KR102223690B1 - Injection system and method for foam resin product - Google Patents

Abstract

The present invention relates to an injection system and method for molding a foamed resin. According to the present invention, after injecting high-pressure air into cavity while maintaining the surface temperature of the cavity at high temperature, during injection, the high-pressure air is discharged according to the amount of the resin, and then an injected-molded product is cooled. While creating pores inside the injection-molded product, and molding the surface of the injection-molded product to a high gloss, defects such as weld lines, flow marks, unmolding, parting lines, burrs, etc., are not caused due to deterioration of resin fluidity, thereby enabling molding of high-strength and light-weight foamed resin products.

Description

Injection system and method for foaming resin molding {INJECTION SYSTEM AND METHOD FOR FOAM RESIN PRODUCT}

The present invention relates to an injection system and method for molding a foamed resin, and after injecting high-pressure air into the cavity while maintaining the surface temperature of the cavity at a high temperature, and discharging the high-pressure air according to the amount of resin during injection, the injection product Is cooled to create pores inside the injection product, while molding the surface of the injection product with high gloss, and there are no defects due to deterioration of the fluidity of the resin such as weld line, flow mark, unmolded, parting line, burr, etc., high strength and light weight It relates to an injection system and method for molding a foamed resin that enables the molding of a foamed resin product of the present invention.

Foam injection molding is used as one of the methods for manufacturing door trims among automobile interior materials.

The foaming injection molding method can be classified into a chemical foaming method through a core back method and a physical foaming method in which supercritical gases (N₂, CO₂) are injected into an injection cylinder widely known as mucell foaming and mixed with a resin. have.

However, such chemical foaming or physical foaming could not be applied to molded products exposed to the outside, for example, automobile interior products, because foaming pores are generated on the product surface and the surface is not smooth with high gloss.

On the other hand, in the foam injection molding method for manufacturing the door trim, the injection material and the foaming agent are injected into the injection machine through the injection hopper of the injection machine, mixed and melted, and then the molten resin mixed with the foaming agent is injected into the mold. The foamed resin product is molded in such a way that it is opened (microscopically opened) and foamed.

However, in the foam molding method as described above, the moment the molten resin is injected into the cavity of the mold by high pressure, the resin is sporadically foamed due to the low pressure inside the mold, and the foaming gas contained in the molten resin penetrates into the resin layer of the base material. As pores are not formed and remain on the surface of the resin layer, the surface cannot be uniformly molded with high gloss, and surface roughness is deteriorated by generating flow marks, and burrs are generated.

Accordingly, a post-process for eliminating the above-described surface defects, for example, a painting process in which the surface is painted after removing the burrs is required, and the addition of such a factory causes an increase in cost, thereby reducing productivity.

As a related art, there are Registration Patent No. 10-0804064, Registration Patent No. 10-0465686, and the like.

Accordingly, the present invention was devised to solve the above problems,

To provide an injection system and method for foaming resin molding that can form high-strength and light-weight foamed resin products by molding the surface of the injection product with high gloss by stably generating pores inside the injection product while minimizing the decrease in the fluidity of the molten resin. The purpose.

In order to achieve the above object, the injection system for molding a foamed resin according to the present invention,

Heating means for supplying high-temperature pressurized hot water to the mold to increase the surface temperature of the mold cavity;

A pressurizing means for injecting high-pressure air into the cavity of the mold during injection to maintain the cavity at a constant high pressure, and discharging the high-pressure air according to the amount of the resin to be injected to maintain a constant pressure inside the cavity; And

It characterized in that it comprises a; cooling means for cooling the injection by supplying room temperature coolant to the mold.

And in the injection system for molding a foamed resin according to the present invention,

The heating means is characterized in that it comprises a proportional control valve or pulse valve for controlling the discharge of high-pressure air.

In addition, in the injection system for molding a foamed resin according to the present invention,

The heating means,

A high-pressure vessel that stores make-up water and recovered hot water,

A heating unit including a heater housing with a built-in heater, and a hot water generating tank having the heater housing built-in and forming a heating space,

It characterized in that it comprises a hot water pipe for circulating supply and recovery of hot water by connecting the high-pressure vessel and the heating unit and the mold.

In addition, the injection method for foaming resin molding according to the present invention,

a) increasing the surface temperature of the mold cavity by supplying pressurized hot water heated to a high temperature to the mold;

b) before injection, injecting and pressurizing high-pressure air into the cavity of the mold;

c) discharging the high-pressure air inside the cavity according to the amount of resin to be injected after the injection is started, thereby completing the injection while maintaining a constant pressure inside the cavity; And

c) cooling the injection product by supplying room temperature coolant to the mold; It characterized in that it comprises a.

The injection system and method for molding a foamed resin according to the present invention,

The mold cavity surface temperature is raised with pressurized hot water at a high temperature (approximately 180 degrees) to prevent the fluidity of the resin from deteriorating during injection, while the pressure of the high-pressure air inside the cavity during injection is reduced according to the amount of resin, so that the molten resin is reduced to the cavity. Foaming inside creates foaming pores, and then cooling the injection product with room temperature cooling water to mold the surface of the injection product to a high gloss while preventing defects such as weld lines, flow marks, unmolding, parting lines, burs, etc., high strength and light weight. The foamed resin product of can be molded, and accordingly, there is an effect of improving productivity since there is no need to perform a separate post-process after foam molding.

1 is a conceptual diagram schematically showing an injection system for molding a foamed resin according to the present invention.
Figure 2 is a cross-sectional view schematically showing a heating unit according to the present invention.
Figure 3 is a conceptual diagram schematically showing a pressing means according to the present invention.
Figure 4 is a conceptual diagram schematically showing an injection method for foaming resin molding according to the present invention.

The present invention will be described in detail in the text of the bar, implementation (態樣, aspect) (or embodiment) that can apply various changes and have various forms. However, this is not intended to limit the present invention to a specific form of disclosure, and it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

In each drawing, the same reference numerals, in particular the number of tens and ones, or the same reference numerals with the same tens, ones, and alphabet indicate members having the same or similar functions, and unless otherwise specified, each of the drawings. The member indicated by the reference numeral can be identified as a member conforming to these criteria.

In addition, components in each drawing are expressed by exaggeratingly large (or thick) or small (or thin) or simplified their size or thickness in consideration of the convenience of understanding, but the scope of protection of the present invention is limited by this. It shouldn't be.

The terms used in the present specification are only used to describe specific embodiments (sun, 態樣, aspect) (or embodiments), and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In the present application, terms such as ~comprise~ or ~consist~ are intended to designate the existence of features, numbers, steps, actions, components, parts, or a combination thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance the possibility of the presence or addition.

Unless otherwise defined, all terms used herein including technical or scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in the present application. Does not.

The ~1~, ~2~ and the like described in the present specification are only referred to to distinguish different constituent elements, and are not limited to the order of manufacture, and their names in the detailed description and claims of the invention It may not match.

In describing the injection system and method for foaming resin molding according to the present invention, for convenience, if an approximate rough direction standard is specified with reference to FIG. In the detailed description and claims related to the other drawings, unless otherwise specified, directions are specified and described in accordance with this standard.

Hereinafter, an injection system and a method for molding a foamed resin according to the present invention will be described with reference to the accompanying drawings.

The present invention relates to an injection system and method for molding a foamed resin,

First, the injection system for foaming resin molding according to the present invention, as shown in Figs. 1 to 3, a heating means 10 for improving the fluidity of the molten resin, a pressing means 20 for generating pores inside the injection product, It includes a cooling means 30 for preventing deformation of the injection product.

The heating means 10 supplies high-temperature pressurized hot water to the mold M to increase the surface temperature of the mold cavity C.

Specifically, the heating means 10,

High-pressure vessel (12) in which make-up water and recovered hot water are stored,

A heating unit 12 including a heater housing 12b in which a heater 12a is embedded, and a hot water generating tank 12c in which the heater housing 12b is embedded and forms a heating space,

And a hot water pipe for circulating supply and recovery of hot water by connecting between the high pressure vessel 12 and the heating unit 12 and the mold M.

Reference numeral 13, which is not described, is a hot water pump that pumps and circulates hot water through the first and second hot water pipes 14 and 15.

The high-pressure vessel 12 maintains the internal pressure at high pressure to prevent the high-temperature (approximately 180 degrees) fluid (water) heated to 100 degrees or more from evaporating into a gas. 80-90% of the total capacity is filled with fluid (water, etc.) and the rest is emptied to secure a space to be filled with high-pressure air discharged from the mold (M).

This high-pressure vessel 12 is connected to the make-up water tank 16, so that the make-up water pumped by the make-up water pump 17 is continuously supplied to the high-pressure vessel 12 through the forging check valve 18, so that the high-pressure vessel ( 12) Pressurized hot water is stored in a liquid state by replenishing the vaporized fluid while maintaining the internal pressure.

A water level sensor is installed in the make-up water tank 16 to generate a notification when the stored make-up water falls below a certain level to stop the pump.

The heating unit 12 heats the fluid (water) to a high pressure state when the hot water and make-up water stored in the high-pressure vessel 12 circulates along the second hot water pipe 15, and finally heats the fluid (water) to a high temperature of around 180 degrees. The pressurized hot water is supplied to the manifold (M1) of the mold (M) without vaporization.

A plurality of the heating units 12 are connected in series along the second hot water pipe 15,

Each of the hot water generating tanks 12c is mounted on a pipe with a flange 12A, and the fluid is stored in a heating space that is a space between the heater housing 12b and the hot water generating tank 12c.

When the hot water generating tank 12c is filled with fluid around the heater housing 12b, when the heater 12a directly heats the heater housing 12b, the heat of the heater housing 12b can absorb the fluid in the heating space. After heating, the heated fluid is circulated and discharged through the pipe.

In addition, the high-pressure vessel 12 is connected to the manifold (M1) of the upper and lower molds (M) and the heating unit (12) by a hot water pipe, the hot water pipe is a mold ( The first hot water pipe 14 connected to the mold (M) via both the high pressure vessel 12 and the heating unit 12 so that it is supplied to M) and then collected again, and the make-up water and hot water are supplied to the high pressure vessel 12 and It includes a second hot water pipe 15 to be heated by circulating between the heating units 12.

Each of the first hot water pipe 14 and the second hot water pipe 15 is provided with an opening/closing valve,

When the first on-off valve of the first hot-water pipe 14 is closed, the second on-off valve of the second hot-water pipe 15 is opened to heat the water circulating between the high-pressure vessel 12 and the heating unit 12 to a high temperature. Become,

When pressurized hot water in a liquid state is generated at a high temperature of 100 degrees or more (approximately 180 degrees), the first on/off valve is opened and the second on/off valve is closed, so that the hot water of the pressurized hot water of the heating unit 12 is manifold ( It is supplied as M1).

The pressurizing means 20 maintains the cavity C at a constant high pressure by injecting high-pressure air into the cavity C of the mold M during injection, and discharges the high-pressure air according to the amount of the resin to be injected into the cavity. (C) It includes a control valve 21 to keep the internal pressure constant.

Specifically, the pressurizing means 20 is composed of a compressor (not shown), an air regulator 22, a booster 23, and an air tank 24, and is a pneumatic pipe to the manifold (M1) of the upper and lower molds (M). The first pneumatic pipe (25) for injecting high-pressure air into the cavity (C) of the mold (M) and the second pneumatic pipe (26) for discharging the cooling water from the mold (M) to the cooling tower (31). ), wherein the first pneumatic pipe 25 is connected to the high pressure vessel 12 through the hot water line of the mold M, so that the high pressure air recovers the hot water in the mold M to the high pressure vessel 12. do.

Meanwhile, the control valve 21 is composed of a proportional control valve or a pulse valve.

The proportional control valve is a valve that automatically adjusts and controls air discharge in response to the amount of resin (pressure) in the cavity (C),

The MAC valve is a solenoid valve that controls air discharge by controlling an opening time based on the calculation of the amount of resin injected into the cavity C in advance.

The pressing means 20 forcibly maintains the pressure inside the cavity C at a constant pressure, so that the foaming gas cannot penetrate the resin layer and flows outside the resin layer, preventing the injection product from forming foam pores.

That is, when the molten resin is injected into the cavity (C), the molten resin is foamed in the cavity (C) at the moment when the rapid pressure drop of the molten resin occurs. The foaming gas does not penetrate into the resin layer and flows outside the resin layer, preventing the formation of foam pores.

The present invention maintains a constant pressure inside the cavity (C) in a high-pressure environment to prevent the molten resin flowing into the cavity (C) from being sporadically foamed at the beginning, so that the foaming pores are uniformly formed inside the injection product. do.

In addition, the pressurizing means 20 supplies high-pressure air to each of the hot water pipe 14 and the cooling pipe 33 to discharge hot water and cooling water to the outside of the mold (M).

The cooling means 30 cools the injection by supplying coolant at room temperature to the mold M, and includes a cooling tower 31 and a coolant pump 32 in which coolant at room temperature is stored, and includes a cooling pipe 33 It is connected to the manifold (M1) of the mold (M) through.

At this time, the cooling line of the mold (M) is formed close to the surface of the cavity (C) to rapidly cool the cavity (C), and a second pneumatic pipe (26) is connected to the cooling pipe (33), and the pressurizing means (20) The cooling water supplied to the mold (M) is discharged to the outside.

The coolant pump 32 is connected to a pressure switch (not shown) to generate a notification when the water pressure of the coolant is not detected, thereby stopping the operation of the pump.

Next, an injection method for molding a foamed resin according to the present invention will be described with reference to FIGS. 1 to 4.

The injection method for molding a foamed resin of the present invention,

a) increasing the surface temperature of the mold cavity (C) by supplying pressurized hot water heated to a high temperature to the mold (M);

b) before injection, injecting and pressurizing high-pressure air into the cavity (C) of the mold (M);

c) Completing the injection in a state where the pressure inside the cavity (C) is kept constant by discharging the high-pressure air inside the cavity (C) according to the amount of resin to be injected after the injection is started; And

c) cooling the injection product by supplying room temperature coolant to the mold (M); Includes.

In step a), the pressurized hot water is heated while supplemental water (and recovered hot water) circulates through the heating unit 12 along the second hot water pipe 15, and at this time, the high-pressure vessel 12 is heated due to circulation heating. Circulating heating of water is continued while the pressure inside the high-pressure vessel 12 is maintained at high pressure by continuing to supply supplemental water as much as the amount of water vaporized, and accordingly, the water heated to an ultra-high temperature around 180 is not vaporized and is in a liquid state. Keep it.

When water is heated to around 180 degrees by circulation heating in such a high-pressure environment, after the mold closing operation of the injection machine is performed, the second hot water pipe 15 is closed and the first hot water pipe 14 is opened, and the pressurized hot water It is supplied to the mold (M).

The pressurized hot water supplied to the mold (M) increases the surface temperature of the cavity (C) while circulating along the first hot water pipe (14). 15) is heated while recirculating again to offset the drop in temperature.

And when the surface temperature of the cavity C reaches the set temperature, a pressurization signal is transmitted to the pressurizing means 20, and when the inside of the cavity C reaches the set pressure by opening the high-pressure sol valve, the high-pressure sol valve is closed, and the b ), the pressurization of the cavity (C) is completed.

When the pressurization of the cavity (C) is completed, as step c), the injection machine injects the molten resin into the cavity (C).

At this time, after the injection starts, the control valve 21 opens the valve according to the amount of resin injected into the cavity C so that the inside of the cavity C is always maintained at a constant pressure during injection, and the high pressure air inside the cavity C Discharge.

For example, in the case of a proportional control valve, the real-time pressure (amount) of the injected resin and the air pressure inside the cavity (C) are calculated together, and as the amount of resin injected into the cavity (C) increases, the cavity (C) By sequentially discharging the high-pressure air, the pressure inside the cavity (C) is kept constant.

In addition, after calculating the amount of resin per hour injected into the cavity (C) according to the injection conditions, the MAC valve is adjusted by changing the opening time of the MAC valve according to the injection time in consideration of the amount of air discharged per hour of the MAC valve itself. While doing so, the high-pressure air in the cavity (C) is discharged, so that the pressure inside the cavity (C) is kept constant.

And just before injection is completed (for example, 0.01 seconds before completion), the control valve 21 is completely opened and the high-pressure air inside the cavity (C) is forcibly exhausted, and the injection is performed while the cavity (C) is depressurized to atmospheric pressure. It is completed.

When the injection is completed in this way, the high-pressure air discharged to the control valve 21 and a part of the high-pressure air supplied to the pressurizing means 20 are turned to the first hot water pipe 14, and the pressurized hot water in the mold M is transferred to the high-pressure vessel 12. ), and the high-pressure air recovered by the high-pressure vessel 12 is recovered by the air tank 24 of the pressurizing means 20 while naturally exhausted by additional supplemental water.

When the discharge of hot water is completed, the cooling means 30 operates in step c) to circulate room temperature cooling water to the mold M, and the cooling water circulating in the mold M cools the injection product to a certain temperature or less. .

When a predetermined cooling time has elapsed, the injection machine allows the injection to be ejected through the mold opening and retraction operation of the core or the operation of the push pin, which is the same as a known injection method, and thus a detailed description thereof will be omitted.

In the injection-molded foamed resin injection product, the foaming gas generated during injection does not flow outside the resin layer and penetrates into the resin layer to form foam pores. At this time, the heating means 10 is used to form the cavity of the mold M. (C) is maintained in an ultra-high temperature environment to offset the decrease in flowability of the resin caused by the high pressure environment inside the cavity (C).

Therefore, the foamed resin product molded in this way increases the fluidity of the resin at the surface temperature of the cavity (C) at an ultra-high temperature, so that the foam pores are not exposed to the surface of the injection product, so that the surface of the injection product is molded with high gloss, as well as weld lines and flow marks , Underforming, parting lines, burrs, etc. do not occur.

After the injection is completed, the cavity (C) in the ultra-high temperature environment is rapidly cooled through the cooling means (30), and the injection product is cooled, so that high-strength and lightweight foamed resin products can be molded without deformation of the injection product. do.

On the other hand, the heating unit 12, if the heater (12a) burns out, the heater housing (12b) and the hot water generating tank (12c) are permanently used as it is, and only the heater (12a) in the interior needs to be replaced. If it occurs, after discharging the water, the hot water generating tank 12c fixed to the flange 12A is separated, and the scale in the heater housing 12b is removed and reused.

In describing the present invention above, the injection system and method for foaming resin molding have been mainly described with reference to the accompanying drawings, but the present invention can be various modifications, changes and substitutions by those skilled in the art. It should be construed as falling within the scope of the invention.

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M: Mold M1: Manifold
C: cavity
10: heating means 11: high pressure vessel
12: heating unit 13: hot water pump
14: first hot water pipe 15: second hot water pipe
16: make-up water tank 17: make-up water pump
18: forged check valve
20: pressurizing means 21: control valve
22: regulator 23: booster
24: air tank 25: first pneumatic pipe
26: 2nd pneumatic pipe
30: cooling means 31: cooling tower
32: cooling water pump 33: cooling pipe

Claims (4)

A heating means (10) for supplying high-temperature pressurized hot water to the mold (M) to increase the surface temperature of the mold cavity (C);
During injection, high-pressure air is injected into the cavity (C) of the mold (M) to maintain the cavity (C) at a constant high pressure, but the pressure inside the cavity (C) is constant by discharging the high-pressure air according to the amount of resin to be injected. A pressurizing means (20) including a control valve (21) for maintaining the pressure; And
Including; cooling means 30 for cooling the injection product by supplying room temperature cooling water to the mold (M),
The heating means 10,
High-pressure vessel (12) in which make-up water and recovered hot water are stored,
A heating unit 12 including a heater housing 12b in which a heater 12a is embedded, and a hot water generating tank 12c in which the heater housing 12b is embedded and forms a heating space,
And a hot water pipe connected between the high pressure vessel 12 and the heating unit 12 and the mold M to circulate and recover hot water,
The inside of the high-pressure vessel 12 is filled with 80 to 90% of water compared to the total capacity, and the rest is emptied to secure a space to be filled with the high-pressure air discharged from the mold M, thereby increasing the pressure inside the high-pressure vessel 12. To prevent vaporization of hot water heated above 100 degrees
The hot water pipe includes a first hot water pipe 14 connected to the mold M via both the high pressure vessel 12 and the heating unit 12, and the high pressure vessel 12 and the heating unit 12 for supplemental water and hot water. It includes a second hot water pipe 15 to be heated by circulating between,
A plurality of the heating units 12 are connected in series along the second hot water pipe 15,
Each hot water generating tank 12c is mounted on a pipe with a flange 12A to store water in a heating space, which is a space between the heater housing 12b and the hot water generating tank 12c,
The hot water generating tank 12c is filled with water around the heater housing 12b, while the heater 12a directly heats the heater housing 12b, while the heat of the heater housing 12b heats the water in the heating space. After that, the heated water is circulated and discharged through the pipe,
Each of the first hot water pipe 14 and the second hot water pipe 15 is provided with an opening/closing valve,
When the first opening/closing valve of the first hot water pipe 14 is closed, the second opening/closing valve of the second hot water pipe 15 is opened so that the water circulating between the high pressure vessel 12 and the heating unit 12 is high temperature. Is heated to
When the pressurized hot water in a liquid state is generated at a high temperature of 100 degrees or more, the first on-off valve is opened and the second on-off valve is closed, so that the pressurized hot water of the heating unit 12 is supplied to the manifold M1 of the mold Characterized by,
The pressurizing means 20 is composed of a compressor, an air regulator 22, a booster 23, and an air tank 24, and is connected to the manifold (M1) of the upper and lower molds (M) by pneumatic pipes. A first pneumatic pipe 25 for injecting high-pressure air into the cavity C of M) and a second pneumatic pipe 26 for discharging the cooling water of the mold M to the cooling tower 31. 1 The pneumatic pipe 25 is connected to the high-pressure vessel 12 through the hot water line of the mold M, so that the high-pressure air recovers the hot water in the mold M to the high-pressure vessel 12. Injection system.
The method of claim 1,
The control valve (21) is an injection system for foaming resin molding, characterized in that it comprises a proportional control valve or a pulse valve for controlling the discharge of high-pressure air.
The method of claim 1,
The high-pressure vessel 12 is connected to the make-up water tank 16, and the make-up water pumped by the make-up water pump 17 is continuously supplied to the high-pressure vessel 12 through the forging check valve 18. Injection system for resin molding.
The method of claim 1,
The cooling means 30 includes a cooling tower 31 and a cooling water pump 32 in which coolant at room temperature is stored, and is connected to the manifold M1 of the mold M through a cooling pipe 33 Injection system for foaming resin molding.

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