JPH07110005A - Positioning controlling method in servo cylinder - Google Patents

Abstract

PURPOSE:To quickly and accurately position a work in a target position by moving the work to a target position by means of compressed air and then positioning the work to the target position by means of a motor. CONSTITUTION:A servo cylinder device 10 is provided with a cylinder main body 16, which moves a work (W) by using an electropneumatic regulator 14 and compressed air, an electromagnetic switching valve 20, which supplies air to a cylinder 18 for braking and which blows off the compressed air from the cylinder 18, and a controller 20, which controls the positioning of the work (W). Inside the cylinder main body 16, a ball-screw shaft rotating mechanism is prepared, while a servo motor 64 is installed in parallel with the ball screw shaft, and an encoder 68 is provided to a driving shaft of the motor 64. The work (W), which is attached to a piston rod, is moved by the pressure of the air, which is supplied to a cylinder chamber. When the work (W) reaches a prescribed position in the vicinity of a target position, a motor 64 is driven for rotation, so that the work (W) is moved by means of bath rotary torque of the motor and the compressed air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servo cylinder positioning control method. More specifically, the piston rod of the cylinder is displaced by compressed air and a servomotor, and a work attached to the piston rod is moved to a target position. The present invention relates to a positioning control method in a servo cylinder that positions a head in a position.

[0002]

2. Description of the Related Art Conventionally, a work is attached to one end of a piston rod arranged in a cylinder, and compressed air is supplied to a cylinder chamber to displace the piston rod to move the work to a target position. The method of positioning is used.

This method of displacing the work by compressed air can drive a work with a large output and a large load, but since the air itself is a compressible fluid, it is substantially necessary to accurately position the work. Was difficult.

On the other hand, a method is used in which a work is attached to a ball screw, and the ball screw is rotated by a motor to displace the work and position it at a target position.

Since the method of displacing the work by this motor is an electric control, the stop position can be obtained exactly, but when a heavy work is transferred and positioned, a large motor is used. Must be used.

Therefore, there has been proposed a servo cylinder in which a work is transferred to the vicinity of a stop position by a cylinder using compressed air and a work is stopped from the vicinity of the stop position by a motor with high precision.

[0007]

However, the above-mentioned conventional techniques have not yet realized a method for positioning a workpiece at a target position with high accuracy using compressed air and a motor. Further, when transferring a heavy work, there is no choice but to select a motor having a large output, and as a result, there is a problem that the motor cannot be downsized sufficiently.

The present invention has been made in order to solve such a conventional problem, and in a servo cylinder in which a work attached to one end of a piston rod is displaced by compressed air and a motor, It is an object of the present invention to provide a positioning control method in a servo cylinder that can position a work at a target position with high accuracy and further reduce the size of a motor.

[0009]

To achieve the above object, the present invention provides a piston rod attached to a piston of a cylinder, a ball screw engaging with the piston rod, and a rotating ball screw. With a driving motor,
A positioning control method in a servo cylinder, wherein the piston rod is displaced by the pressure of air supplied to a cylinder chamber and the rotational force of the motor, and the work attached to the piston rod is positioned at a target position.
A first step of controlling the pressure in the cylinder chamber to displace the work to a predetermined position in the vicinity of a target position; and, when the work reaches the predetermined position, a motor is rotationally driven to rotate the motor and the rotation force of the motor. The second step of continuing the displacement of the work by the pressure of the air in the cylinder chamber, and the pressure of the air in the cylinder chamber when the predetermined time has elapsed since the servo motor started to rotate A third step of controlling the pressure to hold the load, and displacing the work by only the rotational force of the motor,
And a fourth step of positioning at the target position.

[0010]

In the servo cylinder positioning control method according to the present invention, when the work attached to the piston rod is displaced by the pressure of the air supplied to the cylinder chamber and the work reaches a predetermined position near the target position. , The motor is rotationally driven, and the work is displaced by the rotational torque of the motor and the compressed air.

Then, after a lapse of a predetermined time, the compressed air in the cylinder chamber is set to a pressure for holding the static load of the work, the work is displaced only by the rotational force of the motor, and the work is set at a preset position immediately before the target position. When it reaches, the brake mechanism for stopping the displacement of the work is urged to position the work at the target position.

Therefore, in the vicinity of the target position, the work is displaced by the motor control, so that the work can be positioned at the target position with high accuracy.

Further, when the work is displaced by the motor control, the compressed air in the cylinder chamber is set to a pressure for holding the static load of the work or a pressure equal to or higher than the pressure for holding the static load, so that a motor having a small torque is used. It becomes possible.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A positioning control method for a servo cylinder according to the present invention will be described in detail below with reference to the accompanying drawings, in connection with a device for carrying out the method for positioning control.

FIG. 1 is a block diagram showing the configuration of a servo cylinder device 10 embodying the present invention.

The servo cylinder device 10 includes an electropneumatic regulator 14 for adjusting the compressed air supplied from the compressed air supply source 12 to a predetermined pressure and outputting the compressed air, and an adjusted compressed air supplied from the electropneumatic regulator 14. The compressed air supplied from the compressed air supply source 12 is disposed between the cylinder body 16 for displacing the work W by the compressed air supply source 12 and the brake cylinder 18 disposed in the cylinder body 16. An electromagnetic switching valve 20 that supplies air to the brake cylinder 18 or discharges the compressed air of the brake cylinder 18 to the atmosphere, and a controller 22 that controls the positioning of the work W in the servo cylinder device 10.

The structure of the cylinder body 16 will be described with reference to the perspective explanatory view of FIG. 2 and the partial sectional explanatory view of FIG.

The cylinder body 16 has a head cover 24.
, A cylinder tube 26, a rod cover 28, and a table 30 that engages the work W.

Inside the cylinder body 16, as shown in FIG. 3, a compressed air supply mechanism 32 for supplying air into the cylinder tube 26 and a ball screw shaft rotating mechanism 34.
A disc brake mechanism 40 for braking the ball screw shaft 36 to stop the displacement of the piston 38, and the table 30.
A rotation stopping mechanism 42 is provided to prevent the rotation of the.

In the compressed air supply mechanism 32, the electropneumatic regulator 14 is disposed inside the head cover 24, and the electropneumatic regulator 14 includes the connection plate 44 and the passage 4.
The cylinder chamber 48 is communicated with the rod cover side cylinder chamber 50 via 6. A passage 54 communicating with the outside of the cylinder tube 26 is defined in the head cover side cylinder chamber 52 of the cylinder chamber 48.

In the ball screw shaft rotating mechanism 34, a ball screw shaft 36 is axially supported by an angular ball bearing 56 in the head cover 24 so as to be axially displaceable and rotatable. The ball screw shaft 36 is installed in the cylinder chamber 4
The thread groove 58 is engraved only in the portion corresponding to the inside of 8, and the pulley 60 is provided at one end thereof. The ball screw shaft 36 engages with a body 62 fitted inside the piston 38 via a ball.

Inside the head cover 24, a servo motor 64 is provided in parallel with the ball screw shaft 36, a pulley 70 is provided at the end of the drive shaft 66, and the rotation angle of the drive shaft 66 is adjusted. An encoder 68 for detecting is provided. Further, a timing belt 72 is suspended between the pulley 70 and the pulley 60 arranged on the ball screw shaft 36.

As shown in FIG. 4, the disc brake mechanism 40 is composed of a member arranged in the hole 74 of the head cover 24 in which the angular ball bearing 56 is provided. The hole portion 74 has a diameter reduced in two steps from the pulley 60 side of the ball screw shaft 36 toward the angular ball bearing 56, and for a brake having a L-shaped cross section in the radial direction on the bottom surface of the first step. A cylinder 18 is provided, and its bulging portion 18a is fixed so as to be directed toward the ball screw shaft 36 side. A cylindrical piston 76 having a substantially L-shaped cross section in the radial direction is arranged so as to come into contact with the inner peripheral surface of the brake cylinder 18.

The piston 76 includes a braking member 78 fixed to the pulley 60 side and a bulging portion 76a of the piston 76.
Is arranged so as to sandwich the bulging portion 18a of the brake cylinder 18, and the bulging portion 76a of the piston 76 or the braking member 78 comes into contact with the bulging portion 18a of the brake cylinder 18 so that the piston 76 The axial movable range of is regulated.

Further, a space 79 is defined between the piston 76 and the brake cylinder 18, and a piston packing 80a fitted to the outer peripheral surface of the piston 76 sliding on the inner peripheral surface of the brake cylinder 18 is formed. , 80b keep the space 79 airtight. The electromagnetic switching valve 20 communicating with the compressed air supply source 12 and the space 79 are communicated with each other via passages 81 and 82 defined inside the head cover 24 and the brake cylinder 18. A bearing pressing member 84 is fixed to the bottom surface of the second step of the hole 74, and a coil spring 86 is inserted between the bearing pressing member 84 and the piston 76.

Therefore, the piston 76 is constantly urged toward the pulley 60 by the coil spring 86. Further, the brake cylinder 18 is a braking member 90 that is a donut-shaped disc body via a support member 88.
I support you.

On the other hand, the ball screw shaft 36 is mounted with a brake disc 96 near the pulley 60 via a piece key 92 and a piece 94. The brake disc 96 is configured to rotate near the braking member 90.

The detent mechanism 42 is a piston rod 10
This mechanism prevents the table 30 displaced through 0 from rotating together with the piston rod 100.

The piston rod 100 has a cylindrical shape as shown in FIG.
It is screwed to the 8 side. A ball screw shaft 36 is provided in the hole 102 inside the piston rod 100.
It is inserted with the shaft center aligned without abutting on the wall surface of No. 2. The piston rod 100 is screwed to a shaft body 104, and the shaft body 104 is fixed to the table 30 with a bolt or the like not shown. Guide rods 106a and 106b are fixed to both ends of the table 30 by bolts (not shown). The guide rod 1
06a and 106b are axially slidably supported by ball bushes 108a and 108b provided on both side surfaces of the rod cover 28, and hole portions 112a and 112b of a flange 110 attached to the end surface of the rod cover 28.
Has been inserted into.

The head cover 24 has a terminal 1 for connecting a control signal and a power supply signal from the controller 22.
A terminal block 118 provided with 14, 116 is provided.

Cylinder body 16 constructed as described above
Is basically used with the head cover 24 as an upper part and standing upright.

Next, the configuration of the controller 22 will be described with reference to the block diagram of FIG.

The controller 22 has a position determination circuit 130.
An elapsed time measuring circuit 132 and a pressure control circuit 134.
, A motor control circuit 136, and a central processing circuit (hereinafter, C
138 and a read only memory (ROM)
140, a readable / writable memory (hereinafter referred to as RAM) 142, and an interface (hereinafter referred to as I / F)
It is composed of a circuit 144 and a set value storage circuit 146.

In the servo cylinder device 10 configured as described above, the work W is moved from the predetermined position L _O to the first position.
The operation of raising to the target position L _X will be described with reference to the flowchart of FIG.

First, the cylinder body 16 is arranged upright with the head cover 24 as an upper portion as described above, and further, compressed air for preventing the work W from falling is supplied to the rod cover side cylinder chamber 50. Moreover, since the disc brake mechanism 40 acts on the ball screw shaft 36, the work W does not drop and is stopped at the position L _O.

In such an initial state, a control start signal is sent from the keyboard via the I / F circuit 144 to the CPU 1
38 is input (step S1), the CPU1
38 outputs a switching signal to the electromagnetic switching valve 20,
The electromagnetic switching valve 20 is switched by this switching signal, compressed air is supplied from the compressed air supply source 12 to the brake cylinder 18, and the brake acting on the ball screw shaft 36 is released (step S2).

That is, the disc brake mechanism 40
Compressed air is supplied to the brake cylinder 18 of FIG. 1 to displace the piston 76 in the Z2 direction shown in FIG.
The disc brake mechanism 40 is deactivated by separating the braking member 78 from the ball screw shaft 36.

At this time, as described above, the rod cover side sheath
Compressed air that prevents the work W from falling is stored in the binder chamber 50.
Since it is supplied, the work W does not drop
Setting L _OHas stopped.

Next, the CPU 138 reads out data relating to the pressure in the rod cover side cylinder chamber 50 from the RAM 142, and outputs a signal corresponding to this data to the pressure control circuit 1.
It outputs to 34.

The electropneumatic regulator 14 based on the signal
Is controlled by the pressure control circuit 134 to increase the pressure in the rod cover side cylinder chamber 50 to the pressure P _A (step S
3) The pressure is gradually reduced based on the preset curve (see FIG. 8) (step S4). When the rod cover side cylinder chamber 50 is pressurized, the ball screw shaft 36 rotates and the work W rises (step S5).

In this case, the rod cover side cylinder chamber 50
When the pressure is increased, the piston 38 rises (Z1 direction in FIG. 3), and the piston rod 100 and the table 3 are further moved.
0 rises. At this time, the piston rod 100 and the non-rotating guide rod 106a via the table 30,
Since 106b is fixed, the ball screw shaft 36 rotates without rotating the piston 38.

The rotational force of the ball screw shaft 36 is transmitted to the servo motor 64 via a pulley 60, a timing belt 72 and a pulley 70 axially attached to the end portion on the head cover 24 side.
Is transmitted to the drive shaft 66 to rotate the drive shaft 66. The rotation amount of the drive shaft 66 is detected by the encoder 68 and output to the position determination circuit 130.
At 30, the displacement position of the work W is detected.

When the position determination circuit 130 determines that the detected position of the piston 38 has reached the set value L ₁ stored in the set value storage circuit 146 (step S6).
A signal indicating that the workpiece W has reached the set value L ₁ is output from the position determination circuit 130 to the motor control circuit 136 via the CPU 138.

A signal for rotationally driving the servo motor 64 in the positive direction by this signal is output from the motor control circuit 136 to the servo motor 64, and the servo motor 64 is rotationally driven in the positive direction at a predetermined speed (step S7). ),
The work W rises. At this time, the compressed air in the rod cover side cylinder chamber 50 has a pressure higher than that for supporting the static load of the work W, and therefore the servo motor 64 starts rotating with a small starting torque.

On the other hand, when it is determined in step S6 that the work W has reached the set value L ₁ , the CPU 13
A signal for starting the measurement of the elapsed time is output from 8 to the elapsed time measuring circuit 132. This signal causes the elapsed time measuring circuit 132 to start measuring the elapsed time from when the workpiece W reaches the set value L ₁ .

When the elapsed time reaches the set time t ₁ (step S8), the elapsed time measuring circuit 132 outputs a time elapsed signal to the pressure control circuit 134, and this signal causes the electropneumatic regulator 14 to operate. Pressure control circuit 1
Controlled by 34, the rod cover side cylinder chamber 50
Is controlled to a pressure P _O that balances the static load of the work W (step S9).

Therefore, after step S9, the work W is displaced upward only by the rotational torque of the servo motor 64.

Then, the displacement position of the work W is set to the second setting.
Position L₂The position determination circuit 130 determines whether or not
It is determined (step S10) that the work W is in the second setting position.
Setting L ₂Is reached, the position determination circuit 130 outputs the
The electromagnetic switching valve 20 is switched by the switching signal
Compressed air in the brake cylinder 18 is released to the atmosphere
(Step S11).

Therefore, the piston 76 is displaced in the Z1 direction in FIG. 4 by the elastic force of the coil spring 86, the braking member 78 is pressed against the brake disc 96, and the braking member 7 is pressed.
The brake disc 96 is clamped by 8, 90,
The ball screw shaft 36 stops rotating, and the work W stops rising (step S12).

The CPU 138 which has detected by the encoder that the displacement of the work W has stopped is the motor control circuit 1
A signal for stopping the rotation of the servo motor 64 is output to the motor 36, and the motor control circuit 136 stops the rotation of the servo motor 64 (step S13).

At this time, the work W is positioned and stopped at the first target position L _X due to the operation delay time generated in the electromagnetic switching valve 20, the brake cylinder 18, and the like.

As described above, the work W has the first target position L.
_XPositioned with high precision. In addition, the servo
At a predetermined time after the displacement of the work W by the data 64 is started.
Interval t ₁Compressed air and servo motor
Since the work W is lifted by the action of 64,
It is possible to use a motor with small power consumption.

Next, the operation of lowering and positioning the work W positioned at the first target position L _X to the second target position L _Y will be described with reference to the flowchart of FIG. 7.

When the control start signal is input (step S
21), compressed air is supplied to the brake cylinder 18 and the brake is released, as in step S2 described above (step S22).

At this time, the rod cover side cylinder chamber 50
Since air having a pressure that supports the static load of the work W is supplied to the work W, the work W does not drop and is stopped at the first target position L _X.

Next, the CPU 138 sends the pressure control circuit 1
Based on the signal output to 34, the pressure control circuit 134 outputs a pressure control signal to the electropneumatic regulator 14. After this signal, the rod cover side cylinder chamber 50 is controlled to a preset pressure, for example, atmospheric pressure (step S23), and then gradually pressurized based on a preset curve (see FIG. 8) (see FIG. 8). Step S2
4). Due to this pressure reduction, the ball screw shaft 36 rotates and the work W descends (step S25).

The rotation of the ball screw shaft 36 is detected by the encoder 68 and output to the position determination circuit 130, and the displacement position of the work W is set by the position determination circuit 130 to the set value L stored in the set value storage circuit 146. _It is determined whether or not the number has reached ₃ (step S26).

In this judgment, when it is judged that the displacement position of the work W has reached the set value L ₃ , the position judgment circuit 1
A signal indicating that the work W has reached the set value L ₃ is output from 30 to the motor control circuit 136 via the CPU 138, and a signal for rotationally driving the servo motor 64 in the reverse direction is based on this signal. Output from the circuit 136, the servo motor 64 rotates in the reverse direction at a predetermined speed to displace the work W downward (step S27).

At this time, the rod cover side cylinder chamber 50
Is below the pressure that can support the lowering of the work W, the servo motor 64 starts rotating with a small starting torque.

On the other hand, when it is determined in step S26 that the work W has reached the set value L ₃ , the CPU 1
A signal for starting the measurement of the elapsed time is output from 38 to the elapsed time measuring circuit 132. This signal causes the elapsed time measuring circuit 132 to start measuring the elapsed time from when the workpiece W reaches the set value L ₃ .

When the elapsed time reaches the set time t ₂ (step S28), the elapsed time measuring circuit 132
A time lapse signal is output from the pressure control circuit 134 to the pressure control circuit 1 by this signal.
Controlled by 34, the rod cover side cylinder chamber 50
Is controlled to a pressure P _O that balances the static load of the work W (step S29).

Therefore, after step S29, the work W is displaced downward only by the rotational torque of the servo motor 64.

Next, the position determination circuit 130 determines whether or not the displacement position of the work W has reached the next set value L ₄ (step S30). If the work W has reached the set value L ₄ , the position is determined. The electromagnetic switching valve 20 is switched by the switching signal output from the determination circuit 130, and the compressed air in the brake cylinder 18 is released to the atmosphere (step S31).

Therefore, similarly to the above-described step S11, the brake disc 96 is clamped by the braking members 78 and 90, the rotation operation of the ball screw shaft 36 is stopped, and the lowering of the work W is stopped (step S32).

Further, when the encoder 68 detects that the displacement of the work W has stopped, the CPU 138 outputs a signal for stopping the rotation of the servo motor 64 to the motor control circuit 136, and the motor control circuit 136 outputs the signal of the servo motor 64. The rotation is stopped (step S33).

At this time, the work W is stopped at the second target position L _Y due to the operation delay time generated in the electromagnetic switching valve 20, the brake cylinder 18 and the like.

As described above, according to this embodiment,
When the drive of the servo motor 64 is started, the work W is displaced by the action of the compressed air, so that the work W can start rotating with a small driving torque.

[0068]

In the positioning control method for the servo cylinder according to the present invention, the compressed air supplied to the cylinder chamber is used to quickly displace the workpiece to the vicinity of the target position, and then the motor is positioned to the target position. It is possible to obtain an effect that a heavy work can be positioned quickly and with high accuracy.

Further, since the static load of the work is held by the action of the compressed fluid supplied to the cylinder chamber, it is possible to use a servo motor having a small torque, and it is possible to miniaturize the servo motor. Play.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a servo cylinder device that implements a positioning control method for a servo cylinder according to the present invention.

FIG. 2 is a perspective explanatory view of a cylinder body in the embodiment shown in FIG.

3 is a partial cross-sectional explanatory view of a cylinder body in the embodiment shown in FIG.

4 is a partial cross-sectional explanatory view of a disc brake mechanism in the cylinder body shown in FIG.

5 is a block configuration diagram of a controller in the embodiment shown in FIG. 1. FIG.

6 is a flowchart illustrating an operation of positioning a work at a first target position in the servo cylinder device shown in FIG.

7 is a flowchart illustrating an operation of positioning a work at a second target position in the servo cylinder device shown in FIG.

8 is a timing chart explaining the operation of the flowcharts shown in FIGS. 6 and 7. FIG.

[Explanation of symbols]

10 ... Servo cylinder device 14 ... Electropneumatic regulator 16 ... Cylinder body 18 ... Brake cylinder 20 ... Electromagnetic switching valve 22 ... Controller 64 ... Servo motor 68 ... Encoder 130 ... Position determination circuit 132 ... Elapsed time measurement circuit 134 ... Pressure control circuit 136 ... Motor control circuit

Claims (2)

[Claims] 1. A piston rod attached to a piston of a cylinder, a ball screw engaging with the piston rod, and a motor for rotationally driving the ball screw, the pressure of air supplied to a cylinder chamber, A positioning control method in a servo cylinder for displacing the piston rod by the rotational force of the motor to position the work attached to the piston rod at a target position, wherein the work is performed by controlling the pressure in the cylinder chamber. A first step of displacing the workpiece to a predetermined position in the vicinity of a target position; and, when the work reaches the predetermined position, a motor is driven to rotate to rotate the motor and the air pressure in the cylinder chamber to move the work. The second step of continuing the displacement, and when a predetermined time has elapsed since the servo motor started to rotate, It comprises a third step of controlling the pressure of air in the cylinder chamber to a pressure for holding the static load of the work, and a fourth step of displacing the work only by the rotational force of the motor and positioning it at the target position. A positioning control method for a servo cylinder, comprising: 2. The method according to claim 1, wherein the fourth step is a step of energizing a brake mechanism for stopping the displacement of the work when the work reaches a preset position immediately before the target position. A positioning control method in a servo cylinder, comprising: