JP2006062245A - Plasticizing moving device of electromotive injection molding machine and nozzle touch method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the plasticizing moving device of an electromotive injection molding machine capable of controlling the nozzle touch pressure with high precision and high response by a simple constitution using a hydraulic actuator, and a nozzle touch method. <P>SOLUTION: An injection device 2 is moved by a hydraulic cylinder 20 and a hydraulic pump 24 is driven by a servomotor 28. The driving of the servomotor 28 is controlled by a controller 26 and the oil pressure supplied to the hydraulic cylinder 20 from the hydraulic pump 24 is controlled and the movement of the injection device 2 and nozzle touch pressure are also controlled. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an injection molding machine, and more particularly, a plasticizing moving device that moves an injection device to inject it into a mold while melting resin in an electric injection molding machine, and a nozzle touch performed by such a plasticizing moving device. Regarding the method.

  As an example of a conventional plasticizing moving device, plasticizing is performed by moving an injection device (plasticizing device) by a moving mechanism that obtains thrust by a ball screw shaft driven by an electric motor (motor) with a reduction gear and a ball nut engaged therewith. There is a mobile device. The injection device has a cylinder that melts the resin and a screw that measures the molten resin in the cylinder and discharges it from the nozzle. The nozzle is pressed against the resin supply part of the mold and melted in the mold. Injection injection of resin.

  Pressing the nozzle against the mold is referred to as nozzle touch, and the pressing force of the nozzle against the mold at the time of nozzle touch is referred to as nozzle touch pressure. When the molten resin is injected and injected into the mold, since the molten resin is pressurized to a high pressure, a nozzle touch pressure that does not lose this injection pressure is required. In the plasticizing moving device driven by the above-described electric motor and ball screw, the elastic deformation force of the spring is obtained by moving the injection device toward the mold by driving the electric motor and pressing the injection device against the mold through the spring. To obtain the nozzle touch pressure.

  Here, the nozzle touch pressure requires a high pressure when the mold is closed, for example, in the resin filling step and the pressure holding step. On the other hand, it is not necessary to increase the nozzle touch pressure while the mold is open, such as when taking out the molded product or during the resin weighing process, and the nozzle touch is used to prevent deformation of the mold due to the nozzle touch pressure. It is necessary to reduce the pressure. In other words, while the mold is open, the pressing force by the movable mold does not act on the fixed mold, and if the nozzle touch pressure against the fixed mold is high, problems such as deformation of the fixed mold occur. In order to avoid this, it is necessary to reduce the nozzle touch pressure. Such reduction of the nozzle touch pressure is referred to as “decompression”.

  Also, depending on the molding conditions, when the mold is opened with the nozzle touched and the molded product is taken out, the resin that is not sufficiently solidified in the vicinity of the nozzle is not separated from the molded product, and the yarn is pulled. "Pulling phenomenon" may occur. Therefore, in order to prevent the occurrence of the “thread drawing phenomenon”, a so-called “reverse forming” forming method may be employed. In “reverse molding”, the injection device is retracted in processes other than the filling process and pressure holding process to release the nozzle touch mechanically, and the resin in the nozzle part and the resin in the mold are forcibly separated. , To prevent the “stringing phenomenon”.

As described above, when continuous molding is performed, the nozzle touch pressure is repeatedly changed between the high pressure when the resin is filled and the low pressure or the atmospheric pressure when the mold is opened.
JP 2000-71287 A

  As described above, when the nozzle touch pressure is obtained using the elastic deformation force of the spring, in order to change the nozzle touch pressure, the motor is driven to rotate the ball screw shaft, and the ball screw nut is moved. Change the pressing force. In the case of continuous molding, such a change in nozzle touch pressure is performed for each cycle of molding. Therefore, the ball screw nut repeatedly moves reciprocally at a certain location on the ball screw shaft, and there is a problem that the ball screw shaft is greatly worn locally and the life is shortened.

  Further, since the drive mechanism using the ball screw uses the compression of the spring, the responsiveness is poor and the nozzle touch pressure cannot be changed greatly in a short time. In addition, it is difficult to precisely control the elastic deformation force of the spring, and the nozzle touch pressure cannot be accurately changed in a short time. Furthermore, since the spring is repeatedly compressed, there is a problem that the life of the spring is short.

  The present invention has been made in view of the above-mentioned problems, and has a simple configuration using a hydraulic actuator, and an electric injection molding having a plasticizing moving device that can control the nozzle touch pressure with high accuracy and high responsiveness. It is an object to provide a machine and a nozzle touch method.

  In order to achieve the above-mentioned object, according to the present invention, there is provided a plasticizing moving device for an electric injection molding machine having a plasticizing moving device for moving an injection device provided in an injection molding machine with respect to a mold. A hydraulic actuator provided as a drive source for moving the injection device, and a hydraulic actuator for driving the hydraulic actuator, capable of controlling an output hydraulic pressure and capable of rotating in both directions. A pressure source, connected between the fluid pressure source and the fluid pressure actuator, supplying a working medium discharged from the fluid pressure source to the fluid pressure actuator in a direction toward the mold. A first working medium passage for moving, and connected between the hydraulic pressure source and the hydraulic actuator, and supplying the working medium discharged from the hydraulic pressure source to the hydraulic actuator; The gold A second working medium passage for moving in a direction away from the pressure, a pressure detector for detecting a pressing force of the injection device against the mold, and outputting a detection signal, and the hydraulic pressure based on the detection signal There is provided a plasticizing moving device for an electric injection molding machine, comprising a control device for controlling an operation of a servo motor for driving a source.

  The plasticization moving device of the electric injection molding machine described above further includes a switching valve that opens and closes the first working medium passage, and the control device controls the hydraulic pressure source and the switching valve based on the detection signal. The operation is controlled, and the switching valve preferably has a function as a check valve for the flow of the working medium from the hydraulic pressure source to the hydraulic actuator. Further, the control device controls the operation of the switching valve based on the detection signal so that the pressing force detected by the pressure detector becomes a set value set by the input device, and the set value is It is preferable to include at least two set values of a high pressure set value and a low pressure set value.

  In the above-described plasticizing / moving device of the electrical injection molding machine, the low pressure set value may be used after the completion of the weighing process or during the cooling process. Or it is good also as controlling using the said high voltage | pressure set value during a filling process.

  In the plasticizing moving apparatus for the electrical injection molding machine described above, the control device sets the setting based on at least one of a screw specification value, a detected filling pressure value, and a detected back pressure value. The value may be calculated. The control device may perform at least one of a backward operation of the injection device or a low pressure control of the nozzle touch pressure after a predetermined time has elapsed from the start of the cooling process. Further, the control device may perform at least one of a backward operation of the injection device or a low pressure control of the nozzle touch pressure after a predetermined time has elapsed from the start of the measurement process.

  In the plasticizing / moving apparatus of the electrical injection molding machine described above, the hydraulic pressure source is a hydraulic pump driven by a reverse-rotating servo motor, and the hydraulic pump is connected to the first working medium passage. A first suction / discharge port and a second suction / discharge port to which the second working medium passage is connected, and the rotation direction and rotation speed of the servo motor are controlled by the control device. It is good.

  Further, according to the present invention, there is provided a nozzle touch method for bringing a nozzle into contact with a mold in a plasticizing moving device of an electric injection molding machine, wherein a servo motor is driven and hydraulic pressure is increased by driving the servo motor. The working medium is supplied from the power source to the hydraulic actuator, the pressure of the working medium supplied to the hydraulic actuator is detected by a pressure detector, and the servo is detected based on the pressure detection value detected by the pressure detector. There is provided a nozzle touch method characterized by controlling a motor.

  According to the present invention described above, the nozzle touch pressure can be accurately controlled and held at a desired pressure with a simple configuration in which the operation of the hydraulic pressure actuator is controlled using a hydraulic pressure source capable of adjusting the hydraulic pressure. it can. Further, since a hydraulic actuator is used, there is no need for wear parts such as a ball screw, and a moving mechanism with a long operating life can be realized.

  Next, a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing an overall configuration of a plasticizing moving apparatus provided in an electric injection molding machine according to a first embodiment of the present invention.

  The plasticizing moving device shown in FIG. 1 is provided for moving an injection device 2 provided in an electric injection molding machine. The injection device 2 is supported on a chassis 4 of the molding machine so as to be movable with respect to a stationary platen 8 that supports a stationary mold 6. The moving mold 10 is provided so as to be movable with respect to the fixed mold 6. The resin filling process and the pressure holding process are performed in a state where the moving mold 10 is pressed against the fixed mold 6 and the mold is closed. In a state where the mold 10 is separated from the fixed mold 6 and the mold is opened, a molded product take-out step and a resin weighing step are performed.

  The injection device 2 has a screw 12 for measuring and extruding molten resin, and a nozzle 14 is provided at the tip of the screw 12. Molten resin is discharged from the tip of the nozzle 14. In the filling step of injecting and filling molten resin into the mold, the injection device 2 is moved toward the fixed platen 8 and the nozzle 14 is pressed against the fixed mold 10 or the injection portion of the fixed platen 8 (nozzle touch).

  The plasticizing moving device according to the present embodiment is a moving mechanism for moving the above-described injection device 2, and includes a hydraulic cylinder 20 as a hydraulic actuator and a hydraulic circuit that supplies hydraulic oil as a working medium to the hydraulic cylinder 20. 22, a hydraulic pump 24 that can rotate in both directions as a hydraulic pressure source that generates hydraulic pressure of hydraulic oil (hydraulic pressure of the working medium), and a control device 26 that controls the hydraulic pump 24. In this embodiment, the hydraulic pump 24 is driven by a servo motor 28 as an electric motor that can rotate in the reverse direction and can control the rotation speed.

  The tip of the shaft 20a of the hydraulic cylinder 20 is fixed to the stationary platen 8, and the hydraulic oil pressure applied to the rear side of the hydraulic cylinder 20 by the hydraulic pump 24 is a passage 30 (first hydraulic oil passage). ), The entire injection device 2 moves toward the stationary platen 8 (that is, the mold) (this direction is referred to as the front). On the other hand, by supplying hydraulic oil pressurized by the hydraulic pump 24 to the front side of the hydraulic cylinder 20 via the passage 32 (second hydraulic oil passage), the entire injection device 2 is fixed to the fixed platen 8 (that is, the mold). ) In a direction away from (this direction is referred to as the rear).

  The passage 30 is connected to one suction discharge port 24a (first suction discharge port) of the hydraulic pump 24, and the passage 32 is connected to the other suction discharge port 24b (second suction discharge port) of the hydraulic pump 24. The The hydraulic pump 24 can generate hydraulic pressure by switching the rotation direction of the servo motor 28 to suck hydraulic fluid from one of the suction and discharge ports 24a and 24b and discharge it from the other. The rotational speed and direction of the servo motor 28 are controlled by the control device 26. The hydraulic pump 24 can also suck the hydraulic oil from the tank 34 and discharge the hydraulic oil from one of the discharge ports 24a and 24b.

  The passage 30 is connected to the front oil chamber 20b of the hydraulic cylinder 20, and the passage 32 is connected to the rear oil chamber 20c of the hydraulic cylinder 20. Here, since the shaft 20a passes through the front oil chamber 20b, the cross-sectional area of the front oil chamber 20b is smaller than the cross-sectional area of the rear oil chamber 20c. However, when generating the nozzle touch force, the hydraulic cylinder 20 can be arranged on the injection device 2 by making the side to which the hydraulic oil is supplied the front side, and the molding machine can be made compact.

  A pressure sensor 36 is provided in the middle of the passage 30 for supplying hydraulic oil to the front side of the hydraulic cylinder 20. The pressure sensor 36 detects the hydraulic pressure in the passage 30 and transmits a detection signal to the control device 26. The pressure sensor 36 is provided in the passage 30 near the hydraulic cylinder 20, and the hydraulic pressure detected by the pressure sensor 36 is substantially equal to the hydraulic pressure in the hydraulic cylinder 20. Therefore, the control device 26 can recognize the hydraulic pressure in the hydraulic cylinder 20 based on the detection signal from the pressure sensor 36. Since the nozzle touch pressure that moves the injection device 2 forward and presses the nozzle 14 is generated by the hydraulic pressure on the front side of the hydraulic cylinder 20, the detection signal of the pressure sensor 36 is also a signal representing the nozzle touch pressure.

  When the hydraulic pump 24 is operated and hydraulic oil is discharged from the suction discharge port 24a and supplied to the front side of the hydraulic cylinder 20, the injection device 2 moves forward. The nozzle 14 of the injection device comes into contact with the fixed platen 8 or the fixed mold 6 (nozzle touch). When the hydraulic oil is continuously supplied to the front side of the hydraulic cylinder 20 after the nozzle touch is performed, the hydraulic pressure on the front side in the hydraulic cylinder 20 increases, thereby increasing the nozzle touch pressure. When the nozzle touch pressure becomes a desired high pressure, that is, when the detection signal of the pressure sensor 36 reaches a predetermined level, the control device 26 makes the pressure in the hydraulic cylinder 20 constant at the desired high pressure. The output of the hydraulic pump 24 is controlled by controlling the rotation of the servo motor 28. Thereby, the hydraulic pressure is held on the front side of the hydraulic cylinder 20, and the nozzle touch pressure is also kept at a desired pressure.

  The pressure sensor 36 described above detects the pressure in the hydraulic cylinder 20 as the nozzle touch pressure, but other sensors such as a load cell may be used as long as the nozzle touch pressure is detected.

  When the nozzle touch pressure is reduced after maintaining the nozzle touch pressure at a high level, the hydraulic pump 24 is rotated in the reverse direction by rotating the servo motor 28 in the reverse direction. 24 flows into the suction / discharge port 24a, is discharged from the suction / discharge port 24b to the passage 32, and is supplied to the rear side of the hydraulic cylinder 20. Thereby, the pressure on the front side of the hydraulic cylinder 20 is reduced, and the nozzle touch pressure is reduced. By controlling the rotation speed of the servo motor 28 when the nozzle touch pressure becomes a predetermined low pressure, the low nozzle touch pressure can be maintained.

  When hydraulic oil is supplied to the front side of the hydraulic cylinder 20 and the hydraulic cylinder 20 is operated, the hydraulic oil on the rear side of the hydraulic cylinder 20 flows through the passage 32 and is sucked into the hydraulic pump 24 from the suction discharge port 24b. The oil is discharged from the suction discharge port 24 a to the passage 30 and supplied to the front side of the hydraulic cylinder 20.

  When the injection device 2 is moved backward, the rotation of the servo motor 28 is reversed, the hydraulic oil is discharged from the suction discharge port 24b of the hydraulic pump 24, and the hydraulic oil is discharged to the rear side of the hydraulic cylinder 20 through the passage 32. Supply.

  In this embodiment, check valves 38 and 40 are provided between the passage 30 and the passage 32, and a portion between the two check valves 38 and 40 is connected to the tank 34 by a drain passage 39. Yes. The check valves 38 and 40 and the drain passage 39 form a drain circuit for adjusting the excess or deficiency of the circulating amount of the hydraulic oil due to the difference in the volume between the front side and the rear side of the hydraulic cylinder 20. For example, when the injection device 2 is advanced, hydraulic oil is supplied from the pipe 30 to the front oil chamber 20b, and hydraulic oil is discharged from the rear oil chamber 20c. In this case, since the cross-sectional area of the rear oil chamber 20c is larger than the cross-sectional area of the front oil chamber 20b, the amount of hydraulic oil discharged from the rear oil chamber 20c is the amount of hydraulic oil supplied to the front oil chamber 20b. Become more. On the other hand, if hydraulic oil continues to be supplied from the pump 24 to the pipe 30 in order to advance the injection device 2, the pressure of the hydraulic oil in the pipe 30 increases, and the hydraulic oil in the pipe 30 travels along the pipe 30 a and passes through the pipe 32. The check valve 44 is opened. When the check valve 40 is opened, the hydraulic oil discharged from the rear oil chamber 20 c is returned to the tank 34 through the check valve 40 and the drain passage 39. Therefore, the excess and deficiency of the hydraulic oil in the pipe 30 and the pipe 32 can be adjusted.

  In the hydraulic circuit 22 described above, since the number of valves or valves is small, the system configuration is simplified and compact. In addition, there is little influence of noise caused by valve operation. Furthermore, since the hydraulic circuit 22 is simplified, the hydraulic circuit 22 has few parts that may cause hydraulic oil leakage and is excellent in reliability.

  Further, in the hydraulic circuit 22 described above, the high-pressure hydraulic oil on the front side or the rear side of the hydraulic cylinder 20 is once sucked into the hydraulic pump 24 and then discharged by the hydraulic pump. At this time, only excess hydraulic oil is returned to the tank 34. Therefore, the high pressure hydraulic oil is not returned directly to the tank. When the high-pressure hydraulic oil is returned directly to the tank 34, the oil level in the tank 34 may wave and air may be mixed into the hydraulic oil. In particular, when the tank 34 is made smaller, there is a higher possibility that air will be mixed in. However, in the hydraulic circuit 22 in the present embodiment, the high-pressure hydraulic oil does not return directly to the tank 34, so that air contamination due to this can be prevented.

  Further, in the hydraulic circuit 22 described above, hydraulic oil from the front side of the hydraulic cylinder 20 is returned to the rear side of the hydraulic cylinder 20 via the hydraulic pump 24. Here, when the hydraulic oil from the front side of the hydraulic cylinder 20 is returned to the tank 34 and then sucked by the hydraulic pump 24 and supplied to the rear side of the hydraulic cylinder 20, the hydraulic oil for depressurization (the front side of the hydraulic cylinder 20 is In this case, the hydraulic oil must be sucked and discharged by the hydraulic pump, and the return of the hydraulic oil to the tank must be awaited to start the backward operation of the injection device. However, in the hydraulic circuit 22 according to the above-described embodiment, since the hydraulic oil is discharged immediately after returning to the hydraulic pump 24, the backward operation can be started immediately, and the molding cycle time can be shortened.

  As described above, in this embodiment, hydraulic pressure is generated by the pump 24 driven by the servo motor 28, and the rotational speed and direction of the servo motor 28 are controlled by the control device 26 based on the detection signal from the pressure sensor 36. With this simple configuration, the nozzle touch pressure can be controlled and maintained at a desired pressure.

  Further, since the hydraulic oil on the front side and the rear side of the hydraulic cylinder 20 is only circulated through the hydraulic pump, the suction pressure of the hydraulic pump 24 becomes the pressure in the hydraulic cylinder 20 higher than the atmospheric pressure, and the compression ratio is reduced. The hydraulic pump 24 can be operated efficiently. Further, it is not necessary to pressurize again after returning the pressure of the hydraulic oil to atmospheric pressure (that is, after returning to the tank 34), and the heat generation of the hydraulic oil can be suppressed, so that deterioration of the hydraulic oil can be suppressed.

  In addition, since the hydraulic circuit 22 is not provided with a restriction that restricts the flow of hydraulic oil, the pressure control response of the hydraulic cylinder 20 is good. For example, the retraction operation of the injection device 2 at the time of reverse molding can be performed quickly. Can be done. Furthermore, the heat generation of the hydraulic oil can be suppressed.

  Further, since the hydraulic oil flow is switched by switching the rotation direction of the hydraulic pump 24 based on the detection signal of the pressure sensor 36, the circuit configuration is simplified compared to a hydraulic control circuit that controls pressure using a pressure switch or the like. .

  Furthermore, since the hydraulic actuator (hydraulic cylinder 20) is used, there is no need for parts that wear like ball screws, and a moving mechanism with a long operating life can be realized.

  Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a view showing the entire configuration of a plasticizing moving device provided in the electric injection molding machine according to the second embodiment of the present invention. 2, parts that are the same as the parts shown in FIG. 1 are given the same reference numerals, and descriptions thereof will be omitted.

  The plasticizing / moving device according to the second embodiment of the present invention has the same basic configuration as that of the first embodiment, except that safety valves 42 and 44 are provided in the hydraulic circuit 22. The safety valves 42 and 44 are relief valves that release the pressure when the hydraulic pressure reaches the set pressure and prevent the hydraulic pressure from exceeding the set pressure. The set pressure (relief pressure) is set to a high pressure that is not the normal operation of the hydraulic circuit, and the safety valves 42 and 44 function to protect the hydraulic circuit when the hydraulic circuit becomes abnormally high due to some malfunction. Fulfill.

  Specifically, the safety valve 42 is connected in the middle of the passage 30 to release the pressure when the hydraulic pressure in the passage 30 becomes an abnormally high pressure, thereby preventing the passage 30 from being damaged. Similarly, the safety valve 44 is connected in the middle of the passage 32 to release the pressure when the hydraulic pressure in the passage 32 becomes abnormally high, thereby preventing the passage 32 from being damaged.

  As described above, according to this embodiment, in addition to the effects obtained in the first embodiment, when the safety valves 42 and 44 are provided, for example, when the hydraulic pump 24 fails and an abnormal high pressure occurs. Even so, the pressure can be released so as not to exceed the set pressure in the hydraulic circuit 22, and damage to the hydraulic circuit 22 can be prevented.

  Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a diagram showing an overall configuration of a plasticizing moving apparatus provided in an electric injection molding machine according to a third embodiment of the present invention. 3, parts that are the same as the parts shown in FIGS. 1 and 2 are given the same reference numerals, and descriptions thereof will be omitted.

  The plasticizing and moving apparatus according to the third embodiment of the present invention has the same basic configuration as that of the first embodiment described above, except that safety valves 42 and 44 and a switching valve 46 are provided in the hydraulic circuit 22. The safety valves 42 and 44 perform the same function as in the second embodiment described above. The switching valve 46 may be a normal block switching valve, but is preferably a check valve switching valve as shown in FIG.

  In this embodiment, the switching valve 46 is provided in the passage 30 and the switching valve 46 is closed in the filling process and the pressure holding process, so that the pressure on the front side of the hydraulic cylinder 20 is maintained and the nozzle touch pressure is kept high. To do. Therefore, while the switching valve 46 is closed, the hydraulic pump 24 can be stopped without being driven or can be idling. Thereby, the drive time of the hydraulic pump 24 can be reduced, and the power consumption of the servo motor 28 can be reduced. Also, when the nozzle touch pressure is held at a low pressure, the switching valve 46 can be closed to stop the drive of the hydraulic pump, or the idling drive can be performed.

  As described above, according to the present embodiment, in addition to the effects obtained in the second embodiment, the switching valve 46 is provided in the passage 30 to shorten the time during which the hydraulic pump 24 is driven. The power consumption of the servo motor 28 can be reduced.

  Next, the molding process performed by the injection molding machine using the plasticizing / moving apparatus according to the first and second embodiments will be described.

  FIG. 4 is a flowchart showing an example of a molding process performed in an injection molding machine provided with the plasticizing / moving device according to the above-described embodiment. The molding process shown in FIG. 3 is referred to as a “nozzle touch force depressing molding process”, and is a molding process for reducing the nozzle touch pressure when the mold is opened. Reducing the nozzle touch pressure when opening the mold is called “depressurization”.

  First, in step S1, the servo motor 28 is driven to operate the hydraulic pump 24, the injection device (injection unit) 2 is advanced to perform nozzle touch, and the nozzle touch pressure is increased. When the nozzle touch pressure becomes a desired high pressure based on the detection signal of the pressure sensor 36, the servo motor 28 is controlled to a constant rotational speed, and the output of the hydraulic pump 24 is maintained as it is. Thereby, the hydraulic pressure on the front side of the hydraulic cylinder 20 is maintained at a desired high pressure, and the nozzle touch pressure is also maintained at a high pressure. Here, the high pressure is a contact pressure at which the molten resin does not leak from between the nozzle 14 and the stationary mold 6 in the filling step and the pressure holding step.

  While the nozzle touch pressure is maintained at a desired high pressure, a filling process is performed in step S2, and the molten resin is injected from the injection device 2 into the mold through the nozzle 14 and filled. When the filling process is completed, a pressure holding process is performed in step S3, and the resin filled in the mold is held with pressure applied. This fills the entire mold with the molten resin.

  When the pressure holding step in step S3 is completed, the process proceeds to steps S4, S5, and S7. In step S4, a cooling process is performed, and the molten resin in the mold is cooled and solidified by cooling the mold. A delay count is started simultaneously with the start of the cooling process. When the delay count ends, that is, when the delay time is reached, in step S5, the hydraulic pump is reversely driven to drive the injection device 2 backward ("backward during cooling"). In step S6, the time until the timer starts counting and the subsequent “depressurization” is started is measured. Further, while the cooling process is being performed in the mold, in the injection device 2, the screw 12 is moved backward while rotating in step S7, and the molten resin is metered.

  In the case of performing “retraction during cooling”, the injection device 2 is retracted in the cooling process and the nozzle touch is released, so that the depressurization in steps S8 to S11 described later is not performed. Further, instead of “retreat during cooling”, the injection device 2 may be retracted (“retreat after measurement”) after the measurement process is completed. In addition, when performing “depressurization” in which the nozzle touch pressure is reduced in steps S8 to S11 described later, the above-described delay counter in step S4 and “retraction during cooling” or “retraction after measurement” in step S5 are performed. Absent. In the present embodiment, any one of a mode for performing “retraction during cooling”, a mode for performing “retraction after measurement”, and a mode for performing only “decompression” can be selected. In addition, the timing of performing “backward during cooling”, “backward after measurement”, or “depressurization” can be set by the count value of the timer.

  When the predetermined count is finished in step S6, the rotational speed of the servo motor 28 is reduced in step S8 to reduce the output of the hydraulic pump 24. As a result, the hydraulic pressure on the front side of the hydraulic cylinder 20 is reduced, and “decompression” is performed to reduce the nozzle touch pressure. Here, the low pressure is a pressure at which the molten resin does not leak from between the nozzle 14 and the fixed mold 6 when back pressure is applied in the measuring step. Subsequently, in step S9, the movable mold 10 is moved to open the mold while maintaining the output of the hydraulic pump 24 (that is, the output of the servo motor 28) so as to maintain the nozzle touch pressure at a low pressure. The molded product is taken out from this, and this molding process is completed.

  In the nozzle touch method used in the above molding process, by providing a plurality of pressure setting values, the nozzle touch pressure is kept high while driving the hydraulic pump, and then the output of the hydraulic pump is reduced. The nozzle touch pressure can be reduced and held. Therefore, the nozzle touch pressure can be controlled only by operating the hydraulic pump (servo motor), and a mechanical movement operation or the like is unnecessary, and the nozzle touch pressure can be controlled with a simple configuration.

  In addition, the high pressure set value and the low pressure set value may be calculated based on a predetermined screw specification value, based on a filling pressure detection value or a back pressure detection value formed during molding. Alternatively, it may be calculated.

  FIG. 5 is a flowchart showing an example of a molding process performed in an injection molding machine provided with the plasticizing / moving device according to the above-described embodiment. The molding process shown in FIG. 5 is referred to as a “nozzle touch force touchback molding process”, and is a molding process in which the injection device 2 is moved backward when the mold is opened and the nozzle 14 is temporarily separated from the fixed mold 6.

  Steps S1 to S7 are the same as the “nozzle touch force depressurization molding process” shown in FIG. When the timer count ends in step S6, the rotation of the servo motor 28 is switched in step S10, and the hydraulic pump 24 is reversed. As a result, the hydraulic pump 24 sucks hydraulic oil from the suction discharge port 24a and discharges it from the suction discharge port 24b. Thereby, in step S11, the hydraulic oil is transferred from the front side to the rear side of the hydraulic cylinder 20, and the injection device 2 moves backward (corresponding to “backward after measurement”). When the injection device 2 is retracted and the nozzle 14 is separated from the fixed mold 6 (touch back), the movable mold 10 is moved and the mold is opened in step S12, and the molded product is taken out from the mold, and this molding is performed. The process ends.

  In the nozzle touch method used in the molding process described above, the nozzle touch pressure is maintained at a high level while driving the hydraulic pump, and then the injection device is moved backward to release the nozzle touch by reversing the hydraulic pump. Therefore, the nozzle touch pressure can be controlled only by operating the hydraulic pump (servo motor), and no mechanical movement operation is required, and the nozzle touch can be controlled with a simple configuration.

  Next, a molding process performed by an injection molding machine using the plasticizing / moving device according to the third embodiment will be described.

  FIG. 6 is a flowchart showing an example of a molding process performed in an injection molding machine provided with the plasticizing / moving device according to the third embodiment. The molding process shown in FIG. 6 is referred to as a “nozzle touch force depressing molding process”, and is a molding process for reducing the nozzle touch pressure when the mold is opened. Reducing the nozzle touch pressure when opening the mold is called “depressurization”.

  The forming process shown in FIG. 6 is basically the same as the forming process shown in FIG. 4 except that the switching valve 46 is closed to maintain a high or low pressure nozzle touch pressure. That is, in the molding process shown in FIG. 6, when the nozzle touch pressure becomes high in step S1, the switching valve 46 is closed and the drive of the hydraulic pump 24 is stopped. When the timer count in step S6 ends, the switching valve 46 is opened in step S21, and the pressure on the front side of the hydraulic cylinder 20 is reduced to perform "decompression". When the pressure on the front side of the hydraulic cylinder 20 becomes a predetermined low pressure, the switching valve is closed again in step S22 to maintain the low pressure. Thereafter, in step S23, the mold is opened while the pressure is released, and the molded product is taken out.

  FIG. 7 is a flowchart showing an example of a molding process performed in the injection molding machine provided with the plasticizing / moving device according to the third embodiment. The molding process shown in FIG. 4 is referred to as a “nozzle touch force touch back molding process”, and is a molding process in which the injection device 2 is moved backward when the mold is opened to temporarily separate the nozzle 14 from the fixed mold 6.

  Steps S1 to S7 and S21 are the same as the “nozzle touch force press-forming process” shown in FIG. When the switching valve 46 is opened in step S21, the hydraulic pump 24 (servo motor 28) is driven in step S24 (driven in the opposite direction to step S1), and the hydraulic oil on the front side of the hydraulic cylinder 20 is supplied to the hydraulic cylinder by the hydraulic pump 24. 20 is transferred to the rear side. Thereby, in step S25, the injection device 2 moves backward, and the nozzle 14 moves away from the fixed mold 6. Thereafter, in step S26, the movable mold 10 is moved to open the mold, the molded product is taken out from the mold, and the current molding process is completed.

  In the present embodiment, an example using a hydraulic cylinder has been described, but an air cylinder driven by compressed air or the like may be used instead of the hydraulic cylinder.

It is a figure which shows the whole structure of the plasticizing movement apparatus provided in the electric injection molding machine by 1st Example of this invention. It is a figure which shows the whole structure of the plasticizing movement apparatus provided in the electric injection molding machine by 2nd Example of this invention. It is a figure which shows the whole structure of the plasticizing movement apparatus provided in the electric injection molding machine by 3rd Example of this invention. It is a flowchart of the "nozzle touch force depressurization molding process" performed in the electric injection molding machine incorporating the plasticizing movement apparatus by the 1st and 2nd Example of this invention. It is a flowchart of the "nozzle touch force touch back molding process" performed in the electric injection molding machine incorporating the plasticizing movement apparatus by the 1st and 2nd Example of this invention. It is a flowchart of the "nozzle touch force depressurization molding process" performed in the electric injection molding machine incorporating the plasticizing movement apparatus by 3rd Example of this invention. It is a flowchart of the "nozzle touch force touch back molding process" performed in the electric injection molding machine incorporating the plasticizing movement apparatus by 3rd Example of this invention.

Explanation of symbols

2 Injection Device 4 Chassis 6 Fixed Mold 8 Fixed Platen 10 Movable Mold 12 Screw 14 Nozzle 20 Hydraulic Cylinder 22 Hydraulic Circuit 24 Hydraulic Pump 26 Control Circuit 28 Servo Motor 30, 32 Passage 34 Tank 36 Pressure Sensor 38, 40 Check Valve 39 Drain passage 42, 44 Safety valve 46 Switching valve

Claims (10)

A plasticizing moving device for an electric injection molding machine having a plasticizing moving device for moving an injection device provided in an injection molding machine with respect to a mold,
A hydraulic actuator provided as a drive source for moving the injection device;
A hydraulic pressure source for driving the hydraulic actuator, capable of controlling the output hydraulic pressure, and capable of rotating in both directions;
Connected between the fluid pressure source and the fluid pressure actuator, and supplies the working medium discharged from the fluid pressure source to the fluid pressure actuator to move the injection device in the direction toward the mold. A first working medium passage;
Connected between the fluid pressure source and the fluid pressure actuator to supply a working medium discharged from the fluid pressure source to the fluid pressure actuator to move the injection device away from the mold. A second working medium passage of
A pressure detector that detects a pressing force of the injection device against the mold and outputs a detection signal;
And a control device that controls the operation of a servo motor that drives the hydraulic pressure source based on the detection signal. It is a plasticizing movement device of the electric injection molding machine according to claim 1,
A switching valve for opening and closing the first working medium passage;
The control device controls operations of the hydraulic pressure source and the switching valve based on the detection signal,
The switch valve has a function as a check valve for a flow of a working medium from the hydraulic pressure source to the hydraulic actuator, and is a plasticizing movement device for an electric injection molding machine. A plasticizing transfer device for an electric injection molding machine according to claim 2,
The control device controls the operation of the switching valve based on the detection signal so that the pressing force detected by the pressure detector becomes a set value set by the input device, and the set value is at least An apparatus for plasticizing and moving an electrical injection molding machine, comprising two set values, a high pressure set value and a low pressure set value. A plasticizing transfer device for an electrical injection molding machine according to claim 3,
An apparatus for plasticizing and moving an electric injection molding machine, wherein the low-pressure set value is controlled after completion of a weighing process or during a cooling process. A plasticizing transfer device for an electrical injection molding machine according to claim 3,
A plasticizing movement device for an electrical injection molding machine, wherein the high pressure set value is used to control during the filling step. A plasticizing transfer device for an electrical injection molding machine according to claim 2,
The control device calculates the set value based on at least one of a screw specification value, a detected filling pressure value, and a detected back pressure value. Plasticizing transfer device. A plasticizing transfer device for an electrical injection molding machine according to any one of claims 1 to 6,
The control device performs at least one of a reverse operation of the injection device or a low pressure control of the nozzle touch pressure after a predetermined time has elapsed from the start of the cooling process, and the plasticizing movement of the electrical equipment injection molding machine apparatus. A plasticizing transfer device for an electrical injection molding machine according to any one of claims 1 to 6,
The control device performs at least one of the backward operation of the injection device or the low pressure control of the nozzle touch pressure after a predetermined time has elapsed from the start of the metering process, and the plasticizing movement of the electrical injection molding machine, apparatus. A plasticizing transfer device for an electrical injection molding machine according to any one of claims 1 to 8,
The hydraulic pressure source is a hydraulic pump driven by a servo motor capable of reverse rotation,
The hydraulic pump has a first suction / discharge port to which the first working medium passage is connected, and a second suction / discharge port to which the second working medium passage is connected,
The plasticizing movement device of the electrical injection molding machine, wherein the rotation direction and rotation speed of the servo motor are controlled by the control device. A nozzle touch method for bringing a nozzle into contact with a mold in a plasticizing moving device of an electric injection molding machine,
Drive the servo motor,
By driving the servo motor, a working medium is supplied from a hydraulic pressure source to a hydraulic actuator,
The pressure of the working medium supplied to the hydraulic actuator is detected by a pressure detector;
A nozzle touch method comprising: controlling the servo motor based on a pressure detection value detected by the pressure detector.

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