JPH1134085A - Device and method for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small injection molding device for molding a high grade thin-walled molded product at low cast and also provide a method thereof. SOLUTION: An injection molding device is provided with an injection section 15 for injecting a plasticizing material in the plasticized state and a mold 11 for clamping the plasticizing material injected out of the injection section 15 and molding the same. The mold 11 is constituted of a plurality of counterposed mold constituting bodies 19 and 20 in the horizontal direction across a molding space 29, and a shaping suspending-out section 27 for shaping the plasticizing material injected out of the injection section 15 and suspending the material toward the molding space 29 is provided above the mold constituting bodies 19 and 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding apparatus and a molding method suitable for use in, for example, obtaining a thin molded article.

[0002]

2. Description of the Related Art In general, a film used as an optical material is manufactured by extrusion since continuous molding is possible. However, the film produced by the extrusion molding has a rough surface and cannot be used as an optically high-quality film. As a method for obtaining such a high-quality film, injection molding is known in which a mold having a cavity of a predetermined shape is filled with a molten resin and then cooled and solidified.

In this injection molding, the molten resin filled in the cavity from the gate is cooled and solidified under high pressure, so that the shape of the cavity can be transferred with high precision. Therefore, by previously finishing the cavity surface smoothly, it is possible to obtain a molded product having a smooth surface.

However, in the above-mentioned injection molding, when surface accuracy of a molded product is required, a pin point gate system in which a gate mark remains on the surface or a multi-point gate system in which a weld line is generated cannot be adopted. In the end, we had to adopt a single side gate structure.

In this side gate single point system, for example,
When a 300 mm square film having a thickness of 0.4 mm is formed, the flow distance of the molten resin is increased, and in addition, due to the thinness, the molten resin is solidified before reaching the end of the cavity. Generally, L / T is used as an index indicating the fluidity of a resin.
Although values are used (L: flow length, T: molded product thickness), the limit of the L / T value is set to about 300 even for a PP material having relatively good fluidity, L / T
A value of about 800 is difficult with normal molding.

Further, even if a molten resin is forcibly filled in a cavity using an injection molding apparatus capable of high-speed, high-pressure molding, a molded product having high quality optical characteristics is obtained due to residual stress in the molded product. It is not possible.

As an injection molding apparatus which solves the above-mentioned disadvantages, for example, the one shown in FIG. 6 is provided. In this figure, reference numeral 1 denotes an injection molding device.
The injection molding apparatus 1 includes a plasticizing section 3 for plasticizing the resin pellets in the hopper 2, a measuring / injecting section 4 for measuring and injecting the resin plasticized by the plasticizing section 3, and a measuring / injecting section. A resin supply unit 6 that supplies the injected resin to the cavity of the mold 5 and a mold clamping unit 7 that opens and closes the mold 5 are schematically configured. Is provided.

A movable connecting pipe 8 is provided between the plasticizing section 3 and the metering / injection section 4.
The resin supply section 6 is configured to be movable along the horizontal plane by being mounted on a movable table 9 movable along the horizontal plane.

In the injection molding apparatus 1 having the above configuration,
First, the mold 5 is opened by the mold clamping unit 7. next,
As the movable table 9 moves, the tip of the resin supply unit 6 moves between the molds 5 in the mold open state. At this time, since the movable connecting pipe 8 is disposed between the plasticizing section 3 and the measuring and ejecting section 4, even if the movable table 9 moves, the plasticizing section 3 moves to the measuring and ejecting section 4. It does not hinder the transfer of the resin.

Then, the resin plasticized by the plasticizing section 3 is injected after being measured by the measuring and injection section 4, and is injected into the resin supply section 6.
Is supplied from the nozzle 10 provided at the tip of the mold 5 into the mold 5 in the mold open state. At this time, the moving table 9 is appropriately moved so that the nozzle 10 at the tip of the resin supply unit 6 is located at a predetermined position.

When the supply of the resin is completed, the resin supply section 6 is moved to a position where it does not hinder the mold clamping of the mold 5 by the movement of the movable table 9. Thereafter, the mold 5 is clamped by the mold clamping unit 7 to cool the resin in the cavity. Solidify. According to the injection molding apparatus 1, since no gate is provided, no trace of the gate remains, and the resin supply unit 6 is moved and the mold 5 is moved.
Since the resin is supplied to the mold, a molded product can be obtained without increasing the flow length.

[0012]

However, the above-mentioned conventional injection molding apparatus has the following problems. (1) Since the plasticizing section 3 and the metering / injecting section 4 are provided independently, the apparatus becomes large and expensive. (2) When the flow path from the plasticizing section 3 to the nozzle 10 is long and the injection amount per injection is small, the residence time in the flow path becomes long, and the resin is degraded or thermally decomposed. The likelihood increases. (3) It is necessary to provide the movable base 9 and the movable connecting pipe 8, which makes the apparatus expensive and complicated.

The present invention has been made in consideration of the above points, and provides an injection molding apparatus and a molding method capable of obtaining a small, high-quality thin-walled molded article at a low cost. Aim.

[0014]

In order to achieve the above object, the present invention employs the following constitution. The injection molding apparatus according to claim 1, wherein the injection molding apparatus includes an injection section that injects the plasticizer in a plasticized state, and a mold that tightens and molds the plasticizer injected from the injection section. ,
The mold has a configuration in which a plurality of mold components are horizontally opposed to each other across a molding space, and the plasticizer injected from the injection unit is provided above the mold components. It is characterized in that a shaping protruding portion for shaping and hanging down toward the molding space is provided.

Therefore, according to the injection molding apparatus of the present invention,
The shaped plasticizer is hung from the shaped projection provided above the mold structure toward the molding space between the mold structures. Then, the mold component can be tightened and formed on the sagged plasticizer by approaching in the horizontal direction.

In the injection molding method according to the second aspect, a plurality of mold components are horizontally opposed to each other with a molding space therebetween, and a plasticizer is suspended in the molding space from above the molding space. Later, the mold structure is formed by tightening the plasticizer in the molding space.

Therefore, according to the injection molding method of the present invention,
Even when the plasticizer is supplied to the mold structure, the opening and closing operation of the mold structure is not hindered. Further, after the plasticizer is suspended in the molding space, the plasticizer is tightened, so that it is not necessary to fill the thin space with the plasticizer.

According to a third aspect of the present invention, there is provided an injection molding method.
In the injection molding method described above, after the mold structure is heated to a temperature equal to or higher than the glass transition temperature of the plasticizer and equal to or lower than the thermal decomposition temperature, the plasticizer is tightened and molded. .

Therefore, according to the injection molding method of the present invention,
The moldability and transferability of the plasticizer to the mold structure are improved, and the internal stress of the plasticizer is reduced.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an injection molding apparatus and a molding method according to the present invention will be described below with reference to FIGS. In these figures, the same components as those in FIG. 6 shown as a conventional example are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 2, reference numeral 1 denotes an injection molding device. The injection molding apparatus 1 is schematically composed of a mold 11, a mold clamping unit 12 for opening and closing the mold 11, and an injection unit 15 mounted on a base 13 via an auxiliary stand 14.
The mold clamping part 12 is provided with a fixed plate 16
And a movable plate 18 which is horizontally separated from and approaches the fixed plate 16 by a toggle mechanism 17.

The mold 11 is for molding the plasticizer injected from the injection section 15, and includes a fixed mold 19 (mold structure) fixed to a fixed platen 16 as shown in FIG. , A movable die 20 (a mold component) fixed to the movable plate 18, and the fixed die 19 and the movable die 20 are arranged to face each other in the horizontal direction. In addition, the fixed mold 19 and the movable mold 20 are positioned with respect to each other by a guide pin (not shown), and are kept at a temperature higher than the glass transition temperature of the plasticizer and lower than the thermal decomposition temperature by a temperature controller (not shown). It is cooled after being heated.

The movable die 20 is provided with a receiving pin 21 projecting from the movable die 20 toward the fixed die 19. The receiving pin 21 receives the mold clamping force given by the toggle mechanism 17 in contact with the fixed mold 19 and
9, a molding space 29 for defining the thickness of the molded product is formed between the fixed mold 19 and the movable mold 20.

The injection section 15 plasticizes the plasticizer pellets in the hopper 2 and injects it into the mold 11.
A heating cylinder 23 having a plasticizing space 24 therein; a screw 25 disposed in the plasticizing space 24 so as to be rotatable around an axis and movable in an axial direction; And a heating cylinder cover 26 provided.

The screw 25 plasticizes while feeding the plasticizer pellets forward by rotating, and moves the plasticized material in the plasticized state forward in the axial direction and injects it. The heating cylinder cover 26 is connected and fixed to the heating cylinder 23, and a communication hole 28 communicating with the plasticizing space 24 is formed inside the heating cylinder cover 26. A die 27 (shape protruding portion) is fixed to the tip of the heating cylinder cover 26 in the injection direction.

The die 27 is for shaping the plasticizer injected through the communication hole 28, is provided above the mold 11, and has a shaping space 30 therein. The shaping space 30 has an L-shaped cross section in the emission direction.
One end is a communication portion 31 that communicates with the communication hole 28, and the other end is provided on the lower surface 33 and is an opening 32 that opens toward a molding space 29 formed between the fixed die 19 and the movable die 20. Things.

Further, as shown in FIG.
The opening width L of the cross-sectional shape in the direction orthogonal to the injection direction gradually increases obliquely downward starting from the communication portion 31 at the opening portion 32. For example, when it is set to 350 mm, for example, 400 m
m. On the other hand, as shown in FIG. 1, when the opening width T of the opening 32 in the injection direction is set to, for example, 0.4 mm, the opening width K of the molding space 29 is set to 0.4 mm. For example, it is set to 0.6 mm so as to be larger than T by a predetermined amount.

The operation of the injection molding apparatus and the molding method having the above configuration will be described below. First, the plasticized resin in the plasticized state is injected in the previous cycle, and the screw 25 positioned at the forefront in the injection direction moves rearward in the injection direction while rotating around the axis. As a result, the plasticizer pellets in the hopper 2 are supplied into the plasticizing space 24 and sent out forward in the plasticizing space 24. At this time, the plasticizing material is melted by the heating of the heating cylinder 23 and the shearing heat of the plasticizing material pellets to be in a plasticized state.

When the plasticization of the predetermined amount is completed, the screw 25 is completely retracted and rotated, and the measuring process is completed. At this time, the screw 25 sucks back to prevent resin leakage from the die 27. Further, the movable plate 18 moves in the horizontal direction with respect to the fixed plate 16 and is separated from the fixed plate 16 by the mold opening action of the toggle mechanism 17.

A fixed mold 19 is fixed to the fixed board 16, and a movable mold 20 is fixed to the movable board 18.
Due to the horizontal movement of the movable platen 18, the movable mold 20 is also moved horizontally away from the fixed mold 19.

Then, when shifting to the injection step, the screw 25 moves at a constant speed in the injection direction. As a result, the plasticized material in the plasticized state in the plasticized space 24 passes through the communication hole 28 and then reaches the shaping space 30 of the die 27 from the communication portion 31.

The opening 32 at the other end of the shaping space 30 has an opening width K in the injection direction of 0.6 mm and an opening width L in a direction perpendicular to the opening direction K of 400 mm. Lower surface 3 of dice 27 arranged above mold 11
3 and open to a molding space 29 formed between the fixed mold 19 and the movable mold 20.

Therefore, the plasticizing material that has reached the shaping space 30 is shaped into a sheet having a width of 0.6 mm and a length of 400 mm as the screw 25 is injected, and hangs down from the opening 32 toward the gap 29. Can be lowered. The hanging plasticizer reaches the molding space 29 by gravity, and the injection process is completed. After the completion of the mold clamping, the screw 25 shifts to the measuring step again for injection in the next cycle.

When the suspended plasticizer reaches the molding space 29, the movable mold 20 approaches the fixed mold 19 in the horizontal direction via the movable plate 18 by the mold clamping action of the toggle mechanism 17. . Then, the receiving pin 21 provided on the movable mold 20 comes into contact with the fixed mold 19 to receive the mold clamping force given by the toggle mechanism 17, and the fixed mold 19 and the movable mold 2
The gap 29 between 0 and 0 is defined so that the opening width T is 0.4 mm. As a result, the plasticizing material having a width of 0.6 mm and having a width of 0.
It is tightened as shown in FIG. 5 so as to be 4 mm, that is, a molded product having a thickness of 0.4 mm.

At this time, the temperature of the fixed mold 19 and the movable mold 20 has been raised in advance by the temperature control device to a temperature equal to or higher than the glass transition temperature of the plasticizer and equal to or lower than the thermal decomposition temperature. The mold is formed with its internal stress relaxed. Then, the plasticizer is molded for a predetermined time in the tightened state. That is, when the mold clamping is completed, the fixed mold 19 and the movable mold 20 are cooled by the control of the temperature control device, and take the heat from the plasticizer to cool and solidify the plasticizer for a predetermined time.

Thereafter, the movable mold 20 moves in the direction away from the fixed mold 19 via the movable plate 18 by the mold opening action of the toggle mechanism 17. Then, the sheet-shaped plasticizer molded to a thickness of 0.4 mm is taken out of the mold 11 and molding is completed.

According to the injection molding apparatus and the molding method of the present embodiment, in addition to being able to plasticize, measure and inject the plasticizer in the injection section 15, Injection is also performed by suspending the plasticizer from above the mold 11 into the molding space 29.
It is not necessary to move the injection unit 15 including the die 27 so as not to hinder the opening and closing of the unit 1.
Inexpensive structure is enough.

Further, after shaping by the die 27, in addition to forming by tightening with the mold 11, the mold 11 is heated in advance to a temperature higher than the glass transition temperature of the plasticizer and lower than the thermal decomposition temperature. Since there is no molding failure such as unfilled or warped, it is easy to produce high-quality thin molded products with excellent transferability, for example, molded products with small birefringence and excellent optical characteristics if films. it can.

In the above embodiment, the die 2
7 is provided at the leading end of the emitting section 15 in the emitting direction.
The present invention is not limited to this. For example, a configuration may be used in which the die 27 is fixed to the upper surface of the fixed mold 19 and the nozzle of the injection unit 15 makes nozzle contact with the die 27. Also,
Although the receiving pin 21 is used as a means for defining the thickness of the molded product, the present invention is not limited to this. For example, the position of the movable plate 18 can be controlled with high accuracy by using a servomotor for the toggle mechanism 17. The configuration may be as follows.

On the other hand, the width of the plasticizer hanging from the opening 32 of the die 27 is determined by the opening width K of the opening 32. May be changed, or the injection speed at the time of injection by the screw 25 may be adjusted.

[0041]

As described above, according to the injection molding apparatus of the first aspect, a plurality of mold components are horizontally arranged opposite to each other across the molding space, and the mold components are disposed above the mold components. The plasticizing material in a plasticized state is formed, and a shaping and protruding portion for hanging down toward the gap is provided.

Thus, since the injection into the mold is performed by hanging the plasticizer from above, there is no need to move the injection section or the shaping and hanging section so as not to hinder the opening and closing of the mold. This is an excellent effect that a small-sized and simple structure is required, that is, an inexpensive injection molding apparatus can be obtained.

According to the molding method according to the second aspect, the plurality of mold components are horizontally arranged opposite to each other across the molding space, and the plastic component in the plasticized state is formed from above. After hanging down toward the molding space, the plasticizer is tightened and molded. This makes it easy
In addition, there is an excellent effect that a high-quality thin molded product can be obtained at low cost.

According to the molding method of the third aspect, after the mold component is heated to a temperature equal to or higher than the glass transition temperature of the plasticizer and equal to or lower than the thermal decomposition temperature, the plasticizer is tightened and formed. Has become. Thereby, for example, in the case of a film, there is an excellent effect that a high-quality thin-walled molded product having a small birefringence and excellent optical characteristics can be easily produced.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of the present invention, and is a cross-sectional view in which a die provided at a tip of an injection unit is disposed above a mold.

FIG. 2 is a view showing the embodiment of the present invention, and is a front view in which a plasticizer is hung in a molding space between a fixed die and a movable die.

FIG. 3 shows a die A of the injection molding apparatus of the present invention.
FIG.

FIG. 4 is a front view of a mold constituting the injection molding apparatus of the present invention.

FIG. 5 is a view showing the embodiment of the present invention, and is a front view in which a hanging plasticizer is fastened to a fixed mold and a movable mold.

FIG. 6 is a front sectional view showing an example of a conventional injection molding apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injection molding apparatus 11 Die 15 Injection part 19 Fixed die (die structure) 20 Movable die (die structure) 27 Dice (shaping protruding part) 29 Molding space

Claims (3)

[Claims] 1. An injection molding apparatus comprising: an injection section for injecting a plasticized material in a plasticized state; and a mold for tightening and molding the plasticized material injected from the injection section, wherein the mold is A plurality of mold components are horizontally arranged to face each other with a molding space interposed therebetween. Above the mold components, the plasticizer injected from the injection section is shaped and the An injection molding apparatus comprising a shaping and hanging portion for hanging toward a molding space. 2. A plurality of mold components are horizontally opposed to each other across a molding space, and after a plasticizing material is suspended in the molding space from above the molding space, the mold components are An injection molding method, wherein the plasticizing material is tightened and molded in the molding space. 3. The injection molding method according to claim 2, wherein the plasticizer is tightened after the temperature of the mold component is raised to a temperature equal to or higher than a glass transition temperature of the plasticizer and lower than a thermal decomposition temperature. An injection molding method characterized by forming by injection molding.