JPH0719711Y2 - Position correction device for automatic grinding machine - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application The present invention relates to a position correction device for an automatic grinding machine which is configured by attaching a grinder to a robot.

B. Outline of the Invention The present invention is a position correction device for an automatic grinding device formed by attaching a grinder having a disk-shaped grindstone that rotates at the tip of a robot arm, and a sensor body for measuring the wear amount of the grindstone. , An illumination device and an image pickup device, which are arranged to face each other in a direction parallel to the plate surface of the grindstone, and an image memory device and an image processing device for fetching an output signal of the image pickup device.

That is, the position correction device of the present invention measures the wear amount by comparing (comparing with the already stored value) images in the direction parallel to the plate surface of the grindstone (side surface image of the grindstone). It outputs a signal to correct the position of the robot based on it, and as a result, the wear amount of the grindstone is measured accurately,
This is to enable accurate correction of the working point of the automatic grinding machine.

C. Conventional technology When performing deburring work on a robot arm with a grinder having a rotating disk-shaped grindstone, the robot performs repetitive work as taught in advance. It is generally practiced to control the back system. However, with the progress of deburring work, the grinder's grindstone wears, and the work point of the grinder shifts by the amount of wear of this grindstone, resulting in variations in the finished dimensions of the work and unburred uncut parts. There is.

For this reason, conventionally, the wear amount of the grindstone is measured at a constant work process and time set by the operator, and the deviation of the working point due to the wear of the grindstone is corrected. For example, Japanese Utility Model Laid-Open No. 62-130866 is known as a means for correcting the working position of a robot due to the abrasion of this kind of grindstone.

A conventional device of this type will be described in detail with reference to FIG.
Reference numeral 1 denotes a robot having a plurality of arms rotatably connected to each other, and an arm tip 1a of the robot 1 is provided with a grinder 2. Reference numeral 3 denotes a rotating disc-shaped grindstone, which is driven to rotate by a motor in the main body of the grinder 2 and removes burrs generated on the work 4 fixed to the fixing jig.

A sensor body 5 for measuring the outer peripheral position (tip position) of the grindstone 3 is provided at a predetermined position within the rotation range of the robot 1. This sensor body 5 has a main body 6 formed in a U shape.
The light emitting device 7 and the light receiving device 8 are provided in the opposite sides of the opening of the main body 6 facing each other, and the control device 9. In addition, 10 is a power supply device.

Next, the position correction of the robot in the automatic grinding apparatus configured as described above, that is, the position correction of the grindstone 3 will be described. After performing deburring work set in advance, the grindstone 3 included in the grinder 2 is moved into the sensor body 5, and the outer peripheral position (tip position) of the grindstone 3 is detected.

Since the preset work is set according to the type of the work, the worker knows in advance the cycle of the deburring work until the work point needs to be corrected due to the abrasion of the grindstone 3. I need to put it. The detection of the tip position of the grindstone 3 is carried out by moving the robot 1 toward the sensor body 5 from a preset reference point. At this time, the tip processed surface 3a of the grindstone 3 of the grinder 2 is the light projector of the sensor body 5. This is performed while keeping the posture parallel to the optical axis of 7 and at a constant moving speed. Then, the tip of the grindstone 3 blocks the optical axis of the sensor body 5 to detect the position of the tip of the grindstone 3, sends a signal to the controller 9, and the robot 1 stops.

The controller 9 compares the vector from the reference position to the tip position of the grindstone 3 detected with the vector from the reference position to the tip position of the grindstone 3 detected before the deburring operation to determine the wear amount of the grindstone 3. Measured, based on this wear amount, a correction amount is calculated so that the working point of the grindstone 3 matches the working point of the grindstone 3 before wear, and the operation command of the robot 1 is corrected, and the deburring work is restarted again. Is. In the position correction of the grindstone 3 described above, the wear amount of the grindstone 3 is measured without stopping the grinder 2 (without stopping the rotation of the grindstone 3), and the work point for deburring by the grinder 2 can be corrected. I have to.

D. Problems to be Solved by the Invention As described above, the position correction device of the conventional automatic grinding device compares the vector value obtained by the encoder or the like provided on each axis of the robot with the previous vector value. The wear amount of the grindstone is measured, and the working point of the robot is corrected based on this wear amount.

That is, since the amount of wear of the grindstone is measured by comparing the postures of the robot itself, there are the following problems.

(A) The conventional method of measuring the wear amount of a grindstone is to measure the end surface of the grindstone.
Since it is performed so that 3a is kept parallel to the optical axis of the sensor body 5, for example, as shown in FIGS. 4 (a) and 4 (b), when the tip processed surface 3a is worn in an inclined manner, etc. In this case, it is necessary to change the posture of the grinder 2, that is, the posture of the wrist of the robot 1, so that the tip processed surface 3a inclined each time becomes parallel to the optical axis of the sensor body 5. Therefore, the work is troublesome, and there is a problem that an error occurs in the measured value of the wear amount of the grindstone unless the inclination of the tip processed surface 3a can be accurately measured.

(B) At the time of grinding work, the tip processed surface 3a of the grindstone 3 may be inclined and worn depending on the position of the burr generated on the work, the size of the burr, and the like. It is not possible to keep 3a and the optical axis of the sensor body 5 parallel to each other. Therefore, an error occurs in the measured value of the amount of wear of the grindstone, and since the end surface of the grindstone cannot be identified, problems such as excessive burring and uncut burring occur.

(C) The robot has a slight error in its operation due to backlash and thermal expansion of each power transmission mechanism, and this error causes an error in the wear amount of the grindstone to be measured. That is, since the wear amount of the grindstone 3 is detected in a posture state of the robot different from that at the time of grinding, the error due to the robot self-confidence causes an error in the measurement of the wear amount of the grindstone. Since the amount of wear was not accurately measured in the new work, there was a problem that in the subsequent grinding work, there were variations in the finished size of the work, and the uncut portion exceeded the allowable range.

(D) The tip position of the grindstone 3 is detected by the sensor body 5 which detects the tip of the grindstone 3 and sends this signal to the control device 9 to detect the position of the robot 1 at this time. The signal 5 causes a delay before the robot 1 stops, resulting in an error in the measurement result of the posture position of the robot.

(E) When the grindstone is abnormally worn during the preset work, the robot 1 and the grinder 2 come into contact with the sensor body 5 when the grindstone 3 is brought close to the sensor body 5 for measurement. Then, robot 1, grinder 2, grindstone 3,
In some cases, the sensor body 5 was damaged.

E. Means for Solving the Problems The present invention is a position correction device for an automatic grinding device formed by attaching a grinder having a disk-shaped grindstone rotating at the tip position of a robot arm, and measures the wear amount of the grindstone. The sensor body is composed of an illuminating device and an image pickup device, which are arranged to face each other in a direction parallel to the plate surface of the grindstone, and an image memory device and an image processing device for fetching an output signal of the image pickup device are provided to provide the grindstone. The position correction device of the automatic grinding device is configured to accurately measure the wear amount of the.

F. Action The position correction device of the present invention measures the amount of wear by comparing (comparing with the already stored value) images in the direction parallel to the plate surface of the grindstone (side surface image of the grindstone). Since it outputs a signal that corrects the robot position based on the above, it is possible to set the robot stop position at the time of wear amount measurement as a fixed position, and as a result, the wear amount of the grindstone can be measured accurately and automatic grinding is performed. The working point of the device can be accurately corrected.

G. Embodiment The present invention will be described based on an embodiment shown in FIGS. 1 and 2. It is to be noted that the components denoted by the same reference numerals as those in FIG. 3 described above are the equivalent products, and thus detailed description thereof will be omitted.

A sensor body 20 for detecting the wear amount of the grindstone 3 is provided at a predetermined position in the work space of the robot 1. This sensor body
Reference numeral 20 denotes a box-shaped main body 21, an illuminating device (parallel light projector including a light source and a lens) 22 provided on both sides of the opening 21a facing each other of the main body 21, and facing each other.
Imaging device (consisting of TV camera, image sensor, etc.) 23
It consists of and. The opening 21 a of the main body 21 is installed toward the robot 1.

In the main body 21 of this sensor body 20, the grindstone 3 from the opening 21a.
The image of the side surface of the grindstone 3 is taken by inserting the.

A range indicated by a chain double-dashed line in FIG. 2 indicates an image capturing range of the image pickup device 23, and it is desirable that the range on the side surface of the grindstone 3 covers at least the use limit of the grindstone 3.

The output end of the sensor body 20 is connected to the image memory device 2
4. Connected to the robot controller 9 via the image processor 25. The image memory device 24 and the image processing device 25 for processing the signal from the image pickup device 23 store the image signal of the advance (initial value, previous work) detected by the image pickup device 23,
Then, it also has a function of performing a comparison calculation of the stored image signal and the image signal detected after the work to calculate the wear amount of the grindstone 3. 26 is a measurement standard setting unit, and this measurement standard setting unit 26 is a bearing in the main body 21 of the sensor body 20.
A rod 28 slidably supported by 27 and having one end side (the left side in FIG. 2) penetrating the main body 21 and protruding toward the robot 1 side, and an image captured by the imaging device 23 in the main body 21. A transparent scale 29 located within the range and fixed to the rod 28, a spring 30 mounted on the rod 28 so as to urge the rod 28 to the side opposite to the robot, and an end portion (inner end) of the rod 28. And a limit switch 31 which is engaged.

The output of the limit switch 31 is connected to the control device 9 of the robot 1 and is programmed so that the robot 1 will make an emergency stop when the limit switch 31 is turned on.

It should be noted that the grinder 2 is provided with a position mark 32 with which the tip of the rod 28 of the measurement reference setting portion 26 abuts when the wear amount of the grindstone 3 is measured, and the rod 28 also has a position mark 33.
Is provided. Reference numeral 33 is a monitor TV used for setting and adjustment.

Next, the position correction of the robot 1 in the automatic grinding apparatus configured as described above, that is, the measurement of the wear amount of the grindstone 3 will be described. When measuring the wear amount of the grindstone 3 after performing a preset deburring operation, the robot 1 is moved in the direction of the sensor body 20 to a predetermined position set in advance. The wear amount measurement position of the grindstone 3 is an opening in the main body 21 of the sensor body 20 with the grindstone 3 in the horizontal state.
It is inserted from 21a, and is a position between the illumination device 22 and the imaging device 23, and the imaging device 23 can photograph the side surface of the grindstone 3.
Moreover, the tip of the grinder 2 presses the rod 28 provided on the sensor body 20, the rod 28 moves slightly to the right in the drawing, and the position mark 33 provided on the rod 28 is the same as the wall surface of the main body 21. The amount of pushing of the rod 28, that is, the stop position of the robot 1 is preset and taught to the robot 1.

The side surface of the grindstone 3 is photographed by the image pickup device 23 at the position where the robot 1 is stopped, and the image signal thereof is stored in the image memory device 24.
Also, the abrasion amount of the grindstone 3 is calculated by inputting the same to the image processing device 25 and performing a comparison calculation with the image data stored by the previous processing (initial value, data of the previous work). Based on this wear amount, the control device 9 of the robot 1 corrects a new work point of the robot 1.

If the measurement reference setting unit 26 is provided as in the embodiment, it is easier than the case where the correction processing of various errors is not provided. That is, since the grinder 2 is provided with the rod 28 that can move forward and backward by contacting the grinder 2 and the position marks 32 and 33 are provided on the predetermined members, the error of the positional deviation can be easily visually recognized.

Especially when there is an error in the horizontal direction, the grinder 2 abuts on the rod 28 and pushes the rod 28, so that the relative positional relationship between the grindstone 3 and the transparent scale 29 does not change. Therefore, comparison calculation of images before and after work can be easily performed.

If the robot arm 1a pushes the rod 28 due to over-movement from the preset wear amount measurement position (robot stop position) due to a failure of the robot 1, the rod 28 End of the limit switch 31
Since the robot is turned on, the robot 1 is stopped urgently and the damage to the sensor body 20 can be minimized.

Therefore, these processes can be performed by the image processing device 25 without the measurement reference setting unit 26.

For example, the error in the vertical direction can be solved by the image processing device 25 so that the vertical positions of the images of the grindstone 3 before and after the work are matched.

H. Effect of the Invention The position correcting device according to the present invention comprises an illuminating device and an image pickup device, which are arranged so that the sensor body is opposed to each other in a direction parallel to the plate surface of the grindstone, and the output signal of the image pickup device is provided. Since the image memory device and the image processing device for taking in are included, it is possible to measure the amount of wear by comparing and calculating the images of the side surfaces of the grindstone.

Therefore, even if the tip processed surface of the grindstone is inclined, even if the inclination state of the tip processed surface changes, the wear amount of the grindstone can be accurately measured without changing the posture of the robot as before. be able to.

Since the amount of wear of the grindstone is measured by an image taken after stopping the robot, an error does not occur in the measured value due to the delay of control.

The error caused by the mechanism of the robot itself does not adversely affect the measurement of the wear amount, and the wear amount of the grindstone can be accurately measured.

In the new work after the correction, burrs and the like can be surely ground and removed, so that problems such as variations in the finished size of the work and uncut portions exceeding the allowable range can be solved.

When measuring the amount of wear on the grindstone, the robot stop position can be set to a preset fixed position, so there is no delay in stopping the robot during measurement, and the robot position during result measurement is not delayed. The problem that the posture causes an error in the measurement result is eliminated.

Even if the grindstone is abnormally worn during the preset work, the robot stop position can be set, so the robot 1 and grinder 2 come into contact with the sensor body 20 and the robot 1 and grinder 2 It is possible to prevent the grinding wheel 3, and the sensor body 20 from being damaged.

[Brief description of drawings]

FIG. 1 is an explanatory view of an automatic grinding device equipped with a position correcting device according to the present invention, FIG. 2 is an explanatory view of a main part of the position correcting device according to the present invention, and FIG. 3 is an automatic grinding device equipped with a conventional position correcting device. FIGS. 4 (a) and 4 (b) are explanatory views of the apparatus, and are explanatory views when a wear amount of a grindstone is measured in a conventional position correction apparatus. 1 ... Robot, 2 ... Grinder, 3 ... Grindstone, 20 ...
… Sensor body, 21 …… Main body, 22 …… Illumination device, 23 …… Imaging device, 24 …… Image memory device, 25 …… Image processing device.

Claims (1)

[Scope of utility model registration request] 1. A sensor body for detecting the tip position of the grindstone and an output end of the sensor body in an automatic grinding machine formed by attaching a grinder having a rotating disk-shaped grindstone to the tip of a robot arm. In a position correction device including a robot control device, the sensor body is composed of an illuminating device and an imaging device that are provided to face each other in a direction parallel to the plate surface of the grindstone, and an output signal of the imaging device. And a sensor provided with an image memory device and an image processing device for loading the sensor, the rod being slidably supported by a bearing provided in the sensor body, the rod penetrating the sensor body and protruding toward the robot, and the sensor. The scale, which is located in the image capturing range of the imaging device inside the body and is fixed to the rod, and the rod that is urged toward the anti-robot side are attached to the rod. 1. A position correction device for an automatic grinding machine, comprising a measurement reference setting part including a suspended spring and a limit switch with which an end of a rod engages.