JPH0341317B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (1) Field of Industrial Application This invention relates to a gripping device for a robot that positions and grips a workpiece, and in which fingers actively move after gripping the workpiece.

(2) Conventional technology Today, industrial robots are used for welding, assembly,
It is widely used and active in transfer work, press work, etc. This industrial robot has a motor attached to the drive part, and this motor operates according to the command from the control device, and the amount of movement is controlled via an encoder connected to the motor's rotating shaft. Feedback is sent to the device so that it can repeatedly operate as instructed.

(3) Problems to be solved by the invention In such a robot, when a workpiece is inserted into a hole and an assembly operation is performed, machining debris (commonly called "burrs") may adhere to the workpiece or the hole. If the hole is closed, the workpiece must be inserted into the hole with strong force. Therefore, a force in the opposite direction that tries to prevent the robot's drive unit from performing a predetermined movement is applied, making it unable to move as instructed by the control device, resulting in a servo error and causing the robot to come to an emergency stop. I end up.

"Burrs" that cause servo errors like this
This is hardly a problem in human assembly work, but removing burrs on a robot to prevent servo errors requires a great deal of effort and high precision.

In view of the above-mentioned disadvantages of conventional robots, the present invention has been developed to prevent the robot from causing a servo error even when the robot is required to perform work that requires a force exceeding a predetermined value on the finger. The purpose of this invention is to propose a gripping device for a robot that allows work to continue smoothly.

[Structure of the Invention] (1) Means for Solving the Problems The present invention, as a means for solving the above problems, provides two pistons with different maximum strokes back to back, and a piston rod connected to each piston. A cylinder device that protrudes in opposite directions to each other, a finger that is attached to each of the piston rods that protrudes from the cylinder device and faces each other, and that grips a workpiece with the opposing portions, and a pair of pistons that are driven by compressed fluid. synchronously urge each other in opposite directions and move to the base end of the stroke,
A first supply/exhaust means for positioning the pair of fingers at the non-gripping end of the workpiece; and a first supply/exhaust means for synchronously urging the pair of pistons with compressed fluid in a direction opposite to the direction of movement by the first supply/exhaust means to reach the end of the stroke. At the same time, the pressure of the compressed fluid supplied to the piston was made relatively higher for the piston whose maximum stroke was relatively small, and the piston whose maximum stroke was relatively small was positioned at the end of the stroke. a second supply/exhaust means for causing the fingers to grip the workpiece in a state where the fingers grip the workpiece; and in a state in which the fingers grip the workpiece, air supply to the piston having a relatively small stroke is cut off, and the other piston is energized by compressed fluid. With a pair of fingers,
A third supply/exhaust means for parallelly moving the work gripped by the fingers is adopted to achieve the intended purpose.

(2) Operation When gripping a workpiece with the gripping device attached to the robot arm, first, the first supply/exhaust means positions the pair of fingers at the non-grip end of the workpiece, and then the second supply/exhaust means moves both pistons. are moved synchronously in opposite directions from the base end of the stroke to grasp the workpiece with the fingers. At this time, the compressed fluid pressure supplied to the piston is higher for the piston with a relatively small maximum stroke, so the pair of fingers is placed on the workpiece while the piston with a relatively small stroke is positioned at the end of the stroke. is gripped, and the piston with the relatively larger maximum stroke is restrained at a position just before the end of the stroke. After gripping a workpiece with the fingers, when the robot arm is started and the workpiece is moved to a predetermined position to fit the workpiece into a hole, etc., the third supply/exhaust means is used to select the one with the relatively smaller maximum stroke. When the supply of compressed fluid to the piston is cut off, the force of the other piston, which is still being supplied with compressed fluid, overcomes the force and the piston moves further toward the end of its stroke.Following this, the workpiece moves toward the robot arm. The workpiece is moved in parallel independently of the operation of the robot arm, and the workpiece can be inserted into a so-called burred hole without applying an overload to the robot arm that would cause a servo error.

(3) Examples Examples of the present invention will be described below with reference to the drawings.

The gripping device of the embodiment shown in FIG. 1 is for gripping the frame of a micrometer, and has a cylinder device C equipped with two pistons back to back, which will be described later. This cylinder device C includes two cylinders 18 and 22 whose axes coincide with each other, and the opposing open ends of both cylinders are closed by a partition 1 provided in the center. This partition 1
In FIG. 1, both sides have columnar connecting portions 2 and 3 at the upper and lower portions, and each connecting portion 2 and 3 is provided with air inlet and outlet holes 4 and 5 that open at the outer peripheral surface.

Further, cylinders 18 and 2 facing the partition 1
Both sides of 2 are closed with rod guides 6 and 7. These rod guides 6 and 7 have cylinder 1 inside.
8 and 22, and air inlet and outlet holes 10 and 11 are provided on the outer circumferential side of each of the coupling parts 8 and 9, respectively, and communicate with the insides of the cylinders 18 and 22.

Furthermore, pistons 12 and 13 attached to cylinders 18 and 22 are provided at the axial center of the rod guides 6 and 7.
Piston rods 14 and 15 integrally connected to the piston rods are slidably inserted and supported. Note that the piston 12 is formed to have a longer axial length than the piston 13, and the piston 13 is configured to have a larger stroke than the piston 12. Additionally, O-rings 16,
17 is provided to prevent outside air from entering the inside of the cylinder.

With the configuration as described above, the cylinders 18, 22
Inside, cylinder chambers C1 and C2 are formed at the front faces of the pistons 12 and 13. Note that there is a gasket 1 between the joints 2 and 8 and the cylinder 18.
9 and 20 are provided, and a piston ring 21 is provided on the outer peripheral surface of the piston 12 to seal the sliding surface with the inner peripheral surface of the cylinder 18.

Similarly, gaskets 23 and 24 are provided between the coupling parts 3 and 9 of the opposite example of the partition 1 and the cylinder 22, and a piston ring 25 is similarly provided for the piston 13.
is provided.

In this way, the partition 1 and the rod guides 6, 7 that constitute the cylinder chambers C1, C2 are screwed into the screws 28, 29.
It is fixed to the rods 26 and 27 by means such as the above, and maintains a predetermined positional relationship.

Furthermore, fingers 30 and 31 that slide on the guide rod 27 are fixed to the tips of the piston rods 14 and 15 with bolts 32 and 33. In addition, the guide rod 27 and fingers 30, 3
Drive shafts 34 and 35 are interposed between the fins 30 and 1 to smooth the movement of the fins 30 and 31. Moreover, claws 37 and 38 for securely holding a workpiece (for example, a frame) 36 are provided on the free ends of the fingers 30 and 31 to protrude back to back.

Next, the air circuit of this gripping device will be explained based on FIG. 2.

A pressure regulator 40 is connected to the air pressure source 39 . This pressure regulator 40 includes a filter regulator 41, a pressure gauge 42, and a mist separator 4.
It is composed of 3. This pressure regulator 40
A pressure switch 44 and a regulator 45 are connected to. This regulator 45 is equipped with another pressure gauge 46, and a solenoid valve 47 and a regulator 48 are connected.

The solenoid valve 47 is connected to the air inlet/outlet hole 4 of the cylinder device C.
However, when the air inlet/outlet hole 4 and the air pressure source 39 are communicated, air is supplied into the cylinder chamber C2, and when the solenoid valve 47 is operated, the air supply is cut off and the air in the cylinder chamber C2 is discharged. I'm starting to do that.

A solenoid valve 50 is connected to the regulator 48 via a pressure gauge 49 to the air inlet/outlet holes 10, 11 of the cylinder device C, and is also connected to the air inlet/outlet hole 5 via a speed controller 51. Air is supplied to the air inlet/outlet hole 5 through the air inlet/outlet hole 51, and when the solenoid valve 50 is operated, the air inlet/outlet hole 10,
Air is supplied to 11 and exhausted from air inlet and outlet holes 5.

Note that the pressure of air supplied to the cylinder chamber C2 via the solenoid valve 47 is set higher than the pressure of air supplied to the cylinder chamber C3 via the speed controller 51.

Next, the operation of this embodiment will be explained.

In FIG. 1, when the fingers 30 and 31 that grip a workpiece 36 are narrowing the distance between the fingers in preparation for gripping, the solenoid valves 47 and 50 are operated simultaneously. At this time, the solenoid valve 47 opens the exhaust circuit of the cylinder chamber C2, and the solenoid valve 50 opens the pressure regulator 40, the regulator 45, and the regulator 4 on the one hand.
8 opens the pressurized air supply circuit constituted by 8, and on the other hand opens the exhaust circuit of the cylinder chamber C3.
9 air operates pistons 12 and 13,
The pistons 12, 13 move towards each other and, via the piston rods 14, 15, draw together the fingers 30, 31 in the direction of the partition 1 provided in the central part of the cylinder device C. Therefore, the distance between the claws 37 and 38 at the tip of the finger is shortened. During this time, the air in the cylinder chamber C2 is exhausted through the solenoid valve 47, and the air in the cylinder chamber C3 is exhausted through the speed controller 51 and the solenoid valve. In this state, the pistons 12 and 13 are in contact with the end faces of the coupling parts 2 and 3 and are positioned at the base ends of their strokes, and the fingers 37 and 38 are in a position to grip the workpiece.

Next, when gripping this workpiece, the solenoid valves 47 and 50 are turned off to return to the state shown in FIG. 2. By this operation, on the one hand, air is supplied to the cylinder chamber C2 via the solenoid valve 47, causing the piston 12 to move downward in FIG. Air is supplied and the air in the syringe chambers C1 and C4 is exhausted via the solenoid valve 50, so the piston 13 rises in the figure.
The fingers 30, 31 hold the workpiece 36 from inside as shown in FIG. In this case, the air supplied to the cylinder chamber C2 passes through the regulator 48 and the speed controller 51.
3, and the maximum stroke of the piston 12 is relatively smaller, so the piston 12 moves faster and contacts the end face of the joint 8 first, reaching the end of the stroke. , and the piston 12 is positioned at that position because it is pressed by relatively high-pressure air. When the workpiece 36 is gripped by the pair of fingers 30, 31, the air pressure against the piston 12 is strong, so the piston 13 on the opposite side is restrained at a position just before the end of its stroke, and the gripping position of the workpiece is fixed.

While gripping the workpiece 36 in this way,
Next, when the solenoid valve 47 is activated,
The air in the cylinder chamber C2 is supplied to the solenoid valve 47.
Since the exhaust is exhausted through the cylinder chambers C1 and C2
Since the air pressure is gone and the finger 30 is in a free state, it continues to be in the cylinder chamber C.
Piston 1 due to the pressure of air supplied to 3
3 rises slowly. Therefore, the finger 31 rises at a slow speed, and the workpiece 36 rises along with the claw 38, that is, the finger 31. Therefore, the finger 30 in a free state is also pushed up along with the piston 12 via the workpiece 36, and the workpiece 36 moves upward slowly while being held by the fingers 30, 31. Therefore, if there is an object to be inserted above, the work 36 becomes the object to be inserted and the object is pushed in, and if the work 36 is an insert, it is pushed into the object to be inserted above, and this operation is performed by a robot. Does not require arm drive.

When releasing the workpiece 36, the solenoid valve 50 is operated again, the pistons 12 and 13 are moved relatively closer to each other, and the claws 3 of the fingers 30 and 31 are moved closer to each other.
7 and 38 are separated from the workpiece 36.

As explained above, according to this embodiment, the fingers 30 and 31 can be synchronously moved upward after gripping the workpiece 36, so that the robot can move the workpiece to the inserted object. In the work of pushing the workpiece into the workpiece, the robot arm is operated to move the workpiece to the push-in position, and after positioning, the workpiece can be pushed in using the fingers 30, 31 of this gripping device. Therefore, when there is a "burr" on the workpiece 36 or the like and it becomes necessary to push it in with unnecessary strong force, the robot arm is already positioned and the drive section is in a braked state. Even if the workpiece 36 is moved by the gripping device, the workpiece 36 can be pushed in while being separated from the movement of the robot arm, and the robot arm drive section will not suffer from a servo error. For this reason,
Even if there is a slight burr on the workpiece 36, the robot can continue its work smoothly without sensing a servo error, indirectly giving flexibility to the robot arm that moves uniformly. The robot's working ability can be further improved.

It should be noted that the present invention is not limited to the above-mentioned embodiment, but may be one in which two independent cylinders are arranged back to back. Moreover, the piston 12,
Although the axial lengths, that is, the thicknesses of the pistons 12 and 13 were changed in order to have a stroke difference between the pistons 13, the lengths of the cylinders 18 and 22 with the same piston thickness may be changed. Furthermore, in the embodiment, claws 37 and 38 are provided on the outside of the fingers 30 and 31,
When the fingers 30 and 31 open, the workpiece 36
However, claws may be provided inside the fingers 30, 31 to grip the workpiece 36 when the fingers 30, 31 are closed. In this case, the two cylinders 18 and 22 may be formed independently and installed so that the piston rods 14 and 15 are oriented relative to each other.
Further, in the above embodiments, the actuator is operated by pneumatic pressure, but it may be actuated by hydraulic pressure, and various other modifications are possible without changing the gist of the present invention.

[Effects of the Invention] According to the present invention, a maximum stroke difference is set for a pair of pistons, and when gripping a workpiece, the compressed fluid pressure supplied to the pistons with relatively small maximum strokes is increased. Therefore, the gripping position of the workpiece with respect to the gripping device is initially always kept constant by the stroke end position of the piston whose maximum stroke is relatively small, and the workpiece can be easily positioned and gripped with respect to the gripping device. can. In this state, the piston with a relatively large maximum stroke is restrained before reaching the end of its stroke, and even if a situation arises in which the robot must perform work that requires a force greater than a predetermined value, By cutting off the supply of compressed fluid to the piston with the smaller stroke, the piston on the opposite side can further move the workpiece in parallel, making it possible to move the workpiece independently while the robot arm is stopped. This has the effect of preventing the robot from causing a servo error due to overload of the robot arm, allowing the robot to carry out work smoothly and safely.

[Brief explanation of drawings]

The drawing shows one embodiment of the present invention.
The figure is a sectional view showing the structure of the gripping device, and FIG. 2 is an air circuit diagram of the drive device. C... Cylinder device, 1... Partition cover, 4,
5... Air inlet/outlet hole, 6, 7... Rod guide,
10, 11... Air inlet/outlet hole, 12, 13... Piston, 14, 15... Piston rod, 17,
22...Cylinder, 30, 31...Finger, 3
7, 38...nail, 39...air pressure source, 40...pressure regulator, 45...regulator, 47...solenoid valve, 48...regulator, 50...
Solenoid valve.

Claims (1)

[Scope of Claims] 1. A cylinder device including two pistons with different maximum strokes placed back to back, and in which piston rods connected to each piston protrude in opposite directions, and each of the piston rods protruding from the cylinder device. fingers that are attached and face each other and for gripping a workpiece at opposing portions; and a pair of pistons that are synchronously urged in opposite directions with compressed fluid to move to the base end of the stroke; a first supply/exhaust means for positioning the finger at the non-gripping end of the workpiece; synchronously urging the pair of pistons with compressed fluid in a direction opposite to the direction of movement by the first supply/exhaust means;
At the same time as moving the piston toward the end of its stroke, the pressure of the compressed fluid supplied to the piston is relatively higher for the piston whose maximum stroke is relatively small, so that the piston whose maximum stroke is relatively small is moved toward the end of its stroke. a second supply/exhaust means for causing the fingers to grip the work in a positioned state; and in a state in which the fingers grip the work, air supply to the piston having a relatively small stroke is cut off, and the other piston is supplied with compressed fluid; A gripping device for a robot, comprising: a pair of fingers; and a third supply/exhaust means for parallelly moving a workpiece gripped by the fingers in conjunction with the movement of the workpiece toward the end of the stroke.