JPH0426194Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention is a processing robot that processes a workpiece using a rotating tool such as a brush.
The present invention relates to a processing robot control device that performs correction according to tool wear.

[Prior Art] Conventionally, in a control device for a processing robot that processes a workpiece using a rotary tool such as a brush, a spindle motor (first motor) that drives the tool is used.
Press the tool against a reference plane on the workpiece surface or a reference plane parallel to this so that the load current becomes a constant set value, and machine the workpiece surface according to the pushing amount (depth of cut) at this time. A machining robot apparatus is known that repeats this process in units of processing in which the process is performed after correcting the path.

In such a robot device, when the tool is pressed against the reference surface and the load current of the first motor for driving the tool reaches a constant set value, the amount of pushing of the tool into the reference surface (tool tip When the amount of push-in after the tool contacts the reference surface is input from the tool position detector into the control device, the tool needs to be pushed against the reference surface at a low speed due to the responsiveness of the control system. For this reason, when acquiring the pushing amount, the tool approaches the reference surface at high speed, and after approaching, moves at low speed.

[Problems to be solved by the invention] However, in such a robot device, the tool position where the moving speed of the tool is switched from the high speed to the low speed, that is, the deceleration position, is usually constant. As the amount of tool wear increases with the increase in the number of times, the distance between the position near the workpiece that is originally preferable for deceleration and the position where deceleration is actually performed increases as the tool is used. As a result, the distance traveled at low speeds becomes longer, which inevitably increases the overall machining time.

This invention aims to solve the above points,
The aim is to shorten the machining time by shortening the tool movement time as described above.

[Means for Solving the Problems] That is, the present invention made to achieve the above object, as illustrated in FIG. 1, includes: a first motor M2 that drives a tool M1; a current detection device M3 that detects a current value of the current value, compares the current value with a set value, and outputs a detection signal when the current value is greater than or equal to the set value; and a robot arm M4 to which the tool M1 is attached. a second motor M5 that drives the robot arm M5; a position detector M7 that detects the position of the tool M1 in the direction in which it is pressed against the workpiece M6; and a position detector M7 that detects the position of the tool M1 in the pressing direction against the workpiece M6; a high-speed drive means M8 that causes the tool M1 to approach a reference plane of the workpiece M6 or a reference plane parallel thereto at high speed; and the position detected by the position detector M7 due to the operation of the high-speed drive means M8. When the position of the tool M1 reaches a preset deceleration target position near the reference plane, the high-speed drive of the robot arm M4 is switched to low-speed drive, and the tool M1 is pressed against the reference plane at a low speed. When a detection signal is output from the current detection device M3 during operation of the means M9 and the low speed drive means M9, the operation of the low speed drive means M9 is stopped and the position detector M
A tool stop position reading means M10 reads the stop position of the tool M1 from 7, and a deviation between the tool stop position read by the tool stop position reading means M10 and a tool stop teaching position taught in advance is calculated, and the deviation is calculated based on the deviation. a machining path correction means M11 that corrects a machining path preset for the machining surface of the workpiece according to the processing; and controlling the second motor M5 according to the correction result of the machining path correction means M11. A processing robot control device comprising: processing control means M12 for processing the workpiece M6 by
A machining robot control device characterized in that a deceleration target position correction means M13 is provided for correcting the deceleration target position at which high-speed drive is switched to low-speed drive in step 4 based on the deviation between the tool stop position and the tool stop teaching position. The gist is:

In the above configuration, the tool M1 refers to a rotationally driven brush or the like, and has the property that as the number of times it is used increases, its length at least in the pressing direction becomes shorter due to wear. The position detector M7 may be of any type, such as a potentiometer type or a photoelectric conversion type, as long as it can detect the position of the tool.

[Function] In the processing robot control device of the present invention configured as described above, first, the high-speed drive means M8:
The second motor M5 drives the robot arm M4 at high speed to bring the tool M1 close to the reference plane of the workpiece M6 or a reference plane parallel to this at high speed. When the deceleration target position near the surface is reached, the low-speed drive means M9 switches the high-speed drive of the robot arm M4 to low-speed drive, and presses the tool M1 against the reference surface at low speed.

Next, when the low speed drive means M9 is operated, when the current detection device M3 outputs a detection signal indicating that the current value of the first motor M2 is higher than the set value, the tool stop position reading means M10 is activated. , the operation of the low-speed drive means M9 is stopped, and the current position (stop position) of the tool M1 is read from the position detector M7. That is, as the low-speed drive means M9 presses the tool M1 against the reference surface at low speed, the load torque applied to the first motor M2 increases in accordance with this pressing force, and accordingly, the load current of the first motor M2 increases. increases, the tool stop position reading means M10
is the tool M1 at the time when this current value becomes the set value
By reading the position, the tool position where the machining torque of the tool M1 with respect to the reference surface becomes a predetermined value is detected.

When the tool stop position reading means M10 reads the stop position of the tool M1, the machining path correction means M11 calculates the deviation between this tool stop position and a previously taught tool stop teaching position, and calculates the deviation between the tool stop position and the tool stop teaching position taught in advance. A machining path set in advance for the surface to be machined of the workpiece is corrected, and the workpiece control means M12 processes the workpiece M6 by controlling the second motor M5 according to the correction result. That is, by correcting the machining path according to the deviation between the tool stop position read by the tool stop position reading means M10 and the tool stop teaching position taught in advance, the tool M1
Regardless of the wear of the workpiece M6, the tool M1 is always pressed against the workpiece M6 with the desired force.
can be processed with optimal torque.

The next tool stop position read by the tool stop position reading means M10 is the deceleration target position correction means M1.
3 is also input to the deceleration target position correction means M13.
Based on the deviation between the tool stop position and the tool stop teaching position, corrects the deceleration target position of the tool M1, which determines the timing at which the low speed drive means M9 switches the robot arm M4 from high speed drive to low speed drive. In other words, if the deceleration target position is kept constant,
When the tool M1 becomes shorter due to wear, the distance between the tool M1 and the reference surface during speed switching and the low speed driving time of the robot arm M4 become longer. The wear condition of the tool M1 is detected from the deviation from the stop teaching position,
By correcting the deceleration target position in this manner, the position of the tool M1 at the time of speed switching is made to be a predetermined position near the reference plane, regardless of the wear of the tool M1.

[Example] FIG. 2 shows the configuration of an embodiment of the present invention.

In the figure, 1 is a rotating brush that is an example of a tool, 2 is a first motor, that is, a tool spindle motor, provided in a tool mounting unit 9 that attaches the rotating brush 1 to the robot arm 3 side, and 3 is a tool mounting unit 9. ' is a robot arm that moves vertically in the drawing with respect to the robot body 10, 4 is a second motor provided in the robot body 10 and drives the robot arm 3, that is, a robot arm drive motor, and 5 is a control device body. It is equipped with an input/output section 51, an arithmetic control section 52, a storage section 53, a counter 54, and a driver 55, 6 is a workpiece, and 7 is the position of the robot arm 3, in other words, the direction in which the rotating brush 1 is pressed. 8 is a current detection device that detects the current of the tool spindle motor 2, and includes an ammeter 81, a comparator 82, and a signal output device 83.
9' is a tool mounting unit, 10 is the robot body, 11 is an operation panel having a start button 13, etc., and 12 is a driver that supplies power to the tool spindle motor 2 and is also connected to an ammeter 81. represents.

When performing the first machining process, for example, information on the brush length lo and the position Ps of the reference surface 9 of the workpiece 6 is sent to the control device main body 5 via the operation panel 11 with the arm positioned above the reference surface of the workpiece. An input operation is performed. Then, the arithmetic control section 52 performs each of the processes 101 to 108 in accordance with the robot operation, as shown in FIG. 3A.

First, from the data of the brush length lo and the reference surface position Ps, the tool position Po when the brush tip contacts the reference surface 9
can be calculated. The difference between this position and the position Pod that was virtually taught in advance as the tool deceleration position.
do is stored in the storage unit 53 as initial data 101. The tool position Po is obtained by subtracting the correction amount do from the teaching position Pod by the calculation control unit 52.
It is stored in the storage unit 53 as Pd1 (102).

Next, when the start button 13 of the operation panel 11 is turned on, the robot arm drive motor 4 is driven by the driver 55, the robot arm 3 extends downward, and the rotating brush 1 descends accordingly. This descending speed is high until the brush descends to the tool deceleration position Pd1 set in step 102, and thereafter is low. The rotating brush 1 is rotated by the tool spindle motor 2 being driven by the driver 12, and after reaching the reference surface of the workpiece 6, the rotating brush 1 is moved to the depths of the reference surface of the workpiece 6 while receiving a pressing force from the robot arm 3. 6
During this time, the tool spindle motor 2
The current value is detected by an ammeter 81 of the current detection device 8, and this detected value and a predetermined set value are compared by a comparator 82. When the rotating brush 1 comes into contact with the workpiece 6 and cuts deep into the workpiece 6,
As the cut progresses, the load applied to the rotating brush 1 increases, so the value detected by the ammeter 81 increases. When the detected value exceeds the set value, the output of the comparator 82 is inverted from, for example, a low level to a high level, and this inverted output sends the detected value from the signal output device 83 to the input/output section 51. A signal indicating that the value is greater than or equal to the set value is sent out.

When the arithmetic control unit 52 receives this signal, it stops the movement of the robot, and the counter 54 at that time
The robot arm position Pt1, which corresponds to the value detected by the position detector 7, is taken in through the input/output unit 51 (106), and the difference from the virtual stop position Pot taught in advance is calculated ( 105) and stored in the memory as the tool stop position correction amount dt1.

The series of processes and operations up to this point will be referred to as a search operation. Next, the robot arm 3 is raised this time and moves on to actual workpiece machining.

The workpiece machining path Pol is set so that the relative positional relationship in the pressing direction between the reference surface Ps and the virtual stop position Pot and the relative positional relationship in the pressing direction between the workpiece machining surface Pw and the workpiece machining teaching path are equal. Teach them in advance (108). That is, Pol is taught so that Ps-Pot=Pw-Pol. For this Pol, the arithmetic control unit 52 calculates a path Pl1 that is corrected by the amount of dt1 stored in the search operation (107), and uses this as the machining path to drive the robot to perform machining.

In this way, the operation in the first processing process ends.

Then, in the second and subsequent n-th machining processes, as shown in FIG. ) is performed. However, the setting of the deceleration position correction amount dn in the search operation of this machining process is automatically set by replacing and using the previous tool stop position correction amount dtn-1 (202). The processing after the search operation (steps 205 to 209 in FIG. 3B) is the same as the first time described above.

FIGS. 4A, B, and C are diagrams for explaining the above-mentioned operation.

FIG. 4A shows, on the left side of the drawing, the positional relationship between the rotating brush 1 and the workpiece 6 at the time when the rotating brush 1 descends and reaches the deceleration position during the search operation in the first machining process, On the right side of the drawing, the rotating brush 1 is connected to the main shaft motor 2 for the workpiece biting tool.
This shows the relationship between the two at the time when the current value of is equal to or higher than the set value. After this, the machining path is corrected according to the correction value dt1, and the workpiece is machined.
Processing ends.

In the figure, Ps is the position of the reference surface that is part of the workpiece processing surface, Po and Pd1 are the brush positions when the tip of the brush 1 contacts the workpiece 6, that is,
Here, the deceleration position of the brush 1 is shown. In addition, Pod is the point virtually taught at the beginning as the brush deceleration position, and there is a correction amount dn including the first time and thereafter.
Position shifted upward by (n = 0, 1, 2,...)
Brush 1 starts decelerating at Pdn (n=1, 2, . . . ). Further, Pt1 is the position where the control device 5 receives the signal from the current detector 8 and stops the brush 1. Pot is a virtually taught point as the brush stop position similar to the above-mentioned Pod, and is a position Pth (n = 1, 2, ...), brush 1 stops at the same time as the signal is sent, and at that time dtn (=
Pot-Ptn) is stored in the storage unit 53.

FIG. 4B shows the state at the same point in time as FIG. 4A during the searching operation in the second machining process.

In this process, the brush deceleration position Pd2 is a position where the first tool position correction amount dt1 is replaced with the second deceleration position correction amount d2 and the position is corrected upward by d2 for the deceleration teaching position Pod. Yes, the brush 1 decelerates at position Pd2, and then continues the same search as the first time described above.

FIG. 4C shows the same state as FIGS. 4A and 4B in the n-th (n≧3) processing. In the figure, Pdn is dn=
dtn-1, and this is the position obtained by correcting the deceleration teaching position Pod using this as the deceleration position correction amount.

As is clear from FIGS. 4A, B, and C, the deceleration position in the second and subsequent machining processes is almost the same as the contact position between the brush tip and the workpiece reference surface, so the deceleration position in the search operation starts. It can be seen that the time from when the brush tip touches the reference surface does not increase due to wear of the brush, and therefore the brush moving time can be shortened.

[Effect of the invention] As explained above, according to the invention, the tool is pressed against the reference surface before machining the workpiece, and the tool is stopped when the pressing force, that is, the machining torque of the tool with respect to the reference surface, reaches a predetermined value. Since the position is determined and the machining path is corrected based on the deviation between this tool stop position and a previously taught tool stop teaching position, the workpiece can always be machined with the optimum torque regardless of tool wear. Also, when pressing a tool against a reference surface, the tool is moved at high speed to near the reference surface, and then pressed against the reference surface at low speed, but the deceleration target position of the tool determines the timing of switching from high speed to low speed. is corrected based on the deviation between the tool stop position and the tool stop teaching position, so the tool tip position is always controlled to a predetermined position near the reference plane when changing speeds, regardless of tool wear. The time required to detect the tool stop position can be shortened, and the machining time of the workpiece can be shortened.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram to clarify the present invention, Figure 2
The figure is a block diagram of an embodiment of the present invention, Figures 3A and B are flowcharts explaining its operation, and Figures 4A, B,
C is an explanatory diagram showing the relationship between the brush and the workpiece during the search operation during each processing process. DESCRIPTION OF SYMBOLS 1... Tool, 2... First motor, 3... Robot arm, 4... Second motor, 5... Control device main body, 6... Workpiece, 7... Position detector, 8
...Current detection device, 9...Reference surface.

Claims (1)

[Claims for Utility Model Registration] A first motor that drives a tool, detects a current value of the first motor, compares the current value with a set value, and if the current value is equal to or higher than the set value. a current detection device that outputs a detection signal at a certain time; a second motor that drives the robot arm to which the tool is attached; a position detector that detects the position of the tool in the direction in which it is pressed against the workpiece; a high-speed drive means for driving the robot arm at high speed by a second motor to cause the tool to approach a reference plane of the workpiece at high speed or a reference plane parallel thereto; and by the operation of the high-speed drive means, When the position of the tool detected by the position detector reaches a preset deceleration target position in the vicinity of the reference plane, the high-speed drive of the robot arm is switched to low-speed drive, and the tool is moved to the reference plane at low speed. a low-speed drive means that presses the tool at a low speed, and when a detection signal is output from the current detection device during operation of the low-speed drive means, the operation of the low-speed drive means is stopped, and the stop position of the tool is determined from the position detector. a tool stop position reading means for reading the tool stop position, and a deviation between the tool stop position read by the tool stop position reading means and a tool stop teaching position taught in advance, and according to the deviation, the workpiece of the workpiece is machining path correction means for correcting a machining path preset for a surface; and machining control means for machining the workpiece by controlling the second motor according to the correction result of the machining path correction means. In the processing robot control device, the low-speed drive means corrects the deceleration target position at which the robot arm switches from high-speed drive to low-speed drive based on the deviation between the tool stop position and the tool stop teaching position. A processing robot control device characterized in that a deceleration target position correction means is provided.