JP2014141024A - Injection molding machine and injection molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding machine and an injection molding method capable of controlling a plurality of fluid pressure actuators to make the actuators operate precisely with small energy.SOLUTION: A fixed capacity pump 30 driven by a rotational speed controllable drive motor 32 and a variable capacity pump 31 driven by a rotational speed controllable drive motor 35 are provided as pumps for supplying working fluid, the drive motor 32 of the fixed capacity pump 30 is controlled to ON when operating at least a mold clamping cylinder 150 and the drive motor 32 of the fixed capacity pump 30 is controlled to OFF when not operating the cylinder. Further, the drive motor 35 of the variable capacity pump 31 is constantly driven, and the variable capacity pump 31 is controlled so as to discharge working fluid at a plurality of steps of set pressure.

Description

  The present invention relates to an injection molding machine and an injection molding method. More specifically, the present invention has a plurality of pumps for discharging a working fluid to operate each of a plurality of fluid pressure actuators. In order to operate the fluid pressure actuator, an injection molding machine controlled to supply the working fluid from one or more of the pumps to the predetermined fluid pressure actuator, and the working fluid is discharged by the pump. The present invention relates to an injection molding method for supplying and operating a predetermined fluid pressure actuator among a plurality of fluid pressure actuators.

  As shown in FIG. 1, an injection molding machine is generally closed as a fluid pressure actuator that operates when a working fluid such as pressure oil (hereinafter referred to as pressure oil) is supplied from a pump. A clamping cylinder that clamps the mold with a predetermined force and opens the mold after the molding material has solidified, an ejector cylinder that ejects the molded product from the mold, and an injection device Some include a shift cylinder for moving the nozzle so that the nozzle is touched and spaced apart, and a core block moving cylinder for moving the core block of the mold. Some injection molding machines further include a half nut cylinder for moving the half nut in order to engage and release the movable platen and the clamping cylinder. These actuators not only differ in operation timing depending on the process, but also differ in the flow rate and pressure of pressure oil. For this reason, as a pump in a conventional general injection molding machine, a pump having a size corresponding to the maximum flow rate or pressure of pressure oil has been selected from among actuators.

  However, such a selection inevitably results in a relatively large pump. Since this relatively large pump is expensive, the manufacturing cost of the injection molding machine is increased. Also, the drive motor for driving the pump is generally operated at all times, and when the fluid pressure actuator is inactive or the fluid pressure actuator to be operated requires only a relatively small flow rate or pressure of pressure oil, Since a large amount of pressure oil discharged from the pump is unloaded to the tank by a relief valve or the like, energy loss occurs in the drive motor for driving the pump. Therefore, for example, as described in Patent Document 1, there is known an injection molding machine including a plurality of pumps for operating each fluid pressure actuator.

  Patent Document 1 includes a plurality of hydraulic pumps and a hydraulic oil supply circuit that joins or individually supplies hydraulic oils discharged from the plurality of hydraulic pumps to selected hydraulic actuators of the plurality of hydraulic actuators. An injection molding machine including a hydraulic drive unit is disclosed.

Patent Document 1 further describes
-The plurality of hydraulic pumps should use the same rated hydraulic pumps or different rated hydraulic pumps,
A plurality of the hydraulic pumps are configured as a pump unit integrated by a pump support base;
The hydraulic pump uses a variable discharge hydraulic pump capable of setting a plurality of fixed discharge flow rates by changing the swash plate angle.The drive motor uses a servo motor connected to a servo circuit.
The hydraulic oil supply circuit includes a merging circuit for merging and supplying hydraulic oil discharged from the hydraulic pumps to the hydraulic actuator;
An injection molding machine is disclosed, wherein the hydraulic oil supply circuit includes one or more switching valves that individually supply hydraulic oil discharged from the hydraulic pumps to the hydraulic actuator. Yes.

  In Patent Document 1, the pressure oil discharged from both hydraulic pumps 2vp and 2vq is merged and supplied to each actuator, and the pressure oil discharged from either hydraulic pump 2vp or 2vq is supplied to a predetermined actuator. Thus, it is described that the hydraulic pump 2vq that is not used is in a stopped state (0032, 0033, 0036).

  Further, in Patent Document 1, the discharge flow rates of the hydraulic pumps 2vp and 2vq are set to a plurality of fixed discharge flow rates Qo and Qs, and the other fixed discharge flow rate Qs is set larger than one fixed discharge flow rate Qo serving as a reference. By setting a plurality of operation modes combining a plurality of operation steps and a plurality of fixed discharge flow rates Qo, and selecting the operation mode at the time of molding, the discharge flow rates of the hydraulic pumps 2vp and 2vq It is described that it is possible to switch to a fixed discharge flow rate Qo... Corresponding to the process (0022, 0043, 0044). Patent Document 1 states that “the use of the hydraulic pumps 2vp... Capable of setting at least two fixed discharge flow rates Qo and Qs further subdivides the substantial capacity of the hydraulic pumps 2vp. Therefore, in combination with the use of the two hydraulic pumps 2vp and 2vq, matching and controllability can be further improved, and the fixed discharge flow rate Qo can be set by changing the swash plate angle Rs. Since the settable variable discharge hydraulic pumps 2vp... Are used, two fixed discharge flow rates Qo... Can be easily and reliably obtained ”(0049).

  And in patent document 1, if the servomotors 3p and 3q are provided as drive motors for driving the hydraulic pumps 2vp and 2vq, and the rotational speeds of the servomotors 3p and 3q are variably controlled, each hydraulic pump It is described that the discharge flow rate and the discharge pressure of 2 vp and 2 vq can be respectively changed (0021, 0023).

JP 2007-69501 A

  However, in the said patent document 1, the servomotor is employ | adopted as the drive motor of each variable displacement pump. Such servo motors are generally relatively expensive. Therefore, the invention described in Patent Document 1 has a problem that the manufacturing cost of the injection molding machine increases.

  In Patent Document 1, a plurality of fixed discharge flow rates Qo and Qs are set for a plurality of variable displacement pumps, respectively. That is, in Patent Document 1, the operation of each fluid pressure actuator is controlled based on the flow rate of the working fluid discharged from a predetermined variable displacement pump. However, as a fluid pressure actuator in an injection molding machine, particularly in a mold clamping cylinder, pressure for supplying a working fluid to the mold clamping cylinder is an important element in order to accurately control the mold clamping force. In particular, even when another fluid pressure actuator is operated in parallel with the mold clamping cylinder, the pressure of the working fluid supplied to the other fluid pressure actuator decreases as the working fluid is supplied to the mold clamping cylinder. In such a case, the operation of the other fluid pressure actuator cannot be accurately controlled.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an injection molding machine and an injection molding method capable of controlling a plurality of fluid pressure actuators to operate accurately with less energy. .

In order to achieve the above object, the invention according to claim 1 has a plurality of pumps for discharging a working fluid to respectively operate a plurality of fluid pressure actuators, and among the fluid pressure actuators, An injection molding machine controlled to supply the working fluid from one or more of the pumps to the predetermined fluid pressure actuator to operate the predetermined fluid pressure actuator; A constant displacement pump driven by a drive motor capable of controlling the rotational speed; and a variable displacement pump driven by a drive motor capable of controlling the rotational speed, wherein the constant displacement pump is a predetermined one of the plurality of fluid pressure actuators. When the fluid pressure actuator is operated, the drive motor is driven. When the fluid pressure actuator is not operated, the drive motor is driven. The variable displacement pump is controlled to be driven at a low rotational speed or to be stopped. The variable displacement pump is operated at a set pressure of a plurality of stages according to each process while the drive motor is constantly driven. It is controlled to be discharged.
In order to achieve the above object, the invention according to claim 2 is the invention according to claim 1, wherein the variable displacement pump comprises an axial piston pump having a swash plate capable of changing an inclination angle. Cut-off control for reducing the inclination angle of the swash plate is performed before the pressure at which the working fluid is discharged reaches a set pressure.
In order to achieve the above object, the invention according to claim 3 is a closed loop control according to claim 1 or 2, wherein the working fluid is supplied from the variable displacement pump. The pressure control valve which performs is provided.
In order to achieve the above object, the invention according to claim 4 is the invention according to any one of claims 2 and 3, wherein the pressure of the working fluid, the inclination angle of the swash plate are preset. The constant displacement pump drive motor is operated or stopped at a minimum rotational speed in conjunction with at least one of the timing, mold clamping force, and movable platen position.
In order to achieve the above object, the invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the drive motor of the variable displacement pump is inverter-controlled. In addition, after the working fluid is raised to the target pressure, or at a preset timing, it is controlled so as to reduce the rotation speed.
In order to achieve the above object, the invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the fluid pressure actuator includes a clamping cylinder. It is characterized by comprising a pipe line that joins the working fluid discharged from the constant displacement pump and the variable displacement pump and supplies it to the clamping cylinder.
In order to achieve the above object, the invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein a plurality of the constant capacity pumps are provided for a single drive motor. It is connected, It is comprised so that a working fluid can be supplied to a predetermined | prescribed fluid pressure cylinder from arbitrary said constant capacity pumps.
In order to achieve the above object, the invention according to claim 8 is an injection molding in which a working fluid is discharged by a pump and supplied to a predetermined fluid pressure actuator among a plurality of fluid pressure actuators. In the method, a constant displacement pump driven by a drive motor capable of controlling the rotational speed and a variable displacement pump driven by a drive motor capable of controlling the rotational speed are provided as the pump, and the plurality of fluid pressure actuators The constant displacement pump drive motor is driven when the predetermined fluid pressure actuator is operated, and the constant displacement pump drive motor is driven at the minimum rotational speed or the drive is stopped when the fluid pressure actuator is not operated. Control, always drive the drive motor of the variable displacement pump, and discharge the working fluid at multiple stages of set pressure It is characterized in that for controlling the variable displacement pump so as to.

According to the first aspect of the present invention, when a predetermined fluid pressure actuator that needs to be supplied with a working fluid at a maximum flow rate among a plurality of fluid pressure actuators is operated, the drive motor of the constant capacity pump is driven, The variable displacement pump is driven at a relatively high predetermined rotational speed, and the variable displacement pump is controlled to discharge the working fluid at a relatively high set pressure. Thus, the working fluid can be supplied to the predetermined fluid pressure actuator at the maximum flow rate, and therefore, the predetermined fluid pressure actuator can be appropriately operated with high accuracy. Further, when the predetermined fluid pressure actuator is inoperative, control is performed so that the drive motor of the constant capacity pump is driven at the minimum rotational speed or the drive is stopped. On the other hand, when operating another actuator that supplies a working fluid in a relatively small amount, only the drive motor of the variable displacement pump is driven at a relatively low predetermined rotational speed. As a result, the working fluid can be supplied to the other fluid pressure actuator at an appropriate flow rate or pressure. Therefore, the other fluid pressure actuator can be accurately and appropriately operated without causing energy loss.
According to a second aspect of the invention, in the first aspect of the invention, the variable displacement pump is an axial piston pump having a swash plate whose inclination angle can be changed, and the pressure at which the working fluid is discharged is a set pressure. By adopting a configuration in which cut-off control is performed to reduce the inclination angle of the swash plate before reaching, the inclination of the swash plate is completed before the fluid pressure actuator completes its operation and the working fluid pressure reaches the set pressure. Cut-off control is performed to reduce the angle. This cut-off control is performed before the discharge pressure of the working fluid by the variable displacement pump reaches each set pressure. Therefore, the load on the drive motor of the variable displacement pump is reduced, and as a result, it is possible to prevent energy loss from occurring in the drive motor of the variable displacement pump, and it is possible to accurately control the operation of the fluid pressure actuator. .
According to a third aspect of the present invention, in the first or second aspect of the present invention, a pressure control valve that performs closed loop control is provided in a pipe line to which a working fluid is supplied from the variable displacement pump. Accordingly, the working fluid can be supplied from the variable displacement pump to the predetermined fluid pressure actuator at a more accurate set pressure, and therefore the operation of the fluid pressure actuator can be controlled with high accuracy.
According to the invention of claim 4, in the invention of claim 2 or 3, the pressure of the working fluid, the inclination angle of the swash plate, the preset timing, the mold clamping force, and the movable platen By interlocking with at least one of the positions, it detects when the fluid pressure actuator that needs to be supplied with the working fluid at the maximum pressure is not operating, and operates or stops the constant displacement pump drive motor at the minimum rotational speed. Therefore, it is possible to reliably prevent energy loss from occurring in the drive motor of the constant displacement pump.
According to the invention of claim 5, in the invention of any one of claims 1 to 4, the drive motor of the variable displacement pump is inverter-controlled, so that the working fluid is boosted to the target pressure. It is possible to prevent energy loss from occurring by controlling the rotation speed of the drive motor of the variable displacement pump to be surely reduced after or at a preset timing.
According to the invention of claim 6, in the invention of any one of claims 1 to 5, a mold clamping cylinder which needs to be supplied with a working fluid at a maximum pressure is included in the fluid pressure actuator. Even in this case, the working fluid discharged from the constant displacement pump and the variable displacement pump is merged to supply a large amount of working fluid to the clamping cylinder in a short time so that the clamping cylinder can be moved at high speed. Can be operated.
According to the invention of claim 7, in the invention of any one of claims 1 to 6, a plurality of constant capacity pumps are connected to a single drive motor and By being configured to be able to supply the working fluid to a predetermined fluid pressure cylinder, the flow rate of the working fluid discharged by the constant capacity pump is adjusted according to the number of fluid pressure actuators and the amount of operation thereof. Therefore, the operation of the fluid pressure actuator can be accurately controlled.
According to the invention of claim 8, when operating a predetermined fluid pressure actuator that needs to be supplied with the working fluid at the maximum pressure among the plurality of fluid pressure actuators, the drive motor of the constant capacity pump is driven. In addition, the variable displacement pump is controlled so that the drive motor of the variable displacement pump is driven at a relatively high predetermined rotational speed and the working fluid is discharged at a relatively high set pressure. As a result, the working fluid can be supplied to the predetermined fluid pressure actuator at the maximum pressure, and thus the predetermined fluid pressure actuator can be appropriately operated with high accuracy. Further, when the predetermined fluid pressure actuator is not operated, control is performed so that the drive motor of the constant displacement pump is driven at the minimum rotational speed or the drive is stopped. On the other hand, when operating another actuator that supplies the working fluid at a relatively low pressure, only the drive motor of the variable displacement pump is driven at a relatively low predetermined rotational speed, and the working fluid is driven at a relatively low set pressure. The variable displacement pump is controlled so as to discharge the gas. As a result, the working fluid can be supplied to other fluid pressure actuators at an appropriate pressure, and therefore, the other fluid pressure actuators can be accurately and appropriately operated without causing energy loss.

It is the block diagram shown notionally in order to demonstrate one Embodiment of the injection molding machine by this invention. It is the block diagram shown notionally in order to demonstrate embodiment different from FIG. 1 of the injection molding machine by this invention. It is the figure shown in order to demonstrate the driving | running state of the constant displacement pump and the variable displacement pump in each process of the injection molding machine by this invention. It is the graph shown in order to demonstrate the relationship between the pressure and flow volume of a working fluid by cutoff control before a variable displacement pump reaches | attains each setting pressure. It is the graph shown in order to demonstrate the relationship between the pressure and flow volume of the working fluid discharged by the constant capacity pump and variable capacity pump at the time of mold clamping. It is the graph shown in order to demonstrate the relationship between the command value and flow volume of the working fluid discharged by the constant capacity pump and variable capacity pump at the time of a powerful type opening. It is the graph shown in order to demonstrate the relationship between the pressure and flow volume of the working fluid discharged with a variable capacity pump when moving a half nut. It is the graph shown in order to demonstrate the relationship between the command value of the working fluid discharged with a constant capacity pump when ejecting a molded article with an ejector, and flow volume.

  First, an embodiment of an injection molding machine according to the present invention will be described in detail with reference to FIG. 1 and FIG. In the drawings, the same reference numerals denote the same or corresponding parts.

  The injection molding machine of the present invention generally includes a mold clamping device 1, an injection device 2, a working fluid supply device 3, and a control device 4. The mold clamping device 1 is a mold opening / closing means for opening and closing the molds 10 and 12 by moving the movable platen 13 to which the movable die 12 is attached to the fixed platen 11 to which the fixed die 10 is attached. 14, mold clamping means 15 for clamping and closing the molds 10 and 12 with a predetermined force, and a half nut means 16 for coupling and releasing the movable platen 13 and the mold clamping means 15. The injection molding machine is also provided with ejector means 17 for projecting the molded product from the movable mold 12 after the mold is opened. The injection device 2 includes a screw rotating unit 22 that rotates a screw 21 fitted in the heating cylinder 20 around an axis, an injection unit 23 that moves the screw 21 forward and backward, and a nozzle with respect to the fixed mold 10. Shifting means 24 for moving the heating cylinder 20 so as to be touched and separated is provided.

  The movable platen 13 is supported so as to be movable toward and away from the fixed platen 11. The mold opening / closing means 14 includes a motor 140 provided on the fixed platen 11, a ball screw shaft 141 coupled to the rotation shaft of the motor 140, and a ball screw nut 142 provided on the movable platen 13 and screwed onto the ball screw shaft 141. And a ball screw mechanism 143. The mold clamping means 15 includes a mold clamping cylinder 150 formed in the fixed platen 11, a piston 151 fitted in the mold clamping cylinder 150, and an engagement shaft extending from the piston 151 toward the movable platen. The half nut means 16 is provided on the movable platen 13 and can be engaged with and released from the tie bar 152, and the half nut 160 is engaged with the tie bar 152. And a half nut cylinder 161 that is moved so as to be engaged and released. A through hole 130 through which the tie bar 152 can be inserted is formed at a position corresponding to the engagement shaft 152 of the movable platen 13, and is a surface opposite to the fixed platen 11 of the movable platen 13 and around the through hole 130. The half nut means 16 is disposed on the left side. In this embodiment, four mold clamping means 15 are provided, and each mold clamping cylinder 150 is formed at a corner of the stationary platen 11. The through holes 130 are formed at the corners of the movable platen 13 so as to correspond to the tie bars 152 of the mold clamping unit 15. A plurality of annular engagement grooves 152 a are formed on the peripheral surface of the tip portion of the tie bar 152, and an engagement protrusion 160 a that can be engaged with the engagement groove 152 a of the engagement shaft 152 is formed on the inner surface of the half nut 160. Is formed. The half nut cylinder 161 engages the engagement protrusion 160a of the half nut 160 with the engagement groove 152a of the tie bar 152 by extension driving, and the half nut 160 from the engagement groove 152a of the tie bar 152 by retraction driving. The engagement protrusion 160a is separated to release the engagement so that the movable platen 13 can move in the axial direction of the tie bar 152. The engagement protrusion 160a is coupled to the piston 162 inserted in the half nut cylinder 161. A half nut 160 is provided at the tip of the rod 163. By engaging the engagement protrusion 160a of the half nut 160 with the engagement groove 152a of the tie bar 152, the movable platen 13 and the mold clamping means 15 are coupled, and the molds 10 and 12 are moved by the mold clamping means 15. It is possible to perform mold clamping and perform strong mold opening at the time of mold release. On the other hand, when the engagement of the engagement protrusion 160a of the half nut 160 is released from the engagement groove 152a of the tie bar 152, the coupling between the movable platen 13 and the mold clamping means 15 is released and the mold opening / closing means 14 is movable. The plate 13 can be opened and closed by moving the plate 13 relative to the fixed plate 11 at a relatively high speed. The ejector means 17 includes an ejector pin 170 provided in the movable mold 12 so as to be able to advance and retreat, an ejector plate 171 to which a base end portion of the ejector pin 170 is connected, and an ejector rod 172 whose tip is joined to the ejector plate 171. And an ejector cylinder 174 into which a piston 173 coupled to the ejector rod 172 is fitted.

  On the other hand, the heating cylinder 20 of the injection device 2 is supported by a housing plate 25, and the injection device 2 including the housing plate 25 is supported so as to be capable of shifting in the axial direction with respect to the stationary platen 11. In this embodiment, a shift cylinder 240 is provided on the housing plate 25 as the shift means 24, and a rod 242 coupled to a piston 241 fitted into the shift cylinder 240 is coupled to the stationary platen 11. . The rear end (right end in FIGS. 1 and 2) of the screw 21 fitted in the heating cylinder 20 is joined to the intermediate plate 26 via a screw connector, and the intermediate plate 26 is relative to the housing plate 25. It is supported so that it can move close and far away. The screw rotating means 22 in this embodiment includes a motor 220 that is provided on the intermediate plate 26 and that rotates the screw 21 around its axis, and a belt or chain that is wound between the rear end of the screw 21 and the motor 220. It is comprised with the winding transmission means 221, such as. Further, a back plate 27 is disposed on the rear side of the intermediate plate 26, and the rear end of the screw 21 is joined between the intermediate plate 26 and the back plate 27 as the injection means 23 in this embodiment. A ball screw mechanism 28 is provided for moving the intermediate plate 26 so as to be separated (advanced) / adjacent (retracted) from the back plate 27. The ball screw shaft 280 of the ball screw mechanism 28 is driven to rotate about the axis. A motor 281 for this purpose is provided on the back plate 27.

  Here, the plurality of fluid pressure actuators according to the present invention include the mold clamping cylinder 150 and the piston 151 of the mold clamping means 15 and the half nut cylinder 161 and the piston 162 of the half nut means 16 and the ejector means in the embodiment described above. 17 ejector cylinders 174 and pistons 173, and shift cylinders 240 and pistons 241 of the shift means 24. Pressure oil is used as a working fluid supplied to these fluid pressure actuators. In the embodiment described above, the ball screw mechanism 28 that constitutes the driving source of the mold opening / closing means 14 that moves the movable plate 13 relative to the fixed plate 11 at a relatively high speed and the injection means 23 that moves the screw 21 in the axial direction. In the above description, the electric motors 140, 281, and 220 are used as the driving source of the screw and the screw rotating means 22 for driving the screw 21 to rotate about the shaft. Thus, an oil motor that rotates by supplying a working fluid can be employed, and a hydraulically operated cylinder can be employed instead of the ball screw mechanism. However, in particular, by adopting a servo motor or the like as the electric motors 140 and 281 and combining them with the ball screw mechanisms 143 and 28, the mold opening / closing speed, the mold opening / closing stop position, and the forward speed of the screw 21 ( It is possible to control the injection speed) and the stop position of the axial movement with high accuracy.

  The working fluid supply device 3 includes a constant capacity pump 30 and a variable capacity pump 31. In this embodiment, a servo motor 32 is employed as a drive motor of the constant capacity pump 30 and is controlled to be turned on / off based on a drive signal output from the control device 4 as described later. The rotation direction and the rotation speed (the number of rotations per unit time) are controlled by the servo amplifier 33, and the pressure oil can be discharged at a predetermined flow rate and pressure according to the control. When OFF, the rotation of the servo motor 32 may not only be stopped completely, but may be driven to rotate at the minimum rotation speed that does not apply a load to the constant capacity pump 30 and the servo motor 32. As the constant capacity pump 30, a vane pump, a gear pump, a piston pump, or the like that has a simple structure and is relatively inexpensive can be employed.

Further, in this embodiment, a plurality of constant capacity pumps (two in the embodiment shown in FIGS. 1 and 2) 30A and 30B are connected to a single servo motor 32, and one constant capacity pump is provided. A pipe 51 having a check valve 50 is connected to the pump 30A, and a pipe having a relief valve 52 branches between the constant capacity pump 30A of the pipe 51 and the check valve 50. Is provided. The pipe 55 connected to the other constant capacity pump 30B is provided by branching a pipe having a relief valve 56. Further, the pipelines 51 and 55 are connected via a 2-port 2-position switching valve 57. In the embodiment shown in FIG. 1, when the servo motor 32 is turned ON, if the 2-port 2-position switching valve 57 is controlled to be closed, the pressure oil discharged from the constant-capacity pump 30A passes through a merging unit 70 described later. The pressure oil discharged from the constant displacement pump 30B can flow only to the ejector cylinder 174. When the 2-port 2-position switching valve 57 is controlled to be in the open state, the pressure oil discharged from the constant capacity pump 30A and the pressure oil discharged from the constant capacity pump 30B are merged, and a merging section 70 described later is joined. It flows into the clamping cylinder 150. Therefore, in the embodiment shown in FIG. 1, the pressure oil can be appropriately supplied to the mold clamping cylinder 150 and the ejector cylinder 174. As a result, the mold clamping and the powerful mold opening and the removal of the molded product are performed respectively. It can be controlled appropriately and accurately.
On the other hand, in the embodiment shown in FIG. 2, when the 2-port 2-position switching valve 57 is controlled to be closed when the servo motor 32 is turned on, the pressure oil discharged from the constant capacity pump 30A will be described later. It is possible to flow into the mold clamping cylinder 150 via the merging portion 70, and the pressure oil discharged from the constant capacity pump 30B can be unloaded to the tank 34 by the relief valve 56. When the 2-port 2-position switching valve 57 is controlled to be in the open state, the pressure oil discharged from the constant capacity pump 30A and the pressure oil discharged from the constant capacity pump 30B are merged, and are connected via a merge section 60 described later. It becomes possible to flow into the mold clamping cylinder 150. Therefore, in the embodiment shown in FIG. 2, the pressure oil can be appropriately supplied to the mold clamping cylinder 150, and as a result, the mold clamping and the strong mold opening can be controlled appropriately and accurately, respectively.

  On the other hand, the drive motor 35 of the variable displacement pump 31 is connected to an inverter 36 and is always driven to rotate based on a drive signal output from the control device 4 as will be described later. It can be rotated at a rotational speed of. This rotational speed can be changed by sequence control set for each process. As the variable displacement pump 31, an axial piston pump is adopted. The axial piston pump 31 includes a swash plate 37 that can change the inclination angle, a discharge pressure changing cylinder 38 that changes the inclination angle of the swash plate 37, and a plurality of pressure oil set pressures by the variable displacement pump 31. A throttle switching valve 39 for controlling the operation of the discharge pressure change cylinder 38 in order to switch the stage to two stages, for example, a low pressure side (8.0 MPa as an example) and a high pressure side (18.8 MPa as an example); An inclination angle adjusting unit 43 including relief valves 40 and 41 connected to the switching valve 39 and a switching valve 42 connected to both relief valves 40 and 41 is provided. The pipe 44 connected to the discharge port of the axial piston pump 31 is provided with a filter 45, and the pipe 44 is provided with a branch portion 46. As will be described later, the axial piston pump 31 performs an inclination angle adjusting unit 43 so as to perform cut-off control for reducing the inclination angle of the swash plate 37 before the pressure oil discharged by the axial piston pump 31 reaches a set pressure. Is controlled by the control device 4. A pipe 91 having a reducing valve 90 is connected between the branching portion 46 and the merging portion 70.

  Pipe lines 64 and 65 having cartridge valves 60 and 61 and 4-port 2-position switching valves 62 and 63 are connected to the oil chambers on the mold clamping side and the strong mold opening side on both sides of the mold clamping cylinder 150, respectively. A pipe having two-port two-position switching valves 66 and 67 is connected to branch from the cartridge valves 60 and 61 of the pipes 64 and 65 and the clamping cylinder 150 to form a drain circuit. . Both the four-port two-position switching valves 62 and 63 and the two-port two-position switching valves 66 and 67 are supplied with pressure oil to one of the mold clamping cylinders 150 when the mold is clamped and when the strong mold is opened. It is controlled to operate in conjunction so that the pressure oil is discharged. Furthermore, a pressure sensor 68 for detecting the pressure of the supplied pressure oil is provided in the pipe line 64 to which pressure oil is supplied when the mold clamping cylinder 150 is clamped. A signal output cable 69 of the pressure sensor 68 is connected to the control device 4. The pipes 64 and 65 having the cartridge valves 60 and 61 and the 4-port 2-position switching valves 62 and 63 supply pressure oil to the clamping cylinder 150 from the constant displacement pump 30 and the variable displacement pump 31 as described above. Is connected to a junction 70.

  A pipe 71 connected to both ends of the half nut cylinder 161 is provided with a four-port three-position switching valve 72. A pipe 73 for supplying a pressure flow to the four-port three-position switching valve 72 is provided in the pipe 73. A pressure reducing valve 74 is provided. Similar to the half nut cylinder 161, the shift cylinder 240 is also provided with a 4 port 3 position switching valve 77 in a pipe line 76 connected to both ends, and supplies pressure oil to the 4 port 3 position switching valve 77. A pressure reducing valve 79 is provided in the pipe line 78 for this purpose. The pipe 73 of the half nut cylinder 161 and the pipe 78 of the shift cylinder 240 are connected to the branch portion 46 of the variable displacement pump 31 together with the pipes 64 and 65 of the clamping cylinder 150.

  In the embodiment shown in FIG. 1, similarly to the half nut cylinder 161 and the shift cylinder 240, the 4-port 3-position switching valve 81 is provided in the pipe line 80 connected to the oil chambers on both sides of the ejector cylinder 174. The pipe 82 connected to the four-port three-position switching valve 81 joins the pipe 55 connected to the constant capacity pump 30B and is connected to the two-port two-position switching valve 57. A pipe 83 where the pipe 51 having the check valve 50 connected to the constant capacity pump 30 </ b> A and the two-port two-position switching valve 57 merge is connected to the junction 70.

  Therefore, in the embodiment shown in FIG. 1, the hydraulic fluid is supplied to the half nut cylinder 161, the shift cylinder 240, and the mold clamping cylinder 150 among the fluid pressure actuators by the variable displacement pump 31. Further, pressure oil is supplied to the mold clamping cylinder 150 by the constant displacement pumps 30 </ b> A and 30 </ b> B together with the variable displacement pump 31. That is, when performing mold clamping and powerful mold opening, the pressure oil discharged by both the constant displacement pump 30 and the variable displacement pump 31 can be merged and supplied to the mold clamping cylinder 150. Further, pressure oil is supplied to the ejector cylinder 174 from the constant displacement pumps 30A and 30B.

  On the other hand, in the embodiment shown in FIG. 2, the pipes 80 connected to the oil chambers on both sides of the ejector cylinder 174 are replaced with the 4-port 3-position switching valve 81 shown in FIG. A flow control valve (hereinafter simply referred to as a flow control valve) 84 having a direction switching function that is closed-controlled is provided, and a pressure reducing valve 86 is provided in a pipe line 85 connected to the flow control valve 84. ing. In the embodiment shown in FIG. 2, the pipe 85 of the ejector cylinder 174 includes the pipes 64 and 65 of the clamping cylinder 150, the pipe 73 of the half nut cylinder 161, and the pipe of the shift cylinder 240. 78 is connected to the branching portion 46 of the variable displacement pump 31.

  Therefore, in the embodiment shown in FIG. 2, the hydraulic fluid is supplied to the half nut cylinder 161, the shift cylinder 240, the ejector cylinder 174, and the mold clamping cylinder 150 by the variable displacement pump 31. To do. Further, pressure oil is supplied to the mold clamping cylinder 150 by the constant displacement pumps 30 </ b> A and 30 </ b> B together with the variable displacement pump 31. That is, in the embodiment shown in FIG. 2, as in the embodiment shown in FIG. 1, when the mold clamping and the strong mold opening are performed, the discharge is performed by both the constant capacity pump 30 and the variable capacity pump 31. Can be supplied to both the oil chambers of the clamping cylinder 150.

  Next, the operation and control of the injection molding method of the present invention depending on the case of using the injection molding machine configured as in the embodiment shown in FIGS. 1 and 2 with reference to FIGS. This will be described together with the contents of control by the apparatus. 1 and 2 will be described individually for each configuration, and the common configuration will be described without particularly mentioning which embodiment it is. And

  The injection molding method of the present invention generally includes a predetermined fluid pressure actuator among a plurality of fluid pressure actuators (in the above-described embodiment, mold clamping cylinder 150, half nut cylinder 161, ejector cylinder 174, shift cylinder 240). The injection molding method is to supply a working fluid to the pump, and as a pump for supplying the working fluid, a constant capacity pump 30 driven by a drive motor 32 capable of controlling the rotational speed, and a drive capable of controlling the rotational speed. A variable displacement pump 31 driven by a motor 35 is provided to operate a predetermined fluid pressure actuator (clamping cylinder 150) (a working fluid needs to be supplied at a maximum flow rate) among a plurality of fluid pressure actuators. Sometimes the drive motor 32 of the constant capacity pump 30 is driven and this fluid pressure actuator (clamping cylinder 50), the drive motor 32 of the constant capacity pump 30 is controlled to be driven at the minimum rotational speed or stopped, and the drive motor 35 of the variable capacity pump 31 is constantly (at a predetermined rotational speed). The variable displacement pump 31 is controlled so as to drive and discharge the working fluid at a plurality of stages of set pressure.

  When performing injection molding, as shown in FIG. 3, as a process on the mold clamping side, mold closing including mold closing, pressure increasing and holding, pressure release, strong mold opening (release), mold opening, and taking out are performed. The steps are performed sequentially. Further, the engagement of the half nut 160 with the tie bar 152 is performed between the mold closing and the mold clamping, and the half nut 160 is released from the engagement with the tie bar 152 between the strong mold opening and the mold opening. Is called. On the other hand, in the injection-side process, molding material injection / filling (including holding pressure) and weighing are performed in correspondence with the mold-clamping-side process.

  In the mold closing process, the ball screw shaft 141 of the ball screw mechanism 143 constituting the mold opening / closing means 14 is rotationally driven around the axis by the electric motor 140, and the movable platen 13 is moved close to the fixed platen 11 to move the movable platen 13 relative to the fixed die 10. The movable mold 12 is abutted and the mold is closed. At this time, the tip of the engagement shaft 152 of the mold clamping unit 15 is inserted into the through hole 130 of the movable platen 13. At that time, in the variable displacement pump 31, the set pressure of the working fluid is controlled to the low pressure side (8 MPa in this embodiment) by the control device 4 as shown in FIG. Since it is not necessary, the rotational speed of the drive motor is reduced by inverter control to such an extent that the pilot pipe pressure can be maintained. At this time, the servo motor 32 of the constant capacity pump 30 is not outputting a drive signal and is in an OFF state.

  When the mold closing is completed, the control device 4 outputs a drive signal for expanding the half nut cylinder 161 to the 4-port 3-position switching valve 72, engages the half nut 160 with the tie bar 152, and moves the movable platen 13. Is combined with the mold clamping means 15. Here, as shown in FIG. 7, the variable-capacity pump 31 set at the low pressure side (8 MPa) is used to expand the half nut cylinder 161 at a constant flow rate through the 4-port 3-position switching valve 72. Pressure oil from the relief valve 40 is supplied to the side cylinder chamber to increase the pressure, and before the pressure of the discharged pressure oil reaches a set pressure (8 MPa), for example, from around 7 MPa which is about 1 MPa less than 8 MPa. Due to this leakage, the discharge pressure changing cylinder 38 is actuated so that the inclination angle of the swash plate 37 of the variable displacement pump 31 is reduced, and the cutoff control is started. Then, the flow rate of the pressure oil discharged per rotation of the variable capacity pump 31 is reduced and brought close to the set pressure, and then maintained at the set pressure. At this time, the servo motor 32 of the constant capacity pump 30 does not output a drive signal, and is in an OFF state (stopped or fixed to the constant capacity pump 30 and its servo motor 32 in preparation for a mold clamping process described later. (Slow speed operation at the lowest rotation speed at which no load is applied).

  When the coupling between the movable platen 13 and the mold clamping means 15 is completed, a mold clamping process is performed. The mold clamping process includes a pressure increasing process and a holding process. In the mold clamping process, it is necessary to supply pressure oil to the mold clamping cylinder 150 at the maximum flow rate. In the variable displacement pump 31, the set pressure is changed to the high pressure side (18.8 MPa in this embodiment) by switching the switching valve 42 of the tilt angle adjusting unit 43 to connect the relief valve 41 and the throttle switching valve 39. In addition, since it is necessary to relatively increase the flow rate of the pressure oil, the rotational speed of the drive motor 35 is sequence-controlled to the maximum rotational speed through at least the mold clamping process by the control of the inverter 36. The servo motor 32 of the constant capacity pump 30 is rotated at the maximum rotation speed by a signal output from the control device 4, and both constant capacity pumps 30 </ b> A and 30 </ b> B are driven by the servo motor 32. Then, the 2-port 2-position switching valve 57 is operated to be in the open position to connect the pipes 51, 55, and the 4-port 3-position switching valve 81 is in the closed position (and shown in FIG. 2). In the embodiment, the flow rate control valve 84 connected to the ejector cylinder 174 is in the neutral position (closed position), and the pressure oil discharged from both the constant capacity pumps 30A and 30B is formed via the junction 70. Supplied to the clamping cylinder 150. At the same time, the pressure oil discharged from the variable displacement pump 31 set on the high pressure side is supplied from the branch portion 46 through the reducing valve 90 to the mold clamping cylinder 150 through the junction portion 70. . Further, the control device 4 supplies the cartridge valves 60 and 61 and the 4-port 2-position switching valve 62 so as to supply the pressure oil to the oil chamber (the left side in FIGS. 1 and 2) of the mold clamping cylinder 150. , 63 are interlocked and controlled. Therefore, the pressure oil discharged from the constant displacement pumps 30A and 30B and the variable displacement pump 31, respectively, merges at the merge portion 70 and is supplied to the oil chamber on the mold clamping side of the mold clamping cylinder 150, and the tie bar 152 and the half nut 160 are supplied. In a state in which the movable platen 13 is coupled, the movable platen 13 is pulled toward the fixed platen 11 side, and the molds 10 and 12 that have been closed are pressure-clamped with a predetermined force. At this time, the pressure of the pressure oil supplied to the mold clamping side of the mold clamping cylinder 150 is detected by the pressure sensor 68 and input to the control device 4. The control device 4 monitors the pressure of the pressure oil detected by the pressure sensor 68, and as shown in FIG. 5, before the pressure oil reaches the set pressure (18.8 MPa), for example, 1 MPa before the set pressure. When the pressure is reached, the servo motor 32 of the constant capacity pump 30 is turned off or is controlled to rotate at the minimum rotational speed. In the present invention, not only the pressure oil pressure detected by the pressure sensor 68 but also the inclination angle of the swash plate 37, the mold clamping force by the mold clamping means 15, and the movable platen 13 (or the fixed mold 12). As a result of detecting the position, either the timing set in advance in a sequential manner or a combination thereof is linked with the combination so that the servomotor 32 of the constant-capacity pump 30 is OFF-controlled before the pressure oil is below the set pressure. Good. When the constant displacement pump 30 is stopped, the 2-port 2-position switching valve 57 is also closed. As shown in FIG. 5, the pressure oil discharged from the constant displacement pump 30 and supplied to the mold clamping cylinder 150 is held in a state where the pressure has increased to a set value at a constant flow rate from the ON to the OFF. . In addition, the discharge of the tilt angle adjusting unit 43 is performed so that the tilt angle of the swash plate 37 is reduced by the leak of the pressure oil from the relief valve 41 from the vicinity where the pressure oil pressure is about 1 MPa before the set pressure. The pressure changing cylinder 38 is actuated to start cut-off control. In the holding process, the drive motor 35 is kept rotating at a high speed, and the pressure oil discharged from the variable displacement pump 31 and supplied to the mold clamping cylinder 150 becomes very small after being cut off from a constant flow rate. The pressure is maintained in an elevated state. In the holding step, the pressure of the pressure oil supplied to the mold clamping cylinder 150 at the time of mold clamping after the constant capacity pump 30 is stopped is provided in the pipeline 91 between the branching portion 46 and the merge portion 70. It can be accurately controlled by the reducing valve 90.

  On the other hand, in the process on the injection side, in parallel with the mold clamping process, as shown in FIG. The four-port three-position switching valve 77 is switched and the shift cylinder 240 is driven to extend, and the heating cylinder 20 supported by the housing plate 25 is advanced to operate so as to stand by by touching the fixed mold 10 with a nozzle. The nozzle touch may be always performed. In addition, in the injection device 2 after the previous injection, the screw 21 is rotationally driven around the axis by the motor 220 provided on the intermediate plate 26 constituting the screw rotating means 22, and is molded into the heating cylinder 20 from the hopper. The material is kneaded and heated and melted and stored in front of the screw 21 in the heating cylinder 20 (metering step). In the measuring step, the screw 21 moves back in the axial direction in the heating cylinder 20 in order to store a predetermined amount of the molding material kneaded and melted in front of the screw 21 in the heating cylinder 20. Therefore, in response to the retraction of the screw 21, the motor 281 of the injection means 23 provided on the back plate 27 drives the ball screw mechanism 28 connected to the intermediate plate 26 to move the intermediate plate 26 backward.

Then, the ball screw mechanism 28 connected to the intermediate plate 26 is driven by the motor 281 of the injection means 23 provided on the back plate 27, and the screw 21 abutted on the intermediate plate 26 is axially moved in the heating cylinder 20. As shown in FIG. 3, the molding material is injected (filled) and injected (holding pressure) into the cavities in the molds 10 and 12 by being moved forward. When the molding material heated and melted is filled into the cavities in the molds 10 and 12 by injection, cooling is started. When the injection is finished, the injection device 2 rotates the screw 21 around the axis in the heating cylinder 20 by the screw rotating means 22 for the next injection, and the heating cylinder of the molding material melted by being kneaded and heated. In 20, storage ahead of the screw 21 is started. Further, if necessary, the four-port three-position switching valve 77 is operated so as to extend the shift cylinder 240, the heating cylinder 20 supported by the housing plate 25 is moved backward, and the nozzle is separated from the fixed mold 10. Let At this time, the operation of the shift cylinder 240 is performed by the control device 4 by the variable displacement pump 31 via the 4-port 3 position switching valve 77 as shown in FIG. Oil is supplied to the extension side cylinder chamber of the shift cylinder 240 at a constant flow rate. The variable displacement pump 31 performs cutoff control so that the discharge pressure changing cylinder 38 is operated so as to reduce the inclination angle of the swash plate 37 before the pressure of the discharged pressure oil reaches the set pressure, and per pump rotation. While reducing the flow rate of the pressure oil discharged, gradually approaches the set pressure and maintains the set pressure. At this time, the servo motor 32 of the constant displacement pump 30 is not outputting a drive signal and can be turned off.

  When cooling is completed and solidified after the molding material is injected and filled in the cavity, the control device 4 operates to open the reducing valve 90 and opens the 2-port 2-position switching valve 66 constituting the drain circuit. The depressurizing step is performed to release the pressure of the pressure oil that has been operated and supplied to the mold clamping side of the mold clamping cylinder 150. At this time, the variable displacement pump 31 can change the set pressure to the low pressure side in the pressure release process, but it can be maintained at the high pressure side and the rotational speed of the drive motor 35 can be controlled to a low speed by the inverter 36. Good. In addition, the rotational speed of the drive motor 35 of the variable displacement pump 31 in the depressurization process may be controlled to decrease from a high speed to a low speed when it takes a relatively long time to complete the depressurization process. Since it is necessary to control at a high speed in the strong mold opening process immediately after this depressurization process, when the depressurization process can be completed in a relatively short time, the rotational speed is increased from the time of mold clamping to the strong mold opening process. Can be maintained. In addition, the servo motor 32 of the constant capacity pump 30 can be started to rotate at a relatively low rotation in preparation for the next powerful mold opening process.

  When the depressurization process is completed, a strong mold opening process for releasing is performed. Specifically, the control device 4 controls the servo motor 32 of the constant capacity pump 30 that has been started to rotate at a relatively low rotation to be in an ON state so as to rotate at a high speed. Further, when the set pressure of the variable displacement pump 31 is changed to the low pressure side in the pressure releasing process, the inclination angle of the swash plate 37 of the variable displacement pump 31 is increased by the operation of the discharge pressure changing cylinder 38 of the inclination angle adjusting unit 43. Then, control is performed so that the set pressure is returned to the high pressure side. Further, when the set pressure of the variable displacement pump 31 is kept on the high pressure side in the pressure release process, the set pressure on the high pressure side is maintained. Therefore, the variable displacement pump 31 is driven so as to discharge the pressure oil at a maximum (fixed) flow rate until reaching the set pressure on the high pressure side. Then, the cartridge valves 60, 61 and the 4-port 2-position switching valves 62, 63 are controlled in conjunction so that pressure oil is supplied to the release side (right side in FIGS. 1 and 2) of the mold clamping cylinder 150. At this time, as in the mold clamping process, the pressure oil discharged from the constant displacement pump 30 and the variable displacement pump 31 merges at the merge section 70 and is supplied to the oil chamber on the mold opening side of the mold clamping cylinder 150. . Therefore, the movable platen 13 in a state where the tie bar 152 and the half nut 160 are coupled is separated from the fixed platen 11 side, and the molds 10 and 12 in a state where the molded product is adhered are opened with a predetermined force. . Here, in the powerful mold opening process, the moving speed of the piston 151 of the mold clamping cylinder 150 in the mold opening direction is controlled. This speed control can be performed by controlling the rotation speed of the servo motor 32 of the constant capacity pump 30. Then, the pressure oil discharged by the constant capacity pump 30 is changed to a command value as shown in FIG. When the pressure oil discharged from the constant capacity pump 30 reaches the set pressure, the pressure oil is leaked from the relief valve 66. On the other hand, the variable displacement pump 31 has one command value, and a fixed amount of oil is discharged corresponding to the command value, and the swash plate 37 immediately before the pressure oil reaches the set pressure (for example, about 1 MPa). Cut-off control is performed so as to reduce the inclination angle.

  When the molding material in the cavity is compressed from a position where the molds 10 and 12 are slightly opened, both the constant capacity pump 30 and the variable capacity pump 31 are operated during the injection filling process of the molding material to clamp the mold. Pressure oil is supplied to the mold clamping side of the cylinder 150. The servo motor 32 of the constant capacity pump 30 can be controlled to be OFF at the timing when the cooling starts, and the pressure oil can be supplied only by the variable capacity pump 31. In the case of injection compression molding, although not shown, an accumulator can be provided separately, and pressure oil can also be supplied from this accumulator to the clamping cylinder 150 during injection compression.

  When the powerful mold opening process is completed, the control device 4 operates the 4-port 3-position switching valve 72 to retract the half nut cylinder 161, release the engagement of the half nut 160 with respect to the tie bar 152, and move the movable platen 13. Separated from the mold clamping means 15. Here, as shown in FIG. 7, the variable-capacity pump 31 set at the low pressure side (8 MPa) is used to expand the half nut cylinder 161 at a constant flow rate through the 4-port 3-position switching valve 72. Discharge so that the inclination angle of the swash plate 37 of the variable displacement pump 31 is reduced before the pressure oil is supplied to the side cylinder chamber and reaches a set pressure (8 MPa) (for example, from about 1 MPa before 8 MPa). The pressure changing cylinder 38 is controlled and cut off. At this time, the servo motor 32 of the constant capacity pump 30 does not output a drive signal and is in an OFF state (stopped or loaded in the constant capacity pump and its servo motor in preparation for the mold clamping process described later. It is considered to be a slow speed operation at a minimum rotation speed that does not take.

  When the engagement of the half nut 160 is released, the ball screw shaft 141 of the ball screw mechanism 143 is rotationally driven around the axis by the electric motor 140, and the movable platen 13 is moved away from the fixed platen 11. The movable mold 12 is opened. At this time, the through hole 130 of the movable platen 13 comes out of the tip of the tie bar 152 of the mold clamping means 15. In this mold opening process, as shown in FIG. 3, the variable displacement pump 31 has the working fluid set pressure controlled to the low pressure side (8 MPa in this embodiment), and almost no flow rate of pressure oil is required. Therefore, the rotational speed of the drive motor 35 is reduced by the control of the inverter 36 to such an extent that the pilot pressure can be maintained. At this time, the servo motor 32 of the constant capacity pump 30 is not outputting a drive signal and is in an OFF state.

  When the mold opening is completed, in the case of the embodiment shown in FIG. 1, as shown in FIG. 3, the controller 4 causes the servo motor 32 of the constant capacity pump 30B to rotate slightly at the same time as the mold opening is completed. And then the rotational speed is controlled to be high for the operation of the ejector means 17. Then, the control device 4 controls the 4-port 3-position switching valve 81 so as to extend the ejector cylinder 174 with the 2-port 2-position switching valve 57 closed. Thereby, in FIG. 1, pressure oil is supplied to the extension side cylinder chamber of the ejector cylinder 174 only by the constant displacement pump 30B.

  In the case of the embodiment shown in FIG. 2, the servo motor OFF state when the mold is opened in FIG. Then, the flow control valve 84 is controlled to extend the ejector cylinder 174. As a result, the pressure oil discharged from the variable displacement pump 31 driven by the drive motor 35 in the state where the set pressure is the low pressure side (8 MPa) and the rotational speed is high is stored in the extension side cylinder chamber of the ejector cylinder 174. Will be supplied.

  In the embodiment described above, in addition to the fluid pressure pumps 30 and 31, the ball screw mechanism 143 is driven by the electric motor 140 of the mold opening / closing means 14 in the mold opening / closing process, and by the electric motor 281 of the injection means 23 in the injection process. Since the ball screw mechanism 28 is driven, each process can be performed with high accuracy. In the present invention, the constant displacement pump 30 and the variable displacement pump 31 are used as the pumps for supplying the working fluid to the fluid pressure actuators. Can be supplied appropriately. In addition, since the variable displacement pump 31 is cut off before reaching the set pressure, the pressure of the working fluid can be accurately controlled with less energy. Since the variable displacement pump 31 can be controlled to discharge the working fluid at a plurality of set pressures, it is possible to accurately supply the working fluid with an appropriate pressure with a small amount of energy according to the fluid pressure actuator to be operated. it can.

  The constant displacement pump 30 controls the servo motor 32 to be ON only when operating the fluid pressure actuator (the mold clamping cylinder 150) that needs to be supplied with the working fluid at the maximum flow rate among the plurality of fluid pressure actuators. Since the servomotor 32 is OFF-controlled when the fluid pressure actuator is not operated, noise generated by the motor can be reduced, temperature rise of the working fluid can be suppressed, and injection molding can be performed with less energy. Further, a plurality of constant capacity pumps 30A, 30B... Are used as the constant capacity pump 30, and these constant capacity pumps 30A, 30B... Are connected to a single drive motor to supply a working fluid. Since the working fluid can be supplied by one or both of the constant capacity pumps 30A and 30B according to the fluid pressure actuator to be operated, the working fluid having an appropriate pressure with less energy can be accurately supplied to the fluid pressure actuator. Can be supplied.

  The present invention can be applied with various modifications within the scope of the gist of the present invention.

  1: mold clamping device, 2: injection device, 3: working fluid supply device, 4: control device, 14: mold opening / closing means, 15: mold clamping means, 16: half nut means, 17: ejector means, 24: shift means 30: constant displacement pump, 31: variable displacement pump, 32: servo motor (drive motor for constant displacement pump), 35: drive motor for variable displacement pump, 46: branching section, 68: pressure sensor, 70: junction section, 150: Clamping cylinder, 161: Half nut cylinder, 174: Ejector cylinder, 240: Shift cylinder

Claims (8)

A plurality of pumps for discharging a working fluid in order to operate each of the plurality of fluid pressure actuators; and in order to operate a predetermined fluid pressure actuator among the fluid pressure actuators, An injection molding machine controlled to supply the working fluid from one or more of the pumps,
The pump includes a constant capacity pump driven by a drive motor capable of controlling the rotational speed, and a variable capacity pump driven by a drive motor capable of controlling the rotational speed,
The constant capacity pump is driven by a drive motor when a predetermined fluid pressure actuator of the plurality of fluid pressure actuators is operated, and is driven at a minimum rotational speed when the fluid pressure actuator is not operated. Or controlled to stop driving,
The variable displacement pump is controlled to discharge the working fluid at a set pressure in a plurality of stages in a state where the drive motor is always driven.   The variable displacement pump is an axial piston pump having a swash plate whose tilt angle can be changed. Cut-off control is performed to reduce the tilt angle of the swash plate before the pressure for discharging the working fluid reaches a set pressure. The injection molding machine according to claim 1, wherein   The injection molding machine according to claim 1, wherein a pressure control valve that performs closed loop control is provided in a pipe line to which a working fluid is supplied from the variable displacement pump.   The constant capacity pump drive motor is operated or stopped at the minimum rotational speed in conjunction with at least one of the pressure of the working fluid, the inclination angle of the swash plate, the preset timing, the clamping force, and the position of the movable platen. The injection molding machine according to claim 2, wherein the injection molding machine is used.   The drive motor of the variable displacement pump is controlled by an inverter, and is controlled so as to decrease the rotation speed after increasing the working fluid to the target pressure or at a preset timing. The injection molding machine according to any one of claims 1 to 4. The fluid pressure actuator includes a clamping cylinder,
6. The pipe according to claim 1, further comprising a conduit that joins the working fluid discharged from the constant displacement pump and the variable displacement pump and supplies the fluid to the clamping cylinder. Injection molding machine.   A plurality of the constant capacity pumps are connected to a single drive motor, and the working fluid can be supplied from any of the constant capacity pumps to a predetermined fluid pressure cylinder. The injection molding machine according to any one of claims 1 to 6. An injection molding method in which a working fluid is discharged by a pump and supplied to a predetermined fluid pressure actuator among a plurality of fluid pressure actuators.
As the pump, a constant capacity pump driven by a drive motor capable of controlling the rotational speed and a variable capacity pump driven by a drive motor capable of controlling the rotational speed are provided.
The constant capacity pump drive motor is driven when a predetermined fluid pressure actuator of the plurality of fluid pressure actuators is operated, and the constant capacity pump drive motor is driven at a minimum rotational speed when the fluid pressure actuator is not operated. Or control to stop driving,
An injection molding method, wherein the variable displacement pump is controlled so that the drive motor of the variable displacement pump is always driven and the working fluid is discharged at a plurality of stages of set pressures.

Images