JPH07158603A - Reciprocating inversion system controlling method - Google Patents

Abstract

PURPOSE:To optimumly control shock at the time of inversion according to mass and velocity of a table. CONSTITUTION:A spring-center double-solenoid type shockless changeover valve 4 is arranged between a hydraulic actuator 1 in which inertial load is reciprocatively inverted and a pump 2. Current of one solenoid 20A of the valve 4, which is excited, is switched off by inversion signals due to a limit switch. A spool thereof is reset to a neutral position. After a specified time t3, current of the other solenoid 20B which is not excited is switched ON. The spool is moved to the opposite direction, and the hydraulic actuator 1 is inverted and driven.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating reversing drive system control method for shockless reciprocating reversing of an inertial load such as a table reciprocatingly driven by a hydraulic actuator or a reciprocating swinging body.

[0002]

2. Description of the Related Art As a reciprocating reversing drive system of this kind, for example, in the field of machine tools, there is a reversing drive system for a surface grinding machine table. The surface grinder table is designed to load the work and reciprocate left and right to grind the surface of the work into a flat surface. Therefore, the reciprocating speed of the table is constant and the table can be reversed without shock and in a short time. Required.

However, this surface grinding machine is different from other grinding machine tools in the field of machine tools, and the so-called NC control for controlling the machine tool by numerical information is the most delayed.
At present, the shockless switching valve provided between the hydraulic actuator for reciprocating the reciprocating motion of the table and the pump is merely controlled according to a predetermined operating program.

[0004]

However, in such a conventional reciprocating reversing drive system control method, since the shockless switching valve is always controlled in accordance with a predetermined operation program, the mass and speed of the table are reduced. Even if the shock at the time of hydraulic actuator reversal changes due to changes in the environmental temperature, etc., it is not possible to automatically change the damping characteristics of the shockless switching valve to respond to it and optimally control the shock. It was

Therefore, it is unavoidable to adjust so that the shock at the time of reversing the hydraulic actuator becomes appropriate at the time of switching the shockless switching valve under possible limit conditions, and the stop time at the time of reversing is too long under other conditions. There was a problem that productivity was hindered. The present invention has been made in view of the above points, and an object thereof is to always perform optimum control according to the state of inertial load.

[0006]

In order to achieve the above-mentioned object, the present invention is provided between a hydraulic actuator and a pump.
In the method of controlling a reciprocating reversing drive system, in which a shockless switching valve of a spring center / double solenoid type and a proportional throttle valve for flow rate control are provided to shocklessly reciprocate the inertial load by a reversal signal, the proportional throttle valve is used. Is supplied with a command current corresponding to the predetermined speed of the inertial load, and the reversal signal demagnetizes one solenoid in the excited state of the shockless switching valve to return the spool to the neutral position for a predetermined time. It is intended to provide a reciprocating reversing drive system control method in which the other solenoid, which is in a demagnetized state later, is excited and the spool is moved in the opposite direction to reversely drive the hydraulic actuator.

In the same reciprocating reversing drive system control method as described above, a command current corresponding to a predetermined speed of the inertial load is supplied to the proportional throttle valve, and the reversal signal is used to control the shockless switching valve. The current to one solenoid in the excited state is gradually decreased to return the spool to the neutral position, and then the current to the other solenoid is gradually increased to move the spool in the opposite direction to move the hydraulic actuator. It can also be driven in reverse. In this case, it is possible to continuously excite one solenoid to the other solenoid.

In these reciprocating reversal drive system control methods, it is more preferable to determine the time for which the spool of the shockless switching valve is held at the neutral position from the mass and speed of the inertial load.

[0009]

In the method of controlling the reciprocating reversing drive system according to the present invention, the time during which the spool is at the neutral position from the demagnetization of one solenoid of the shockless switching valve to the excitation of the other solenoid is achieved by performing the above. Can be changed to freely change the magnitude of shock when the hydraulic actuator is reversed.

Further, by gradually decreasing or gradually increasing the solenoid current of the shockless switching valve, the time during which the spool is in the neutral position can be arbitrarily set. In this case, the neutral degree can be obtained by changing the gradient of the solenoid current. You can adjust the time freely.

Furthermore, when the time during which the spool of the shockless switching valve is in the neutral position is obtained from the mass and speed of the inertial load, the shock when the hydraulic actuator is reversed is automatically generated even if the mass or speed is changed. It will always be possible to optimize.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. Prior to that, a schematic structure of a reciprocating reversing drive system for implementing this control method will be described with reference to FIG. .

In this system, between the hydraulic cylinder 1 which is a hydraulic actuator that reciprocally drives the table W which is an inertial load, and the pump 2, the shockless switching valve 4 and the pump 2 in three positions supply the hydraulic cylinder 1 to the hydraulic cylinder 1. A proportional direction flow rate control valve (hereinafter referred to as “proportional throttle valve”) 8 with an unloading function for controlling the flow rate is provided, and a controller 10 for controlling these is provided. In addition,
Reference numeral 9 in the drawing is a relief valve for preventing the circuit pressure from rising above a predetermined value.

The shockless switching valve 4 is provided with a pair of solenoids 20A and 20B on both sides of the valve body 11 as shown in FIG. 7, for example, and is opened by opening and closing each port in the valve body 11. A spool 12 for switching the path is slidably provided, and both ends of the spool 12 are pressed from both sides by a pair of centering springs 14A and 14B via centering washers 13A and 13B so that the spool 12 can be held at a neutral position shown in the figure. In this state, an open center type that communicates with all ports is used to reduce shock when the hydraulic cylinder 1 is reversed.

When a current is passed through the coil of the solenoid 20A on the left side, the fixed iron core 21A is excited to attract the movable iron core 22A, the movable iron core 22A moves to the right, and the spool 12 is pulled through the hollow push pin 23A. Solenoid 20
The flow path is switched by moving to the right against the urging force of the centering spring 14B on the B side to communicate the port P with the port A and the port B with the port T, respectively.
The table W is moved to the right through.

When the coil of the solenoid 20A is deenergized by de-energizing the coil, the spool 12 returns to the neutral position shown by the restoring force of the centering spring 14B on the solenoid 20B side. When the coil on the solenoid 20B side is energized in this state, the spool 12 moves leftward against the centering spring 14A to switch the flow path, and the port P is set to the port B and the port A is set to the port T.
And the table W is moved to the left via the hydraulic cylinder 1. When the coil is de-energized, the restoring force of the centering spring 14A returns the coil to the neutral position.

The movable iron core 22 is moved by the movement of the spool 12.
The pressure oil in the oil chambers 24A, 24B before and after A, 22B moves through the passages in the push pins 23A, 23B,
The moved pressure oil is supplied to the orifices 23Aa, 23Ab or 23Ba, 23B formed in the push pins 23A, 23B.
b in the intermediate oil chamber 25A, 26A or 25B, 26
It flows into B. Therefore, by appropriately determining the sizes of these orifices, the opening degree in the neutral state and the switching time can be set to required values, and the oil chamber cylinder 1
The shock at the time of reversing is relieved to form a hydraulic damping mechanism.

Further, FIG. 8 shows only the proportional throttle valve portion in the right half of the proportional throttle valve 8 with the unloading function,
Since the configuration of the switching valve section in the left half is similar to that of FIG. 7, its illustration and description are omitted, and the reference numerals of corresponding members other than the solenoid 40A are not suffixed with suffixes A and B, and are common to the left and right. It is shown. This proportional directional flow control valve 8 is equipped with solenoids 40 on both sides of a valve main body 31, slidably provided with a flow path switching spool 32 in the valve main body 31, and both ends of the spool 32 are provided with centering washers 33. It is pressed from both sides by a pair of centering springs 34 and is held at the neutral position in the figure.

Further, orifices 43a and 43b are respectively provided in the hollow push pin 43 which is driven by the movable iron core 42, and the spool 32 and the movable iron core 42 which is driven by the orifices 43a and 43b are moved in the left and right directions. A hydraulic damping mechanism is configured such that the pressure oil of No. 2 passes through the center hole 42a in the movable iron core 42 and the passage 43c in the push pin 43, is throttled by the orifices 43a, 43b, and flows out into the intermediate oil chambers 45, 46. is doing. Then, the responsiveness of the hydraulic damping mechanism of the proportional throttle valve 8 is set to the shockless switching valve 4
It is designed to be slower than the response of the hydraulic damping mechanism of.

As a result, the hydraulic cylinder 1 shown in FIG.
When is reversed, the secondary system vibration generated in the spool 32 of the proportional valve section can be stabilized by the influence of the change of the fluid force due to the fluctuation of the pressure oil flow rate and the flow rate, and the spool 32 moves due to the vibration. As a result, it is possible to eliminate the risk that the hydraulic cylinder 1 will not operate smoothly.

The proportional throttle valve 8 is a closed center type in which each port is closed at the neutral position. The right side of the proportional throttle valve 8 is a proportional type capable of linearly controlling the opening according to a command from the controller 10. With load function. The unloading function is not necessary when the table W is reciprocally driven by the hydraulic drive of the pump 2, but is used when the table W is manually moved.

Next, a method of controlling the reciprocating reversal drive system having the above-mentioned structure will be described. FIG. 1 is a sequence diagram showing a first control method of the shockless switching valve 4. In this control method, the solenoid current is supplied by a constant current circuit that is not easily affected by temperature, and one solenoid is turned ON → OFF and the other solenoid is turned OFF →
The time to turn on is variable.

When an inversion signal S as shown in FIG. 1A is issued by a limit switch which is turned on / off by the movement of the hydraulic cylinder 1 or the table W, the solenoid current I shown in FIG. As a result, the current to the one solenoid 20A that was in the excited state is cut off, and the demagnetized state is reached. As a result, the spool 12 is pressed to the left by the urging force of the centering spring 14B shown in FIG. 8 as indicated by the spool stroke ST in FIG. 8C, and the stroke is gradually linearized by the hydraulic damping mechanism described above. And stops at the neutral position C, which is even with the urging force of the other centering spring 14A.

After a predetermined timer time t3 from the demagnetization of the solenoid 20A, a solenoid current I is supplied to the solenoid 20B to be excited, and the spool 12 is gradually decelerated by the hydraulic damping mechanism against the urging force of the centering spring 14B. Move to the right linearly. Along with this, as shown in FIG. 1D, the spool opening Ap also changes and the neutral time t0 can be obtained, and the shock at the time of reversing the hydraulic cylinder 1 is alleviated during the neutral time t0.

The above is the control method in which the shockless switching valve 4 is controlled by turning on / off the solenoid current to vary the neutral time. In FIG. 2, the neutral time is varied by controlling the current of the shockless switching valve 4. FIG. 6 is a sequence diagram showing a second control method of the present invention, in which (a) is an inverted signal S by a limit switch, (b) is a solenoid current I of the shockless switching valve 4, and (c) is a spool. 12 degrees of opening Ap are shown, respectively. During the above operation of the shockless switching valve 4, the proportional throttle valve 8 is supplied with a command current corresponding to a predetermined speed.

When the hydraulic cylinder 1 shown in FIG. 6 and the table W which is driven by the hydraulic cylinder 1 reach the forward end or the backward end, and a limit switch (not shown) is turned on, as shown in FIG. When S is emitted, one solenoid 20A or 20B of the shockless switching valve 4 is demagnetized and the other solenoid 20B or 20A is excited. At this time, each solenoid current I is linearly changed as shown in FIG.

Along with this, the spool 12 of the shockless switching valve 4 moves, and the opening Ap thereof changes from one full opening Af1 to the neutral opening A0 as shown in FIG. The opening degree becomes Af2. The inclined portion between the full opening Af1 and Af2 of the shockless switching valve 4 and the neutral opening A0 indicates a switching intermediate state between the switching positions A and B and the neutral position C, and all ports are connected. During the neutral time t0 indicated by the neutral position C, the shock at the time of reversing the hydraulic cylinder can be absorbed.

The neutral time t0 is the solenoid current I of the shockless switching valve 4 shown in FIG. 2 (b).
It can be freely changed by changing the inclination angle α of. FIG. 3 is a sequence diagram similar to FIG. 2 showing a change state of the neutral time t0 when the inclination angle α is changed, and a line corresponding to the inclination angle α similar to FIG. 2 is a solid line,
When the line corresponding to the inclination angle α1 where the inclination is steep is shown by a one-dot chain line and the line corresponding to the inclination angle α2 where the inclination is gentle is shown by a two-dot chain line, the neutral time t of the neutral position C1 of the one-dot chain state is shown.
It can be seen that 0 ′ becomes shorter than the intermediate position t0 of the neutral position C shown by the solid line, and the neutral time t0 ″ of the neutral position C2 of the two-dot chain line state becomes longer than the intermediate time t0 of the neutral position C shown by the solid line.

As described above, since the neutral time t0 has a function of absorbing a shock when the hydraulic cylinder 1 is reversed, the mass of the inertial load of the table W or the proportional throttle valve portion of the proportional flow control valve 8 is used. It is possible to absorb the shock when the hydraulic cylinder 1 is reversed by changing the neutral time t0 according to the difference in the supply flow rate to the hydraulic cylinder 1 and appropriately selecting the neutral opening A0.

However, the position x of the hydraulic cylinder 1 and the time t
As can be seen from the diagram of FIG. 4 showing the relationship with the neutral opening A
By changing 0 or the neutral time t0, the overrun distance y of the hydraulic cylinder 1 after the inversion signal is issued may become long, or the bending portion Z generated at the time of inversion may make the hydraulic actuator slightly stop. .

Therefore, in order to bring the table 1 as close as possible to the most desirable "time-table position" diagram shown in FIG. It is necessary to make adjustments while observing the operating state of the table W so that the magnitude of shock at the time of reversal falls within an allowable range, and the immediacy at the time of reversal is made as good as possible.

The mid-switching time t1 in FIG. 2 is actually the time required to close the spool opening when the solenoid of the shockless switching valve 4 shown in FIG. 8 is off,
Since the switching intermediate time t2 is the time required to open the spool opening when the solenoid is on, there are some differences, but these are values that depend on the responsiveness determined by the design value of the shockless switching valve 4, The values cannot be electrically changed by the controller 10. However, since the shock and overrun values at the time of reversing the hydraulic cylinder 1 change depending on the switching intermediate times t1 and t2, their design values must be selected appropriately.

Further, the shock at the time of reversing the hydraulic cylinder 1 changes in accordance with changes in the mass and speed of the table W, the environmental temperature, etc., and these change the neutral time t0 which can be made variable by the controller 10. It can be adjusted freely. In particular,
The tilt angle α of the solenoid current I of the shockless switching valve 4 shown in FIG. 2B can be made variable by a trimmer for fine adjustment provided in the controller 10, and can be adjusted by the operator if necessary. Absent. Further, this makes it possible to sufficiently absorb the machine difference of the shockless switching valve.

Further, instead of leaving these to the operator's adjustment, it is also possible to use a sensor or the like for automatic adjustment. That is, the mass of the table W, the speed,
Acceleration, ambient temperature, etc. are detected by the respective sensors provided in the system, and the controller 10 causes the controller 10 to incline the angle α of the solenoid current I of the shockless switching valve 4 so that an appropriate shock, overrun or reversal speed can be obtained. To adjust the neutral time t0. By this adjustment, the intermediate switching times t1 and t2 are actually slightly changed, and the shock can be totally optimized.

FIG. 9 is a block diagram showing the various controls described above.
3 is a block diagram showing an example of a portion that controls the shockless switching valve 4 of the controller 10 of FIG. The maximum current supplied to each solenoid 20A, 20B of the shockless switching valve 4 is set by the maximum current setting device 52. The timing controller 50 is a neutral time setting device that uses a microcomputer, and inputs the reversal signal S from a limit switch (not shown), the mass of the table W and the table speed (proportional to the opening of the throttle valve) in advance. The optimum neutral time is set by reading the table data stored in the setting table memory (ROM, etc.) 51 calculated for various table masses and table speeds.

As a result, when the first control method shown in FIG. 1 is carried out, the current control circuit 54,
55 is not necessary, but if there is this, the current I is generated by the control signals a and b from the timing controller 50.
While keeping both a and Ib at the maximum values, the switches SWa and SWb of the switching circuit 53 are turned on.
Control off timing. For example, solenoid 20A
Side switch SWa from on to off and solenoid 20B
FIG. 1 shows the timing of turning on the switch SWb on the side from off.
As shown in (b) above, if the control is performed so that the timer time t3 is delayed, the optimum neutral time can be obtained.

When the second control method shown in FIG. 2 is carried out, the switches SWa and SWb of the switching circuit 53 for turning on / off the current to the solenoids 20A and 20B.
Is always turned on during system operation by a signal from the timing controller 50 so that a constant maximum current set by the maximum current setting device 52 can be made to flow through the coils of the solenoids 20A, 20B by the constant current amplifiers 56, 57. This switching circuit 53 and constant current amplifier 5
Current control circuits 54 and 55 are interposed between 6 and 57, and control signals a and b from the timing controller 50 are provided.
Thus, the currents Ia and Ib supplied by the constant current amplifiers 56 and 57 can be changed from zero to the set maximum value.

Therefore, for example, from a state in which the current control circuit 54 controls the current Ia flowing to the solenoid 20A to the maximum value and the current control circuit 55 controls the current Ib flowing to the solenoid 20B to zero, from a limit switch (not shown). When the inversion signal S is input to the timing controller 50, the optimum hollow time is set there and the control signals a and b are output to the current control circuits 54 and 55. Thereby, first, the current Ia supplied to the solenoid 20A is linearly decreased, and the current Ib supplied to the solenoid 20B is linearly increased from zero at the timing when it becomes zero, as shown in (b) of FIG. Control the solenoid current I.

All of the above have described the control method of the shockless switching valve 4, but for the control of the proportional throttle valve 8, it is sufficient to supply a command current corresponding to the predetermined speed of the table W, and the control method thereof. Since this is the same as the method generally used in the past, its description is omitted.

In the above control method, the mass of the table W and the moving speed are input to the timing controller 50 as variable elements for setting the neutral time, but the neutral time changes depending on the environmental temperature and the like in addition to these elements. Because
In addition to the above variable elements, if all other variable elements are detected by the sensor and input to the timing controller 50, further fine grained control becomes possible.

In the above control method, the present invention has been described for the case where the table that reciprocates linearly, such as a surface grinder, is reversely driven and controlled by the hydraulic cylinder. However, the present invention is not limited to this, and a swinging motion is possible. Even when the rotating load is reciprocally rotated by a rocking cylinder or the like, it can be controlled without any trouble.

[0042]

As described above, the reciprocating reversal drive system control method according to the present invention is provided with the shockless switching valve and the proportional throttle valve between the hydraulic actuator and the pump, and the proportional throttle valve is provided with an inertial load. Since the command current corresponding to the predetermined speed is supplied, the speed of the hydraulic actuator can be electrically linearly controlled by remote control to move the inertial load at the predetermined speed.

Since one solenoid of the shockless switching valve is demagnetized and the other solenoid is excited after a predetermined time, the neutral time when the spool is in the neutral position is controlled by appropriately setting the time. The shock of the hydraulic actuator is absorbed within this neutral time, and smooth reversal becomes possible.

In a similar control method, in which one solenoid current of the shockless switching valve is gradually reduced to a neutral state and then the other solenoid current is gradually increased, the gradient of the solenoid current is changed. By doing so, the neutral time can be freely adjusted. At this time, if the excitation from one solenoid to the other solenoid is continuously performed, the shock at the time of reversal can be alleviated while the reversal time of the hydraulic actuator is relatively short.

Furthermore, when the neutral time of the shockless switching valve is calculated from the mass and speed of the inertial load, the data can be used to obtain an optimum shock for any load. It becomes possible to absorb machine differences.

[Brief description of drawings]

FIG. 1 is a sequence diagram showing a first control method according to the present invention.

FIG. 2 is a sequence diagram showing a second control method according to the present invention.

FIG. 3 is a sequence diagram showing a neutral time varying method for switching the same.

FIG. 4 is a diagram similarly showing a hydraulic cylinder reversal state at the time of switching.

FIG. 5 is a diagram showing a relationship between a desired time and a table position at the time of switching.

FIG. 6 is a hydraulic circuit diagram showing a reciprocating reversal drive system embodying the present invention.

FIG. 7 is a sectional view showing a specific structure of the shockless switching valve.

FIG. 8 is a sectional view showing the right half of the proportional directional flow control valve with an unloading function.

9 is a block diagram showing a configuration example of a portion that controls a shockless switching valve 4 of the controller in FIG.

[Explanation of symbols]

 1: Hydraulic cylinder (hydraulic actuator) 2: Pump 4: Shockless switching valve 8: Proportional directional flow control valve with unloading (proportional throttle valve) 10: Controller 12: Spool (switching valve) 20A, 20B: Solenoid (switching valve) ) 40: Solenoid (proportional throttle valve) 50: Timing controller (neutral time setting device) 51: Setting table memory 52: Maximum current setting device 53: Switching circuit 54, 55: Current control circuit 56, 57: Constant current amplifier

Claims (4)

[Claims] 1. Between the hydraulic actuator and the pump,
A reciprocating reversing drive system control method, wherein a spring center / double solenoid type shockless switching valve and a proportional throttle valve for flow rate control are provided to shocklessly reciprocally reciprocate an inertial load by a reversal signal, wherein the proportional throttle valve is used. Is supplied with a command current corresponding to a predetermined speed of the inertial load, and one solenoid in the excited state of the shockless switching valve is demagnetized by the reversal signal to return the spool to the neutral position for a predetermined time. A reciprocating reversal drive system control method, characterized in that the other solenoid in a demagnetized state is subsequently excited to move the spool in the opposite direction to reversely drive the hydraulic actuator. 2. Between the hydraulic actuator and the pump,
A reciprocating reversing drive system control method, wherein a spring center / double solenoid type shockless switching valve and a proportional throttle valve for flow rate control are provided to shocklessly reciprocally reciprocate an inertial load by a reversal signal, wherein the proportional throttle valve is used. Is supplied with a command current corresponding to the predetermined speed of the inertial load, and the current to one solenoid in the excited state of the shockless switching valve is gradually reduced by the reversal signal to return the spool to the neutral position. After that, the current to the other solenoid in the demagnetized state is gradually increased, and the spool is moved in the opposite direction to reversely drive the hydraulic actuator. 3. The reciprocating reversing drive system control method according to claim 2, wherein excitation from one solenoid of the shockless switching valve to the other solenoid is continuously performed. Control method. 4. The reciprocating reversing drive system control method according to claim 1, wherein the time for holding the spool of the shockless switching valve at a neutral position is:
A reciprocating reversal drive system control method, which is obtained from the mass of the inertial load and the moving speed.