JPH0243659Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a grinding overload prevention device and is intended to prevent damage to a grinder.

<Conventional technology> Currently, industrial robots are widely used in factories, etc., and deburring work from castings, which used to rely on the skill and hard labor of workers, has come to be performed by industrial robots. ing. In order to remove burrs efficiently, it is necessary to keep the grinder attached to the arm of the industrial robot constantly rotating at high speed. Therefore, adaptive control is performed in which the arm feed speed is increased when the burr is small, and conversely, when the burr is large, the arm feed speed is slowed down to prevent the rotational speed from decreasing due to grinding resistance. In other words, as shown in FIG. 3, the grinder 2 attached to the arm 1a of the industrial robot 1
When grinding the burr 3a of the grinding work 3, the current sensor 5 detects the grinder current supplied from the grinder power source 4 to the grinder 2, and this detected value is sent to the microcomputer 7 via the A/D converter 6. The microcomputer 7 compares the detected value with the set value, and the robot controller 8 controls the robot 1 so that the two match. Since the feed speed of the arm 1a is thus controlled so that the grinder current is constant, the grinder 2 can always exhibit its maximum grinding ability.

<Problems to be Solved by the Invention> By the way, in the above-mentioned conventional technology, there was a delay in the above-mentioned adaptive control due to the response delay of the robot controller 8. For this reason, if a large burr suddenly appears, the adaptive control will not be able to keep up with it, and the rotational speed of the grinder 2 will decrease due to grinding resistance, reducing grinding efficiency. Furthermore, the grinding wheel of the grinder will become stuck in the burr and be damaged. It was hot.

Therefore, in view of the above-mentioned drawbacks, the present invention provides a grinding overload prevention device that maximizes the grinding capacity of the grinder to improve the grinding capacity, and prevents the grinding wheel from digging in and causing damage. With the goal.

<Means for Solving the Problems> The outline of the present invention for achieving the above object is that a movement mechanism for moving the grinding tool in the advancing direction of the arm and in the opposite direction is added to the hand section, and a movement mechanism is added to the hand section, which is separate from the robot controller. The circuit includes a servo mechanism that moves the moving mechanism by a motor in response to the drive current, and a hand that detects at least the end of the movement of the moving mechanism and controls the robot controller, and detects overload. When the drive current increases, the servo mechanism is moved continuously to reduce the load on the grinding tool using the moving mechanism.

<Example> Here, an example of the present invention will be described with reference to FIGS. 1 and 2. In FIG. 1, a current sensor 5 that detects a drive current from a grinder power supply 4 to a grinder 2, which is a grinding tool, is connected to an A/D converter 6 together with a grinder current setting device, and then to a microcomputer 7. and
By this microcomputer 7, the grinder 2
The drive current is compared to see if there is a difference from the value set by the setting device.

When the drive current of the grinder 2 is larger than the set value, the grinding load is large, so the microcomputer outputs a signal to the robot controller 8 via the DI/DO 9 to reduce the advancing speed of the arm 1a. When the drive current is smaller than the set value, the grinding load is small, so the microcomputer 7 outputs a signal to the robot controller to increase the advancing speed of the arm 1a.

Now, the microcomputer 7 passes through the amplification stage 10 of the motor driver to the moving mechanism 1 attached to the hand section at the tip of the arm 1a of the industrial robot 1.
1 motor (see FIG. 2) to form a servo circuit. Further, a limit switch (see FIG. 2) for detecting the start and end ends of movement of the moving mechanism 11 is connected to the DI/DO 9.

When the drive current of the grinder 2 is different from the set value, the motor is driven by a signal from the microcomputer 7 according to the difference, and moves the moving mechanism 11. In addition, the limit switch is the moving mechanism 11.
DI/
Inputting to DO9.

The tip of the arm 1a of the industrial robot 1 is connected to the second
As shown in the figure. A moving mechanism 11 is connected to the hand portion at the tip of the arm 1a via an auto tool chainer 12.
is installed. This moving mechanism 11 includes a slide mechanism 11a in which a locking part moves on a rail, a drive mechanism 11b consisting of a rack arranged along the slide mechanism 11a and a pinion that meshes with this rack, and a part of a servo mechanism. Drive mechanism 1
It consists of a motor 11C such as a DC servo motor or a stepping motor that drives the pinion 1b, and a limit switch 11d that detects the start and end of the slide of the slide mechanism 11a. The sliding direction of the sliding mechanism 11a is made to coincide with the advancing direction and the opposite direction of the arm 1a.

The grinder 2 having the grindstone 2a is attached to the slide side of the slide mechanism 11a.
Therefore, the grinder 2 is moved by the advancement of the arm 1a of the industrial robot 1, and also by the drive of the motor 11c of the moving mechanism 11.
It can move in the direction of travel and in the opposite direction. However, under normal load conditions in which the arm 1a is moved to grind away the burr 3a, the slide mechanism 1 in the figure
1a is always located on the leftmost side (on the traveling direction side). If the slide mechanism 11a moves to the right (in the direction opposite to the direction of movement of the arm) due to the drive of the motor 11c, it is when a command signal from the microcomputer 7 is input, and the drive current of the grinder greatly exceeds the set value. It's time. That is,
This is when the grinding load is increasing. Further, even if the slide mechanism 11a is moved to the right by the motor 11c, it returns to the left when the drive current of the grinder becomes less than the set value. The signal from the limit switch 11d detects the end of the slide mechanism 11a when there is an overload even if the slide mechanism 11a moves due to a large load due to burrs, and this detection signal reaches the DI/DO9 and is used for industrial purposes. This is to bring the robot to an emergency stop.

The operation when performing grinding work for deburring is as follows. To remove burrs from the grinding workpiece 3 by driving the grinder 2 attached to the tip of the arm 1a, the arm 1a is moved along the burr. At this time, in a normal load state, the grinder drive current is detected and a normal advancing speed command is sent from the robot controller 8 to the robot 1. Also,
In a light load state, the robot controller 8 issues a high-speed advancing speed command according to the load by detecting the grinder drive current.

On the other hand, when the grindstone 2a collides with a large burr and the load increases, the robot controller 8 issues a command to the robot 1 to slow down the advancing speed of the arm 1a in accordance with the load. In this case, when the load is large and the drive current exceeds the measured value, the microcomputer 7 issues a drive command to the motor 11c of the moving mechanism 11 at the same time as the robot controller 8 controls, and the motor 11c causes the slide mechanism 1 to move.
1a moves, and the grindstone 29 escapes in a direction opposite to the advancing direction of arm 1a. This robot controller 8
The motor 11c is driven without interruption when there is an overload, and the grinder 2 instantly escapes. Then, when the robot controller 8 issues a slow speed command, the advancing speed of the arm 1a becomes very slow and the drive current decreases, and the slide mechanism 11a returns to its initial state in accordance with the current value. If a command to drive the motor 11c is issued again even after the slide mechanism 11a reaches its terminal end, an emergency stop command for the robot 1 is issued by the limit switch 11d.

In this way, the grinder 2 will first retreat in the event of a sudden overload due to burrs, so even if the response of the arm 1a becomes slow, the grinding wheel will not be damaged or the speed of the grinder 2 will not decrease.

<Effects of the invention> As explained above, according to the invention, an emergency evacuation function or an emergency stop function is added to the grinder, so that the maximum grinding capacity of the grinder is fully utilized to enable safe and high-speed grinding, and the grinder Since no overload occurs on the grinding wheel, the amount of wear of the grinding wheel relative to the amount of grinding of the burr is small, that is, the grinding ratio is high and the life of the grinding wheel is extended.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention; FIG. 1 is an overall configuration diagram, FIG. 2 is a configuration diagram mainly showing the moving mechanism, and FIG. 3 is a conventional configuration diagram. In the figure, 1 is an industrial robot, 1a is an arm, and 2
is a grinder, 3a is a burr, 5 is a current sensor, 7
is a microcomputer, 8 is a robot controller, 11 is a movement mechanism, 11a is a slide mechanism,
11c is a motor, and 11d is a limit switch.

Claims (1)

[Scope of utility model registration request] A robot that attaches a grinding tool to a hand portion at the tip of an industrial robot arm, connects the grinding tool to a drive power source, and controls the advancing speed of the arm in response to the drive current to the grinding tool based on the grinding load. In the device equipped with a controller, a moving mechanism for moving the grinding tool in the advancing direction of the arm and in the opposite direction is added to the hand section, and a circuit separate from the robot controller controls the moving mechanism in response to the drive current. A grinding overload prevention device comprising: a servo mechanism for moving the robot controller by motor drive; and means for detecting at least the end of the movement of the moving mechanism to control the robot controller.