JP2002000026U - Fluid pressure device - Google Patents

Abstract

(57) [Summary] [Object] To provide a fluid pressure device capable of achieving high speed by reducing waste of power consumption during a cycle operation of a punching press. A fluid pressure device for a punching press,
A first fluid discharge means which can be controlled at least to high and low pressures, and a second fluid discharge means which is controlled to a discharge pressure substantially equal to the low pressure side pressure during operation; The connection between the pressurized fluid supply flow path and the discharge ports of the first and second fluid discharge means is selectively communicated and cut off at an opening corresponding to an electric signal.
And the discharge amount of either one of the second fluid discharge means or the sum of both discharge amounts is selectively supplied to the fluid pressure actuator. Further, the discharge pressure of the fluid discharge means is detected as an electric signal, and based on the detected signal, the control is electrically performed so as to increase or decrease the rotation speed of the drive motor of the fluid discharge means in accordance with the hit rate of the punching press.

Description

[Detailed description of the invention]

[0001]

[Industrial applications]

 The present invention relates to a hydraulic device for a punching press for driving a ram of the punching press by a hydraulic actuator.In particular, the ram is operated at a constant stroke, and a high load load is applied to a part of the operation stroke. The present invention relates to a fluid pressure device for a punching press in which energy consumption is reduced as much as possible.

[0002]

[Prior art]

 In punching presses, one of the press workings, there is a method in which the press ram is driven by a hydraulic actuator such as a hydraulic cylinder instead of a mechanical drive system such as a flywheel. It is known that there is an advantage that unnecessary impact and noise in each press cycle can be prevented.

In such a fluid pressure device for driving an actuator in a fluid pressure drive type punching press which has been put into practical use, a fluid pressure supply source such as a pump is changed according to a maximum load in a machining operation cycle. Actuated by controlling the discharge fluid from the fluid pressure supply source while switching multiple control valves by switching valves linked to the press drilling operation. The eta is cycled according to a desired operation pattern.

[0004]

[Problems to be solved by the invention]

 In this way, when the press processing cycle operation of the same pattern is repeated like drilling with a punching press, the press tool gives plastic deformation to the work during the period when the applied load increases during one cycle operation. This is until the work breaks.

[0005] In a conventional hydraulic device used for driving an actuator in such a hydraulic drive type punching press, a pump as a fluid pressure supply source is driven at the same pressure setting during a cycle period. As it continues, high-pressure driving is always performed regardless of the size of the load, and when the load is small, excessive energy is consumed and the pump drive power is wasted, and the cooler device for cooling the heat generated by the working fluid also becomes large. Various disadvantages have been pointed out.

[0006] Accordingly, if the cycle operation of the punching press is to be further accelerated using this type of conventional fluid pressure device, the power consumption is wasted with the increase in the pump capacity of the fluid pressure supply source. It will be huge. In order to maintain the pressure by accumulating pressure in the accumulator in the circuit even when the actuator is not driven, a variable displacement pump is used as the fluid pressure supply source. The driving power consumption of the variable displacement pump for maintaining the pressure is not negligible.

[0007] The present invention is intended to solve such a problem, and has as its main object to provide a fluid pressure device for a punching press that can reduce waste of power consumption. It is another object of the present invention to provide a fluid pressure device for a punching press that can reduce waste of power consumption and speed up cycle operation.

[0008]

[Means for Solving the Problems]

 In the fluid pressure device of the present invention, the pressurized fluid supplied from the fluid discharge means is controlled by a plurality of switching valves, and the ram of the punching press is driven by a fluid pressure actuator. At least one or more first type fluid discharge means (1) whose discharge pressure can be controlled to at least two kinds of pressures, a first pressure on a high pressure side and a second pressure on a relatively low pressure side; The inside is at least one or more of a second type of fluid discharge means (2) controlled to a discharge pressure approximately equal to the second pressure on the relatively low pressure side, and an additional pressure reaching the fluid pressure actuator (3). The connection between the pressurized fluid supply flow path (5) and each of the discharge ports of the plurality of fluid discharge means including the first and second types of fluid discharge means (1, 2) is selected by an opening according to an electric signal. Communication And the switching function to supply the fluid discharged from each of the fluid discharge means in an appropriate combination and supply the resultant to the fluid pressure actuator (3), and only one of the fluid discharge means. Control valve means (7) having a switching function of supplying the discharged fluid to the pressurized fluid supply flow path (5).

In a preferred aspect of the present invention, there is further provided a flow control means (23, 24) for controlling the discharge flow rate from the fluid discharge means (2) of the second type to at least two large and small flow rates.

[0010] In another aspect of the present invention, the first type of fluid discharge means (1) includes pressure control means (13, 14, 14a, 15, 15a) for switching the discharge pressure in stages. In another aspect, a pressure control means (13a) for continuously changing the discharge pressure is provided.

In still another aspect of the present invention, a ram of a punching press is driven by a hydraulic actuator by controlling a pressurized fluid supplied from a fluid discharging means by a plurality of switching valves. In the fluid pressure device, an electric motor for driving the fluid discharge means, a pressure sensor means for detecting a discharge pressure of the fluid discharge means and outputting an electric signal, and a hitting rate of a punching press based on the electric signal. When the discharge pressure that changes accordingly becomes equal to or lower than a predetermined lower limit pressure, the rotation speed of the electric motor is changed to a speed increase side, and when the discharge pressure changes to a predetermined upper limit pressure or more, the rotation speed of the electric motor is set to a deceleration side. Electrical control means for controlling the number of revolutions of the electric motor so as to be changed.

[0012]

[Action]

 In the fluid pressure device of the present invention, the fluid pressure actuator is driven by at least a two-pressure system of a high pressure and a low pressure. When the load is low, the second fluid discharge means is used as a low-pressure fluid supply source. At this time, in order to reduce the capacity of the low-pressure fluid supply source, the first type of fluid discharge means is of a variable discharge pressure control type, and at low load, the first type of fluid discharge means is changed to a low pressure setting. The discharge flow rate is added to the discharge flow rate of the low-pressure fluid supply source (the second type of fluid discharge means) and supplied to the actuator, thereby reducing unnecessary energy consumption. A plurality of these first and second fluid discharge means may be provided, respectively, and their discharge pressure and total flow rate are appropriately combined depending on the load capacity.

In the case of performing a punching press by a punching press, the cycle pattern of the press operation is a first operation mode in which a ram has a medium speed and low load lowering period, a low speed and a high load lowering period, and a medium speed low load. In the case of a unit cycle including a rising period in order, the switching function of the control valve means is selected during the middle and low load falling periods and the middle and low load rising periods before and after, and the actuator is switched from the second type of fluid discharging means to the actuator. Supply only discharge fluid. In this case, the fluid discharge means of the second type consumes predetermined power according to the set pressure and the set flow rate, and the actuator operates at a force and a speed corresponding to the pressure and the flow rate. On the other hand, the first fluid discharge means can be operated, for example, in a high pressure operation state, and the discharged fluid can be stored in, for example, an accumulator for later use.

In the intermediate low-speed / high-load descent period, only the discharge fluid from the first fluid discharge means is supplied to the actuator by selecting the switching function of the control valve means. Thereby, the high pressure and low flow rate fluid is supplied to the actuator from the first fluid discharge means under the flow control by the control opening of the control valve means, and the actuator is provided with the corresponding strong force and low speed. Will work. In this case, the discharge fluid from the second type of fluid discharge means can be stored in another accumulator and reused, for example, as described above.

In any case, the power consumption during the cycle in this first mode of operation corresponds to the total power consumption of the first and second types of fluid discharge means, for example, the first type of fluid discharge means. Since the power is lower than that when running through with the high pressure set, the power reduction effect is clear.

In the fluid pressure device of the present invention, it is possible to perform a cycle operation even faster than the above operation mode. That is, the first fluid discharging means is set to a low pressure operation state, the set pressure is set to be approximately equal to that of the second fluid discharging means, and the switching function of the control valve means is switched to switch the first and second fluid discharging means. When the ejected fluids are merged and the merged fluid is supplied to the actuator from the same supply channel, the actuator operates at a high speed at the combined flow rate.

When the first type of fluid discharge means is operated at a low pressure setting, the power is considerably lower than at the high pressure setting, and in this case, the total power with the power of the second type of fluid discharge means The amount can still be suppressed within a range lower than the high pressure set operating power of the first type of fluid discharge means. This means that there is a margin of electric power as compared with the first operation mode. Therefore, this is used to increase the set flow rate of the second type of fluid discharge means as shown in the embodiment described later. If so, the actuator can be operated at a higher speed, which is the function of the flow control means in the invention according to the second aspect.

The fluid pressure device according to the third aspect of the present invention includes pressure control means for switching the discharge pressure of the first type of fluid discharge means in a stepwise manner. When a variable displacement pump is used as the first fluid discharge means, the pressure control means comprises a pressure control valve having a different set pressure for controlling the pilot pressure of the pressure compensator control and a solenoid valve for selecting the same. can do. Therefore, in this case, the discharge pressure of the first type of fluid discharge means can be switched stepwise into a plurality of stages, such as high, low, or three pressures.

The fluid pressure device according to the fourth aspect of the present invention is provided with a pressure control means for continuously changing the discharge pressure of the first type of fluid discharge means. This pressure control means can be realized by a method in which, for example, when a variable displacement pump is used as the first fluid discharging means, the pilot pressure of the pressure compensator control is proportionally controlled in accordance with an electric signal by a proportional electromagnetic pressure control valve. It is. Therefore, in this case, the discharge pressure of the first type of fluid discharge means can be steplessly controlled to a desired set pressure.

In the present invention, the first and second types of fluid discharge means can be constituted by a variable displacement pump driven by an induction motor, or a constant discharge pump is driven by a torque servo motor or a synchronous motor. What is done can also be used. In the latter case, the efficiency at low load is improved compared to the former, so the energy consumption can be further reduced, and when the actuator is not driven, the minimum use of the pump is sufficient to maintain the required circuit pressure. By constructing a control circuit so as to reduce the motor speed to the allowable speed, wasteful energy consumption can be further reduced.

Also, as in a press machine, the load pressure changes due to a change in the hit rate of the ram or the driving / stopping of the actuator. However, in such a case, for example, the pressure fluctuation is adjusted to fall within a necessary and sufficient range. If the load pressure falls below a desired level, the motor speed is controlled in accordance with the load pressure, such as by increasing the motor speed, so that the minimum pressure required for the fluid circuit is maintained and unnecessary pressure rise is avoided. In this way, energy consumption can be reduced.

For this reason, in the fluid pressure device according to the present invention, the discharge pressure of the fluid discharge means is detected by the pressure sensor means, and the electric control is performed based on the electric signal from the pressure sensor means. Means for controlling the rotation speed of the drive motor of the fluid discharge means, and when the discharge pressure of the fluid discharge means, which changes according to the hit rate of the punching press, becomes equal to or lower than a predetermined lower limit pressure, the electric motor is driven. The rotation speed is changed to a speed increase side, and when the pressure becomes equal to or higher than a predetermined upper limit pressure, the rotation speed of the electric motor is changed to a reduction speed side. When there are a plurality of fluid discharge means, for example, when the discharge pressure of each fluid discharge means is detected by a separate pressure sensor means and the discharge pressure of one of the fluid discharge means is out of the set pressure range, The rotation speed of the motor can be controlled so as to compensate for this, or the discharge pressure of one specific fluid discharge means is monitored by pressure sensor means according to the specifications such as the operating conditions of the device to control the rotation speed of the motor. It is also possible to do so.

In the present invention, the control valve means can be constituted by, for example, a servo valve of a hydraulic pilot control system. However, when the consumption of the pilot flow as internal leakage is a problem, an electric motor (rotary type) of a position servo control system is required. By using a servo-motor-driven valve that moves the valve body using a linear type, the pump discharge amount corresponding to the internal leakage flow rate becomes unnecessary, and it is possible to further reduce energy consumption. Also, since such a servo motor driven valve can drive the valve at a higher speed than a servo valve of the hydraulic pilot control type, it is necessary to design a relatively large overlap of the control orifice of the main valve. This can also reduce internal leakage in the control valve means.

Further, in the present invention, the switching timing of the discharge pressure of the first type of fluid discharge means and the switching timing of each control valve including the control valve means are controlled in accordance with the operation of a punching press. In order to achieve this, it is also possible to combine an appropriate sensor for detecting the position of the ram and the load pressure by the actuator with the fluid pressure device of the present invention, and to appropriately automatically control the switching timing by a detection signal from these sensors.

Hereinafter, a hydraulic device for a punching press according to the present invention will be described with an embodiment.

[0026]

【Example】

 FIG. 1 is a hydraulic circuit diagram showing a configuration of an actuator drive system of a punching press device including a fluid pressure device according to an embodiment of the present invention, and constitutes a first type of fluid discharge device as a fluid discharge device. The apparatus includes a variable displacement pump 1 and a variable displacement pump 2 constituting a second type of fluid discharge means.

A hydraulic cylinder 3 as an actuator for driving the ram of the punching press is operated by pressure oil supplied from these variable displacement pumps 1 and 2 via a pressure oil supply channel 5, 5 is provided with an electric / hydraulic servo valve 4 for controlling the elevation of the cylinder 3. The servo valve 4 switches and connects the hydraulic oil supply flow path 5 and the return flow path 6 to each of the cylinder chambers on the head side and the rod side of the hydraulic cylinder 3, and variably controls the connection opening in accordance with an electric signal input. It is possible.

Another electric / hydraulic servo valve 7 as control valve means is connected between the discharge port of the first variable displacement pump 1 and the supply flow path 5. Further, the return flow path 6 is dropped to a tank line, and a volume device 31 for absorbing an oil hammer is connected on the way.

The pump main body 10 of the first variable displacement pump 1 and the pump main body 20 of the second variable displacement pump 2 have their rotating shafts connected so as to be commonly driven by the same electric motor 9. The number of rotations of the electric motor 9 is controlled by a motor drive control device 42 which receives a control command signal from a computer 40, and the computer 40 adjusts the discharge pressures of both pumps detected by the pressure sensors p1 and p2 from the discharge lines of both pumps. Based on this, a control command for controlling the rotation speed is given to the drive control unit 42 so that the discharge pressure of each of these pumps falls within a preset minimum-maximum pressure range.

In the first variable displacement pump 1, the compensator valve 12 that controls the discharge amount variable element 11 under its own pressure is either a relief valve 13 for setting the spring chamber side pressure to a high pressure or a relief valve 14 for setting a low pressure. In this example, the solenoid valve 15 is interposed between the low-pressure setting relief valve 14 and the tank. When the state is switched from the setting and illustrated state, the high pressure setting is set. Setting the high and low two pressure, for example in this embodiment a high-pressure setting relief 13 P _H, the low-pressure setting relief P _{L (<P H),} and this first set discharge flow rate of the variable displacement pump 1 is Q _A.

The pressure control of the first variable displacement pump itself is pressure compensation control by self-pressure of a well-known high / low pressure switching system using a solenoid valve. For example, in state of the solenoid valve 15 is shown, the set pressure of the compensator valve 12 is a pressure P _L is set to a low pressure setting relief valve 14, to the discharge pressure of the pump main body 10 reaches the P _L is the compensator valve since 12 is communicated to the pressure chamber of the variable discharge element 11 of the pump main body 10 to Tan Klein, variable element 11 discharge in displacement of by the pump main body 10 is set discharge amount Q _a to the position which gives the set ejection amount And thereby act to increase the load line pressure.

The discharge pressure of the pump main body 10 is opened relief valve 14 reaches the P _L, passes through the discharge pressure oil throttle 16 flows into the tank through the solenoid valve 15 from the relief valve 14, the flow generator The compensator valve 12 switches to the function on the left side in the figure due to the differential pressure across the throttle 16 caused by the pressure, and the discharge pressure of the pump main body 10 is introduced into the pressure chamber of the variable element 11 via the compensator valve 12. And whereby the variable element 11 must be biased to cut-off position so as to minimize pump discharge amount of such discharge amount internal leakage is reduced to approximately zero, the pressure in the load line is set pressure P _L or more It works to keep things from happening.

[0033] In a low-pressure setting state of the above, another high pressure setting relief valve 13 remains closed because never discharge pressure reaches the set pressure P _H, when switching the solenoid valve 15 from the state shown in the figure Since the low pressure setting relief valve 14 is shut off from the tank line, the high pressure setting relief valve 13 controls the set pressure of the compensator valve 12 at this time. Thus the above-described operation is performed in the same manner the pressure P _H which is set to a high-pressure setting relief valve 13 as the cutoff pressure, the variables 11 pump main 10 until the pressure in the load line reaches the set pressure P _H together operate at set discharge amount Q _a, it operates such that the pressure in the substantially zero discharge amount and the discharge pressure reaches the set pressure P _H load line kept to be the set pressure P _H or more.

The second variable displacement pump 2 is of a two-displacement control type which is a modification of the well-known two-pressure two-displacement control method using an electromagnetic valve in this embodiment. In other words, so as to control the compensator valve 22 to set the low-pressure setting relief valve 26 and the high-pressure setting relief valve 25 to set the pressure P _L substantially the same pressure in a general two-pressure dual capacity control method, an electromagnetic valve A throttle valve 24 whose opening degree is switched by 23 is inserted in the discharge line.

The compensator valve 22 that controls the discharge amount variable element 21 by its own pressure receives the outlet pressure of the throttle valve 24 on its spring chamber side and receives the inlet pressure of the throttle valve 24 on the side facing the spring chamber. , Under the action of the differential pressure across the throttle valve 24. The relief valves 26 and 25 receive the outlet pressure of the throttle valve 24, and the solenoid valve 23 selectively connects the outlet of the relief valve 26 to the tank line by an electric signal or acts on the side of the throttle valve 24 facing the spring. .

In the state shown in the figure, the solenoid valve 23 drops the outlet of the relief valve 26 to the tank line. In this state, the throttle valve 24 is opened at the full opening by its spring force, and the solenoid valve is opened by the electric signal. When the switch 23 is switched, the throttle valve 24 switches to a certain throttle opening. This discharge flow rate from the second variable displacement pump 2 can be switched to the _{Q B} and _{Q C (however, Q A <Q B <Q} C).

[0037] When the solenoid valve 23 is in the illustrated state, the discharge amount variable element of the throttle valve compensator valve 22 to the outlet pressure of 24 reaches the pressure P _L which is set in the relief valve 25 and 26 pump mainly 20 since the pressure chamber 21 is communicated to the tank line, the amount required to variables 21 is displaced to the set ejection amount position, thus the discharge flow rate Q _{C +} α (α is from the pump main 20 compensate for internal leakage amount ) Pressure oil is discharged. The pressure oil passes through the throttle valve 24 fully opened state set flow rate Q _C Ru sent to the load side.

[0038] When the outlet pressure of the throttle valve 24 reaches the set pressure P _L, through the relief valve 25, 26 to Tan Klein reducing the pressure of the spring chamber side of the compensator valve 22, the pump main body on the other side This ensures The compensator valve 22 receiving the action of the discharge pressure 20 switches from the state shown in the figure to guide the discharge pressure to the pressure chamber of the variable element 21. As a result, the pump main body 20 is in a cutoff state and the discharge amount is changed. To almost zero. This is no different from the pressure control of a variable pump using the normal load pressure detection method.

When the solenoid valve 23 is switched from the state shown in the figure, the outlet of the relief valve 26 is cut off from the tank line, so that the relief valve 26 does not contribute to the pressure control of the pump main body 20. played by the set pressure P _L as previously described by the relief valve 25. Relief valve 26 in this case, when the outlet pressure of the throttle valve 24 is prevented from acting on the discharge pressure throttle valve 24 until it reaches the set pressure P _L, the outlet pressure reaches the set pressure P _L The discharge pressure is applied to the throttle valve 24 to switch the opening from the full opening to the throttle opening.

Thus, the flow rate supplied from the second variable displacement pump 2 to the load is Q_B (Q_B <Q_C ). In the pump main body 20, the discharge amount is Q_B Setting discharge amount Q_C The rise of the discharge pressure according to the difference between the pressure and the pressure increases, but this acts on the compensator valve 22 as a pressure difference before and after the throttle valve 24, so that a corresponding pressure is generated in the pressure chamber of the variable element 21, The variable element 21 is displaced in the direction to decrease the discharge amount by that amount, and the discharge amount from the pump body 20 correspondingly decreases, and the flow rate Q _B Equilibrate to + α.

The electric / hydraulic servo valve 7 as control valve means has switching functions a, b, and c. In the functions a, b, and c, the opening degree can be set according to the input electric signal. In the switching function a, the discharge pressure oils of both the variable displacement pumps 1 and 2 are summed and can be supplied to the pressure oil supply flow path 5, and in the switching function b (neutral position), the discharge from the second variable displacement pump 2 is performed. Only the pressure oil can be supplied to the pressure oil supply flow path 5, and only the discharge pressure oil from the first variable displacement pump 1 can be supplied to the pressure oil supply flow path 5 in the switching function c.

In this embodiment, an accumulator 34 is provided in the pilot line of the two servo valves 4 and 7, and a part of the discharge pressure oil from the second variable displacement pump 2 Although it is introduced as oil, the pilot pressure oil may be introduced from the discharge pressure oil of the first variable displacement pump 1. When the discharge force fluctuates greatly, for example, 2: 1 due to the operation sequence, a pressure adjustment hydraulic circuit that switches the adjustment pressure in synchronization with the switching of the solenoid valve 15 is used to stabilize the pilot pressure. It is preferable to add to the pilot system.

In FIG. 1, 35 is an accumulator for accumulating the discharge pressure of the first variable displacement pump 1, 36 is an accumulator for accumulating the discharge pressure of the second variable displacement pump 2, and 37 is an accumulator 35. This is a solenoid valve for selectively accumulating pressure. Numeral 38 denotes an electromagnetic valve which is opened in the state shown in the drawing when the pressure of both discharge lines including both accumulators 35 and 36 is released to the tank.

The computer 40 controls the number of revolutions of the electric motor 9 within a set range via the drive control device 42 based on the detection signals of the pressure sensors p 1 and p 2, and also detects the rotation speed of the motor 9 with another pressure sensor p 3. The switching operation between the servo valves 4 and 7 and the solenoid valves 15, 23, 37 and 38 is given in advance based on the change in the pressure on the head side of the hydraulic cylinder 3 (or the position of the ram). It is also used to control according to a sequence. The control of the operation sequence is not limited to the method of detecting the pressure by the pressure sensor p3 and the detection of the ram position. For example, a press machine or the like performs a trial press of the work and notifies the computer 40 of the operation switching timing. A so-called teaching method may be adopted in which teaching is performed and the operation of each valve and motor is switched at the teaching timing without waiting for a change in the detection pressure of the pressure sensor p3.

The operation of the fluid pressure device having the hydraulic circuit configuration of FIG. 1 according to the present embodiment, that is, the hydraulic device for driving an actuator for punching press is described in the first operation mode of FIG. 2 and the second operation mode of FIG. This will be described below.

First, in the first operation mode shown in FIG. 2, the entire operation sequence is controlled by the computer 40 based on, for example, the detection pressures of the pressure sensors p1 to p3 and a work position detection switch (not shown). The time-dependent movement of the ram by the hydraulic cylinder 3 is as follows: the start time t0 to t1 is a medium speed low load descent period, and the t1 to t2 is a low speed high load for giving deformation and breakage to the work with low impact and low noise. During the descending and descending period, the period from t2 to t3 is the middle speed low load descending period corresponding to the penetration after the punching of the workpiece is completed, the period is reversed at t3 and the middle speed low load increasing period is to return to t4, and thereafter t5. Up to the axis movement period, when the workpiece is relatively thick or the machining area is large. In this case, operate both pumps 1 and 2 over the entire period from t0 to t5, the pump 1 has a high pressure set constant P _H is switched from the state shown the solenoid valve 15, also the pump 2 keep a low flow rate setting Q _B by switching the solenoid valve 23 from the illustrated state.

On the other hand, with respect to the pressure oil supplied to the cylinder 3, at time t0, the servo valve 4 for raising and lowering control is set to the function a, and the servo valve 7 is set to the neutral function b over the period from t0 to t1. Discharge pressure oil (P _L , Q _B ) from the pump 2 is supplied to the head side of the cylinder 3. Next, at time t1, the servo valve 7 is set to function c, and pressurized oil (P _H , Q _A ) from the pump 1 which is in the high pressure setting state until time t2 is supplied to the head side of the cylinder 3. Period from subsequent time t2 to t 3 is supplied again discharged pressurized fluid (P _{L, Q B)} of the pump 2 is returned to the servo valve 7 to the neutral function b of the head side of the cylinder 3.

At time t 3, the servo valve 4 for elevation control is switched to the function c, and during the period from t 3 to t 4, the servo valve 7 is maintained at the neutral function b as in the immediately preceding period, and the pressure oil from the pump 2 ( P _L , Q _B ) is supplied to the rod side of the cylinder 3. At this time, since the pressure receiving area of the rod side of the cylinder 3 is smaller by the cross-sectional area of the piston rod than that of the head side, compared to the medium speed low load lowering period of t0 to t1 when the cylinder operates by the pressurized oil inflow from the same pump 2 The ram will rise at a faster speed.

During the period from t4 to t5, the elevation control servo valve 4 is returned to the neutral function b, the cylinder 3 is shut off from the pressure oil supply source, and the cylinder 3 is moved on the horizontal axis by another moving system.

Here, the pressurized oil from the pump 1 is accumulated in the accumulator 35 during the period of t0 to t1 and the period of t2 to t5, and the pressure of the pump 2 is increased during the period of t1 to t2 and the period of t4 to t5. Is accumulated in the accumulator 36, and the accumulated pressure oil is used when a subsequent cycle operation is required.

In the above-described first operation mode, only the pressure oil from the pump 2 is supplied to the cylinder during the middle-speed low-load rise period from t3 to t4, but it is necessary to further increase this speed. At a certain time, at time t3, the solenoid valve 15 is set to the switching position as shown in FIG. 1, the pump 1 is set to the low pressure, and the servo valve 4 for raising and lowering control is switched to the function c, during the period from t3 to t4. Thus, the servo valve 7 may be maintained at the function a, and the pressure oil from the pump 1 and the pressure oil from the pump 2 may be summed and supplied to the rod side of the cylinder 3. Further, in this case, if the solenoid valve 23 is switched in synchronization with the switching position as shown in FIG. Of course, such high-speed driving of the cylinder 3 by the combined flow rate can be similarly performed during the low load falling period from t0 to t1.

The discharge pressures of the pumps 1 and 2 are monitored by the pressure sensors p1 and p2, and the computer 40 operates as long as the discharge pressures of these pumps fall between the upper limit pressure and the lower limit pressure stored in advance. A control command is given to the control device 42 to rotate the electric motor 9 at the set number of revolutions. As the hit rate of the press increases, the discharge pressure of the pumps 1 and / or 2 decreases because the hydraulic cylinder 3 requires a correspondingly large flow rate. In this case, the above-described pressure compensation by the compensator valves 12 and 22 is performed. There is a case where the compensation operation cannot compensate. For this reason, the computer 40 monitors the pressures detected by the pressure sensors p1 and p2 and changes the control command to the speed increasing side when these discharge pressures are going to be lower than the lower limit pressure. The rotation speed is increased to increase the discharge amount of the pumps 1 and 2, and the discharge pressure of each pump is restored.

On the other hand, when the hit rate becomes low and the axis movement period becomes long, or when the machining is temporarily stopped, the discharge pressure of the pumps 1 and / or 2 becomes high conversely. When the pressure becomes higher than the upper limit pressure, the computer 40 changes the above-mentioned control command to the deceleration side, whereby the rotation speed of the electric motor 9 itself is reduced and the discharge amounts of the pumps 1 and 2 are reduced. Here, the lower limit pressure is set corresponding to a holding pressure sufficient to generate a force required for processing in the target machine, and the upper limit pressure is set corresponding to an allowable pressure determined by the machine.

Next, the second operation mode shown in FIG. 3 is an example of a high-speed cycle operation suitable for a relatively light load._L , Pump 2 has large flow rate setting Q _C It is operated with. That is, the solenoid valve 15 and the solenoid valve 23 are kept in the illustrated state. All the operation sequences are controlled by the computer 40 based on, for example, detection pressures of the pressure sensors p1 to p3 and a work position detection switch (not shown) as in the above-described example.

The supply of pressurized oil to the cylinder 3 is performed by controlling the servo valve 7 with the function a throughout the entire period, so that the pressurized oil from the pump 1 and the pressurized oil from the pump 2 are added together and introduced into the supply passage 5. and, summing the flow rate of both pumps _{(Q D = Q a + Q} C) in Cylinders 3 to be driven. The period of t0 to t1 in FIG. 3 is a falling period, which is achieved by setting the servo valve 4 for elevation control to function a. The period from t1 to t2 is an ascending period, which is achieved by setting the servo valve 4 for elevation control to function c. The period from t2 to t3 is a horizontal axis movement period of the cylinder 3 in which the servo valve 4 has the neutral function b.

It should be noted that the first and second operation modes given here are representative examples for explanation, and in the present invention, various other operation modes are also set to each solenoid valve and This can be realized by an electric sequence of a servo valve or the like.

In each of the above-described embodiments, it is only necessary that each pump is operated with the minimum discharge amount required for the circuit during the axis movement period. Therefore, the computer 40 uses the detection results of the pressure sensors p1 and p2. Instead of lowering the rotation speed of the motor 9, the signal indicating that the shaft movement is being performed is taken into the computer 40 from within the control system, and the rotation speed of the motor 9 during the shaft movement period is determined according to the required torque. Alternatively, the discharge amount may be reduced so that the power consumption in the electric motor 9 may be further reduced.

In the illustrated embodiment, the electric motor 9 is configured as a common driving motor for both the pumps 1 and 2, but a separate driving motor may be provided for each of the pumps 1 and 2. . Furthermore, by using a synchronous motor instead of the induction motor as the driving motor, it is possible to realize the rotation speed and torque output control according to the load with a relatively simple control circuit.

Further, in the above-described embodiment, the case where both servo valves 4 and 7 are constituted by hydraulic pilot type electric / hydraulic servo valves has been described. However, these servo valves are rotary servo type position servo control type. Alternatively, it may be constituted by a servo motor drive valve for moving the main valve body by a linear type AC motor. In this case, the pilot system having the accumulator 34 in FIG. 1 is unnecessary.

In the embodiment shown in FIG. 1, the discharge pressure of the first variable displacement pump 10 is controlled by the solenoid valve 15 to switch between high and low pressures. As shown in FIG. 4, in addition to the relief valve 13 for setting the high pressure and the relief valve 14 for setting the low pressure, a relief valve 14a for setting the medium pressure and a solenoid valve 15a for selecting the same are provided in parallel. In this case, when the solenoid valve 15 is set to the switching state shown in the figure, the low pressure setting is set, when the solenoid valve 15 is switched from the state shown to the medium pressure, the medium pressure setting is set, and the solenoid valve 15a is also set to the state shown in the figure. When the state is switched from, the high pressure is set. Needless to say, by providing a plurality of similar relief valves and solenoid valves, it is possible to switch the pressure setting to a desired number of stages.

Further, instead of switching the discharge pressure of the first variable displacement pump 10 stepwise by the solenoid valves 15 and 15a, the discharge pressure can be changed steplessly or continuously. As shown in FIG. 5, the relief valve 13 may be constituted by a proportional electromagnetic relief valve 13a, and its control pressure may be continuously controlled to a desired pressure value according to an electric signal. In FIG. 5, the low pressure setting relief valve 14 is inserted into the circuit by the solenoid valve 15 on the assumption that a low pressure is set lower than the pressure control range of the proportional electromagnetic relief valve 13a. If the change in the discharge pressure is within the pressure control range of the proportional electromagnetic relief valve 13a, the relief valve 14 and the electromagnetic valve 15 need not be provided.

In addition, the present invention is not limited to such a punching press apparatus, and may be appropriately changed to a driving fluid pressure device of a fluid pressure actuator for driving a working urging member (tools, etc.) of various forming machines. In addition it can be used.

[0063]

[Effect of the invention]

 As described above, according to the invention as set forth in claims 1 to 4, when a plurality of fluid discharge means constituted by a multiple pump or the like is employed, a part thereof is set to a discharge pressure variable control method. In addition, the control valve means for selectively supplying the total flow rate is combined with this, so that unnecessary power consumption during cycle operation can be reduced. The effect is that an effective fluid pressure device can be provided for the accompanying punching press.

Further, according to the invention of claim 5, when the load pressure changes greatly depending on the operation pattern of the actuator, this pressure fluctuation falls within a necessary and sufficient range according to the hit rate of the punching press. For example, when the load pressure is lower than the desired level, the motor speed is increased, or when the load pressure is higher than the desired level, the motor speed is reduced. By controlling the number, it is possible to maintain the minimum pressure required for the fluid circuit and to avoid an unnecessary rise in pressure, thereby reducing the energy consumption.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing a configuration of an actuator drive system of a punching press device including a fluid pressure device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a cylinder drive pattern in a first operation mode and a pressure oil pattern of each pump and cylinder.

FIG. 3 is an explanatory diagram showing a cylinder drive pattern in a second operation mode and a pressure oil pattern of each pump and cylinder.

FIG. 4 is a hydraulic circuit diagram showing a configuration of a main part according to another embodiment of the present invention.

FIG. 5 is a hydraulic circuit diagram showing a configuration of a main part according to still another embodiment of the present invention.

[Explanation of symbols]

 1: Variable displacement pump (first type fluid discharge means) 2: Variable displacement pump (second type fluid discharge means) 3: Hydraulic cylinder (fluid pressure actuator) 5: Pressurized oil supply flow path (pressurized fluid) 7) Electric / hydraulic servo valve (control valve means) 40: Computer 42: Motor drive control device

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Osamu Kamada 5244-1 Oba, Fujisawa-shi, Kanagawa 14-303 Shonan Shiroyama F-term (reference) 3H089 AA16 AA20 AA35 BB01 CC01 DA02 DA08 DA14 DA18 DB03 DB13 DB33 DB46 DB49 DC02 EE17 EE31 EE36 FF07 GG02 JJ03 4E048 MA09 4E090 AA01 AB01 BA01 CA01 EB01 HA04

Claims (5)

[Utility model registration claims] 1. A hydraulic device for a punching press, wherein a pressurized fluid supplied from a fluid discharge means is controlled by a plurality of switching valves to drive a ram of the punching press by a hydraulic actuator. At least one or more first-type fluid discharge means whose discharge pressure can be controlled to at least two types of pressures, a first pressure and a second pressure on a relatively low pressure side; At least one or more second type fluid discharge means controlled to a discharge pressure approximately equal to the second pressure, a pressurized fluid supply flow path leading to the fluid pressure actuator, and the first and second types of fluid discharge means. The connection with each discharge port of the plurality of fluid discharge means including the fluid discharge means is selectively communicated and blocked with an opening degree according to an electric signal, and the discharge from each of the fluid discharge means is performed. A switching function of adding fluids in an appropriate combination and supplying the fluid pressure actuator to the fluid pressure actuator and a switching function of supplying a discharge fluid from only one of the fluid discharge units to the pressurized fluid supply flow path. And a control valve means. 2. The fluid pressure device according to claim 1, further comprising a flow rate control means for controlling a discharge flow rate of the second type of fluid discharge means to at least two large and small flow rates. 3. A pressure control means for switching a discharge pressure of said first type of fluid discharge means in a stepwise manner.
The fluid pressure device according to claim 1. 4. The fluid pressure device according to claim 1, further comprising a pressure control means for continuously changing a discharge pressure of the first type of fluid discharge means. 5. A fluid pressure device for a punching press in which a pressurized fluid supplied from a fluid discharge means is controlled by a plurality of switching valves to drive a ram of the punching press by a fluid pressure actuator. A driving motor, pressure sensor means for detecting the discharge pressure of the fluid discharge means and outputting an electric signal, and based on the electric signal, the discharge pressure, which varies according to a hit rate of a punching press, is a predetermined pressure. When the pressure is equal to or lower than the lower limit pressure, the rotation speed of the electric motor is changed to a speed increase side, and when the pressure is equal to or higher than a predetermined upper limit pressure, the rotation speed of the motor is changed to a deceleration side so that the rotation speed of the motor is changed. A fluid pressure device comprising: an electrical control unit for controlling the fluid pressure device.