JPH08197250A - Welding robot - Google Patents

Abstract

PURPOSE: To obtain a robot applicable to job shop work by mounting a teaching device to the tip part of robot arm and detecting precise position and shape with a weld line detecting device. CONSTITUTION: A base, on which a welding robot 1 and robot controller 2 are mounted, is moved near a work 6 with vehicle and is fixed to floor. Further, a weld line to be joined is taught to a teaching device. Next, by mounting a sensor unit to a shaft 12a of a welding torch 12 of welding robot 1 and then by scanning the welding robot 1 along the focus taught by the teaching device 4, the taught data from the teaching device 4 stored based on search data obtained with displacement sensor 50 is corrected. The conditions, by which a welding robot executes welding, such as moving instruction, welding speed, welding current, etc., are set, the job to be executed by the welding robot is automatically prepared by the robot controller 2. Subsequently, the welding is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a so-called teaching / playback type welding robot, and in particular teaches each work point on a work by a teaching device and detects the welding line connecting each work point. The present invention relates to a welding robot that automatically performs welding along this welding line.

[0002]

2. Description of the Related Art Generally, a teaching / playback method is used to teach the operation of a robot. In this teaching method, the teaching pendant (robot operation panel) is manually operated to operate each axis of the robot, and the effector attached to the arm tip of the robot is moved along each work point on the work piece. Teaching is performed by teaching the coordinate positions of the above, creating a program for operating the welding robot, and storing this in the control device of the robot. At the time of reproduction, the programs stored in the robot control device are sequentially read, and the programs are executed to cause the robot to perform a predetermined machining operation.

However, in such a teaching / playback system, since it is necessary to actually move the robot along each work point on the work, it takes time and effort to move the robot to a desired driving position and posture. , Teaching time is huge.

Therefore, in order to perform the teaching work in a short time, there has been proposed a method of teaching using an arm dedicated to teaching without actually moving the robot itself.

For example, in Japanese Patent Laid-Open No. 54-53462, a teaching arm having a shape similar to that of a robot arm is prepared, mounted on a swivel base of the robot, and teaching is performed by moving the mounted teaching arm. I am trying.

Further, Japanese Patent Laid-Open No. 60-221806,
JP-A-60-108908, JP-A-60-124
No. 707, Japanese Patent Laid-Open No. 60-164813, and Japanese Utility Model Laid-Open No. 61-184683, a pseudo robot having a teaching arm having the same structure and size as the arm of the robot that actually performs the working is operated. A method for teaching is disclosed.

[0007]

However, in each of the conventional teaching apparatuses for robots in the above teaching / playback system, the teaching arm of the same size as the arm of the robot performing the machining work is used. Yes, because of its size, operability deteriorates,
Teaching accuracy is also reduced.

Here, the teaching accuracy refers to an error between the position taught by the teaching arm and the actual movement position when the robot is controlled to be located at this teaching position. This error is mainly due to mechanical problems such as the accuracy of the teaching arm as a measuring instrument and the rigidity of the teaching arm and the actual robot arm on which machining work is performed. The greater the error, the greater.

Further, according to the one disclosed in Japanese Patent Laid-Open No. 54-53462, it is necessary to remove the large articulated arm from the swivel base and replace it with a large articulated teaching arm. Therefore, there is also a problem that it takes time for the attachment / detachment work.

The present invention has been made in view of the above, and has excellent operability, good teaching accuracy, and high-precision work position detection prior to welding work.
Accordingly, it is an object of the present invention to provide a welding robot capable of performing accurate welding along a welding line connecting points taught by a teaching device.

[0011]

In order to achieve the above object, a welding robot according to the present invention is equipped with a welding torch at the tip of an articulated robot arm, and the welding torch is a welding line on a workpiece. In a welding robot that is taught by a teaching device so as to be moved along, a pointing tool is attached to the tip of an arm member having a predetermined degree of freedom, and the pointing tool points a welding line on a workpiece. A teaching device adapted to teach the operation of the robot arm and a detection device for detecting a welding line are attached to the distal end of the robot arm by receiving a detection signal from the detection device, The control means is provided to correct the teaching operation by the signal.

The welding robot is mounted on a base that can be moved by moving means such as a moving vehicle.

[0013]

[Operation] The teaching device and the detection device are appropriately attached / detached to / from the tip of the robot arm when teaching the operation of the robot arm of the welding robot. The teaching data by the teaching device is corrected by the control data of the teaching device by the detection data of the detecting device, and the welding torch attached to the tip of the robot arm of the welding robot executes welding based on the corrected data.

[0014]

EXAMPLES Examples of the present invention will be described with reference to the drawings. First, an example of a teaching device used for the welding robot according to the present invention will be described. FIG. 1 is a diagram schematically showing the external appearance of the embodiment device, FIG. 2 is a block diagram showing the configuration of the embodiment device, and FIG. 3 is a diagram showing in more detail the state of the tip of the tip arm of the robot. is there.

As shown in these figures, a welding robot 1 for performing a predetermined working operation is a multi-joint robot having, for example, 6 axes, and a wrist 13 at the tip of a robot arm 1a thereof.
In the same, a 6-axis teaching device (teaching arm), which is the same as the welding robot 1, is detachably arranged. Where the wrist 13
Is rotated by the robot 5th axis with respect to the tip arm 1a as shown by the arrow A'in FIG. 3, and the robot 6th axis rotates the wrist longitudinal center axis as shown by the arrow B '. Is rotated as. A welding torch 12 for performing welding work is attached to the tip of the wrist 13. The welding torch 12 has a shaft 12a at its tip, and the tip 12b moves along the welding line L of the work 6. By doing so, welding work is performed.

A displacement sensor 50 for preliminarily detecting the position and shape of the welding line L of the work 6 before welding is detachably attached to the tip end shaft portion of the welding torch 12. The displacement sensor 50 is a sensor unit 5 shown in FIG.
It constitutes a part of 1. The turning base 1c of the welding robot 1 is provided with a detachable base 55 (described later) on which the sensor unit 51 is placed and locked. The detachable base 55 is within the operating range of the welding robot 1.

The teaching device 4 comprises the axes 42-47 of the device.
It has a position detector 40 for detecting the position of, and is fixed to the wrist 13 by a holding member 41. For example, in FIG.
As shown in FIG. 3, a fixing method in which a ring-shaped holding member 41 is mounted around the wrist 13 and the holding member 41 and the mounting portion 41a of the teaching device 4 are fastened with bolts 41b can be considered. The holding member 41 is always fixed to the wrist side of the robot arm 1a, and the teaching device 4 is attached to the holding member 41.
If the attachment portion 41a of 1 is detachably attached, it is possible to further reduce an error such as a positional deviation when the teaching device 4 is arranged in the welding robot 1. A pointing device 48 is attached to the tip of the arm of the teaching device 4. This indicator 48 is used for the welding torch 1 of the welding robot 1 that performs welding work.
It is equivalent to 2. In this embodiment, the same 6-axis teaching device as the welding robot 1 is used, but the number of axes is not limited as long as the structure is such that the coordinate position and orientation rR of the welding torch 12 described later can be obtained. It may have a different structure from the welding robot.

The position detector 40 of the teaching device 4 outputs a position detection signal indicating the position θT of each of the axes 42 to 47 to the data converter 5. On the other hand, the welding robot 1 is also provided with a position detector 11 for detecting the position of each axis of the robot arm 1a, and a position detection signal indicating the position θR of each axis is sent from the position detector 11 to the robot control unit. It is output to the data conversion device 5 via the monitor unit 23 of the device 2.

In the data converter 5, the above detection signals θ
Taking in T and θ R, these positions θ
A calculation for converting T and θR into the coordinate position and orientation rR of the welding torch 12 at the tip of the robot arm 1a of the welding robot 1 is performed, and this is output to the robot controller 2. In the robot controller 2, the converted coordinate position / orientation rR
Is stored in the storage unit 21.

On the other hand, the detection signal S1 of the displacement sensor 50 is applied to the sensor amplifier 52 and input to the sensor controller 54 via the data converter (A / D converter) 53. As will be described later, the sensor controller 54 generates data indicating the position and shape of the welding line L based on the input detection signal S1 and applies this to the robot controller 2 of the welding robot 1.

The robot control device 2 corrects the teaching data from the teaching device 4 stored in the storage unit 21 based on the position and shape data input from the sensor controller 54.

The robot control device 2 drives the air cylinder 59 (FIG. 5) of the sensor attachment / detachment device on the attachment / detachment base 55, as will be described later.
Is output.

FIG. 5 shows the welding torch 1 for the sensor unit 51.
FIG. 3 is a plan view showing the configuration of an attachment / detachment device that is attached to the welding torch 12 and detached from the welding torch 12. FIG. 6 is C- of FIG.
It is C sectional drawing.

As shown in these figures, the sensor unit 51
Is screwed so that the displacement sensor 50 and the gripper 56 are integrated with each other.
5, stoppers 57 and 58 arranged on the upper surface of the detachable base 55 to lock the sensor unit 51, and an air cylinder 59 arranged on the upper surface of the detachable base 55.

A signal line 50a for the detection signal S1 is connected to the displacement sensor 50 of the sensor unit 51, and the other end of the signal line 50a is connected to the sensor amplifier 52.

The gripper 56 of the sensor unit 51 has a structure in which a pair of members 60 and 61 are rotatable by a pin 62 (see FIG. 6), and is composed of an arm portion 56a and a grip portion 56b.

The grip portion 56b is the shaft 12 of the welding torch 12.
An opening 56c, which is a portion for clamping a, and through which the shaft 12a can be inserted, is formed. An elastic body (for example, rubber) is provided on the inner periphery of the opening 56c to cushion the shaft 12a.
Is affixed.

On the other hand, the arm portion 56a is a portion for changing the size of the opening portion 56c by opening and closing the gripper 56 according to the acting force.

Now, when the rod 59a of the air cylinder 59 is in a retracted state and no external force is applied to the arm portion 56a, the spring 63 interposed between the members 60 and 61 is used. By the elastic force of the arm 56
The tip of a comes into contact with the stoppers 57 and 58, and the entire sensor unit 51 is locked by the stoppers 57 and 58.

However, the rod 59a of the air cylinder 59
When the driving force of the air cylinder 59 acts on the arm portion 56a by being extended and brought into contact with the arm 56a, the driving force overcomes the elastic force of the spring 63 and the gripper 56a.
Is opened and the opening 56c is maximized. Therefore, in such a state, the shaft 12a of the welding torch 12 can be loosely inserted in the opening 56c.

The welding robot 1 is, as shown in FIG.
It is mounted on the base 66 together with the robot controller 2. The base 66 can be moved by a moving vehicle 68. The moving vehicle 68 moves the workpiece 66 close to the work and lowers it on the floor.
It is designed to be stably fixed at 9. The traveling device of the moving vehicle 68 uses wheels or a tracked device.

Next, the operation of the present invention will be described with reference to the flowcharts shown in FIG. First, the base 66 is moved to the vicinity of the work 6 by the moving vehicle 68 (step a), and the base 66 is fixed to the floor surface (step b). Then, the teaching device 4 is attached to teach the welding line (step c). Next, this teaching device 4
The robot control device 2 automatically creates a search job for recognizing an accurate position and shape with respect to the approximate position taught in step (d), and the teaching device 4 is removed.

Next, the sensor unit 51 is attached to the welding robot 1
After the welding robot 1 is mounted on the shaft 12a of the welding torch 12, the welding robot 1 is caused to scan in accordance with the locus taught by the teaching device 4, and the shape recognition function of the displacement sensor 50 recognizes the accurate position and welding shape of the welding line L. Then, the sensor unit 51 is removed (step e).

Then, based on the search data obtained by the displacement sensor 50, the teaching data from the teaching device 4 stored in the storage unit 21 is corrected, and a movement command and a welding command for the welding robot 1 to perform welding are obtained. Conditions such as welding speed and welding current are set, and a job executable by the welding robot 1 is automatically created by the robot controller 2 (step f). Then, welding is performed (step g).

At this time, it is judged whether the welding robot 1 needs to be moved because the work 6 is large and the arm 1a of the welding robot 1 does not reach (step h). If necessary, the above steps ( a) to g) are performed. If it is not necessary to move it, the welding work is terminated.

An example of the processing contents of the teaching device 4 at the time of teaching will be described with reference to the flowchart of FIG. First, the operator
The teaching pendant 3 is operated to operate the welding robot 1. Then, when the welding robot 1 is moved to a position where it can teach each work point on the work 6 within the operating range of the teaching device 4, the welding robot 1 is turned on and turned off. The servo-off state and the brake-on state are measures in consideration of the safety of the operator. Technically, the following processing can be performed even in the servo-on state (step 10).
1).

Next, the teaching device 4 is attached to the tip of the tip arm 1a of the robot 1 by the fixing method shown in FIG. 4, for example (step 102). Then, the operator holds the teaching device 4 by hand (see FIG. 1), and operates a switch (not shown) for storing the point P while pointing the work point P on the work 6 by the pointing tool 48 at the tip. It is turned on (step 103). By this switch operation, the data conversion device 5 moves from the position detector 40 to
The data of the position θT corresponding to the working point P is fetched, and the current position θR of the welding robot 1 is fetched via the monitor 23 of the robot controller 2 (step 10).
4, 105).

Then, the fetched data are combined,
It is converted into coordinate position / orientation data rR representing the position and orientation of the welding torch 12 of the welding robot 1. Here, it is determined whether or not the converted coordinate position / orientation data rR is operable, that is, whether or not it is within the operation range of the welding robot 1 (step 106). When it is determined that the data conversion device 5 is operable, the data conversion device 5 determines that the robot control device 2
The coordinate position / orientation data rR is written in the storage unit 21 (step 107).

The above processing is performed at each work point P on the work 6.
Is repeated and the teaching work is completed (step 108). Now, the coordinate position / orientation data rR is
It is expressed by the following equation (1).

RR = (X, Y, Z, A, B, C) (1) Here, X, Y, Z represent three-dimensional coordinate positions of the tip of the welding torch 12, and A, B, C are It is an angle (for example, a Euler angle is used) representing the attitude of the welding torch 12. The conversion into the coordinate position / orientation data rR is performed by the following equation (2). rR = fTR (θT, θR) (2) where fTR is a function for converting the position data θT, θr of each axis of the teaching device 4 and the welding robot 1 into the coordinate position / orientation data rR of the welding torch 12. Represents This function differs depending on the structures of the welding robot 1, the teaching device 4, and the attachment method of the teaching device 4.

When teaching a large work,
Since the work range is wide, it is necessary to exceed the operating range of the teaching device 4 or operate the teaching device 4 near the end of the operating range. Therefore, it is judged whether or not the operation range of the teaching device 4 is within the predetermined range (step 110), and if it is not within the predetermined range,
It is determined that the teaching device 4 cannot operate (step 11
(No judgment 0), the robot 1 is moved by the teaching pendant 3 so that the teaching work is performed in the central portion of the operation range of the teaching device 4 (step 111).

Here, in the prior art, since the teaching arm having the same shape and size as the arm of the welding robot is used, the operability control is poor near the end of the operation range and near the singular point of the structure. However, according to the embodiment of the present invention, it is possible to always teach in a state where the operability is good. Further, since the teaching device 4 is arranged at the tip of the robot arm, the installation error can be extremely small, and the size and weight can be reduced. As a result, the accuracy of the teaching device is improved, resulting in excellent operability and short time. It enables accurate teaching.

When the teaching work is completed, the operator removes the teaching device 4 from the welding robot 1 by the method shown in FIG. 4 and returns the welding robot 1 to the servo-on state (step 109).

Next, the operation of the displacement sensor 51 in step (e) of FIG. 8 will be described with reference to the flowchart of FIG. First, the control unit 22 outputs a drive control signal S2 to the drive source of each axis of the welding robot, the welding torch 12 is moved as shown by an arrow A in FIG. 1, and the torch tip 12b is moved.
The sensor unit 5 in which the
The gripper 56b of the first gripper 56 is positioned above the gripping portion 56b (step 201).

After the above positioning is performed, the control unit 22 of the welding robot 1 sends the drive control signal S3 to the air cylinder 5
9 is output, the rod 59a is extended, the gripper 56 is opened, and the opening 56c is maximized. Next, the drive control signal S2 is output to each axis of the robot, and the shaft 12a of the welding torch 12 is inserted into the opening 56c to a predetermined position. Next, the drive control signal S3 is output to the air cylinder 59, and the rod 59a is retracted. As a result, the arm portion 56a is pushed back by the spring force, the gripper 56 is closed, and the shaft 12a of the welding torch 12 inserted into the opening portion 56c is gripped by the spring force. Thus, the sensor unit 51 is mounted on the shaft 12a of the welding torch 12 (step 202). Based on the search job automatically created by the welding robot controller 2, the controller 22 outputs the drive control signal S2 to move the welding torch 12 onto the work 6 as shown by arrow B in FIG. Is moved along the welding line L to scan the sensor unit 51 mounted on the torch 12 along the welding line L (step 20).
3). During this scanning, the detection signal S1 of the displacement sensor 50 is sequentially input to and stored in the sensor controller 54 via the sensor amplifier 52 and the A / D converter 53 (step 204). Then, the control unit 22 generates data indicating the shape and position of the welding line L based on the stored scanning data (step 205).

Next, the control unit outputs the drive control signal S2 and moves the welding torch 12 again onto the attachment / detachment base 55 as shown by the arrow A in FIG.
The sensor unit 51 attached to a is positioned between the stoppers 57 and 58 on the removable base 55 (step 20).
6). The drive control signal S3 is output to drive the air cylinder 59, extend the rod 59a, and open the gripper 56. Thereby, the opening portion 56c of the shaft 12a of the torch 12
The gripped state by is released. Next, the drive control signal S
2 is output and the welding torch 12 is moved upward to open the opening 5
The shaft 12a is moved from 6c to a predetermined position. The drive control signal S3 is output to the air cylinder 59 to retract the rod 59a. As a result, due to the spring force, the arm portion 56a
Is brought into contact with the stoppers 57 and 58, and the sensor unit 51
The entire state is again locked by the stoppers 57 and 58 (step 207). In this embodiment,
The data processing of the teaching device 4 is performed by the data conversion device 5,
The data processing of the displacement sensor 50 is performed by the sensor controller 54.
However, the robot controller 2 may perform all the processing. Further, the search job performed by the robot control device 2 includes automatic creation of a welding job, data conversion device 5, and sensor controller 54.
It is also possible to collectively cause the external computer to perform the processing performed in step 1.

[0047]

According to the present invention, the teaching device including the arm member is attached to the tip end portion of the robot arm so that the operability is excellent, the approximate position of the welding line can be taught in a short time, and the welding can be performed. The line detection device can accurately detect the position and shape of the welding line taught by the teaching device before the welding operation. As a result, the welding operation of the welding robot can be taught in a short time, and accurate welding can be performed, so that the welding robot can be applied to a wide variety of small-quantity workpieces that could not be achieved conventionally. Further, by providing a moving means, it becomes possible to apply the robot to large and heavy workpieces which are difficult to move and have complicated shapes.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an example of a welding robot according to the present invention.

FIG. 2 is a block diagram showing a configuration of the embodiment apparatus shown in FIG.

FIG. 3 is a diagram showing in detail the state of the tip of the robot shown in FIG.

FIG. 4 is a diagram illustrating a method for fixing the teaching device of the embodiment to a robot arm.

5 is a view of the detachable base of the displacement sensor shown in FIG. 1 as seen from above.

6 is a sectional view taken along the line CC of FIG.

FIG. 7 is a diagram showing a teaching work state of the welding robot according to the present invention.

FIG. 8 is a flowchart showing a work procedure of the welding robot according to the present invention.

FIG. 9 is a flowchart showing a processing procedure performed by the teaching device.

FIG. 10 is a flowchart showing a processing procedure performed by the displacement sensor.

[Explanation of symbols]

 1 ... Welding robot 1a ... Arm 2 ... Robot control device 4 ... Teaching device 6 ... Work 12 ... Welding torch 13 ... Wrist 50 ... Displacement sensor 51 ... Sensor unit 54 ... Sensor controller 55 ... Attachment / detachment base 66 ... Base 68 ... Mobile vehicle.

Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location B25J 9/22 Z (72) Inventor Matsuo 1200 Manda, Hiratsuka-shi, Kanagawa Komatsu Ltd.

Claims (2)

[Claims] 1. A welding robot in which a welding torch is attached to the tip of an articulated robot arm, and a teaching device teaches the welding torch to move along a welding line on a workpiece. , A teaching device that is equipped with an indicator at the tip of an arm member having a predetermined degree of freedom, and indicates the welding line on the workpiece with the indicator, and a teaching device that teaches the operation of the robot arm, and a welding line. A welding robot characterized in that a detection device for detecting is attached to a tip end portion of the robot arm, and a control means for receiving a detection signal from the detection device and correcting a teaching operation by a signal from the teaching device is provided. . 2. The welding robot according to claim 1, wherein the welding robot is mounted on a base that can be moved by moving means such as a moving vehicle.