JP2007130720A - Work positioning method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To position a work held by a gripper in a predetermined position. <P>SOLUTION: The gripper 10 includes a fixed pawl 22 and a movable pawl 26, wherein the pawls 22, 26 are respectively provided with a gripping pad 28. The gripping pad 28 where an elastic body 36 and a spherical body 38 are accommodated in the interior is deformed to a shape corresponding to the shape of a door mirror 14 when the door mirror 14 (a work) is gripped. The gas is discharged from the interior of the gripping pad 28 to thereby position and fix the spherical body 38. When a screw part 18 of the door mirror 14 is inserted in a pilot hole 52, the degree of decompressing a predetermined gripping pad 28 is lowered, whereby the gripping pad 28 is restored to the initial state. According to this restoration, the door mirror 14 is pressed and the door mirror 14 is positioned in a predetermined position. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a workpiece positioning method and apparatus for positioning a workpiece at a predetermined position.

  In a gripping device that grips a workpiece so as to sandwich the workpiece from both sides, a pad that can be deformed into a shape corresponding to the shape of the workpiece may be provided at a portion where the workpiece abuts. For example, Patent Document 1 proposes gripping a workpiece with a chuck provided with a so-called air bag capable of supplying and exhausting air.

  In this case, a large number of balls are enclosed inside the airbag. When the chuck is closed and the airbag contacts the outer surface of the workpiece, the gas inside the airbag is exhausted. According to Patent Document 1, when the inside of the airbag is evacuated with exhaust, each ball is in a fixed state. As a result, the airbag is fixed to a shape corresponding to the shape of the outer surface of the workpiece. It is supposed that the airbag comes into contact with the outer side surface with substantially equal pressure, and the clamping state is good.

JP-A-6-206622

  By the way, the gripped work may be attached to some other part. For example, there is a case where a thread portion exists in the work and the thread portion is inserted into a screw hole of another component.

  In this case, even if the screw part is inserted into the screw hole, if the screw part is inclined with respect to the screw hole, it is difficult to tighten the nut against the screw part. Need to do. However, in this case, it is necessary to inspect whether or not the screw portion is inclined, which is complicated. Therefore, in such a case, it is desired to insert the screw portion into the screw hole with high accuracy.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a workpiece positioning method and apparatus capable of accurately positioning a workpiece at a predetermined position.

To achieve the above object, the present invention provides a workpiece positioning method for positioning a workpiece,
A step of gripping the workpiece with a gripping device provided with a gripping pad at a portion where the workpiece abuts;
Discharging gas from the inside of the gripping pad deformed into a shape corresponding to the shape of the workpiece;
Transporting the workpiece to a predetermined position with the gripping device;
Reducing the degree of decompression of the gripping pad to restore the gripping pad to its original shape, and pressing and displacing the workpiece;
It is characterized by having.

  In the present invention, when the workpiece is gripped, the gas inside the gripping pad is discharged, while when the workpiece is positioned, the discharge of the gas is stopped. With this stop, the degree of decompression inside the gripping pad decreases, so that the gripping pad attempts to restore its original shape. Following this, the workpiece is pressed, and as a result, the workpiece is positioned at the normal position.

  That is, according to the present invention, the discharge of the gas from the gripping pad is stopped, and the gripping pad is restored thereby, so that the workpiece can be positioned at a predetermined position easily and with high accuracy.

Further, the present invention is a workpiece positioning device for positioning a workpiece,
A gripping device provided with a gripping pad at a site where the workpiece contacts,
Gas discharging means for discharging gas from the inside of the gripping pad;
Control means capable of controlling the amount of gas discharged from the gripping pad to control the degree of decompression of the gripping pad;
It is characterized by having.

  By adopting such a configuration, the degree of restoration of the gripping pad can be adjusted, and eventually the amount of workpiece displacement can be determined.

  According to the present invention, the gas inside the gripping pad is exhausted to maintain the deformed state, while the degree of decompression is reduced to restore the gripping pad. By performing a simple operation of pressing the workpiece in accordance with the reduction in the degree of decompression, an effect is obtained that the workpiece can be easily and accurately positioned at a predetermined position.

  Hereinafter, preferred embodiments of the workpiece positioning method according to the present invention in relation to an apparatus for carrying out the workpiece positioning method will be described and described in detail with reference to the accompanying drawings.

  First, a schematic overall perspective view of a gripping device for carrying out the workpiece positioning method is shown in FIG. 1, and a schematic plan view thereof is shown in FIG. This gripping device 10 is incorporated at the tip of an arm unit 12 in a 6-axis robot (not shown), and grips an automobile door mirror 14 as a workpiece. In addition, three screw portions 18 are fixed to the bottom surface of the neck portion 16 of the door mirror 14 so as to protrude.

  The gripping device 10 includes a cylinder 20, a fixed claw 22 connected and fixed to the rear end portion of the cylinder 20, and a movable claw 26 connected to the tip of a rod 24 that constitutes the cylinder 20. Of course, the fixed claw 22 and the movable claw 26 are attached to the cylinder 20 so as to face each other. Reference numerals 27a and 27b in FIGS. 1 and 2 denote guide rods.

  In this case, the fixed claw 22 is provided with six grip pads 28 on the end face facing the movable claw 26 and one on each side face. The grip pad 28 has a plate-like support member 30 continuous from the end face or side surface of the fixed claw 22, and a rubber cover 32 protruding from the support member 30, and as shown in FIG. An elastic body 36 having a through hole 34 and a large number of spheres 38 are accommodated.

  The elastic body 36 may be made of any material that exhibits flexibility when a force is applied from the outside and returns to its original shape when the force is removed. For example, rubber or sponge is selected. Is done.

  On the other hand, as the sphere 38, for example, a glass bead having a diameter of 0.75 mm can be selected.

  A discharge passage (not shown) is provided on the end face and the side surface of the fixed claw 22, and this discharge passage continues to the support member 30. An exhaust tube 44 is connected to the discharge passage via a pipe joint 40 and an ejector 42. That is, the gas inside the grip pad 28 can be exhausted under the action of the ejector 42. An automatic opening / closing valve (not shown) is interposed downstream of the exhaust tube 44.

  The grip pad 28 provided on the end face of the movable claw 26 facing the fixed claw 22 is also configured in the same manner as described above. Therefore, the same components are denoted by the same reference numerals and detailed description thereof is omitted. To do.

  Here, the movable claw 26 is provided with a touch sensor 46. The touch sensor 46 has a flexible touch bar 48, and the touch bar 48 is displaced upward in FIG. 2 when the end surface of the door mirror 14 comes into contact therewith.

  The workpiece positioning method according to the present embodiment is performed as follows using the above-described gripping device 10.

  First, the door mirror 14 which is a workpiece is waiting at a predetermined position of a transfer system (not shown). The six-axis robot operates appropriately to hold the door mirror 14 and moves the arm unit 12 to a predetermined position.

  Next, the cylinder 20 is energized, whereby the rod 24 is lowered from the position of the two-dot chain line in FIG. 2 to the position of the solid line. As a result, the door mirror 14 is sandwiched between the fixed claw 22 and the movable claw 26.

  When the door mirror 14 is clamped, the touch bar 48 constituting the touch sensor 46 abuts on the door mirror 14 and is displaced upward (see FIG. 2), thereby a control unit (not shown) that controls the operation of the 6-axis robot. ), It is recognized that the gripping device 10 has pinched the door mirror 14.

  At this time, a predetermined portion of the door mirror 14 presses the grip pad 28. For this reason, the rubber cover 32 of the grip pad 28 is slightly crushed as shown in FIG. At the same time, the sphere 38 inside the grip pad 28 flows, and the elastic body 36 is slightly crushed and swells in the lateral direction in FIG. Eventually, the grip pad 28 is deformed into a shape corresponding to the shape of the door mirror 14.

  In this state, the automatic opening / closing valve is opened under the control action of the control unit, and the gas in the gripping pad 28 is exhausted. That is, the inside of the gripping pad 28 is in a reduced pressure state, whereby the sphere 38 is positioned and fixed.

  While such exhaust is continued, the 6-axis robot operates appropriately to move the arm portion 12 to a predetermined position, and the door mirror 14 is inserted into the screw hole 52 of the automobile door 50 as shown in FIG. The screw part 18 is passed. At this time, the screw portion 18 may be inserted so as to be inclined with respect to the screw hole 52.

  In such a case, in the present embodiment, the degree of decompression in the grip pad 28 is adjusted. That is, the control unit (not shown) closes the automatic opening / closing valve so as to have a predetermined opening, and reduces the exhaust amount exhausted under the action of the ejector 42. Of course, the automatic open / close valve may be fully closed to reduce the exhaust amount to zero. That is, the restoration of the gripping pad 28 may be performed by returning the inside of the gripping pad 28 to the atmospheric pressure, or may be performed by setting the pressure lower than the atmospheric pressure.

  In this manner, in the gripping pad 28 with the degree of decompression reduced, the degree of positioning and fixing of the sphere 38 decreases following this reduction, and the elastic body 36 tries to return to the original shape based on elastic restoration. The grip pad 28 (rubber cover 32) attempts to return to its original shape, and eventually the door mirror 14 is pressed by the grip pad 28 to be restored.

  When the shape of the grip pad 28 is restored to the original state or halfway, the door mirror 14 is pressed by the grip pad 28. As a result, as shown in FIG. 6, one end of the door mirror 14 is pressed, whereby the threaded portion 18 that is inclined with respect to the threaded hole 52 is positioned at the normal position.

  As described above, in the present embodiment, the degree of pressure reduction of the grip pad 28 at the position corresponding to the position where the door mirror 14 is displaced is reduced, and at this time, the door mirror is restored by the elastic restoring force of the elastic body 36 inside the grip pad 28. 14 is displaced. Thereby, the door mirror 14 can be easily and accurately arranged at the regular position. Therefore, as before, it is not necessary to check whether or not the screw portion 18 is arranged at the normal position, and when it is not the normal position, it is not necessary to correct the normal position.

  That is, according to the present embodiment, it is possible to accurately position the door mirror 14 at the normal position without performing complicated work.

  Thereafter, the nut is screwed into the screw portion 18 positioned at the regular position, and the door mirror 14 is positioned and fixed to the automobile door 50.

  When the grip pad 28 is completely separated from the positioned and fixed door mirror 14, the grip pad 28 (rubber cover 32) returns to its original shape based on the elastic restoring force of the elastic body 36. For this reason, the gripping device 10 can easily grip a door mirror having a different shape from the door mirror 14.

  As shown in FIG. 7, a planar rectangular frame 54 made of an elastic member is installed on the support member 30, and the upper part of the through hole 56 of the frame 54 is closed with a rubber cover 58. A gripping pad 60 may be employed. In this case, as shown in FIG. 8, when the door mirror 14 is clamped, the frame body 54 is deformed into a shape corresponding to the shape, and the gas inside the gripping pad 60 is discharged in this state. Instead of the rectangular frame 54, an annular frame may be adopted.

  In either case, a vacuum pump may be used instead of the ejector 42 as the gas discharge mechanism. Of course, other intake means may be used.

  Needless to say, a workpiece other than the door mirror 14 may be positioned.

  Furthermore, instead of the sphere 38 accommodated in the grip pads 28 and 60, for example, a solid in a columnar shape or a cylindrical shape may be accommodated in a flowable manner. Alternatively, the sphere 38 and the substitute object may not be accommodated in the grip pads 28 and 60.

It is a general | schematic whole perspective view of the holding | gripping apparatus for enforcing the workpiece | work positioning method which concerns on this Embodiment. It is a schematic plan view of the holding | gripping apparatus of FIG. It is a general | schematic whole longitudinal cross-sectional view of the holding | grip pad which comprises the holding | grip apparatus of FIG. It is a schematic whole longitudinal cross-sectional view which shows the state by which the holding pad of FIG. 3 was pressed by the door mirror. It is principal part sectional explanatory drawing which shows the state by which the thread part of the door mirror was passed through the screw hole of the door for motor vehicles. It is principal part cross-sectional explanatory drawing which shows the state in which the screw part inclined with respect to the screw hole was positioned in the regular position. It is a general | schematic whole longitudinal cross-sectional view of the grip pad of another structure from the grip pad of FIG. It is a schematic whole longitudinal cross-sectional view which shows the state by which the grip pad of FIG. 7 was pressed by the door mirror.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Gripping device 14 ... Door mirror 18 ... Screw part 20 ... Cylinder 22 ... Fixed claw 24 ... Rod 26 ... Movable claw 28, 60 ... Grip pad 30 ... Support member 32, 58 ... Rubber cover 34, 56 ... Through-hole 36 ... Elastic body 38 ... Sphere 42 ... Ejector 44 ... Exhaust tube 46 ... Touch sensor 48 ... Touch bar 50 ... Automotive door 52 ... Screw hole 54 ... Frame (elastic body)

Claims (2)

A workpiece positioning method for positioning a workpiece,
A step of gripping the workpiece with a gripping device provided with a gripping pad at a portion where the workpiece abuts;
Discharging gas from the inside of the gripping pad deformed into a shape corresponding to the shape of the workpiece;
Transporting the workpiece to a predetermined position with the gripping device;
Reducing the degree of decompression of the gripping pad to restore the gripping pad to its original shape, and pressing and displacing the workpiece;
A workpiece positioning method characterized by comprising: A workpiece positioning device for positioning a workpiece,
A gripping device provided with a gripping pad at a site where the workpiece contacts,
Gas discharging means for discharging gas from the inside of the gripping pad;
Control means capable of controlling the amount of gas discharged from the gripping pad to control the degree of decompression of the gripping pad;
A workpiece positioning apparatus characterized by comprising:

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