JPH0596570A - Injection molding method and device therefor - Google Patents

Abstract

(57) [Summary] [Purpose] To enable injection molding with the heat history of the molding material reduced. [Structure] A molten material melted and kneaded and extruded from a twin-screw extruder 40 is supplied to an injection cylinder 14 of an injection device 10 through a bendable pipe 20, and then the supplied molten material of the injection device is supplied. The measurement is performed in the injection cylinder, the supply of the molten material is stopped at the same time when the measurement is completed, and then the measured molten material is injected into the clamped mold cavity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding method and apparatus.

[0002]

2. Description of the Related Art A conventional resin molding device is shown in FIG. In the resin molding apparatus shown in this figure, the molten resin extruded from the extruder 100 is
It is adapted to be supplied between the molds 106 of the opened press 104 through 02. The extruder 100 is XY
The press 104 is mounted on the table 108.
It is movable relative to. The powdery or granular resin material supplied from the feeder 110 into the extruder 100 is melted and kneaded in the extruder 100 and is extruded into the mold 106 through the pipe 102 as the molten resin as described above. Is becoming After supplying the molten resin, the pipe 102 is retracted from between the molds 106. Press molding is performed by closing and clamping the mold 106. As a result, a resin molded product can be obtained.

[0003]

However, in the conventional resin molding apparatus as described above, the surface portion of the molten resin supplied onto the mold comes into contact with the outside air until the mold is closed, and Since the temperature of the molten resin becomes non-uniform due to contact with the mold, flow marks are likely to occur and it is difficult to obtain a molded product of high quality. As a solution to this problem, there is an injection molding method in which molten resin is injected all at once into a clamped mold,
It is effective in preventing partial cooling of the molten resin.
However, in the injection molding method, pellets used in advance by a resin maker have been used in which a granular resin raw material is sufficiently melted and kneaded by a twin-screw extruder or the like to obtain a uniform mixing ratio and granulated by a granulator. .. This is because the screw of the injection device is uniaxial and the ratio of the screw diameter to the screw length (usually referred to as “L / D”) is designed to be small, so that a powdery or granular resin raw material is used. This is because even if it is supplied as it is, it cannot be sufficiently melted and kneaded. For this reason, the above pellets are used as the resin material, but there is a problem that energy loss due to reheating the pellets that have been melted by heating and granulated cannot be avoided. Further, there has been a problem that the heat history of the resin material increases with reheating and the physical properties of the molding material deteriorate due to excessive kneading. The present invention aims to solve such problems.

[0004]

According to the present invention, a molten resin melted and kneaded by a twin-screw extruder is supplied to an injection device through a pipe member configured to be deformable, and after measuring the molten resin in the injection device, The above problem is solved by injecting into the mold cavity. That is, claim 1 of the present invention
In the injection molding method corresponding to, the molten material melted and kneaded in the twin-screw extruder and extruded from this is supplied to the injection device of the injection molding machine through a bendable pipe, and then the supplied molten material is supplied. The measurement is performed by the injection device, the supply of the molten material is stopped at the same time when the measurement is completed, and then the measured molten material is injected into the cavity of the clamped mold. Further, in the injection molding method according to claim 2 of the present invention, the molten material melted and kneaded in the twin-screw extruder and extruded from this is supplied to the accumulator of the injection molding machine through a bendable pipe. The molten material is supplied from the accumulator to the injection device, the molten material is also supplied from the twin-screw extruder to the injection device by bypassing the accumulator, and the supplied molten material is measured in the injection device. The supply of the molten material to the injection molding machine is stopped, and then the measured molten material is injected into the cavity of the clamped mold. An apparatus according to claim 3 of the present invention has an injection device (10) and a mold clamping device (30), and molds molten material measured by an injection cylinder (14) of the injection device. The target is to inject into the cavity of the mold (32/34) installed in the device, and the twin screw extruder (4
0), a vent member (12), and a bendable pipe (20) for communicating between the twin-screw extruder and the vent member, and the vent member allows the pipe and the injection cylinder to communicate with each other. A vent passage (12a) and a discharge passage (12b) communicating with the injection cylinder and the outside of the injection cylinder are formed. A device according to claim 4 of the present invention is a twin-screw extruder (40) and a vent member (70).
And a bendable pipe (20) for communicating between the twin-screw extruder and the vent member, and the vent member (70b) for communicating the injection cylinder and the pipe with the vent member.
And an accumulation chamber (70a) communicating with the vent passage
A discharge passage (70c) for communicating the injection cylinder with the outside of the injection cylinder, and a piston (72) fitted in the accumulation chamber, and a piston drive device (76) for driving the piston, A passage opening / closing valve (78) inserted into a vent passage portion of the vent member on the injection cylinder side is provided. A plurality of injection devices may be provided, and a passage switching valve (58) for switching the communication state may be provided in the pipe that connects the twin-screw extruder and each injection device. Further, an auxiliary pump (54) for feeding the molten material under pressure may be provided between the twin-screw extruder and the pipe. The reference numerals in parentheses indicate the corresponding members of the embodiment.

[0005]

[Action]

(Operation of Claim 3) When the molten material extruded from the twin-screw extruder is supplied to the injection device, the passage communicating between the hopper and the injection cylinder mounted on the injection device is blocked. The molten material supplied from the axial extruder through the pipe and the vent passage of the vent member to the injection device is immediately measured by the injection cylinder. As a result, the molten material extruded from the twin-screw extruder can be directly injection-molded into a molded product without forming a pellet. When supplying the raw materials from the hopper to the injection cylinder, open the passage that connects the hopper and the injection cylinder mounted on the injection device, and melt and knead the raw material supplied from the hopper by the injection cylinder. After forming the material, the molten material is weighed. This allows the normal operation of the injection molding machine to be performed. (Operation of Claim 4) When the molten material extruded from the twin-screw extruder is supplied to the injection device, the passage communicating between the hopper and the injection cylinder mounted on the injection device is blocked. The molten material extruded from the axial extruder is stored in the accumulation chamber through the pipe and the vent passage of the vent member. Next, the molten material extruded from this and the molten material extruded from the twin-screw extruder and bypassing the accumulation chamber are merged and supplied to the injection cylinder, and immediately measured by the injection cylinder. As a result, the measuring time can be shortened, and the molten material extruded from the twin-screw extruder can be directly injection-molded into a molded product without being pelletized.

[0006]

【Example】

(First Embodiment) FIGS. 1 to 4 show a first embodiment of the present invention.
The injection cylinder 14 of the injection device 10 has a cylinder hole 14
a and the nozzle 14b are formed. Injection cylinder 1
A screw 16 is rotatably and axially movably fitted to the screw 4 (see FIG. 2), and a vent member 12 and a hopper 18 are attached to the screw 4. As shown in FIG. 4, the vent member 12 has a vent passage 12a and a discharge passage 12b. The vent passage 12a and the discharge passage 12b are provided in the cylinder hole 1 of the injection cylinder 14.
4a and 4a, respectively. One end of the melt tube 20 is connected to the vent member 12 so as to communicate with the vent passage 12a, and a discharge pipe 22 is connected so as to communicate with the discharge passage 12b. The melt tube 20 is formed in the shape of a pipe, and the 3
As shown in FIG. 3, swivel joints 24 are inserted in the respective places. This makes it possible to change the relative positions of the one end and the other end of the melt tube 20 in which the swivel joint 24 is incorporated. The other end of the melt tube 20 is a third swivel joint 2 arranged on the extrusion port 40a side of a twin-screw extruder 40 described later.
It is connected with 4. A valve 26 is inserted in the discharge pipe 22. The valve 26 is a manual pressure control valve and can discharge the gas separated from the molten resin and the excessively supplied molten resin to the outside through the discharge pipe 22. The outer surfaces of the vent member 12, the discharge passage 12b, the injection cylinder 14, the melt tube 20, the discharge pipe 22 and the like are covered with a heater 28, respectively.

The mold clamping device 3 is located on the left side of the injection device 10 in FIG.
0 is placed. A mold clamping cylinder (not shown) of the mold clamping device 30 can open and close the mold 32 and the mold 34.
The above-mentioned injection device 10 is entirely movable in the axial direction as shown in FIG. 3, and its nozzle 14b is pressed against the resin injection port 30a of the mold clamping device 30 at the forward position. In this state, the injection device 10 can inject the molten resin from the nozzle 14b of the injection device 10 through the resin injection port 30a of the mold clamping device 30 into the cavities of the molds 32 and 34 which are clamped.

A twin-screw extruder 40 is arranged on the right side of the injection device 10 in FIG. In this embodiment, the twin-screw extruder 40 is provided with two raw material supply ports, to which hoppers 42 and 44 are attached. Hopper 42
Two feeders 46 and 48 are attached to the. A feeder 50 is attached to the hopper 44. The feeders 46, 48, and 50 can supply different raw materials to the twin-screw extruder 40, respectively. Twin screw extruder 40
A switching valve 52 is attached to the extrusion port 40a. The switching valve 52 includes a supply port 52a and a discharge port 52.
b is formed. Supply port 52a of switching valve 52
Is connected to the above-mentioned melt tube 20 via a gear pump 54 and a swivel joint 24 as shown in FIG. The switching valve 52 can switch and communicate the extrusion port 40a of the twin-screw extruder 40 with either the supply port 52a or the discharge port 52b. Extrusion port 40 of twin-screw extruder 40
When a is switched to a position where it communicates with the discharge port 52b of the switching valve 52, the molten resin can be discharged from the discharge port 52b. The gear pump 54 is provided to prevent the flow rate of the molten resin extruded from the twin-screw extruder 40 from decreasing due to the conduit resistance of the melt tube 20 or the like. The pelletized resin material can be supplied from the hopper 18 into the cylinder hole 14a of the injection cylinder 14 described above, and the resin material can be melted and kneaded in the injection cylinder 14 to form a molten resin. , The pellet supply port of the hopper 18 is closed to stop the pellet supply, and instead, the molten resin extruded from the twin-screw extruder 40 is directly introduced into the cylinder hole 14a through the melt tube 20, the vent member 12, and the like. It is also possible to supply.

Next, the operation of the first embodiment will be described in the case of molding a modified nylon (nylon / PPO type) molded product. First, the pellet supply port of the hopper 18 attached to the injection device 10 is closed. In addition, the switching valve 52 has a discharge port 52b which has a twin-screw extruder 40.
It is switched to a position communicating with the extrusion port 40a. Then 2
The polyolefin resin (raw material A) is fed from the feeder 46 of the axial extruder 40, the organic acid compatibilizer (raw material B) is fed from the feeder 48 to the twin-screw extruder 40 through the hopper 42, and the nylon 50 is fed from the feeder 50. The raw material C) is supplied to the twin-screw extruder 40 through the hopper 44. When the twin-screw extruder 40 is driven, the raw material A and the raw material B are first kneaded and dispersed to produce a modified polyolefin, and then nylon is joined to the modified polyolefin and melted and kneaded to produce a predetermined modified nylon. The molten resin extruded from the twin-screw extruder 40 contains unkneaded resin until the physical properties of the modified nylon produced are stabilized, but these are discharged to the outside from the discharge port 52b. When the physical properties of the modified nylon are stabilized, the switching valve 52 is switched to connect the supply port 52a to the extrusion port 40a of the twin-screw extruder 40.
As a result, the modified nylon in the molten state passes through the extrusion port 40a, the switching valve 52, the gear pump 54, the swivel joint 24, the melt tube 20, and the vent passage 12a of the vent member 12 into the cylinder hole 14 of the injection cylinder 14.
extruded into a. At the same time, the injection device 10 is driven and the screw 16 is rotated. However, in this case, the melting / kneading process by the screw 16 is not performed, and the measuring operation is immediately performed to supply a predetermined amount of molten resin to the nozzle 14b.
Store in a nearby storage room. The gas separated from the molten resin is discharged to the outside through the discharge passage 12b, the valve 26 and the discharge pipe 22. When the weighing process is completed, the completion signal is output to the twin-screw extruder 40 and the twin-screw extruder 4
0, the feeders 46, 48 and 50 are temporarily stopped. This also stops the extrusion of the molten resin. If the molten resin is supplied even after the measurement process is completed, the pressure in the discharge passage 12b becomes high. Therefore, by opening the valve 26, the excess molten resin is discharged to the outside from the discharge pipe 22 through the valve 26. It Next, the mold clamping process of the mold clamping device 30 is started, and the molds 32 and 34 are closed and clamped. Subsequently, the nozzle 14b of the injection cylinder 14 is pressed against the resin supply port 30a of the mold clamping device 30 by advancing the entire injection device 10. At this time, the twin-screw extruder 40
Although the relative position of the injection device 10 changes with respect to, the melt tube 20 moves from the position shown by the phantom line in FIG. 3 to the position shown by the solid line in FIG. 3, and follows this. In this state, the displacement of the melt tube 20 is absorbed by the twisting operation of each swivel joint 24.
No excessive force acts on 0. Next, the injection device 10
Injection process is performed and a predetermined amount of molten resin is discharged to the nozzle 14b.
It is injected through the cavity into the cavities of the molds 32 and 34.
While the pressure holding / cooling step is being performed, the next measuring step is performed in the same manner as above. After completion of the cooling process, the injection device 1
0 is retracted, the mold is opened, and the molded product 56 is taken out. The mold is closed at the end of the measuring step, and the next injection, pressure holding and cooling steps are performed in the same manner as above. By repeating the above steps, the molded product 56 can be repeatedly molded. On the other hand, depending on the material used,
Since it may be necessary to use pellets, in such a case, the twin-screw extruder 40, the gear pump 54, etc. are stopped, and the pellet supply port of the hopper 18 attached to the injection device 10 is opened to start injection. The pellets are supplied into the cylinder 14 to operate as a normal injection device. That is, the pellet feeding by the injection device 10,
Melting / kneading operations are performed, and weighing, injection, pressure holding / cooling steps, and the like are sequentially performed.

(Second Embodiment) FIG. 5 shows a second embodiment of the present invention. The difference of the second embodiment from the first embodiment is that two injection devices 10 and two mold clamping devices 30 are provided, and in response to this, the molten resin extruded from the twin-screw extruder 40 is injected into each. A passage switching valve 58 for switching and supplying to the devices 10a and 10b is provided, and the melt tube 20 is connected so as to connect each injection device 10a, 10b and each switching port of the passage switching valve 58. Is. Mold clamping devices 30a and 30b are arranged corresponding to the respective injection devices 10a and 10b. In addition,
The same members as those used in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. FIG. 6 shows a control block. The integrated controller 60 is a controller 6 for the twin-screw extruder 40.
2. The control unit 64 of each injection molding machine 10a, 10b is integrally controlled. That is, the integrated control device 60 commands each of the injection molding machines 10a and 10b to have a molding timing shifted by a half cycle from each other, and the passage switching valve 5 corresponding thereto is commanded.
It is possible to control the switching timing of No. 8 and the rotation speed of the twin-screw extruder 40 so as to obtain a predetermined extrusion amount. The integrated control device 60 can control the switching of the switching valve 52 at the beginning of the operation. Control device 6
2 can output a control signal to the control mechanism 66 based on a command from the integrated control device 60. The control mechanism 66 can control the number of rotations of each of the feeders 46, 48 and 50 according to the control signal of the control device 62. The control device 64 controls each injection device 10 based on a command from the integrated control device 60.
a, 10b weighing, injection, pressure holding / cooling process, mold clamping device 3
It is possible to control the opening and closing of 0a and 30b.

Next, the operation of the second embodiment will be described.
The integrated control device 60 includes an injection device 10a and an injection device 10b.
Control so as to be shifted by a half cycle from each other, and control the switching of the passage switching valve 58 in synchronism with this. For example, the metering process is performed while the molten resin is being supplied from the twin-screw extruder 40 to the one injection device 10a, and at the same time, the pressure holding / cooling process is performed by the other injection device 10b. This allows
It is possible to continuously drive the twin-screw extruder 40 and the like at a constant speed without decelerating or stopping. Other operations are similar to those of the first embodiment.

(Third Embodiment) FIG. 7 shows a third embodiment of the present invention. The vent member 70 has an accumulation chamber 70a.
Is formed, and the piston 72 is fitted to this. The piston rod 74 of the piston 72 is connected to a piston drive device 76. The vent member 70 includes
A vent passage 70b and a discharge passage 70c are formed. The vent passage 70b communicates with the accumulation chamber 70a and the cylinder hole 14a of the injection cylinder 14, respectively. The vent member 70 is provided with a passage opening / closing valve 78 in a vent passage 70b portion on the injection cylinder 14 side. In the state where the passage opening / closing valve 78 is closed, the accumulating chamber 70a is connected to the twin-screw extruder 4 through the vent passage 70b.
The molten resin supplied from 0 (not shown in FIG. 7) can be stored. When the passage opening / closing valve 78 is opened, the piston 72 is driven by the piston drive device 76 to push the molten resin in the accumulation chamber 70 a into the injection cylinder 14. The other members that are the same as those in the first embodiment are designated by the same reference numerals as those in the first embodiment, and description thereof will be omitted.

Next, the operation of the third embodiment will be described.
With the passage opening / closing valve 78 closed, the molten resin extruded from the twin-screw extruder 40 is temporarily stored in the accumulation chamber 70a via the vent passage 70b. When a predetermined amount of molten resin is stored in the accumulation chamber 70a, the passage opening / closing valve 78 is opened and the piston drive device 76 is driven. This causes the piston 72 to move to the accumulation chamber 70.
Start to extrude the molten resin in a into the injection cylinder 14,
At the same time, the molten resin extruded from the twin-screw extruder 40 also bypasses the accumulation chamber 70a and merges into the injection cylinder 14. Therefore, the screw 16 is rotated at a higher speed than in the case of the first embodiment to start the measuring process.
When the measuring process is completed, the movement of the piston 72 and the rotation of the screw 16 are stopped, and the passage opening / closing valve 7
8 is closed. While the mold closing, injection, holding pressure / cooling and other steps are being performed, the molten resin is stored in the accumulation chamber 70a for the next injection. By this, 〓
It becomes possible to perform the weighing process at a high speed.

In the description of the first embodiment described above,
Although the swivel joint 24 is provided on the melt tube 20, the melt tube 20 may be made of a bendable material and the swivel joint 24 may be omitted. Further, in the description of the first embodiment described above, the gear pump 54 for assisting the extrusion of the molten resin is provided near the extrusion port 40a of the twin-screw extruder 40, but the gear pump 54 is provided at another place, for example, near the vent member 12. It is also possible to provide 54. Also, 2
If the pushing force by the axial extruder 40 is sufficient, the gear pump 54 may not be provided. Further, in the above description of the first embodiment, the twin-screw extruder 40 is stopped after the end of the weighing process, but the twin-screw extruder 40 may be rotated at a very low speed without being stopped. .. By doing so, fluctuations in the molten resin pressure can be reduced and vent up can be prevented. In addition,
In the above description of the first embodiment, the valve 26 is of the manual type, but it may be an automatic pressure regulating valve that opens when the pressure in the vent passage 12a exceeds a set value.
Further, in the description of the second embodiment described above, two injection devices 10a and 10b are provided, but the injection device 10
3 or more are provided, and the passage switching valve 58 is used for the injection device 10.
It is also possible to have a number of switching ports corresponding to the number of. Furthermore, in the description of the third embodiment described above,
Although the accumulator is provided in the device of the first embodiment, the accumulator may be provided in the device of the second embodiment. That is, the vent members 12a and 12b of the two injection devices 10a and 10b arranged in parallel may be provided with accumulating chambers and pistons may be fitted therein. Although the piston drive device 76 is provided in the description of the third embodiment, a fluid pressure cylinder, a linear motor, or the like can be used as the piston drive device 76. Further, in the above description, the injection molding device is a horizontal type, but may be a vertical type. Furthermore, although resin is used as the material in the above description, other materials such as protein, starch, and ceramic may be used.

[0015]

As described above, according to the present invention,
Since the molten material melt-kneaded by the axial extruder can be immediately injection-molded, it is possible to obtain a molded product having a small heat history, no excessive kneading, and excellent physical properties of the material. Moreover, injection molding excellent in energy saving can be performed. Since normal injection molding can be performed without changing the arrangement of machines, it is possible to easily combine machines according to demand and improve work efficiency.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a connection relationship between an injection device and a twin-screw extruder.

FIG. 3 is a diagram illustrating movement of a melt tube when an injection device moves.

FIG. 4 is an enlarged sectional view of part 4 in FIG.

FIG. 5 is a configuration diagram showing a second embodiment of the present invention.

FIG. 6 is a control block diagram.

FIG. 7 is an enlarged sectional view of a vent member according to a third embodiment of the present invention.

FIG. 8 is a configuration diagram showing a conventional molding apparatus.

[Explanation of symbols]

 10 injection device 12 vent member 14 injection cylinder 16 screw 20 melt tube 24 swivel joint 26 valve 28 heater 30 mold clamping device 32 mold 34 mold 40 twin-screw extruder 52 switching valve 54 gear pump (auxiliary pump) 58 passage switching valve 70 Vent member 70a Accumulation chamber 72 Piston 74 Piston rod 76 Piston drive device 78 Passage opening / closing valve

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Naoyuki Murata 1-6-1, Funakoshi Minami, Aki-ku, Hiroshima City, Hiroshima Prefecture Japan Steel Works, Ltd. (72) Inventor Tadada Sakai 1 Funakoshi-minami, Aki-ku, Hiroshima City, Hiroshima Prefecture No. 6-1 Japan Steel Works, Ltd.

Claims (6)

[Claims] 1. A molten material melted and kneaded in a twin-screw extruder and extruded therefrom is supplied to an injection device of an injection molding machine through a bendable pipe, and then the supplied molten material is injected in an injection device. An injection molding method in which measurement is performed, supply of the molten material is stopped at the same time as the measurement is completed, and then the measured molten material is injected into the cavity of a mold that has been clamped. 2. A molten material melted and kneaded in a twin-screw extruder and extruded therefrom is supplied to an accumulator of an injection molding machine through a flexible pipe, and then the molten material is supplied to an injection device from the accumulator. At the same time, the molten material is supplied from the twin-screw extruder to the injection device by bypassing the accumulator, and the supplied molten material is weighed in the injection device. At the same time as the end of the measurement, the supply of the molten material to the injection molding machine is stopped. Then, an injection molding method in which the measured molten material is injected into the cavity of the clamped mold. 3. An injection device (10) and a mold clamping device (30).
In the injection molding apparatus for injecting the molten material measured by the injection cylinder (14) of the injection apparatus into the cavity of the mold (32, 34) installed in the mold clamping apparatus, (40), the vent member (12), the biaxial extruder and the bendable pipe (2 for communicating between the vent member).
0), and the vent member has a vent passage (12a) for communicating between the pipe and the injection cylinder, and a discharge passage (1 for communicating between the injection cylinder and the outside of the injection cylinder).
2b) and an injection molding device respectively formed with. 4. An injection device (10) and a mold clamping device (30).
In the injection molding apparatus for injecting the molten material measured by the injection cylinder (14) of the injection apparatus into the cavity of the mold (32, 34) installed in the mold clamping apparatus, (40), the vent member (70), the biaxial extruder and the bendable pipe (2 for communicating between the vent member).
2), and the vent member communicates with the vent passage (70b) that connects the injection cylinder and the pipe, the accumulation chamber (70a) that communicates with the vent passage, and the injection cylinder and the outside of the injection cylinder. Discharge passage (70
c) and a piston (72) fitted in the accumulating chamber, a piston drive device (76) for driving the piston, and a vent member on the injection cylinder side of the vent member. Passage on-off valve (7
8) and the injection molding apparatus provided with. 5. A plurality of the injection devices are provided,
The injection molding device according to claim 3, wherein a passage switching valve (58) for switching the communication state of the pipes is provided in the pipes that connect the two-screw extruder and the respective injection devices. 6. The injection molding apparatus according to claim 3, 4 or 5, further comprising an auxiliary pump (54) provided between the twin-screw extruder and the pipe for feeding a molten material under pressure.