JP2646890B2 - Control method of laser cutting robot - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling a laser cutting robot provided with a controller for moving a light emitting optical system by measuring a shift between a focal position and a work surface.

[0002]

2. Description of the Related Art In recent years, laser cutting robots have been widely used due to an increase in demand for cutting a three-dimensional work, a high processing accuracy, and a small installation area.

Conventionally, this type of laser cutting robot generally has difficulty in ensuring the accuracy of a workpiece in the case of three-dimensional cutting compared to the processing of a two-dimensional flat plate. When the robot moves, there is a high risk that the tip of the laser beam emitting optical system will collide with the workpiece. Therefore, the teaching point is shifted in advance in the direction in which the distance between the leading edge of the emitting optical system and the surface of the workpiece becomes wider. After that, the deviation between the focal position of the laser beam and the work surface is measured with a sensor, and the emission optical system is slid on the same axis as the laser beam emission direction to correct the deviation and cut. Has started.

[0004]

However, such a conventional laser cutting robot has the following problems.
In other words, the teaching time is lengthened because the worker teaches while shifting the cutting start teaching point in a direction in which the distance between the tip of the laser light emitting optical system and the surface of the work is increased.

In addition, since the slide operation of the emission optical system corrects the operation amount of each operation axis controlled by teaching playback or NC control, a plurality of operation axes must be operated according to the result of a complicated calculation depending on the posture. The control algorithm must be complicated. In addition, these operating axes require a relatively large operating range to secure a work area, and the operating axes close to the fixed part of the robot must also secure strength and rigidity. Also, the response speed becomes slow due to a large time constant. Furthermore, it is desirable to teach that the deviation between the focal position of the laser beam and the surface of the work is as small as possible in order to obtain good processing results. Because of the shift, even if there is no shift of the work, the robot must always correct a large shift amount, and the machining quality is reduced.

An object of the present invention is to solve the above-mentioned conventional problems, and to provide a method of controlling a laser cutting robot capable of improving the processing quality of a three-dimensional laser cutting process in which it is difficult to secure work accuracy and shortening a teaching time. Aim.

[0007]

In order to achieve the above object, the present invention provides a slide shaft provided at the tip of a robot,
An emission optical system that is fixed to the slide axis and emits laser light, a driving unit that moves the slide axis up and down, a sensor that is provided on the emission optical system, and measures a distance from a work surface; laser cutting pressure with a control device for controlling the drive means to input signals
In the robot control method, move the tip of the robot.
At the time of teaching the motion trajectory, the slide axis is moved to a reference position that is a relative position with respect to the tip of the robot and is a reference for the movement of the slide axis, and teaching is performed while maintaining the slide axis. The slide shaft is moved from the reference position in a direction in which the distance between the work surface and the emission optical system is increased by a predetermined moving amount .
Work surface at a position separated by the previously set travel distance
From the direction away from the
Laser cutting is performed while controlling the driving means .

[0008]

In the method described above, the slide shaft is moved to the reference position during teaching, and during operation, the slide shaft is moved by a predetermined amount of movement when the robot moves to the teaching start teaching point and the output surface. since moving from the direction to the reference position where the distance is widened between the systems, teaching
When the operator indicates, the tip of the emission optical system (robot)
Teaching work without being aware of the collision between
In both cases, even if the work is shifted, the shift amount
Can be corrected, and useless correction operation to avoid collision is indispensable.
No longer needed .

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
This will be described with reference to FIG.

As shown in FIG. 1, the laser cutting robot comprises a robot 1, a control device 2 for controlling the robot 1, a laser oscillator 3, and the like.
The laser light oscillated inside is guided to the distal end of the robot 1 through the optical fiber 4 as a transmission path, and the laser light is emitted from the distal end of the robot 1 to perform a cutting process.

A hollow slide shaft 5 is attached to the tip of the robot 1, an emission optical system 6 is fixed to the slide shaft 5, and a sensor 7 is attached to the tip. The sensor 7 is of a capacitance type, and the deviation between the focal position of the laser beam and the work surface is measured.
Is input to Further, a motor 8 is provided as a driving means for moving the slide shaft 5 up and down. The rotational driving force of the motor 8 is the pulleys 9 and 10, the timing belt 11
Thus, the rotational driving force is transmitted to the ball screw 12 and converted into a linear driving force. Ball screw 12 is bearing 13
The output side of the ball screw 12 is fixed to the operation-side member 15 via a through hole. The slide shaft 5 is fixed to the operation side member 15, is supported by a linear motion bearing 16, and can slide up and down.

As described above, in the embodiment, the position of the point P at the tip of the robot 1 obtained as a result of the teaching playback or the operation of each operation axis controlled by the NC is not changed, and the position is the same as the emission direction of the laser light. The output optical system 6 is independently slid up and down on the axis C as indicated by the arrow B.

In the above configuration, the robot 1 shown in FIG.
Will be described. That is, (a) is an operation start point, (b) is a cutting start point, (c) is a cutting end point,
(D) shows the operation end point, respectively, and the center position is P
Move like 0, P1, P2, P3. L is a straight line representing the surface of the work, and this straight line and the exit optical system 6
It is assumed that when the distance from the tip of the laser beam is WD, the surface of the work and the focal position of the laser beam coincide.

In the operation of the robot 1 taught or instructed by teaching or NC, if the surface of the work is straight, the line connecting P1 and P2 is naturally a straight line. It operates as indicated by P2 and P3.

However, if there is an error in the work and the line representing the work surface is shifted upward by WD or more like L ′, P
When the robot 1 reaches one point, the tip of the emission optical system 6 collides with the workpiece.

Conventionally, as a measure for preventing the collision, if the maximum displacement of the work is set to WD + X at the time of teaching, a method of performing teaching by leaving the workpiece further upward by X is adopted. I had to be aware of the teaching work. Further, according to the conventional method, even when there is no error in the work, at the time of operation, the operation amount of each operation axis controlled by teaching playback or NC is corrected to correct the point P1 downward by X. I had to.

According to the embodiment, at the time of operation, when the robot 1 is operated at the cutting start teaching point P1, the slide shaft 5 is moved by a predetermined movement amount X between the work surface L and the emission optical system 6. Is a position relative to the tip of the robot 1 above by X in the direction in which
The slide axis 5 is automatically moved from a reference position , which is a reference for the movement of the ride shaft 5, and at the time of teaching, since the slide shaft 5 is moved to the reference position, the teaching operator teaches without being conscious of a work error. Work can be done. Also, the robot 1 may perform the operation as taught irrespective of the work error, and the work error is corrected by operating the slide shaft 5 by the work error amount. No longer needed.

FIG. 4 is a diagram showing a state when the robot reaches the cutting start point P1 during operation, and FIG. 5 is a diagram showing a state when the cutting is actually started. 4 and 5 show a state where there is no work error. In FIG. 4, the teaching at the point P1 is taught in a state where the slide shaft 5 is moved to the reference position. During operation, the slide shaft 5 is moved upward by a predetermined movement amount X, so that the light is emitted. The distance between the tip of the optical system 6 and the work surface is WD + X
Therefore, even if the workpiece is displaced upward, no collision can occur if the displacement is equal to or less than WD + X. Thereafter, the deviation between the focal position of the laser light and the work surface is measured by the sensor 7, and as shown in FIG. 5, the laser emission optical system 6 is adjusted so that the distance between the tip of the emission optical system 6 and the work surface becomes WD. To the slide shaft 5 as shown by the arrow A.
The cutting is started after the work surface and the focal position of the laser beam coincide with each other.

In this embodiment, the emission optical system 6 is always moved upward by the slide shaft 5 and retracted by X in a state other than during cutting, so that at points P2, P1 and P
The operation is completely opposite to the operation at the point 1 '. During operation, the emission optical system 6 is also moved upward at the operation start point P0 and the operation end point P3 in the same manner as the state at the point P1, and is slid away.

In this embodiment, the sensor 7 is described as a capacitance type sensor. However, if the sensor 7 can measure the distance between the focal position and the surface of the work, such as an eddy current type, a laser type, or the like. good.

[0021]

As is apparent from the above-mentioned conventional example, the control method of the laser cutting robot according to the present invention uses a slide shaft provided at the tip of the robot, and an emission optical system fixed to the slide shaft and emitting laser light. Driving means for moving the slide shaft up and down; and
A sensor for measuring the distance to the surface of the workpiece, and a control device for inputting a signal from the sensor and controlling the driving means .
And the relative position and is a reference of the movement of the slide axis
It becomes the reference position to move the slide shaft, in operation, between the emitting optical system as previously have been set movement amount by the slide shaft work surface when the tip of the robot machining start teaching point has moved The method is to move from the reference position in a direction in which the distance is widened, and by using this method , the teaching work can be performed without the worker being aware of the collision between the tip of the optical system and the work when teaching. In addition, since the robot is taught at the position of the original cutting start teaching point, if the work is displaced, it is only necessary to correct only the deviation amount, and a remarkable improvement in the responsiveness of the work error correction operation can be obtained. In particular, it is possible to shorten the teaching time and improve the processing quality of three-dimensional laser cutting, which is difficult to secure work accuracy.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a laser cutting robot according to an embodiment of the present invention.

FIG. 2 is a side view of the laser cutting robot.

FIG. 3 is an explanatory diagram of the operation of the laser cutting robot.

FIG. 4 is a diagram showing a state where the arm tip of the laser cutting robot has reached a cutting start point P1 during operation.

FIG. 5 is a diagram showing a state in which the tip of an arm of the laser cutting robot is at the start of cutting.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Robot 2 Control device 5 Slide axis 6 Emission optical system 7 Sensor 8 Motor (drive means)

Claims (1)

(57) [Claims] 1. A slide shaft provided at a distal end portion of a robot, an emission optical system fixed to the slide shaft for emitting laser light, a driving unit for moving the slide shaft up and down, and provided on the emission optical system. Laser cutting comprising a sensor for measuring the distance to the work surface, and a control device for inputting a signal from the sensor and controlling the driving means.
In the control method of the processing robot ,
At the time of teaching the movement trajectory, the slide axis is moved to a reference position which is a relative position with respect to the tip of the robot and which is a reference of the movement of the slide axis, and is maintained and taught.
Performed indicates, during operation, hail from the reference position only the sliding axis motion amount that is set in advance in the direction in which the distance between the workpiece surface of the emitting optical system is widened
The work table is set at a position separated by the preset travel distance.
Move from a direction away from the surface, start cutting,
Performing laser cutting while controlling the driving means.
Characteristic laser cutting robot control method.