JPH0193806A - Teaching method for automatic machine tool - Google Patents

Abstract

PURPOSE:To cause a teaching to be exact and easy by using the position information of the same teaching point, which is taught in advance, automatically moving an end effector and after that, adding desired correction when the same or closed point to a taught point is taught again. CONSTITUTION:For a plasma cut-off robot RB, a beam 5 is provided on the top part of a column 6 erected on a base stand 7 and a moving beam 4, which moves in an X direction with a motor M1, is provided on the beam 5. Further, a moving column 3, which moves respectively in Y and Z directions with motors M2 and M3, is provided on the moving beam 4. An arm 2 of an L-character shape, which revolves in a phi direction with a motor M4, is fit to the lower edge of this moving column 3 and a cut-torch 1 is provided on the tip part. When the same or closed point is taught again, an instructing value to correspond to first teaching point position information is given to said driving mechanism and the working point of the torch 1 is moved to the above-mentioned first teaching point. After that, the desired correction is added to the position and attitude of the torch and the information after the correction are fetched as second teaching point information.

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention is directed to teaching automatic machine tools (such as robots) for sequentially teaching a predetermined machine tool the position and orientation of an end effector at a plurality of teaching points. Regarding the method.

(Conventional technology and its problems) Various cutting robots have already been proposed, such as plasma cutting robots, that can three-dimensionally cut workpieces such as three-dimensional structures, shaped steel, and pipes into desired shapes. and has been put into practical use.

In such a robot, in order to teach the robot the cutting line, the cutting torch is manually moved along the cutting line on the workpiece, and the cutting torch is moved at multiple points along the cutting path.
Teaching is performed in which the position and orientation of the cutting torch are sequentially taught as teaching point information. FIG. 6(a) is a conceptual diagram showing the teaching of the cutting line to the cutting robot by such a teaching method, and FIG. 6(b) is a conceptual diagram showing the I-
It is a view taken along the I arrow.

In the figure, the cutting robot RB has three orthogonal axes (X
, Y, Z), has two degrees of freedom as rotation axes (θ, φ), and has a cutting torch 1 as an end effector. FIG. 6 shows teaching to cut a cylindrical workpiece W along a cutting line C using this cutting robot RB.

During teaching, the cutting torch 1 is moved along the cutting line C on the workpiece W (an imaginary line not drawn on the workpiece W may be used).
, and teaches the position and orientation of the cutting torch 1 at a desired point P on the cutting line C.

The cutting FA that is about to be taught in Figure 6
C progresses from the starting point P , P , P , etc., and the ending point P is the starting point P. It forms a closed curve with the same position as .

In such a case, the end point P. When the cutting torch 1 is manually moved and taught to the position P, the cutting starting point P is reached.

and end point P. It is difficult to make the positions P perfectly coincide with each other, and as shown in FIG. 6(b), the position P is usually slightly shifted. ', it was difficult to cut a completely closed curve. Further, there is a problem in that it takes time and effort to correct the positional deviation.

Roughly speaking, there are cases where you want to set the end point at a predetermined position near the start point without making the start point and end point completely match, but even in this case, if you do not know the exact location of the start point, you will not be able to complete the process. Unable to set points accurately. Therefore, even in such cases, the conventional teaching method has the problem of inaccuracy.

(Purpose of the Invention) This invention was made to solve the above-mentioned problems, and provides an automatic machine tool that can accurately and easily teach the same or nearby points again. The purpose is to provide a teaching method.

(Means for Achieving the Object) In the present invention, when the second teaching point is set to be the same as or near the first teaching point that has already been taught, the first teaching point is set in the drive mechanism of the automatic machine tool. After moving the working point of the end effector to the first teaching point by giving a command value according to the position information of the teaching point, desired corrections are made to the position and posture of the end effector, and the corrected The information is taken in as teaching information of the second teaching point.

Note that the term "work point" as used herein refers to a point where work is actually performed based on the operation of the end effector. This may be the tip of the end effector, but in the case of a plasma cutting robot, for example, it corresponds to a cut point located a predetermined distance from the tip of the end effector.

〔Example〕

FIG. 1 is a conceptual diagram showing the mechanical configuration of a plasma cutting robot as an example of a machine tool to which teaching is to be performed to which the present invention is applied.

In the figure, this plasma cutting robot Re has a base 7.
A beam 5 is installed on the top of a column 6 erected above. The beam 5 is provided with a moving beam 4 that moves in the X direction by a motor M1 (not shown), and the moving beam 4 is further provided with a moving column 3 that moves in the Y direction and Z direction by motors M2 and M3 (not shown), respectively. It is being

Furthermore, an L-shaped arm 2 that is rotated in the φ direction by a motor M4 is attached to the lower end of the moving column 3, and a cutting torch 1 as an end effector is provided at the tip of the arm 2. . This cutting torch 1 is rotated in the θ direction by a motor M5 located at the tip of the arm 2. This plasma cutting robot RB has three orthogonal
Axis (X.

This is a 5-axis control robot with two axes of rotation (θ, φ) and two axes of rotation (θ, φ). Cutting point (working point) at the tip of cutting tope 1
The spatial coordinate position of CP is determined by the motor M that defines the displacement of this plasma cutting robot RB in the X-axis, Y-axis, and Z-axis directions.
1. M2. Determined only by the rotation angle of M3, motor M
The spatial coordinates of the cutting point CP do not change due to the rotation around the φ axis by motor M5 and the rotation around the θ axis by motor M5.

That is, these rotation axes θ and φ are used only to define the attitude of the cutting torch 1 at the cutting point CP.

The plasma cutting robot Re also includes a plasma generator 10 that supplies plasma to the cutting torch 1 as other equipment. 8. A control device incorporating a combination, a computer, and other control devices, which will be described later. An operation panel 9 equipped with a keyboard and a display is also provided.

FIG. 2 is a schematic diagram of the electrical configuration of the plasma cutting robot RB shown in FIG. 1. In the figure, a computer 1 built in a control device 8 connects to the operation panel 9 via a bus RL. It is connected to the plasma generator 10, mechanism drive system 20, and the like.

This mechanism drive system 20 is comprised of the above-mentioned motors M1 to M5 and encoders E to E5 that detect the rotation angles of these motors M to M5.

When teaching the cutting line C on the workpiece W, the rotation angles of the motors M1 to M5 are read with encoders E1 to E5 for each teaching point P on the cutting line C, and each rotation information is transmitted to the cutting torch 1. The information is stored in the memory (not shown) of the computer 1 as teaching point information for specifying the position and direction of the point.

Next, using this plasma cutting robot RB, a teaching point P is placed on the workpiece W shown in FIG. ,Pl,...

A case will be described in which a teaching operation is performed along a path formed by a chain of Pos. This route forms a closed curve along the virtual cutting line C.

To teach a completely closed closed curve, end point P of cutting line C. It is necessary to teach the same position as the starting point Po. Therefore, in this embodiment, when teaching about the end point P, the starting point P. The cutting torch 1 is automatically moved using only the rotation angle data of the motors M1 to M3 among the rotation angle data of the motors M-M5 included in the teaching point information taught in . By doing so, the cutting point CP (FIG. 1) located in front of the tip of the cutting torch 1 is automatically displaced to a position corresponding to the starting point Po. However, starting point P. The posture information of cutting torch 1 at
Not used here. Therefore, the attitude of the cutting torch 1 remains the same as the attitude at the previous teaching point P 1 or the attitude immediately before the cutting torch 1 was automatically moved. Therefore, after the cutting torch 1 is moved as described above, the direction of the cutting torch 1 at the end point P is manually adjusted, and then teaching is performed as a teaching point. The detailed procedure of this teaching operation is shown in FIG.

First, when starting teaching, the cutting point CP in front of the cutting torch 1 is set as the starting point P in step S1. After manually adjusting the position, posture, etc. of the cutting torch 1, the teaching point information is taken in and stored in the memory inside the computer 11 in step S2. At this time, the teaching point information that defines the position and orientation of the cutting torch 1 is transmitted from encoders E to E5, which correspond to the rotation angles of the motors M1 to M5, respectively. This is the output data of

Next, the starting point P taught in step S. In order to use the teaching foot point information for later teaching the ending point Pn, the operator selects the starting point P in steps S and S4. is set as the selected teaching point. This setting is the starting point P stored in the memory of the computer 1. A flag indicating that the teaching point information is a selected teaching point may be set on the teaching point information, or the teaching point information may be temporarily stored in a storage area separate from the storage area of the series of teaching point information. You can stay there.

In step S5, the operator determines whether the next teaching point to be taught is a point using the position information of the selected teaching point set in advance (hereinafter referred to as "reproducing the selected teaching point"). That is, if you want to set the cutting torch 1 at the same position as the selected teaching point, perform the procedures from steps 86 to S8; otherwise, proceed to step S9, and if all the teaching points have not been completed, Repeat the teaching operation from step 81 onwards. For example, in FIG. 6, teaching is performed at teaching points P, P, P2...
End point P. Consider a case where the teaching point information of the teaching point Pn-1 immediately before is fetched in step S2, and the reproduction of the selected teaching point is specified in step S5. At this time, in step S6, the cutting torch 1 is
X, Y defining the spatial coordinates of the cutting point CP in front of the tip.

The Z coordinate data is read from the memory, and a corresponding position command value is given to the motor M-M3 to automatically move the cutting toe 1 to that position. At this time, five degrees of freedom (X, Y, Z, θ, φ) define the position and posture of the cutting torch 1.
Among them, the spatial coordinate (X.

The reason why only the degrees of freedom (θ, φ) related to the rotation of the cutting torch 1 are not defined is as follows.

Generally, the rotation axis of the end effector of a robot is often set to be able to rotate 360 degrees or more in order to improve workability. As a specific example, FIG. 4 shows the working range vJ of the rotation axis φ of the plasma cutting robot RB shown in FIG. The operating range φ- to φ1 of the rotating shaft φ is such that it can rotate about an angle of 360"+Δφ. In the range of this margin angle Δφ,
Depending on the relationship with the rotation angle φ in the preceding work, either the φ“ side or the φ− side angle is selected.

Cutting start point P shown in FIG. , the angle of the φ axis is φ shown in FIG. Assuming that, the cutting torch 1 is at the starting point P as shown in FIG. 6(b). Work clockwise from
Go around the area and reach the ending point P. When it reaches , the angle φ of the φ axis becomes φ. Corresponds to -360°. Therefore, the starting point P. If all the teaching point information of is used as the teaching point information of the end point P, the cutting torch 1 will make an incorrect operation (in this case, the cutting torch will be reversed from the point P.-1 before the end point to the end point P. 1 rotation clockwise). Therefore, when moving the cutting torch 1 to the selected teaching point coordinates in step S6, the spatial coordinates (X, Y, Z'')
We will use only the rotation angle data of motors M1 to M3 that defines the rotation angle (θ.

The rotation angle data of motors M and M5 corresponding to φ) is not used.

After that, the direction of the cutting torch 1 is manually adjusted in step S7, and then the teaching point information is captured and stored in the memory in step S8.

By doing this, the end point P. As the position of the cutting point (work point) CP at , it is possible to easily teach a position that completely matches the cutting point CP position at the selected teaching point (starting point P) in terms of spatial coordinates, and the direction of the cutting torch 1 can be easily taught. The settings can also be made appropriate for the work in front of the teaching point.

When all teaching points are completed in this way, teaching ends (step S9).

In the above-mentioned teaching procedure, the teaching point selection operation in step S3 is performed not immediately after the teaching point is taught;
It may be performed immediately before teaching the relevant teaching point, or may be performed during the subsequent teaching operation. If each teaching point information that has already been taken in can be read out arbitrarily by specifying the address, there is no need to identify in advance that it is a selected teaching point, and when teaching the end point, It is also possible to designate the address of point information (or teaching point number, etc.), read out the information, and use it. Furthermore, the point set as the selective teaching point does not have to be the starting point Po.

Furthermore, the point at which the selected teaching point is reproduced does not have to be the end point.

FIG. 5 shows another example of cutting along a cutting line having an open curve, in which the cutting line C' on the workpiece W' is at the starting point Q. teaching point Q1 in the horizontal direction. Proceed according to Q2..., and the position of the teaching point Q that has gone around the workpiece W' is the starting point Q. is consistent with After that, it is further cut in the vertical direction according to the teaching points Q, Qn+1°+2, and so on. In the teaching of this cutting line C', the starting point is Q. is set as the selected teaching point, and the teaching point Q is set as the selected teaching point. This selected teaching point information is played back after teaching. When the teaching point Q0 is at a bent part of the workpiece W' as shown in FIG. 5, or when the teaching point Q is other than a closed curve. If +1 etc. exists, the teaching point information of the selected teaching point is reproduced and the cutting torch 1 is set to the teaching point Q. After moving it to the position, adjust the direction of the cutting torch 1 as appropriate (third
Step S7) in the figure makes it possible to realize smooth cutting that is consistent with the ml cutting operation.

In this way, in the above embodiment, even when two retrieval work points (cutting points CP) pass through the same point on the workpieces w and w', it is easily taught that the respective positions are completely coincident. be able to.

It should be noted that the present invention is not limited to the above-mentioned embodiment, and for example, the following modifications are possible.

■ The degree of freedom is not limited to 5 axes, but also the degree of freedom that defines the spatial coordinates of the work point (cutting point).

It is not limited to only the orthogonal system of Y and Z. However, even in that case, only the degree of freedom information that defines the spatial coordinates of the work point shall be used to reproduce the teaching point information of the selected teaching point, and the degree of freedom information regarding only the posture of the end effector shall not be used. shall be.

If you want to set the end point near the start point, first move the end effector's work point to the start point,
After that, the position and orientation may be corrected, and then the teaching point information of the end point may be imported.

■ It is applicable not only to the robot shown in this embodiment but also to general automatic machine tools.

〔Effect of the invention〕

As explained above, according to the present invention, when a point that is the same as or near a point that has already been taught is to be taught again,
After the end effector is automatically moved using positional information of the same teaching point taught in advance, desired corrections are made and the teaching information is imported, making it possible to accurately and easily teach the same or nearby points. It has the effect of being able to

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram of the mechanical configuration of an embodiment in which the present invention is applied to teaching an industrial robot, Figure 2 is a diagram showing the electrical configuration of the robot in Figure 1, and Figure 3 is an implementation of the present invention. A flowchart showing an example method. Fig. 4 is a diagram showing the operating range of the rotary axis of the robot's end effector. Fig. 5 is a conceptual diagram showing the cutting line and teaching point on the workpiece. Fig. 6 is a diagram showing cutting on the workpiece. It is a conceptual diagram showing the relationship between a line, a teaching point, and an end effector of a robot. RB...Plasma cutting robot,

Claims (2)

[Claims] (1) An automatic machine that teaches the operation of the end effector by moving the end effector along a path consisting of a chain of a plurality of teaching points and capturing position and posture information of the end effector at the plurality of teaching points. A teaching method for a device, wherein when performing the teaching along a chain of the plurality of teaching points, a first position that has already been taught as the position of the end effector is
When teaching a second teaching point that is the same as or near the teaching point, the machine tool is driven by a command value that corresponds to the position information already obtained for the first teaching point. After moving the end effector to a position corresponding to the first teaching point by applying a command to a mechanism, a desired modification is made to the position and/or command of the end effector, and the position and orientation information after the modification is obtained. A teaching method for an automatic machine tool, characterized in that the following is taken in as teaching information regarding the second teaching point. (2) The automatic machine tool is a robot having orthogonal axes that define the position of the working point of the end effector as degrees of freedom, and a rotation axis that defines the attitude of the end effector, and the automatic machine tool is a robot that has the second teaching. When teaching points,
2. The method of teaching an automatic machine tool according to claim 1, wherein the end effector is moved using only the position information of the orthogonal axis of the first teaching point.