JPH07120184B2 - Teaching method for work positioning device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a teaching method for a work positioning device, for example, in a work positioning device for positioning and holding a plate-shaped work of an automobile body at a predetermined position, The locator which constitutes the work positioning device can hold the motor-operated work contact portion at the work positioning position with extremely high accuracy without damaging the teaching model.

(Prior Art) As a conventionally known locator which constitutes the work positioning device, there is, for example, one shown in FIG. 7 (Japanese Patent Laid-Open No. 59-12).
No. 0379).

In this locator, the rotary seat 2 is pivotally attached to the mounting bracket 1, and a plurality of, here, five gauge plates 3a, 3b, 3c, 3d, 3e are radially arranged on the outer peripheral surface of the rotary seat 2. Fixed at equal pitch, these gauge plates 3
Each of a, 3b, 3c, 3d, and 3e is indicated by 0 in the drawing, if necessary, by rotationally driving the rotary seat 2 by the switching actuator 4 provided on the mounting bracket 1 as well. It will be positioned and fixed in the working position.

Here, each gauge plate 3a, 3b, 3c, 3d, 3e
Includes a clamp mechanism 7 including a hinge lever type clamper 5 and an actuator 6 for opening and closing the clamper 5.

According to such a locator, one gauge plate having a gauge surface corresponding to the sectional shape of the work is selected,
Then, the selected gauge plate is positioned and fixed at the O position in the drawing by the rotation of the rotary seat 2 based on the operation of the switching actuator 4, so that the specific work is positioned and the clamp mechanism 7 acts. The work can be held.

By the way, such a locator uses the gauge plate when changing the shape of the work, changing the positioning position, etc.
Since it is necessary to move it to a predetermined position in the three-dimensional coordinate system, here, it is driven by a motor 9 in a direction orthogonal to the reciprocating direction on a jig base 8 that can reciprocate in one direction. It has a joint type manipulator 10
The respective joint motors 11, 1 provided on the manipulator 10 are
The gauge plate can be moved to a required position based on the operation of the motors 2, 13 and the motor 9 and the movement of the jig base 8.

In such a locator, the required gauge plate,
For example, as a teaching method for holding the gauge surface of the gauge plate 3a at a predetermined work positioning position, by operating the jig base 8 and the respective motors 9, 11, 12, 13 based on CAD data, The so-called CAD teach that brings the gauge surface of the gauge plate 3a to a predetermined three-dimensional coordinate position where the work should be positioned and supported, and, for example, the operation of the teaching pendant, the gauge plate 3a of the gauge plate 3a with respect to the reference surface A so-called model teach, in which the gauge surfaces are brought into close contact, is widely adopted.

(Problems to be solved by the invention) However, in such a conventional technique, when performing CAD teaching, the gauge surface of the gauge plate is changed in relation to the accuracy of CAD data, the installation accuracy of each locator, etc. There is a problem that it is not possible to hold at a predetermined work positioning position within a sufficiently satisfactory accuracy, for example, an error range of 0.1 to 0.3 mm, and when performing model teaching, the gauge surface of the gauge plate However, it is very difficult to determine whether or not the reference surface has come into contact with the specified force, and if the gauge surface is pressed too strongly against the reference display under the operation of each motor, the locator or model, master While there is a problem that the body etc. will be damaged, if there is a fear of such damage and the amount of proximity of the gauge surface to the reference surface is reduced, CAD As with the switch, there is a problem that it is impossible to improve the positioning accuracy of the gauge surface sufficiently.

The present invention has been made by paying attention to such problems of the prior art, and a so-called model teach is used as a locator,
A teaching method for a work positioning device, which can be performed with extremely high accuracy without fear of damaging a model or the like.

(Means for Solving Problems) A teaching method for a work positioning device according to the present invention is a work positioning device for positioning and supporting one work by a plurality of rotors. When contacting the work piece with the reference surface such as the model, master body, or the like without any gap, the work contacting portion is brought into contact with the reference surface, so that the drive torque of the motor exceeds the predetermined value. At the same time, the operation of the work contact portion is stopped and the work contact portion is held at the stop position.

(Operation) According to the teaching method of the work positioning device of the present invention, the work contact portion of the locator is brought into contact with the reference surface of the model, the master body or the like with a predetermined force without a gap based on the operation of the motor. This is detected when the driving torque of the motor exceeds a predetermined value, and the operation of the motor, and by extension, the work contact portion, is stopped,
By holding the work contact part at its stop position with a brake or the like built into the motor, the work contact part is completely removed from the risk of damage to the locator, model, master body, etc. It is possible to always and surely bring the work to a predetermined positioning position with the accuracy of.

(Example) Hereinafter, the present invention will be described based on illustrated examples.

FIG. 1 is a side view showing two types of locators that can be used for implementing the present invention, and FIG. 2 is a perspective view showing a positioning device to which those locators are applied.

Here, one locator L ₁ shown in FIG.
Manipulator that can be attached to and move in three dimensions
21 and a workpiece contact portion 24 attached to the tip of the workpiece 21 via a bracket 22 and swingable around a fulcrum 23, and pivotally supported by the bracket 22 to cause the workpiece contact portion 24 to swing. A motor 25, a screw means 26 driven by the motor 25, a clamper 27 pivotally supported on the work contact portion 24,
This is also equipped with a cylinder 28 that is attached to the work contact portion 24 and that causes the swing movement of the clamper 27 relative to it.
Further, the other locator L ₂ is a manipulator 29 similar to that described above, and a work contact portion 30 that is attached to the tip of this manipulator 29 and is slidable in the vertical direction in the figure along the tip surface thereof. , A motor 31 that controls the reciprocating motion of the work contact portion 30 and screw means (not shown), and a manipulator.
A work contact portion 33 pivotally supported at the tip of 29 via a bracket 32 and capable of swinging in a vertical plane, and a motor attached to the bracket 32 for causing the swing movement of the work contact portion 33.
34 and screw means 35.

Here, in each of the manipulators 21 and 29, as shown in the enlarged perspective view of FIG. 3, the first movable plate 39 is moved by the first drive mechanism 38 including the first motor 37 provided in the plate 36. In addition to being able to drive the fixed plate 36 in the X-axis direction of the illustrated rectangular coordinate system, a second drive mechanism 41 including a second motor 40 provided on the first movable plate 39 thereof, A second located on the first movable plate
The movable plate 42 of each of the plates 36, 39, 42 can be driven in the Y-axis direction shown in the drawing.
The columnar member 43 penetrating to the second side is directly connected to the second drive mechanism by the third drive mechanism including the third motor 44 attached to the lower end thereof.
The movable plate 42 can be driven together with its motor 44 in the Z-axis direction in the figure.

Therefore, according to the locators L ₁ and L ₂ , the manipulator 2
By the action of 1,29, the respective work contact portions 24, 30, 33 attached to their tips can be accurately moved to a predetermined three-dimensional position, and in addition, the respective work contact portions 24 , 30, 33 can also perform a swinging motion or a vertical motion in a vertical plane based on the operation of the respective motors 25, 31, 34.

In each of such locators, for example, the respective work contact portions are brought into contact with the outer surface of the master body M positioned and arranged on the temporary fixing welding stage S as shown in FIG. in order to, in the place indicated by the side view each locator in FIG. 1, a manipulator 21, 29 of the locator L _1, L _2, based on the CAD data, or based on the operation of the teaching pendant,
By the operation of the first to third motors 37, 40, 44, the work contact portions 24, 30, 33 are operated to a general position approaching the reference surface B, and the manipulators 21, 29 are positioned and fixed. After that, the oscillating motion of the work contact part 24 by the operation of the motor 25, the descending motion of the work contact part 30 by the operation of the motor 31, and the oscillating motion of the work contact part 33 by the operation of the motor 34 are performed. , The respective work contact portions 24, 30, 34 are brought into contact with the reference surface B without a gap with a predetermined pressing force, and held there.

Here, each of the work contact portions 24, 30, 34 is held at a predetermined positioning position by holding the respective motors 25, 3 when contacting the reference surface B with a predetermined pressing force.
Since the load of 1,34 increases sharply and the current value there also increases sharply, in such a case, the operation of the motors 25,31,34 is stopped and the built-in motors 25,31,34 The work contact parts 24, 30, 34
Is held in that position.

In addition, here, the first to third of each manipulator 21, 29
When the motors 37, 40, 44 of No. 1 are operated simultaneously with the motors 25, 31, 34, the first to third motors 37, 40, 44 are also
The motors 25, 31, and 34 can be made to function similarly.

FIG. 4 is a block diagram exemplifying the operation control circuit of the locator. Here, a manual operation command is issued from the teaching pendant 51 via the interface 52.
On the other hand, while inputting to the CPU 53, the CPU 53 outputs a command such as a current limit value and an operating position to the servo controller 55 based on a signal from the memory 54 that stores a processing program, data, etc. for each motor, and the servo Controller 55 causes actuation of a locator, eg, locator L ₁ , via amplifier 56, based on the command entered therein.

Here, the current value of the motor of the locator L ₁ , for example, the motor 25 and the coordinate position of the workpiece contact portion 24 are field-backed from the motor to the servo controller 55.

With the control circuit as described above, the work contact portion 24 of the locator L ₁ is moved to the reference surface B, especially the side roof rail thereof.
A case where B _{1 is} brought into contact with a desired pressing force without a gap will be described below with reference to the flowchart shown in FIG.

Here, first, the work contact portion 24 is connected to the manipulator.
21 or by the operation of it and the motor 25 brings it to a position near the side roof rail B ₁ and then selects the mode of the teaching pendant 51 to the model teach for the motor 25, which results in a memory 54
From CPU to CPU53, read the relationship between the drive torque and the current value in the state where the axial torque control parameter of the motor 25, in other words, the weight of each movable part including the work contact portion 24 and the like are taken into consideration. From servo controller 5
To 5 is input a limit value command of the current that increases due to the drive torque of the motor 25 exceeding a predetermined value. And then, based on the operation of the subsequent teach pendant 51, a servo controller 55, through the amplifier 56 actuates the locator L _1, the workpiece contact portions 24 that locator L ₁
However, when the drive torque of the motor 25 exceeds a predetermined value by contacting the master body M, and by extension, the side roof rail B ₁ with a predetermined force, in other words, when the motor current exceeds the limit value, Servo controller 55
To stop the movement of the workpiece contact portion 24 by stopping the motor operation command from the amplifier 56 to the amplifier 56, and hold the workpiece contact portion 24 due to the movement stop.

After the model teach for one work contact portion 24 is completed in this way, the same model teach is sequentially repeated for the other work contact portions.

Note that here, the relationship between the drive torque of the motor, in other words, the motor current and the stop of the work contact portion is, for example, the sixth
It can be expressed as shown in the figure, and the current limit value input from the CPU 53 to the servo controller 55 is a level that is considerably higher than the increase in the current value due to uneven operation of the workpiece contact part, dust, etc. The motor is stopped immediately only when a current exceeding the current limit value is generated, and the workpiece contact part is reliably prevented from moving excessively, and the desired positioning position is achieved. To
It can be positioned and held with high accuracy.

Thus, after completing the model teach for all the locators, the workpiece positioning position of each workpiece contact portion is stored in the memory 54 via the servo controller, and the workpiece contact portion is moved backward to remove the master body. In the actual tack welding work, the work abutting portions are re-advanced to the work positioning positions stored in advance and the tack welding of the vehicle body is performed, so that the vehicle body can be assembled with extremely high accuracy. .

(Effect of the Invention) Therefore, according to the teaching method of the present invention, in particular, the work contact portion is directly or indirectly contacted with the reference surface such as the model, the master body, or the like. When the drive torque of the motor that operates in the above condition exceeds a predetermined value, the work contact part is stopped from operating and the work contact part is held at its stop position, which completely damages the model, master body, etc. Without doing so, the workpiece contact portion can be brought into close contact with the reference surface with a required force, and the workpiece contact portion can be positioned extremely accurately at the workpiece positioning position.

[Brief description of drawings]

1 is a side view showing a locator used for implementing the present invention, FIG. 2 is a perspective view showing a positioning position to which the locator shown in FIG. 1 is applied, FIG. 3 is an enlarged perspective view of a manipulator, and FIG. FIG. 5 is a block diagram showing the operation control circuit of the locator, FIG. 5 is a flowchart showing the teaching procedure, FIG. 6 is a graph showing the relationship between the motor current and the work movement amount, and FIG. 7 is a diagram showing the conventional locator. is there. 21,29 …… Manipulator, 22,32 …… Bracket 24,30,33 …… Workpiece contact part 25,31,34 …… Motor, 26,35 …… Screw means 27 …… Clamper, 28 …… Cylinder 36 ...... Fixing plate, 37,40,44 ...... Motor 38,41 ...... Drive mechanism, L ₁ , L ₂ ...... Locator

Claims (1)

[Claims] 1. In a work positioning device for positioning and supporting one work by a plurality of locators, a work contact portion of each locator for operating a motor is brought into contact with a reference surface without a gap to specify a work positioning position. When the driving torque of the motor exceeds a predetermined value due to the contact of the work contact part with the reference surface, the operation of the work contact part is stopped and the work contact part is stopped. A teaching method for a work positioning device, characterized by holding at a position.