KR101786101B1 - Device and method for manufacturing side garnish of vehicle - Google Patents

Abstract

The present invention relates to a multi-foaming injection molding method using Mucell, a counter-pressure and a core back method, which is a problem of existing micro-foaming method, To provide an apparatus and a method for manufacturing a side garnish for automobile using a multi-foaming injection method which is capable of maximizing the part weight by increasing the effective limit blowing rate to 30% within 10% of the ultrafine foaming method .

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a side garnish manufacturing apparatus and a method for manufacturing a side garnish for a vehicle using a multi-

The present invention relates to an apparatus and a method for manufacturing a side garnish for automobiles using a multi-foaming injection molding method, and more particularly, to an apparatus and a method for manufacturing side garnishes for automobiles using a multi- And more particularly, to an apparatus and a method for manufacturing a side garnish for a vehicle that can attain greater weight reduction by using a multi-foaming injection molding method.

Background Art [0002] A side garnish for a vehicle is a kind of injection ornament which is mounted over the front and rear doors of a vehicle to enhance the appearance of the vehicle.

Such side garnishes are manufactured by a general injection molding method, and are manufactured by applying a paint to ensure appearance.

4, the ultrafine foam plastic forming apparatus comprises a screw 12 rotatably arranged inside a cylinder 10, a screw 12 for rotatably supporting the upper end of the cylinder 10 in order to supply a plastic material into the cylinder, A heater 16 installed at the outer periphery of the cylinder 10 to melt the plastic material supplied into the cylinder 10 and a supercritical fluid CO ₂ or N include ₂₎ the supply supercritical fluid supply device 32, is arranged connected to the end nozzle portion of the cylinder 10, the injection mold 20, the melt is filled in the cavity (18 plastic containing the gas) is formed to such .

Therefore, when the plastic material is fed through the hopper 14, the plastic material is fed by the screw 12, the plastic material is melted by the heating of the heater 16 and the frictional heat by the screw, and the external supercritical fluid generator Supercritical fluid (CO ₂ or N ₂ ) supplied by the supercritical feeder 32 is introduced into the cylinder by the supercritical feeder 32 and kneaded with the already melted plastic material. That is, the plastic material melted in the cylinder is present in a state where supercritical fluid (CO ₂ or N ₂ ) injected from the outside is kneaded.

Subsequently, the kneaded molten plastic material is filled into the cavity 18 of the injection mold 20 by the rotation of the screw 12, so that the molten plastic material has a product shape. Supercritical fluid (CO ₂ or N ₂ ), which was present in the cylinder in the state of being kneaded with the plastic material, passes through the end of the injector nozzle and flows into the mold cavity 18 through the gate end where the filling starts. ₂ ), the pressure difference is suddenly changed due to the atmospheric pressure, and the supercritical fluid, which was present in the molten plastic resin due to the pressure difference, starts to generate foam nuclei, As the nucleus grows (the foaming pore grows), the foaming proceeds throughout the product. This is the basic principle of supercritical fluid (Mucell) that supercritical fluid (CO ₂ or N ₂₎ , which is present in the supercritical state, undergoes phase change to gas while exposing it to atmospheric pressure.

However, in the ultrafine foaming described above, when the molten plastic in which the supercritical fluid (CO ₂ or N ₂ ) is mixed is filled with the cavity of the injection mold, the foaming starts from the injection nozzle formed at the end of the cylinder, The size of the foamed cell is different between the periphery of the gate which is the cavity entrance of the cavity and the end of the foamed product, and unevenness of the cell size and unevenness of the product properties are generated as shown in the attached photograph (c) .

In addition, due to the resistance phenomenon during the resin flow, the problem of non-molding of the product itself occurs as shown in the picture (b) of FIG. 5 attached thereto, and because the resin flow and the mold temperature setting are not optimized, 5 (a), there is a problem of appearance deterioration that a gas mark or the like is generated on the surface.

In addition, since the cavity volume of the injection mold is determined, the foaming rate of the product is less than 10% in a limited cavity space, and the limitation of lightening due to the limited foaming ratio can not be overcome.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and it is an object of the present invention to provide a multi-foaming injection molding method using Mucell, a counter pressure and a core back method, In order to improve the defective appearance due to gas marks on the surface of the injection molded article, which is a problem of the ultra-micro foam method, and to increase the effective limit foam ratio within 10% of the micro foam method to 30% And an object of the present invention is to provide an apparatus and a method for manufacturing a side garnish for a vehicle using the method.

According to an aspect of the present invention, there is provided an injection molding apparatus including: a screw rotatably arranged in a cylinder; a hopper mounted on an upper end of the cylinder to supply a plastic material into the cylinder; A supercritical fluid supply device for supplying a supercritical fluid (CO ₂ or N ₂ ) in the cylinder; and a supercritical fluid supply device connected to the nozzle end of the cylinder for melting the plastic material fed into the cylinder, An external pressure controller capable of applying a predetermined pressure to the cavity formed by the stationary mold and the movable mold of the injection mold is installed on the side of the stationary mold or the movable mold, It is equipped with temperature sensor and pressure sensor which detects that plastic resin is fully charged in cavity in mold. A side garnish manufacturing apparatus for a vehicle using a multi-foaming injection molding method is provided.

According to another aspect of the present invention, there is provided a method of manufacturing an injection mold, comprising the steps of: moving a movable mold with respect to a stationary mold of an injection mold to form a cavity; A back pressure supplying step of supplying a gas as a pressure medium into the cavity in the external pressure controller so that the cavity internal pressure of the injection mold is maintained at 35 bar or more; A step in which a plastic molten resin into which a supercritical fluid (CO ₂ or N ₂ ) is kneaded is fed into a cavity of an injection mold; When the pressure or temperature of the plastic molten resin is sensed by the temperature sensor and the pressure sensor mounted on the end of the movable mold with the plastic molten resin being full, the pressure in the cavity is lowered to the atmospheric pressure by the external pressure controller. ; A core-backing step in which the pressure in the cavity is lowered to atmospheric pressure and the moving mold of the injection mold is finely formed; Cooling and ejecting the injection molded final product; The present invention also provides a method of manufacturing side garnish for automobiles using the multi-foaming injection molding method.

Through the above-mentioned means for solving the problems, the present invention provides the following effects.

According to the present invention, unlike the conventional microfabrication method in which the garnish product is injection-molded by using the multi-foaming injection method combined with the reverse back pressure method and the core bag method in the ultrafine foaming step, It is possible to prevent appearance defects due to gas marks and to maximize the part weight reduction by increasing the effective limit blowing rate up to 30% within 10% of the ultrafine foam forming method. In addition to the garnish, It is possible to reduce the weight and improve the fuel economy through the application.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing an automotive side garnish manufacturing apparatus using a multi-foaming injection molding method according to the present invention;
2 is a view for explaining a method of manufacturing a side garnish for a vehicle using the multi-foaming injection method according to the present invention,
Fig. 3 is a comparative diagram for explaining the cross-sectional structure of a product manufactured by the method of the present invention and a product produced by a general injection and ultrafine foaming method; Fig.
Fig. 4 is a schematic view showing a conventional microfabrication apparatus for producing a side garnish, Fig.
5 is a photograph explaining a problem of a conventional side garnish product;

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention relates to a method of foaming by pressure change when a resin is filled in a mold through a nozzle end of an injector cylinder in a state where a supercritical fluid (nitrogen gas) and a melted resin are kneaded in an injector cylinder in an ultra- There is a point in the point of reversing.

That is, according to the present invention, even if the pressure in the injection mold is pressurized to 35 bar or more to maintain the state where the supercritical fluid (N ₂ ) is not foamed, and the molten plastic resin in which the supercritical fluid is kneaded is filled in the cavity of the injection mold Counter pressure method in which the foaming is progressed in a state where the plastic resin is fully charged by simultaneously lowering the pressure in the cavity of the injection mold to the atmospheric pressure when the injection of the plastic resin into the cavity of the injection mold is completed, ) Construction method.

1, the apparatus for manufacturing garnish of the present invention comprises a screw 12 rotatably arranged inside a cylinder 10, a cylinder 10 for supplying a plastic material into the cylinder, A heater 16 installed at an outer periphery of the cylinder 10 to melt the plastic material supplied into the cylinder 10 and a heater 16 for supplying a supercritical fluid N ₂ A supercritical fluid supply device 32 and an injection mold 20 having a cavity 18 connected to the nozzle of the end of the cylinder 10 and filled with molten plastic containing gas, An external pressure controller 26 (for example, a gas booster) capable of applying a constant pressure is provided in the cavity 18 formed by the fixed mold 22 and the movable mold 24, and the movable mold 24 The temperature sensor and the pressure sensor 28 are mounted.

The external pressure controller 26 is connected to the movable mold 22 so as to be capable of providing pressure to the air passage 30 formed through the cavity 18 and electrically connected to the injector control panel 34 so as to exchange electric signals. 18 to be pressurized or depressurized.

At this time, as the pressure medium supplied by the external pressure controller 26, various gases may be used, for example, nitrogen or atmospheric air may be used.

A seal (not shown) made of soft rubber is attached to the outside of the parting line where the stationary mold 22 and the moving mold 24 of the injection mold 20 are in contact with each other to effectively implement the reverse back pressure method.

Considering that the foaming pressure in the plastic resin due to the supercritical fluid is 15 to 17 bar during the foaming process of the garnish product according to the present invention, the core back, By carrying out the process, additional foaming of the garnish product can be achieved without shrinkage and warping.

That is, when a mold is manufactured with a product thickness as small as about 30% of the basic design thickness of a garnish product, and the mold is finely opened after the resin filling is completed, if the mold is finely formed by 30% of the product thickness, It is possible to manufacture a garnish product which is finally conformed to the thickness designed in principle without irregular contraction or deformation of the product by the pressure.

Hereinafter, the garnish manufacturing method of the present invention will be described in more detail with reference to FIGS. 1 and 2 attached hereto.

The movable mold 24 is moved with respect to the stationary mold 22 of the injection mold 20 connected to the injection nozzle of the cylinder end to form the cavity 18 and the hopper 14 through when added to the plastic material as the plastic material transported by the screw 12 is melted by the heat and the screw frictional heat of the heater 16, the supercritical fluid to (N _2), a supercritical fluid supply device 32 for supplying Lt; RTI ID = 0.0 > supercritical < / RTI >

At this time, when a signal indicating completion of the mold-shaped body (metal mold coupling) is transmitted from the injector control panel 34 to the external pressure controller 26, the external pressure controller 26 causes the pressure medium A counter pressure process is performed in which the gas (nitrogen or air) is supplied to the injection mold 10 so that the internal pressure of the cavity 18 of the injection mold 10 is maintained at 35 bar or more for 3 to 5 seconds.

Subsequently, when a signal in which the pressure in the cavity 18 is maintained at a pressure of 35 bar is transmitted from the external pressure controller 26 to the injector control panel 34, the injector control panel is controlled to rotationally drive the screw 12, A solution in which the molten plastic in which the supercritical fluid is kneaded and the gas for foaming are mixed by the rotation of the screw 12 is supplied into the cavity 18 of the injection mold 20.

The height of the air flow path 30 where the air flow path 30 and the resin meet is limited to 1 to 3/100 mm so as not to allow the molten plastic resin to be filled to escape into the air flow path 30. By doing so, the pressure medium can freely be filled and discharged through the air passage 30, but the molten resin can be injection-molded into a desired shape by limiting the flow out of the cavity.

Subsequently, the plastic resin mixed with the foaming gas is filled in the cavity 18, and the temperature sensor and the pressure sensor 28 mounted to the movable mold 24, that is, the end of the movable mold 24 finally reaching the filled resin The external pressure controller 26 that receives the sensing signal senses the pressure of the resin in the cavity 18 and reduces the pressure in the cavity 18 to atmospheric pressure Control.

Accordingly, the pressure in the cavity 18 is lowered to the atmospheric pressure, and the movable mold 24 of the injection mold 10 is finely deformed.

More specifically, considering that the foaming pressure in the plastic resin by the supercritical fluid is 15 to 17 bar, the pressure in the cavity 18 is lowered to the atmospheric pressure, and the foaming of the plastic resin is started and at the same time, As the core back process is progressed as fine as the design thickness, the gauze product is further foamed without shrinking or twisting. As a result, the foaming rate of the product is increased from 10% to about 30%, thereby maximizing the weight of the product .

Thereafter, the product is taken out through the cooling process of the product.

As described above, by using the multi-foaming method in which the ultrafine foam process is performed and the counter pressure and the core back process are performed together, the conventional general injection Compared with the method of ultra-micro foam method, the pore size of the product can be uniformly formed by reverse back pressure process, the appearance defects can be improved, and the foam ratio can be increased up to 30% have.

In addition, all the processes of the present invention proceed sequentially within one cycle, and have a cycle time similar to that of a general injection process and an ultrafine foaming process, so that there is an advantage that a process time is not increased.

10: Cylinder
12: Screw
14: Hopper
16: heater
18: Cavity
20: Injection mold
22: Fixed mold
24: Moving mold
26: External pressure controller
28: Temperature sensor and pressure sensor
30: air flow
32: gas supply
34: Injector control panel

Claims (5)

A screw 12 rotatably arranged in the cylinder 10; a hopper 14 mounted on the upper end of the cylinder 10 for supplying a plastic material into the cylinder; A supercritical fluid supply device 32 for supplying a supercritical fluid (N ₂ ) into the cylinder 10; a supercritical fluid supply device 32 for supplying supercritical fluid (N ₂ ) to the cylinder 10; And an injection mold (20) having a cavity (18) connected to an end nozzle portion and filled with molten plastic containing gas,
An external pressure controller 26 for applying a constant pressure to the cavity 18 formed by the stationary mold 22 and the movable mold 24 of the injection mold 20 is installed on the side of the stationary mold 22, A temperature sensor and a pressure sensor 28 for sensing that the plastic resin is fully charged in the cavity 18 are mounted on the movable mold 24,
When the temperature sensor and the pressure sensor 28 are mounted on the end portion of the moving mold 24 to which the resin filled in the cavity 18 finally touches and the flow pressure or temperature of the resin is sensed, Wherein the received external pressure controller (26) controls the internal pressure of the cavity (18) to be reduced to the atmospheric pressure.
The method according to claim 1,
The external pressure controller 26 is connected to the movable mold 24 so as to be capable of providing pressure to the air passage 30 formed to pass through the cavity 18 and is electrically connected to the injector control panel 34 so as to be electrically signal- 18. The apparatus for manufacturing a side garnish for automobile according to claim 1,
The method according to claim 1,
Characterized in that a sealing made of soft rubber is attached to the outside of the parting line where the fixed mold (22) of the injection mold (20) and the moving mold (24) are in contact with each other.
Moving the movable mold (24) with respect to the stationary mold (22) of the injection mold (20) to form and connect the cavity (18);
Supplying a gas as a pressure medium into the cavity (18) in the external pressure controller (26) to maintain the internal pressure of the cavity (18) of the injection mold (10) at 35 bar or more;
A solution in which the plastic molten resin and the gas for foaming are mixed is supplied into the cavity 18 of the injection mold 20;
When the pressure of the plastic molten resin is detected by the temperature sensor and the pressure sensor 28 mounted on the end of the movable mold 24 while the plastic molten resin is fully charged in the cavity 18, ) So that the pressure in the cavity (18) is lowered to atmospheric pressure;
A core-backing step of finely bending the movable mold (24) of the injection mold (10) while the pressure in the cavity (18) drops to atmospheric pressure;
Cooling and ejecting the injection molded final product;
Wherein the method comprises the steps of: (1)
The method of claim 4,
Wherein the movable mold (24) is finely formed by the designed thickness of the product during the core backing step.

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