JPH0357411Y2 - - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application The present invention relates to a device that uses a robot to automatically follow and grind parts to be ground that protrude from a base material, such as burrs on a cast product.

B. Overview of the invention The present invention is an automatic grinding device using a robot, in which a scanning device is installed on the robot so that the movable part relative to the robot scans left and right in the direction of tool movement, a distance sensor is directed toward the part to be ground, and a distance sensor is directed toward the grinding tool. By installing the distance sensor in the moving part of the scanning device at the front in the direction of movement, the distance sensor scans left and right in the direction of tool movement independently of the movement of the robot, and the position and size of the part to be ground can be determined from the distance signal from this distance sensor. By determining the height and controlling the robot, grinding is performed with an appropriate depth of cut while following the part to be ground.

C. Prior Art When producing cast iron products, it is necessary to remove the thin fin-like cast burrs that are formed when hot water flows into the joints of the molds, and the bulges that are inevitably formed due to gas venting in the molds. is necessary. When mass producing the same type of cast iron products, such deburring work has conventionally been carried out by automatic grinding using a robot in order to improve work efficiency. Generally, a grinding tool is installed in a so-called teaching playback type robot that automatically repeats a procedure once operated by an operator, and when the robot operates, the grinding tool is used to remove burrs protruding from the surface of the base material of a cast product. This burr is removed by grinding while moving it to follow the direction.

D. Problems that the invention aims to solve However, when a robot deburrs castings, there are dimensional errors in the finish between the castings and errors in the positioning of the workpiece, so these need to be corrected. In particular, in the teaching playback method, which is the mainstream method of deburring, positioning accuracy has traditionally been improved as much as possible, but it ignores variations between workpieces and the fact that the size and height of burrs are not constant. Therefore, when using a robot that uses only the teaching playback method, the positioning accuracy and finishing errors between workpieces directly affect the grinding accuracy. In order to improve grinding accuracy, it is necessary to increase positioning accuracy and reduce dimensional errors between individual castings, but the positioning equipment is extremely expensive, and the nature of the castings limits product accuracy, making it difficult to put into practical use. Not on target. As a result, the product becomes defective and rework is required. Furthermore, since the size and height of the burr are not constant, the robot must be moved to assume the maximum burr and start grinding from there, resulting in wasted time and reduced work efficiency.

In view of the problems of the prior art described above, the present invention provides an automatic grinding device that can accurately follow and grind the part to be ground without being affected by workpiece positioning accuracy or dimensional errors between workpieces. The purpose is to

E. Means for Solving the Problems The automatic grinding device according to the present invention that achieves the above-mentioned purpose has a robot equipped with a grinding tool, and when the robot operates, the grinding tool follows the part to be ground that protrudes from the base material and performs grinding. In an automatic grinding device, the scanning device has a movable part relative to the robot, the fixed part is provided on a fixed part of the grinding tool, and the movable part scans left and right in a tool traveling direction perpendicular to the height direction of the part to be ground. and a distance sensor provided on the movable part of the scanning device, oriented toward the part to be ground and located in front of the progress direction of the grinding tool, and the position and size of the part to be ground obtained from the distance signal of the distance sensor. and a control device that controls the robot based on information on height and height.

F. Effect A distance sensor is placed in front of the grinding tool in the direction of movement, and is provided on the movable part of the scanning device that scans left and right, rather than on the movement of the robot itself. As a result, the distance sensor scans left and right in the tool traveling direction independently of the progress of the grinding tool by the robot, and the distance signal of the distance sensor changes depending on the protruding shape of the part to be ground relative to the base material. Therefore, even if there is a positioning error of the workpieces and a dimensional error between the workpieces, the position, size, and height of the part to be ground can be accurately determined from the distance signal.
Therefore, by controlling the robot based on the determined position, size, and height, it is possible to accurately follow the part to be ground and grind it with an appropriate depth of cut.

G. Example An example of the present invention is shown in FIGS. 1 to 3.

As shown in the front view of Fig. 1 and the side view of Fig. 2, an optical distance sensor 2 is provided at the front upper part of the grinder 1 as a grinding tool in the forward direction of movement, and the optical distance sensor 2 is scanned left and right by a linear motor. I'm starting to do that. 3 is the stator of the linear motor,
The optical distance sensor 2 is provided with a movable winding.
A grinder 1 is attached to a robot, and a stator 3 of a linear motor is attached to a fixed portion of the grinder 1. The optical distance sensor 2 is directed toward the part to be ground 4a. In addition, optical distance sensor 2
Instead, various distance sensors such as ultrasonic distance sensors, capacitance distance sensors, and electromagnetic distance sensors can be used. Also, instead of a linear motor, various types of scanning devices can be used, such as cylinders or other motorized ones. In the figure, 1a is a grindstone, and 4 is a base material.

As shown in FIG. 3, the grinder 1 is attached to the tip of the arm of the robot 5. This robot 5 is of a teaching playback type. Reference numeral 6 denotes a control device main body of the robot, of which a portion 7 surrounded by a two-dot chain line forms a part. A grinder current detection sensor 9 is provided between the grinder 1 and its power source 8, and a grinder current detection signal is taken into a microcomputer 11 through an A/D converter 10. Further, the distance signal from the optical distance sensor 2 is also taken into the microcomputer 11 through the A/D converter 10. Furthermore, the set value signal of the grinder current setting device 12 is also taken into the microcomputer 11 through the A/D converter 10. 13
is the interface.

The operation of the automatic grinding apparatus shown in FIGS. 1 to 3 will be explained.

First, the robot 5 is taught in advance the grinding trajectory and the grinding completion position, even if it is rough. Also, set the grinder current. Further, the scanning center point of the optical distance sensor 2 is determined, for example, at a position exactly in front of the grinder 1, which is the center of grinding. In this state, the robot 5 is operated to start automatic grinding. Grinding may be done only once, or may be repeated several times.

Now, suppose that the taught grinding locus and the actual part to be ground 4a of the workpiece deviate from each other due to a positioning error of the workpieces or a dimensional error between the workpieces. The mask computer 11 determines the center position of the part to be ground 4a from the change in distance signal due to scanning, and gives a command for the grinding path to the control device main body 6 so that the center of grinding is located at this position. This ensures that a correct grinding trajectory is always obtained.

It is also assumed that there is variation in the height of the part to be ground 4a. The microcomputer 11 also calculates the height from the change in the distance signal and sends it to the control device main body 6.
instruct. This provides an appropriate depth of cut. Furthermore, the microcomputer 11 determines the distance L _p between the optical distance sensor 2 and the grinding point of the grinding wheel 1a, and the distance L w between the optical distance sensor 2 and the base material 4 near the part to be ground 4a, from the distance signal, and calculates L _{w .} A command is given to the control device main body 6 so that = L _p . Thereby, only the part to be ground 4a is ground, and the depth of cut is adjusted to an appropriate amount so that the base material 4 is not cut.

On the other hand, the robot 5 controls the depth of cut so that the grinder current is at or below the set value. This is because if the amount of cut is too large and cuts into the base material 4, the clinder current will increase, so this is detected and the cut into the base material 4 is prevented. However, if there is variation in the size (width) W of the part to be ground 4a, if W is large, it may be mistaken as a cut into the base material 4. On the other hand, the microcomputer 11 determines the size of the part to be ground 4a based on the change in the distance signal, corrects the grinder current setting value according to this size, etc., and causes the control device main body 6 to cut into the base material 4. The presence or absence of such information is commanded. This reduces grinding time.

In the embodiment described above, when teaching the grinding trajectory, even if there is a slight deviation, the deviation is measured and automatically corrected while scanning the distance sensor. This enables rough teaching and simplifies the teaching work.

Automatically corrects dimensional errors between workpieces,
Since the grinding tool always grinds at the same position (in front of the tool) and moves along the optimal trajectory, there is no need to reteach each product or problems such as finishing errors that were conventional.

Since the positioning of the workpiece can be performed roughly, the positioning device becomes inexpensive. Further, if the displacement of the workpiece is not too large, a positioning device is not necessary.

In addition, work efficiency is high because the trajectory is corrected during grinding.

Furthermore, compared to robots with only teaching playback, the finishing accuracy is higher, and product defects and rework work are drastically reduced.

Grinding time is shortened because grinding is always done with the optimum depth of depth.

In order to control so that L _w = L _p , ○A When teaching the grinding completion position, the grinding completion is automatically detected even if the position is slightly off, making rough teaching possible and making the teaching work easier. .

○B) Since the completion of grinding is automatically detected even for dimensional errors between workpieces, there is no need to reteach each product and finish problems such as over-cutting or uncut parts, which were required in the past.

○C Since grinding completion is confirmed while grinding, there is no problem with grinding ability.

○D There is no uncut material or over-cutting, reducing product defects and improving reliability.

H. Effect of the invention According to the invention, it is possible to accurately follow and grind the part to be ground without being affected by the positioning accuracy of the workpieces or the dimensional error between the workpieces. In particular, since the distance sensor is moved relative to the robot by the scanning device, the distance sensor can scan left and right in the tool advancing direction independently of the robot's grinding operation even during grinding. The robot can be controlled by obtaining information about the robot.

[Brief explanation of the drawing]

FIG. 1 is a front view of the distance sensor installation part, FIG. 2 is a side view thereof, and FIG. 3 is a diagram of the overall configuration. In the drawing, 1 is a grinder, 1a is a grindstone, 2 is an optical distance sensor, 3 is a linear motor stator, 4 is a base material, 4a is a part to be ground, 5 is a robot, 6 is a control device main body, and 8 is a grinder power supply , 9 is a grinder current detection sensor, 10 is an A/D converter, 11 is a microcomputer, 12 is a grinder current setting device, and 13 is an interface.

Claims (1)

[Scope of Claim for Utility Model Registration] (a) In an automatic grinding device in which a robot is equipped with a grinding tool and the grinding tool follows a part to be ground protruding from a base material by the operation of the robot, (b) the above-mentioned robot (c) a scanning device having a movable part for the grinding tool, the fixed part being provided at a fixed part of the grinding tool, and the movable part scanning left and right in a tool advancing direction perpendicular to the height direction of the part to be ground; (d) a distance sensor provided on the movable part of the scanning device, oriented toward the grinding part and located in front of the grinding tool in the traveling direction; (d) the position and size of the part to be ground obtained from the distance sensor distance signal; An automatic grinding device comprising: a control device that controls the robot based on height information.