JPS6244385A - Part holding and stationary method by robot - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for gripping and placing parts by a robot.

(Prior art) Conventionally, when a robot supplies or discharges flat parts (hereinafter referred to as workpieces), the method is to align or stack the workpieces in advance and grasp the workpieces in order to supply or discharge them. There is.

In that case, in order for the robot to grasp the workpiece, the number of sheets stacked on each workpiece must be grasped at the same point. The robot is taught to perform robot movements.

In addition, there are methods for gripping workpieces, such as gripping with a mechanical chuck, vacuum gripping, and electromagnet gripping, but in the case of a mechanical chuck, the configuration of the chuck is complicated when gripping workpieces stacked on a flat surface.

In addition, vacuum gripping has the problem of sucking in oil and chips, and furthermore, it cannot be used for workpieces with holes. In addition, in the case of an electromagnet, it is advantageous as a gripping method for thin steel plates and the like.

(Problem to be Solved by the Invention) However, in the case of the above method, when the electromagnet is used to grasp stacked workpieces or workpieces of various types, if the magnetic force is not properly adjusted, two or three workpieces may be grasped. There was a problem that they were attracted (grasped) at the same time, and that teaching (setting of height points depending on the work) had to be performed for each workpiece.

This invention is applicable to the above-described gripping of stacked workpieces and workpieces of various types using the electromagnet.
The problem is that if the magnetic force is not properly adjusted, two or three workpieces will be attracted (grasped) at the same time, and furthermore, teaching must be performed for each workpiece, which means that the origin has been removed. This provides a method for gripping and placing parts using a kit.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a method for gripping plate-like workpieces stacked on a plane and placing them in a predetermined place, in which a detection device provided in a gripping device is provided. The first sensor senses when the rod contacts the workpiece, temporarily halts the movement of the gripping device, and then drives the electromagnet adjacent to the workpiece by an adjacent distance appropriate for the workpiece recorded in the memory of the control device. grip the workpiece. When the workpiece is to be fixed, the workpiece is grounded, and when the detection rod detects the second sensor, the electromagnet is activated to separate the workpiece and set it in place. Furthermore, the detection rod is the first
．． If the third sensor is detected while the second sensor is not detected, an emergency stop command is issued.

(Function) In this way, when gripping, the sensor of cylinder 1 temporarily stops the robot operation, and then the gripping device adjoins the workpiece to the workpiece gripping position suitable for the workpiece according to the command of the program, and attracts the shake to the magnetic holder. This makes it possible to reliably pick up one sheet at a time. Also, in the case of stationary work, the second sensor determines the position from which the work is to be released, so that the work can be easily stationary. Therefore, the above-mentioned problem can be eliminated.

(Example) FIG. 1 is a perspective view showing an embodiment of the present invention.

In the figure, 1 is a robot arm, and 2 is a gripping device related to the present invention. °3 indicates stacked workpieces. 4 is a detection rod that detects the presence or absence of the workpiece 3; 51 is a detection rod that detects the presence or absence of the workpiece 3; A first sensor 52 is used to stop the operation of the workpiece, and a second sensor 53 is used to confirm that the workpiece 3 is grounded when it is fixed.
is the first. The second sensor 51 * 52 does not stop the operation and the third sensor 7 is a collision prevention device that detects the case where the detection rod 4 sinks further and is a magnetic holder that attracts and holds the workpiece 3 . 8 is a slide plate that can be replaced depending on the 50 types of workpieces, and includes the detection rod 4 and sensors 51p52t5.
3. The magnet holder 7 is fixed. 9 is an adapter for fixing this slide plate 8.

Next, the operation of gripping the workpiece 3 will be explained with reference to FIG. Incidentally, FIG. 3 is a flowchart diagram thereof. First, the workpiece 3 is gripped by the robot operation of processes (a) to (g) in the flowchart of FIG. 3 in accordance with the operation procedure shown below.

First, when the stacked workpieces 3 are to be gripped by suction to the top from above, the gripping device 2 attached to the tip of the robot arm 1 is approached from directly above the workpieces 3, and the detection rod 4 is brought into contact with the workpieces 3. When the first sensor 51 is detected, the robot operation is temporarily stopped.

Next, the gripping device 2 is moved adjacent to the workpiece gripping position suitable for the workpiece 3 according to the instructions of the program, and the magnetic holder 7
The workpiece 3 is sucked. This control block diagram is shown in the fourth
As shown in the figure. In the figure, reference numeral 11 denotes a servo control for controlling the rotational axis of the robot arm 1, and four servo controls are used for one rotation, one for the wrist, one for the elbow, and one for up and down. 12 is the sensor 51152
+53 (a photosensor is used in the example); an I10 processor that controls the input signal; 13 a memory that stores an adjacent distance suitable for the thickness of the workpiece 3; and a CPU 1
4, Operation B, OX I/F 15, External I/F 16,
It is composed of a subinterface 17, a calculation processor 18, and an interpolation calculation 19. Sir again? 111 in the control 11 is the counter, 112 is the D/A 111
3 is the servo amplifier A114 is the motor, 115 is the tacho generator, and 116 is A? shows a lus encoder. If, due to some accident, the first sensor 51 does not work, the gripping device 2 will still move straight down, and the detection rod 4 will detect the third sensor 53 for collision prevention and bring the robot to an emergency stop. Furthermore, if the third sensor 53 does not work, as an emergency measure for NC servo control in robot motion control, an emergency stop is performed if the deviation between the amount of feedback pulses and the amount of robot operation position command pulses exceeds a certain level. Using this method, we have taken safety measures in the program to stop the robot if a certain amount of force is applied.

Since double safety protection is provided in this way, it is possible to prevent the robot from running out of control. Next, detection rod 4
, the first sensor 51, and the magnetic holder 7 will be explained in more detail.

After the first sensor 51 is ONL and the robot stops operating, the magnet holder 7 moves to attract the work 3. It is necessary to change the adsorption force, and therefore the adsorption position must be set in advance.

When trying to grip various types of workpieces without limiting it to a specific workpiece, it is necessary to keep the gripping position (height) constant,
Either set the electromagnetic force (attractive force) of the magnetic holder 2 according to the characteristics of the workpiece 3, or keep the electromagnetic force (attractive force) of the magnetic holder 7 constant and change the gripping position (height) to attract it. There is a way to do it.

When changing the electromagnetic force of the magnet holder 7 to attract the workpiece 3, if the weight of the workpiece is large, the electromagnetic force must be made strong, but if it is too strong, the workpiece 3 will be excited and the workpiece 3 will be attracted as shown in Figure 5. A problem arises in that three sheets are suctioned at the same time.

The above disadvantages can be overcome by making it possible to change the height of the magnet holder 7 on the stand, and by making it possible to adjust or select a plurality of magnet holders 7 according to the characteristics (shape, weight, etc.) of the workpiece 3. It is removed. Magnetic holder 7 for gripping the tabshi work 3
The workpiece adsorption position is determined by the electromagnetic force of the magnet holder 7 (
If the adsorption force is constant, it must be adjusted up or down depending on the characteristics of the workpiece 3. The change (adjacent road (fund)
is taught in advance in the teaching program for robot operation. When the magnetic holder 7 is turned ONL and the workpiece 3 is attracted when the adjacent distance is reached, only one workpiece 3 is accurately grasped as shown in Fig. 6. can do.

Next, the case where the gripped workpiece is placed in place and released will be explained with reference to FIG.

First, Figure (a) shows the workpiece 3 being gripped (the first sensor 51 is ON) from directly above the place where the workpiece 3 is to be placed.
When the workpiece 3 touches the ground and the detection rod 4 sinks and the second sensor 52 detects it as shown in figure (b), the robot operation is stopped, the magnet holder 7 is turned off, and the workpiece 3 is lowered.
Release and let it rise as shown in (C). In the embodiment, the gripping portion is replaced by a slide plate 8 depending on the workpiece 3, and the magnet holder 7 is also movable as required.

(Effects of the Invention) As explained in detail above, according to the present invention, stacked plate-like workpieces can be grasped or placed one by one from above, so no Rlet is required to palletize (align) the workpieces. In addition, it is possible to grip and position the workpiece with a simple structure, and this makes it possible to teach the white-rotting operation, whereas in the past, teaching was done one workpiece at each gripping position and fixed position. Robot operation can be performed with only one point of instruction both during loading and unloading. Furthermore, it has a simple structure, is inexpensive, has a wide range of applications, and is extremely effective in handling robots.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the construction of an embodiment of the workpiece gripping and positioning method of the present invention, FIG. 2 is a schematic diagram of a workpiece gripping device, and FIG.
The figure is a flowchart showing the flow of workpiece gripping operation.
The figure is a control block diagram of the robot, Figure 5 is an explanatory diagram of a workpiece being gripped incorrectly, Figure 6 is an explanatory diagram showing a correct gripping state of a workpiece, and Figures 7 (,), (b), and (c) are an illustration of a workpiece being gripped incorrectly. FIG. l゛, 1... Robot arm section, 2... Gripping device,
3 monkey work, 4... detection rod, 51... first sensor,
52...Second sensor, 53...Third sensor, 7...
- Magnet holder, 8...Slide plate, 9...Adapter. Figure 2

Claims (1)

[Claims] (1) In a method of gripping plate-like workpieces stacked on a flat surface and placing them in a predetermined place, a first detection rod protrudes from the lower part of the gripping device and a detection rod that detects when the detection rod contacts the workpiece. A sensor, a second sensor that detects that the held workpiece has touched the ground at a fixed location, and a third sensor that detects when the detection rod sinks while the two sensors are not detecting this, When the detection rod of the gripping device contacts the workpiece, the first sensor detects the movement of the gripping device, and the electromagnet is moved adjacent to the workpiece by an adjacent distance suitable for the workpiece recorded in the memory of the control device. The workpiece is gripped by the drive, the workpiece is grounded, and when the detection rod detects the second sensor, the electromagnet is activated to release the workpiece and place it in place, and the detection rod also detects the first and second sensors. A method for grasping and fixing parts by a robot, characterized in that if a third sensor detects that the robot is in a state where the robot is in a state where the third sensor is in the same position, an emergency stop command is issued.