JPS61230868A - Burr removal by robot - Google Patents

Abstract

PURPOSE:To remove burrs surely without causing escape of the tool by controlling the cutting repulsive force below a certain level, wherein the repulsive force is sensed by a three-directional sensor mount at a robot wrist. CONSTITUTION:The threshold value for the cutting repulsive force is set so as to indicate the maximum of the tool capacity, and when the cutting repulsive force exceeds this threshold value, the position of the tool 5 is returned a little, and when it becomes below the threshold, the tool 5 is so controlled as to proceed a little from its original position. That is, the cutting repulsive force ripples around the threshold up and down while a tiff burr 12 is being cut, and the tool 5 at this time will proceed with repeated returns. When a thin burr 13 is to be cut, on the other hand, the threshold is not attained, so that the tool 5 will proceed at a constant speed. This type of control allows a robot to perform burr removal in the same way that any human operator performs the corresponding work.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a deburring method in which a three-directional force detector is provided on the wrist of a deburring robot, and a work tool is attached to the tip of the deburring robot to control the force. It is.

(Prior art) Conventionally, when performing deburring work with a robot, a cast model workpiece from which burrs have been removed is positioned with respect to the robot, and the deburring process is performed using the model workpiece as a reference without operating the work tool. The work involved first teaching the robot the movement path for deburring, and then operating the work tool to actually deburr the workpiece.

In this method, the position where the model workpiece is set is the standard, but since the surface of the casting is significantly rougher than the machined surface and the reproducibility of the setting position of the workpiece is poor, the actual workpiece and the model workpiece are different. Discrepancies in position and inclination occur in three-dimensional directions.

If you perform deburring along the path of the model work without correcting such misalignment of the work, uncut burrs and
Deburring using a robot lacked stability as it sometimes cut down to the base material of the casting.

Therefore, it is conceivable to use a visual sensor or a contact sensor to detect the above-mentioned deviations in position and inclination, but the visual sensor has drawbacks such as a complicated and expensive device and a long processing time.

Further, since the contact sensor has to be attached around the working tool, there is a drawback that the posture of the working tool and the relative position with respect to the workpiece are restricted.

Further, since burrs on castings are irregular in their occurrence location, thickness, height, etc., burrs that are significantly thicker than usual may be generated in the middle of the deburring route. At that time, if the cutting reaction force was not controlled and the tool was moved according to the path of the robot, the tool would run away when the cutting reaction force exceeded a certain value, making it impossible to perform normal deburring.

[Problem that the invention seeks to solve]

An object of the present invention is to solve the conventional problem that a tool runs away from a burr that is thicker than usual and cannot be removed during a deburring path.

[Means for solving problems]

In deburring work in which a work tool is attached to a robot equipped with a three-directional force detector on its wrist, the present invention aims to change the position of the tool slightly when the reaction force due to cutting received from the work tool exceeds a certain value. This solves the problems of the conventional method by moving the tool forward again to remove burrs when the value falls below a certain value.

〔Example〕

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

First, a description will be given of a deburring method in which a three-directional force detector is provided on the wrist of a deburring robot, and a work tool is attached to the tip of the deburring robot to control the force.

FIG. 2 ((a) is a side view, and the peaks are a front view) shows an example of the embodiment, and the wrist 2 of the robot 1 is marked with an X.

A force detector 3 capable of detecting force in three directions of Y and Z is fixed,
A deburring tool 4 driven by an electric motor or an air motor is fixed to the force detector 3. Work tool 4
A tool 5 selected according to the material and shape of the workpiece, the size and shape of the burr, etc. is attached to the tool.

A model workpiece 6 from which burrs have been completely removed in advance is fixed to the workpiece set table 15 at an appropriate position relative to the robot l.

The robot 1 approaches the model workpiece 6 from the X direction at a relatively low speed without rotating the tool 5 attached to the work tool, the tool 5 and the model workpiece 6 come into contact, and the X direction output of the force detector 3 is When a certain value is exceeded, it is recognized that the two have contacted each other, and the robot control panel stores the coordinate value in the X direction at that time. Y in a similar way.

By recognizing and storing the coordinate values of the model workpiece in the Z direction, the three-dimensional relative positions of the robot 1 and the model workpiece 6 are determined.

After that, the robot is taught the deburring route based on the model work.

A case where the model work and the actual work are deviated in parallel is shown in Figure 3 ((a) is a side view, (bl is a front view).The actual work 7 is on the work setting table 15 and is different from the model work. Fixed in position.

Then, the coordinate values of the model work 7 mentioned above are determined, and by comparing them with the coordinate values of the model work, the deviation amount δ8 is determined. δ1.
Since δ2 is calculated, the relative position of the actual workpiece 7 of the robot 1 is determined. Therefore, the number of robot paths taught for the model work is δ, δ9. By shifting by δ2, an ideal deburring path can be obtained for the actual workpiece.

Figure 4 shows the case where the model work and the actual work are tilted in the longitudinal direction ((a) is a side view, (bl is a front view)
Shown below.

An actual workpiece 8 is fixed on a workpiece set table 15 with its longitudinal direction inclined relative to the model workpiece. Therefore, the coordinate values in the Z direction at positions A and B are recognized using a method similar to the coordinate recognition of the model workpiece described above, and if the difference between them is l, then the inclination θ2 in the longitudinal direction of the actual workpiece is 5in-'θz=
Determined by 1/L. Therefore, by tilting the robot path taught for the model workpiece by θ2, an ideal deburring path for the actual workpiece can be obtained.

Similarly, the inclination in the X and Y directions is θ8. Since θ can also be calculated, the robot's route can be corrected.

Through the above operations, it was found that deburring work could be done in an ideal path even if the workpiece was fixed at a different position than the model workpiece or at an inclined position.Then, by rotating the tool attached to the work tool, A detailed explanation of the present invention in a deburring operation is shown in FIG.

A-1 (front view) and A-2 (top view) in Fig. 1 show that the workpiece 10 with burrs 12 and 13 on the wooden mold mating surface 11 is fixed to the robot 1, and the model workpiece and This figure shows the deburring work to be performed after correcting the position and inclination deviation of go. Since the burrs 12 and 13 that are generated on the way have different thicknesses and 'r+ > Tt,
It is expected that a large cutting reaction force will be applied to the tool when cutting the burr 12. Therefore, it is necessary to set a threshold value for the cutting reaction force, which indicates the maximum value of the cutting ability of the tool, and to control the cutting reaction force so that it does not exceed the threshold value.

In order to achieve this purpose, when the cutting reaction force exceeds a threshold value, the tool position is moved back a little, and when it falls below the threshold value, the tool is moved forward a little further from the original position. As shown in Figure (B), when cutting a thick burr 12, the magnitude of the cutting reaction force repeatedly rises and falls around the threshold value, but when cutting a thin burr 13, the cutting reaction force does not reach the threshold value. So, continue cutting. The relationship between the tool position and time at this time is shown in FIG. 1(C). Bali 12
When cutting, the tool moves back and forth, causing burrs.
When cutting No. 3, the cutting progresses only at a constant speed.

By performing the above-mentioned control, it is possible to realize a deburring work by a robot that is very similar to a deburring work performed by a human holding a deburring work tool in hand.

〔Effect of the invention〕

As described above, according to the present invention, by performing control to suppress the cutting reaction force detected by the three-directional force detector provided at the robot's wrist to a certain value or less, the tool can be reliably burred without running away. can be removed.

Therefore, since it is not necessary to check whether burrs have been removed after deburring, the deburring time per workpiece can be shortened.

[Brief explanation of the drawing]

FIGS. 1 to 4 are explanatory diagrams each showing an embodiment of the deburring method according to the present invention. 1: Robot 2: Wrist 3: 3-directional force detector 4: Deburring tool 5: Tool 6: Model work 7. 8: Actual work 10: Work 11: Wooden pattern mating surface 12. 13: Burr 14: Tool Route 15: Work set table

Claims (1)

[Claims] In deburring work, in which a work tool is attached to a robot equipped with a 1-, 3-way force detector on its wrist, when the reaction force due to cutting received from the work tool exceeds a certain value, the tool is slightly returned to its position and A deburring method using a deburring robot characterized in that when the value falls below the value, the tool is moved forward again to remove the burr.