JPH07119712A - Air cylinder - Google Patents

Abstract

PURPOSE:To enable an air cylinder used in plant facilities, etc., to be stopped regardless of action speed and the position of its rod. CONSTITUTION:An air cylinder 11 has a rod 12 and a nut part 13, and outer circumference of the nut part 13 is formed into a rotor 14 so as to constitute a stepping mortar 16. When air pressure is supplied to the air cylinder 11 while the stepping motor 16 is not energized, the nut part 13 is in its self lock state so as not to move and therefore the rod 12 does not move. When the stepping motor 16 is energized and rotation torque is applied on the nut part 13, the nut part 13 is rotated so as to move the rod 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air cylinder for carrying objects.

[0002]

2. Description of the Related Art Conventionally, air cylinders have been used in factory equipment. The stop position of the rod of this air cylinder was either the position where the stroke was full or the position where the rod could not move anymore due to contact. Further, in order to stop the rod at an intermediate position, the movement position of the rod is detected by a limit switch or the like and the air supply is stopped by an electromagnetic valve or the like.

FIG. 5 shows a control block diagram of a conventional air cylinder. First, when operating the rod 2 in the direction of moving out of the air cylinder 1, the sequencer 3 sets the valve 4 of the air cylinder 1 to pneumatic exhaust and the valve 5 to pneumatic supply. The rod 2 operates up to the full stroke of the air cylinder 1 and stops, or stops at a position regulated by contact. On the contrary, when the sequencer 3 sets the valve 4 of the air cylinder 1 to pneumatic supply and the valve 5 to pneumatic exhaust, the rod 2 moves in the direction of retracting into the air cylinder 1 and stops at the fully retracted position.
Further, when the rod 2 is stopped during the stroke, the position of the rod 2 is detected by the limit switch 6, and the valves 4 and 5 are closed according to an instruction from the sequencer 3 to stop the rod 2.

[0004]

However, in the above-mentioned conventional structure, the limit switch 6 detects the position of the rod 2 and opens and closes the valves 4 and 5 to supply and exhaust the air, which is an elastic body, to remove the rod 2. Since it is stopped midway, an overrun occurs from the opening / closing operation of the valves 4 and 5 to the stop, making it difficult to control with high accuracy.

[0005]

In order to solve the above-mentioned problems, the present invention solves the above problems by providing a piston that reciprocates in a cylinder, a rod having a screw structure provided parallel to the moving direction of the piston, and a rod of the rod. A nut that meshes with the screw and a rotating unit that rotates the nut are provided.

[0006]

With the above-described structure, the present invention can control the movement of the rod by rotating the nut.

[0007]

【Example】

(Embodiment 1) FIG. 1 is a configuration diagram of an air cylinder in a first embodiment of the present invention.

The rod 12 provided on the piston 50 of the air cylinder 11 has a screw structure. Nut part 13
Is supported inside the air cylinder 11 via a bearing 19 and meshes with the rod 12 to rotate. A rotor 14 is provided on the outer periphery of the nut portion 13, a stator 15 is provided inside the air cylinder 11 so as to face the rotor 14, and a stepping motor 16 is configured. The rotation and stop of the stepping motor 16 causes the nut portion 13 to rotate and stop, whereby the rod 12 moves and stops in the axial direction. Further, a screw lead is selected such that even if a thrust is applied to the rod 12 and the nut portion 13, the nut portion 13 does not rotate in a self-locking state when the stepping motor 16 is not energized.
Further, in order to maintain the air pressure that generates the thrust of the air cylinder 11, a seal 17 is provided at the contact portion between the nut portion 13 and the air cylinder 11. Also, the nut part 1
A mesh seal 1 is provided at a meshing portion between the rod 3 and the rod 12.
8 is provided to prevent air leakage.

FIG. 2 is a relationship diagram between the rotational torque and the friction coefficient of the nut portion 13 of the air cylinder in the first embodiment of the present invention. The vertical axis represents the rotation torque of the nut portion 13, and the horizontal axis represents the friction coefficient between the nut portion 13 and the rod 12.
When the set friction coefficient μ between the nut portion 13 and the rod 12 is larger than the critical friction coefficient μ0 determined by the lead pitch and the screw diameter, the nut portion 13 and the rod 12 are in a self-locking state, and the nut portion 13 receives a rotational force from the outside. Unless applied, the nut portion 13 does not rotate and the rod 12 does not move even if an axial force is applied to the rod 12. In this state, in order to apply the rotation torque to the nut portion 13 to rotate the nut portion 13, it is sufficient to apply a torque greater than the self-lock releasing torque shown by the solid line to the nut portion 13. Further, when the rotational torque is removed, the nut portion 13 and the rod 12 are in the self-locking state again. The nut portion 13 and the rod 12 of FIG. 1 are arranged so that the nut portion 13 and the rod 12 are in the self-locking region shown in FIG.
Since the friction coefficient between the rod 12 and the rod 12 is set, the rod 12 can be moved only when the nut portion 13 is rotated by the stepping motor 16 even when a thrust force is applied to the rod 12 by the supply of air pressure.

The air cylinder 11 constructed as described above
The operation will be described with reference to FIG. First, the valve 21
When the valve 20 is set to the air pressure supply state and the valve 20 is set to the air pressure exhaustion state, the rod 12 exerts a thrust force in the direction to exit from the air cylinder 11. At this time, if the stepping motor 16 is not energized, the nut portion 13 does not rotate in the self-locking state and the rod 12 does not move. In this state, when the stepping motor 16 is energized and the nut portion 13 is rotated so that the rod 12 moves in the same direction as the thrust by the air pressure, the rod 12 moves. Further, when the power supply to the stepping motor 16 is stopped, the nut portion 13 becomes the self-locking state again and does not rotate, so that the rod 12 is not rotated.
Will stop. Next, when the rod 12 is moved in the direction of retracting into the air cylinder 11, first, the valve 20 is set to supply air pressure and the valve 21 is set to discharge air pressure.
In this state, when electricity is applied to the nutping portion 13 so that the nut portion 13 rotates in the direction in which the rod 12 is retracted to the stepping motor 16, the rod 12 moves. Also, when the power supply is stopped,
The rod 12 also stops.

As described above, by rotating and stopping the nut portion 13 by the stepping motor 16, the rod 12
Moves and stops. Further, the operating speed of the rod 12 can be changed by changing the rotation speed of the stepping motor 16. The axial thrust of the rod 12 is generated by air pressure, and the stepping motor 16
Since only the rotational torque until the nut portion 13 comes out of the self-locking state starts to rotate, the stepping motor 16 can control a high thrust with a small control power.

Next, FIG. 3 is a control block diagram of the air cylinder in the first embodiment of the present invention. Sequencer 2
3 sends a signal to the valves 20 and 21 of the air cylinder 11 to control the opening and closing of the valves 20 and 21. The controller 22 can set a plurality of rotation angles of the stepping motor 16, and one of the rotation angles set by an external signal or a switch is selected.

First, a signal indicating that the rod 12 is coming out of the air cylinder 11 is sent from the sequencer 23 to the valves 20, 21.
The same signal is sent to the controller 22 at the same time as it is sent to. Upon receiving this signal, the controller 22 rotates the stepping motor 16 via the driver 24 in the direction in which the rod 12 exits to a preselected rotation angle and then stops it. As a result, the rod 1 will reach the preselected position.
Stop after 2 moves. With this configuration, the rod 12 can be stopped at a predetermined position by a signal from the sequencer 23. When the stop position of the rod 12 is changed by changing the production model, it can be dealt with only by changing the selection value of the controller 22.

(Embodiment 2) FIG. 4 is a configuration diagram of an air cylinder according to a second embodiment of the present invention. As shown in FIG. 4, the motor 31 for rotating the nut portion 13 is the rod 12
And a nut 13 using a transmission mechanism such as a belt 32 on another shaft.
It is also possible to adopt a structure for rotating. Further, as the type of the motor 31, a servo motor can be used instead of the stepping motor.

The operating principle of these embodiments is the same as that of the first embodiment and has the same features.

[0016]

As described above, according to the present invention, the piston reciprocating in the cylinder, the rod having the screw structure provided in parallel with the moving direction of the piston, the nut meshing with the screw of the rod, and the nut. With the rotation means for rotating, it is possible to control the movement of the rod by the rotation of the nut, and the movement speed of the rod of the cylinder having a large thrust due to the air pressure and the stop at an arbitrary position,
A motor driven by a small electric signal enables precise control, facilitating design in production equipment, downsizing equipment by improving functions, and easily changing stop position settings accompanying model changes. it can.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an air cylinder according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the rotational torque and the friction coefficient of the nut portion of the air cylinder in the first embodiment of the present invention.

FIG. 3 is a control block diagram of the air cylinder according to the first embodiment of the present invention.

FIG. 4 is a configuration diagram of an air cylinder according to a second embodiment of the present invention.

FIG. 5 is a control block diagram of a conventional air cylinder.

[Explanation of symbols]

 11 Air Cylinder 12 Rod 13 Nut Part 14 Rotor 15 Stator 16 Stepping Motor 17 Seal 18 Engagement Seal 19 Bearing 20 Valve 21 Valve 50 Piston

Claims (3)

[Claims] 1. A cylinder, a piston reciprocating in the cylinder, a supply means for supplying air pressure to the piston, a rod having a screw structure provided in parallel with the moving direction of the piston, and a rod of the rod. An air cylinder comprising: a nut that meshes with a screw; and a rotating unit that rotates the nut. 2. The air cylinder according to claim 1, wherein the rotating means is composed of a rotor provided on a nut and a stator provided on the outer circumference of the rotor. 3. The air cylinder according to claim 1, wherein the rotating means rotates the nut via a transmission mechanism.