JPH05337993A - Continuous plasticizing injection molding method and apparatus - Google Patents

Abstract

PURPOSE:To accurately perform plasticization and injection molding in an apparatus wherein an accumulator device of a plasticized resin is interposed between a plasticizing device and an injection device. CONSTITUTION:The retreat speed of an injection plunger 32 is controlled in relation to the advance operation of the plunger 22 of an accumulator device 20 by a controller 71 so that the emitting pressure of a continuous plasticizing device 10 is received within a predetermined pressure range suitable for plasticization. Accompanied by this, the pressure in a weighing chamber 33 is also properly controlled to enable accurate injection molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous plasticizing injection molding method and apparatus which are carried out by an apparatus in which a continuous plasticizing apparatus and an injection apparatus are connected via an accumulator.

[0002]

2. Description of the Related Art In order to improve the efficiency of an injection molding machine, conventionally, a plasticizing device and an injection device are separated from each other, and an accumulator is provided between them to store the resin plasticized by the plasticizing device in the accumulator. There is a device which increases the operating rate of the plasticizing device by intermittently supplying the plasticizing resin from the accumulator to the injection device.

The inventors of the present invention have supplied the plasticizing resin from the plasticizing device to the injection device even when the plasticizing resin is being supplied from the accumulator to the injection device so that the plasticizing device can be operated completely continuously. We have proposed a continuous plasticization type injection molding machine (Japanese Patent Application No. 3-76821).

[0004]

In the above continuous plasticizing type injection molding apparatus, the injection plunger is retracted by the resin pressure from the accumulator and the plasticizing device in the measuring step of supplying the plasticizing resin from the accumulator to the injection device. However, in the measuring process, the discharge pressure of the plasticizing device tends to increase. This is compared with the process of simply storing the plasticized resin in the accumulator, and the resin pressure loss between the accumulator and the injection device is added, and
This is because the mechanical friction loss for retracting the injection plunger is added.

The fluctuation of the discharge pressure of the plasticizer causes uneven plasticization, and when the discharge pressure rises abnormally, venting occurs or resin leaks from the opening / closing valve or the joint of the resin flow path. In addition, the thrust load of the plasticizing screw becomes large, so that it becomes necessary to increase the rigidity of the screw driving device.

It is an object of the present invention to provide a continuous plasticizing type injection molding method and apparatus which can accurately perform plasticization in the above continuous plasticizing type injection molding apparatus.

[0007]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides an accumulator device comprising a continuous plasticizer for synthetic resin material, and a cylinder and a plunger connected to the outflow passage of the continuous plasticizer. And an injection device including an injection cylinder and an injection plunger connected to the outflow passage of the accumulator device via an opening / closing valve, and the outflow passage of the continuous plasticizing device has the plunger of the accumulator device at the extrusion limit position. A continuous plasticizing injection molding method using a continuous plasticizing injection molding device configured to be able to communicate with the outflow passage of the accumulator device even when the plunger of the accumulator device is moved forward while the injection plunger is retracted. In the metering process in which a specified amount of plasticized resin is introduced into the To keep within, some retraction rate of the injection plunger, in order to control the value determined pre Ji because in correspondence with the forward and stop movement of the plunger of the accumulator device.

Further, according to the present invention, in order to carry out the above-mentioned method, the retraction speed control operation section of the injection plunger, the operation detection section of the plunger of the accumulator device, and the retraction speed control operation section by the signal from the operation detection section. A continuous plasticizing type injection molding apparatus provided with a control section for giving a speed command signal set in advance.

In order to achieve the above object, the present invention detects the discharge pressure of a continuous plasticizing device and controls the backward movement speed of the injection plunger and the plunger of the accumulator device according to the discharge pressure. Type injection molding method, and in order to carry out this method, signals from the injection plunger and the retreat speed control operation unit of the plunger of the accumulator device, the discharge pressure detection unit of the continuous plasticizer, and the discharge pressure detection unit are collected. A continuous plasticizing type injection molding apparatus is provided with a control section for operating the retreat speed control operation section so as to keep the discharge pressure at a desired value.

In this case, it is preferable that a retreat speed control operation unit for the plunger of the accumulator device is added and the retreat speed of the plunger of the accumulator device can be controlled by the control unit.

[0011]

In the measuring process, the ejection pressure of the continuous plasticizer is set to a predetermined value by positively retracting the injection plunger at a speed corresponding to the advance / stop operation of the plunger of the accumulator device or the discharge pressure of the continuous plasticizer. Kept within range. As a result, the plasticization by the continuous plasticizer is stably and accurately performed, venting does not occur, and the pressure in the measuring chamber is maintained at an appropriate level, so that more accurate measuring is performed.

[0012]

Embodiments of the present invention will be described below with reference to FIGS.
Will be described. Reference numeral 10 denotes a continuous plasticizing device, which comprises a plasticizing cylinder 11 having a heating and cooling device (not shown) and a plasticizing screw 12 engaged with the plasticizing cylinder 11. The plasticizing screw 12 is a biaxial screw that rotates in the same direction or in different directions, and is given only rotation by the drive device 13. A first supply port 14 is opened near the base end of the plasticizing cylinder 11, and a synthetic resin material is supplied by the first feeder 15. A second supply port 16 is opened at a substantially central position of the plasticizing cylinder 11 in FIG. 1, and a reinforcing or filling material such as glass fiber, carbon fiber and mica is supplied by the second feeder 17. ing. A vent port 18 is opened to the left of the plasticizing cylinder 11 in FIG.

An outflow path 19 for the plasticizing resin opened at the tip of the plasticizing cylinder 11 is connected to an accumulator device 20. The accumulator device 20 is composed of a cylinder 21 and a plunger 22, and an accumulator chamber 23 is provided on the tip side (the lower end side in FIG. 1) of the plunger 22.
Is formed. The periphery of the accumulator chamber 23 is heated by a heater (not shown). A piston 26 of a drive cylinder 25 is connected to the upper end of the plunger 22 via a rod 23.

When the plunger 22 is located at the forward limit position shown in FIG. 1, the accumulator chamber 23 has an annular flow path 23a due to the small diameter projection 22a at the tip and the inner surface of the cylinder 21.
Are formed. Further, the step portion 22b formed at the base of the small-diameter projection portion 22a of the plunger 22 is
The side facing the outflow passage 19 of the continuous plasticizer 10 is high,
When the plunger 22 is formed in an inclined manner so that the opposite side becomes low, and the plunger 22 is at the forward limit position, the outflow passage 19 has the step portion 2
It is arranged so as to open below the highest position of 2b, that is, at the upper end of the annular flow path 23a.

The annular flow path 23a is formed so as to change the cross-sectional area of the flow path from the outflow path 19 to the outflow path 27 of the accumulator device 20 opened at the lower end of the cylinder 21 as smoothly as possible. The annular flow path 23a is
By appropriately forming the tip shape of the plunger 22, a flow path between the outflow passages 19 and 27 which is as close to a straight line as possible and has a constant cross-sectional area may be formed.

Outflow passage 27 of accumulator device 20
Is connected to the injection device 30 via the first opening / closing valve 28. The injection device 30 includes an injection cylinder 31 that is heated by a heater (not shown) and an injection plunger 32 that is engaged with the injection cylinder 31. The plasticizing resin supplied from the accumulator chamber 23 is supplied to the tip side of the injection plunger 32 (in FIG. 1). It is designed to be stored in the measuring chamber 33 on the left end side. A piston 36 of an injection drive cylinder 35 is connected to the rear end of the injection plunger 32 via a rod 34. The measuring chamber 33 is connected to the nozzle 38 via a second opening / closing valve 37.

The upper chamber 25a of the drive cylinder 25 of the accumulator device 20 includes a tank 44 and a meter-in first flow rate adjusting valve 42 and a counter balance valve 43 when the first switching valve 41 is in the neutral position shown in the drawing. Lower chamber 25b
And the pressure in the upper chamber 25a is connected to the counter balance valve 4
When the pressure exceeds the set pressure of 3, the pressure oil in the upper chamber 25a is released to the tank 44, and when the first switching valve 41 is switched to the right side b in FIG. The pressure oil controlled to have a predetermined pressure is supplied via the first flow rate adjusting valve 42. The lower chamber 25b is opened to the tank 44 when the first switching valve 41 is switched to the b side, and is connected to the hydraulic pressure source 45 via the first pressure reducing valve 46 when the first switching valve 41 is switched to the a side. It is supposed to be done. The on-off valve 47 is the plunger 2
This is for temporarily stopping the forward movement of No. 2.

The rear chamber 35a of the injection drive cylinder 35 is connected to the tank 53 via the electromagnetic relief valve 52 when the second switching valve 51 is in the illustrated neutral position and the switching position on the side a. The electromagnetic relief valve 52 controls the logic valve 52b by the set pressure of the pressure setting relief valve 52c when the switching valve 52a is in the switching position shown in the drawing, and when the switching valve 52a is switched to the b side opposite to that shown in the drawing. The logic valve 52b is blocked. Further, in the rear chamber 35a, when the second switching valve 51 is switched to the b side, the second pressure reducing valve 54
Is connected to the hydraulic power source 55 via the.

In the front chamber 35b, when the second switching valve 51 is in the switching position on the side a, an electromagnetic proportional flow rate adjusting valve 56 as a backward speed control operation portion of the injection plunger 32 and the second pressure reducing valve 54 are interposed. Is connected to the hydraulic power source 55. A pressure gauge 58 is connected to the rear chamber 35a via a stop valve 57.

A resin pressure switch 6 is provided in each of the outflow passage 19 of the continuous plasticizer 10 and the position near the tip of the measuring chamber 33.
1, 62 are connected, and when the resin pressure of both parts reaches a predetermined value described later, the contacts are closed to generate a signal.

The accumulator device 20 includes detectors 63 and 64 for detecting the backward limit position and the forward limit position of the plunger 22 and a detector 65 for detecting that the plunger 22 is slightly retracted from the forward limit position. And are provided.

The injection device 30 is provided with a detector 66 for detecting the measuring position of the injection plunger 32. The detector 66 is mounted so that its position can be adjusted so as to determine the measurement completion position of the injection plunger 32 according to the amount of resin of the injection-molded product.

67 is a sequencer, and the plunger 22
Is operated by a signal from a detector 64 which detects the forward limit position of the electromagnetic proportional flow rate adjusting valve 56.

FIG. 2 shows the relationship between the plasticized resin discharge flow rate Q1 of the continuous plasticizer 10 and the plasticized resin discharge flow rate Q2 of the accumulator device 20, and the operation of the plunger 22 and the injection plunger 32. The discharge flow rate Q2 of the accumulator device 20 is a flow rate discharged from the accumulator chamber 23 toward the measuring chamber 33 when the plunger 22 is advanced at a predetermined speed, as indicated by a straight line A1 in the middle of FIG. ..

Therefore, when the plunger 22 moves forward as shown by the straight line A1, both discharge flow rates Q to the measuring chamber 33.
When the total flow rate Q of 1 and Q2 flows in and the plunger 22 reaches the forward limit and stops, only the discharge flow rate Q1 of the continuous plasticizing device 10 flows into the measuring chamber 33.

Therefore, the set speed parameter of the controller 68 is a speed V which is substantially proportional to the flow rates Q and Q1 before and after the plunger 22 reaches the forward limit position.
It is set to retract the injection plunger 32 by 1 and V2.

Next, the continuous plasticizing injection molding method using this apparatus will be described. The first feeder 15 quantitatively supplies a synthetic resin material such as polypropylene from the first supply port 14 of the biaxial screw type continuous plasticizing device 10 which is preferably rotating in the same direction, and the biaxial plasticizing screw 1
2. Plasticize and knead. The second from the second supply port 16
For example, glass fiber which is a reinforcing material or a filling material is supplied by a feeder 17 at a total weight ratio of about 10 to 60%, mixed with a synthetic resin material which is plasticized and sent, and degassed (vacuum suction) at a vent port 18. ) And extrude from the outflow path 19. At this time, since the biaxial plasticizing screw 12 is rotating at a constant position, the plasticizing is performed under substantially constant conditions.

Now, assuming that it is a storage step of storing the plasticized resin extruded from the outflow passage 19 at the discharge flow rate Q1 in the accumulator device 20, the first opening / closing valve 28 is closed and the first switching valve 41 is illustrated. It is placed in a neutral position. Therefore, the plasticized resin extruded from the outflow passage 19 is
As indicated by a straight line A2 in FIG. 2, the plunger 22 is pushed up, the pressure oil in the upper chamber 25a is released to the tank 44 through the counter balance valve 43 and the first switching valve 41, and the plunger 22 is raised at a predetermined pressure. Let the accumulator room 23
Is expanded and accumulated in it. The set pressure of the counter balance valve 43 is determined so that the pressure for raising the plunger 22, that is, the discharge pressure of the continuous plasticizing device 10 becomes a pressure suitable for plasticizing.

During the above accumulation process, the injection plunger 32
Performs an injection and pressure holding process as shown in the lower part of FIG. When this pressure holding step is completed, the second opening / closing valve 37 is closed and the first opening / closing valve 28 is opened. By this time, the plunger 22 of the accumulator device 20 has risen by a predetermined amount and accumulates in the accumulator chamber 23 an amount of plasticized resin that is less than the injection amount of one time.

After opening the first opening / closing valve 28, the first switching valve 41 is switched from the neutral position in the figure to the right side b side position,
The pressure oil controlled from the hydraulic pressure source 45 to the predetermined pressure and the predetermined flow rate by the first pressure reducing valve 46 and the first flow rate adjusting valve 42 is supplied to the upper chamber 25a.
Supply to. As a result, the plunger 22 descends at a predetermined speed, as indicated by the straight line A1 in FIG.

Simultaneously with the switching of the first switching valve 41, the second switching valve 51 is switched to the left side "a" position, and the hydraulic pressure source 55 and the second pressure reducing valve 54 are electromagnetically proportional to the front chamber 35b of the injection drive cylinder 35. Pressure oil controlled to a predetermined pressure and a predetermined flow rate by the flow rate adjusting valve 56 is supplied. This causes the piston 36 to
The pressure oil in the rear chamber 35a is discharged to the tank 53 while maintaining a predetermined pressure by the electromagnetic relief valve 52, and the injection plunger 32 is retracted at a predetermined speed V1.

The retreat speed V1 of the injection plunger 32 is set by the controller 68 in relation to the total flow rate Q of the plasticizing resin from the continuous plasticizer 10 and the accumulator device 20 as described above. 1
The discharge pressure of 0 is kept within a predetermined range that does not cause a problem in plasticization. That is, when the discharge pressure becomes too high, venting up from the vent port 18 occurs, so at least the upper limit pressure that does not cause venting up and the lower limit pressure that does not cause insufficient plasticization / kneading. The injection plunger 32 is retracted to a suitable pressure in between.

By controlling the discharge pressure as described above, the plasticization by the continuous plasticizing device 10 is smoothly performed. Thus, when the plunger 22 reaches the forward limit, the detector 64 is closed and the detection signal is sent to the sequencer 67. At this time, the first switching valve 41 remains switched to the b side.

When the plunger 22 is stopped, no plasticizing resin is discharged from the accumulator chamber 23 to the measuring chamber 33, and the flow rate Q1 discharged from the continuous plasticizing device 10 is eliminated.
Only the plasticized resin of (3) flows into the measuring chamber 33 through the annular flow path 23a forming a part of the accumulator chamber 23. Then, the sequencer 67 uses the detector 64
The signal set from the injection plunger 3 changes the set flow rate of the electromagnetic proportional flow rate adjustment valve 56 to a value according to the discharge flow rate Q1.
2 is retracted to the metering completion position detected by the detector 66 at the above-described retreat speed V2 to maintain the discharge pressure at a suitable value and the pressure in the metering chamber 33 appropriately.

FIG. 3 shows another embodiment of the present invention. A resin pressure detector 70 is provided in place of the resin pressure switch 61 shown in FIG. 1 to detect the discharge pressure of the continuous plasticizer 10. The electromagnetic proportional flow rate adjusting valve 56 is operated so that the discharge pressure becomes a set value set in the setting device 72.

According to the embodiment of FIG. 3, the discharge pressure of the continuous plasticizing apparatus 10 can be controlled more accurately as compared with the embodiment of FIG.

Further, in FIG. 3, an electromagnetic proportional pressure adjusting valve 73 is provided in place of the counter balance valve 43 of FIG. 1, and the controller 71 sets the electromagnetic proportional pressure adjusting valve 73 in the accumulation process to the accumulator device 20. By adjusting the pressure and controlling the back pressure of the plunger 22, the retreat speed of the plunger 22 is controlled, and the discharge pressure of the continuous plasticizing device 10 is controlled to a predetermined value even in the accumulation step.

In the embodiment described above, the injection plunger 32
Although the example in which the electromagnetic proportional flow rate adjusting valve 56 is used to control the reverse speed of the above is shown, the invention is not limited to this, and the discharge flow rate itself from the hydraulic pressure source 55 is controlled by using an electronic variable pump or the like as the hydraulic pressure source 55. You may do it.

Further, in the above-mentioned embodiment, the retreat speed of the injection plunger 32 is set to the front chamber 35 of the injection drive cylinder 35.
Although an example in which the flow rate of the pressure oil supplied to b is controlled is shown, the pressure may be controlled in the rear chamber 35a.
Needless to say, it is more preferable to control the retreat speed of No. 2 by the same flow rate control method as that of the injection plunger 32, and to appropriately control the advancing speed of the plunger 22 in the measuring process.

Furthermore, the present invention can be applied not only to the hydraulic drive system but also to an electric drive system device.

[0041]

As described above, according to the present invention, the discharge pressure of the continuous plasticizing device can be maintained within a desired range for proper plasticization, and proper weighing can be performed. Therefore, it is possible to obtain the effect that the injection molding can be performed accurately.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing discharge flow rates Q1 and Q2 from a continuous plasticizing device and an accumulator device in the device of FIG. 1, and operating states of a plunger and an injection plunger.

FIG. 3 is a schematic configuration diagram showing another embodiment of the present invention.

[Explanation of symbols]

 10 Continuous Plasticizing Device 11 Plasticizing Cylinder 12 Plasticizing Screw 13 Driving Device 14 First Supply Port 15 First Feeder 16 Second Supply Port 17 Second Feeder 18 Vent Port 19 Outflow Path 20 Accumulator Device 21 Cylinder 22 Plunger 23 Accumulator Chamber 23a Annular flow path 25 Drive cylinder 27 Outflow path 28 First opening / closing valve 30 Injection device 31 Injection cylinder 32 Injection plunger 33 Measuring chamber 35 Injection drive cylinder 37 Second opening / closing valve 38 Nozzle 41 First switching valve 42 First flow rate adjusting valve 43 Counter balance valve 46 First pressure reducing valve 51 Second switching valve 52 Electromagnetic relief valve 54 Second pressure reducing valve 56 Electromagnetic proportional flow rate adjusting valve 61,62 Resin pressure switch 63,64,65,66 Detector 67 Sequencer 68,71 Controller 70 Resin pressure Can 72 setter 73 electromagnetic proportional pressure control valve

Claims (6)

[Claims] 1. An accumulator device comprising a continuous plasticizing device for synthetic resin material, a cylinder and a plunger connected to an outflow passage of the continuous plasticizing device, and an outflow passage of the accumulator device connected via an opening / closing valve. An injection device including an injection cylinder and an injection plunger, and the outflow passage of the continuous plasticizing device can communicate with the outflow passage of the accumulator device even when the plunger of the accumulator device is in the extrusion limit position. A continuous plasticization type injection molding method using a configured continuous plasticization type injection molding apparatus, wherein a predetermined amount of plasticized resin flows into the injection cylinder by retracting the injection plunger while advancing the plunger of the accumulator device. In the measuring step, the discharge pressure of the continuous plasticizing device is kept within a predetermined range. The retraction speed of the injection plunger, continuous plasticizing type injection molding method characterized by controlling a value that defines pre Ji because in correspondence with the forward and stop movement of the plunger of the accumulator device. 2. An accumulator device comprising a continuous plasticizing device for a synthetic resin material, a cylinder and a plunger connected to an outflow passage of the continuous plasticizing device, and an outflow passage of the accumulator device connected via an opening / closing valve. An injection device comprising an injection cylinder and an injection plunger, wherein the outflow passage of the continuous plasticizing device can communicate with the outflow passage of the accumulator device even when the plunger of the accumulator device is in the extrusion limit position. A configured continuous plasticizing injection molding device, wherein the retraction speed control operation part of the injection plunger, the plunger motion detection part of the accumulator device, and the retraction speed control operation part by a signal from the motion detection part. And a controller for giving a speed command signal preset to the continuous plasticizer. Wherein the injection molding apparatus. 3. An accumulator device comprising a continuous plasticizing device for synthetic resin material, a cylinder and a plunger connected to an outflow passage of the continuous plasticizing device, and an outflow passage of the accumulator device connected via an opening / closing valve. An injection device including an injection cylinder and an injection plunger, and the outflow passage of the continuous plasticizing device can communicate with the outflow passage of the accumulator device even when the plunger of the accumulator device is in the extrusion limit position. A continuous plasticization type injection molding method using a configured continuous plasticization type injection molding apparatus, wherein a predetermined amount of plasticized resin flows into the injection cylinder by retracting the injection plunger while advancing the plunger of the accumulator device. In the measuring step, the discharge pressure of the continuous plasticizing device is kept within a predetermined range. Detecting the discharge pressure of the continuous plasticator, continuous plasticizing type injection molding method characterized by controlling the retracting speed of the injection plunger according to said discharge discharge pressure. 4. The continuous plasticizing injection according to claim 3, wherein in the step of storing the plasticizing resin in the cylinder of the accumulator device, the retreating speed of the plunger of the accumulator device is controlled according to the discharge pressure. Molding method. 5. An accumulator device comprising a continuous plasticizing device for synthetic resin material, a cylinder and a plunger connected to an outflow passage of the continuous plasticizing device, and an outflow passage of the accumulator device connected via an opening / closing valve. An injection device comprising an injection cylinder and an injection plunger, wherein the outflow passage of the continuous plasticizing device can communicate with the outflow passage of the accumulator device even when the plunger of the accumulator device is in the extrusion limit position. A continuous plasticization type injection molding apparatus configured, comprising: a retraction speed control operation section of the injection plunger, a discharge pressure detection section of the continuous plasticization apparatus, and a signal from the discharge pressure detection section. A continuous plasticizing injection molding machine, comprising: a control unit that operates the retreat speed control operation unit so as to maintain the discharge pressure at a desired value. . 6. The continuous plasticizing system according to claim 5, wherein a retreat speed control operation unit for the plunger of the accumulator device is added, and the retreat speed of the plunger of the accumulator device is also controllable by the control unit. Injection molding equipment.