internal pressure of the pressure receiving chamber 155d to connect the piston 155c of the shift cylinder 155 to the lower connecting frame. 153 to press the arm mounting plate 15
The connecting plate 151 is urged in a downward direction with respect to 7. Further, the spring 156 is used for the upper connection frame 15
2 and the body 155a are inserted between the arm mounting plate 1
The connecting plate 151 is urged against 57.

In other configurations of this embodiment, the cylinder control device 63 shortens the shift cylinder 151, and the spring 156 raises the equalizer unit 4 and the welding unit 2 with respect to the arm mounting plate 52, and the position of the tip of the fixed electrode 22 is set to the first position. It is the same as the above-mentioned embodiment except that the tip of the fixed electrode 22 is raised to the initial position. Also, the action and effect thereof are the same as those in the above-described embodiment except the difference in whether the shift cylinder 51 is extended or the shift cylinder 155 is shortened, and thus the description thereof will be omitted.

In each of the above-mentioned embodiments, the detection of the wear amount of the fixed electrode 22 and the correction of the position thereof are performed at the time of polishing the both electrodes 22 and 24 so as not to lower the operating rate of the welding robot. The timing of detecting the wear amount of the electrode 22 and correcting the position thereof is not particularly limited,
The wear amount of the fixed electrode 22 can be detected and its position can be corrected at any time.

[Effect of device]

As described above, in the welding robot according to the present invention, in the welding robot device in which the welding unit is floatingly supported on the arm of the robot body through the equalizer, the position of the welding unit with respect to the arm is set between the arm and the welding unit. An electrode position correction device for displacing in the electrode facing direction, a wear amount detection device for detecting the wear amount of the fixed electrode of the welding unit, and an arm for the electrode position correction device based on the electrode wear amount detected by the wear amount detection device. And a control device that operates so as to correct the position of the fixed electrode with respect to the initial position.

Thus, the electrode position correction device, the wear amount detection device,
Since the control device is provided, the wear amount detection device detects the wear amount of the fixed electrode, and the control device controls the electrode position correction device to correct the position of the welding unit with respect to the arm. As a result, the variation of the position of the fixed electrode with respect to the arm due to the consumption of the fixed electrode is kept below a certain level, and the deformation amount of the work pressed by the moving electrode against the fixed electrode is limited within the elastic deformation region, so that the work is deformed. Can be prevented.

Further, since the position of the welding unit with respect to the arm is corrected, there is no need to change the control program of the robot body that controls the operation of the arm, and the position of the fixed electrode can be easily corrected.

[Brief description of drawings]

1 to 3 show an embodiment of the present invention. FIG. 1 is a configuration explanatory view showing a configuration of a main part of a welding robot. FIG. 2 is a vertical sectional front view of the position correction unit. FIG. 3 is a vertical side view of the position correction unit. FIG. 4 is a vertical sectional side view of a main part of a welding robot showing another embodiment of the present invention. 1 is a robot body, 11 is a terminal arm, 2 is a welding unit, 4 is an equalizer unit, 5 is a shift cylinder unit, 14 is an equalizing unit, 15 is a shift unit, 61 is a wear amount sensor, 62 is a wear amount detecting device, 63
Is a cylinder controller.

Claims (1)

[Scope of utility model registration request] 1. A welding robot apparatus in which a welding unit is floatingly supported on an arm of a robot body via an equalizer, and an electrode position for displacing the position of the welding unit with respect to the arm in the electrode facing direction between the arm and the welding unit. A correction device, a wear amount detection device for detecting the wear amount of the fixed electrode of the welding unit, and the electrode position correction device based on the wear amount of the electrode detected by the wear amount detection device for setting the position of the fixed electrode with respect to the arm to the initial position. And a control device that operates so as to correct the welding robot device.