JPH07266276A - Work holding device - Google Patents

Abstract

PURPOSE:To enable conveyed workpieces to be released and to enable plural kinds of workpieces of different sizes to be held by one device by sucking each workpiece in the correct position while employing a structure in which the workpieces are held by means of the magnetic force of a permanent magnet for miniaturization of a hand portion and powder savings. CONSTITUTION:A fixed finger 11 is fixed to a hand and a movable finger 13 is rotatably supported on the hand, and a fixed side metallic plate 15 and a movable side metallic plate 18 both of which can be magnetized are secured, respectively, to the inner surfaces of the fingers 11, 13, and a permanent magnet 20 is abutted and secured to the inner surface of the movable side metallic plate 18 and an air cylinder 30 is provided which rotates the movable finger 13 within a range from a closed position at which the permanent magnet 20 abuts the fixed side metallic plate 15 to an enlarged position at the distance at which no magnetic force is applied to the fixed side metallic plate 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small work, which is provided in a hand of a robot, and particularly for holding a small work formed of a magnetic material such as a balance weight of a tire one by one. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, as a device for adsorbing and conveying a work w by utilizing a magnetic force to convey a small work w, for example, a device described in Japanese Utility Model Publication No. 4-2788 is known. Has been. This conventional technique will be described with reference to FIG. 6. At the tip of the robot hand 100 (not shown),
A work holding device 101 that holds the work w is provided. This work holding device 101 has a right finger 102 and a left finger 1 that extend in parallel with a predetermined interval.
03, and a finger 104 that is vertically slidable and rotatable back and forth is provided at the tips of both fingers 102 and 103. The finger 104 has claws 105 extending in the work w direction. 106 are formed. The magnetic force of the electromagnet 107 acts on the pad 104 and the claws 105 and 106, and the work w is adsorbed and conveyed by the tip end surfaces of these.

[0003]

However, in this structure, since the electromagnet is used, the hand 100 becomes large in size, and power for moving the large-sized hand 100 and enormous electric power for operating the electromagnet are required. It was something that became.

Therefore, it is conceivable to use a permanent magnet instead of the electromagnet, but in the case of a permanent magnet, it is difficult to separate the work w, and the posture of the work w tends to be disturbed at the time of separation.
It is very difficult to control the magnetic force. That is, since the magnetic force of the permanent magnet is constant, a means for fixing the work w is required when the work w that has been once attracted is released, which leads to an increase in the size of the apparatus. If the magnetic force is too strong, the work w may be attracted just by bringing the magnet close to the work w, and the posture may be disturbed when the work w moves in the space separated from the work w. If it is weak, the above-mentioned disorder of the posture is hard to occur, but there is a possibility that the work w cannot be attracted or the work w falls while being held by a magnet.

Further, in the prior art, since the holding force depends only on the electromagnet, when the works w having different sizes are conveyed, a plurality of kinds of the backing pads 104 and the claws corresponding to the shapes of the respective works w are carried. 105 and 106 must be prepared, and each time the work w changes, these must be replaced and used according to the work w, and the replacement work and wiring were very complicated.

The present invention has been made by paying attention to such problems of the prior art, and adopts a structure in which a magnetic force of a permanent magnet holds a work in order to reduce the size of the hand and save power. The object of the present invention is to adsorb a work piece in an accurate posture, to facilitate the separation of the work piece after conveyance, and to allow a single device to hold a plurality of work pieces of different sizes.

[0007]

In order to achieve the above-mentioned object, according to the present invention, two fingers are provided at the tip of the hand of a robot with their inner side surfaces facing each other, and a magnetic force is applied to the fingers to cause the fingers to move. In the work holding device for sucking and holding the work at the tip of the hand, the two fingers are fixed fingers protruding from the tip of the hand and fixed to the hand, and from a position close to the fixed finger to a position distant from the fixed finger. A movable side metal plate and a fixed side metal plate, which are formed of magnetizable metal, are fixed to the inner side surface of each finger, respectively. A permanent magnet is fixed to the inner surface of the stationary finger in a contact state, and the permanent magnet is magnetically attached to the fixed side metal plate from the closed position where the permanent magnet contacts the fixed side metal plate. Actuators for rotating within the range up to expanded position spaced apart a distance which does not give has a configuration provided.

A contact surface having a shape capable of surface contact with the work may be formed at the tip of each metal plate.

Further, at the tip of each of the fingers, there is provided a claw portion formed to have a shape capable of holding a work in a state where the movable finger is arranged at the closed position, and the claw portion is formed so as to be elastically deformable. Good.

[0010]

[Operation] The operation for holding the work will be described step by step. First, the actuator moves the movable side finger to the expanded position to widen the gap between both fingers.
Then, in this state, the robot moves the hand,
The tip of the fixed side metal plate is pressed against the work to hold and fix the work. In the state where the movable side fingers are arranged in the expanded position, the magnetic force of the permanent magnet does not act on the fixed side metal plate pressed against the work, and the magnetic force is generated immediately before the fixed side metal plate is pressed. The problem that the work moves does not occur. Further, according to the second aspect of the present invention, the pressing of the work brings the contact surface of the fixed side metal plate into contact along the shape of the work.

Next, when the movable finger is rotated in the closing position direction by the actuator from the pressed state of the work, the permanent magnet provided inside the movable finger comes into contact with the fixed metal plate, and the permanent magnet is removed. , It is sandwiched between the movable side metal plate and the fixed side metal plate. In this state, the magnetic field of the permanent magnet goes around both metal plates, magnetizes both the movable side metal plate and the fixed side metal plate to increase the overall magnetic force, and the workpiece is attracted by this increased magnetic force. It will be in a state of being. In the apparatus according to claim 2, at this time, the contact surface of the movable side metal plate abuts along the shape of the work, and in the apparatus according to claim 3, the claw portion at the tip of each finger works. Further, when the size of the work is different, the claw portion elastically deforms to absorb the size difference.

As described above, due to the attractive force of the magnetic force,
According to the third aspect, when the work is held by nipping the claws, the robot moves the hand to convey the work to a predetermined position.

After the work has been conveyed in this way, when the work is to be released, the work is kept stationary by pressing the work from above with at least the fixed-side metal plates of both metal plates based on the movement of the robot. After that, when the actuator is driven to rotate the movable side finger in the expanded position direction, the permanent magnet is separated from the fixed side metal plate, the fixed side metal plate is demagnetized, and the attraction force to the work disappears. Further, in the apparatus according to the third aspect, the holding state by the claw portion is also released.

In this state, when the robot raises the entire hand, it is separated from the work.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. In the present embodiment, as shown in FIG. 2, the driving device for driving the balance weight W of the tire (corresponding to the work in the claims and hereinafter referred to as weight) from the supply device A to the wheel. A hand H of a four-axis orthogonal transfer robot D for transferring to the driving worktable C of B
The case of application to is explained.

Here, the weight W will be explained. The weight W is attached to the outer circumference of the wheel of the tire so that the center of gravity of the tire coincides with the center of rotation, and is shown in (a) and (b) of FIG. So that the weight W1 made of lead material hooks on the wheel W2
Is integrally formed, and the clip W2 is made of an iron material attracted by a magnet. As the weight W, a plurality of types of weight W1 having different weights W1 and different lengths a and widths b of the clip W2 are set.

Returning to FIG. 2, the feeder A is composed of a plurality of bowl feeders F which sort the weights W by type and feed them to the rails R, and the tips of the rails R are gathered at one place.

The transfer robot D is installed at a position where the rails R are collected. This transfer robot D
Is an up-down axis for raising and lowering the hand H, the hand H
It is a well-known robot that is equipped with two horizontal movement axes that are orthogonal to the horizontal direction and four rotation axes that rotate the hand H around the vertical axis, and that is called a four-axis orthogonal type robot. Is.

Below the transfer robot D, a pedestal E formed to hold the weight W is provided, and the transfer robot D receives the arbitrary weight W from the supply position A from the pedestal. Carry work to E.

The pedestal E is provided so as to be movable up and down, the driving work table C is installed next to the position where the pedestal E is lowered, and the driving device B is next to it. Is installed.

The work holding device 1 of the embodiment of the present invention is attached to the tip of the hand H of the transfer robot D.
The details of the work holding device 1 will be described with reference to FIG.
A seat member 1a made of steel is attached to the tip of the hand H, and the spring steel 1 is provided below the four corners of the seat member 1a.
The base portion 1c is floatingly supported with b interposed. The base 1c is made of aluminum as a material and is formed into a substantially L shape.

The fixed finger 1 is attached to the tip of the base 1c.
1 is fixed by a screw 12, and a movable finger 13 is rotatably supported so that the fixed finger 11 and inner side surfaces face each other. That is, the movable finger 13 is provided with a bracket 13b on the upper portion of the finger body 13a so as to form a substantially T shape, and one end of the bracket 13b is rotatably supported by the base 1c. A piston rod 30 of an air cylinder 30 as an actuator is provided at the other end of the bracket 13b.
a is connected via a link 30b, and by driving the air cylinder 30, the movable finger 13 approaches the fixed finger 11 about the rotation center Z (hereinafter, this operation is closed) and is separated. It is configured to rotate (hereinafter, this operation is expanded).

At the tip of the fixed finger 11, there is provided a fixed side claw member 14 as a claw portion formed of stainless steel which is not magnetized so as to be elastically deformable like a leaf spring, and inside the fixed side claw member 14. The fixed side metal plate 15 made of iron, which is disposed and magnetizable, is fixed by screws 16 in a state of being overlapped.

The finger body 13 of the movable finger 13
A movable side claw member 17 as a claw portion formed of stainless steel so as to be elastically deformable into a leaf spring, and a metal magnetizable inside the movable side claw member 17 are formed in a. The movable metal plate 18 and the movable metal plate 18 are fixed to each other with screws 19. Further, the permanent magnet 20 is fixed by surface-contacting the inside of the movable side metal plate 18, and the movable side metal plate 18 is always magnetized. The fixed side claw member 14 has a shape in which the tip is slightly bent inward as shown in the figure, while the movable side claw member 17 has a shape in which the movable side claw member 17 bulges outward and is then bent inward. Has been formed. Further, as shown in the drawing, the permanent magnets 20 are arranged in a positional relationship of abutting against the fixed side metal plate 15 when the movable side metal plate 18 is rotated in the closing direction, and the abutting position thereof. Is arranged so that the center in the thickness direction (horizontal direction in the drawing) coincides with the center in the thickness direction (horizontal direction in the drawing) of the fixed finger 11. Further, curved contact surfaces 15a and 18a, which substantially match the shape of the clip W2 of the weight W, are formed at the lower ends of the metal plates 15 and 18, respectively. further,
A photoelectric sensor 21 for detecting whether or not the weight W is held is provided outside the fixed finger 11.
That is, driving of the actuators such as the motor of the transfer robot D and the air cylinder 30 of the apparatus of this embodiment is controlled by a computer (not shown), and the photoelectric sensor 21 is provided as one of the input means of this computer. ing.

Next, the operation of the embodiment apparatus will be described. As described above, the transfer robot D is for transferring the weight W from the supply device A to the pedestal E, and first holds the hand H to hold the weight W sent by the rail R of the supply device A. To the upper position of the rail R. That is, the optimum size of the clip W2 corresponding to the wheel of the tire set on the driving work table C is input in advance, and the optimum weight is determined by a test by a tire balancer (not shown) performed in advance. , The transfer robot D, among the plurality of rails R of the supply device A,
The hand H is moved to a position above the rail R to which the optimum weight W is sent.

Next, the air cylinder 30 is driven to rotate the movable finger 13 in the expanding direction, and as shown in FIG. The hand H is lowered by the operation of the robot D, and the contact surface 15a at the tip of the fixed-side metal plate 15 is pressed against the curved portion of the upper portion of the clip W2 of the weight W supported by the rail R, and the weight W is railed. Fix with respect to R. At this time, the fixed-side metal plate 15 is not magnetized because it is separated from the permanent magnet 20, and when the fixed-side metal plate 15 is brought close to the weight W, an attractive force acts on the weight W to change its direction. The posture of the weight W is stable without any trouble.

Next, when the air cylinder 30 is driven from this state to rotate the movable finger 13 in the closing direction, this rotation causes the permanent magnet 20 provided inside the movable finger 13 to move to the permanent magnet 20 shown in FIG. As shown in FIG. 7, the movable side metal plate 18 and the fixed side metal plate 15 are sandwiched, and the clip W2 is sandwiched between both the claw members 14 and 17, and the weight W is held by the holding device 1. It is held and conveyed by the attraction force by the magnetic force of ## EQU1 ## and the clamping force by both claw members 14 and 17. In addition, both metal plates 15 and 18 as described above.
In the sandwiched state of the permanent magnet 20 by the magnetic field, a magnetic field is generated around both metal plates 15, 18 as shown in FIG.
8 is magnetized, and the magnetic flux density is further increased to increase the magnetic force.

When the weight W is held as described above and the width dimension b of the clip W2 of the weight W is larger than that shown in the drawing, the time when the fixed side metal plate 15 is brought into contact with the clip W2. While the fixed side claw member 14 elastically deforms outward (see the imaginary line in FIG. 3B), when the movable side finger 13 is closed, the movable side claw member 17 flexes outward and elastically deforms. The elastic force of the members 14 and 17 increases the clamping force, and this elastic deformation allows different sizes to be accommodated.

After holding the weight W as described above, the transfer robot D is then driven to move the hand H upward once to lift the weight W from the rail R, and then the hand H is received on the pedestal E. Down to the height of. That is, similarly to the rail R, the receiving base E is provided with a receiving portion (not shown) formed so that the clip W2 of the weight W can be engaged, and the weight W is engaged with this receiving portion. The hand H is lowered and horizontally moved or rotated so that Note that, when the weight W is not detected by the photoelectric sensor 21 when the hand H is moved upward, the above work is performed again.

When the weight W is moved to the predetermined position in this way, the weight W is separated from the apparatus 1 of the present embodiment. First, the air cylinder 30 is driven to move the movable side finger 13 in the expanding direction. This allows the permanent magnet 2
0 separates from the fixed side metal plate 15 and the magnetization of the fixed side metal plate 15 is released. Therefore, the suction force to the weight W is lost, and when the hand H is raised in this state, the fixed-side metal plate 15 separates from the weight W.

As described below, according to the work holding device 1 of this embodiment, since the permanent magnet 20 attracts the magnetic force of the weight W, the device is smaller than the case where the electromagnet is used. In addition, it is possible to obtain the effect that energy saving can be achieved because electric power is unnecessary.

In addition, although the permanent magnet 20 is used for attraction, the movable finger 1 for supporting the permanent magnet 20 is used.
3 is made rotatable, and only the fixed-side metal plate 15 that is not magnetized and has no attractive force is brought into contact with the weight W at the initial stage of the holding operation and when the weight W is separated. The weight W does not change the posture of the weight W or cannot be separated due to the suction force during operation and separation.
It is possible to obtain the effect that the posture can be always kept constant, and the reliability and work efficiency that are the same as those when using the electromagnet while using the permanent magnet 20 can be obtained.

Further, when the weight W is attracted, the permanent magnet 20 is sandwiched between the movable side metal plate 18 and the fixed side metal plate 15, so that the magnetic flux density is large and large as compared with the case where only the permanent magnet 20 is attracted. The effect that suction power is obtained is obtained.

Furthermore, at the tips of both metal plates 15 and 18,
Since the curved contact surfaces 15a and 18a that are in surface contact with the clip W2 of the weight W are formed, the posture of the weight W is stabilized during suction. in addition,
Since the claw members 14 and 17 having elasticity are provided at the tips of the fingers 11 and 13, respectively, when the weight W is held, the claw members 1 and 13 are depending on the size of the weight W.
4, 17 are elastically deformed to hold weights W of different sizes, and the effect that one device can hold a plurality of types of weights W is obtained, and the claw member 1
When 4 and 17 are elastically deformed, the restoring force acts so as to sandwich the weight W, and the holding force can be improved.

Although the embodiment of the present invention has been described above with reference to the drawings, the specific configuration is not limited to this embodiment, and even if there is a design change or the like without departing from the scope of the present invention. Included in the present invention.

For example, although the present embodiment is applied to the hand H of the orthogonal four-axis type transfer robot D, it may be applied to any type of robot as long as it has the hand H for moving the apparatus of the present invention. You may.

In the present embodiment, the tire balance weight W is shown as the work, but if the weight is such that it can be attracted by the magnetic force of the permanent magnet, it can be used when carrying other works such as bolts and nuts. May be.

Although iron is used as the material of the fixed side metal plate 15 and the movable side metal plate 18 in the embodiment, other materials such as nickel may be used as long as it is a magnetizable metal.

Although the fixed side claw member 14 and the movable side claw member 17 are made of stainless steel that is not magnetized, other metals or resins may be used as long as they have a predetermined elasticity.

In the embodiment, the claw members 14 and 17 which are separate from the fingers 11 and 13 are provided as the claws, but the claws are essentially elastically deformable to the fingers 1.
It suffices if it is provided at the tip portions of 1 and 13, and it may be formed integrally with each finger itself.

[0041]

As described above, in the present invention, the movable side metal plate and the fixed side metal plate of magnetizable metal are fixed to the inner side surface of each finger, and the inner side surface of the movable side metal plate is fixed. Within the range from the closed position where the permanent magnet is fixed and the actuator moves the movable finger from the closed position where the permanent magnet abuts the fixed side metal plate to the expanded position where the permanent magnet is separated by a distance that does not apply magnetic force to the fixed side metal plate. Since it is configured to rotate, it is possible to reduce the size of the device as compared with the structure in which the magnetic force of the electromagnet is used for attraction, and it is possible to obtain the effect that energy can be saved without consuming electric power. When the work is attracted, the permanent magnets are sandwiched between the metal plates, so that the magnetic force can be increased, and a large attraction force can be obtained with a small permanent magnet. In addition, by rotating the movable finger within the range from the closed position to the expanded position, the work is sucked while the fixed-side metal plate is kept in contact with the work even though the structure uses permanent magnets. It is possible to switch between the state where the workpiece is held and the state where it is not sucked, so that when the workpiece is held and released, the workpiece does not move due to the suction force, and the workpiece is always kept in a normal posture. The effect of being able to do is obtained.

Further, in the apparatus according to the second aspect of the invention, since the abutting surfaces formed so as to be able to come into surface contact with the work are formed at the tips of both metal plates, when the work is pressed, High retention performance is obtained when sucked.

Further, in the apparatus according to the third aspect, since the elastically deformable claw portions are provided at the tips of both fingers and the work is clamped by the claw portions, the effect of improving the work holding performance can be obtained. In addition, even when there are multiple types of work sizes, when holding the work, both claws can elastically deform according to the size of the work and clamp the work, and one device can handle multiple types of sizes. The effect of being able to hold the work of is obtained.

[Brief description of drawings]

FIG. 1 is a side view showing a work holding device according to an embodiment of the present invention.

FIG. 2 is an overall view showing an applied state of the apparatus of the embodiment.

FIG. 3 is an explanatory diagram of the operation of the apparatus of the embodiment.

FIG. 4 is an explanatory diagram showing the operation of the apparatus of the embodiment.

5 (a) is a side view and FIG. 5 (b) is a cross-sectional view showing a clip held by the apparatus of the embodiment.

FIG. 6 is a perspective view showing a conventional work holding device.

[Explanation of symbols]

 1 Work Holding Device 11 Fixed Finger 13 Movable Finger 14 Fixed Side Claw Member (Claw) 15 Fixed Side Metal Plate 15a Abutment Surface 17 Movable Side Claw Member (Claw) 18 Movable Side Metal Plate 18a Abutment Surface 20 Permanent Magnet 30 Air cylinder (actuator)

Claims (3)

[Claims] 1. A work holding device in which two fingers are provided at the tip of a hand of a robot with their inner surfaces facing each other, and a magnetic force is applied to the fingers to suck and hold the work at the tip of the finger. Each finger is composed of a fixed finger protruding from the tip of the hand and fixed to the hand, and a movable finger rotatably supported from a position close to the fixed finger to a position apart from the fixed finger. The movable side metal plate and the fixed side metal plate formed of magnetizable metal are fixed to the inner side surfaces thereof, and the permanent magnet is fixed in contact with the inner side surface of the movable side metal plate, Rotate the movable finger within a range from a closed position where the permanent magnet abuts the fixed side metal plate to an expanded position where the permanent magnet is separated by a distance that does not apply magnetic force to the fixed side metal plate. Workpiece holding device, characterized in that actuator for is provided. 2. The work holding device according to claim 2, wherein a contact surface having a shape capable of surface contact with the work is formed at a tip portion of each of the metal plates. 3. Each of the fingers is provided with a claw portion formed in a shape capable of holding a work with the movable finger arranged in a closed position, and each claw portion is elastically deformable. The work holding device according to claim 1 or 2, characterized in that.