JPH0222712A - Teaching method for work positioning device - Google Patents

Abstract

PURPOSE:To accurately position a work by stopping the operation of a work contact part driven with a motor to hold it in the stop position at the time when the driving torque of the motor exceeds a prescribed value by contacting of said work contact part at the time of bringing the work contact part into contact with a reference surface without a gap between them to specify the position. CONSTITUTION:Manipulators 21 and 29 constituting locators L1 and L2 are operated to accurately move work contact parts 24, 30, and 33 provided in their front ends to prescribed three-dimensional positions. Thereafter, these contact parts 24, 30, and 33 are shaked or vertically moved in a vertical plane by motors 25, 31, and 34 and are surely brought into contact with the reference surface. Since loads of motors 25, 31 and 34 are quickly increased and motor current values are quickly increased consequently when they are brought into contact with the reference surface, these current values are used for positioning to stop motors and incorporated brakes are used to hold contact parts 24, 30, and 34 in these stop positions.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a teaching method for a workpiece positioning device. The motor-operated workpiece abutting portion of each locator constituting the workpiece positioning device can be held at the position of the workpiece with extremely high precision without damaging the teaching model.

(Prior Art) As a conventionally known locator constituting a workpiece positioning device, there is, for example, the one shown in FIG.
No. 120379).

In this locator, a rotating seat 2 is pivotally attached to a mounting bracket 1, and a plurality of gauge plates 3a, five in this case, are mounted on the outer peripheral surface of the rotating seat 2.

3b, 3c, 3d, and 3e are fixed radially at equal pitches, and these gauge plates 3a, 3b,
3c, 3d+3e, each of which also rotates the rotary seat 2 by the switching actuator 4 provided on the mounting bracket 1, so that the rotary seat 2 can be rotated as required.
In the figure, it is positioned and fixed at the working position indicated by 0.

Here, each gauge plate 3a, 3b.

3c, 3d, and 3e are the clampers 5 on the second hinge lever.
and an actuator 6 that opens and closes this clamper 5.
A clamp mechanism 7 is provided.

According to such a locator, a single gauge plate with a gauge surface corresponding to the cross-sectional shape of the workpiece is selected, and
Then, by positioning and fixing the selected gauge plate at the 0 position in the figure by rotating the rotary seat 2 based on the operation of the switching actuator 4, in addition to positioning the specific workpiece, the operation of the clamp mechanism 7 The work can be held.

By the way, such a locator uses the gauge plate when changing the shape of the workpiece or changing the positioning position.
Since it is necessary to move the jig to a predetermined position in the three-dimensional coordinate system, a jig base 8 that can reciprocate in one direction is mounted on the jig base 8 and is driven by a motor 9 in a direction perpendicular to the reciprocating direction. Based on the operation of the respective joint motors 11, 12, 13 and motor 9 provided on this eyebrow break 10, and the movement of one stroke 8 to the jig, the gauge plate is moved to the desired position. This makes it possible to move to.

In such a locator, the required gauge plate,
For example, a teaching method for holding the gauge surface of the gauge plate 3a at a predetermined workpiece positioning position includes operating the jig base 8 and the respective motors 9, 11, 12, and 13 based on CAD data. Gauge play) Gauge plate 3a is moved relative to a reference surface of a model, master body, etc. by so-called CAD teaching, which brings the gauge surface of 3a to a predetermined three-dimensional coordinate position where the workpiece is to be positioned and supported, and by, for example, operating a teaching pendant. The so-called model teach method, in which the gauge surface of the gauge is brought into close contact with the gauge surface, is widely used.

(Problems to be Solved by the Invention) However, in such conventional technology, when performing CAD teaching, the gauge surface of the gauge plate is Satisfactory accuracy, e.g. 0.1 to 0.3 mm
There is a problem in that it is not possible to hold the workpiece in a predetermined position within a certain error range, and when performing model teaching, the gauge surface of the gauge plate is in contact with the reference surface with a predetermined force. It is extremely difficult to determine whether or not the locator, model, master body, etc. will be damaged if the gauge surface is pressed too strongly against the reference surface while each motor is operating. On the other hand, if the amount of approach of the gauge surface to the reference surface is reduced due to fear of such damage, CA
As in the case of D-Tee 1,000, there was a problem in that the positioning accuracy of the gauge surface could not be sufficiently improved.

This invention was made by focusing on the problems of the prior art, and it is possible to perform so-called model teaching by using a locator,
The present invention provides a teaching method for a workpiece positioning device that can be performed with extremely high accuracy without fear of damaging a model or the like.

(Means for Solving the Problems) A teaching method for a workpiece positioning device according to the present invention is a workpiece positioning device in which one workpiece is positioned and supported by a plurality of rotors. When specifying the positioning position of the workpiece by contacting the part without any gaps with the model, master body, or other reference surface, the drive torque of the motor exceeds a predetermined value by bringing the workpiece contact part into contact with the reference surface. When the workpiece contact part stops operating,
It is characterized by holding the workpiece contact portion at its stop position.

(Function) According to the teaching method of the workpiece positioning device of the present invention, the workpiece contact portion of the locator is brought into contact with the model, master body, or other reference surface with a predetermined force without any gaps based on the operation of the motor. This is detected when the drive torque of the motor exceeds a predetermined value, and the motor and, by extension, the workpiece contacting section are stopped from operating, and the workpiece contacting section is moved to the stop position using a built-in motor. By holding the workpiece with a brake or other means, the workpiece contact part can be constantly and accurately positioned at the desired position on the workpiece, completely eliminating the risk of damage to the locator, model, master body, etc. can be delivered with certainty.

(Example) The present invention will be explained below based on illustrated examples.

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

Here, one of the locators L shown in FIG. Possible workpiece contact part 24
, a motor 25 that is pivotally supported by the bracket 22 and causes a rocking motion of the workpiece contact portion 24;
A clamper 27 is pivotally supported on the workpiece abutting part 24, and a cylinder 28 is also attached to the workpiece abutting part 24 and provides a swinging movement of the clamper 27 relative to the workpiece abutting part 24. , and the other locator L
2 includes a manipulator 29 similar to the one described above, a workpiece abutting part 30 that is attached to the tip of the manipulator 29 and can slide vertically in the figure along its tip surface, and this workpiece abutting part. 30, a screw means (not shown), a workpiece contact part 33 which is pivotally supported at the tip of the manipulator 29 via a bracket 32 and can swing in a vertical plane, and is attached to the bracket 32. A motor 3 that causes a swinging movement of the workpiece contact portion 33
4 and screw means 35.

Here, in each manipulator 21.29, the third
As shown in the enlarged perspective view in the figure, a first movable plate 39 is moved relative to the fixed plate 36 by a first drive mechanism 38 including a first motor 37 provided on the plate 36.
In addition to being able to drive in the X-axis direction of the illustrated orthogonal coordinate system, the second motor 4 provided on the first movable plate 39
A second movable plate 42 located on the first movable plate can be driven relative to it in the Y-axis direction in the figure by a second drive mechanism 41 including the respective plate 1. - A columnar member 43 penetrating through 36, 39, 42 is directly connected to the second movable plate 42 by a third drive mechanism including a third motor 44 attached to its lower end, along the X axis in the figure. direction, together with its motor 44.

Therefore, according to this locator LI+ Lz, each of the workpiece contact parts 24, 30, 33 attached to their tips can be accurately moved to a predetermined three-dimensional position by the action of the manipulator 21, 29, In addition, each of these workpiece abutments 24.30.33 can also perform an oscillating movement or an up-and-down movement in the vertical plane due to the activation of the respective motor 25.31.34.

In each of these locators, for example, each workpiece contact portion is brought into close contact with the outer surface of the master body M positioned and arranged on the temporary welding stage S as shown in FIG. In doing so, the manipulators 21, 29 of each locator, locators L, L2, shown in side view in FIG.
By operating the first to third motors 37.40.44 based on the data or based on the operation of the teaching pendant, the workpiece contact portion 24.30.33 is operated to an approximate position approaching the reference surface width. After positioning and fixing each of the manipulators 21 and 29, the motor 2
The rocking motion of the workpiece contact portion 24 due to the operation of 5, and
The operation of the motor 31 causes a downward movement of the workpiece contacting part 30 and the operation of the motor 34 causes a swinging movement of the workpiece contacting part 33, so that the respective workpiece contacting parts 24
．． 30.34 is brought into contact with the reference surface B with a predetermined pressing force without a gap, and held there.

Here, each of these workpiece contact parts 24, 30, 34,
Holding at a predetermined positioning position is such that when they come into contact with the reference surface B with a predetermined pressing force, the load on each motor 25, 31, 34 increases rapidly, and the current value there also increases rapidly. In such a case, the operation of the motors 25, 31, and 34 is stopped, and the work contact portions 24, 30, and 34 are held in their respective positions by the brakes built into each motor 25, 3L, and so on. It is done by doing.

Note that here, the first to
3rd motor 37.40.44, each motor 25.3L
34, the first to third motors 37.40.44 can also function in the same way as the motors 25.31.34.

FIG. 4 is a block diagram illustrating the operation control circuit of the locator. Here, a manual operation command is input from the teaching pendant 51 to the CPU 53 via the interface 52, while the CPU 53
Based on signals from the memory 54 that stores processing programs, data, etc. for each motor, commands such as current limit values and operating positions are output to the servo controller 55;
The servo controller 55 causes actuation of a locator, for example locator L1, via an amplifier 56 based on commands input thereto.

Here, the current value of the motor of the locator L1, for example, the motor 25, and the coordinate position of the workpiece contact portion 24 are fed back from the motor to the servo controller 55.

In the case where the workpiece contacting portion 24 of the locator L is brought into contact with the reference surface B, particularly the side roof rail B1, with the desired pressing force without any gap and with the desired pressing force, the control circuit as described above is shown in FIG. This will be explained below based on the flowchart shown in FIG.

Here, first, the workpiece contact part 24 is operated by the manipulator 21 or by the operation of the manipulator 21 and the motor 25.
The mode of the teaching pendant 51 is set by the motor 25.
As a result, the shaft torque control parameters of the motor 25, in other words, the shaft torque control parameters of the workpiece contact portion 24 are transferred from the memory 54 to the CPIJ 53.
Read the relationship between drive torque and current value, taking into consideration the weight of each moving part including
A limit value command for the current that increases due to the drive torque of the motor 25 exceeding a predetermined value is inputted from the U53 to the servo controller 55. Thereafter, based on the subsequent operation of the teach pendant 51, the servo controller 55 operates the locator L via the amplifier 56, and the workpiece contact portion 24 of the locator L1 is connected to the master body M1 and the side roof rail B1.
By contacting with a predetermined force, when the drive torque of the motor 25 exceeds a predetermined value, in other words, when the motor current exceeds a limit value, a motor operation command is sent from the servo controller 55 to the amplifier 56. As a result, the movement of the work contacting portion 24 is stopped, and the work contacting portion 24 is held due to the stoppage of movement.

After completing the model teaching for one workpiece contacting portion 24 in this manner, the same model teaching is sequentially repeated for the other workpiece contacting portions.

Here, the relationship between the drive torque of the motor, in other words, the motor current, and the stoppage of the workpiece contact section is, for example, the sixth
The current limit value input from the CPU 53 to the servo controller 55 can be expressed as shown in the figure, and the current limit value input from the CPU 53 to the servo controller 55 can be set to a level considerably higher than the increase in current value caused by uneven operation of the workpiece contact part, dust, and other influences. By setting the motor to a current limit value and immediately stopping the motor only when a current exceeding the current limit value occurs, the workpiece contact part is reliably prevented from moving excessively and positioned at the desired position. It can be positioned and held with high precision.

In this way, after completing model teaching for all locators, the workpiece positioning position of each workpiece contact part is stored in the memory 54 via the servo controller, and the workpiece contact part is moved backward to remove the master body. Then, during the actual tack welding work, each workpiece contact part is re-advanced to the previously memorized workpiece positioning position and tack welding is performed on the car body, making it possible to assemble the car body with extremely high precision. .

(Effect of the invention) Therefore, according to the teaching method of the present invention, in particular, by bringing the workpiece contacting portion into contact with a model, master body, or other reference surface, the workpiece contacting portion can be directly or indirectly brought into contact with the workpiece contacting portion. When the drive torque of the motor that operates exceeds a predetermined value, the operation of the workpiece contact part is stopped and the workpiece contact part is held at the stopped position, thereby preventing any damage to the model, master body, etc. It is possible to bring the work contact portion into sufficient contact with the reference surface with a required force without having to do so, and to position the work contact portion extremely accurately at the position of the workpiece.

[Brief explanation of the drawing]

Fig. 1 is a side view showing a locator used in carrying out the present invention, Fig. 2 is a perspective view showing a positioning device to which the locator shown in Fig. 1 is applied, Fig. 3 is an enlarged perspective view of the manipulator, and Fig. 4 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 motor current and workpiece movement amount, and Fig. 1 shows a conventional mouth/cutter. It is a diagram. 21, 29... Manipulator 22.32... Bracket 24, 30.33... Work contact portion 25, 31.34... Motor 26.35... Screw means 27... Clamper 28. ...Cylinder 36...Fixing plate 37.40.44...
・Motor 38, 41... Drive mechanism L, L2
...Locator patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] 1. In a workpiece positioning device that positions and supports a workpiece using a plurality of locators, the motor-operated workpiece contacting portion of each locator is brought into contact with a reference surface without any gaps, and the workpiece is positioned and supported by a plurality of locators. When specifying the positioning position, when the drive torque of the motor exceeds a predetermined value due to the contact of the workpiece contacting part with the reference surface, the operation of the workpiece contacting part is stopped, and the workpiece contacting part is stopped. A teaching method for a workpiece positioning device characterized by holding a part at a stop position.