JP2003278707A - Hydraulic controlling method of injection molder, and control device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic controlling method of an injection molder allowing to feed hydraulic oil discharged from two hydraulic pumps to each of a plurality of actuators as well as to make the fluid merge and feed to a predetermined molding and dwelling cylinder and to operate with reduced energy during the dwelling process. <P>SOLUTION: In a hydraulic controlling device, the hydraulic oil discharged from first and second variable displacement hydraulic pumps 21A, 21B that are mechanically connected and driven is fed to a mold opening and closing cylinder 16, the molding and dwelling cylinder 4 and the hydraulic motor 7. When the hydraulic oil discharged from the first and second hydraulic pumps 21A, 21B is merged by first and second connecting pipes 31A, 31B and fed and dwelt into the molding and dwelling cylinder 4, if a dwelling pressure value detected by a pressure sensor 8 fixed in the molding and dwelling cylinder 4 reaches a set pressure value, the discharge quantity of the first hydraulic pump 21A is controlled to be zero. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention drives a plurality of mechanically coupled variable displacement hydraulic pumps by an electric motor, and at that time, a plurality of hydraulic oils are discharged from each of the hydraulic pumps. A plurality of operations of supplying each of the actuators and a single operation of supplying the operating oil discharged from each of the hydraulic pumps into a unidirectional flow and supplying the selected actuator of the plurality of actuators are appropriately performed. The present invention relates to a hydraulic control method and a hydraulic control device for an injection molding machine configured as described above.

[0002]

2. Description of the Related Art In hydraulically driven industrial machines, a hydraulic cylinder for adjusting the elevation angle of an arm, a hydraulic pressure for winding or unwinding a wire suspended from the tip of the arm, as is seen in, for example, mobile cranes. A plurality of actuators such as motors are provided. Further, a plurality of hydraulic pumps are provided to supply hydraulic oil to each of these actuators. A relatively inexpensive constant displacement type hydraulic pump is applied to these hydraulic pumps, and an unload valve, a pressure adjusting valve, and a flow rate adjusting device for releasing the pressure oil to the tank are installed in the hydraulic pipe line connecting the hydraulic pump and the actuator. The valves and the like are individually interposed. The plurality of hydraulic pumps are driven by one electric motor.

Therefore, when the electric motor is started, a plurality of hydraulic pumps are driven at the same time. Therefore, the unload valve, the pressure adjusting valve, the flow rate adjusting valve, etc. are appropriately adjusted, and the direction switching valve is used to control the flow direction of the hydraulic oil. By appropriately selecting, it is possible to supply the hydraulic oil to a predetermined position of each actuator and independently perform a predetermined work. By the way, since a hydraulic pump having a constant capacity is applied to the above-mentioned conventional hydraulic drive device, an unload valve, a pressure adjusting valve, etc. are required for each hydraulic pump, and the hydraulic circuit is complicated. Further, since the hydraulic pump has a constant capacity, there is a drawback that the flow rate control of the hydraulic oil is particularly required.

On the other hand, the variable displacement hydraulic pump is
It has an advantage that the unload valve, the pressure adjusting valve, the flow rate adjusting valve and the like as described above are unnecessary. Further, the medium or small-sized variable displacement hydraulic pump has an advantage that it is relatively inexpensive. However, a large capacity variable displacement hydraulic pump becomes expensive. Therefore, a hydraulic system that combines multiple small and medium-sized variable displacement hydraulic pumps that can be obtained at low cost and drives a large capacity actuator is also available.
For example, it is proposed by Japanese Patent Laid-Open No. 2000-274406.

Although the above publication discloses a general hydraulic control system, a concrete example in which the system is applied to a hydraulically driven injection molding machine is shown in FIG. That is, in FIG. 5, reference numeral 100 denotes an injection device, and 10
Reference numeral 5 denotes mold clamping devices. Injection device 100
As is well known in the art, includes a screw 101 that is driven in the heating cylinder in the rotational direction and the axial direction. This screw 101 is rotationally driven by a hydraulic motor 102,
The piston 103 of the injection cylinder is driven in the axial direction independently of rotation. Mold clamping device 10
5 includes a toggle type mold clamping device 107 driven by a mold opening / closing cylinder 106, a movable platen 108 to which a link is attached, and a fixed platen 109 to a fixed platen, respectively. ing.

The hydraulic circuit for supplying hydraulic oil to the injection device 100 and the mold clamping device 105 is provided with two variable displacement type first and second hydraulic pumps 111A and 111B.
And, these first and second hydraulic pumps 111A, 11
1B is mechanically connected and driven by one electric motor 110. The first variable displacement hydraulic pump 111A includes a first flow rate detector 113A, a plurality of control valves, and the like, and is provided with a first control valve 112A for adjusting the discharge amount. In the first discharge pipe 115A of the first hydraulic pump 111A, a closed one-way type rotary switching valve 116 and a closed center type injection / holding pressure switching valve 117 are provided on the downstream side thereof in reverse order. A stop valve 118 is interposed. The first discharge pipe 115A ′ is connected to the closed center type merge switching valve 120.
Is connected to the specified port. The discharge-side port of the rotation switching valve 116 is connected to the hydraulic motor 102, and the two discharge-side ports of the injection / holding switching valve 117 are connected to the piston head side and the piston rod side of the injection cylinder 103, respectively. Has been done.

The second variable displacement hydraulic pump 111B is also provided with a second control valve 112B which comprises a second flow rate detector 113B, a plurality of control valves and the like and changes the discharge amount. The second variable displacement hydraulic pump 111
A closed center type merge switching valve 120 is interposed in the second discharge pipe 115B of B and leads to a similar closed center type mold switching valve 121. Mold open / close switching valve 1
The two outlet ports 21 are connected to the piston head side and the piston rod side of the mold opening / closing cylinder 106, respectively.

Therefore, when the electromagnetic coil b of the merging switching valve 120 is energized to switch to the Y position, the end of the first discharge pipe 115A is connected to the tank T, but the check valve 118 causes the flow to the tank T. Is blocked. The second discharge pipe 115B is connected to the mold open / close switching valve 121. Therefore, when a command signal of the discharge amount is output from the first and second operation command devices 114A and 114B to the first and second control valves 112A and 112B, the variable displacement first and second hydraulic pumps 11 are generated.
A predetermined amount of hydraulic oil is discharged from 1A and 111B. As a result, the injection device 100 and the mold clamping device 105 can be independently driven as is conventionally known. That is, when the electromagnetic coil a of the injection / pressure holding switching valve 117 is energized to switch to the X position and the electromagnetic coil a of the rotation switching valve 116 is energized, the hydraulic motor 102 rotates and the screw 101 is rotationally driven. . As a result, the resin is melted and measured, as is well known in the art. Further, the rotation switching valve 116 is switched to the Z position shown in FIG. 5, and the electromagnetic coils a and b of the injection / pressure holding switching valve 117 are appropriately energized or turned off, whereby the first discharge pipe 115A. The hydraulic oil therein is supplied to the piston head side or the piston rod side of the injection piston 103, and the measured molten resin is injected into the cavities of the molds 108 and 109, and is held or sucked back. On the other hand, the movable mold 108 can be opened / closed by switching the mold opening / closing switching valve 121 interposed in the second discharge pipe 115B ′ to the X or Y position.

When the electromagnetic coil a of the merge switching valve 120 is energized and switched to the X position, the pipe 115B 'connected to the mold opening / closing switching valve 121 is connected to the tank T, but the second discharge pipe 115B is No. 1 discharge pipe 115A. As a result, the hydraulic oil discharged from the second hydraulic pump 111B passes through the check valve 118, and the first discharge pipe 11
It flows toward 5A. By appropriately switching the rotation switching valve 116 or the injection / holding pressure switching valve 117 as described above, high-speed metering and high-speed injection can be performed with a large amount of combined hydraulic oil discharged from the first and second hydraulic pumps 111A and 111B. it can.

[0010]

In the conventional hydraulic system described above, when the merging switching valve 120 is switched to the Y position, the first discharge pipe 115A is provided with the check valve 118. There is an advantage that hydraulic oil can be individually supplied to the actuator, that is, the hydraulic motor 102 and the mold opening / closing cylinder 106, and can be operated individually. Also,
When the merging switching valve 120 is switched to the X position, the second
Since the discharge pipe 115B of No. 1 communicates with the first discharge pipe 115A, the hydraulic oil discharged from the first and second hydraulic pumps 111A and 111B joins the first discharge pipe 115A. Therefore, the advantage that high-speed metering with a large amount of combined hydraulic oil and high-speed injection is possible is also recognized. However, there are many problems to be improved. For example,
The combined operating oil cannot be supplied to the mold opening / closing cylinder 106, and the usability is not necessarily good. In particular, it becomes a problem when the mold opening / closing cylinder 106, that is, the other actuator also needs to be driven at high speed. Further, when the hydraulic oil 102 is plasticized by the combined hydraulic oil, the screw 101 may bite into the resin material, and the rotational load pressure may become high, which may result in the rotation failure. Since it is not present, one of the first hydraulic pumps 111A may be damaged. That is,
When it becomes impossible to rotate, the first and second discharge pipes 115A, 115
Although the pressure in B rises, since the one-way check valve 118 is merely provided as a check valve, the high-pressure hydraulic oil discharged from the second hydraulic pump 111B is used as the check valve 118. There is also a risk of backflow toward the first hydraulic motor 111A through the pump and damage to the pump 111A. Further, although the combined hydraulic oil can be injected at a higher speed, the electric motor 110 is the first and second hydraulic motors 1 in spite of the pressure control in the pressure holding step, not the flow rate control.
Since 11A and 111B are continuously driven, there is energy loss. The problems described above are
The same is true for hydraulically driven general industrial machines.

It is an object of the present invention to provide a hydraulic control method and a hydraulic control device that solve the above-mentioned problems, and specifically, a plurality of hydraulic oils discharged from a plurality of hydraulic pumps are used. An injection molding machine that can supply energy to each of the actuators, combine hydraulic oil and supply it to a predetermined actuator, and prevent backflow of hydraulic oil between a plurality of hydraulic pumps, and further enable energy saving operation. It is an object of the present invention to provide a hydraulic control method and a hydraulic control device.

[0012]

In order to achieve the above object, the invention described in claim 1 drives a plurality of mechanically coupled variable displacement hydraulic pumps by an electric motor, and At this time, a plurality of operations for supplying the hydraulic oil discharged from each of the hydraulic pumps to each of the plurality of actuators, and the hydraulic oil discharged from each of the hydraulic pumps are merged into a unidirectional flow to form a plurality of actuators. A hydraulic control method for appropriately performing a single operation of supplying the selected actuator, wherein the hydraulic oil discharged from each of the hydraulic pumps is merged with a flow in another direction to perform the single operation. Other independent movements of the plurality of actuators to supply other selected actuators are also included. According to a second aspect of the present invention, in the hydraulic control method according to the first aspect, when an excessive load is generated during a single operation, the circuit for joining the hydraulic oil discharged from the plurality of hydraulic pumps is shut off. According to the invention described in claim 3, in the hydraulic control method according to claim 1, when an excessive load exceeding a set pressure value is generated in a single operation, the hydraulic pressure is discharged from a plurality of hydraulic pumps. The circuit for joining the hydraulic oil is cut off, and the control pressure of each hydraulic pump is set to zero.
According to a fourth aspect of the present invention, a plurality of mechanically coupled variable displacement hydraulic pumps are driven by an electric motor, and the hydraulic fluid discharged from each of the hydraulic pumps at that time is stored in a plurality of actuators. A plurality of operations for supplying the hydraulic oil to each of the hydraulic pumps and a single operation for supplying the hydraulic oil discharged from each of the hydraulic pumps to a selected injection / pressure holding cylinder of the plurality of actuators. A hydraulic control method that is appropriately performed, wherein when the pressure holding step is performed by the injection / pressure holding cylinder during the single operation,
When the holding pressure value measured by the holding cylinder reaches a set pressure value, the discharge amount of a predetermined hydraulic pump of the plurality of hydraulic pumps is set to zero. The invention according to claim 5 is provided with a plurality of variable displacement hydraulic pumps that are mechanically coupled and driven, and a plurality of control valves, and the hydraulic oil discharged from the plurality of hydraulic pumps. Is a hydraulic control device adapted to be supplied to a plurality of actuators, each discharge pipe of the plurality of hydraulic pumps is connected to a predetermined actuator of the plurality of actuators, The discharge pipes are connected to each other on the upstream side of the actuator by a communication pipe in which the plurality of control valves are interposed, and when a predetermined control valve of the control valve is energized, the discharge pipe is When one of the discharge pipes communicates with the other discharge pipe via the communication pipe and another predetermined control valve of the control valve is energized, the other discharge pipe of the discharge pipes causes the communication pipe to operate. Via one of the discharge pipes According to a sixth aspect of the present invention, in the hydraulic control device according to the fifth aspect, when an excessive load is generated in the discharge pipe, the communication pipe is shut off by the control valve. According to a seventh aspect of the present invention, in the hydraulic control device according to the fifth aspect, the discharge pipe is provided with a pressure sensor, and when an excessive load is generated in the discharge pipe, the communication pipe is shut off by the control valve. Along with, when the detected pressure value detected by the pressure sensor exceeds a set pressure value, the control pressure of the hydraulic pump is controlled to be zero.
The invention according to claim 8 is provided with a plurality of variable displacement hydraulic pumps that are mechanically coupled and driven, and a plurality of control valves, and an operation for discharging from the plurality of hydraulic pumps. A hydraulic control device adapted to supply oil to a plurality of actuators, wherein each discharge pipe of the plurality of hydraulic pumps has a predetermined actuator of the plurality of actuators and a plurality of the plurality of actuators. The discharge pipe is connected to a selected injection / pressure-holding cylinder of an actuator, and the discharge pipes are connected to each other by a connecting pipe in which the plurality of control valves are interposed upstream of the actuator, When a predetermined control valve of the control valve is energized, one discharge pipe connected to the predetermined actuator is connected to the injection / pressure-holding cylinder via the communication pipe. When the holding pressure value communicated with the other discharge pipe that is detected by the pressure sensor provided in the injection / pressure holding cylinder reaches a set pressure value, the predetermined hydraulic pump of the hydraulic pumps The discharge amount is controlled to be zero.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention can be applied to a metal material injection molding machine as well as a general hydraulic drive type industrial machine, but hereinafter, a hydraulic injection molding machine mainly for a resin material is used. The embodiment applied to is explained. 1 to 4 showing the embodiment of the present invention, the pipeline through which the hydraulic oil flows is a solid line, the pilot pipe through which the pilot oil flows is a relatively thin chain line, and the electric signal line is a relatively thick chain line. It is shown. Further, the injection molding machine according to the present embodiment is also provided with a control device, and various valves described later can be automatically switched and automatic molding can be performed, but a general control for such an injection molding machine is possible. The device is not shown in the figure.

As shown in FIG. 1, the injection molding machine according to the present embodiment has an injection device 1 as well known in the art.
And the mold clamping device 10. The injection device 1 includes a heating cylinder 2 and a screw 3 provided in the heating cylinder 2 so as to be drivable in the rotation direction and the axial direction. An injection / pressure-holding cylinder 4 is provided on the rear portion of the screw 3 on the right side in FIG. 1, and a hydraulic motor 7 is provided on the rear portion thereof. The shaft of the screw 3 is mechanically connected to the injection / holding cylinder 4 and the hydraulic motor 7 outside the heating cylinder 2 by a conventionally known spline mechanism or the like. Therefore, for example, even when the screw 3 is rotationally driven by the hydraulic motor 7, hydraulic oil can be supplied to the piston rod chamber 5 of the injection / pressure holding cylinder 4 to suck back. Further, the piston 3 can be supplied to the piston head chamber 6 to apply back pressure to the screw 3. In the piston head chamber 6 of the injection / pressure holding cylinder 4,
A pressure sensor 8 for detecting the injection pressure or the holding pressure is attached. In the above embodiment, the hydraulic motor 7 and the injection / pressure holding cylinder 4 constitute an actuator.

As is well known in the art, the mold clamping device 10 comprises a fixed mold 11 mounted on a fixed platen and a movable mold 12 mounted on a movable platen. And
In the embodiment shown in FIG. 1, a toggle type mold clamping device 1
By 3, the movable plate can be opened and closed with respect to the fixed plate. The toggle type mold clamping device 13 is driven by a mold opening / closing cylinder 16 having a piston head chamber 14 and a piston rod chamber 15. The mold opening / closing cylinder 16 also constitutes an actuator.

The hydraulic circuit for supplying the hydraulic oil to the injection device 1 and the mold clamping device 10 has, for example, two variable capacities for changing the discharge amount by adjusting the inclination angle of the swash plate of the plunger or the eccentric amount of the ring. Type first and second hydraulic pumps 21A, 2
It is equipped with 1B. First and second hydraulic pumps 21A, 21
A hydraulic pump having the same capacity can be applied to B, and as described later, the first and second hydraulic pumps 21
When the hydraulic oil discharged from each of A and 21B is supplied to each hydraulic motor 7 and the mold opening / closing cylinder 16, for example, when the metal material is injected at a high injection speed, the second hydraulic pressure is used. A hydraulic pump having a relatively large capacity can be applied to the pump 21B. Such variable displacement first and second hydraulic pumps 21
A and 21B are mechanically connected to one electric motor 20.
It is designed to be driven by.

The first hydraulic pump 21A is provided with a first control valve 22A composed of a plurality of valves for controlling the discharge amount thereof. A control signal, for example, a signal for reducing the discharge amount and the pressure to zero at the time of the pressure-holding process or at the time of metering abnormality, is input to the first control valve 22A from the first operation command device 24A. There is. Further, the discharge amount is detected by the first flow rate detector 23A. As described above, according to the present embodiment, since the first control valve 22A is provided, it is possible to input a control signal from the first operation command device 24A to adjust the predetermined discharge amount. A control device for issuing such a general control signal is not shown in FIG. 1 as mentioned above. The second hydraulic pump 21B is also provided with a second control valve 22B that controls the discharge amount and that includes a plurality of valves. Then, a control signal, for example, a signal for making the discharge amount and the discharge pressure zero when an abnormality occurs during mold opening / closing, is input to the second control valve 22B from the second operation command device 24B. . Further, the discharge amount is detected by the second flow rate detector 23B.

A first discharge pipe 30A is attached to the discharge port of the first hydraulic pump 21A configured as described above. The first discharge pipe 30A extends to the mold open / close switching valve 35. And the 1st connection pipe 31A has branched in the middle. This first connecting pipe 31A is
The first sequence valve 32A or the second sequence valve 32B, which will be described later, is also connected to the second communication pipe 31B, which is also described later. On the other hand, the second hydraulic pump 21B
A second discharge pipe 30B is also attached to the discharge port of the second discharge pipe 30B, and the second discharge pipe 30B extends toward the injection / pressure holding switching valve 36 and the rotation switching valve 37. A second communication pipe 31B branches off from the second discharge pipe 30B. Since the first connecting pipe 31A is connected to the second connecting pipe 31B as described above, the second connecting pipe 31B
Is connected to the first communication pipe 31A. That is, the second connecting pipe 31B is connected to the first sequence valve 32.
It is connected to the first communication pipe 31A via A or the second sequence valve 32B. Therefore, the first and second discharge pipes 30A and 30B are the same as the first and second connecting pipes 31A and 31B.
It means that they are in communication via B.

The mold opening / closing changeover valve 35 is composed of a closed center type electromagnetic directional changeover valve. When the X position is switched, the mold is closed, when the Y position is switched, the mold is opened, and when the Z position is set, all ports are opened. Are blocked. Injection / holding pressure switching valve 36
Is also a closed center type electromagnetic directional control valve. When switched to the X position, the screw 3 is pulled backward, so-called suck back, when switched to the Y position, injection or back pressure is applied, and when set to the Z position,
All ports are blocked. On the other hand, the rotation switching valve 37 is a one-way electromagnetic valve, and the hydraulic motor is rotationally driven in a predetermined direction at the Y position, and the oil passage is blocked at the Z position. A pressure control valve, a flow rate control valve or the like for controlling suck back or back pressure at the time of plasticizing may be provided in the pipe line connecting the injection / pressure holding cylinder 4 and the injection / pressure holding switching valve 36. However, it is not shown in FIG.

The first sequence valve 32A is provided with a cartridge 40A, and when the pilot pressure is applied to the poppet chamber 41A, the cartridge 40A is closed and the ports A and B are shut off. Due to the restoring force, the ports A and B are opened. The pilot circuit that applies or releases the pilot pressure to the poppet chamber 41A is configured as follows. That is, the spring-biased first electromagnetic switching valve 42A
And a first shuttle valve 43A having a conventionally known configuration. Then, the first pilot pipe 44A extending from the first communication pipe 31A is connected to the inlet port P of the first electromagnetic switching valve 42A, and its outlet port is connected to one port of the first shuttle valve 43A. It is connected. Therefore, when the electromagnetic coil a of the first electromagnetic switching valve 42A is turned off to take the X position, pilot pressure is applied to the poppet chamber 41A via the first shuttle valve 43A and the cartridge 40A is closed. as a result,
Ports A and B are closed. Further, when the electromagnetic coil a is energized to take the Y position, the first electromagnetic switching valve 42A
The upstream side is closed by the first electromagnetic switching valve 42A, and the first pilot pipe 44A on the downstream side is shut off. Therefore, the poppet room 41A
The pilot oil inside is discharged to the tank T, the cartridge 40A is opened by the restoring force of the spring, and the ports A and B are opened.
The space is open. The pilot pressure in the second communication pipe 31B is applied to the other port of the first shuttle valve 43A via the first auxiliary pilot pipe 45A.

The second sequence valve 32B, the second electromagnetic switching valve 42B, the second shuttle valve 43B, etc. are constructed in the same manner as those of the first one, so that the same reference numeral "A" is used instead. Will be displayed with a "B" added, and duplicate explanation will not be given.

According to the present embodiment, first and second setting devices 50 and 53 and first to third comparators 51, 52 and 54, which are mainly used as a safety device, are provided. First
The output line a of the setter 50 is connected to one input terminal of the first comparator 51, and the other input terminal of the second pressure sensor is provided on the upstream side of the second sequence valve 32B. A signal relating to the pressure detected at 47 is input through the line c. Then, the output signal is input to the second operation command device 24B and the second electromagnetic switching valve 42B through the signal line d. The other output line b of the first setting device 50 is
A signal relating to the pressure detected by the first pressure sensor 46, which is connected to one input terminal of the second comparator 52 and is connected to the other input terminal of the first sequence valve 32A on the upstream side of the first sequence valve 32A. It is designed to be input by e. The output line of the second comparator 52 is the signal line f,
The second electromagnetic switching valve 42A and the first operation command device 24A are connected by g. Second setting device 5
3 and the third comparison value unit 54 has one input terminal on the signal line h, and the other input terminal and the pressure sensor 8 on the signal line j.
Are connected respectively. The output terminal of the second setting device 53 is connected to the signal lines f and g by the signal line k.

Next, the operation of the above embodiment will be described in the following order. "1" Configuration of hydraulic circuit that diverts hydraulic oil (Fig. 2) (a) Rotational drive of screw (a) When screw is abnormal (b) Injection / pressure holding operation (b) Mold opening / closing operation (a) Mold opening / closing operation Rotational operation of the screw with which the "2" hydraulic oil merges (Fig. 3) (b) When the screw has an abnormality (b) Energy-saving operation during the pressure holding process "3" Mold opening / closing operation with the hydraulic oil merged (Fig. 4) (B) When the mold opening / closing is abnormal

Structure of hydraulic circuit for diverting hydraulic oil of "1" (FIG. 2): The electromagnetic coils a of the first and second electromagnetic switching valves 42A and 42B are turned off. Therefore, these first and second electromagnetic switching valves 42A and 42B take the X position, as shown in FIG. The electric motor 20 is started.
Then, the amount of hydraulic oil controlled by the first and second control valves 22A and 22B is changed to the first and second hydraulic pumps 21A and 21A.
21B sucks it up from the tank T, pressurizes it, and discharges it to the first and second discharge pipes 30A, 30B. Since hydraulic pressure is acting on the first communication pipe 31A, the pressure is used as pilot pressure from the first pilot pipe 44A through the first electromagnetic switching valve 42A to the first shuttle valve 4A.
It flows toward 3A and acts on the poppet chamber 41A of the first sequence valve 32A. Therefore, the cartridge 40A
Is closed and the connection between ports A and B is cut off. Similarly, since hydraulic pressure is acting on the second connecting pipe 31B, the pressure flows as pilot pressure from the second pilot pipe 44B to the second shuttle valve 43B, and the second sequence valve 32B. Acts on the poppet chamber 41B. Therefore, the cartridge 40B is closed and the ports A and B are shut off. The hydraulic oil discharged from the first hydraulic pump 21A is
Through the first discharge pipe 30A toward the mold opening / closing switching valve 35,
Then, the hydraulic oil discharged from the second hydraulic pump 21B passes through the second discharge pipe 30B and the injection / pressure-holding switching valve 36.
And is pumped to the rotation switching valve 37. The state in which the hydraulic oil is flowing is shown by a thick solid line in FIG.

Rotational drive of screw "1" (a): As shown in FIG. 2, the injection / pressure-holding switching valve 36 is switched to the Z position. Then, the entire amount flows toward the hydraulic motor 7. The rotation switching valve 37 is switched to the Y position by exciting its electromagnetic coil a. Then, the hydraulic motor 7 rotates and the screw 3 is rotationally driven. The injection material is plasticized and weighed as is well known in the art.

When the screw of (1) (a) (1) is abnormal: The allowable pressure value is set in the first setting device 50.
When the screw 3 bites the injection material, for example, and the rotational load increases, the pressure in the second discharge pipe 30B also increases. The increased pressure is detected by the second pressure sensor 47 and compared with the allowable pressure value set in the first comparator 51. When the allowable pressure value is exceeded, for example, an OFF signal is input to the second operation command device 24B via the signal line d. As a result, the discharge amount of the second hydraulic pump 21B is controlled to, for example, zero, and damage to the screw 3 and the like is prevented. When the allowable pressure value is exceeded, the signal is also applied to the electromagnetic coil a of the second electromagnetic switching valve 42B, but since this signal is a signal that turns off the electromagnetic coil a, there is no problem. Further, it is clear that the abnormally increased pressure can be released by a conventionally known relief valve or the like.

[1] (a) (b) Injection / pressure-holding operation: Even when the screw 3 is rotationally driven and measured, hydraulic oil is supplied to the injection / pressure-holding cylinder 4 to suck. Although it is possible to back the screw 3 or to apply a back pressure to the screw 3, only the injection / holding pressure will be described below. The rotation switching valve 37 is switched to the Z position. Then, the injection / pressure holding switching valve 36 is energized by its electromagnetic coil b and Y
Switch to the position. Then, the second discharge pipe 3
The hydraulic oil in 0B is supplied to the piston head chamber 6 of the injection / pressure-holding cylinder 4. As a result, the screw 3 is driven in the axial direction, and the measured molten resin is injected and filled into the cavities of the molds 11 and 12 in a known manner. Although not shown in FIG. 2, the pressure is controlled by the controller to carry out the pressure holding process.

Mold opening / closing operation of "1" (b): As shown in FIG. 2, since the hydraulic oil discharged by the first hydraulic pump 21A reaches the mold opening / closing switching valve 35, This mold open / close switching valve 35 is turned on by energizing its electromagnetic coil b.
Switch to the position. Then, the hydraulic oil is supplied to the piston rod chamber 15 of the mold opening / closing cylinder 16. As a result, the toggle type mold clamping device 13 is opened. When switched to the X position, the hydraulic oil is supplied to the piston head chamber 14 this time, and the movable mold 12 is clamped with respect to the fixed mold 11 as conventionally known.

When the mold opening / closing of (1) (b) (i) is abnormal: The allowable pressure value is set in the first setting device 50. When an accident such as biting occurs in the mold clamping device 10, the pressure of the hydraulic oil in the first discharge pipe 30A rises, but this pressure is constantly detected by the first pressure sensor 46, and the second comparison Since the detected pressure value exceeds the permissible set pressure value, for example, the OFF signal is input to the signal line g.
Is input to the first operation command device 24A. With this signal, the discharge amount of the first hydraulic pump 21A is controlled to zero, for example. This prevents accidents such as damage to the mold clamping device 10. Even when the mold clamping device 10 is in an abnormal state, it is clear that an abnormal pressure can be released by a conventionally known relief valve or the like. When the detected pressure value exceeds the allowable pressure value, the signal is also applied to the first electromagnetic switching valve 42A, but this signal does not excite the electromagnetic coil a of the first electromagnetic switching valve 42A, which causes a problem. There is no.

Rotation operation of the screw in which the hydraulic oil of "2" merges (FIG. 3): The mold opening / closing switching valve 35 is switched to the Z position. The electromagnetic coil a of the first electromagnetic switching valve 42A is excited by a signal from the control device. Second electromagnetic switching valve 42
The electromagnetic coil a of B is not excited. Then, the first solenoid operated directional control valve 42A is switched to the Y position as shown in FIG. Then, the first and second hydraulic pumps 2
Drive 1A and 21B. Then, the hydraulic oil is discharged from the first and second hydraulic pumps 21A and 21B. The hydraulic oil discharged from the first hydraulic pump 21A is also supplied to the first pilot pipe 44A, but the first pilot pipe 44A on the upstream side of the first electromagnetic switching valve 42A is the first pilot pipe 44A.
The pilot pressure does not act on the poppet chamber 41A because it is closed by the electromagnetic switching valve 42A and the downstream side is opened to the tank T. Therefore, the cartridge 40A of the first sequence valve 32A is opened, and the ports A and B are electrically connected. As a result, the hydraulic oil discharged from the first hydraulic pump 21A passes through the first discharge pipe 30A, the first connecting pipe 31A, the first sequence valve 32A and the second connecting pipe 31B to the second connecting pipe 31B. Join the discharge pipe 30B. Then, the injection / pressure holding switching valve 36 and the rotation switching valve 37 are reached. A state in which the hydraulic oil flows in this manner is shown by a thick solid line in FIG. Hereinafter, as described above,
The combined hydraulic oil is supplied to the hydraulic motor 7 and measured.
Also, it is supplied to the injection / pressure holding cylinder 4 to inject and hold pressure.

When the screw of (2) (2) is abnormal: When the screw 3 bites the injection material, for example, and the pressure rises, the pressure of the hydraulic oil in the first communication pipe 31A also rises.
This increased pressure is then transferred to the auxiliary pilot pipe 45.
Poppet chamber 41 from A via first shuttle valve 43A
Applied to A. As a result, the cartridge 40A is closed and the port A, which is shown in the opened state in FIG.
Between B is cut off. Therefore, backflow of the hydraulic oil does not occur between the first and second hydraulic pumps 21A and 21B. This solves the problem of breakage of the first and second hydraulic pumps 21A and 21B due to backflow of hydraulic oil. Furthermore, according to the present embodiment, the first and second connecting pipes 31A and 31B are provided with the first and second pressure sensors 46 and 47, respectively, so that the first setting device 50 has an allowable pressure. If a value is set, the pressure values detected by the first and second pressure sensors 46 and 47 and the allowable pressure value will be the first and second comparators 51 and 52.
When the detected pressure value exceeds the set pressure value, for example, an OFF signal is applied from these comparators 51 and 52 to the electromagnetic coil a of the first and second electromagnetic switching valves 42A and 42B.
These first and second electromagnetic switching valves 42A and 42B are switched to the X position. In addition, the first and second operation command devices 2
4A and 24B are also applied to the first and second hydraulic pumps 21.
The discharge amounts of A and 21B are controlled to zero. As described above, according to the present embodiment, double safety is achieved.

Energy-saving operation during the pressure-holding process of (2) (b): In FIG. 3, the rotation switching valve 37 is switched to the Z position. Then, the injection / holding pressure switching valve 36 is set to the Y position. Then, the combined hydraulic oils are supplied to the piston head chamber 6 of the injection / pressure holding cylinder 4 as described above. This enables high-speed injection. At this time,
The pressure at the pressure holding step is set in the second setting device 53.
The pressure in the piston head chamber 6 of the injection / pressure-holding cylinder 4 is detected by the pressure sensor 8 and input to the third comparator 54. In the third comparator 54, the set pressure value and the detected pressure value are compared, and when the detected pressure value exceeds the set pressure value, that is, when the pressure at the pressure holding step is reached, the OFF signal is output by the signal line k. It is applied to the electromagnetic coil a of the first electromagnetic switching valve 42A to turn it off. When turned off, the pilot pressure acts on the poppet chamber 41A as described above. The ports A and B are shut off, and the hydraulic oil is supplied only from the second hydraulic pump 21B. At the same time, the signal is applied to the first operation command device 24A, and the first hydraulic pump 21A is zero-controlled in pressure and flow rate. As a result, energy saving operation is performed.

Mold opening / closing operation in which the hydraulic oil "3" merges: FIG. The injection / pressure-holding switching valve 36 and the rotation switching valve 37 are switched to the Z position by the control device. Further, the electromagnetic coil a of the second electromagnetic switching valve 42B is energized to the Y position. The first electromagnetic switching valve 42A remains off. Then, the electric motor 20 starts the first and second hydraulic pumps 21A and 21B. Then, the hydraulic oil is discharged from the first and second hydraulic pumps 21A and 21B to the first and second discharge pipes 30A and 30B and the first and second communication pipes 31A and 31B. The hydraulic oil discharged from the second hydraulic pump 21B is also supplied to the second pilot pipe 44B,
Since the upstream side of the second pilot pipe 44B is closed by the second electromagnetic switching valve 42B and the downstream side thereof is opened to the tank T, the pilot pressure does not act on the poppet chamber 41B. Therefore, the cartridge 40B of the second sequence valve 32B is opened and the ports A and B are electrically connected. As a result, the hydraulic oil discharged from the second hydraulic pump 21B is supplied to the second discharge pipe 30B and the second communication pipe 31.
B, second sequence valve 32B and first connecting pipe 31
It merges with the first discharge pipe 30A through A. And then
The mold open / close switching valve 35 is reached. The state in which the hydraulic oil flows is shown by a thick solid line in FIG. The mold open / close switching valve 35 is switched to the Y or X position to open / close the mold as described above. At this time, it is clear that the molds are opened and closed at high speed.

[3] (3) Abnormal mold opening / closing: When the toggle type mold clamping device 13 cannot be opened / closed for some reason and a high load is generated, the first discharge of the first hydraulic pump 21A is performed. The pressure in the pipe 31A also rises, and the pressure in the first communication pipe 31A also rises. The increased pressure is applied to the poppet chamber 41B from the second auxiliary pilot pipe 45B via the second shuttle valve 43B. As a result, although shown in the opened state in FIG. 4, the cartridge 40B is closed and the ports A and B are shut off from each other. Therefore, backflow of the hydraulic oil is prevented between the first and second hydraulic pumps 21A and 21B,
Damage to the first and second hydraulic pumps 21A and 21B is prevented. Further, according to the present embodiment, the first and second connecting pipes 31A and 31B have the first and second pressure sensors 46 and 4 respectively.
7 are provided respectively, therefore, if the allowable pressure value is set in the first setter 50, the first and second pressure sensors 4
The pressures detected at 6 and 47 and the allowable pressure value are compared by the first and second comparators 51 and 52, and when the detected pressure value exceeds the set allowable pressure value, the comparators 51 and 52 turn off, for example. The signal is applied to the first and second electromagnetic switching valves 42A and 42B. These first and second electromagnetic switching valves 42A, 42B
Switches to the X position. Further, the discharge amounts and pressures of the first and second hydraulic pumps 21A and 21B, which are applied to the first and second operation command devices 24A and 24B, are zero-controlled.
This prevents damage to the mold apparatus 10.

Although the ejector device for ejecting a molded product and the drive device for slidably driving the injection device are not shown in the above embodiment, it is obvious that these devices can be driven by hydraulic actuators. Is. When the biasing directions of the springs of the first and second electromagnetic switching valves 42A and 42B are changed to bias the electromagnetic coil a,
It is also clear that it can be implemented to take the X position. Furthermore, the first and second electromagnetic switching valves 42A, 42B,
It is also clear that the first and second sequence valves 32A, 32B etc. are not limited to the illustrated embodiment.

[0036]

As described above, according to the first aspect of the present invention, a plurality of mechanically coupled variable displacement hydraulic pumps are driven by an electric motor, and at that time, each of the hydraulic pumps is driven. A plurality of operations for supplying the discharged working oil to each of the plurality of actuators, and a combination of the working oil discharged from each of the hydraulic pumps into a unidirectional flow to select a selected actuator of the plurality of actuators. It is easy to use because it can be operated independently. Moreover, in the single operation, the hydraulic oil discharged from the hydraulic pumps is combined with the flow in the other direction and supplied to another selected actuator of the plurality of actuators. Also, the effect of being able to efficiently supply the amount of hydraulic oil according to the purpose to the actuators having different capacities is further obtained.
In addition, since a variable displacement type hydraulic pump is applied to the hydraulic pump, unloading valve, flow rate adjusting valve, etc. are unnecessary,
This also has the effect of simplifying the circuit configuration of the hydraulic control device and reducing the cost. According to the second aspect of the present invention, when an excessive load is generated during the single operation, the circuit that joins the hydraulic oil discharged from the plurality of hydraulic pumps is shut off, so that the overload occurs during the single operation. Also, backflow of hydraulic oil does not occur between multiple hydraulic pumps. Therefore, an accident that damages the hydraulic pump can be prevented. Claim 3
According to the invention described in (3), when an excessive load that exceeds the set pressure value is generated during the single operation, the circuit that joins the hydraulic oil discharged from the plurality of hydraulic pumps is cut off, and the control of each hydraulic pump is performed. Since the pressure is set to zero, it is possible to prevent the backflow of the hydraulic oil and avoid the wasteful discharge of the hydraulic oil. According to the invention described in claim 4, when the holding pressure process is performed by the injection / holding cylinder during the single operation, when the holding pressure value measured by the injection / holding cylinder reaches the set pressure value, a plurality of units are set. Since the discharge amount of a predetermined hydraulic pump of this hydraulic pump is set to zero, energy saving molding can be performed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a hydraulic control device for an injection molding machine according to the present invention.

FIG. 2 is a schematic diagram showing a flow state of hydraulic oil during a combined operation in the embodiment of the hydraulic control device for the injection molding machine according to the present invention.

FIG. 3 is a schematic diagram showing a flow state of hydraulic oil during an independent operation in the embodiment of the hydraulic control device for the injection molding machine according to the present invention.

FIG. 4 is a schematic diagram showing a flow state of hydraulic oil during another independent operation in the embodiment of the hydraulic control device for the injection molding machine according to the present invention.

FIG. 5 is a schematic view showing a hydraulic control device of a conventional injection molding machine.

[Explanation of symbols]

1 injection device 3 screw 4 injection / pressure-holding cylinder 7 hydraulic motor 8 pressure sensor 10 mold clamping device 16 mold opening / closing cylinder 20 electric motors 21A, 21B variable displacement type first and second hydraulic pumps 24A, 24B Operation command devices 30A and 30B First and second discharge pipes 31A and 31B First and second connecting pipes 32A and 32B First and second sequence valves 43A and 43B First and second shuttle valves 46 and 47 First and second Pressure sensor 50, 53 first and second setting device

[Procedure amendment]

[Submission date] March 29, 2002 (2002.3.2)
9)

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kiyohide Gari             1-6-1, Funakoshi-minami, Aki-ku, Hiroshima-shi, Hiroshima               Japan Steel Works, Ltd. (72) Inventor Akihiro Maehara             1-6-1, Funakoshi-minami, Aki-ku, Hiroshima-shi, Hiroshima               Japan Steel Works, Ltd. (72) Inventor Kazuyuki Kihara             2-16-46 Minami Kamata, Ota-ku, Tokyo Stocks             Company Tokimec F term (reference) 3H089 AA72 AA74 BB01 BB15 BB16                       CC01 CC08 CC11 DA03 DA07                       DA14 DB03 DB06 DB37 DB46                       DB48 DB49 EE17 EE31 FF07                       GG02 JJ05                 4F206 AP02 AR02 JA07 JD03 JM05                       JN06 JN21 JT02 JT23 JT24

Claims (8)

[Claims] 1. A plurality of variable displacement hydraulic pumps mechanically coupled to each other are driven by an electric motor, and hydraulic oil discharged from each hydraulic pump at that time is supplied to each of a plurality of actuators. By combining a plurality of operations and the hydraulic oil discharged from each of the hydraulic pumps into a unidirectional flow,
A hydraulic control method for appropriately performing a single operation of supplying the selected actuator to the plurality of actuators, wherein the single operation includes operating oil discharged from each of the hydraulic pumps in a flow in another direction. A hydraulic control method for an injection molding machine, characterized by including another independent operation of merging and supplying the plurality of actuators to another selected actuator. 2. The hydraulic control method according to claim 1, wherein
A hydraulic control method for an injection molding machine, wherein a circuit for joining hydraulic oil discharged from a plurality of hydraulic pumps is cut off when an excessive load is generated during a single operation. 3. The hydraulic control method according to claim 1, wherein
When an excessive load exceeding the set pressure value is generated during independent operation, the circuit that joins the hydraulic oil discharged from multiple hydraulic pumps is shut off, and the control pressure of each hydraulic pump is set to zero. Hydraulic control method for molding machine. 4. A plurality of mechanically coupled variable displacement hydraulic pumps are driven by an electric motor, at which time hydraulic oil discharged from each hydraulic pump is supplied to each of a plurality of actuators. By combining a plurality of operations and the hydraulic oil discharged from each of the hydraulic pumps into a unidirectional flow,
A hydraulic control method for appropriately performing a single operation of supplying a selected injection / pressure-holding cylinder of the plurality of actuators, wherein a pressure-holding step is performed by the injection / pressure-holding cylinder during the single operation, When the holding pressure value measured by the injection / holding cylinder reaches a set pressure value, the discharge amount of a predetermined hydraulic pump of the plurality of hydraulic pumps is set to zero. Method. 5. A plurality of variable displacement hydraulic pumps that are mechanically coupled and driven, and a plurality of control valves, wherein a plurality of hydraulic oils are discharged from the plurality of hydraulic pumps. A hydraulic control device adapted to be supplied to an actuator, wherein each discharge pipe of the plurality of hydraulic pumps is connected to a predetermined actuator of the plurality of actuators, and the discharge pipe is , On the upstream side of the actuator, connected to each other by a communication pipe in which the plurality of control valves are interposed, and when a predetermined control valve of the control valve is energized, one of the discharge pipes is discharged. When the pipe communicates with the other discharge pipe through the communication pipe and the other predetermined control valve of the control valve is energized,
The hydraulic control device for an injection molding machine, wherein the other discharge pipe of the discharge pipes communicates with the one discharge pipe via the communication pipe. 6. The hydraulic control device according to claim 5,
A hydraulic control device for an injection molding machine in which the control valve shuts off the connecting pipe when an excessive load is applied to the discharge pipe. 7. The hydraulic control device according to claim 5,
The discharge pipe is provided with a pressure sensor, and when an excessive load is generated in the discharge pipe, the connecting pipe is shut off by the control valve, and when the detected pressure value detected by the pressure sensor exceeds the set pressure value, A hydraulic control device for an injection molding machine in which the control pressure of the hydraulic pump is controlled to zero. 8. A plurality of variable displacement hydraulic pumps, which are mechanically coupled and driven, and a plurality of control valves, wherein a plurality of hydraulic oil is discharged from the plurality of hydraulic pumps. A hydraulic control device adapted to be supplied to an actuator, wherein each discharge pipe of the plurality of hydraulic pumps has a predetermined actuator of the plurality of actuators and a selected one of the plurality of actuators. The discharge pipe is connected to an injection / pressure-holding cylinder, and the discharge pipe is connected to each other via a communication pipe in which the plurality of control valves are interposed on the upstream side of the actuator. When the control valve is activated, one discharge pipe connected to the predetermined actuator is connected to the other discharge pipe connected to the injection / pressure-holding cylinder via the communication pipe. When the holding pressure value communicating with the pipe and detected by the pressure sensor provided in the injection / pressure holding cylinder reaches the set pressure value, the predetermined hydraulic pump of the hydraulic pump sets the discharge amount to zero. A hydraulic control device for an injection molding machine, wherein the hydraulic control device is controlled as follows.