JP6950596B2 - Hydraulic supply system for injection molding machines - Google Patents

Description

The present invention relates to a hydraulic supply system that supplies hydraulic oil to an actuator included in an injection molding machine.

Injection molding includes a mold clamping process that closes a pair of molds, an injection process that injects a molten material into a cavity in the mold, a pressure holding process that keeps applying pressure to the injected material for a predetermined period of time, and injection. This is performed by carrying out a mold opening step of opening the mold after the solidified material has solidified, a protrusion step of projecting a molded product fixed to the mold, and the like. Further, an injection molding machine that carries out such injection molding includes a plurality of hydraulic actuators for carrying out each process, and a hydraulic supply system for supplying hydraulic oil to these hydraulic actuators. Then, by executing pressure control or flow rate control by the hydraulic supply system, a driving force is generated in the hydraulic actuator to carry out each process.

Patent Document 1 describes a fixed discharge flow rate Qm of a large flow rate and a small flow rate smaller than this large flow rate when variably controlling the rotation speed of a drive motor for driving a hydraulic pump to control each operation process in a molding cycle. Use a hydraulic pump that can set the fixed discharge flow rate Qs. In addition to this, the limit condition based on the threshold value for the load state of the drive motor is set in advance. In Patent Document 1, a predetermined operation process is set to a fixed discharge flow rate Qm of a large flow rate at the time of molding operation to control the operation process, and the load state of the drive motor is monitored, and the load state is a limit condition. When it reaches, it switches to a fixed discharge flow rate Qs with a small flow rate.

According to the control method of Patent Document 1, the optimum threshold value (limit condition) for the drive motor can be set while avoiding the overload of the drive motor. Therefore, it is said that the optimum operating state can be set by avoiding an unnecessarily unnecessary load on the drive motor and the hydraulic pump and increasing the energy consumption.

Further, Patent Document 2 describes a hydraulic pump device capable of switching the discharge capacity in at least two stages of a small discharge capacity and a large discharge capacity having a capacity larger than the small discharge capacity, and driving the hydraulic pump device at a variable speed. We propose a hydraulic pressure control system equipped with a pump. In this hydraulic pressure control system, when the hydraulic pressure pump device is operated with a large discharge capacity and the detected pressure becomes higher than a predetermined deceleration control pressure which is lower than the target pressure at the time of pressure control. , The rotation speed of the motor is gradually reduced, and when the detected pressure exceeds the target pressure, the large discharge capacity is switched to the small discharge capacity. The large discharge capacity corresponds to the large flow rate operation of the present invention, and the small discharge capacity corresponds to the small flow rate operation of the present invention.

According to the hydraulic pressure control system of Patent Document 2, even if the hydraulic pressure pump device is operated with a large discharge capacity and the flow control is changed to the pressure control, the hydraulic pressure pump device is still controlled to the large discharge capacity. .. As a result, there is no momentary pressure drop during the transition from flow rate control to pressure control, the pressure rise during pressure control is steep, the cycle time can be shortened, and the surge pressure is reduced. It is said that it can be done.

Japanese Unexamined Patent Publication No. 2009-285972 Japanese Patent No. 5229092

For example, as described in Patent Document 2, when shifting from flow rate control operating with a large discharge capacity to pressure control and lowering the pressure in the pipeline, the hydraulic pump device is rotated in the normal direction until then. Rotates differently in reverse. This reverse rotation is performed by rotating the drive motor in the reverse direction. In the hydraulic circuit of Patent Document 2, in the step of switching from the flow rate control to the pressure control to reduce the pressure of the first discharge line, the detected pressure of the pressure sensor first exceeds the target pressure. In Patent Document 2, the pump discharge capacity switching calculation unit of the controller performs a process of switching the unload valve to the unload state and switching the discharge capacity of the hydraulic pump device from the large discharge capacity to the small discharge capacity. .. However, the pressure of the first discharge line and the second discharge line may rise sharply, such as when the screw reaches the front end of the cylinder at the time of injection. In this case as well, since the above process is performed, the response time of the pressure sensor, the processing time for instructing the unload valve to perform the switching operation from the pump discharge capacity switching calculation unit of the controller, and the switching operation response time of the unload valve are used. A delay time occurs with respect to the increase in pressure of the 1st discharge line and the 2nd discharge line. Therefore, there is a possibility that a large overshoot may occur in which the pressures of the first discharge line and the second discharge line are relative to the target pressure. Further, this delay time hinders the shortening of the molding cycle time and may not improve the productivity.

Further, in the technique described in Patent Document 2, an unload valve is provided between the first discharge line and the second discharge line and the branch line on the tank side, and the first discharge line and the second discharge line are provided. A check valve is provided between them. Therefore, during this reverse rotation, the oil does not flow into the second discharge line from the first discharge line, and the oil flows back from the tank. In this case, since the flow path resistance due to the throttle action of the unload valve is large, cavitation may occur in the second discharge line and the second fixed pump due to poor oil suction. In order to prevent the occurrence of this cavitation that may damage the pump, it is necessary to reduce the reverse rotation speed of the drive motor, but in this case, the pressure reduction speed of the first discharge line becomes slow.

From the above, the present invention is a hydraulic pressure of an injection molding machine capable of quickly reducing the pressure in the pipe without causing cavitation when shifting from the flow rate control to the pressure control and lowering the pressure in the pipeline. The purpose is to provide a supply system.

The hydraulic supply system of the present invention supplies hydraulic oil to the actuator of an injection molding machine by switching between at least two stages of a small flow rate operation and a large flow rate operation in which the flow rate is larger than the small flow rate operation.
The hydraulic supply system of the present invention has a main hydraulic pump and a sub-hydraulic pump that rotate forward when the hydraulic oil is discharged toward the actuator and reversely when the pressure in the pipe is lowered in pressure control, and a small flow rate operation. At this time, only the hydraulic oil discharged from the main hydraulic pump flows toward the actuator, and the hydraulic oil discharged from both the main hydraulic pump and the sub-hydraulic pump flows toward the actuator during high-flow operation. It includes a main hydraulic oil circuit, a bypass circuit that bypasses the hydraulic oil discharged from the sub-hydraulic pump from the main hydraulic oil circuit and returns it to the oil storage tank during a small flow rate operation, and a logic valve.
The logic valve in the present invention prevents the hydraulic oil discharged from the sub-hydraulic pump from flowing to the bypass circuit during high-flow operation, and when the sub-hydraulic pump rotates in the reverse direction in pressure control, the logic valve passes through the bypass circuit. It is characterized in that the hydraulic oil sucked up from the oil storage tank is allowed to flow to the sub-hydraulic pump.

In the hydraulic supply system of the present invention, the main pipe for flowing the hydraulic oil discharged from the main hydraulic pump toward the actuator and the auxiliary pipe for flowing the hydraulic oil discharged from the sub-hydraulic pump toward the actuator and merging with the main pipe. The main oil supply pipe that allows hydraulic oil to flow from the main pipe to the logic valve, the secondary oil supply pipe that allows hydraulic oil to flow from the secondary pipe to the logic valve, the intake / exhaust pipe that allows hydraulic oil to flow between the logic valve and the oil storage tank, and the main oil supply. A switching valve for switching which of the pipe and the intake / exhaust pipe is communicated with the logic valve is provided.

The logic valve in the present invention may include a first valve chamber communicating with the auxiliary oil supply pipe and a second valve chamber communicating with the connecting pipe.
In this embodiment, the switching valve in the present invention closes the flow path communicating the main oil supply pipe and the second valve chamber when the main hydraulic pump and the sub-hydraulic pump rotate in the reverse direction at the time of small flow rate operation, and at the same time, the first. Open the flow path that connects the valve chamber and the oil storage tank. Further, the switching valve in the present invention opens a flow path that communicates between the main oil supply pipe and the second valve chamber and closes the flow path that communicates between the second valve chamber and the oil storage tank during a large flow rate operation.

From the above, the hydraulic supply system in the present invention operates as follows.
During the small flow rate operation, the hydraulic oil discharged from the sub-hydraulic pump flows to the oil storage tank through the sub-pipe, the sub-fuel supply pipe, the first valve chamber of the logic valve, and the intake / exhaust pipe.
When the main hydraulic pump and the sub-hydraulic pump rotate in the reverse direction, the hydraulic oil sucked up from the oil storage tank is sucked into the sub-hydraulic pump through the intake / exhaust pipe, the first valve chamber of the logic valve and the sub-pipe.
Further, during a large flow rate operation, the hydraulic oil supplied from the main oil supply pipe to the second valve chamber of the logic valve closes the flow path communicating the auxiliary oil supply pipe and the intake / exhaust pipe.

The hydraulic supply system in the present invention preferably includes a pressure sensor that detects the pressure of hydraulic oil flowing through the main pipe.

The sub-pipe in the present invention is provided with a check valve that prevents the hydraulic oil flowing from the main pipe from flowing to the sub-hydraulic pump between the confluence with the main pipe and the position where the sub-fuel supply pipe is connected. Can be done.

The hydraulic supply system in the present invention includes a drive motor that rotates the main hydraulic pump and the sub-hydraulic pump at a variable speed in the forward or reverse rotation, and the main hydraulic pump and the sub-hydraulic pump are interlocked with each other to rotate in the forward or reverse direction. can do.

In the hydraulic supply system of the present invention, the pressure control in which the main hydraulic pump and the sub-hydraulic pump rotate in the reverse direction can be performed in both the small flow rate operation and the large flow rate operation.

The hydraulic system of the present invention includes a logic valve that allows hydraulic oil sucked from an oil storage tank to flow to the sub-hydraulic pump via a bypass circuit when the sub-hydraulic pump rotates in the reverse direction in pressure control. Therefore, according to the present invention, when shifting from flow rate control to pressure control and lowering the pressure in the pipeline, the pressure in the pipe can be quickly reduced without causing cavitation.

It is a figure which shows the schematic structure of the mold clamping device of the injection molding machine which concerns on embodiment of this invention. It is a block diagram which shows the structure of the hydraulic pressure supply system of the mold clamping device in this embodiment. It is a block diagram which shows the structure of the control part of the mold clamping device in this embodiment. It is a block diagram which shows that the hydraulic pressure supply system of this embodiment supplies hydraulic oil by a small flow rate operation. It is a block diagram which shows that the hydraulic pressure supply system of this embodiment supplies hydraulic oil by a large flow rate operation. It is a block diagram which shows that the hydraulic pressure supply system of this embodiment controls pressure. It is a diagram which shows the operation of the process of shifting from the filling process to the pressure holding process by this embodiment. It is a diagram which shows the operation of the process of shifting from a filling process to a pressure holding process by a comparative example. It is a figure which shows the trial calculation about the rotation speed of the reverse rotation of a drive motor by the present inventors.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings, using the mold clamping device 1 of an injection molding machine as an example.
The mold clamping device 1 of the present embodiment rotates forward the rotation of the servomotor 45 as a variable speed drive motor when shifting from flow control to pressure control, for example, in the process of shifting from the filling process to the pressure holding process. It is provided with a hydraulic supply system 30 capable of quickly switching from to reverse rotation. Hereinafter, the configuration and operation of the mold clamping device 1 will be described in this order.

[Structure of mold clamping device 1]
As shown in FIG. 1, the mold clamping device 1 of the present embodiment includes a pair of fixed molds 14 and a movable mold 15 for obtaining a molded product having a desired shape, and a fixed mold 14 and a movable mold 15. An injection cylinder 19 that injects molten resin, which is an injection material, into a cavity formed between the molds, a mold clamping cylinder 18 that generates a driving force for mold clamping, and a hydraulic supply that supplies hydraulic oil to the mold clamping cylinder 18. It includes a system 30 and a controller 80 that controls various configurations.

As shown in FIG. 1, the mold clamping device 1 has a fixed die plate 12 for holding the fixed mold 14 fixedly mounted on the upper surface of the base frame 11 on one end side.
On the upper surface on the other end side of the base frame 11, a moving die plate 13 for holding the movable mold 15 is provided so as to be able to move forward and backward so as to face the fixed die plate 12. A guide rail 26 is laid on the base frame 11, and a linear bearing 27 guided by the guide rail 26 supports the moving die plate 13 via a slide base 28. A sliding plate may be used instead of the linear bearing 27 to support the moving die plate 13 via the slide base 28.

The fixed die plate 12 is provided with mold clamping cylinders 18 which are hydraulic actuators having a small stroke and a large cross-sectional area at four corners thereof. The mold clamping cylinder 18 can also be provided on the moving die plate 13. One end of a tie bar 17 is connected to one side surface of each of the rams 16 sliding in the mold clamping cylinder 18, and the tie bar 17 opens to the moving die plate 13 when the opposing moving die plate 13 approaches due to mold closing. It penetrates the four insertion holes.
A main pipe 51, which will be described later, is connected to the mold clamping cylinder 18, and the main pipe 51 supplies oil to the mold clamping side chamber 181 and the mold opening side chamber 182 of the mold clamping cylinder 18.

A ball screw shaft 25 installed parallel to the moving direction of the moving die plate 13 constitutes a means for moving the moving die plate 13. The ball screw shaft 25 is rotatably supported by the bearing box 20 held by the fixed die plate 12 and the bearing box 21 held by the base frame 11, and is supported by restraining the axial direction, and power is transmitted by the servomotor 22. It is driven via gears 23 and 24. The rotation speed and rotation speed of the ball screw shaft 25 are controlled by the controller 80 via the servomotor 22.
The other end of each tie bar 17 is formed with a plurality of ring-shaped parallel grooves (or spiral threaded grooves) having equal pitches. A half nut 29 that meshes with a ring-shaped parallel groove of each tie bar 17 is provided on the back surface of the moving die plate 13.

The mold clamping device 1 is a servomotor from a state in which the fixed mold 14 and the movable mold 15 are open until the fixed mold 14 and the movable mold 15 are in a closed state as shown in FIG. The moving die plate 13 is moved by the rotation of the ball screw shaft 25 driven by 22. The moving die plate 13 is designed to stop when the fixed mold 14 and the movable mold 15 come into contact with each other.

The half nut 29 operates at the stop position of the moving die plate 13, and the ring-shaped parallel groove inside the half nut 29 engages with the ring-shaped parallel groove at the tip of the tie bar 17, and the tie bar 17 and the half nut 29 And combine. After that, the mold clamping side chamber 181 of the mold clamping cylinder 18 is boosted and the mold is clamped. After the mold is fastened in this way, the molten resin is injected from the injection cylinder 19 into the cavity formed by the fixed mold 14 and the movable mold 15 to mold the molded product.

[Flood supply system 30]
As shown in FIG. 2, the hydraulic supply system 30 connects the hydraulic source 40 that discharges the hydraulic oil toward the mold clamping cylinder 18 and the hydraulic oil that is connected to the hydraulic source 40 and is discharged from the hydraulic source 40 to the mold clamping cylinder 18. The hydraulic oil circuit 50 to be delivered to the vehicle is provided.
The operation of the hydraulic source 40 and the hydraulic oil circuit 50 in the hydraulic supply system 30 is controlled by the controller 80.

[Flood control source 40]
The hydraulic source 40 includes a servomotor 45, an encoder 47 that detects the rotation speed and direction of rotation of the servomotor 45, and a main hydraulic pump 41 and a sub-hydraulic pump 43 that operate by rotationally driving the servomotor 45 to discharge hydraulic oil. And.
The hydraulic supply system 30 molds only the large flow operation that supplies the hydraulic oil discharged from both the main hydraulic pump 41 and the sub-hydraulic pump 43 to the mold clamping cylinder 18 and the hydraulic oil discharged from the main hydraulic pump 41. The operation can be switched between two stages of small flow operation supplied to the cylinder 18.

The servomotor 45 detects the rotation angle by the encoder 47, and outputs the detected rotation angle to the controller 80. The controller 80 generates a pulse signal corresponding to the command value of the rotation speed N of the servomotor 45, outputs the pulse signal to the servomotor 45, and drives the servomotor 45 to rotate at the rotation speed N. The rotation angle detected by the encoder of the servomotor 45 is continuously input to the controller 80, and the controller 80 is a servomotor so that the rotation number N can be obtained while performing feedback correction based on the rotation angle. Control 45.

Here, the servomotor 45 is of any type as long as it is a motor that can be used for controlling the position, speed, and the like in the servo mechanism. For example, an AC servo motor, a DC servo motor, a stepping motor, or the like can be applied. Regarding the structure, for example, the stator structure may be either a distributed winding type or a centralized winding type, and the rotor structure may be either a surface magnet attachment type (SPM) motor or an internal magnet embedded type (IPM) motor.

The main hydraulic pump 41 and the sub-hydraulic pump 43 are both fixed-capacity pumps. For example, if both capacities are the same, the large flow rate operation uses twice the flow rate of hydraulic oil as the small flow rate operation. Can be supplied to 18. However, the capacities of the main hydraulic pump 41 and the sub-hydraulic pump 43 may be different.

[Hydraulic oil circuit 50]
The hydraulic oil circuit 50 is responsible for supplying hydraulic oil discharged from the hydraulic source 40 to the mold clamping cylinder 18 by controlling the flow rate. This basic operation is a small flow rate operation in which only the hydraulic oil from the main hydraulic pump 41 is supplied to the mold clamping cylinder 18, and hydraulic oil from both the main hydraulic pump 41 and the sub-hydraulic pump 43 is supplied to the mold clamping cylinder 18. Includes large flow operation and.
The hydraulic oil circuit 50 includes a pressure control operation in addition to the oil supply operation by the flow rate control. In this pressure control operation, when the detected value of the pressure sensor 55 included in the hydraulic oil circuit 50 reaches the target pressure, the servomotor 45 is operated by switching from the normal rotation to the reverse rotation to lower the pressure. This operation is called a depressurization operation.
The hydraulic oil circuit 50 has the following configurations in order to realize the above refueling operation and depressurization operation.

As shown in FIG. 2, the hydraulic oil circuit 50 mold-clamps the main pipe 51 for flowing the hydraulic oil discharged from the main hydraulic pump 41 toward the mold clamping cylinder 18 and the hydraulic oil discharged from the sub-hydraulic pump 43. A sub-pipe 53 for flowing toward the cylinder 18 is provided. The sub-pipe 53 joins the main pipe 51 at the confluence point JP, which is the downstream end thereof, and the hydraulic oil flowing through the sub-pipe 53 passes through the main pipe 51 downstream from the confluence point JP with the main pipe 51 for mold clamping. It is supplied toward the cylinder 18. In the hydraulic oil circuit 50, the upstream and downstream are based on the direction in which the hydraulic oil flows when the main hydraulic pump 41 and the sub-hydraulic pump 43 are rotated in the forward direction, and the main hydraulic pump 41 and the sub-hydraulic pump 43 are used. It will be located most upstream. Further, the circuit including the main pipe 51 and the sub pipe 53 constitutes the main hydraulic oil circuit of the present invention.

The hydraulic oil circuit 50 includes a pressure sensor 55 that detects the pressure of the hydraulic oil flowing through the main pipe 51. Since the main pipe 51 does not have a valve or other equipment that acts as a flow path resistance between the main hydraulic pump 41 and the pressure sensor 55, the pressure sensor 55 measures the pressure of the hydraulic oil discharged from the main hydraulic pump 41. It can be detected with high accuracy.

The hydraulic oil circuit 50 includes a check valve 57 in the auxiliary pipe 53. The check valve 57 allows the hydraulic oil flowing from the upstream to the downstream with reference to the check valve 57, but blocks the passage of the hydraulic oil in the opposite direction. The check valve 57 prevents the high-pressure hydraulic oil discharged from the main hydraulic pump 41 from being loaded on the upstream sub-hydraulic pump 43 through the sub-pipe 53 during the small flow rate operation. The check valve 57 is provided between the confluence JP of the sub-pipe 53 and the main pipe 51 and the position where the sub-fuel supply pipe 58A connected to the logic valve 70, which will be described later, is connected.

The hydraulic oil circuit 50 includes a bypass circuit 58 that branches from the auxiliary pipe 53.
The bypass circuit 58 is used to bypass the main hydraulic oil circuit and flow the hydraulic oil discharged from the sub-hydraulic pump 43 to the sub-pipe 53 during the small flow rate operation to the oil storage tank 100B.
In the bypass circuit 58, the logic valve 70 is connected in the middle, and the auxiliary oil supply pipe 58A connecting the auxiliary pipe 53 and the logic valve 70, and the intake / exhaust pipe connecting the first valve chamber 77 of the logic valve 70 and the oil storage tank 100B are connected. It is equipped with 58B. Further, the bypass circuit 58 includes a switching valve 60 for switching the flow path for flowing hydraulic oil for operating the logic valve 70 to the second valve chamber 78 of the logic valve 70. Although the oil storage tanks 100A and 100B are distinguished in FIG. 2, they are actually in communication with each other, and the hydraulic oil circulates with each other.

The logic valve 70 causes the hydraulic oil discharged from the sub-hydraulic pump 43 to flow toward the bypass circuit 58 during the small flow rate operation. Further, the logic valve 70 provides a flow path to the bypass circuit 58 in order to allow the hydraulic oil discharged from the sub-hydraulic pump 43 and flowing through the sub-pipe 53 to flow as it is toward the downstream of the sub-pipe 53 during a large flow rate operation. close. Note that FIG. 2 shows the logic valve 70 in the small flow rate operation.

The switching valve 60 includes a valve body 61 and an electromagnetic solenoid 67 that moves the valve body 61.
The valve body 61 includes a first valve body 63 and a second valve body 64.

The switching valve 60 operates as follows when the flow rate operation is small and the main hydraulic pump 41 and the sub-hydraulic pump 43 rotate in the reverse direction. As shown in FIG. 4, the switching valve 60 closes the flow path for supplying the hydraulic oil of the main pipe 51 to the second valve chamber 78, which is the oil chamber for operating the logic valve, by the first valve body 63. Further, the switching valve 60 opens a flow path for communicating the second valve chamber 78 and the oil storage tank 100B by the first valve body 63.
Further, when the switching valve 60 operates at a large flow rate, as shown in FIG. 5, the second valve body 64 opens a flow path for communicating the main pipe 51 and the second valve chamber 78 of the logic valve 70, and at the same time, the second valve body 64 opens a flow path for communicating with the second valve chamber 78 of the logic valve 70. Close the flow path that communicates the two-valve chamber 78 and the oil storage tank 100B.

In the valve body 61, for example, in the off state where the electromagnetic solenoid 67 is not energized, the first valve body 63 is connected to the intake / exhaust pipe 58B as shown in FIGS. 2 and 4. As a result, the second valve chamber 78 is connected to the intake / exhaust pipe 58B via the first valve body 63. At this time, the valve body 61 corresponds to a small flow rate operation or a reverse rotation operation.
Further, in the valve body 61, for example, in the on state where the electromagnetic solenoid 67 is energized, as shown in FIG. 5, the second valve body 64 is connected to the main pipe 51, so that the second valve chamber 78 is formed. It communicates with the main pipe 51 via the second valve body 64. At this time, the valve body 61 corresponds to the large flow rate operation.

The electromagnetic solenoid 67 selectively moves the valve body 61 between a position corresponding to a small flow rate operation and a position corresponding to a large flow rate operation in response to an instruction from the controller 80.

The logic valve 70 includes a valve box 74, a valve body 75 provided inside the valve box 74, and an elastic body 76 that applies an elastic force downward in the drawing to the valve body 75. The valve box 74 is provided on the side of the elastic body 76 with the valve body 75 as a boundary, and has a first valve chamber 77 having a large-diameter inflow / outflow port and a valve body provided on the opposite side of the first valve chamber 77. It has a second valve chamber 78 provided with a pilot port (P port) for driving the 75. The logic valve 70 can supply pilot pressure to the second valve chamber 78 with a small flow rate of hydraulic oil to drive the valve body 75 to open and close the large-diameter flow path of the first valve chamber 77.

The sub refueling pipe 58A connects the sub pipe 53 and the first valve chamber 77 of the valve box 74, and the main refueling pipe 71 connects the switching valve 60 and the main pipe 51. The connecting pipe 79 connects the switching valve 60 and the P port of the second valve chamber 78 of the valve box 74.

The logic valve 70 contracts due to an upward external force applied to the elastic body 76, and when the valve body 75 is displaced to a position where the auxiliary oil supply pipe 58A is closed as shown in FIG. 5, the logic valve 70 is in a closed state in which hydraulic oil does not flow.
On the other hand, in the logic valve 70, unless an upward external force is applied to the elastic body 76 by applying a hydraulic pressure to the second valve chamber 78, the valve body 75 moves downward from the auxiliary oil pipe 58A as shown in FIGS. Separated, the bypass circuit 58 and the auxiliary oil supply pipe 58A communicate with each other to form an open state in which the hydraulic oil flows. The logic valve 70 is a so-called normally open type logic valve.

Next, the operations of the switching valve 60 and the logic valve 70 in the small flow rate operation (FIG. 4), the reverse rotation operation (FIG. 6), and the large flow rate operation (FIG. 5) will be described.
In the small flow rate operation, the electromagnetic solenoid 67 is turned off without energizing, and the second valve chamber 78 and the intake / exhaust pipe 58B are communicated with each other. As a result, the second valve chamber 78 communicates with the oil storage tank 100B via the switching valve 60 and the intake / exhaust pipe 58B. Therefore, the oil pressure in the second valve chamber 78 becomes almost zero (the same pressure as the oil storage tank 100B), so that the logic valve 70 has a force that displaces the valve body 75 of the logic valve 70 upward against the elastic body 76. Is gone. At this time, the valve body 75 is separated from the bypass circuit 58 downward by the elastic body 76 as shown in FIG. 4, so that the hydraulic oil can flow from the sub-pipe 53 to the bypass circuit 58, and the sub-pipe 53 is in an open state. The hydraulic oil is discharged to the oil storage tank 100B through the logic valve 70, the bypass circuit 58, and the intake / exhaust pipe 58B in this order.

Similarly, when the main hydraulic pump 41 and the sub-hydraulic pump 43 rotate in the reverse direction, the electromagnetic solenoid 67 is turned off so that the second valve chamber 78 and the intake / exhaust pipe 58B communicate with each other. As a result, the second valve chamber 78 communicates the oil storage tank 100B with the switching valve 60 and the intake / exhaust pipe 58B. Therefore, since the oil pressure in the second valve chamber 78 becomes almost zero (the same pressure as the oil storage tank 100B), the logic valve 70 does not have a force to displace the valve body 75 upward against the elastic body 76. At this time, the valve body 75 is separated from the bypass circuit 58 downward by the elastic body 76 as shown in FIG. 6, so that the hydraulic oil can flow from the bypass circuit 58 to the sub-pipe 53 in an open state, and the oil storage tank 100B is in an open state. The hydraulic oil flows into the sub-pipe 53 through the intake / exhaust pipe 58B, the bypass circuit 58, and the logic valve 70 in this order.

At the time of high flow rate operation, the electromagnetic solenoid 67 is turned on and the second valve chamber 78 and the main pipe 51 are communicated with each other. As a result, the second valve chamber 78 communicates with the main hydraulic pump 41 via the switching valve 60 and the main oil supply pipe 71. Therefore, when the hydraulic oil discharged from the main hydraulic pump 41 flows into the second valve chamber 78, the hydraulic oil that reaches the second valve chamber 78 instantly pushes the valve body 75 upward against the elastic body 76. Therefore, as shown in FIG. 5, the logic valve 70 is closed. Therefore, the hydraulic oil discharged from the sub-hydraulic pump 43 flows downstream through the sub-pipe 53 without flowing into the bypass circuit 58.

[Controller 80]
Next, the controller 80 will be described with reference to FIG.
The controller 80 has an input unit 81 for inputting control set values, a control unit 83 for generating control commands to the servomotor 45, a switching valve 60, and the like, and a command output unit for outputting control commands generated by the control unit 83. It includes 85 and a storage unit 87 in which various data necessary for generating a control command are stored.

The control unit 83 generates a command for forward rotation or reverse rotation of the servomotor 45, and a command for rotation speed in forward rotation or reverse rotation. The control unit 83 continuously acquires the detected pressure of the pressure sensor 55.
Further, the control unit 83 generates an operation command for the switching valve 60. That is, the control unit 83 selectively generates a command in the off state in which the electromagnetic solenoid 67 is not energized or a command in the on state in which the electromagnetic solenoid 67 is energized.
The above control commands are sent from the command output unit 85 to each device.

The storage unit 87 stores data on a target pressure, which is a threshold value for selecting whether to operate in flow rate control or pressure control, data on a deceleration control pressure lower than the target pressure, and the like.
The control unit 83 continuously compares the data regarding the detected pressure of the pressure sensor 55 and the target pressure, and the data regarding the detected pressure of the pressure sensor 55 and the deceleration control pressure.

[Operation of flood control system 30]
Next, the operation of the hydraulic supply system 30 will be described with reference to FIGS. 4 to 6. Note that FIG. 4 shows a hydraulic supply system 30 performing a small flow rate operation, and FIG. 5 shows a hydraulic supply system 30 performing a large flow rate operation. Both small flow rate operation and large flow rate operation correspond to flow rate control. On the other hand, FIG. 6 shows a hydraulic supply system 30 that controls pressure. In FIGS. 4 to 6, the pipes shown by thick lines indicate that the hydraulic oil is flowing, and the white arrows indicate the direction in which the hydraulic oil flows. Hereinafter, the small flow rate operation, the large flow rate operation, and the pressure control will be described in this order.

[Small flow rate operation (Fig. 4, flow rate control)]
When the hydraulic supply system 30 receives an instruction from the controller 80 to perform a small flow rate operation, the electromagnetic solenoid 67 so that the first valve body 63 of the switching valve 60 connects the second valve chamber 78 and the intake / exhaust pipe 58B. Is driven.
The servomotor 45 rotates at a predetermined rotation speed N based on an instruction from the controller 80, and the main hydraulic pump 41 and the sub-hydraulic pump 43 connected to the servomotor 45 rotate in the forward direction. The main hydraulic pump 41 and the sub-hydraulic pump 43 are mechanically connected and rotate in conjunction with each other.

The hydraulic oil sucked up from the oil storage tank 100A by the forward rotation of the main hydraulic pump 41 is discharged from the main hydraulic pump 41 and then flows through the main pipe 51 toward the mold clamping cylinder 18.

Due to the forward rotation of the sub-hydraulic pump 43, the hydraulic oil sucked up from the oil storage tank 100A flows from the sub-hydraulic pump 43 and then flows through the sub-pipe 53 to reach the logic valve 70. Therefore, the hydraulic oil flows through the logic valve 70 to the bypass circuit 58, and is discharged to the oil storage tank 100B through the intake / exhaust pipe 58B.

As described above, in the small flow rate operation, both the main hydraulic pump 41 and the sub-hydraulic pump 43 are operated, but by controlling the switching valve 60, only the hydraulic oil discharged from the main hydraulic pump 41 is a mold. It is supplied to the tightening cylinder 18.

In the small flow operation, the hydraulic oil discharged from the sub-hydraulic pump 43 returns to the oil storage tank 100B having a small flow path resistance through the logic valve 70, and only the hydraulic oil discharged from the main hydraulic pump 41 flows to the main pipe 51. .. As a result, the target that becomes high pressure in the process of performing the small flow rate operation can be limited to the main hydraulic pump 41, so that there is an advantage that the load torque of the servomotor 45 during the small flow rate operation can be reduced and the size of the servomotor 45 can be reduced. be.

[Large flow rate operation (Fig. 5, flow rate control)]
When the hydraulic supply system 30 receives an instruction from the controller 80 to perform a large flow rate operation, the electromagnetic solenoid 67 so that the second valve body 64 of the switching valve 60 connects the second valve chamber 78 and the main pipe 51. Is driven.
The servomotor 45 rotates at a predetermined rotation speed N based on an instruction from the controller 80, and the double main hydraulic pump 41 and the sub-hydraulic pump 43 connected to the servomotor 45 rotate in the forward direction.

Due to the forward rotation of the main hydraulic pump 41, the hydraulic oil sucked up from the oil storage tank 100A is discharged from the main hydraulic pump 41 and then flows through the main pipe 51 toward the mold clamping cylinder 18. Further, this hydraulic oil flows into the second valve chamber 78 via the switching valve 60 and closes the logic valve 70 as described above.

Due to the forward rotation of the sub-hydraulic pump 43, the hydraulic oil sucked up from the oil storage tank 100A flows through the sub-pipe 53 after being discharged from the main hydraulic pump 41 and reaches the logic valve 70. The flow path to the bypass circuit 58 of the logic valve 70 is closed by the hydraulic oil discharged from the main hydraulic pump 41 into the second valve chamber 78 by the switching valve 60. As a result, the hydraulic oil that has reached the logic valve 70 flows downstream through the auxiliary pipe 53 as it is without flowing into the bypass circuit 58.

As described above, in the large flow operation, both the main hydraulic pump 41 and the sub-hydraulic pump 43 are operated, and the hydraulic oil discharged from the main hydraulic pump 41 and the hydraulic oil discharged from the sub-hydraulic pump 43 are operated. It is supplied to the mold clamping cylinder 18.

[Pressure control (Fig. 6, depressurization control)]
The oil supply system 30 receives an instruction from the controller 80 to perform a pressure control operation. At this time, it is assumed that the second valve body 64 of the switching valve 60 opens the flow path for communicating the second valve chamber 78 and the main pipe 51. If so, the electromagnetic solenoid 67 is driven by the first valve body 63 so as to open a flow path communicating the second valve chamber 78 and the intake / exhaust pipe 58B. The logic valve 70 is a normally open type logic valve 70. Therefore, the valve body 75 is quickly opened without delay even though the oil pressure in the second valve chamber 78 drops by communicating with the oil storage tank 100B via the second valve chamber 78 by the first valve body 63 and the intake / exhaust pipe 58B. Can be operated. In this way, the hydraulic supply system 30 can switch from the large flow rate operation to the small flow rate operation and the pressure control with a high response, so that the overshoot with respect to the target pressure can be suppressed to be small.
However, when the hydraulic supply system 30 receives an instruction to perform a pressure control operation, the second valve body 64 of the switching valve 60 opens a flow path for communicating the second valve chamber 78 and the main pipe 51. Even so, the state in which the flow path communicating the second valve chamber 78 and the main pipe 51 is opened by the second valve body 64 can be maintained as it is.
The servomotor 45 rotates in the reverse direction at a predetermined rotation speed N based on an instruction from the controller 80, and the double main hydraulic pump 41 and the sub-hydraulic pump 43 connected to the servomotor 45 rotate in the reverse direction.

When the main hydraulic pump 41 rotates in the reverse direction, the hydraulic oil existing in the main pipe 51 is extracted and discharged from the main hydraulic pump 41 toward the oil storage tank 100A.

When the sub-hydraulic pump 43 rotates in the reverse direction, the hydraulic oil existing in the sub-pipe 53 is extracted.
On the other hand, the hydraulic supply system 30 sucks up the hydraulic oil of the oil storage tank 100B via the bypass circuit 58. Since the logic valve 70 is a normally open type logic valve 70, the valve body 75 is opened even if the oil pressure in the first valve chamber 77 decreases as the oil pressure in the auxiliary pipe 53 decreases at this time. Can be maintained in position. That is, as shown in FIG. 6, the auxiliary pipe 53 leads to the oil storage tank 100B via the logic valve 70. Therefore, when the sub-hydraulic pump 43 rotates in the reverse direction, the hydraulic oil in the oil storage tank 100B is sucked up through the logic valve 70 of the bypass circuit 58.

Along with the downward restoring force of the elastic body 76 in the figure, the hydraulic oil sucked up from the oil storage tank 100B reaches the first valve chamber 77 and opposes the valve body 75 against the elastic body 76, as shown in FIG. Alternatively, the logic valve 70 opens because it moves together and pushes down downward. Therefore, the hydraulic oil in the oil storage tank 100B is discharged from the sub-hydraulic pump 43 to the oil storage tank 100A after passing through the bypass circuit 58.

Here, assuming that the flow path on-off valve provided in the bypass circuit 58 is not a logic valve 70 having a large flow path cross-sectional area but a flow path cross-sectional area such as a switching valve, the sub-hydraulic pump 43 rotates in the reverse direction. As a result, the hydraulic oil of the oil storage tank 100B is sucked up through the flow path having a small flow path cross-sectional area and a large flow resistance. However, in this case, cavitation may occur in the sub-pipe 53 and the sub-hydraulic pump 43, which may be damaged.

Further, the flood pressure for closing the logic valve 70 loaded on the second valve chamber 78 is substantially the same as the flood pressure for the main pipe 51 and the sub pipe 53 communicating with the first valve chamber 77 for opening the logic valve 70. Therefore, even if the operating load of the hydraulic actuator is large and the operating oil pressure is high and the force for opening the logic valve 70 is large, substantially the same high hydraulic pressure can be applied to the second valve chamber 78. On the contrary, even if the operating load of the hydraulic actuator is small and the operating oil pressure is low and the force for opening the logic valve 70 is small, almost the same low oil pressure can be applied to the second valve chamber 78. As a result, when closing the logic valve 70, it is possible to apply a hydraulic pressure commensurate with the hydraulic pressure for closing the logic valve 70. As described above, according to the present embodiment, since it is not always necessary to supply high hydraulic pressure to the second valve chamber 78 in order to close the logic valve 70, the hydraulic pressure supply system 30 can be operated in an energy-saving manner. can.
The hydraulic supply system in which the logic valve 70 is not provided in the bypass circuit 58 is hereinafter referred to as a comparison system.

As described above, in the pressure control operation, the pressure of the hydraulic oil in the main pipe 51 is controlled by extracting the hydraulic oil from the main pipe 51 by the reverse rotation of the main hydraulic pump 41. Further, in the pressure control operation, when the sub-hydraulic pump 43 rotates in the reverse direction, it circulates between the sub-hydraulic pump 43, the bypass circuit 58, the oil storage tank 100A, and the oil storage tank 100B.

[Operation example of flood control supply system 30]
Next, the operation of the hydraulic supply system 30 will be described by taking as an example a process in which the injection molding machine shifts from the filling process to the pressure holding process. Note that FIG. 7 shows the transition process by the hydraulic supply system 30 of the present embodiment, and FIG. 8 shows the transition process by the comparison system.

When the injection molding machine performs the filling process, the switching valve 60 closes the logic valve 70 because the second valve body 64 communicates the second valve chamber 78 with the main pipe 51 according to the instruction from the controller 80. The hydraulic oil discharged from the pump 43 passes through the sub-pipe 53 as it is and joins the main pipe 51. Since the hydraulic oil is also discharged from the main hydraulic pump 41 to the main pipe 51, the filling step is performed by a large supply flow rate of the main hydraulic pump 41 and the sub-hydraulic pump 43 as shown in FIG. 7 (b). At this time, the rotation speed of the servomotor 45 is controlled so that the discharge flow rates of the main hydraulic pump 41 and the sub-hydraulic pump 43 are set to be large as shown in FIG. 7D during the filling process. NS.

When the filling of the molten resin is completed and the pressure holding step is started, the detected pressure of the pressure sensor 55 gradually increases as shown in FIG. 7A.

Next, as shown in FIG. 7A, when the detected pressure of the pressure sensor 55 exceeds the deceleration control pressure lower than the target pressure at the time of pressure control (target pressure in the pressure holding step), the controller 80 causes the controller 80 to move. As shown in FIGS. 7 (c) and 7 (d), the rotation speed of the servo motor 45 is gradually reduced to gradually reduce the discharge flow rate of the hydraulic oil from the main hydraulic pump 41 and the sub-hydraulic pump 43.

Further, after the pressure sensor 55 detects the target pressure, as shown in FIGS. 7 (b) and 7 (c), the controller 80 changes the operation of the main hydraulic pump 41 and the sub-hydraulic pump 43 from the large flow rate operation to the small flow rate. Move to operation. In addition to this, the controller 80 lowers the rotation speed of the servomotor 45, changes the direction of rotation from the previous forward rotation to the reverse rotation, and performs a depressurization operation. As shown in FIG. 7D, the discharge flow rates of the main hydraulic pump 41 and the sub-hydraulic pump 43 decrease, and when the direction of rotation is switched to the reverse rotation, the discharge flow rate shifts to a negative discharge flow rate, that is, suction.

As the main hydraulic pump 41 rotates in the reverse direction with the reverse rotation of the servomotor 45, the hydraulic oil in the main pipe 51 passes through the main hydraulic pump 41 and reaches the oil storage tank 100A. Therefore, the pressure of the hydraulic oil in the main pipe 51 decreases.
Since the sub-hydraulic pump 43 also rotates in the reverse direction, the hydraulic oil in the oil storage tank 100B is sucked up through the bypass circuit 58 and reaches the oil storage tank 100A through the sub-hydraulic pump 43.

Next, the comparison system will be described with reference to FIG.
The basic behavior is the same as that of the present embodiment shown in FIG. 7, but before the servomotor 45 rotates in the reverse direction, the operation of the main hydraulic pump 41 and the sub-hydraulic pump 43 changes from a large flow rate operation to a small flow rate operation. Transition. The reason for this is as described above.

Further, in order to switch from the large flow rate operation to the small flow rate operation, it is necessary to operate the switching valve 60. Therefore, as shown by the broken line in FIG. 8B, in reality, the switching from the large flow rate operation to the small flow rate operation is performed. Is delayed with respect to the increase in pressure in the main pipe 51 by the response time of the pressure sensor 55, the processing time for instructing the switching valve 60 from the switching operation from the controller 80, and the response time of the switching valve 60. Further, it is necessary to reduce the reverse rotation speed in order to slow down the pressure drop speed in the sub-pipe 53 so that the pressure in the sub-pipe 53 does not become negative pressure and cavitation does not occur.

The hydraulic supply system 30 of the present embodiment performs a depressurization operation via a logic valve 70, whereas the comparison system performs a depressurization operation via a switching valve or the like having a small flow path cross-sectional area.
Therefore, as can be seen by comparing FIGS. 7 (c) and 8 (c), the hydraulic supply system 30 can prevent the occurrence of cavitation in the hydraulic supply system 30 as compared with the comparison system, so that the reverse rotation of the servomotor 45 is faster. Since it can be performed with, the pressure release can be performed quickly. As a result, as shown in FIGS. 7 (a) and 8 (a), the hydraulic pressure supply system 30 returns to the target pressure, specifically, the time for the pressure to drop down to the target pressure is shorter than that of the comparison system.

[effect]
Hereinafter, the effect of the hydraulic pressure supply system 30 of the present embodiment will be described.
First, the hydraulic supply system 30 performs a depressurization operation via a bypass circuit 58 that bypasses the hydraulic oil discharged from the sub-hydraulic pump 43 from the main hydraulic oil circuit and returns it to the oil storage tank 100B during the small flow rate operation. Moreover, the hydraulic supply system 30 uses a logic valve 70 having a large flow path cross-sectional area and a small flow path resistance. Therefore, it is possible to prevent the occurrence of cavitation when the servomotor 45 is switched to reverse rotation.

Further, since the hydraulic pressure supplied to close the logic valve 70 can be set to an appropriate hydraulic pressure corresponding to the hydraulic pressure to close the logic valve 70, the energy saving of the hydraulic pressure supply system 30 can be achieved.
Here, in the comparison system, if the sub-hydraulic pump 43 rotates in the reverse direction, the hydraulic oil is sucked up from the oil storage tank 100B via the sub-pipe 53, the switching valve having a small flow path cross-sectional area, and the like. However, since the switching valve and the like have a large flow path resistance, cavitation may occur in the sub-hydraulic pump 43 and the sub-hydraulic pump 43 may be damaged.

Next, the logic valve 70 used for the depressurization operation has a small flow path resistance, that is, a pressure loss. As a result, it is possible to prevent the pressure in the auxiliary pipe 53 from becoming a negative pressure when sucking up the hydraulic oil, and it is possible to increase the rotation speed of the servomotor 45 that rotates in the reverse direction without fear of cavitation. Therefore, according to the present embodiment, the pressure in the pipe can be quickly reduced.
On the other hand, in the comparison system, since the flow path resistance is large, the pressure in the auxiliary pipe 53 tends to be negative at the time of suction, so that the servomotor 45 rotates in the reverse direction to prevent the occurrence of cavitation. The speed stays low.

FIG. 9 shows a trial calculation result relating to the rotation speed of the servomotor 45 by the present inventor. FIG. 9 shows the hydraulic actuator side generated when a hydraulic pump having a pump size of 20 cc / rev and a pump suction allowable suction resistance value of 0.214 kgf / cm ² is rotated in reverse at rotation speeds of 3000 rpm, 1000 rpm, and 800 rpm, respectively. This is a trial calculation comparison of the hydraulic oil flow rate Qb flowing back to the hydraulic pump side, the comparison system for the backflow flow rate Qb, and the pressure drop value of each of the hydraulic valves in the logic valve corresponding to the present embodiment. Here, when the pressure drop value generated in the hydraulic valve portion exceeds the pump suction allowable suction resistance value, the hydraulic pump is damaged due to the cavitation generated between the hydraulic valve and the hydraulic pump.
As shown in Case 1 of FIG. 9, the logic valve 70 has a pressure drop value of 0.071 kgf / cm ² even when the maximum reverse rotation speed is 3000 rpm, and a suction allowable resistance value (0.214 kgf / 0.214 kgf /) of the pump. Since ^{it is sufficiently small with respect to cm 2} ), damage to the pump can be prevented. On the other hand, in order to obtain a pressure drop value similar to that of the present embodiment in the comparison system, the reverse rotation speed must be reduced to a reverse rotation speed of about 800 rpm (Case 2, Comparison System Example 2). Further, in the case of the configuration of the hydraulic equipment shown in FIG. 9, the time T2 for switching the pump discharge capacity from the large discharge capacity to the small discharge capacity in the comparison system and lowering the pressure detection value by the pressure sensor 55 to the target pressure value is about about. While 1 second is required, the time T1 for the pressure detected value by the pressure sensor 55 to decrease from the switching of the pump discharge capacity of the present embodiment from the large discharge capacity to the small discharge capacity to the target pressure value is about 0. It can be 3 seconds.

On the other hand, in the comparison system, if the servomotor 45 is rotated in the reverse direction, the sub-hydraulic pump 43 may be damaged. Therefore, in this case, it is necessary to reverse-rotate the servomotor 45 at a low speed after the bypass circuit 58 is surely switched from the large flow rate operation to the small flow rate operation.

Next, in the hydraulic supply system 30, the pressure sensor 55 is the main pipe 51 and is provided on the secondary side of the main hydraulic pump 41, and there are valves between the main hydraulic pump 41 and the pressure sensor 55. Therefore, the pressure detected by the pressure sensor 55 and the discharge pressure of the main hydraulic pump 41 are substantially the same. Therefore, the hydraulic pressure supply system 30 can normally perform pressure control.

Although the preferred embodiments of the present invention have been described above, the configurations listed in the above embodiments can be selected or appropriately changed to other configurations as long as the gist of the present invention is not deviated.
For example, in the present embodiment, the reverse rotation operation of the sub-hydraulic pump 43 is performed based on the instruction from the controller 80, but the present invention is not limited to this. For example, the reverse rotation caused by the backflow from the main pipe 51 to the oil storage tank 100A due to the pressure difference between the pressure in the main pipe 51 and the pressure in the oil storage tank 100A is used to make the main hydraulic pump 41. The connected sub-hydraulic pump 43 may be rotated in the reverse direction.

Further, in the present embodiment, the switching valve 60 is provided so that the second valve chamber 78 of the logic valve 70 communicates with the main pipe 51, but in the present invention, the second valve chamber 78 is not the main pipe 51 but the sub pipe 53. A switching valve 60 may be provided so as to communicate with the switch valve 60.
However, from the viewpoint of performing the closing operation of the logic valve 70 with a high response when closing the logic valve 70 in order to switch from the small flow rate operation or the reverse rotation operation to the large flow rate operation, the second valve chamber 78 according to the present embodiment. It is preferable to provide a switching valve 60 so as to communicate with the main pipe 51.

Specifically, when the switching valve 60 is provided so that the second valve chamber 78 communicates with the auxiliary pipe 53, the oil pressures of the first valve chamber 77 and the second valve chamber 78 of the logic valve 70 become substantially the same. As a result, the force for moving the valve body 75 toward the closing side (upper in FIGS. It is the difference between the force in the opening direction due to the hydraulic pressure acting on the valve chamber 77 and the sum of the forces in the opening direction (lower direction in the figure) of the elastic body 76. At this time, although the pressure receiving area of the second valve chamber 78 is larger than the pressure receiving area of the first valve chamber 77, when a hydraulic pressure of the same pressure acts on the second valve chamber 78 and the first valve chamber 77, the force of the elastic body 76 is applied. Therefore, the force for moving the valve body 75 in the closing direction is small. In this state, at the moment of switching to the small flow rate operation or the moment of switching to the reverse rotation operation, the hydraulic oil of the sub-pipe 53 communicates with the oil storage tank 100B via the bypass circuit 58, and the oil pressure of the sub-pipe 53 suddenly increases. The pressure drops to almost zero (the same pressure as the oil storage tank 100B). As a result, the sum of the force in the closing direction due to the hydraulic pressure acting on the second valve chamber 78 during the step-down process, the force in the opening direction due to the hydraulic pressure acting on the first valve chamber 77, and the force in the opening direction of the elastic body 76. The absolute value of the difference is very small. Therefore, the movement of the valve body 75 to the closed side performed by this minute pushing force tends to be slow and unstable.

On the other hand, the flood pressure of the main pipe 51 is in a high pressure state because it drives the hydraulic actuator even during a small flow rate operation. Therefore, when the switching valve 60 is switched, the high pressure hydraulic pressure can be instantaneously supplied to the second valve chamber 78, so that the valve body 75 can be moved to the closed side with a high response.

Further, in the present embodiment, the filling process and the pressure holding process have been described as an example of switching between the large flow rate operation and the small flow rate operation, but the present invention describes the large flow rate operation and the small flow rate operation in any process applied to injection molding. It can also be applied to switching flow rate operations.

Further, in the injection molding machine, the part to which the hydraulic supply system of the present invention is applied is arbitrary, and can be applied to the hydraulic actuator of the part other than the mold clamping device.
Further, the configuration of the mold clamping device 1 shown above is merely an example, and elements not included in the mold clamping device 1 may be included, or elements included in the mold clamping device 1 may be omitted.

1 Mold clamping device 12 Fixed die plate 13 Moving die plate 14 Fixed mold 15 Movable mold 17 Tie bar 18 Mold clamping cylinder 19 Injection cylinder 30 Hydraulic supply system 40 Hydraulic source 41 Main hydraulic pump 43 Sub-hydraulic pump 45 Servo motor 47 Encoder 50 Hydraulic oil circuit 51 Main piping 53 Sub piping 55 Pressure sensor 57 Check valve 58 Bypass circuit 58A Sub oil supply pipe 58B Intake and exhaust pipe 60 Switching valve 61 Valve body 63 First valve body 64 Second valve body 67 Electromagnetic solenoid 70 Logic valve 71 Main Refueling pipe 74 Valve box 75 Valve body 76 Elastic body 77 First valve chamber 78 Second valve chamber 79 Connection pipe 80 Controller 81 Input unit 83 Control unit 85 Command output unit 87 Storage unit 100A, 100B Oil storage tank

Claims (8)

A flood control system that supplies hydraulic oil to the actuator of an injection molding machine by switching between at least two stages, a small flow rate operation and a large flow rate operation with a larger flow rate than the small flow rate operation.
A main hydraulic pump and a sub-hydraulic pump that rotate forward when the hydraulic oil is discharged toward the actuator and rotate in the reverse direction when the pressure in the pipe is reduced in pressure control.
Only the hydraulic oil discharged from the main hydraulic pump flows toward the actuator during the small flow rate operation, and is discharged from both the main hydraulic pump and the sub-hydraulic pump during the large flow rate operation. A main hydraulic oil circuit that allows the hydraulic oil to flow toward the actuator,
A bypass circuit that bypasses the hydraulic oil discharged from the sub-hydraulic pump from the main hydraulic oil circuit and returns it to the oil storage tank during the small flow rate operation.
During the large flow rate operation, the hydraulic oil discharged by the sub-hydraulic pump is prevented from flowing into the bypass circuit, and
In the pressure control, when the sub-hydraulic pump rotates in the reverse direction, a logic valve that allows the hydraulic oil sucked up from the oil storage tank through the bypass circuit to flow to the sub-hydraulic pump is provided.
A hydraulic supply system characterized by that.
A main pipe that allows the hydraulic oil discharged from the main hydraulic pump to flow toward the actuator, and
A sub-pipe that allows the hydraulic oil discharged from the sub-hydraulic pump to flow toward the actuator and merges with the main pipe.
A main oil supply pipe for flowing the hydraulic oil from the main pipe to the logic valve,
An auxiliary oil supply pipe for flowing the hydraulic oil from the auxiliary pipe to the logic valve,
An intake / exhaust pipe through which the hydraulic oil flows between the logic valve and the oil storage tank,
A switching valve for switching which of the main oil supply pipe and the intake / exhaust pipe communicates with the logic valve is provided.
The hydraulic supply system according to claim 1.
The logic valve is
It is provided with a first valve chamber that communicates with the sub-fuel supply pipe and a second valve chamber that communicates with the connecting pipe.
The switching valve is
During the small flow rate operation and when the main hydraulic pump and the sub-hydraulic pump rotate in the reverse direction, the flow path communicating the main oil pipe and the second valve chamber is closed, and the second valve chamber and the second valve chamber are closed. Open the flow path that communicates with the oil storage tank
At the time of the large flow rate operation, the flow path communicating the main oil supply pipe and the second valve chamber is opened, and the flow path communicating the second valve chamber and the oil storage tank is closed.
The hydraulic supply system according to claim 2.
During the small flow rate operation
The hydraulic oil discharged from the sub-hydraulic pump flows to the oil storage tank through the sub-pipe, the sub-fuel supply pipe, the first valve chamber of the logic valve, and the intake / exhaust pipe.
When the main hydraulic pump and the sub-hydraulic pump rotate in the reverse direction,
The hydraulic oil sucked up from the oil storage tank is sucked into the sub-hydraulic pump through the suction / exhaust pipe, the first valve chamber of the logic valve, and the sub-pipe.
During the large flow rate operation
The hydraulic oil supplied from the main oil supply pipe to the second valve chamber of the logic valve closes the flow paths of the auxiliary oil supply pipe and the intake / exhaust pipe.
The hydraulic supply system according to claim 3.
A pressure sensor for detecting the pressure of the hydraulic oil flowing through the main pipe is provided.
The hydraulic supply system according to any one of claims 2 to 4.
The sub-pipe
A check valve for preventing the hydraulic oil flowing from the main pipe from flowing to the sub-hydraulic pump is provided between the confluence point with the main pipe and the position where the sub-fuel supply pipe is connected.
The hydraulic supply system according to any one of claims 2 to 5.
A drive motor for rotating the main hydraulic pump and the sub-hydraulic pump at a variable speed in the forward or reverse rotation is provided.
The main hydraulic pump and the sub-hydraulic pump are interlocked with each other to rotate forward or reverse.
The hydraulic supply system according to any one of claims 1 to 6.
The pressure control in which the main hydraulic pump and the sub-hydraulic pump rotate in the reverse direction
It is performed in both the small flow rate operation and the large flow rate operation.
The hydraulic supply system according to any one of claims 1 to 7.

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