JPH0775990A - Collision protective device - Google Patents

Abstract

PURPOSE:To shorten response time from the interference time to the pressure release of a pressure chamber by constituting in such a way as to release the pressure of the pressure chamber by mechanical action associated with the receding motion of a free piston at the interference time, not through a detecting sensor or a solenoid changeover valve. CONSTITUTION:A free piston 3 is mounted in the freely reciprocated state in a cylinder 1, and a supporting rod 14 is engagedly fixed into the opening end part of the cylinder 1 through a ball joint unit 10. The free piston 3 and the ball joint unit 10 are provided with a pair of engaging part 17, 18 with the inclined faces brought into contact with them so as to be fitted in uneven form. Air pressure is supplied from an air supply port 6 into a pressure chamber 4 partitioned by the bottom part of the cylinder 1 and the free piston 3. A cylinder wall facing the pressure chamber 4 is provided with exhaust ports 21a, 21b, and these exhaust ports 21 are opened by a valve member 23 moving along with the free piston 3 when the free piston 3 is put in receding motion in the cylinder 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a collision protection device equipped on a robot or the like.

[0002]

2. Description of the Related Art Usually, a robot protects the robot itself and a jig holding part (hereinafter, referred to as a robot) from an impact when a jig or tool held by the robot hits a work or an obstacle. Equipped with collision protection device. As a conventional collision protection device, for example, one shown in FIG. 3 is known (Japanese Utility Model Laid-Open No. 63-140393). This collision protection device
It is mounted between the robot 80 and a jig / tool 81 provided to the robot 80. A cylinder 82 having a bottomed cylindrical shape is fixed to the robot 80 side, and a jig / tool is attached to the tip of a support rod 83 held by the cylinder 82. 81 is attached. More specifically, a free piston 84 is reciprocally mounted in the cylinder 82, and a support rod 83 is attached to an opening end of the cylinder 82 via a ball joint unit 85. The free piston 84 and the ball portion 86 of the ball joint unit 85 have a pair of V-grooves 8 as a pair of engaging portions in which inclined surfaces are brought into contact with each other so that concave portions and convex portions are fitted.
7 and a key member 88 are provided respectively.

An air supply / exhaust port 90 is provided on the cylinder wall, which faces the pressure chamber 89 defined by the bottom of the cylinder 82 and the free piston 84, and air is introduced into the pressure chamber 89 by switching the electromagnetic switching valve 91. Air supply and exhaust are possible. An interference detection sensor 92 is attached to one side of the cylinder 82. The tip of the interference detection sensor 92 is inserted into a hole 82a opened in the cylinder 82, and the detector 92a is engaged with the recess 84a of the free piston 84. The interference detection sensor 92 includes a detector 92
By moving a from the concave portion 84a and riding on the peripheral surface of the free piston 84, the backward movement of the free piston 84 is detected, and this signal is sent to the electromagnetic switching valve 91 via the relay circuit.

In this collision protection device, during normal operation, the free piston 84 is supplied by supplying air pressure into the pressure chamber 89.
Moves forward and the key member 88 and the V groove 87 are engaged,
Accordingly, the support rod 83 is fixedly held by the cylinder 82 via the ball joint unit 85. At this time, the detector 92a of the interference detection sensor 92 is engaged with the recess 84a of the free piston 84. When the jig 81 attached to the support rod 83 interferes with or collides with the work or the obstacle, the ball portion 86 of the ball joint unit 85 rotates and the free piston 84 retracts. The backward movement of the free piston 84 is detected by the interference detection sensor 92, and the signal from the sensor 92 switches the electromagnetic switching valve 91 to the exhaust side. As a result, the air in the pressure chamber 89 is discharged to the outside from the air supply / exhaust port 90, the free movement of the free piston 84 is allowed, and the impact of interference and collision is mitigated.

[0005]

As described above, in the above-mentioned conventional collision protection device, when the pressure in the pressure chamber 89 is released at the time of interference, the signal detected by the interference detection sensor 92 is transferred to the electromagnetic switching valve 91 via the relay circuit. And the electromagnetic valve operation according to this. Therefore, it takes about 100 ms from the interference operation until the pressure in the pressure chamber 89 is released, which causes a problem of poor responsiveness. More specifically, in the above-mentioned relay circuit, it takes 25 ms from the relay ON in the controller to outputting the valve excitation signal, and in the solenoid valve operation, it takes 45 ms to move the valve spool by receiving the valve excitation signal. It takes several tens of milliseconds until the air in the pressure chamber 89 is actually exhausted and the pressure is released. As a result, the pressure chamber 89 is compressed for about 100 ms from the time of interference, and the reaction force exerts a load on the robot 80. And
If the frequency of interference is high, the robot 80 will be damaged and the position accuracy and trajectory accuracy will be reduced.

The present invention has been made in view of the above circumstances, and enables the pressure in the pressure chamber to be released by a mechanical operation associated with the retreat of the free piston without using a detection sensor or an electromagnetic switching valve. Therefore, shortening the response time from the time of interference to the pressure release of the pressure chamber is a technical problem to be solved.

[0007]

SUMMARY OF THE INVENTION A collision protection device of the present invention for solving the above problems is a cylinder having a bottomed cylinder, a free piston reciprocally mounted in the cylinder, and an opening end portion of the cylinder. A support rod engaged through a ball joint unit whose removal is restricted to a pair, and a pair of engagements which are provided in the free piston and the ball joint, respectively, in which inclined surfaces are brought into contact with each other to make concave and convex fits. A pressure chamber defined by a bottom portion of the cylinder and the free piston, and an air supply port provided on a cylinder wall facing the pressure chamber, wherein the pressure is applied to the cylinder. An exhaust valve mechanism provided with an exhaust port provided on a cylinder wall facing the chamber and a valve member for opening and closing the exhaust port is attached, and the free piston reduces the volume of the pressure chamber. When moving in the direction that is characterized in that with the free piston valve member is configured to open the exhaust port by moving.

[0008]

In the collision protection device of the present invention, for example, the cylinder is held by a robot or the like, and a jig or the like is attached to the tip side of the support rod for use. In normal use, by supplying air pressure from the air supply port into the pressure chamber,
The free piston advances in the cylinder, and a pair of engaging portions provided on the free piston and the ball portion are engaged with each other. As a result, the support rod is held in a fixed state through the ball joint unit, which is restricted from falling out in the cylinder opening end.

When a jig or the like mounted on the support rod interferes with or collides with a work or an obstacle, the ball portion of the ball joint unit rotates, and a pair of engaging members respectively provided on the free piston and the ball joint. The free piston moves backward due to the sliding of the inclined surface at the joint. In the collision interference device of the present invention, since the valve member of the exhaust valve mechanism moves together with the retracting free piston, when the free piston retracts due to interference, the exhaust port is immediately opened. As a result, the air in the pressure chamber is immediately evacuated, and the free piston is allowed to move freely.As a result, the support rod with jigs and tools can move smoothly in any direction, and the impact of collision Is alleviated.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 and 2, reference numeral 1 denotes a cylinder having a bottomed cylindrical shape, the rear end of which is a wrist plate 2 of the robot 2.
It is held by the robot 2 in such a manner that it is connected to a and the opening side faces downward. A free piston 3 is slidably installed in the cylinder 1. The free piston 3
A pressure chamber 4 having a circular cross section is defined between the cylinder and the bottom of the cylinder. The pressure chamber 4 includes a cylinder 1 and a free piston 3.
The airtightness is maintained by the seal member 5 interposed between and. Further, air pressure is introduced into the pressure chamber 4 from a pipe 20 connected to an air source (not shown) via an air supply port 6 provided on the side wall of the cylinder 1.

The free piston 3 is formed in a cylindrical shape with a bottom, and an elongated hole 7 extending in the axial direction of the cylinder 1 is provided in a part of a side wall extending downward. A tip portion of a pin 8 mounted on the cylinder 1 is slidably fitted into the elongated hole 7, and thereby the free piston 3 is restricted from rotating around the axis of the cylinder 1. .

On the other hand, in the opening end of the cylinder 1, a ball joint unit 10 is attached by using a lid 9 bolted to the opening end of the cylinder. The ball joint unit 10 is composed of a spherical ball portion 11 and a receiving portion 12 for holding the ball portion 11 on a spherical surface 12a. The receiving portion 12 is seated on the lid body 9. ing. The lid 9 has an annular projection 9a at a position surrounding the receiving portion 12.
The receiving portion 12 is slidable along the annular projection 9a. Further, in the engaged state of the ball joint unit 10, a predetermined gap 13 is formed between the outer surface of the receiving portion 12 and the inner surface of the cylinder 1, and a part of the free piston 3 extends in this gap 13. is doing.

Reference numeral 14 is the ball joint unit 1 described above.
A support rod extending downwardly from the ball portion 11 of 0 through the central hole 9b of the lid body 9, and a chuck unit 15 for holding a jig is fixed to the lower end of the support rod 14. A holding plate 16 is integrally provided. In addition, the ball portion 11 of the ball joint unit 10
A V-groove 17 is provided on the side opposite to the support rod, while a key member 18 engaging with the V-groove 17 is attached to the free piston 3. The tip end of the key member 18 is V-cut in accordance with the angle of the V groove 17 (about 120 degrees as an example), so that when the key member 18 is fitted in the V groove 17, Rotation around the piston axis is restricted. A spring 19 for urging the free piston 3 forward is provided in the cylinder 1, but the spring force thereof is weak enough to restrict play of the ball joint unit 10 at the time of air discharge described later. It is a thing.

A first communication hole 2 is provided at the bottom of the cylinder 1.
1a and the 2nd communicating hole 21b through the pressure chamber 4 respectively.
And a valve accommodating chamber 22 having a circular cross section that communicates with the outside. The first communication hole 21a and the second communication hole 21b form the exhaust port 21 of the present invention. A valve member 23, which is seated on a conical seat surface 22a and closes the exhaust port 21 in an airtight manner, is slidably accommodated in the valve accommodating chamber 22. The inner surface of the valve housing chamber 22 and the outer surface of the valve member 23 are kept airtight by the seal member 24. In addition, a valve member 23 is provided in the valve accommodating chamber 22 (see FIG.
A spring 25 for urging the pressure chamber 4 is provided, but the spring force is such that it can withstand the pushing up from the pressure chamber 4. Further, a gap as small as possible is secured between the rod-shaped tip portion 23a of the valve member 23 and the free piston 3.

An interference detection sensor 27 is attached to one side of the cylinder 1 using a bracket 26.
This interference detection sensor 27 has a hole 1 opened in the cylinder 1.
The tip end is exposed inside a and the detector 27a is brought into contact with the free piston 3. On the peripheral surface of the free piston 3, there is provided a recess 3a that allows the detector 27a to be engaged at its forward end. Interference detection sensor 27
Has a function of detecting the retreat of the free piston 3 by moving the detector 25a out of the recess 3a and riding on the peripheral surface of the free piston 3, and this signal is for stopping the robot 2, for example. Can be used as a signal of.

With this configuration, when air pressure is supplied into the pressure chamber 4 in the cylinder 1, the free piston 3 advances and the key member 18 attached to the free piston 3 is inserted into the V groove 17 of the ball portion 11. After fitting, the ball portion 11 is fixed to the receiving portion 12 (state of FIG. 1). Therefore, under this condition, the robot work can be stably executed by the jig / tool provided to the chuck unit 15.

When a work or some interference interferes with the jig and tool of the chuck unit 15 from the lateral direction, the ball portion 11 of the ball joint unit 10 rotates in the receiving portion 12, and FIG. As shown, the key member 1
8 slides on the V groove 17, and the free piston 3 slightly retracts. When the free piston 3 retracts, the valve member 23 is also lifted by the free piston 3 against the spring 25, and the exhaust port 21 is opened. As a result, the air in the pressure chamber 4 is rapidly exhausted to the outside through the exhaust port 21, and the free piston 3 is allowed to move freely, so that the free tilting of the support rod 14 is ensured, thereby preventing the collision. The shock is reduced as much as possible. When the support rod 14 receives an interference right above, the entire ball joint unit 10 moves upward, the exhaust port 21 is opened and the pressure chamber 4 is exhausted in the same manner as described above. Similarly, the shock is alleviated.

As described above, in the collision protection device of this embodiment, the valve member 2 together with the free piston 3 that retreats at the time of interference.
Since 3 retreats and opens the exhaust port 21, the response time from the time of interference to the pressure release of the pressure chamber can be set to 1/3 or less of that in the case of using a conventional interference detection sensor or electromagnetic switching valve. did it. The shapes and positions of the exhaust port 21 and the valve member 23 as the exhaust valve mechanism attached to the cylinder 1 are not limited to those in the above-described embodiment, and various changes are made without departing from the scope of the present invention. It is possible, for example, the valve member 23 can be provided integrally with the free piston 3.

In the above embodiment, the ball portion 11
Although the V groove 17 and the key member 18 are provided on the free piston 3 respectively, the key member may be provided on the ball portion 11 and the V groove may be provided on the free piston 3 instead. The shape of these grooves and keys is not limited.

[0020]

As described above in detail, the collision protection device according to the present invention is designed so that the pressure of the pressure chamber can be released by the valve member that moves together with the free piston that recedes at the time of interference. Therefore, the response from the time of interference to the pressure release of the pressure chamber can be made extremely good as compared with the conventional device using the detection sensor and the electromagnetic switching valve.
Therefore, it is possible to prevent the damage of the robot or the like due to the deterioration of the responsiveness and the deterioration of the position accuracy and the trajectory accuracy. Further, since the electromagnetic switching valve is not required, the size and weight of the device can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a robot collision protection device according to an embodiment.

FIG. 2 is a cross-sectional view showing a state of the collision protection device at the time of interference.

FIG. 3 is a cross-sectional view of a conventional collision protection device.

[Explanation of symbols]

1 ... Cylinder 2 ... Robot 3 ...
Free piston 4 ... Pressure chamber 6 ... Air supply port 10 ... Ball joint unit 11
... Ball part 14 ... Support rod 17 ... V groove (engagement part) 18
... key members (engagement portions) 21a, 21b ... communication hole (exhaust port) 23
... Valve member

Claims (1)

[Claims] 1. A cylinder having a bottomed cylindrical shape, a free piston reciprocally mounted in the cylinder, and a support attached via a ball joint unit in which the opening end of the cylinder is restricted from coming off. A rod, and a pair of engaging portions that are respectively provided on the free piston and the ball joint and that are in concave and convex engagement by abutting mutually inclined surfaces.
A collision protection device comprising a pressure chamber defined by the bottom of the cylinder and the free piston, and an air supply port provided on a cylinder wall facing the pressure chamber, wherein the cylinder faces the pressure chamber. An exhaust valve mechanism provided with an exhaust port provided on a cylinder wall and a valve member for opening and closing the exhaust port is additionally provided, and when the free piston moves in a direction of reducing the volume of the pressure chamber, the free piston A collision protection device characterized in that the valve member moves together with a piston to open the exhaust port.