JP6414196B2 - Hydraulic device - Google Patents

Description

  The present invention relates to a hydraulic device that reciprocates a piston of a hydraulic cylinder.

  A hydraulic device that reciprocates a piston of a hydraulic cylinder is used to reciprocate a table of a surface grinding machine as disclosed in, for example, Patent Document 1. That is, in the surface grinding machine equipped with this hydraulic device, the cylinder rod is connected to the table, and the table is driven by the rod connected to the reciprocating piston.

  The hydraulic device described above reciprocates the piston by alternately repeating a moving operation that moves the piston of the cylinder at a constant speed and a reversing operation that reverses the moving direction of the piston.

  When the cylinder is in a moving operation, the control valve that controls the cylinder is in a forward or backward movement state, and when the cylinder is in a reverse operation, the control valve is in a switching state. Further, the higher the current value of the solenoid that drives the control valve, the faster the moving speed of the cylinder, and the smaller the current value of the solenoid, the slower the moving speed of the cylinder.

  In the hydraulic apparatus disclosed in Patent Document 1 that operates as described above, an all-port closed type that closes all ports in a switching state in which the piston is reversed is adopted as the control valve.

JP-A-9-216136

  However, in the hydraulic device described in Patent Document 1, when the piston moving at a constant speed is reversed, the current flowing through the solenoid that drives the piston is set to zero in order to stop the piston. As described above, when the piston is reversed with the current flowing through the solenoid being zero, the speed gradient at the time of the deceleration of the piston is increased, and there is a problem that the shock caused by the reversing operation of the piston is increased.

  Specifically, the control valve of Patent Document 1 employs an all-port closed type that closes all ports in a switching state in which the piston is reversed. As a result, when the control valve is switched to the switching state, the port for discharging the liquid from the cylinder is closed, and due to the inertial force of the piston, the pipe connecting the cylinder and the port becomes high pressure, causing the piston to stop suddenly. At the same time, the port that supplies the liquid to the cylinder is closed, and the pipe connecting the cylinder and the port is evacuated due to the inertial force of the piston, which facilitates the sudden stop of the piston. Thus, the sudden stop of the piston increases the shock caused by the reversing operation of the piston.

  Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to provide a hydraulic device capable of suppressing a shock caused by a reversing operation of a piston.

The hydraulic device according to the first invention is
A cylinder for reciprocating a member;
A pump for supplying liquid to the cylinder;
A control valve disposed between the cylinder and the pump;
The cylinder has a first space to which liquid is supplied when the member is moved forward, and a second space to which liquid is supplied when the member is moved backward,
The control valve is
A first port in communication with the first space, a second port in communication with the second space, a supply port to which liquid is supplied from the pump, and a discharge port for discharging the liquid,
When the current value of the first solenoid is equal to or greater than a predetermined value, the forward movement state of communicating the supply port and the first port and communicating the second port and the discharge port;
When the current value of the second solenoid is equal to or greater than a predetermined value, a return state in which the supply port communicates with the second port and the first port communicates with the discharge port;
A switching state in which when the current value of the first solenoid and the current value of the second solenoid are smaller than a predetermined value, the supply port is shut off and the first port, the second port, and the discharge port are communicated with each other; Can take.

In the present invention, when the current value of the first solenoid and the current value of the second solenoid become smaller than a predetermined value, that is, without lowering the current value to zero, the control valve is switched to reverse the cylinder. Thereby, the speed gradient at the time of deceleration of a cylinder can be made small, and the shock resulting from the inversion operation | movement of a cylinder can be suppressed.
The predetermined value of the current value of the first solenoid and the predetermined value of the current value of the second solenoid are called reverse bias.

  Specifically, in the switching state of the control valve according to the present invention, the supply port is shut off and the first port, the second port, and the discharge port are communicated. Thereby, when the control valve is switched to the switching state, the second port and the discharge port communicate with each other. Accordingly, since the liquid in the second space is discharged through the second port, the pipe connecting the second space and the second port does not become high pressure, and the cylinder is prevented from suddenly stopping to prevent the cylinder from being stopped. Smooth inversion is possible. At the same time, since the first port and the discharge port communicate with each other, the liquid can be supplied to the first space through the first port, and the tube connecting the first space and the first port can be prevented from being evacuated. Smooth reversal of the cylinder can be promoted. By smoothly reversing the cylinder, a shock caused by the reversing operation of the cylinder can be suppressed.

  Therefore, even if the predetermined values of the current value of the first solenoid and the current value of the second solenoid during the reversing operation of the cylinder are increased, the shock caused by the reversing operation of the cylinder can be suppressed.

The hydraulic device according to the second invention is
The member moves forward at a predetermined speed, then reverses with a predetermined reversal time, and starts returning at a predetermined speed,
The predetermined value and the predetermined inversion time are controlled to be interlocked.

  In the present invention, control is performed so that a predetermined value of current and a predetermined inversion time are interlocked. In a hydraulic device, the adjustment at the time of cylinder reversal is usually desired to reduce the reversal shock or to be reversed in a short time, and it is desired that the adjustment between the two can be freely performed.

  In order to reduce the reversal shock, the reversal time is lengthened and the cylinder is decelerated to a low speed and then reversed. This is achieved by increasing the inversion time and decreasing the predetermined value of the current.

In order to invert in a short time, it is conceivable to shorten the inversion time. However, if the predetermined value of the current is small, the speed gradient becomes large and the shock increases. In order to prevent this, if the predetermined value of the current is increased, the velocity gradient is reduced and the shock can be suppressed. That is, short-time inversion is achieved by shortening the inversion time and increasing the predetermined value of the current.
As described above, when the inversion time and the predetermined value of the current are linked, adjustment during inversion can be freely performed.

A hydraulic device according to a third invention is
The predetermined value and a predetermined inversion time are controlled simultaneously.

  In the present invention, since the predetermined value of the current and the predetermined inversion time are controlled at the same time, for example, the user can easily adjust the operation at the time of cylinder inversion only by changing the angle of one potentiometer.

  In the first invention, when the current value of the first solenoid and the current value of the second solenoid become smaller than a predetermined value, that is, without lowering the current value to zero, the control valve is switched to reverse the cylinder. . Thereby, the speed gradient at the time of deceleration of a cylinder can be made small, and the shock resulting from the inversion operation | movement of a cylinder can be suppressed.

  Specifically, in the switching state of the control valve according to the present invention, the supply port is shut off and the first port, the second port, and the discharge port are communicated. Thereby, when the control valve is switched to the switching state, the second port and the discharge port communicate with each other. Accordingly, since the liquid in the second space is discharged through the second port, the pipe connecting the second space and the second port does not become high pressure, and the cylinder is prevented from suddenly stopping to prevent the cylinder from being stopped. Smooth inversion is possible. At the same time, since the first port and the discharge port communicate with each other, the liquid can be supplied to the first space through the first port, and the tube connecting the first space and the first port can be prevented from being evacuated. Smooth reversal of the cylinder can be promoted. By smoothly reversing the cylinder, a shock caused by the reversing operation of the cylinder can be suppressed.

  In the second invention, control is performed so that a predetermined value of current and a predetermined inversion time are interlocked. Thereby, when it is desired to reduce the reversal shock at the time of cylinder reversal or when it is desired to reverse the rotation in a short time, the distance between the two can be freely adjusted.

  In the third invention, since the predetermined value of the current and the predetermined inversion time are controlled at the same time, the user can easily adjust the operation at the time of cylinder inversion only by changing the angle of one potentiometer, for example.

1 is a schematic configuration diagram of a hydraulic device according to an embodiment of the present invention. It is the elements on larger scale which show a potentiometer. It is a table | surface which shows the command signal to the control valve which a potentiometer memorize | stores. It is a graph which shows operation | movement of a hydraulic apparatus when a potentiometer is set to A point. It is a graph which shows operation | movement of a hydraulic apparatus when a potentiometer is set to B point.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, the hydraulic device 20 drives a table 11 that constitutes a part of the surface grinding machine 10. In the surface grinding machine 10, for example, a workpiece 12, which is a member to be ground by a rotating grindstone, is placed on a table 11 and reciprocates horizontally in the horizontal direction together with the table 11. The table 11 is connected to a cylinder 21 described later of the hydraulic device 20.

  The hydraulic device 20 includes a cylinder 21, a pump 31, a control valve 40, and a valve control unit 51. The hydraulic device 20 uses oil as a liquid.

  The cylinder 21 is a double-acting double rod cylinder, and reciprocates the workpiece 12 via the table 11. The cylinder 21 includes a cylinder body 22, a piston 23, and a rod 24. The cylinder body 22 is formed in a cylindrical shape whose both ends are closed. The rod-shaped rod 24 is arranged coaxially with the cylinder body 22 and penetrates the cylinder body 22.

  The piston 23 is connected to the rod 24 and accommodated in the cylinder body 22, and partitions the internal space of the cylinder body 22 into a first space 27 and a second space 28. The first space 27 is supplied with liquid when the work 12 is moved forward. The second space 28 is supplied with liquid when the workpiece 12 is moved backward.

  The pump 31 is a rotary pump, is driven by a motor (not shown), and rotates at a constant rotational speed. The pump 31 is connected to a tank 32 that stores liquid and is connected to a control valve 40. As a result, the pump 31 supplies the liquid in the tank 32 to the cylinder 21 via the control valve 40.

  The control valve 40 according to the present invention is an electromagnetic proportional switching valve that is disposed between the cylinder 21 and the pump 31 and includes a first port 42, a second port 43, a supply port 44, and a discharge port 45. Further, the control valve 40 changes the flow rate of the liquid supplied from the pump 31 to the cylinder 21.

  The first port 42 is connected to the first space 27 of the cylinder 21 via the first pipe 58, and the second port 43 is connected to the second space 28 of the cylinder 21 via the second pipe 59. The supply port 44 is connected to the pump 31 to supply liquid, and the discharge port 45 is connected to the tank 32 to discharge liquid.

  The control valve 40 includes a valve body 41, a first solenoid 46 and a second solenoid 47 that drive the valve body 41, and a first spring 48 and a second spring 49 that press the valve body 41 to a neutral position (switching state). And have. The control valve 40 is connected to the valve control unit 51 and is operated by a command from the valve control unit 51. The valve control unit 51 includes a potentiometer 52 shown in FIG.

  The potentiometer 52 rotates the knob 53 between the points A and B to fix it at a predetermined position. As a result, a reversal time of a cylinder 21 (piston 23), which will be described later, and a bias current that is a reverse bias corresponding to the reversal time of the cylinder 21 are continuously changed (see FIG. 3).

  When the first solenoid 46 is energized and the current value of the first solenoid 46 is equal to or greater than a predetermined value (bias current), the valve body 41 moves to the right side in FIG. In the forward movement state, the first port 42 communicates with the supply port 44 and the second port 43 communicates with the discharge port 45.

  When the control valve 40 is moved forward, the liquid is supplied from the pump 31 to the first space 27 of the cylinder 21, and the liquid in the second space 28 of the cylinder 21 is discharged to the tank 32. As a result, the piston 23 of the cylinder 21 and the table 11 of the surface grinding machine 10 move in the right direction. Further, as the value of the current flowing through the first solenoid 46 increases and the flow rate of the liquid flowing into the first space 27 and the flow rate of the liquid flowing out of the second space 28 increase, the piston 23 (cylinder 21) and the table 11 The movement speed of will be faster.

  When the second solenoid 47 is energized and the current value of the second solenoid 47 is equal to or greater than a predetermined value (bias current), the valve element 41 moves to the left side in FIG. In the reverse movement state, the second port 43 communicates with the supply port 44 and the first port 42 communicates with the discharge port 45.

  When the control valve 40 is in the backward movement state, the liquid is supplied from the pump 31 to the second space 28 of the cylinder 21, and the liquid in the first space 27 of the cylinder 21 is discharged to the tank 32. As a result, the piston 23 and the table 11 move leftward. In addition, as the value of the current flowing through the second solenoid 47 increases and the flow rate of the liquid flowing into the second space 28 and the flow rate of the liquid flowing out of the first space 27 increase, the piston 23 (cylinder 21) and the table 11 Increases movement speed.

  When the value of the current flowing through the first solenoid 46 and the second solenoid 47 is smaller than a predetermined value (bias current), the valve body 41 is switched (neutral position). When the control valve 40 is switched, the table 11 stops. In the switching state, the supply port 44 is shut off, and the first port 42, the second port 43, and the discharge port 45 are communicated. Thereby, even if the control valve 40 is in the switching state, the liquid in the first space 27 can be discharged from the first port 42 via the discharge port 45.

  Hereinafter, the operation of the hydraulic apparatus 20 having the above configuration will be described. At this time, the potentiometer 52 is fixed at the point A, and the command signal to the control valve 40 is set to the time L1 = 10 and the bias current Ab1 = 1 required for the reversal of the piston 23.

  The surface grinding machine 10 performs an operation of repeatedly reciprocating the table 11 in order to grind the workpiece 12. For this reason, the hydraulic device 20 that drives the table 11 alternately and repeatedly performs a moving operation for moving the piston 23 at a predetermined set speed and a reversing operation for reversing the moving direction of the piston 23. In addition, the hydraulic device 20 during the reversing operation sequentially performs deceleration, stop, and acceleration of the piston 23. The cylinder 21 (piston 23), the table 11, and the workpiece 12 move integrally.

  In the hydraulic device 20, the speed of the cylinder 21 is controlled by adjusting the current flowing through the control valve 40 that drives the cylinder 21. Specifically, the higher the current value of the first solenoid 46 that drives the cylinder 21 and the current value of the second solenoid 47, the faster the moving speed of the cylinder 21, and the current value of the first solenoid 46 and the current value of the second solenoid 47 increase. The smaller the current value, the slower the moving speed of the cylinder 21.

  During the moving operation, the piston 23 moves at a predetermined set speed, and as a result, the table 11 moves at the set speed. The moving speed of the table 11 is a parameter that the user adjusts according to the material of the workpiece 12 and the processing conditions.

  As described above, the moving speed of the piston 23 changes according to the flow rate of the liquid supplied from the pump 31 to the cylinder 21. The flow rate of the liquid supplied from the pump 31 to the cylinder 21 changes according to the current flowing through the first solenoid 46 and the second solenoid 47 of the control valve 40.

  In the moving operation, the valve control unit 51 that operates the control valve 40 maintains the current flowing through the first solenoid 46 and the second solenoid 47 at the set current. When the current flowing through the first solenoid 46 and the second solenoid 47 is kept constant, the position of the valve body 41 is kept constant. As a result, the flow rate of the liquid supplied from the pump 31 to the cylinder 21 is kept constant, and the piston 23 moves at a constant speed (set speed).

  In the reversing operation, the valve control unit 51 adjusts the current flowing through the first solenoid 46 and the second solenoid of the control valve 40 so that the piston 23 is decelerated, stopped, and accelerated in order. The operation of the valve control unit 51 will be described with reference to FIG. FIG. 4 is a graph showing the operation of the hydraulic device when the knob 53 of the potentiometer 52 is set to point A. The vertical axis shows the current flowing through the first solenoid 46 and the second solenoid 47, and the horizontal axis Indicates the passage of time. In FIG. 4, the inversion time of the piston 23 is indicated by L1, and the bias current is indicated by Ab1.

  First, in the first reversing operation for reversing the moving direction of the piston 23 from right to left, the valve control unit 51 reduces the current flowing through the first solenoid 46 from the set current Ac. When the current flowing through the first solenoid 46 becomes smaller than the bias current Ab1, the current flowing through the first solenoid 46 is reduced to zero, and at the same time energization of the second solenoid 47 is started. Increase to Ac.

  That is, in the example of FIG. 4, the valve control unit 51 maintains the current flowing through the first solenoid 46 at the set current Ac from time t3 to time t4. Thereafter, the valve control unit 51 gradually decreases the current flowing through the first solenoid 46 from time t4 to time t5 until the current becomes smaller than the bias current Ab1 from the set current Ac. For this reason, from time t4 to time t5, the flow rate of the liquid supplied from the pump 31 to the first space 27 of the cylinder 21 gradually decreases, and the piston 23 decelerates. At time t5, the liquid supply from the pump 31 to the cylinder 21 is stopped, and the piston 23 is stopped. Note that the control valve 40 is in the forward movement state until the time t4 and from the time t4 to the time t5, and the control valve 40 is in the switching state at the time t5.

  Further, the valve control unit 51 starts energizing the second solenoid 47 at time t5, and gradually increases the current flowing through the second solenoid 47 from the value smaller than the bias current Ab1 to the set current Ac from time t5 to time t6. Let After time t6, the valve control unit 51 maintains the current flowing through the second solenoid 47 at the set current Ac. For this reason, from time t5 to time t6, the flow rate of the liquid supplied from the pump 31 to the second space 28 of the cylinder 21 gradually increases, and the piston 23 accelerates. At time t6, the moving speed of the piston 23 in the left direction reaches the set speed. In addition, the control valve 40 which was in the switching state at the time t5 is in the backward movement state after the time t5.

  Next, in the second reversing operation for reversing the moving direction of the piston 23 from left to right, the valve control unit 51 decreases the current flowing through the second solenoid 47 from the set current Ac. When the current flowing through the second solenoid 47 becomes smaller than the bias current Ab1, the current to the second solenoid 47 is reduced to zero and at the same time energization to the first solenoid 46 is started, and then the current flowing through the first solenoid 46 is set to the set current. Increase to Ac.

  That is, in the example of FIG. 4, the valve control unit 51 keeps the current flowing through the second solenoid 47 at the set current Ac until time t1. Thereafter, the valve control unit 51 gradually decreases the current flowing through the second solenoid 47 from time t1 to time t2 until the current becomes smaller than the bias current Ab1 from the set current Ac. For this reason, between time t1 and time t2, the flow rate of the liquid supplied from the pump 31 to the second space 28 of the cylinder 21 gradually decreases, and the piston 23 decelerates. At time t2, the supply of liquid from the pump 31 to the cylinder 21 is stopped, and the piston 23 is stopped. Until time t2, the control valve 40 is in the backward movement state, and at time t2, the control valve 40 is in the switching state.

  Further, the valve control unit 51 starts energizing the first solenoid 46 at time t2, and gradually increases the current flowing through the first solenoid 46 from time t2 to time t3 from a value smaller than the bias current Ab1 to the set current Ac. Let After time t3, the valve control unit 51 maintains the current flowing through the first solenoid 46 at the set current Ac. For this reason, from time t2 to time t3, the flow rate of the liquid supplied from the pump 31 to the first space 27 of the cylinder 21 gradually increases, and the piston 23 is accelerated. At time t3, the moving speed of the piston 23 in the right direction reaches the set speed. Note that the control valve 40 that was in the switching state at time t2 is in the forward movement state from time t2 to time t5.

  By the operation of the hydraulic device 20 described above, the workpiece 14 moves forward at a predetermined speed, then reverses for a predetermined reversal time, and starts returning at the predetermined speed.

  The case where the knob 53 of the potentiometer 52 is fixed at the point A has been described above, but the knob 53 may be fixed at the B point. At this time, the command signal to the control valve 40 differs from the case where it is fixed at the point A only in that the time L2 = 5 and the bias current Ab2 = 5 required for the reversal of the piston 23 are set. That is, with respect to the reversing time of the piston 23, the reversing time L1 in which the knob 53 is fixed at the point A is longer than the reversing time L2 in which the knob 53 is fixed at the point B. Regarding the bias current, the bias current Ab1 in which the knob 53 is fixed at the point A is lower than the bias current Ab2 in which the knob 53 is fixed at the point B. By rotating the knob 53 from the point A to the point B, the bias current value and the predetermined inversion time are controlled to be linked. Further, the bias current value and the predetermined inversion time are controlled simultaneously. By fixing the knob 53 to the point A, the reverse shock of the cylinder 21 can be reduced as will be described later. On the other hand, by fixing the knob 53 to the point B, the cylinder 21 can be reversed in a short time as will be described later.

  The operation of the hydraulic device 20 when the knob 53 is fixed at the point B is shown in FIG. FIG. 5 is a graph showing the operation of the hydraulic device, in which the vertical axis shows the current flowing through the first solenoid 46 and the second solenoid 47, and the horizontal axis shows the passage of time. In FIG. 5, the inversion time of the piston 23 is indicated by L2, and the bias current is indicated by Ab2. In addition, since the operation of the hydraulic device 20 is the same as when it is fixed at the point A, the description thereof is omitted.

[Features of this embodiment]
The hydraulic device 20 of this embodiment has the following features.

  In the hydraulic device 20 of the present embodiment, when the current value of the first solenoid 46 and the current value of the second solenoid 47 become smaller than the bias current, that is, without reducing the current value to zero, the control valve 40 is switched. The cylinder 21 is reversed. Thereby, the speed gradient of the cylinder 21 can be reduced, and the shock caused by the reversing operation of the cylinder 21 can be suppressed.

  In the switching state of the control valve 40 according to the present invention, the supply port 44 is shut off and the first port 42, the second port 43, and the discharge port 45 are communicated. Here, it is assumed that an all-port closed control valve that closes the first port 42, the second port 43, the supply port 44, and the discharge port 45 is employed in the switching state. At this time, when the control valve is switched from the forward movement state to the switching state, the second port 43 that discharges the liquid from the second space 28 of the cylinder 21 is closed, and the inertial force of the cylinder 21 causes the second space 28 and The second pipe 59 connecting the second port 43 becomes high pressure, causing the cylinder 21 to stop suddenly. At the same time, the first port 42 supplying the liquid to the first space 27 is closed, and the second piping 59 connecting the first space 27 and the first port 42 is evacuated by the inertial force of the cylinder 21. This also promotes a sudden stop of the cylinder 21.

  Therefore, when the control valve 40 of the present invention is used, when the control valve 40 is switched from the forward movement state to the switching state, the second port 43 and the discharge port 45 communicate with each other. Accordingly, since the liquid in the second space 28 is discharged through the second port 43, the second pipe 59 connecting the second space 28 and the second port 43 does not become high pressure, and the cylinder 21 stops suddenly. Thus, the cylinder 21 can be smoothly reversed. At the same time, since the first port 42 and the discharge port 45 communicate with each other, the liquid can be supplied to the first space 27 via the first port 42, and the first pipe 58 connecting the first space 27 and the first port 42. Is prevented from becoming a vacuum, and the cylinder 21 is smoothly reversed. The same applies when the control valve 40 is switched from the backward movement state to the switching state. Therefore, the shock caused by the reversing operation of the piston 23 can be suppressed.

  For this reason, even if the current value of the first solenoid 46 and the bias current of the second solenoid 47 during the reversing operation of the cylinder 21 are increased, the shock caused by the reversing operation of the cylinder 21 can be suppressed.

  In the hydraulic device 20 of the present embodiment, the bias current and the predetermined inversion time are controlled so as to be linked. In the hydraulic device 20, the adjustment at the time of reversing the cylinder 21 is usually desired to reduce the reversal shock or to be reversed in a short time, and it is desired that the adjustment between the two can be freely performed.

  In order to reduce the reversal shock, as shown in FIG. 4, the reversing time is lengthened and the cylinder 21 is decelerated to a low speed and then reversed. This is achieved by increasing the inversion time and reducing the bias current.

In order to invert in a short time, it is conceivable to shorten the inversion time. However, if the bias current is small, the speed gradient increases and the shock increases. In order to prevent this, if the bias current is increased, the speed gradient is reduced and the shock can be suppressed. That is, short-time inversion is achieved by shortening the inversion time and increasing the bias current as shown in FIG.
As described above, when the inversion time and the bias current are linked, adjustment during inversion can be freely performed.

  In the hydraulic device 20 of the present embodiment, the bias current and the predetermined inversion time are controlled simultaneously, so that the user can easily adjust the operation at the inversion of the cylinder 21 only by changing the angle of the potentiometer 52.

  As mentioned above, although embodiment of this invention was described based on drawing, it should be thought that a specific structure is not limited to these embodiment. The scope of the present invention is shown not only by the above description of the embodiments but also by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  If the supply port 44 is shut off and the first port 42, the second port 43, and the discharge port 45 are communicated when the control valve 40 is in the switching state, the specific shape is not particularly limited.

  The specific values of the bias current and the inversion time of the piston are not particularly limited as long as the piston 23 is inverted while suppressing the impact. However, the present invention does not include the case where the bias current is zero.

  As long as the potentiometer 52 controls the bias current and the inversion time of the piston in conjunction with each other, various meters, switches, and software parameters can be adopted.

12 Workpiece (member)
21 cylinder 27 first space 28 second space 31 pump 40 control valve 42 first port 43 second port 44 supply port 45 discharge port

Claims (3)

A cylinder for reciprocating a member;
A pump for supplying liquid to the cylinder;
A control valve disposed between the cylinder and the pump;
The cylinder has a first space to which liquid is supplied when the member is moved forward, and a second space to which liquid is supplied when the member is moved backward,
The control valve is
A first port in communication with the first space, a second port in communication with the second space, a supply port to which liquid is supplied from the pump, and a discharge port for discharging the liquid,
When the current value of the first solenoid is equal to or greater than a predetermined value, the forward movement state of communicating the supply port and the first port and communicating the second port and the discharge port;
When the current value of the second solenoid is equal to or greater than a predetermined value, a return state in which the supply port communicates with the second port and the first port communicates with the discharge port;
A switching state in which when the current value of the first solenoid and the current value of the second solenoid are smaller than a predetermined value, the supply port is shut off and the first port, the second port, and the discharge port are communicated with each other; A hydraulic device characterized in that The member moves forward at a predetermined speed, then reverses with a predetermined reversal time, and starts returning at a predetermined speed,
The hydraulic apparatus according to claim 1, wherein the predetermined value and a predetermined inversion time are controlled so as to be interlocked with each other.   The hydraulic apparatus according to claim 2, wherein the predetermined value and a predetermined inversion time are controlled simultaneously.

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