KR101402698B1 - Viscous fluid-assisted injection molding apparatus and molding controlling method the same - Google Patents

Abstract

The present invention relates to an injection molding apparatus for a viscous fluid and a controlling method thereof. The disclosed injection molding apparatus for a viscous fluid comprises: a supply unit which supplies a viscous fluid stored by being connected to a first duct; a second duct which is connected to the first duct and reinstates the viscous fluid to the supply unit; a measurement unit which is installed in the second duct and performs filling with a predetermined amount of the viscous fluid used in a mold by measuring the viscous fluid supplied from a supply pump; a high pressure gas unit which transfers the viscous fluid filled in the measurement unit to the mold by passing through a fourth duct by supplying high pressure to the measurement unit through the third duct connected to the second duct; a fluid path control unit which controls linkage between the measurement unit and the supply unit and between the measurement unit and the mold by being installed in the second duct and the fourth duct; a direction control valve which is connected to the fourth duct and injects the viscous fluid into an inner space of the mold or discharges the viscous fluid to a fifth duct by performing switching after completing injection by being installed at an entrance part of the mold; and a control unit which controls the supply pump, the high pressure gas unit, the fluid path control unit and the direction control valve.

Description

TECHNICAL FIELD [0001] The present invention relates to a viscous fluid injection molding apparatus and a control method thereof,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a viscous fluid injection molding apparatus and a control method thereof, and more particularly, to a viscous fluid injection molding apparatus and a control method thereof, To a viscous fluid injection molding apparatus capable of increasing productivity and reducing environmental pollution, and a control method thereof.

Injection molding is widely used in plastic molding technology, and injection molding technology is being developed in various ways as plastic products are diversified and advanced. The problem that these various injection molding technologies have in common is closely related to the characteristics of the raw material called plastic resin.

Plastic resin has a low heat transfer coefficient, which is disadvantageous to heat conduction, and it takes a long time to cool and solidify. In addition, since the volume shrinkage is accompanied by the cooling of the plastic resin, it is difficult to obtain a molded article exactly the same as the cavity of the injection mold.

In order to solve this problem, water-assisted injection molding technology, which uses incompressible water instead of compressible gas, has been developed to produce an inner hollow shape by hollow plastic parts manufacturing technique of the hosiery, and is applied to various products.

Since water has a higher viscosity than gas, when the water is injected into the mold, a solidified and highly viscous film is formed on the contact surface of the water with the molten plastic, thereby cooling the molten resin while pushing the molten resin toward the front side .

As a background of the present invention, Korean Patent Laid-Open Publication No. 2010-0050396 (entitled "Molding Apparatus and Molding Method of Hollow Article") is proposed.

Conventional molding apparatuses are used for spraying water and gas to a plastic injection mold to form a hollow portion. In this case, the internal surface is not smoothly processed due to fingering due to the phenomenon of fingering in the bending of the injection mold due to the injected gas .

In addition, since the conventional injected water and gas are injected in a state in which they can not be metered in advance, there is a problem that the injection pressure can not be maintained constant.

Further, since the injected gas and water can not be recycled, there is a problem in that it is not environmentally friendly.

Therefore, there is a need to improve this.

The present invention has been made in view of the above-mentioned need, and it is an object of the present invention to provide a hollow part of a plastic part by injecting a viscous fluid into a mold by using a high pressure gas after measuring a set amount of viscous fluid, And an object thereof is to provide a viscous fluid injection molding apparatus and a control method thereof.

The present invention uses a viscous fluid containing water or a highly viscous fluid having a cooling capacity of 4 times and a thermal conductivity of 40 times or more as compared with a gas, so that a viscosity of 30% to 40% An object of the present invention is to provide a fluid injection molding apparatus and a control method thereof.

An object of the present invention is to provide a viscous fluid injection molding apparatus and a control method thereof capable of reducing fingering phenomena frequently occurring in gas injection molding and enabling an inner surface of an injection molding to be made beautiful .

According to an aspect of the present invention, there is provided a viscous fluid injection molding apparatus including: a supply unit connected to a first conduit to supply a stored viscous fluid; A second conduit connected to the first conduit and returning the viscous fluid to the supply section; A metering unit installed in the second conduit for metering and filling the viscous fluid supplied from the supply pump by a predetermined amount used in the mold; A high pressure gas unit which supplies high-pressure gas to the metering unit through a third conduit connected to the second conduit, and transfers the viscous fluid filled in the metering unit to the mold via the fourth conduit; A flow control unit installed in the second conduit and the fourth conduit for controlling the connection between the metering unit and the supply unit, the metering unit and the mold; A direction control valve connected to the fourth conduit and provided at an inlet of the mold to inject viscous fluid into the injection mold of the mold or to switch after completion of injection and discharge the viscous fluid into the fifth conduit; And a control unit for controlling the supply pump, the high-pressure gas unit, the flow path control unit, and the direction control valve.

The supply section may further comprise: a chamber for storing viscous fluid; And a supply pump provided at an outlet side of the chamber for supplying a viscous fluid of a predetermined amount to the metering section.

The first channel may include a first check valve to prevent the viscous fluid supplied from the supply unit to the metering unit from flowing backward.

Further, the metering section is a cylinder for supplying metered, stored viscous fluid by operating the piston with the gas of the cylinder or the high-pressure gas unit.

The third pipe is provided with a second check valve for preventing the viscous fluid returning from the metering unit to the supply unit through the second channel to flow back to the high-pressure gas unit.

The control unit may determine the completion time of the injection molding of the mold through the supply end of the injector supplying the synthetic resin to the mold before operating the high-pressure gas unit.

The fourth pipe may be provided with a pressure sensor unit for measuring a viscous fluid pressure measurement value supplied from the metering unit through the high-pressure gas unit through the control unit, and the control unit may measure The pressure of the supply gas of the high-pressure gas unit is adjusted to adjust the viscous fluid supply pressure of the metering unit when the measured viscous fluid pressure measurement value is out of the range of the viscous fluid pressure reference value to be injected into the mold.

The flow control unit includes a first opening / closing valve that is provided in the second conduit and opens when the viscous fluid returns from the metering unit to the supply unit, and is shut off when the gas is supplied from the high pressure gas unit; And a second open / close valve installed in the third conduit, the second open / close valve intercepted when the viscous fluid returns from the metering section to the supply section, and opened when the gas is supplied from the high pressure gas unit.

And a purge portion for forcibly discharging the viscous fluid remaining in at least one of the inside of the directional control valve and the inside of the mold by the control of the control portion and returning the fluid to the supply portion.

The purging unit may include a connection pipe connected to an inlet of the mold; A working valve installed in the connection pipe for opening and closing the connection pipe; An air supply unit provided at an entrance side of the connection pipe to discharge the viscous fluid remaining in the mold or the direction control valve; And a sixth conduit having one end in the mold and the other end connected to the fifth conduit.

The control method of a viscous fluid injection molding apparatus according to the present invention comprises the steps of: opening a first on-off valve installed in a second pipe through a control of a control unit and blocking a second on-off valve installed on a fourth pipe; The control unit activates the supply pump of the supply unit to meter the viscous fluid stored in the chamber to the metering unit through the first channel and the second channel, Closing the first opening / closing valve, opening the second opening / closing valve, and regulating opening of a direction adjusting valve installed at an inlet of the mold; The control unit operates the high-pressure gas unit and injects the high-pressure gas into the mold through the third pipe, the second pipe, the metering unit, the fourth pipe, and the direction control valve to form a hollow portion .

In addition, the control unit determines the completion time of the injection molding of the mold through the supply end of the injection machine that supplies the synthetic resin to the mold before operating the high-pressure gas unit.

Also. Wherein the control unit controls the viscous fluid pressure measured by the fourth pipe through the control of the pressure sensor provided in the fourth conduit to exceed the viscous fluid pressure reference value to be injected into the mold, And adjusting the supply gas pressure of the high-pressure gas unit to adjust the pressure of the high-pressure gas unit.

After the completion of injection of the mold, the controller operates the purging unit to recover the viscous fluid remaining in the cavity of the injection mold of the mold and the directional control valve through the fifth and sixth conduits to the chamber Further comprising the steps of:

The viscous fluid injection molding apparatus and the control method thereof according to the present invention increase the productivity by increasing the productivity by measuring the set amount of the viscous fluid and forming the hollow part of the plastic part by injecting the viscous fluid into the mold at a high pressure using the high pressure gas, .

The present invention uses a viscous fluid containing water or a highly viscous fluid having a cooling capacity of 4 times and a thermal conductivity of 40 times or more as compared with the gas, so that the productivity can be improved by 30% to 40%.

INDUSTRIAL APPLICABILITY The present invention can reduce the fingering phenomenon frequently occurring in gas injection molding and can make the inner surface of the injection molded article beautiful.

1 is a configuration diagram of a viscous fluid injection molding apparatus according to an embodiment of the present invention,
2 is a view showing a viscous fluid metering process of the viscous fluid injection molding apparatus according to an embodiment of the present invention,
3 is a view showing a viscous fluid injection process of the viscous fluid injection molding apparatus according to an embodiment of the present invention,
4 is a view showing a purging process of a viscous fluid injection molding apparatus according to an embodiment of the present invention,
5 is an overall flowchart of a viscous fluid injection molding apparatus according to an embodiment of the present invention.

Hereinafter, a viscous fluid injection molding apparatus and a control method thereof according to an embodiment of the present invention will be described with reference to the accompanying drawings.

In this process, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms described below are defined in consideration of the functions of the present invention, which may vary depending on the intention or custom of the user, the operator. Therefore, definitions of these terms should be made based on the contents throughout this specification.

2 is a view showing a viscous fluid metering process of a viscous fluid injection molding apparatus according to an embodiment of the present invention, and FIG. 3 is a view showing a viscous fluid injection molding apparatus according to an embodiment of the present invention. FIG. 4 is a view showing a purging process of a viscous fluid injection molding apparatus according to an embodiment of the present invention. FIG. 4 is a view showing a process of injecting a viscous fluid in a viscous fluid injection molding apparatus according to an embodiment of the present invention.

1 to 4, a viscous fluid injection molding apparatus according to an embodiment of the present invention includes a supply unit 10, a second conduit 20, a metering unit 30, a high-pressure gas unit 40, A control unit 50, a direction control valve 60, and a control unit 80.

The supply section 10 is connected to the first conduit 12 to supply the stored viscous fluid.

A viscous fluid is a fluid including water or highly viscous oil.

The viscous fluid can be any fluid that can reduce the existing fingering phenomenon.

The supply section 10 includes a chamber 14 for storing viscous fluid and a supply pump 16 provided at the outlet side of the chamber 14 and for supplying a predetermined amount of viscous fluid to the metering section 30 .

The chamber 14 is preferably a viscous fluid reservoir capable of storing a viscous fluid and has a capacity such that it can be used more than once.

Here, the supply unit 10 may be a configuration capable of continuously supplying water as a substitute for the chamber 14.

The first channel 12 is provided with a first check valve 22 for preventing the viscous fluid supplied from the supply unit 10 to the metering unit 30 from flowing backward.

The first check valve 22 is installed between the merging point of the first conduit 12 and the second conduit 20 and the feed pump 16 so that the viscous fluid stored in the metering section 30 flows into the first conduit 12 To the supply section 10 through the flow path (not shown).

The high-pressure gas unit 40 supplies the high-pressure gas to the metering section 30 through the third conduit 42 connected to the second conduit 20 to transfer the viscous fluid filled in the metering section 30 to the fourth conduit 56, To the mold (90).

The high-pressure gas unit 40 can be used as an alternative to a high-pressure gas unit used in a gas-injection injection molding apparatus. In this case, the manufacturing cost of the viscous fluid injection molding apparatus according to the present invention can be drastically reduced.

The metering section 30 is provided in the second conduit 20 to measure and fill the viscous fluid supplied from the supply pump 16 by a predetermined amount used in the mold 90. [

The metering section 30 preferably has a smaller storage capacity than the chamber 14.

 It is preferable that the metering section 30 is formed of a rigid reservoir to withstand the pressure applied to the high-pressure gas unit 40, which will be described later.

 The metering section 30 may be a water cylinder that supplies metered, stored viscous fluid by operating the piston with a high pressure gas of a bomb or high pressure gas unit 40.

The amount of the viscous fluid to be metered and stored in the metering section 30 is predicted in advance through experimentation and input through the operation panel or the like by the amount of the viscous fluid which is injected into the hollow part of the injection- And is controlled through the control unit 80.

That is, when the type of the injection-molded object to be injection-molded inside the mold 90 is changed, the amount of viscous fluid to be metered and stored in the metering unit 30 is determined again through the above-described experiment and inputting process. Accordingly, the amount of the viscous fluid metered and stored in the metering section 30 may vary depending on the type of the injection molding for forming the hollow portion.

The flow control unit 50 is provided in each of the second conduit 20 and the fourth conduit 56 to control the connection between the metering unit 30 and the supply unit 10 and between the metering unit 30 and the mold 90. [ do.

The flow control unit 50 is provided in the second conduit 20 and is opened when the viscous fluid returns from the metering unit 30 to the supply unit 10 and is blocked when the gas is supplied from the high pressure gas unit 40 A second open / close valve 52 provided in the third conduit 42 and intercepted when the viscous fluid is returned from the metering section 30 to the supply section 10 and opened when the gas is supplied from the high pressure gas unit 40; Valve < / RTI >

That is, in the modification process, the first on-off valve 52 is opened and the second on-off valve 54 is blocked, whereby the viscous fluid supplied from the supply portion 10 to the first conduit 12 So that it can not be moved to the fourth pipeline 56 and is stored in the metering section 30. [

The opening of the first opening and closing valve 52 causes the metering section 30 and the chamber 14 of the supplying section 10 to be connected to maintain the high pressure applied to the metering section 30 at atmospheric pressure, Or overflows into the chamber 14 when excessively viscous fluid is introduced into the metering section 30 due to misoperation of the fluid flow path 80 or other components.

The first opening / closing valve 52 is opened when the viscous fluid is filled in the metering part 30 and closes when the metering is finished. Thus, It plays a role of bringing the process stable.

The directional control valve 60 is connected to the fourth conduit 56 and installed at the inlet of the mold 90 to inject viscous fluid into the injection mold of the mold 90, .

The directional control valve 60 is preferably a three-way valve. Of course, the directional control valve 60 may be a different kind of valve as needed.

The control unit 80 is connected to and controls the feed pump 16, the high-pressure gas unit 40, the flow control unit 50, the direction control valve 60, and the injection unit 92 of the mold 90.

The fourth pipeline 56 is provided with a pressure sensor unit 58 for measuring the viscous fluid pressure measurement value supplied from the metering unit 30 through the high pressure gas unit 40 through the control unit 80.

The control unit 80 controls the viscous fluid supply pressure of the metering unit 30 when the viscous fluid pressure measurement value measured in the fourth duct is out of the range of the viscous fluid pressure reference value to be injected into the mold 90 through the pressure sensor unit The gas pressure of the high-pressure gas unit 40 is adjusted.

At this time, it is preferable that the viscous fluid pressure reference value injected into the mold 90 is formed to have a setting range of about 3,000 psi. Of course, the range of the viscous fluid pressure reference value injected into the mold 90 can be appropriately modified depending on the type of the injection object to be injected from the inside of the mold.

The controller 80 preferably determines the completion time of the injection molding of the mold 90 through the supply end of the injector 92 for supplying the synthetic resin to the mold 90 before operating the high pressure gas unit 40 .

The injection machine 92 is a supply unit for injecting injection synthetic resin (plastic) into the mold.

A purge section 70 for forcibly discharging the viscous fluid remaining in at least one of the inside of the direction control valve 60 and the inside of the mold 90 by the control section 80 and returning the viscous fluid to the supply section 10, Respectively.

The purge portion 70 includes a connection pipe 72 connected to the inlet of the mold 80, a valve 74 provided on the connection pipe 72 for opening and closing the connection pipe 72, An air supply part 76 provided at the entry side of the mold 90 or the direction control valve 60 for discharging the viscous fluid remaining in the mold 90 and the direction control valve 60; (Not shown).

3, the inlet side of the directional control valve 60 and the supply side of the mold 90 are opened (ON), and the connection of the fifth conduit 62 And the actuating valve 74 of the purge section 70 is turned off to close the connecting conduit 72. [

In this state, a high-pressure viscous fluid is injected into the mold 90 through the open side of the directional control valve 60, and a water injector (not shown) By injecting the viscous fluid, a hollow portion of the injection product is formed.

like this. Since the viscous fluid is used to form the hollow portion of the injection molding, it is possible to process a beautiful inner surface.

4, when the purge section 70 is operated, the inlet side of the direction control valve 60 is turned off, and the connection side of the supply side of the mold 90 and the side of the fifth conduit 62 are closed And the operation valve 74 of the purge section 70 is opened to open the connection pipe 72. [

In this state, when the high-pressure air is supplied from the air supply unit 76, the viscous fluid remaining in the interior of the mold 90 and the direction control valve 60 flows into the fifth channel 62 and the sixth channel 78 To the chamber (14) of the supply unit (10).

Although not shown in the drawings, the supply side of the mold 90 may be turned ON, and the connection side of the inlet side of the direction control valve 60 and the fifth conduit 62 may be OFF. In this case, only the viscous fluid remaining in the molded article of the mold 90 can be transferred to the chamber 14 of the supply unit 10 through the sixth channel 78 and the fifth channel 62 and recovered.

5 is an overall flowchart of a viscous fluid injection molding apparatus according to an embodiment of the present invention.

Hereinafter, a method of controlling a viscous fluid injection molding apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings.

2 and 5, before proceeding with the viscous fluid metering process, the first on-off valve 82 provided in the second conduit 20 is opened through the control of the controller 80, The second on-off valve 54 installed in the fourth pipe is turned off (S10)

The control unit 80 then activates the supply pump 16 of the supply unit 10 to supply the viscous fluid stored in the chamber 14 to the metering unit 12 through the first channel 12 and the second channel 20, (S20). Then,

At this time, the amount of the viscous fluid to be metered and filled in the metering section 30 is predicted through repetitive experiments to predict the amount of the viscous fluid to be injected into the hollow part of the injection molded product in the mold 90, And may be controlled through the control unit 80.

The control unit 80 determines the completion of the injection molding of the mold 90 through the supply end of the injector 92 that supplies the synthetic resin to the mold 90 before operating the high pressure gas unit 40. [ (S30)

3 and 5, the controller 80 cuts off the first on-off valve (OFF), opens the second on-off valve (ON), adjusts the direction Thereby regulating the opening of the valve 60.

The adjustment of the directional control valve 60 then opens the inlet side of the directional control valve 60 and the supply side of the mold 90 and blocks the connection side of the fifth conduit 62, The actuating valve 74 of the supporting portion 70 is turned OFF to close the connecting conduit 72. [

The control unit 80 operates the high pressure gas unit 40 so that the third pipeline 42, the second pipeline 20, the metering unit 30, the fourth pipeline 56, the direction control valve 60 And then injected into the injection mold of the mold to form a hollow portion. (S50)

Thereafter, the control unit 80 controls the viscous fluid pressure measured by the fourth pipeline 56 through the control of the pressure sensor unit 58 provided in the fourth conduit 56, And adjusts the supply gas pressure of the high-pressure gas unit 40 so as to adjust the viscous fluid supply pressure of the metering unit 30 when it is out of the range of the reference value (S60)

4 and 5, after the control unit 80 completes the injection of the mold 90, the adjustment of the direction control valve 60 and the operation of the purge unit 70 are performed to open the cavity of the mold 90 And the viscous fluid remaining inside the direction control valve 60 is recovered to the chamber 14 through the fifth pipeline 62 and the sixth pipeline 78 at step S70.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. I will understand.

Accordingly, the true scope of protection of the present invention should be defined by the following claims.

10: supply part 12: first channel
14: chamber 16: feed pump
20: second conduit 22: first check valve
30: Metering unit 40: High-pressure gas unit
42: third conduit 44: second check valve
50: flow control unit 52: first opening / closing valve
54: second open / close valve 56: fourth channel
58: Pressure sensor part 60: Direction control valve
62: fifth channel 70: purge section
72; Connection pipeline 74: Operation valve
76: air supply part 78: sixth channel
80: control unit 90: mold

Claims (14)

A supply unit connected to the first conduit to supply the stored viscous fluid;
A second conduit connected to the first conduit and returning the viscous fluid to the supply section;
A metering unit installed in the second conduit for metering and filling the viscous fluid supplied from the supply unit by a predetermined amount used in the mold;
A high pressure gas unit which supplies high-pressure gas to the metering unit through a third conduit connected to the second conduit, and transfers the viscous fluid filled in the metering unit to the mold via the fourth conduit;
A flow control unit installed in the second conduit and the fourth conduit for controlling the connection between the metering unit and the supply unit, the metering unit and the mold;
A direction control valve connected to the fourth conduit and provided at an inlet of the mold to inject viscous fluid into the injection mold of the mold or to switch after completion of injection and discharge the viscous fluid into the fifth conduit; And
And a control unit for controlling the supply unit, the high-pressure gas unit, the flow path control unit, and the direction control valve.
The method according to claim 1,
Wherein the supply unit includes:
A chamber for storing viscous fluid; And
And a supply pump provided at an outlet side of the chamber for supplying a predetermined amount of viscous fluid to the metering section.
The method according to claim 1,
Wherein the first channel is provided with a first check valve to prevent the viscous fluid supplied from the supply unit to the metering unit from flowing backward.
The method according to claim 1,
Wherein the metering unit is a cylinder for supplying a metered, stored viscous fluid by operating the piston with gas of the cylinder or the high-pressure gas unit.
The method according to claim 1,
Wherein the third channel is provided with a second check valve to prevent the viscous fluid returning from the metering unit to the supply unit through the second channel to flow back to the high pressure gas unit.
The method according to claim 1,
Wherein the control unit determines the completion time of the injection molding of the mold through the supply end of the injector for supplying the synthetic resin to the mold before operating the high-pressure gas unit.
The method according to claim 1,
A pressure sensor unit for measuring a viscous fluid pressure measurement value supplied from the metering unit through the high pressure gas unit through the control unit,
Wherein the control unit controls the pressure gauge unit to adjust the viscous fluid pressure of the metering unit when the viscous fluid pressure measurement value measured in the fourth conduit is out of the range of the viscous fluid pressure reference value to be injected into the mold through the pressure sensor unit, Wherein the supply gas pressure of the viscous fluid injection molding device is adjusted.
The method according to claim 1,
The flow-
A first opening / closing valve installed in the second conduit, opened when the viscous fluid returns from the metering section to the supply section, and blocked when the gas is supplied from the high pressure gas unit; And
And a second on-off valve installed in the third conduit and interrupted when returning the viscous fluid from the metering section to the supply section, and opened when gas is supplied from the high-pressure gas unit.
The method according to claim 1,
And a purge portion for forcibly discharging the viscous fluid remaining in at least one of the interior of the directional control valve and the interior of the mold, and for discharging the viscous fluid to the supply portion under the control of the control portion. .
10. The method of claim 9,
The purge portion
A connection pipe connected to an inlet of the mold;
A working valve installed in the connection pipe for opening and closing the connection pipe;
An air supply unit provided at an entrance side of the connection pipe to discharge the viscous fluid remaining in the mold or the direction control valve; And
And a sixth conduit having one end in the mold and the other end connected to the fifth conduit.
Closing the first on-off valve installed in the second conduit through the control of the control unit and blocking the second on-off valve installed on the fourth conduit;
The control unit activates the supply pump of the supply unit to meter the viscous fluid stored in the chamber to the metering unit through the first channel and the second channel,
Closing the first opening / closing valve, opening the second opening / closing valve, and regulating the opening of the direction adjusting valve installed at the inlet of the mold; And
The control unit operates the high-pressure gas unit and injects the high-pressure gas into the mold through the third pipe, the second pipe, the metering unit, the fourth pipe, and the direction control valve to form a hollow portion Of the viscous fluid injection molding apparatus.
12. The method of claim 11,
Wherein the control unit determines a time point at which the injection molding of the mold is completed through the supply end of the injector for supplying the synthetic resin to the mold before operating the high-pressure gas unit.
The method of claim 11, wherein
Wherein the control unit controls the viscous fluid pressure measured by the fourth pipe through the control of the pressure sensor provided in the fourth conduit to exceed the viscous fluid pressure reference value to be injected into the mold, Further comprising adjusting the supply gas pressure of the high-pressure gas unit to adjust the pressure of the high-pressure gas unit.
12. The method of claim 11,
After the injection of the mold is completed, the control unit operates the purge unit to recover the viscous fluid remaining in the hollow portion of the injection mold and in the direction control valve of the mold through the fifth pipe and the sixth pipe to the chamber Further comprising the step of injecting the viscous fluid.

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