JP3265020B2 - Servo valve controller for hydraulic servo system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servo valve control device for a hydraulic servo system, and more particularly to a servo valve control device for feedback-controlling the operation of a servo valve.

[0002]

2. Description of the Related Art Generally, in a hydraulic servo system of a feedback control system, when a positioning module receives an operation command, the positioning module gives a spool opening command to a servo valve control device, and the servo valve control device is controlled accordingly. When the device drives the servo valve, the flow rate of the hydraulic pressure to the hydraulic cylinder device is controlled, and the displacement of the piston is generated by controlling the flow rate of the hydraulic pressure to the hydraulic cylinder device. The piston displacement is fed back to the positioning module.

[0003]

In the hydraulic servo system of the feedback control system as described above, for example, in order to drive a ram by a nibbling pattern in a punch press, a piston of a hydraulic cylinder device is moved from an initial position to a ram. When displacing to the predetermined control target position that is the bottom dead center position and then reciprocating to return the piston to the original initial position, if the loop gain of the hydraulic servo system is increased, time delay, control target value On the other hand, while the deviation decreases, the deviation before the piston returns to the original initial position increases, and an oil hammer phenomenon occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the conventional hydraulic servo system, and has a high-speed, high-precision hydraulic servo system while reducing the vibration by reducing the oil hammer phenomenon. It is an object of the present invention to provide a servo valve control device that can realize the above.

[0005]

SUMMARY OF THE INVENTION The present invention relates to the above-described problems.
It was made in view of the title, linear drive magnet
Quantitatively changes the spool opening according to the current applied to the spool
And a position for detecting the spool position.
Linear servo valve with detector and spool opening finger
Spool output command signal output from the
Bias due to the difference from the position feedback signal of the position detector
Input the difference and according to the input gain setting signal
The control deviation is amplified with the gain set in
Variable gain spool position output that is output as a command signal
And a speed finger output from the spool position amplifier.
Command signal and the position feedback signal.
The control deviation due to the difference from the speed feedback signal
And amplify the linear drive valve of the linear servo valve.
A current amplifier that supplies valve drive current to
In the servo valve control device of the hydraulic servo system
A position feedback signal from the position detector and the speed
Input the feedback signal
The signal is used to supply hydraulic pressure by the linear servo valve.
Fixie of hydraulic cylinder device that supply and discharge is performed quantitatively
Return to near zero after the displacement reaches its maximum from zero
The piston displacement from the area and the point returning to near this zero point
Determine the area up to the zero point, and close to the zero point
Gain to set the gain to a large value in the return area
A setting signal is output to the spool position amplifier, and the zero point is output.
Set the gain to a small value in the region before returning to
Output a gain setting signal to the spool position amplifier.
Provided with a gain selection circuit for the purpose.

[0006]

[0007]

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

FIG. 1 shows a basic configuration of a servo valve control device for a hydraulic servo system according to the present invention. This hydraulic servo system has a servo valve 1 to be controlled, a gain setting means 3, and a gain setting signal generating means 5.

The servo gain setting means 3 is provided with a control deviation E due to a difference between the target value R and the opening degree of the servo valve 1 detected by the position detector, that is, the control amount Y of the servo valve 1, and inputs a gain. Gain K according to setting signal Ks
To output the manipulated variable signal U to the servo valve 1.

The gain setting signal generating means 5 receives the control amount Y of the servo valve 1, generates a gain setting signal Ks that changes according to a predetermined characteristic according to the control amount Y, and generates the gain setting signal Ks. Servo gain setting means 3
Output to

As a result, the gain K of the hydraulic servo system changes according to a predetermined characteristic according to the control amount Y of the servo valve 1.

FIGS. 2 and 3 show an embodiment in which a hydraulic servo system including a servo valve control device according to the present invention is applied to a ram drive device of a turret punch press. As shown in FIG. 2, the turret punch press holds a punch 13 on an upper turret disk 11 and a die 17 on a lower turret disk 15, respectively. The punch 13 is located just below the striker 21 connected to the ram 19 at the press position, and is pressed by the striker 21.

The ram 19 is connected to a piston rod 25 of a hydraulic cylinder device 23, and is reciprocated vertically by the hydraulic cylinder device 23. The hydraulic cylinder device 23 is a backward-acting hydraulic cylinder device having cylinder chambers 29 and 31 on both sides of the piston 27, respectively.
When the hydraulic pressure is supplied to the cylinder chamber 31, the ram 19
Is driven to rise.

The supply and discharge of the hydraulic pressure to and from the cylinder chambers 29 and 31 are quantitatively performed by a linear servo valve 33.

The linear servo valve 33 is an electromagnetically actuated linear servo valve, and is configured to quantitatively change the spool opening in accordance with the current supplied to the linear drive magnet 35. A hydraulic pressure is supplied from a hydraulic supply system including a pressure regulating valve 39, and the cylinder chamber 29,
The flow rate of the hydraulic pressure supplied to 31 is quantitatively controlled.

The control of the current applied to the linear drive magnet 35 of the linear servo valve 33 is performed by a servo valve control device 41.

As shown in FIG. 3, the servo valve control device 41 has a spool opening command generation unit 43, a spool position amplifier 45, and a current amplifier 47.

The spool opening command generating section 43 generates a spool opening command signal and outputs the spool opening command signal to a combining point 49. The adding point 49 is connected to the spool opening command signal and the linear servo valve 33. A control deviation due to a difference from a position feedback signal indicating the spool position of the linear servo valve 33 detected by the provided position detector 51 is output to the spool position amplifier 45.

The spool position amplifier 45 is a variable gain type amplifier, sets a gain in accordance with the input gain setting signal, amplifies the control deviation with the gain, and adds it as a speed command signal to output to the matching point 53. It has become.

An addition point 53 is used to determine a control deviation due to a difference between a speed command signal and a speed feedback signal output from a differentiator 55 for differentiating the position feedback signal.
7 is output.

The current amplifier 47 amplifies the input control deviation with a predetermined amplification and supplies a valve drive current to the linear drive magnet 35 of the linear servo valve 33.

The gain setting signal input to the spool position amplifier 45 is output from a gain selection circuit 57. The gain selection circuit 57 receives a position feedback signal from the position detector 51 and a speed feedback signal from the differentiator 55, and detects the piston displacement of the hydraulic cylinder device 23 from these signals, as shown in FIG. As described above, in the reciprocating drive of the ram 19, the piston displacement becomes maximum from the zero point (initial position) and then returns to near the zero point, and the piston displacement returns to the zero point from the point returning to near the zero point. The area B until returning is determined, and the area A is determined.
In step (b), a gain setting signal for setting the gain to a relatively large value is output to the spool position amplifier 45, and in region B, a gain setting signal for setting the gain to a relatively small value is output to the spool position amplifier 45. It is configured to be.

According to the above description, in the reciprocating drive of the ram 19, in the area A where the piston displacement becomes maximum from the zero point (initial position) and then returns to near the zero point.
The gain selection circuit 57 outputs a gain setting signal for setting the gain to a relatively large value to the spool position amplifier 45,
As a result, in this area A, the gain of the spool position amplifier 45 is set to a relatively large value. As a result, in the area A, the time delay and the deviation from the control target value become small values, the quick response and high accuracy are maintained, and the ram 19 can be driven at high speed.

On the other hand, in a region B from the point where the piston displacement returns to near the zero point to the point where the piston displacement returns to the zero point, the gain of the spool position amplifier 45 is switched to a relatively small value. This prevents the occurrence of the oil hammer phenomenon in the region B.

FIG. 4A shows the change in the speed of the spool of the linear servo valve 33 and the spool displacement under the above-described gain adjustment, and FIG. 4B shows the hydraulic cylinder device 23 at this time. 3 shows the piston displacement characteristics of FIG.

That is, in the nibbling process, for example, the gain is increased as shown by a solid line in FIG. 5 for the first and second shots, and the clamped work is moved during the transition from the first shot to the second shot. In this case, the gain can be switched by the gain selection circuit 57 so that the gain becomes small as shown by a dotted line. Therefore, the vibration becomes low during the nibbling process, and the vibration noise can be reduced.

Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to these embodiments, and various embodiments can be made within the scope of the present invention. Some will be apparent to those skilled in the art. In FIG. 1, the gain setting signal generation means 5 may be provided outside in advance without taking in feedback of the control amount of the servo valve 1 as shown by a two-dot chain line.

[0028]

As will be understood from the above description,
In the present invention, the gain selection circuit 57
The position of the position detector 51 provided in the servo valve 33
Differentiated speed of feedback signal and position feedback signal
Degree feedback signal, the linear servo valve
33 in the hydraulic cylinder device 23 controlled by
After the piston displacement reaches the maximum from the zero point,
Returned to the area A or returned to near the zero point
It is determined whether or not the area B is from the point to the return to the zero point.
In the area A, the gain is large, and in the area B,
Goes to the spool position amplifier 45 to set the gain small.
Outputs the gain setting signal, and based on this gain setting signal
Speed command signal is output by the gain set
Therefore, the piston displacement of the hydraulic cylinder device 23 is
Oil hammer phenomenon that easily occurs when returning to zero and stopping
Can be suppressed from occurring, as described above.
Such a conventional problem can be solved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a servo valve control device for a hydraulic servo system according to the present invention.

FIG. 2 is a configuration diagram of a main part showing an embodiment when a hydraulic servo system including a servo valve control device according to the present invention is applied to a ram drive device of a turret punch press.

FIG. 3 is a block diagram showing an embodiment of a servo valve control device when a hydraulic servo system including the servo valve control device according to the present invention is applied to a ram drive device of a turret punch press.

4 (a) shows a change in spool speed and a spool displacement of a linear servo valve under gain adjustment by a servo valve control device according to the present invention, and FIG. 4 (b) shows a piston displacement of a hydraulic cylinder device at this time. It is a graph which shows a characteristic.

FIG. 5 is a graph showing a relationship between a spool opening degree and a piston displacement in a hydraulic servo system in nibbling processing.

[Explanation of symbols]

 Reference Signs List 1 servo valve 3 gain setting means 5 gain setting signal generating means 13 punch 17 die 19 ram 21 striker 23 hydraulic cylinder device 33 linear servo valve 41 servo valve control device 43 spool opening command generating unit 45 spool position amplifier 47 current amplifier 51 position Detector 57 Gain selection circuit

Continuation of the front page (56) References JP-A-51-13093 (JP, A) JP-A-48-19988 (JP, A) JP-A-56-80511 (JP, A) JP-A-52-79185 (JP, A) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F15B 13/043 B30B 15/18 F15B 9/09

Claims (1)

(57) [Claims] 1. A linear drive magnet (35)
Quantitatively changes the spool opening according to the current obtained
Position detection configured to detect the spool position
A linear servo valve (33) having a device (51);
Spool output from pool opening command generator (43)
Opening command signal and position feed of the position detector (51)
Input the control deviation due to the difference with the back signal,
With the gain set in accordance with the input gain setting signal.
To amplify the control deviation and output it as a speed command signal
A variable gain type spool position amplifier (45);
Speed command signal output from pool position amplifier (45)
And the velocity obtained by differentiating the position feedback signal
Input and amplify control deviation due to difference with feedback signal
Linear drive of the linear servo valve (33)
A current source that supplies a valve drive current to the magnet (35)
Servo valve system for hydraulic servo system with pump (47)
In the control device, a position buffer from the position detector (51) is provided.
Feedback signal and the speed feedback signal.
And the two feedback signals cause the linear
-Quantitative supply and discharge of hydraulic pressure by the valve (33)
Piston displacement of the hydraulic cylinder device (23)
An area that returns to near the zero point after reaching the maximum from the zero point
(A) and the piston displacement from the point near this zero point
Is determined to be a region (B) until the point returns to the zero point,
In the region (A) that returns to the upper limit, increase the gain
Set the gain setting signal to the spool position amplifier (4
5), and in the region (B) before returning to the zero point
The gain setting signal to set the gain to a smaller value.
Gain selection for output to spool position amplifier (45)
A servo valve control device for a hydraulic servo system, comprising a selection circuit (57) .