JP5210698B2 - Pre-plastic injection molding machine - Google Patents

Description

  The present invention relates to a pre-plastic injection molding machine in which a plasticizing part of a molding material and an injection part of a plasticized molding material are separately provided. In particular, the plasticizing chamber, the injection chamber, and these chambers communicate with each other. The present invention relates to a means for preventing the molding material from staying in the molding material passage.

  As shown in FIG. 7, the pre-plastic injection molding machine rotates a screw 102 in a heating cylinder 101 to plasticize and knead a molding material, and an injection plunger 105 advances and retreats in the injection cylinder 104. And an injection portion 107 for injecting the molding material 106 plasticized and kneaded in the plasticizing portion 103 into the mold, and the molding material 106 plasticized and kneaded in the plasticizing portion 103 is heated by a heating cylinder. 101 and the injection cylinder 104 are supplied into the injection cylinder 104 through the molding material passage 108 communicating with each other, the molding material supplied in the injection cylinder 104 is measured, and the molding material in the injection cylinder 104 reaches a predetermined amount. After that, the injection plunger 105 is moved forward to inject the molding material 106 into the mold 109. In contrast, the in-line type injection molding machine performs plasticizing and kneading of the molding material and injection of the molding material into the mold 109 with one screw 102 as shown in FIG. The screw 102 is rotated in 101 to plasticize, knead and measure the molding material. When a predetermined amount of the molding material is accumulated in front of the screw 102, the screw 102 is rapidly advanced to move inside the mold 109. The molding material is injected into the mold.

  In FIG. 7, reference numeral 110 denotes a plasticizing motor for rotating the screw 102, reference numeral 111 denotes an injection motor for moving the injection plunger 105 forward and backward, and reference numeral 112 denotes a plasticizing chamber provided in the heating cylinder 101. Reference numeral 113 denotes an injection chamber provided at the tip of the injection cylinder 104, and reference numeral 114 denotes an injection hole formed in the injection cylinder 104. In FIG. 8, reference numeral 110 denotes a plasticizing motor for rotating the screw 102, reference numeral 121 denotes an injection motor for moving the screw 102 back and forth, and reference numeral 122 denotes an injection chamber provided at the tip of the heating cylinder 101. Reference numeral 123 denotes an injection hole formed in the heating cylinder 101.

  In general, the pre-plastic injection molding machine has a plasticizing part 103 that is separate from the injection part 107, compared to the in-line type injection molding machine, so the plasticizing ability of the molding material is large and high cycle molding is possible. It has the advantage of being. However, the pre-plastic injection molding machine has the following drawbacks compared to the in-line injection molding machine. That is, first, as is apparent from a comparison between FIG. 7 and FIG. 8, the pre-plastic injection molding machine has a molding material 106 plasticized and kneaded by a plasticizing portion 103 at a front portion of an injection plunger 105. Since it is necessary to communicate with the molding material passage 108 for supplying the gas into the injection cylinder 104, the amount of the molding material staying in the injection chamber 113 is larger than that of the in-line type injection molding machine. Tends to cause molding defects due to deterioration of the molding material such as resin burning. In addition, since the heating cylinder 101 and the injection cylinder 104 are communicated with each other via the molding material passage 108, the molding material in the injection chamber 113 easily flows back to the heating cylinder 101 side by the pressure at the time of measurement and injection, Since it is difficult to fill a predetermined amount of a molding material in the mold 109, a molding defect due to a defective filling amount is likely to occur.

  Conventionally, as a means for solving the first problem, the injection plunger 105 is provided with a check ring for preventing a backflow, and an opening on the injection cylinder 104 side of the molding material passage 108 is provided on the base side of the injection plunger 105, At the time of molding, the molding material plasticized and kneaded by the plasticizing portion 103 is passed through the molding material passage 108, the molding material passage formed between the injection cylinder 104 and the injection plunger 105, and the check ring to the front of the injection cylinder. A technique for preventing the molding material from entering the gap between the injection cylinder 104 and the injection plunger 105 by a check ring during supply and injection has been proposed (see Patent Document 1).

Conventionally, as a means for solving the second problem, a technique of installing a check ball valve in the molding material passage 108, and one end of the injection cylinder 104 are opened to a required wall surface of the injection chamber 113, There has been proposed a technique of providing an injection sub-path for preventing a stay whose other end communicates with the injection hole 114 (see Patent Document 2).
JP 59-81144 A JP-A-6-23796

  However, the technique disclosed in Patent Document 1 is provided with a check ring for preventing backflow in the injection plunger 105 and a molding material passage 108 is formed between the injection cylinder 104 and the injection plunger 105, so that the configuration is complicated. Not only does the cost of the injection molding machine increase, but the molding material tends to stay in the gap formed between the injection cylinder 104 and the check ring and the gap formed between the injection plunger 105 and the check ring. Malfunctioning of the molding machine due to deterioration of the molding material is likely to occur. In addition, among the techniques disclosed in Patent Document 2, in the case where a check ball valve is installed in the molding material passage 108, the molding material is likely to stay in a gap formed around the check ball valve. As a result, a malfunction of the molding machine due to deterioration of the molding material is likely to occur. Further, among the techniques disclosed in Patent Document 2, the injection cylinder 104 provided with the injection sub-path for preventing the retention is complicated in the configuration of the injection cylinder 104, which increases the cost of the injection molding machine.

  The present invention has been made in order to solve the problems of the prior art, and the object thereof is to achieve a high-quality molded product that has a simple configuration and can be implemented at low cost and can suppress the retention of molding material. An object of the present invention is to provide a pre-plastic injection molding machine that can be molded efficiently.

In order to achieve this object, the present invention firstly, a plasticizing section for plasticizing and kneading a molding material by rotating a screw in a heating cylinder, and an advancing and retreating an injection plunger in the injection cylinder. A molding material passage for communicating an injection part for injecting a molding material plasticized and kneaded in the plasticizing part into a mold, a plasticizing chamber provided in the plasticizing part, and an injection chamber provided in the injection part And a control unit for controlling the driving of the plasticizing unit and the injection unit, wherein the control unit is configured to perform the injection after the injection of the molding material into the mold is completed. The plunger is retracted to a position where the molding material passage is opened, and the molding material is supplied from the plasticizing chamber into the injection chamber. After the molding material is filled in the injection chamber, the injection plunger is Advance to a predetermined advance position Te, injection and performs the metering of the molding material to be injection-molded material into the mold within in the mold, by changing the retracted position of the injection plunger, wherein during retraction of the injection plunger The opening of the molding material passage is adjusted to control the kneading state of the molding material in the plasticizing chamber .

According to this configuration, by setting the retracted position of the injection plunger in the vicinity of the molding material passage, the molding material passage can be closed by the injection plunger at an early stage of the injection process, so that the resin acting on the molding material passage at the time of injection The pressure can be reduced. Therefore, it is not necessary to set a check ball valve in the molding material passage or to form an injection sub-passage to the injection cylinder, which is generated by simplifying and reducing the cost of the molding machine and providing the check ball valve. The retention of the molding material can be prevented. In addition, since the molding material passage can be arranged behind the front end of the injection plunger when the injection is completed, the amount of the molding material remaining in the injection plunger can be reduced. Furthermore, after the injection chamber is filled with the molding material, the injection plunger is advanced to a predetermined advance position to measure the molding material injected into the mold and inject the molding material into the mold. By regulating the retreat position and the advance position of the injection plunger, the molding material injected into the mold can be accurately measured. The kneading state of the molding material in the plasticizing chamber changes depending on the resin pressure in the plasticizing chamber acting when the screw rotates. The higher the resin pressure, the better the kneading state of the molding material. On the other hand, the resin pressure in the plasticizing chamber varies depending on the opening of the molding material passage, and the resin pressure increases as the opening of the molding material passage decreases. Therefore, the kneading state of the molding material in the plasticizing chamber can be appropriately controlled by adjusting the opening of the molding material passage when the injection plunger is retracted, and a good product can be molded with high efficiency.

The present invention is in the second, in the first pre-plasticization type injection molding machine, the control unit, by changing at least one of the forward position and the backward position of the injection plunger, said to the die in The filling amount of the molding material is controlled.

  In order to mold a high-quality molded product, it is indispensable to fill the mold with sufficient molding material. To fill the mold with sufficient molding material, the mold is injected into the mold. The amount of molding material to be measured must be measured. The amount of molding material injected into the mold is the product of the cross-sectional area of the injection cylinder and the amount of movement from the retracted position of the injection plunger to the advanced position, so the controller controls the retracted and advanced positions of the injection plunger. By doing so, the filling amount of the molding material in the mold can be strictly controlled, and a high-quality molded product can be stably molded.

The present invention is the third, the in the first pre-plasticization type injection molding machine, wherein, in the process of advancing the injection plunger to said advanced position from the retracted position, closing the molding material channel by the injection plunger And it was set as the structure which prevents the backflow of the said molding material to the said plasticization chamber.

  In this way, in the process of moving the injection plunger from the retracted position to the advanced position, if the molding material passage is closed by the injection plunger to prevent the molding material from flowing back to the plasticizing chamber, the resin pressure at the time of injection is almost the molding material. Since it does not act on the passage, there is no need to install a check mechanism such as a check ball valve in the molding material passage, the configuration of the molding machine can be simplified, the molding machine can be implemented at low cost, and the molding material can be retained. It is possible to prevent the malfunction of the molding machine due to the deterioration of the molding material.

The present invention is in the fourth, in the first to third pre-plasticization type injection molding machine, as a drive source for the injection plunger, and the configuration of using a servo motor.

  In a pre-plastic injection molding machine, a hydraulic cylinder is often used as a drive source for an injection plunger. However, depending on the hydraulic cylinder, it is difficult to precisely control the retreat position and the advance position of the injection plunger. On the other hand, if a servo motor is used, the retraction position and the advance position of the injection plunger can be controlled with high accuracy within the range of the resolution of the servo motor, so that the molding material injected into the mold is strictly metered. Therefore, a high-quality molded product can be formed.

  In the pre-plastic injection molding machine of the present invention, after the injection of the plasticized material into the mold is completed by the control unit, the injection plunger is retracted to the position where the molding material passage is opened, and the injection is made from the plasticizing chamber. After the molding material is supplied into the chamber, and the molding material is filled in the injection chamber, the injection plunger is advanced to a predetermined advance position to measure the molding material injected into the mold and into the mold. Since injection of the molding material is performed, setting of a check mechanism for the molding material passage and formation of an injection sub-path for the injection cylinder can be made unnecessary, and the molding machine can be simplified and the cost can be reduced. Further, since a check mechanism is not required, retention of the molding material generated by providing the check mechanism can be prevented, and malfunction of the molding machine due to deterioration of the molding material can be prevented. Furthermore, since the molding material passage can be arranged behind the front end of the injection plunger when the injection is completed, the amount of the molding material staying in the injection plunger can be reduced, and molding defects caused by deterioration of the molding material can be prevented. be able to. In addition, since the molding material injected into the mold can be precisely measured by controlling the retracted position and the advanced position of the injection plunger, a high-quality molded product can be molded with high efficiency.

  Hereinafter, a pre-plastic injection molding machine according to an embodiment will be described with reference to FIGS. FIG. 1 is a cross-sectional view of a pre-plastic injection molding machine according to the embodiment when the injection plunger is retracted, and FIG. 2 is a cross-sectional view showing a filling state of a molding material into the injection chamber of the pre-plastic injection molding machine according to the embodiment. FIG. 4 is a cross-sectional view of the pre-pla injection molding machine according to the embodiment when the injection plunger moves forward, FIG. FIG. 6 is a flow diagram showing the operation of the pre-plastic injection molding machine according to the embodiment, and FIG. 6 is a configuration diagram of a control device provided in the pre-plastic injection molding machine according to the embodiment.

  As shown in FIGS. 1 to 3, the pre-plastic injection molding machine according to the embodiment is plasticized by a plasticizing part 1 of a molding material, an injection part 2 of a plasticized molding material, and a plasticizing part 1. And a molding material passage 4 for supplying the kneaded molding material to the injection unit 2, a control device (control unit) 5 for controlling the driving of the plasticizing unit 1 and the injection unit 2, and a retraction of the injection plunger 22 to the control device 5. An input device 6 for inputting required data including a position and a forward position, a display device 7 for displaying data inputted from the input device 6 to the control device 5, data calculated by the control device 5, and the like, and a control device And a motor driver circuit 8 that generates drive signals for the motors provided in the plasticizing unit 1 and the injection unit 2 based on a control signal output from the control unit 5. Therefore, the pre-plastic injection molding machine according to the embodiment can adjust the filling amount of the molding material into the mold by inputting the retreat position and the advance position of the injection plunger 22 to the input device 6.

  The plasticizing unit 1 includes a heating cylinder 11, a screw 12 rotatably disposed in the heating cylinder 11, a plasticizing servo motor 13 that rotationally drives the screw 12, and a rotational position of the plasticizing servo motor 13. The space formed between the inner wall of the heating cylinder 11 and the outer wall of the screw 12 is provided in a plasticizing chamber 15 for storing a plasticized molding material. It has become.

  The injection unit 2 is a rotation detector such as an injection cylinder 21, an injection plunger 22 disposed in the injection cylinder 21 so as to be able to advance and retreat, an injection servo motor 23, and a rotary encoder that detects the rotation position of the injection servo motor 23. And a ball screw mechanism 25 that converts the rotational movement of the injection servo motor 23 into a linear movement of the injection plunger 22, and a linear motion block 26 connected to the ball screw mechanism 25. The space in front of the position is an injection chamber 27 for storing the plasticized molding material. The ball screw mechanism 25 includes a nut body 25 a having one end connected to the injection plunger 22, and a screw shaft 25 b screwed to the nut body 25 a and having one end connected to the output shaft of the injection servomotor 23. The linear motion block 26 is connected to the nut body 25a. When the servo motor 23 for injection is rotated in the reverse direction, the nut body 25a moves to the left in the figure to advance the injection plunger 22. On the other hand, when the injection servomotor 23 is rotated forward, the nut body 25a moves in the right direction in the figure, and the injection plunger 22 is moved backward. Thus, since the pre-plastic injection molding machine according to the embodiment uses the servo motor as a power source for moving the injection plunger 22 forward and backward, the retraction position and the advance position of the injection plunger 22 are set within the resolution range. It can be controlled with high accuracy. Therefore, the molding material injected into the mold can be accurately measured, and a high-quality molded product can be molded.

  A nozzle 29 communicating with the injection chamber 27 through the injection hole 28 is formed in front of the injection chamber 27, and the tip of the nozzle 29 is abutted against the spool portion 32 of the mold cavity 31. In the figure, reference numeral 33 denotes a fixed mold, reference numeral 34 denotes a fixed platen, reference numeral 35 denotes a movable mold, and reference numeral 36 denotes a movable platen. The fixed mold 33 and the movable mold 35 are not shown. The mold opening / closing mechanism opens and closes at a required timing.

  As shown in FIGS. 1, 2, and 4, the pre-plastic injection molding machine of the present example is such that the opening 4 a on the injection portion 2 side of the molding material passage 4 is retracted to a predetermined retracted position. It is opened at a position corresponding to the part or slightly ahead of it. With this configuration, as is apparent from a comparison between FIG. 2 and FIG. 7, the retention amount of the molding material staying in the front portion of the injection plungers 22 and 105 is reduced as compared with the conventional pre-plastic injection molding machine. Therefore, it is possible to prevent deterioration of the molding material due to heat and to prevent occurrence of molding defects. Further, with such a configuration, the molding material flows from the molding material passage 4 into the injection chamber 27 along the distal end portion of the injection plunger 22, so that the molding material does not easily stay at the distal end portion of the injection plunger 22, and Occurrence of molding defects due to deterioration can be prevented.

  As described above, the opening 4a on the injection portion 2 side of the molding material passage 4 can be opened at a position corresponding to the distal end portion of the injection plunger 22 that has been retracted to a predetermined retracted position, or slightly forward of that. The relationship between the opening position of the opening 4 a and the tip position of the injection plunger 22 is determined in consideration of the kneading state of the molding material in the plasticizing chamber 15. That is, the kneading state of the molding material in the plasticizing chamber 15 becomes better as the resin pressure in the plasticizing chamber 15 acting when the screw 12 rotates is higher. Therefore, when the molded product that requires a molding material having a high degree of kneading is formed, the degree of opening of the molding material passage 4 is reduced to increase the degree of kneading of the molding material. When molding a molded product that does not require a high molding material, the degree of kneading of the molding material is suppressed by increasing the opening of the molding material passage 4. As a result, for molded products that require molding materials with a high degree of kneading, good products can be molded, and for molded products that do not require molding materials with a high degree of kneading, wasteful kneading can be suppressed, and molding efficiency can be reduced. Can be increased.

  As shown in FIG. 5, the control device 5 outputs the output signal a of the rotation detector 14 of the plasticizing servo motor 13, the output signal b of the rotation detector 24 of the injection servo motor 23, and the output signal c of the input device 6. And an output unit 52 for outputting a control signal e for the plasticizing servomotor 13 and a control signal f for the injection servomotor 23 to the motor driver circuit 8. A storage unit 53 that stores an operation program of the pre-plastic injection molding machine according to the embodiment, various parameters necessary for the operation, an output signal c of the input device 6, and the pre-plastic injection molding machine according to the embodiment. The timer 54 for measuring the operation timing of the rotation detector 14, the output signal a of the rotation detector 14 taken into the input unit 51, the output signal b of the rotation detector 24, and the storage unit 53. The display signal d of the display device 7, the control signal e of the plasticizing servo motor 13, and the control signal g based on the program g, various parameters h, the output signal c of the input device 6, and the time signal i input from the timer 54 And an arithmetic control unit 55 that calculates a control signal f of the injection servomotor 23. In the figure, symbol j is a drive signal for the plasticizing servo motor 13 output from the motor driver circuit 8, and symbol k is a drive signal for the injection servo motor 23 output from the motor driver circuit 8.

  Hereinafter, the operation program of the pre-plastic injection molding machine stored in the storage unit 53 of the control device 5 will be described with reference to FIG.

  When the system is activated, the arithmetic control unit 55 outputs a control signal f to the motor driver circuit 8 via the output unit 52, and the injection servo motor 23 is controlled by the motor drive signal k output from the motor driver circuit 8. Forward rotation is performed, and the injection plunger 22 is retracted to a predetermined retracted position stored in the storage unit 53 (step S1).

  At the stage where the injection plunger 22 has retracted to the predetermined retracted position, the arithmetic control unit 55 starts counting the time signal i output from the timer 54 (step S2).

  Next, the arithmetic control unit 55 outputs a control signal e to the motor driver circuit 8, rotates the plasticizing servo motor 13 in the forward direction by the motor drive signal j output from the motor driver circuit 8, and rotates the screw 12. Is started (step S3). As a result, the molding material supplied into the heating cylinder 11 from a hopper (not shown) is plasticized and kneaded by the heating of the heating cylinder 11 and the shearing force of the screw 12, and sequentially transferred to the front end side of the heating cylinder 11. The molding material that has reached the front end side of the heating cylinder 11 is supplied into the injection chamber 27 of the injection cylinder 21 through the molding material passage 4.

  Next, the arithmetic control unit 55 determines whether or not the timing signal i output from the timer 54 has reached a predetermined count number stored in the storage unit 53 (step S4), and has reached the predetermined count number. (Yes), it is determined that the injection chamber 27 is filled with a predetermined amount of molding material, and the process proceeds to step S5. In step S 5, the arithmetic control unit 55 outputs a control signal f to the motor driver circuit 8 via the output unit 52, and reverses the injection servomotor 23 by the motor drive signal k output from the motor driver circuit 8. The injection plunger 22 is rapidly advanced to a predetermined advance position stored in the storage unit 53. Since the filling amount of the molding material into the mold cavity 31 is the product of the cross-sectional area of the injection cylinder 21 and the movement amount of the injection plunger 22 from the retracted position to the advanced position, the molding material is measured in this step S5. And injection of the molding material into the mold cavity 31 can be performed simultaneously.

  After the measurement and injection of the molding material are completed, the process returns to step S1 and the above steps are repeated. When it is determined in step S4 that the timing signal i output from the timer 54 has not reached the predetermined count number stored in the storage unit 53 (No), the timing signal i output from the timer 54 is stored in the storage unit. The supply of the molding material to the injection chamber 27 is continued until the predetermined count number stored in 53 is reached.

  The pre-plastic injection molding machine of this example can close the molding material passage 4 by the injection plunger 22 at an early stage of the injection process by setting the retreat position of the injection plunger 22 in the vicinity of the molding material passage 4. At times, the pressure acting on the molding material passage 4 can be reduced. Therefore, it is not necessary to set a check ball valve for the molding material passage 4 or to form an injection sub-passage for the injection cylinder, which can simplify the molding machine and reduce the cost. It is possible to prevent the retention of the molding material generated by the provision, and it is possible to prevent the malfunction of the molding machine due to the deterioration of the molding material. Furthermore, since the molding material passage 4 can be arranged behind the front end of the injection plunger 22 at the completion of injection, the amount of molding material staying in the injection cylinder 21 can be reduced, and the molding material can be prevented from being burned. Thus, molding defects due to deterioration of the molding material can be prevented. In addition, after the injection chamber 27 is filled with the molding material, the injection plunger 22 is advanced to a predetermined advance position to meter the molding material injected into the mold cavity 31 and into the mold cavity 31. Since the molding material is injected, the molding material injected into the mold cavity 31 can be precisely measured by controlling the retreat position and the advance position of the injection plunger, and a high-quality molded product is obtained. Can be formed efficiently.

It is sectional drawing at the time of injection plunger retreat of the pre plastic type injection molding machine concerning an embodiment. It is sectional drawing which shows the filling state of the molding material in the injection chamber of the pre-plastic injection molding machine which concerns on embodiment. It is sectional drawing at the time of the injection plunger advance of the pre-plastic injection molding machine which concerns on embodiment. It is principal part sectional drawing which shows the resin pressure adjustment method of the plasticization chamber in the pre-plastic injection molding machine which concerns on embodiment. It is a block diagram of the control apparatus with which the pre-plastic injection molding machine which concerns on embodiment is equipped. It is a flowchart which shows operation | movement of the pre-plastic injection molding machine which concerns on embodiment. It is sectional drawing at the time of the measurement of the pre-plastic injection molding machine concerning a prior art example. It is sectional drawing at the time of the measurement of the in-line type injection molding machine concerning a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasticization part 2 Injection part 3 Molding material 4 Molding material channel | path 5 Control apparatus (control part)
6 Input Device 7 Display Device 8 Motor Driver Circuit 11 Heating Cylinder 12 Screw 13 Plasticizing Servo Motor 14 Rotation Detector 15 Plasticizing Chamber 21 Injection Cylinder 22 Injection Plunger 23 Injection Servo Motor 24 Rotation Detector 25 Ball Screw Mechanism 27 Injection Chamber 28 Injection hole 29 Nozzle 31 Mold cavity 33 Fixed mold 35 Movable mold

Claims (4)

A plasticizing part that plasticizes and kneads the molding material by rotating a screw in the heating cylinder, and a molding material that is plasticized and kneaded in the plasticizing part by advancing and retracting the injection plunger in the injection cylinder. An injection part that injects into the plastic part, a plasticizing chamber provided in the plasticizing part, a molding material passage that communicates the injection chamber provided in the injection part, and driving of the plasticizing part and the injection part In a pre-plastic injection molding machine equipped with a control unit,
After the injection of the molding material into the mold is completed, the control unit retracts the injection plunger to a position where the molding material passage is opened, and the molding material from the plasticizing chamber into the injection chamber After the molding material is filled in the injection chamber, the injection plunger is advanced to a predetermined advance position to measure the molding material injected into the mold and into the mold. The molding material is injected and the retraction position of the injection plunger is changed to adjust the opening of the molding material passage when the injection plunger is retracted, so that the molding material is kneaded in the plasticizing chamber. A pre-plastic injection molding machine characterized by controlling the state . The said control part controls the filling amount of the said molding material in the said metal mold | die by changing at least any one of the advance position of the said injection plunger, and a retreat position. Pre-plastic injection molding machine. In the process of moving the injection plunger from the retracted position to the advanced position , the control unit closes the molding material passage by the injection plunger and prevents the molding material from flowing back into the plasticizing chamber. 2. The pre-plastic injection molding machine according to claim 1, wherein The pre-plastic injection molding machine according to any one of claims 1 to 3, wherein a servo motor is used as a driving source of the injection plunger .

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