JP3027619B2 - Injection molding method and apparatus - Google Patents

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 In order to obtain a molded product of a polymer alloy or a composite resin, a resin material is sufficiently melted and kneaded in advance by an extruder at a resin maker to obtain a uniform compounding ratio.
Pellets granulated by a granulator were used. This is because the screw of the injection device is uniaxial and the ratio of the screw diameter to the screw length (usually "L
/ D ”) is designed to be small, and in the case of the resin material as described above, it cannot be sufficiently kneaded. The pellets are supplied into the injection cylinder from the raw material supply port of the injection device, kneaded and melted by the rotation of the screw and heating by the heater to form a molten resin, and are measured by the rotation of the screw. Next, by stopping the rotation of the screw and moving the screw in the injection direction, a predetermined amount of molten resin is injected into the mold cavity from the nozzle of the cylinder. Thereby, a molded article can be injection-molded.

[0003]

However, the conventional injection molding method using pellets as described above has a problem that the cost of the raw material resin is increased by the time required for forming pellets. In addition, since the raw material resin is heated twice during granulation and during molding, the heat history increases,
There is a disadvantage that thermal degradation occurs. An object of the present invention is to solve such a problem.

[0004]

According to the present invention, a molten resin extruded from an extruder is directly introduced into an injection device of an injection molding machine, and the molten resin is measured in the injection device. The above problem is solved by injecting into a mold. That is, the injection molding method of the present invention provides an extruder (22)
Melt-kneaded molten resin is extruded from the extruder (22) at the inner, through the second on-off valve of the intermediate unit (20, 44) (30), the injection device through the nozzle of the injection device (24) ( When the injection screw (38) of the injection device (24) is retracted and a predetermined amount of supplied resin accumulates in the cylinder ( 36 ) of the injection device (24), the second on-off valve (30) is closed, and the intermediate units (20, 44) are closed. ) The first on-off valve (28) opens,
The measured molten resin in the cylinder ( 36 ) of the injection device (24) is injected into the mold cavity (C), and after injection and filling,
The first on-off valve (28) is closed and the intermediate unit (20, 4) is closed.
The pressure is held by a pressure holding cylinder (26) connected to 4). An apparatus for performing the above method includes a mold apparatus (40), an intermediate unit (20),
An extruder (22), an injection device (24), and a pressure holding cylinder (26) are provided.
Fixed board (10) and fixed board (10) arranged opposite to this
A movable platen (12) movable in a direction approaching or away from the movable platen, a fixed-side mold (14) fixed to a fixed platen (10), and a movable-side mold fixed to the movable platen (12) ( 16), and the cavities (C) are formed by the two dies (14 and 16). The intermediate unit (20) has a die device connection part (20a) and an extruder A connection part (20b), an injection device connection part (20c),
A pressure holding cylinder connecting portion (20d) and a first passage (20e)
, A second passage (20f), and a third passage (20g) are formed, and the mold device (40) is connected to the mold device connecting portion (20a), and the extruder is connected. Department (20
The extruder (22) is connected to b), the injection device (24) is connected to the injection device connection portion (20c), and the pressure holding device is connected to the pressure holding cylinder connection portion (20d). The cylinder (26) is connected to the first passage (20).
e) connects between the mold device connection part (20a) and the injection device connection part (20c), and the second passage (20f)
The first passage (20e) and the extruder connection part (20b) are connected, and the third passage (20g) is connected to the first passage (20).
e) and the pressure-holding cylinder connecting portion (20d), and the intermediate unit (20) connects the first passage (20e) upstream of the third passage (20g) connecting portion and the second passage (2).
0f) The first extruder (22) includes a first on-off valve (28) that opens and closes between downstream sides of the connection portion, and a second on-off valve (30) that opens and closes the second passage (20f). )
It has a cylinder (32) and a screw (34) rotatably fitted thereto, and is capable of melting and kneading a resin raw material and extruding it as a molten resin into the intermediate unit (20). , The injection device (24)
It has an injection cylinder (36) and an injection screw (38) movably fitted thereto, and measures the molten resin supplied from the extruder (22),
The measured molten resin can be injected into the cavity (C) of the mold device (40), and the pressure-holding cylinder (26) is provided with a pressure-holding piston (42) movably fitted thereto. Holding pressure piston (42)
It is possible to push the molten resin in the first passage (20e) toward the cavity (C). In addition, the code | symbol in a parenthesis shows the corresponding member of an Example.

[0005]

When the molten resin sufficiently melted and kneaded in the extruder is extruded from the extruder, it is immediately supplied to the injection device of the injection molding machine. By retreating the injection screw of the injection device, the molten resin is measured, and a predetermined amount of the molten resin is stored in the injection cylinder. When a predetermined amount of the molten resin is stored, the supply of the molten resin is stopped. Next, the injection screw is moved in the injection direction. That is, a predetermined amount of molten resin is injected into the mold. Thereby, even if it is resin raw materials, such as a polymer alloy and a composite resin, an inexpensive molded product with little heat history can be injection-molded.

[0006]

FIG. 1 shows a first embodiment of the present invention. Fixed board 1
The mold apparatus 40 is constituted by the movable plate 12, the movable mold 12, the fixed mold 14, the movable mold 16, the tie bar 18, and the like. A cavity C is formed by the two dies 14 and 16. A sprue portion 14 a communicating with the cavity C is formed in the fixed mold 14. The intermediate unit 20 is arranged on the fixed platen side of the fixed mold 14. The intermediate unit 20 includes a mold device connecting portion 20a capable of contacting the sprue portion 14a of the fixed mold 14, an extruder connecting portion 20b to which a twin screw extruder 22 described later is connected, and a nozzle of an injection cylinder 36 described later. The injection device connecting portion 20c to which the contact 36a can be contacted, the pressure-holding cylinder connecting portion 20d to which the pressure-holding cylinder 26 to be described later is connected, and the first passage 2 for connecting each connecting portion
0e, a second passage 20f, and a third passage 20g. The first passage 20e is provided with a first opening / closing valve 28 upstream of a position connected to the third passage 20g and downstream of a position connected to the second passage 20f. A second on-off valve 30 is provided in the second passage 20f. The two on-off valves 28 and 30 are connected to the first passage 20e and the second passage 20e.
The passage 20f can be opened and closed. The twin-screw extruder 22 is connected to the extruder connection part 20b of the intermediate unit 20.
A biaxial screw 34 that can rotate with each other is fitted in a biaxial cylinder 32 of the biaxial extruder 22. The twin screw extruder 22 can extrude the molten resin into the second passage 20f. Injection device connection part 20 of intermediate unit 20
The injection device 24 is connected to c. Injection device 24
In the drawing, the left end of the injection cylinder 36 has a nozzle 36a.
Are formed. An injection screw 38 is movably fitted in the injection cylinder 36. A resin reservoir 36b is formed by the inner diameter of the injection cylinder 36 and the tip of the injection screw 38. The molten resin extruded from the twin-screw extruder 22 passes through the second passage 20f and the first passage 20e, and is stored in the resin storage portion 36b of the injection cylinder 36.
Extruded. Thereby, the injection screw 38
The weighing operation can be performed by moving from the injection end position on the left side of the illustrated position to the weighing completed position illustrated.
Further, the injection screw 38 moves to the left from the illustrated position to inject the molten resin stored in the resin storage portion 36b into the cavity C through the first passage 20e and the first opening / closing valve 28. It is possible. A pressure holding cylinder 26 is provided at a downstream position closest to the mold device connecting portion 20a. A pressure holding piston 42 is fitted to the pressure holding cylinder 26. The holding pressure piston 42 is connected to the third passage 20.
The pressure holding operation can be performed by pushing the molten resin in g toward the first passage 20e.

Next, the operation of the first embodiment will be described.
The movable platen 12 and the movable side mold 16 of the mold apparatus 40 are located at the mold open position on the left side of the position shown in the drawing.
The injection screw 38 in 6 is at the injection end position on the left side of the position shown. At this time, the first on-off valve 28 is in the closed position, and the second on-off valve 30 is switched from the closed position to the open position. The molten resin extruded from the twin screw extruder 22 is
It is stored in the resin storage part 36b through the second passage 20f, the second on-off valve 30, and the first passage 20e. That is, the weighing process is started. As a result, the injection screw 38 is gradually pushed rightward in the figure to reach the metering completion position shown in the figure. The second on-off valve 30 is switched to the closed position by the signal of the completion of the measurement. When the movable platen 12 moves from the mold open position on the left side of the illustrated position to the illustrated mold closed position at a predetermined timing, an injection signal is output. The first on-off valve 28 is switched to the open position, and the injection screw 38 moves to the left in the drawing, so that the molten resin flows through the first passage 20e and the first on-off valve 28.
And is injected into the cavity C through the sprue portion 14a. After the injection is completed, the first opening / closing valve 28 is switched to the closed position, and the pressure-holding piston 42 presses the molten resin in the third passage 30g to apply pressure to the resin in the cavity C. That is, a pressure holding step is performed. During this time, the weighing process is started again. On the other hand, when the predetermined pressure-holding / cooling time has elapsed, the force for pressing the pressure-holding piston 42 is released, the mold is opened, and the molded product is removed from the cavity. As described above, the molded article can be repeatedly molded.

FIG. 2 shows a second embodiment of the present invention. The difference of the second embodiment from the first embodiment is that two sets of mold devices 40 are provided, and the intermediate unit 44 is configured to connect the two sets of mold devices 40. The pressure holding cylinder 26, the pressure holding piston 42, the injection device 24, the first on-off valve 28, and the second on-off valve 3
0 is arranged one by one. The second passage 44f has a branch portion 44f _1, which is from one of the twin screw extruder 22 can be supplied to the molten resin in the resin reservoir 36b of each of the injection apparatus 24.
The twin-screw extruder 22 is selected to have an extrusion capacity capable of supplying a molten resin to two injection devices 24 during a predetermined cycle time. The operation of the second embodiment is performed in the same manner as the operation of the first embodiment, but it is preferable that one molding cycle is shifted by half from the other molding cycle. Thereby, the molten resin continuously extruded from the extruder can be switched and supplied with good timing.
Other operations are the same as those of the first embodiment, and thus the details are omitted. In the above description, the molten resin is supplied from the extruder 22 to the injection device 24. However, when using a resin material other than the polymer alloy and the composite resin, by removing the extruder 22 together with the intermediate unit 20, It can be used as a normal injection molding machine. In the above description, one twin-screw extruder 22 supplies molten resin to up to two injection devices 24. However, the molten resin may be supplied to three or more injection devices 24. No problem. In the above description, a twin-screw extruder is used as the extruder 22, but a single-screw extruder may be used as long as it has a large L / D.

[0009]

As described above, according to the present invention, molding can be carried out while preventing thermal deterioration of a polymer alloy or a composite resin. Moreover, even if it is a polymer alloy or a composite resin, it is not necessary to use the pelletized raw resin, so that these molded products can be made inexpensive.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of an injection molding apparatus according to a first embodiment.

FIG. 2 is a partial sectional view of an injection molding apparatus according to a second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Fixed board 12 Movable board 14 Fixed side mold 16 Movable side mold 20 Intermediate unit 20a Mold device connection part 20b Extruder connection part 20c Injection device connection part 20d Pressure holding cylinder connection part 20e First passage 20f Second passage 20g Third passage 22 Extruder 24 Injection device 26 Pressure holding cylinder 28 First on-off valve 30 Second on-off valve 32 Cylinder 34 Screw 36 Injection cylinder 38 Injection screw 40 Mold device 42 Holding piston 44 Intermediate unit 44a Mold device connection portion 44b Extruder connection 44c Injection device connection 44d Holding cylinder connection 44e First passage 44f Second passage 44f ₁ branch 44g Third passage C Cavity

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-53-59758 (JP, A) JP-A-60-162620 (JP, A) JP-A-3-178417 (JP, A) JP-A 63-59 11318 (JP, A) JP-A-2-295715 (JP, A) JP-A-2-281919 (JP, A) JP-A-48-32667 (JP, U) JP-B-36-11233 (JP, B1) (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 45/00-45/84

Claims (3)

(57) [Claims] 1. A extruded from the extruder (22) in a melt-kneaded molten resin extruder (22) through the second on-off valve of the intermediate unit (20, 44) (30), an injection device The injection screw (38) of the injection device (24) is retracted via the nozzle of (24), and when a predetermined amount of supplied resin accumulates in the cylinder ( 36 ) of the injection device (24), the second on-off valve (30) ) Is closed, the first on-off valve (28) of the intermediate unit (20, 44) is opened, and the measured molten resin in the cylinder ( 36 ) of the injection device (24) is injected into the mold cavity (C). An injection molding method in which after the injection filling, the first on-off valve (28) is closed and the pressure is held by the pressure holding cylinder (26) connected to the intermediate unit (20, 44). 2. A mold device (40) and an intermediate unit (2).
0), an extruder (22), an injection device (24), and a pressure holding cylinder (26).
0) is a fixed plate (10), a movable plate (12) which is arranged opposite to the fixed plate (10) and is movable in a direction approaching or away from the fixed plate (10), and a fixed side fixed to the fixed plate (10). It has a mold (14) and a movable mold (16) fixed to the movable plate (12).
A cavity (C) is formed by 6), and the intermediate unit (20) is connected to the mold device connecting portion (20a).
Extruder connection (20b) and injection device connection (20
c), the pressure holding cylinder connecting portion (20d), the first passage (20e), the second passage (20f), and the third passage (20d).
g), and a mold device connection part (20a).
Is connected to the mold device (40), the extruder connection portion (20b) is connected to the extruder (22), and the injection device connection portion (20c) is connected to the injection device (2).
4) is connected, and the holding cylinder connecting portion (20d)
Is connected to the pressure holding cylinder (26).
The passage (20e) connects between the mold device connecting portion (20a) and the injection device connecting portion (20c), and the second passage (2)
0f) is the first passage (20e) and the extruder connection (20
b), the third passage (20g) connects the first passage (20e) and the pressure-holding cylinder connection portion (20d), and the intermediate unit (20) connects the first passage (20g). 20
e) the upstream side of the third passage (20g) connection portion and the second
The extruder has a first on-off valve (28) that opens and closes between downstream of the passage (20f) connection portion, and a second on-off valve (30) that opens and closes the second passage (20f). (2
2) has a cylinder (32) and a screw (34) rotatably fitted to the cylinder (32), and is capable of melting and kneading a resin material and extruding it as a molten resin. The device (24) comprises an injection cylinder (3
6) and an injection screw (38) that is movably fitted to the mold device, and that measures the molten resin supplied from the extruder (22), and transfers the measured molten resin to the mold device. (40), and the pressure holding cylinder (26) has a pressure holding piston (42) movably fitted to the pressure holding cylinder (26). 42) is the first passage (20)
e) An injection molding apparatus capable of pushing the molten resin in the cavity toward the cavity (C). 3. A plurality of mold units (40), an intermediate unit (44), an extruder (22), as many injection units (24) as the mold units (40), and a mold unit (40). ), And the number of holding cylinders (26) is equal to the number of the pressure holding cylinders (26). A movable plate (12) movable in the direction, a fixed mold (14) fixed to the fixed plate (10), and a movable mold (16) fixed to the movable plate (12). And both dies (14
・ Cavity (C) is formed by (16),
The intermediate unit (44) includes a plurality of mold device connection portions (44a), an extruder connection portion (44b), and the same number of injection device connection portions (44c) as the mold device connection portions (44a).
The same number of pressure-holding cylinder connections (44d) as the number of mold device connections (44a), and the same number of first pressure-type cylinder connections (44a) as mold device connections (44a).
A passage (44e), a second passage (44f) having the same number of branches (44f ₁ ) as the mold device connection (44a), and a third passage (44g) as many as the mold device connection (44a).
Are formed, the mold device (40) is connected to each mold device connecting portion (44a), and the extruder (22) is connected to the extruder connecting portion (44b). The injection device (2c) is connected to each injection device connection portion (44c).
4) are connected, and each pressure holding cylinder connection portion (44
The holding cylinder (26) is connected to d),
Each first passage (44e) connects between the mold device connecting portion (44a) and the injection device connecting portion (44c), and each second passage (44e)
The passage (44f) connects the first passage (44e) and the extruder connection portion (44b) through a branch portion (44f ₁ ), and each third passage (44g) is connected to the first passage (44e). ) And the pressure holding cylinder connection portion (44d), and the intermediate unit (44) connects the first passages (44e) upstream of the third passage (44g) connection portion and the second passages (44d).
branch of f) (44f ₁₎ first on-off valve for opening and closing between the downstream side of the connecting portion (28), each second passage (44
f) a second on-off valve (30) that opens and closes f).
The extruder (22) has a cylinder (32) and a screw (34) rotatably fitted to the cylinder (32). The extruder (22) can melt and knead the resin material and extrude it as a molten resin. The injection device (24) includes an injection cylinder (36) and an injection screw (38) movably fitted to the injection cylinder (36).
The molten resin supplied from 2) can be measured, and the measured molten resin can be injected into the cavity (C) of the mold device (40), and the pressure holding cylinder (26) A holding piston (42) movably fitted therein, the holding piston (42) comprising:
An injection molding device capable of pushing the molten resin in the first passage (44e) toward the cavity (C).