JP3129693B2 - Work holding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of a workpiece gripping mechanism used for a robot hand which grips a workpiece and processes the workpiece by a processing machine, and more particularly, to a workpiece which is effective when various casting workpieces and the like are handled in a flow operation. It relates to a gripping device.

[0002]

2. Description of the Related Art For example, in a foundry with advanced automation,
The process includes a step of holding the cast work by a robot hand, pressing the work against a grinding machine, shaving off unnecessary parts such as burrs, and adjusting the shape of the casting. Conventionally, a robot hand used for such an application has a structure in which two opposing plate-shaped fingers are translated, opened and closed, and pressed and held in parallel by a fingertip. In the gripping finger having such a structure, when the workpiece to be pressed by the gripping finger has irregularities such as the skin of a cast metal as cast, the gripping finger and the workpiece come into contact at the top of the convex portion of the workpiece, In some cases, it was not possible to support the surface, and the gripping force was substantially reduced in some cases. In addition, since the contact point between the gripping finger and the work is not at a fixed position, the gripping posture is unstable.

In order to solve such inconveniences, there is a type in which a gripping claw, such as a triangular prism, is attached to a plate-like portion of a gripping finger, and the work is pressed by the gripping claw.
Accordingly, even if the surface of the workpiece to be gripped has irregularities, the workpiece can always be brought into contact with a fixed position, so that the stability of gripping can be ensured. However, when performing finishing work on various types of work using gripping claws with such a structure, prepare a variety of hands with claw intervals according to the size of the work, and change the hand according to each work In some cases, finishing work has to be interrupted due to hand replacement.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the problem that the work to be processed by the robot hand is not interrupted by hand exchange even if the work has various sizes and forms. It is an object of the present invention to provide a work holding device for a robot hand which can hold each work with a sufficient holding force and apply the work to a machine tool.

[0005]

In order to solve the above-mentioned problems, a work gripping device according to the present invention is characterized in that two parallel fingers having two gripping claws are translated and opened and closed in opposing directions. A four-point contact type parallel two-fingered hand for holding a workpiece with individual gripping claws, characterized in that it operates so as to adjust the distance between gripping claws attached to the fingers.

In the work gripping device of the present invention, the gripping claw spacing corresponding to the size and the shape of the work can be selected by making at least one gripping claw of each finger movable, so that the work can be gripped with a sufficient gripping force. You can grab it. Also, when switching between the long side and the short side of the work, the claw interval can be selected according to the length. Furthermore, even when the workpiece comes into contact with the surface of the work having irregularities, the workpiece is supported by the ridge line and does not become unstable.

Further, if all the gripping claws are movable, the two gripping claws provided on one finger can be made at the same distance from the center line of the finger, and when the work is fixed with the gripping claws. Since the force applied from the gripping claws is averaged, the workpiece can be gripped more reliably.

Further, by holding the gripping claw to the opening / closing hand via an elastic body such as a spring, the gripping surface 2 of the workpiece is fixed.
Even when the surfaces are not exactly parallel or when the work surface has burrs or unexpected irregularities, the gripping claws expand and contract according to the irregularities, so that the four gripping claws always contact and provide sufficient gripping force with four-point support Can support the work.

It is also conceivable that the shape of the work is determined by using a camera and an image processing device with respect to the work gripping device, and the spacing between the gripping claws is automatically determined and reflected. The shape of the target work is photographed by a camera, and the image is sent to an image processing device. The image processing apparatus confirms the shape of the work, determines the corresponding gripping claw spacing, and sends the result to the claw spacing varying mechanism. Also, here the image processing device measures not only the shape but also the irregularities existing on the target work and the shape and location of the burr, etc.
It is also possible to determine the gripping claw position corresponding to this.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A work gripping mechanism used in a robot hand according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a perspective view of one embodiment of a work holding mechanism according to the present invention. Referring to the figure, the robot hand 1 is provided with two fingers facing in parallel. First finger 2
The second finger 3 and the second finger 3 are each provided with a variable claw spacing mechanism 4 on the opposing surface side of the tip. The gripping claws 5 are attached to the surface on which all the gripping claws 5 exist so as to move perpendicularly to the moving direction of the finger, and have a sharp edge toward the inside from the nail spacing variable mechanism 4.

The robot hand 1 is used, for example, fixed to an arm of an articulated robot. The interval between the gripping claws 5 is changed according to the width of the work 10 by the variable jaw interval mechanism 4 according to the size of the work 10, and the two fingers 2,
When the translation 3 is performed while maintaining the posture, the four gripping claws 5 arranged on a substantially flat surface come into contact with both side surfaces of the work 10 so that the work 10 can be firmly gripped by the edge of the toe.

FIGS. 2 (a) and 2 (b) are views for explaining the operation of the workpiece gripping mechanism. FIG. 2 shows a state in which the workpiece gripping device shown in FIG. 3 shows a state in which the work 12 having a short work piece 12 is grasped from the work side.

As shown in FIG. 2 (a), when the robot hand 1 grips the workpiece 11 having a long gripping side length, the claw distance d is adjusted by the variable claw spacing mechanism 4 to match the length of the gripping side length. Spreading. Thereby, the gripping surface 2 of the work
The gripping claws can be located near each end of the surface, and the workpiece 10 can be gripped reliably. FIG. 2
As shown in (b), when the robot hand 1 grips the workpiece 12 having a short gripping side length, the nail interval d is narrowed by the nail interval variable mechanism 4 to maintain an appropriate nail interval for gripping the workpiece. be able to.

In this way, by generally changing the claw distance according to the gripping side length of the target work by the variable claw spacing mechanism 4, the gripping claws can be positioned near both ends of the gripping surface 2 of the target work. It is possible. As a result, works of various sizes can be reliably held.

FIG. 3 shows an example of the variable pawl spacing mechanism 4. Referring to the figure, the motor 8 is connected to rotate the feed screw 7 via the gear 9, and the gripping claw 5 is engaged with the threaded portion of the feed screw 7. When the motor 8 rotates and is appropriately decelerated by the gear 9, and the feed screw 7 rotates accordingly, the gripping claw 5 moves by the pitch cut by the feed screw 7. The direction of the feed screw 7 is changed at the position of the gear 9, and when the feed screw 7 rotates in one direction, both gripping claws 5 advance in opposite directions.

Therefore, depending on the number of rotations of the motor 8,
The position of the gripping claw 5 can be determined. In this way, the gripping claw distance d can be set to an arbitrary size, so that an appropriate gripping claw distance d corresponding to various target workpieces 10 can be selected.

Even when the workpiece 10 is gripped by the gripping claws 5 and pressed against a machine tool such as a grinder, a polishing machine, a cutting machine, or the like, the direction of the screw supporting the two gripping claws 5 provided on the same finger is processed. Are opposite to each other, the force for turning the screw is canceled out, and the gripping claws 5 do not move during the work.

The inside of the gripping claw 5 or the claw spacing variable mechanism 4
A spring may be provided in the inside of the device, a mounting portion of the variable claw spacing mechanism, or the like, so as to expand and contract. If such a mechanism is provided, the gripping claws 5 are pressed against the surface of the casting work 10 even when the unevenness and the gripping surface of the casting work 10 are not exactly parallel. Therefore, four points of the casting work can be reliably held.

FIG. 3 shows a state in which a spring is provided near the mounting portion of the gripping claw 5. This spring is provided inside a cylinder provided at the base of the gripping claw 5, and is held down by a piston 6. The piston 6 is of sufficient length in the cylinder, this part serving as a guide.
Thus, the gripping claws 5 do not shift in position even when an external force is applied from the side.

The variable gripping interval mechanism is not limited to the method shown in FIG. A rack is attached to the bottom of each gripping claw of each finger in parallel with the gripping claw operation direction, and each rack faces the opposite face. In the meantime, a pinion gear is provided so as to bite both racks, and the rack is moved by turning with a motor. At this time, since each rack moves in the opposite direction, the gap between the gripping claws can be adjusted.

A method is provided in which gripping claws are provided at both ends of an actuator for each finger, and the distance between the gripping claws is controlled by expanding and contracting the actuator. There is a method of controlling gripping claws separately.

FIG. 4 is a view for explaining an example of an automatic finishing system organized by using the work gripping mechanism of the present embodiment in an automatic grinding process for shaping a casting. The eight works 10 are sequentially conveyed by the belt conveyor 13,
The flowing work 10 is photographed by the video camera 14 when it comes to a fixed position. The video signal generated by the video camera 14 is sent to the image processing device 15, which checks the shape and mounting posture of the target work 10, the presence or absence of unevenness, the position of burrs, and the like. Based on the information, the position at which the gripping claws 5 are brought into contact with the work is determined, and the claw variable mechanism 4 adjusts the distance between the gripping claws 5 accordingly.

Then, the robot arm 16 moves to the position of the work 10 according to the information from the image processing device 15,
The work 10 is gripped by the robot hand 1. The robot arm 16 performs shaping by applying an unshaped part of the work 10 to the grinder 17 and moving the work up and down, rotating, holding, and the like. Note that when changing the holding position, the gripping claw interval is readjusted by the claw spacing variable mechanism 4 in accordance with the side length of the workpiece 10 to be newly gripped. When the shaping of the work 10 is completed, the robot arm 16 places the work 10 on the belt conveyor 13, finishes a series of operations, and adjusts the interval between the gripping claws toward the next work 10.

[0025]

As described above in detail, the work gripping mechanism of the present invention is used in a place where the robot hand handles the work in a labor-saving processing factory or the like, so that the work to be processed has various sizes and shapes. Even if the object has the above, the workpiece can be gripped with a sufficient gripping force without exchanging the finger according to the size of the workpiece and applied to a machine tool.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment of a work holding mechanism according to the present invention.

FIG. 2 is a drawing for explaining the operation of the work gripping mechanism of the present embodiment.

FIG. 3 is a drawing for explaining a mechanism according to an embodiment of a pawl spacing variable mechanism among the workpiece gripping mechanisms of the present invention.

FIG. 4 is a drawing for explaining an automatic grinding apparatus for shaping a casting by a robot hand incorporating a work gripping mechanism of the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Robot hand 2, 3 fingers 4 Claw spacing variable mechanism 5 Gripping claw 6 Piston 7 Feed screw 8 Motor 9 Gear 10 Cast work 11 Wide cast work 12 Narrow cast work 13 Belt conveyor 14 Video camera 15 Image processing device 16 Robot arm 17 grinder

──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Yasuhiro Komon 118 Notsuka, Noda-shi, Chiba Kawasaki Heavy Industries, Ltd. Noda Plant (72) Inventor Shutake Miki 118, Futatsuka, Noda-shi, Chiba Kawasaki Heavy Industries, Ltd. Inside the factory (56) References JP-A-5-293786 (JP, A) JP-A-4-14678 (JP, A) JP-A-4-82686 (JP, A) ) Actually open 49-49673 (JP, U) Actually open 63-91341 (JP, U) Actually open 62-174804 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B25J 15/08 B25J 13/08

Claims (5)

(57) [Claims] 1. A parallel facing two-piece having two gripping claws.
An opening / closing hand having two fingers , wherein the two gripping claws have a sharp edge toward the inside and have a structure capable of adjusting an interval on the finger , and a direction in which the fingers face each other.
The workpiece is moved with four gripping claws
A work gripping device characterized by being held down . 2. The work gripping device according to claim 1, wherein the gripping claw is attached to the opening / closing hand via an elastic body such as a spring. 3. An apparatus for photographing a workpiece and performing image processing, wherein the image processing apparatus measures a shape and a posture of the workpiece.
To the position shed gripping claws determined work gripping device according to claim 1 or 2, wherein the adjusting the spacing of the gripping claws. 4. The work gripping device according to claim 3, wherein the image processing device further checks irregularities and burrs of the work and determines a position where the gripping claw presses the work. 5. A work finishing device, comprising: a work handling device to which the work gripping device according to claim 1 is attached; and a work finishing device, wherein the work handling device automatically grips the work and the work finishing device. An automatic finishing system that performs finishing work by pressing a workpiece onto a workpiece.