JPH0512115B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a gripper for a robot, and more specifically, to a gripper for a robot, and more specifically, a gripper for gripping a workpiece with a finger using a pressurized fluid such as pressurized oil or compressed air. This invention relates to a gripper for a robot that is designed to be used for gripping.

[Conventional technology]

Conventional grippers for robots of this type have a pair of fingers facing each other on the left and right sides of the main body, and both the left and right fingers are connected to a piston provided inside the main body, and the piston is moved by pressurized fluid. Accordingly, the distance between the two fingers is changed so that the grip can be grasped.

[Problem to be solved by the invention]

However, conventional grippers do not have an automatic adjustment function for the left and right fingers, and both fingers move at the same speed, so the center of the robot hand and the center of the workpiece to be gripped are misaligned. In many cases, an excessive force is applied to the finger that comes into contact with the workpiece first, and unreasonable force is often applied to the joints of the robot, the workpiece, etc.

Therefore, the purpose of this invention is to enable each finger to press the workpiece with equal force even if the center of the robot hand and the center of the workpiece are misaligned.
To provide a gripper for a robot that does not cause damage to a workpiece or a robot.

[Means to solve the problem]

In order to achieve the above object, the present invention takes the following technical measures.

That is, a gripper main body 2, a pair of fingers 3a, 3b provided on both sides of the gripper main body 2 facing each other, and each of the fingers 3a, 3 provided inside the gripper main body 2.
The robot is equipped with a pair of cylinders 6a and 6b for driving the robot, and is configured to supply and discharge pressurized fluid to and from the cylinders 6a and 6b, and grip the workpiece 9 with the fingers 3a and 3b. In the gripper for use, the pair of cylinders 6a, 6b
Supply channel 12a, 1 for supplying pressurized fluid to
2b and discharge channels 16a, 16b for discharging the pressurized fluid in the pair of cylinders 6a, 6b.
The adjustment valve 18 continues in the middle of the process.

The regulating valve 18 has a spool 20 movably provided inside a cavity 19 formed in the gripper main body 2, and the pair of cylinders 6a,
The spool 20 has a pair of pilot chambers 26a and 26b that communicate with the grip side chambers 13a and 13b of the spool 6b, respectively, and the spool 20 is moved by the pressure difference between the pressurized fluids in the pilot chambers 26a and 26b. It is configured as follows.

When the spool 20 is in the center position,
The supply of pressurized fluid to each cylinder 6a, 6b and the discharge of pressurized fluid from each cylinder 6a, 6b through the regulating valve 18 are performed so that each finger 3a, 3b moves in the same manner. When the spool 20 is moved away from the center position, the cylinder (6a or 6) that drives the finger (3a or 3b) whose movement was previously prevented is
b) the amount of pressurized fluid supplied to and the amount of pressurized fluid discharged from the cylinder (6a or 6b) decreases, and the other finger (3a or 3b)
The amount of pressurized fluid discharged from the cylinder (6a or 6b) that drives the cylinder is increased.

The spool 20 includes piston portions 23a, 23b provided at both ends, and piston portions 23a, 23b provided at both ends.
Two large diameter parts 25 arranged at equal intervals between 3b
a, 25b, and three small diameter portions 24a, 24b, 24c formed between the large diameter portions 25a, 25b and the piston portions 23a, 23b. In this case, each of the supply channels 12
a, 12b are the small diameter portions 24a, 24b, 24
are connected to each other through the outer two small diameter portions 24a and 24b of c, and each of the discharge flow paths 16
a and 16b are connected to each other through annular grooves formed in the large diameter portions 25a and 25b.

The regulating valve 18 can be provided with yet another discharge passage 22 . The discharge channel 22
is preferably connected around the central small diameter portion 24c among the small diameter portions 24a, 24b, and 24c, and has a large flow passage cross-sectional area.

Further, when the spool 20 is removed from the center position, the pressurized fluid is applied to the cylinder (6a or 6a) on the finger (3a or 3b) side that contacted the work 9 first
or 6b) on the gripping side chamber (13a or 13
b) and a separate chamber (15a or 15b).

[Effect]

While both fingers 3a, 3b are moving at a constant speed, pressurized fluid of the same pressure is supplied to both pilot chambers 26a, 26b via pilot pressure supply channels 21a, 21b, so that the spool 20 is kept in a central position. In this state, both fingers 3
a and 3b move at the same speed.

When one finger, for example, the right finger 3a, is first prevented from moving by the workpiece 9, the pressure in the grip side chamber 13a of the cylinder 6a that drives the finger 3a increases temporarily.
The pressure in the pilot chamber 26a of the regulating valve 18 that communicates with the chamber 13a is the pilot chamber 26b on the opposite side.
higher than the internal pressure. As a result, spool 2
0 is pushed toward the left and moves to the left from the center position. In this state, the amount of pressurized fluid supplied to the chamber 13a on the grip side of the cylinder 6a is throttled, and at the same time the amount of fluid discharged from the chamber 15a on the release side is also throttled, so that the pressure in both chambers 13a, 15a is reduced. become equal within a short time, and the above finger 3a
movement will be stopped immediately.

On the other hand, the finger 3b on the side whose movement is not hindered by the workpiece 9 continues to be supplied with pressurized fluid to the chamber 13b on the grasping side as before, and the fluid in the chamber 15b on the releasing side continues to be supplied. Since it is rapidly discharged, the finger 3a can move at a faster speed than before contacting the workpiece 9, and can contact the workpiece 9 in a short time.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 and 2, a gripper 1 for a robot according to the present invention is configured with a pair of left and right fingers 3a, 3b facing each other on the outside of a gripper body 2. Both fingers 3a, 3b are supported by support shafts 4a,
The support shafts 4a and 4b are attached to the gripper body 2 so as to be movable left and right by the support shafts 4a and 4b.
Both support shafts 4a and 4b are supported via bearings 5 fixed to the gripper body 2 in order to allow smooth sliding.

Furthermore, a pair of cylinders 6a and 6b for driving the fingers 3a and 3b are provided in the gripper body 2, and a rod 7 of each cylinder 6a and 6b is provided.
The tips of a and 7b are connected to each finger 3a and 3b. Therefore, when the pistons 8a, 8b of the cylinders 6a, 6b move due to the supply and discharge of pressurized fluid, the fingers 3a, 3b are thereby moved.
can move left and right and can grip and release the workpiece 9.

10 and 11 are a supply port and a discharge port for pressurized fluid, and the supply port 10 is connected to the supply flow path 12c.
and two supply channels 1 branched from the supply channel 12c.
The cylinders 2a and 12b communicate with the outer grip side chambers 13a and 13b of each cylinder 6a and 6b. Further, the discharge port 11 has a discharge flow path 14,
Two discharge channels 16 merging with the discharge channel 14
It communicates with chambers 15a, 15b on the inner side and away from each cylinder 6a, 6b via a, 16b.
Orifices 17 are provided at the ends of the discharge channels 16a and 16b on the discharge port 11 side, respectively, to restrict the discharge amount of the pressurized fluid and gradually move the pistons 8a and 8b.

Inside the gripper body 2, a regulating valve 18 is further provided between the supply channels 12a, 12b and the discharge channels 16a, 16b. This adjustment valve 18 is
A spool 20 is slidably fitted inside a cylindrical cavity 19 formed in the gripper body 2, and when the forces applied to the left and right fingers 3a and 3b are not the same, the movement is adjusted and the two fingers The fingers 3a and 3b serve to grip the workpiece 9 with equal force.

At the left and right ends of the cavity 19 are cylinders 6
A pair of pilot pressure supply passages 21a, 21 communicating with the grip side chambers 13a, 13b of a, 6b, respectively.
b is connected to the cavity 19, and another discharge passage 22 penetrating the discharge passage 14 is connected to the center of the cavity 19. This discharge flow path 22 includes
Since the orifice 17 provided in the discharge channels 16a and 16b is not provided, the discharge channel 1
It has a flow passage cross-sectional area considerably larger than that of 6a and 16b.

The spool 20 has a symmetrical shape,
It has cylindrical piston parts 23a and 23b that slide on the inner wall surface of the cavity 19 at both left and right ends. Further, two small diameter portions 24a, 24b are formed adjacent to each piston portion 23a, 23b, and two large diameter portions 25a, 25b are formed adjacent to each small diameter portion 24a, 24b. . A small diameter portion 24c is further formed between the large diameter portions 25a and 25b, that is, at the center of the spool 20.
The two large diameter portions 25a, 25b are at equal distances from the piston portions 23a, 23b. Since there is a fairly large gap between the three small diameter portions 24a, 24b, 24c and the inner wall surface of the cavity 19,
Pressurized fluid can flow through this gap. In addition, each of the two large diameter portions 25a and 25b has a depression formed in the center and both ends are flanged, so that the flanged ends slide on the inner wall surface of the cavity 19. The pressurized fluid flows through the depression and cavity 1 in the center.
It is possible to flow through the annular groove formed between the inner wall surface of 9 and the inner wall surface of 9.

Note that the flanged ends of the piston portions 23a, 23b and the large diameter portions 25a, 25b are connected to the cavity 19.
Because they are in close contact with the inner wall of the cavity 19, the flow of the pressurized fluid in the left-right direction, that is, in the longitudinal direction of the cavity 19, is almost impeded by these parts, and the two spaces adjacent to each other are almost completely cut off.

The spool 20 is normally located at the center position as shown in FIG. They pass through each other through a gap around 24b. Similarly, the upper and lower portions of the two discharge channels 16a and 16b are both connected to the two large diameter portions 24.
a, 24b are connected to each other via annular grooves, and the other discharge flow path 22 is connected to the central small diameter portion 24.
It leads to the gap around c.

The adjustment valve 18 changes the connection state of each flow path as described later when the spool 20 moves in either the left or right direction, and automatically adjusts the moving speed of the fingers 3a, 3b.

Next, the operating state of the gripper 1 configured as above will be explained.

When gripping the workpiece 9 with both fingers 3a and 3b, pressurized fluid such as pressurized oil or compressed air is supplied from the supply port 10 and also from the discharge port 11.
This pressurized fluid is discharged from the supply channel 12
c and supply channels 12a, 12 branched from it
It flows into the regulating valve 18 through the upper part of b.

Within regulating valve 18, spool 20 typically
As shown in the figure, the supply channel 12 is in the central position.
The upper and lower parts of a and 12b are connected to the spool 2.
Since the small diameter portions 24a and 24b on the left and right side of the cylinder 0 communicate with each other through a gap around the small diameter portions 24a and 24b, the pressurized fluid further flows into the grip side chambers 13a and 24b of each cylinder 6a and 6b.
13b. In addition, the discharge channels 16a, 16
The upper and lower portions of b communicate with each other via the annular grooves of the two large diameter portions 25a and 25b of the spool 20, so that at the same time as the supply, each cylinder 6
The pressurized fluid in 15a, 15b on the separated side of a, 6b is discharged to the outside from the discharge port 11 through the discharge channels 16a, 16b and the discharge channel 14 where they merge. At this time, the fluid is squeezed by the orifice 17 and gradually discharged, so
Both fingers 3a, 3b gradually move inward.

When both fingers 3a, 3b are moving at approximately constant speed, the pilot pressure supply channel 21 is supplied from the grip side chambers 13a, 13b of each cylinder 6a, 6b.
Since the pilot pressures sent to the left and right pilot chambers 26a, 26b of the spool 20 of the regulating valve 18 via a, 21b are approximately the same pressure, the spool 2
0 keeps the center position.

Next, since the center of the workpiece 9 to be gripped is misaligned with the center of the gripper 1, if only the right finger 3a comes into contact with the workpiece 9 first, the spool 20 will move to the left side as shown in FIG. Moving. This is because the movement of the right finger 3a is the workpiece 9.
, the pressure in the grip side chamber 13a of the right cylinder 6a becomes temporarily high due to the influence of the back pressure. The pressure in the pilot chamber 26a on the right side of the regulating valve 18, which communicates with the regulator valve 13a, also increases. On the other hand, since the left finger 3b continues to move, the above-mentioned back pressure does not occur. This is because a difference occurs in the pressures acting on the piston portions 23a and 23b of the spool 20, and the spool 20 is pushed to the left by this pressure difference.

In the state shown in FIG. 2, the supply flow path 12a on the right side is constricted by the piston portion 23a on the right side, so that the amount of pressurized fluid supplied to the grip side chamber 13a of the cylinder 6a on the right side decreases. At the same time, the amount of pressurized fluid discharged from the chamber 15a on the remote side is also throttled by the large diameter portion 25a on the right side of the spool 20, resulting in a considerable reduction in the amount of discharged fluid. In this state, a portion of the pressurized fluid also flows through the supply channel 12a.
Since it flows into both chambers 13a, 15a through the lower part and the lower part of the discharge flow path 16a, the pressures in both chambers 13a, 15a become equal in a short time.
Since there is no force to move the finger 3a inward, the finger 3a is held in that position.

In the left cylinder 3b, the supply flow path 12b is not constricted by the spool 20, so the amount of pressurized fluid supplied to the gripping side chamber 13b does not change. On the other hand, the pressurized fluid in the chamber 15b on the remote side is discharged through the lower part of the discharge passage 16b through the annular groove of the left large diameter part 25b and around the small diameter part 24c in the center. Since it communicates with the upper part of the channel 16b and the central discharge channel 22, the discharge amount is greatly increased. In particular, since the orifice 17 is not provided and the liquid is discharged through the central discharge passage 22 which has a large cross-sectional area, the discharge amount becomes very large. Therefore, the left finger 3b moves at a much faster speed than the right finger 3a before it comes into contact with the workpiece 9.

When the finger 3b comes into contact with the workpiece 9, both piston portions 23 of the spool 20 are moved as described above for the right finger 3a.
Since there is a difference in the forces acting on a and 23b, the spool 20 moves to the right, and eventually the pressures are balanced and the spool 20 returns to the center position. In this way, the workpiece 9 is pressed and gripped by both fingers 3a and 3b with equal force.

When releasing the gripped workpiece 9, pressurized fluid may be supplied from the discharge port 11 and discharged from the supply port 10, contrary to the above. In this way, the pistons 8a and 8a of each cylinder 6a and 6b are moved by the pressurized fluid.
8b is moved outward, and both fingers 3
Since a and 3b are separated from each other, the workpiece 9 can be separated.

〔Effect of the invention〕

As is clear from the above description, the gripper 1 according to the present invention automatically moves both fingers 3 even if the center of the gripper 1 and the center of the workpiece 9 are misaligned.
The moving speeds of a and 3b are adjusted so that both fingers 3
A and 3b have excellent effects such as being able to grip the workpiece 9 with equal force, preventing damage to the workpiece 9 or the robot by applying excessive force, and having a simple configuration.

In addition, another discharge passage 2 is connected to the regulating valve 18.
2, the cross-sectional area of the discharge flow path becomes very large, and the finger 3b or 3a on the side that does not contact the workpiece 9 can be quickly moved and brought into contact with the workpiece 9.

Further, when the spool 20 is removed from the center position, the pressurized fluid is transferred to the grasp side chamber 13a or 13b of the cylinder 6a or 6b on the side of the finger 3a or 3b that contacted the workpiece 9 first, and to the release side chamber. When configured to be supplied to the finger 3a or 15b, it is possible to quickly stop the finger 3a or 3b and shorten the time during which excessive force is applied to the workpiece 9 or the robot.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view showing one embodiment of a gripper for a robot according to the present invention. Figure 2 shows
FIG. 3 is an enlarged cross-sectional explanatory diagram of the regulating valve showing a state when the spool is moved to the left side. 1... Gripper for robot, 2... Gripper body, 3a, 3b... Finger, 6a, 6b...
Cylinder, 7a, 7b... Cylinder rod, 8
a, 8b... Cylinder piston, 9... Work, 10... Supply port, 11... Discharge port,
12a, 12b, 12c... supply channel, 13a,
13b...Gripping side chamber, 14, 16a, 16b,
22... Discharge flow path, 15a, 15b... Release side chamber, 17... Orifice, 18... Regulating valve, 19
...Cavity, 20...Spool, 21a, 21b...
...Pilot pressure supply channel, 23a, 23b...
Piston part, 24a, 24b, 24c...Small diameter part, 25a, 25b...Large diameter part, 26a, 26b
...Pilot room.

Claims (1)

[Scope of Claims] 1. A gripper main body 2, a pair of fingers 3a and 3b provided on both sides of the gripper main body 2 facing each other, and the gripper main body 2.
A pair of cylinders 6a and 6b provided inside the cylinder for driving the fingers 3a and 3b,
In a robot gripper configured to supply and discharge pressurized fluid to the cylinders 6a, 6b and grip the workpiece 9 with the fingers 3a, 3b, the pressurized fluid is supplied to the pair of cylinders 6a, 6b. A regulating valve 18 is provided in the middle of the supply channel 12a, 12b for supplying the fluid and the discharge channel 16a, 16b for discharging the pressurized fluid in the pair of cylinders 6a, 6b. , a spool 20 is movably provided inside a cavity 19 formed in the gripper main body 2, and the pair of cylinders 6a,
The spool 20 has a pair of pilot chambers 26a and 26b that communicate with the grip side chambers 13a and 13b of the spool 6b, respectively, and the spool 20 is moved by the pressure difference between the pressurized fluids in the pilot chambers 26a and 26b. Moreover, when the spool 20 is at the center position, the pressurized fluid is supplied to the cylinders 6a, 6b through the regulating valve 18, and the pressurized fluid is supplied from the cylinders 6a, 6b. The pressurized fluid is discharged so that each of the fingers 3a and 3b moves in the same way, and when the spool 20 moves away from the center position, the finger (3a or 3b) whose movement was blocked first is driven. The amount of pressurized fluid supplied to the cylinder (6a or 6b) and the amount of pressurized fluid discharged from the cylinder (6a or 6b) decrease, and the other finger (3b or 3
A gripper for a robot, characterized in that the gripper is configured to increase the amount of pressurized fluid discharged from the cylinder (6b or 6a) that drives the gripper. 2 The spool 20 has piston portions 23a, 23b provided at both ends, and piston portions 23a, 23b provided at both ends.
Two large diameter parts 2 arranged at equal intervals between 23b
5a, 25b, and three small diameter portions 24a, 24b, 24c formed between the large diameter portions 25a, 25b and the piston portions 23a, 23b, and each of the supply channels 12a, 12b,
The two outer small diameter portions 24a, 24b of the small diameter portions 24a, 24b, 24c are connected to each other through the periphery thereof, and each of the discharge passages 16a, 16b is an annular groove formed in the large diameter portions 25a, 25b. 2. A gripper for a robot according to claim 1, wherein the grippers are connected to each other through the grippers. 3 The regulating valve 18 is provided with another discharge passage 22, and the discharge passage 22 is connected to the small diameter portion 2.
4a, 24b, 24c, the central small diameter part 24c
The gripper for a robot according to claim 2, wherein the gripper is connected around the periphery of the gripper. 4 When the spool 20 is removed from the center position, the pressurized fluid flows into the grip side chamber (13a or 13b) of the cylinder (6a or 6b) on the finger (3a or 3b) side that contacted the workpiece 9 first. The gripper for a robot according to any one of claims 1 to 3, wherein the gripper is configured to be supplied to the chamber (15a or 15b) on the remote side.