JP2008290343A - Apparatus and method for plasticization transfer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable the improvement of the durability, the reduction of the cost of a plasticization transfer apparatus, and the reduction of the molding cycle. <P>SOLUTION: The plasticization transfer apparatus has a fixed platen 14, a mold unit 11, an injection unit 13, a plasticization transfer cylinder having a first medium containing chamber on the rod side and a second medium containing chamber on the head side, a first medium passage connecting the first medium containing chamber with a reversible pump, a second medium passage connecting the second medium containing chamber with the reversible pump and a pilot check valve arranged between the first and second medium passages and connecting the first medium passage with a medium tank at the initial position where the reversible pump is stopped. As not requiring ball screws for raising and lowering the nozzle touch pressure repeatedly, the durability of plasticization transfer apparatus 22 can be improved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a plasticizing transfer device and a plasticizing transfer method.

  Conventionally, in a molding machine, for example, an injection molding machine, a resin heated and melted in a heating cylinder is injected at a high pressure to fill a cavity space of a mold apparatus, and cooled and solidified in the cavity space. Then, the molded product is taken out.

  The injection molding machine includes a mold device, a mold clamping device, and an injection device. The mold device includes a mold including a fixed mold and a movable mold. The mold clamping device includes a fixed platen, a movable platen, and a mold. A tightening motor, a toggle mechanism and the like are provided. When the mold clamping motor is driven and the ball screw is actuated to move the crosshead forward and backward, the toggle mechanism is actuated to generate thrust and advance and retract the movable platen to close the mold, clamp and open the mold. Is done.

  On the other hand, the injection device includes the heating cylinder for heating and melting the resin supplied from the hopper, and an injection nozzle for injecting the molten resin, and a screw is freely rotatable in the heating cylinder. In addition, it is disposed so as to freely advance and retract. Then, the metering motor is driven during the metering process and the screw is rotated, so that the resin is accumulated in front of the screw, the injection motor is driven during the injection process, the screw is advanced, and the resin is injected from the injection nozzle. To do.

  By the way, plasticization is performed between the injection device and the fixed platen so that the resin does not leak from between the injection nozzle and the mold device in the injection step and the subsequent pressure holding step for maintaining the pressure of the resin. A moving device is provided, the plasticizing moving device moves the injection device, and the injection nozzle is pressed against the mold device to perform nozzle touch. For this purpose, a motor, a ball screw, a spring, etc. are provided. When the motor is driven and the injection device is moved while the spring is contracted by the ball screw, the injection force is generated by the urging force generated as the spring contracts. A force for pressing the nozzle against the mold apparatus, that is, a nozzle touch pressure is generated. At this time, since the pressure of the injected resin, that is, the injection pressure and the pressure of the resin when holding pressure is high, that is, the holding pressure is high, the nozzle touch pressure is set higher than the injection pressure and holding pressure. Is done.

  Here, in the injection process and the pressure holding process, since the mold apparatus is in the mold closed state, the nozzle touch pressure is increased, but the mold apparatus is in the mold open state, such as at the time of weighing process, taking out the molded product, etc. If the nozzle touch pressure is increased, the fixed platen is deformed because the pressing force by the movable mold does not act on the fixed mold. Therefore, when the mold apparatus is in the mold open state, the nozzle touch pressure is lowered to perform depressurization.

  Depending on the molding conditions, the mold device may be opened with the nozzle touched. In that case, when the molded product is taken out, the resin that is not sufficiently solidified in the vicinity of the injection nozzle is molded product. A state in which the yarn is pulled without being cut off is formed, and a yarn drawing phenomenon may occur. Therefore, in order to prevent the yarn drawing phenomenon from occurring, reverse forming is performed.

  In the reverse molding, the injection device is retracted in steps other than the injection step and the pressure holding step, the nozzle touch is released, and the resin in the injection nozzle and the resin in the cavity space of the mold device are forcibly separated. Is done by.

  Thus, when performing molding, it is necessary to repeatedly increase or decrease the nozzle touch pressure, but in the electric plasticizing and moving device, the nozzle touch pressure is repeatedly increased and increased. Since the ball nut is moved back and forth on the ball screw shaft every time it is lowered, the ball screw shaft is greatly worn locally and the durability is lowered.

  In order to increase the nozzle touch pressure, when two ball screws are provided to form a biaxial plasticizing movement device, it is necessary to synchronize the operations of the two ball screws. Becomes complicated, and the cost of the plasticizing transfer device increases.

  Therefore, a hydraulic plasticizing moving device is provided. The plasticizing moving device selectively supplies oil to a plasticizing moving cylinder disposed between the injection device and the mold device, and first and second oil chambers formed in the plasticizing moving cylinder. And a check valve for replenishing the oil in the oil tank to the first and second oil chambers in accordance with the operation of the hydraulic pump (see, for example, Patent Document 1). .

In this case, since it is not necessary to use a ball screw to repeatedly increase or decrease the nozzle touch pressure, the durability of the plasticizing moving device can be improved, and the nozzle touch pressure can be increased. When the two-axis plasticizing moving device is formed in order to increase the height, it is only necessary to provide two plasticizing moving cylinders communicated with each other, and the operations of the plasticizing moving cylinders can be easily synchronized. As a result, the cost of the plasticizing transfer device can be reduced.
JP 2002-113757 A

  However, in the conventional plasticizing moving device, in order to increase or decrease the nozzle touch pressure, it is necessary to actuate the check valve by hydraulic pressure, and the operation of the plasticizing moving device is delayed correspondingly. turn into. As a result, the molding cycle becomes long.

  The present invention solves the problems of the conventional plasticizing transfer device, improves the durability, can reduce the cost, and can shorten the molding cycle and the plasticizing transfer device. It is an object to provide a method for moving a computer.

  For this purpose, in the plasticizing movement apparatus of the present invention, there is provided a fixed platen attached to the frame, a first mold and a second mold, and the first mold is attached to the fixed platen. An injection device provided with an injection nozzle and arranged to be movable back and forth with respect to the frame, a cylinder attached to the injection device, a piston, and a piston rod attached to a fixed part, and a first medium on the rod side The storage chamber includes a plasticizing moving cylinder in which a second medium storage chamber is formed on the head side, a reversible pump, a first medium flow path connecting the first medium storage chamber and the reversible pump, A second medium flow path connecting the second medium storage chamber and the reversible pump; and the first medium disposed between the first and second medium flow paths at an initial position where the reversible pump is stopped. Communicating the flow path with the medium tank And a pilot check valve.

  According to the present invention, in the plasticizing moving device, a fixed platen attached to the frame, and a mold device including first and second molds, and the first mold is attached to the fixed platen. An injection device provided with an injection nozzle and arranged to be movable back and forth with respect to the frame, a cylinder attached to the injection device, a piston, and a piston rod attached to a fixed part, and a first medium on the rod side The storage chamber includes a plasticizing moving cylinder in which a second medium storage chamber is formed on the head side, a reversible pump, a first medium flow path connecting the first medium storage chamber and the reversible pump, A second medium flow path connecting the second medium storage chamber and the reversible pump; and the first medium disposed between the first and second medium flow paths at an initial position where the reversible pump is stopped. A port that connects the flow path and the medium tank. And a lot check valve.

  In this case, since it is not necessary to use a ball screw in order to repeatedly increase or decrease the nozzle touch pressure, it is possible to improve the durability of the plasticizing moving device.

  Moreover, since the plasticizing moving cylinders communicated with each other can be used to increase the nozzle touch pressure, the cost of the plasticizing moving device can be reduced.

  Since the first medium flow path and the medium tank can be selectively communicated only by operating the reversible pump, the hydraulic circuit can be simplified. Therefore, the plasticizing moving device can be reduced in size.

  Furthermore, since the first medium flow path and the medium tank are communicated with each other at the initial position where the reversible pump is stopped, the next process can be performed in a short time. Therefore, the molding cycle can be shortened.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this case, an injection molding machine as a molding machine will be described.

  FIG. 1 is a conceptual diagram showing an injection molding machine according to an embodiment of the present invention, FIG. 2 is a diagram showing a hydraulic circuit of a plasticizing / moving device according to the embodiment of the present invention, and FIG. 3 is the reverse of the embodiment of the present invention. It is a figure which shows the principal part of a stop valve unit.

  The injection molding machine includes a mold device 11, a mold clamping device 12, an injection device 13, and a plasticizing movement device 22. The mold device 11 includes a fixed mold 11a as a first mold, and a second mold. The mold clamping device 12 includes a fixed platen 14 for mounting the fixed mold 11a, a movable platen (not shown) for mounting the movable mold 11b, and a drive for mold clamping. A mold clamping motor (not shown) is provided as a part, and the mold clamping motor 11 is driven by moving the movable platen forward and backward, and moving the movable mold 11b to and away from the fixed mold 11a. Mold closing, mold clamping and mold opening are performed.

  On the other hand, the injection device 13 includes a heating cylinder 16 as a cylinder member that heats and melts a resin as a molding material, an injection nozzle 17 that injects the molten resin, a rotatable inside the heating cylinder 16, and A screw (not shown) as an injection member disposed so as to be able to advance and retreat, a metering motor (not shown) serving as a metering drive unit for storing resin melted in front of the screw by rotating the screw, and a screw By moving forward, an injection motor (not shown) is provided as an injection drive unit for injecting resin in front of the screw from the injection nozzle 17, and the metering motor, injection motor, etc. are arranged in the housing 18. Established.

  The injection device 13 includes a base 19 that supports the casing 18, a linear guide 21 as a support member that supports the base 19 movably with respect to the frame fr, and the like.

  The screw includes a screw body, that is, a screw body and a screw head attached to a front end of the screw body, and a flight is formed in a spiral shape on the outer peripheral surface of the screw body, and the spiral groove is formed by the flight. It is formed.

  When the metering motor is driven and the screw is rotated in the forward direction during the metering step, the pellet-shaped resin dropped from a hopper (not shown) is advanced in the groove of the screw, and is heated and melted. Along with this, the screw is retracted by the pressure of the resin, and the resin is stored in front of the screw head.

  Further, when the injection motor is driven to advance the screw during the injection process, the resin stored in front of the screw head is injected from the injection nozzle 17 and filled into the cavity space of the mold apparatus 11. At this time, a backflow prevention device is disposed around the screw head so that the resin stored in front of the screw head does not flow back.

  By the way, in the injection step and the subsequent pressure holding step for maintaining the pressure of the resin, the injection device 13 and the fixing part, the present implementation are performed so that the resin does not leak between the injection nozzle 17 and the mold device 11. In this embodiment, the plasticizing movement device 22 is disposed between the fixed platen 14, the injection device 13 is moved by the plasticizing movement device 22, and the injection nozzle 17 is pressed against the mold device 11. The nozzle touch is performed.

  Therefore, the plasticizing movement device 22 includes a biaxial cylinder device 20 as a driving unit for plasticizing movement, a hydraulic circuit 23 for driving the cylinder device 20, and a control unit that controls the hydraulic circuit 23. 26. When the injection device 13 is moved by driving the cylinder device 20, a nozzle touch pressure that presses the injection nozzle 17 against the mold device 11 is generated. At this time, since the injection pressure and the holding pressure are high, the nozzle touch pressure is set higher than the injection pressure and the holding pressure.

  The cylinder device 20 includes a master cylinder 27 as a first plasticizing moving cylinder and a slave cylinder 28 as a second plasticizing moving cylinder arranged in parallel with the master cylinder 27. In FIG. 1, for the sake of convenience, the master cylinder 27 and the slave cylinder 28 are shown as one plasticizing moving cylinder. The master cylinder 27 and the slave cylinder 28 include a cylinder 31, a piston 32 slidably disposed in the cylinder 31, a piston rod 33 that passes through the cylinder 31 and connects the piston 32 and the mold clamping device 12. Etc., and the inside of the cylinder 31 is divided by a piston 32, whereby a first oil chamber 35 as a first medium storage chamber is provided on the piston rod 33 side, and a second medium storage chamber is provided on the screw head side. As a result, a second oil chamber 36 is formed.

  When the piston 32 is moved backward (moved toward the second oil chamber 36) by supplying oil as a medium to the first oil chambers 35 of the master cylinder 27 and the slave cylinder 28, the injection device 13 moves forward ( The hydraulic pressure as the medium pressure supplied to the first oil chamber 35 becomes the nozzle touch pressure, and the nozzle touch is performed. Further, when the piston 32 moves forward (moves toward the first oil chamber 35) by supplying oil to each of the second oil chambers 36, the injection device 13 moves backward (moves toward the side away from the fixed platen 14). The nozzle touch is released. Here, since the piston rod 33 passes through the first oil chamber 35, the cross-sectional area of the first oil chamber 35 is smaller than the cross-sectional area of the second oil chamber 36. Therefore, if the oil is supplied to the first oil chamber 35 when the nozzle touch is performed as in the present embodiment, the piston 32 is moved when the oil is supplied into the first oil chamber 35. The nozzle can be moved quickly and the nozzle touch can be performed rapidly.

  In addition, since the cylinder device 20 and the fixed platen 14 are connected by the piston rod 33, even if the nozzle touch pressure is generated and the injection nozzle 17 is pressed against the mold device 11, the fixed platen is fixed by the piston rod 33. A force pulling 14 is generated. Therefore, the stationary platen 14 does not fall down.

  The master cylinder 27 and the slave cylinder 28 are arranged on a diagonal line in the fixed platen 14, the master cylinder 27 is fixed below the front side in FIG. 1, and the slave cylinder 28 is fixed above the back side in FIG. 1. The platen 14 and the injection device 13 are connected. In the master cylinder 27 and the slave cylinder 28, the first oil chambers 35 communicate with each other through the oil passage M-1 as the first communication flow path, and the second oil chambers 36 communicate with each other in the second communication flow. They are connected by an oil passage M-2 as a passage and are driven in synchronization with each other.

  As described above, since the plasticizing moving device 22 is connected by the biaxial cylinder device 20 including the master cylinder 27 and the slave cylinder 28, the nozzle touch pressure can be increased in the plasticizing moving device 22. Further, in the master cylinder 27 and the slave cylinder 28, the nozzle touch pressure can be generated in synchronization with each other, and the nozzle touch pressure is provided on the diagonal line in the fixed platen 14, and is applied to the injection nozzle 17 provided on the diagonal line. Since the nozzle touch pressure is generated, the nozzle touch can be stabilized.

  The hydraulic circuit 23 serves as a hydraulic pressure generation source that generates hydraulic pressure of oil and as a reversible pump, and connects the hydraulic pump 38 and the first oil chamber 35 to each other. Oil path M-3 as a medium flow path and a medium supply path for advance, a hydraulic pump 38 and the second oil chamber 36 are connected to each other as a second medium flow path and for backward movement An oil passage M-4 as a medium supply passage, a check valve unit 39 for connecting the portions p1, p2 close to the hydraulic pump 38 on the oil passage M-3, M-4, and the oil passage M-3 , A safety valve unit 41 as a safety device connecting the parts p3 and p4 on the cylinder device 20 side from the parts p1 and p2 on the M-4, and disposed between the parts p1 and p3 on the oil passage M-3. As a medium pressure holding device and as a switching device On the oil passage M-3, the valve 44 is provided with a pressure sensor 45 as a pressure detector disposed between the part p3 and the cylinder device 20, and a hydraulic tank 46 as a medium tank. The hydraulic pump 38, the check valve unit 39 and the safety valve unit 41 are connected. The control unit 26 controls the hydraulic pump 38, and the switching valve 44 is switched.

  The hydraulic pump 38 includes a pump body 51 and a motor 52 as a drive member. In the present embodiment, a reversible induction motor is used as the motor 52, and the motor 52 is selectively driven in the forward direction and the reverse direction by a signal from the control unit 26. The pump body 51 includes a suction / discharge port 54 on the oil path M-3 side and a suction / discharge port 55 on the oil path M-4 side. When the motor 52 is driven in the forward direction, the pump body 51 starts from the oil path M-4. When the oil sucked through the suction discharge port 55 is discharged to the oil passage M-3 through the suction discharge port 54 and the motor 52 is driven in the reverse direction, the oil passage M-3 passes through the suction discharge port 54. The oil sucked in this way can be discharged to the oil passage M-4 through the suction discharge port 55. Further, the motor 52 is driven in the forward direction, the oil sucked from the hydraulic tank 46 is discharged to the oil passage M-3 through the suction / discharge port 54, and the motor 52 is driven in the reverse direction. The sucked oil can be discharged to the oil passage M-4 through the suction discharge port 55.

  Further, the switching valve 44 takes the A position and the B position in accordance with a signal from the control unit 26, blocks the oil passage M-3 at the A position, and connects the oil passage M-3 at the B position. Since the switching valve 44 has a double check type structure to block the oil passage M-3, it is possible to reliably prevent oil from leaking when placed in the A position. In the present embodiment, the double check type structure of the switching valve 44 is formed by a check ball, but it is not necessarily formed by a check ball.

  The pressure sensor 45 detects the oil pressure in the oil passage M-3 and sends a detection signal to the control unit 26. Since the pressure sensor 45 is disposed in the vicinity of the first oil chamber 35 of the cylinder device 20, the oil pressure detected by the pressure sensor 45 is substantially equal to the oil pressure in the first oil chamber 35. Therefore, the control unit 26 can recognize the oil pressure in the first oil chamber 35 according to the sensor output from the pressure sensor 45 and can recognize the nozzle touch pressure.

  And the said safety valve unit 41 is arrange | positioned on the oil path M-5 as a 3rd medium flow path which connects between site | parts p3 and p4, and the safety valves 56 and 57 as a 1st, 2nd relief valve. The oil passage M-5 and the hydraulic tank 46 are connected between the safety valves 56 and 57. The safety valve 56 is normally closed, and when the oil pressure in the oil passage M-3 and the oil pressure in the first oil chamber 35 rise excessively and become higher than the threshold value Pth1, the safety valve 56 is opened to lower the oil pressure. Further, the safety valve 57 is normally closed, and the oil pressure in the oil passage M-4 and the oil pressure in the second oil chamber 36 are excessively increased, and the threshold value Pth2 (in this embodiment, the threshold value Pth1 and When it is higher, it is released and the hydraulic pressure is lowered.

  The check valve unit 39 is formed by a pilot check valve, and a circulation amount for adjusting the excess or deficiency of the oil circulation amount due to the difference in the cross-sectional areas of the first and second oil chambers 35 and 36. Configure the adjustment circuit. For this purpose, the check valve unit 39 is disposed on an oil passage M-6 as a fourth medium flow path connecting the parts p1 and p2, and the first and second check valves 61, 62, Rod 63 disposed between the first and second check valves 61 and 62, support elements 64 and 65 for supporting the first and second check valves 61 and 62, and the support elements 64 and 65, respectively. And first and second check valves 61 and 62 are provided with springs 66 and 67 as first and second urging members. The first and second check valves 61 and 62 include main body portions 61a and 62a and supported portions 61b and 62b. The oil passage M-6 and the hydraulic tank 46 are connected between the first and second check valves 61 and 62 through an oil passage M-7 as a drain passage.

  A valve body 60 is constituted by the first and second check valves 61 and 62 and the rod 63. The valve body 60 can be integrally formed. However, in the present embodiment, the first check valve 61 and the rod 63 are separately provided for the convenience of assembly, and the second reverse valve 60 is provided. The stop valve 62 and the rod 63 are integrally formed.

  The support elements 64 and 65 include storage chambers 68 and 69, and the first and second check valves 61 and 62 are slidably supported in the storage chambers 68 and 69.

  A spring 66 urges the first check valve 61 toward the second check valve 62 in the storage chamber 68 with a spring load f1 as a first biasing force, and the storage chamber 69 Inside, the spring 67 urges the second check valve 62 toward the first check valve 61 with a spring load f2 as a second urging force. Communication paths 71 and 72 are formed in the first and second check valves 61 and 62 so that the oil passage M-3 and the accommodation chamber 68 communicate with each other and the oil passage M-4 and the accommodation chamber 69 communicate with each other. It is done.

  In the present embodiment, the spring load f2 is larger than the spring load f1, and the valve body 60 is placed at the first position on the spring 66 side in the initial position where the hydraulic pump 38 is not operated. As a result, the oil path M-3 and the oil path M-7 are communicated, and the oil path M-4 and the oil path M-7 are not communicated. Further, when the oil pressure in the oil passage M-4 becomes low due to the change in the oil pressure in the oil passages M-3 and M-4, the valve body 60 is moved to the second position on the spring 67 side against the spring load f2. Placed. As a result, the oil passage M-4 and the oil passage M-7 are communicated, and the oil passage M-3 and the oil passage M-7 are not communicated.

When the valve body 60 is placed at the first position, the oil passage M-4 and the oil passage M-7 are reliably disconnected, and the valve body 60 is placed at the second position. The first check valve 61 and the valve when the valve body 60 is placed in the first position so that the oil passage M-3 and the oil passage M-7 are surely disconnected. When the axial distance from the seat is L, and the stroke of the second check valve 62 (supported portion 62b) in the accommodation chamber 69 is L ′,
L '> L
To be. Similarly, the axial distance between the second check valve 62 and the valve seat when the valve body 60 is placed at the second position is L (not shown), and the first in the housing chamber 68 is set. When the check valve 61 (supported portion 61b) has a stroke L ′ (not shown),
L '> L
To be.

  Next, the operation of the plasticizing moving device 22 will be described.

  First, when the metering process is completed in the injection device 13, the injection process is started, the mold closing is completed in the mold device 11, and the mold clamping is performed, a nozzle touch processing unit (nozzle touch processing) (not shown) of the control unit 26 is illustrated. Part) performs a nozzle touch process, sends a signal to the hydraulic pump 38, drives the motor 52 in the forward direction, sends a signal to the switching valve 44, and places the switching valve 44 in the B position. At this time, with the operation of the hydraulic pump 38, the oil in the oil passage M-4 and the oil in the hydraulic tank 46 are sucked and discharged to the oil passage M-3, and the oil discharged by the hydraulic pump 38 is switched. The oil is supplied to the first oil chamber 35 through the valve 44, and the oil is discharged from the second oil chamber 36 to the oil passage M-4. Along with this, the piston 32 is moved backward, the injection device 13 is moved forward, and the nozzle touch is performed.

  Further, with the operation of the hydraulic pump 38, the oil pressure on the oil passage M-3 side becomes a positive pressure, and the oil pressure on the oil passage M-4 side becomes a negative pressure, so that the valve body 60 is placed in the second position. The oil path M-3 and the oil path M-7 are not communicated, and the oil path M-4 and the oil path M-7 are communicated.

  Incidentally, as described above, since the cross-sectional area of the first oil chamber 35 is smaller than the cross-sectional area of the second oil chamber 36, the amount of oil discharged from the second oil chamber 36 is the first oil chamber 36. More than the amount of oil supplied to chamber 35. In this case, the oil discharged from the second oil chamber 36 is sent to the suction side of the hydraulic pump 38 via the oil passage M-4 and drained to the hydraulic tank 46 via the oil passage M-7. . Accordingly, it is possible to adjust the excess or deficiency of the circulation amount of the oil due to the difference in cross-sectional area between the first and second oil chambers 35 and 36.

  In this way, when the nozzle touch is performed and the oil is continuously supplied to the first oil chamber 35, the oil pressure in the oil passage M-3 increases and the nozzle touch pressure also increases. A nozzle touch holding processing unit (nozzle touch holding unit) (not shown) of the control unit 26 performs nozzle touch holding processing, reads the nozzle touch pressure detected by the pressure sensor 45, and the nozzle touch pressure is equal to the set value. Determine whether or not. When the nozzle touch pressure becomes equal to the set value, the nozzle touch holding processing means completes the nozzle touch, sends a signal to the hydraulic pump 38, stops the motor 52, and sends a signal to the switching valve 44, thereby switching the switching valve. 44 is placed in the A position. As a result, the oil passage M-3 is blocked by the switching valve 44, so that the hydraulic pressure and nozzle touch pressure in the first oil chamber 35 can be maintained.

  In this case, since the switching valve 44 has a double check structure, it is possible to reliably prevent oil from leaking when placed in the A position. Therefore, it is possible to prevent the hydraulic pressure in the first oil chamber 35 and the nozzle touch pressure from being lowered.

  As the hydraulic pump 38 is stopped, the oil in the oil passages M-3 and M-4 is drained to the hydraulic tank 46 via the hydraulic pump 38. As described above, since the spring load f2 is larger than the spring load f1, the valve body 60 is placed at the first position, and the oil path M-3 and the oil path M-7 are communicated. . As a result, the oil in the oil passage M-3 is drained to the hydraulic tank 46 through the oil passage M-7.

  In this manner, the resin is filled in the cavity space while the nozzle touch pressure is maintained at a predetermined value. When the injection process and the pressure holding process are completed, the mold apparatus 11 is opened, the molded product is taken out, and the weighing process is started.

  By the way, in the injection process and the pressure holding process, since the mold apparatus 11 is in the mold closed state, the nozzle touch pressure is increased, but the mold apparatus 11 is opened as in the weighing process, taking out the molded product, etc. When in the state, the pressing force by the movable mold 11b does not act on the fixed mold 11a. Therefore, if the nozzle touch pressure is increased, the fixed platen 14 is deformed. Therefore, when the mold apparatus 11 is in the mold open state, the nozzle touch pressure is set to zero (0) to perform depressurization.

  For this purpose, a decompression processing means (decompression processing unit) (not shown) of the control unit 26 performs a decompression process, sends a signal to the switching valve 44 while the hydraulic pump 38 is stopped, and moves the switching valve 44 to the B position. Put on.

  Along with this, the oil in the first oil chamber 35 is drained to the hydraulic tank 46 via the oil passages M-3 and M-7. At this time, the nozzle touch pressure can be made zero while the nozzle 32 is touched without moving the piston 32, so that the fixed mold 11a is not pushed by the injection nozzle 17. Therefore, it is possible to prevent the fixed platen 14 from being deformed.

  In this case, as the nozzle touch is completed, the hydraulic pump 38 is stopped, and the oil in the oil passages M-3 and M-4 is drained to the hydraulic tank 46 via the hydraulic pump 38. When the processing is started, the valve body 60 is placed in the first position. Therefore, simultaneously with the start of the depressurization process, the oil in the first oil chamber 35 is drained to the hydraulic tank 46 via the oil passages M-3 and M-7. As a result, the nozzle touch pressure can be reduced to zero in a short time, and the depressurization process can be performed.

  By the way, as described above, depending on the molding conditions, the mold device 11 may be opened while the nozzle touch is being performed. In this case, when the molded product is taken out, it is sufficiently solidified in the vicinity of the injection nozzle 17. A state in which the unresined resin is not separated from the molded product and the yarn is pulled may be formed, and a yarn drawing phenomenon may occur. Therefore, in order to prevent the yarn drawing phenomenon from occurring, reverse forming is performed.

  In the reverse molding, the injection device 13 is retracted in steps other than the injection step and the pressure holding step, the nozzle touch is released, and the resin in the injection nozzle 17 and the resin in the cavity space of the mold device 11 are forcibly formed. This is done by separating them.

  Therefore, when the mold apparatus 11 is in the mold open state, such as when a weighing process or a molded product is taken out, and the depressurization is being performed, a retreat processing means (not shown) of the control unit 26 ( The reverse processing section) performs the reverse processing, sends a signal to the hydraulic pump 38 with the switching valve 44 in the B position, and drives the motor 52 in the reverse direction.

  As the hydraulic pump 38 is operated, the oil in the oil passage M-3 and the oil in the hydraulic tank 46 are sucked and discharged to the oil passage M-4. The oil discharged by the hydraulic pump 38 It is supplied to the oil chamber 36. Along with this, the piston 32 is advanced, the injection device 13 is retracted, and the nozzle touch is released.

  At this time, the hydraulic pressure on the oil passage M-4 becomes positive with the operation of the hydraulic pump 38, whereas on the oil passage M-3 side, the depressurization processing is performed until immediately before the reverse processing is started. Therefore, the oil is drained to the hydraulic tank 46. Therefore, the valve body 60 is placed at the first position, and the oil passage M-3 and the oil passage M-7 are communicated. However, the valve body 60 is placed at the first position in the depressurization process. Therefore, the oil path M-3 and the oil path M-7 are kept connected.

  Then, as the oil discharged by the hydraulic pump 38 is supplied to the second oil chamber 36, the oil in the hydraulic tank 46 is sucked in the hydraulic pump 38, and on the oil path M-3 side, The oil in the hydraulic tank 46 is sucked through the oil passage M-7. Accordingly, since the hydraulic pump 38 can suck the same amount of oil as the oil supplied to the second oil chamber 36, the excess or deficiency of the oil circulation amount in the oil passages M-3 and M-4 is adjusted. be able to.

  In this case, as described above, since the valve body 60 is placed in the first position in the depressurization process, the oil in the hydraulic tank 46 is transferred to the oil path M-3 at the same time as the reverse process is started. Supplied in. Accordingly, since a sufficient amount of oil can be sucked by the hydraulic pump 38, the oil can be rapidly supplied into the second oil chamber 36. As a result, the nozzle touch can be released in a short time and the backward molding can be performed.

  Thus, in the present embodiment, it is not necessary to use a ball screw in order to repeatedly increase or decrease the nozzle touch pressure, so that the durability of the plasticizing moving device 22 is improved. be able to. Further, in order to increase the nozzle touch pressure, the master cylinder 27 and the slave cylinder 28 communicated with each other form the biaxial plasticizing moving device 22, so that the operations of the master cylinder 27 and the slave cylinder 28 are performed. Can be easily synchronized, and the cost of the plasticizing transfer device 22 can be reduced.

  Further, only by operating the hydraulic pump 38 and the switching valve 44, the check valve unit 39 is placed at the first and second positions, and the oil passage M-3 and the oil passage M-7 are selectively communicated. Therefore, the hydraulic circuit 23 can be simplified. Therefore, the plasticizing moving device 22 can be reduced in size.

  When the nozzle touch is completed, the valve body 60 is placed at the first position at the initial position where the hydraulic pump 38 is not operated, so that the depressurization process can be performed in a short time thereafter. Since the valve body 60 is placed in the first position, the backward molding can be performed in a short time thereafter. Thus, since the next process can be performed in a short time, the molding cycle can be shortened.

  Further, since the oil in the oil passages M-3 and M-4 is drained to the hydraulic tank 46 via the hydraulic pump 38, the surface of the oil in the hydraulic tank 46 can be suppressed from undulating. Therefore, it is possible to prevent air from being mixed into the oil. In the hydraulic pump 38, the oil sucked from one of the oil passages M-3 and M-4 is discharged to the other oil passage of the oil passages M-3 and M-4. Therefore, oil can be rapidly supplied to the first and second oil chambers 35 and 36. Therefore, the responsiveness of the plasticizing transfer device 22 can be increased.

  In the present embodiment, the pressure sensor 45 is disposed close to the master cylinder 27. However, the pressure sensor is disposed on the master cylinder 27 or the pressure sensor is disposed on the slave cylinder 28. Alternatively, pressure sensors can be provided in both the master cylinder 27 and the slave cylinder 28.

  In addition, this invention is not limited to the said embodiment, It can change variously based on the meaning of this invention, and does not exclude them from the scope of the present invention.

It is a conceptual diagram which shows the injection molding machine in embodiment of this invention. It is a figure which shows the hydraulic circuit of the plasticizing movement apparatus in embodiment of this invention. It is a figure which shows the principal part of the non-return valve unit in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Mold apparatus 11a Fixed mold 11b Movable mold 13 Injection apparatus 14 Fixed platen 17 Injection nozzle 22 Plasticizing movement apparatus 27 Master cylinder 28 Slave cylinder 31 Cylinder 32 Piston 33 Piston rods 35 and 36 1st, 2nd oil chamber 38 Hydraulic pump 39 Check valve unit 44 Switching valve 46 Hydraulic tank 66, 67 Spring fr Frame M-3, M-4 Oil passage

Claims (6)

(A) a stationary platen attached to the frame;
(B) a mold apparatus comprising first and second molds, wherein the first mold is attached to the fixed platen;
(C) an injection device provided with an injection nozzle and arranged to be movable forward and backward with respect to the frame;
(D) A plastic including a cylinder attached to the injection device, a piston, and a piston rod attached to a fixed portion, wherein a first medium accommodation chamber is formed on the rod side and a second medium accommodation chamber is formed on the head side. A moving cylinder,
(E) a reversible pump;
(F) a first medium flow path connecting the first medium accommodation chamber and the reversible pump;
(G) a second medium flow path connecting the second medium storage chamber and the reversible pump;
(H) a pilot check valve that is disposed between the first and second medium flow paths and communicates the first medium flow path and the medium tank at an initial position where the reversible pump is stopped. Plasticizing moving device.   The plasticizing moving device according to claim 1, wherein the pilot check valve is placed at an initial position by a biasing force by a biasing member.   2. The plasticizing and moving apparatus according to claim 1, wherein the pilot check valve makes the first medium flow path and the medium tank not communicated when supplying the medium to the first medium accommodation chamber.   2. The plasticizing movement device according to claim 1, wherein the pilot check valve causes the first medium flow path and the medium tank to communicate with each other when the medium is supplied to the second medium accommodation chamber.   The plasticizing movement apparatus according to claim 1, wherein a medium pressure holding device for holding the pressure of the medium in the first medium containing chamber is disposed in the first medium flow path. A fixed platen attached to the frame, first and second molds are provided, and the first mold is provided with a mold device attached to the fixed platen and an injection nozzle, and is disposed so as to be movable forward and backward with respect to the frame. And a cylinder attached to the injection device, a piston, and a piston rod attached to a fixed part, and a first medium accommodation chamber is formed on the rod side and a second medium accommodation chamber is formed on the head side. The plasticizing moving cylinder, the reversible pump, the first medium flow path connecting the first medium storage chamber and the reversible pump, and the second medium flow path connecting the second medium storage chamber and the reversible pump. In the plasticizing movement method of the plasticizing movement apparatus having a pilot check valve disposed between the first and second medium flow paths
A plasticizing movement method, wherein the first medium flow path and the medium tank are communicated at an initial position where the reversible pump of the pilot check valve is stopped.

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