KR20170123942A - Pressurization mold for injection molding - Google Patents

Abstract

The present invention relates to a pressurizing mold for injection molding. A separate material drying process can be skipped by remarkably reducing a surface defect rate by pressurizing the inside of a core during injection molding using a resin material in a non-dry or semi-dried state. The pressurizing mold comprises: a first template part (110); a second template part (130); an ejector pin (150); and a compressor part (160).

Description

[0001] PRESSURIZATION MOLD FOR INJECTION MOLDING [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a mold for injection molding, and more particularly, to a mold for injection molding, which is capable of reducing the surface defect rate by pressing the core during injection molding using a resin material of non- To a press mold for molding.

Injection molding (injection molding) is a method of producing products from various resins as a raw material, and it is advantageous in mass production of products requiring high precision. Demand is continuously increasing with the development of mold technology.

Such injection molding comprises a step of heating a raw material to which a pigment, a stabilizer, a plasticizer, a filler, and the like are added to a synthetic resin in a molten state at a high temperature, injecting the resin into a mold through a cylinder and a screw, and then solidifying.

In this case, as the raw material is injected into the injection cavity at a relatively low temperature under atmospheric pressure through the high-temperature plasticizing process, water contained in the raw material is vaporized or gas is generated, which impedes adhesion to the resin flow and mold, The quality of the surface defects due to gas and bubbles is degraded, and the appearance defects of such products cause defective products by affecting post-processing coating, plating, coating, and deposition.

There is a conventional technique for solving such a problem, for example, there is a method of sufficiently drying a resin used as a raw material before melting. However, since a separate apparatus for drying the raw materials must be provided, there is a disadvantage in that the cost of the product is increased due to high initial cost and increased power consumption and maintenance cost due to driving, and even if the drying time of the raw material is long, There is still a small amount of water remaining in the mold, and there is still a problem that the surface quality of the product is deteriorated due to the gas generated according to the characteristics of the chemical raw material.

Korean Patent Laid-Open No. 10-2008-0020774 (published on Mar. 6, 2008)

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a method of manufacturing an injection molding machine, which is capable of preventing the occurrence of surface defects due to steam and gas generated in molten raw materials, So that a complete sealing of the sliding portion can be achieved without using a pressing mold.

In order to achieve the above-mentioned object, the present invention provides a mold having a hopper to which a raw material is supplied and a heater for melting a raw material to supply a molten raw material in communication with an injection portion for pressurizing and supplying molten raw material, A first type plate part connected to the injection part to receive a raw material and having a first core formed therein to form one side of the cavity; And a second core formed with a gas channel connecting the cavity and the gas runner, the second core being formed with the other side of the cavity in contact with the first core with the coating layer formed thereon, A second through-hole for communicating the cavity to the outside, and a pressurizing hole communicating the gas runner with the outside; An ejector pin inserted into the first through hole and pushing a molding inside the cavity by sliding motion, the coating layer being formed on an outer circumferential surface; A compressor unit for supplying compressed air to the gas runner through the pressurizing hole; .

Wherein the gas channel has a sectional shape curved along the cavity side from the bottom, a regulator is provided for controlling a change in pressure between the compressor and the pressurizing hole, and the second template portion is communicated from the outside, And a first bubble providing unit configured to inject the generated high-pressure air into the gas channel.

In addition, the second template portion may include a pressurizing chamber formed at a contact portion with the second core so as to be separated from the cavity, the pressurizing chamber passing through the first through-hole, the second through-hole communicating with the pressurizing chamber, The ejector pin may further include a second bore providing a communication between the pressurizing chamber and a side end surface of the cavity.

Further, the gas channel is formed in each curved portion of the cavity, and the pressurizing hole is formed for each gas channel.

Further, it is preferable that the coating layer is made of titanium aluminum nitride plating.

The injection cavity can be pressurized during injection molding according to the present invention to suppress the generation of moisture and residual gas of vaporization of the additive, thereby eliminating defects such as surface bubbles and swelling. In addition, it is possible to omit moisture removal and drying process in the raw material, which has been performed in the prior art, thereby shortening the process and reducing the cost due to the drying equipment, while improving the surface quality of the product.

1 is a side sectional view showing the structure of an injection molding machine according to the present invention,
FIG. 2 is a side sectional view showing a state of a mold according to a first embodiment of the present invention,
FIG. 3 is a first partial perspective view showing the structure of a second core and an ejector pin according to a first embodiment of the present invention, FIG.
4 is a second partial perspective view showing the structure of a first core and a second core according to the first embodiment of the present invention,
5 is a side sectional view showing a state of a mold according to a second embodiment of the present invention,
6 is a partial perspective view showing a structure of a second core according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the structure of a pressurizing die for injection molding of the present invention will be described in detail with reference to the accompanying drawings.

1 is a side sectional view showing a structure of an injection molding machine according to the present invention.

The present invention is basically applied to a mold of an injection molding machine. In this injection molding machine, an injection part 101 provided with a hopper for supplying a raw material and a heater for melting the supplied raw material and pressurizing and supplying the molten raw material is provided And the molds are coupled to each other to form an injection cavity C, and a supply hole 111 communicating with the injection part 101 on one side to receive a molten material is formed.

Since the injection unit 101 is substantially the same as that of a conventional injection molding apparatus in which various resin materials are melted at a high temperature and injected at a high pressure, a detailed description thereof will be omitted in order to prevent blurring of the gist of the present invention.

FIG. 2 is a side sectional view showing a state of a mold according to a first embodiment of the present invention, FIG. 3 is a first partial perspective view showing the structure of a second core and an ejector pin according to a first embodiment of the present invention, 2 is a second partial perspective view showing the structure of a first core and a second core according to a first embodiment of the present invention. The present invention mainly comprises a first type plate portion 110, a first core 120, A second core plate 140, an ejector pin 150, and a compressor unit 160 are provided.

The first core 120 and the second core 140 are provided with the first core 120 and the second core 140 forming the injection cavity C basically with each other, Shaped plate portion 110 and a second-type plate portion 130. [

At this time, a supply hole (111) connected to the injection part (101) and supplied with molten raw material is formed on one side of the mold so that the molten raw material can be pressurized and filled in the cavity (C) The compressed air is supplied from the outside of the cavity C to the inside of the cavity C to increase the internal pressure of the cavity C. [

2, a supply hole 111 is formed on the side of the first type plate portion 110 and a pressure inside the cavity C is increased toward the side of the second type plate portion 130 , The position of the ejector pin 150 for separating the molded product is formed on the side of the second-type plate portion 130 on the side opposite to the supply hole 111. [ In most injection molding, the position of the ejector pin 150 is the same, but the shape of the core including the position of the supply hole 111 may be variously modified to reflect the shape of the product.

The first core 120 and the second core 140 are detachably attached to the first and second plates 110 and 130 so that the core can be replaced and repaired The first type plate portion 110 is fixed and the second type plate portion 130 is movable so as to move the movable second type plate portion 130 to move the first core 120 And the second core 140 are joined together by a hydraulic or pneumatic or electromechanical operation unit.

That is, the first core 120 is injected into the hopper through the injection part 101 in a fixed state to inject molten resin, and the second core 140 can reciprocate within a predetermined interval in a horizontal direction So as to form the other side of the injection product while being in contact with the first core 120. At this time, a special coating layer is formed on the contact portion of the first core 120 and the second core 140 without a separate packing means, so that the leakage of the raw material to the cavity C is prevented from occurring, A cooling water passage for cooling and solidifying the high temperature resin injected into the cavity C may be formed in the second core 120 and the second core 140.

Also, in the present invention, the second core 140 is formed with a gas runner 141 on the side of the cavity C. The gas runner 141 is a portion through which the compressed air for pressurizing the cavity C is introduced and the cavity C and the gas runner 141 are connected through a gas channel 142 having a relatively small depression degree So that the inside of the cavity C can be pressed through the compressed air on the gas runner 141 side.

When the gas runner 141 and the gas channel 142 are partially formed and the partial pressurization is performed, as the compressed air is supplied to the cavity C, the gas runner 141 and the gas channel 142 are not formed The gas runner 141 and the gas channel 142 are continuously formed along the outer side of the cavity C as shown in the attached drawings so that the uniform uniform pressurization of the cavity C And the like.

The gas channel 142 may be formed to surround the outer side of the cavity C with the gas runners 141 and 142. In addition, So that the compressed air is applied to the cavity (C) but the raw material does not escape.

A pressurizing hole 134 continuously penetrating the second core 140 to communicate with the gas runner 141 so as to supply compressed air to the gas runner 141 is formed in the second- .

A first through hole 132 is formed through the second core 140 for communicating the cavity C to the outside so as to insert the ejector pin 150, Is inserted into the first through hole (132) and is slidably moved, thereby pushing the molded product in the cavity (C).

That is, one end of the ejector pin 150 is located in the same or slightly recessed state as the inner wall surface of the cavity C formed in the second core 140 during injection, and is pushed through a separate driving means in a state in which molding is completed So that the molded product can be smoothly separated from the second core 140 by pushing out the molded product.

Particularly, in the present invention, a coating layer for sealing is formed on the outer circumferential surface of the ejector pin 150 and the inside of the first through hole 132. This facilitates smooth sliding while minimizing the gap between the ejector pin 150 and the second core 140 or the second plate part 130, so that the molten raw material or air can flow through the wetting gap of the ejector pin 150 This is a method for preventing leakage.

Conventionally, a packing means such as an O-ring has been used to slide and close the ejector pin 150. However, due to environmental factors such as high temperature transferred from the raw material and frequent slide operation, The life of the O-ring of the material is shortened, and the replacement is frequent due to the breakage. In the present invention, this problem is solved through a special coating layer having excellent abrasion resistance and abrasion resistance.

The coating layer applicable for this purpose is titanium nitride aluminum (TiAIN), titanium nitride (TiN), chromium nitride (CrN), titanium carbonitride (TiCN), and zirconium nitride (ZrN), which are excellent in wear resistance and corrosion resistance, It is preferable to use titanium aluminum which can be used.

The titanium nitride aluminum coating film used in the present invention has a hardness Hv 200 to v 500 and a coating film thickness of 2 to 3 탆 (on the side), which is formed by spraying the coating liquid onto the surface and drying at a temperature of 500 캜 or less. Thereby effectively preventing the adhesion of the plastic raw material and the core, as well as the stable sealing performance and the reduction of the frictional resistance.

In addition to the ejector pins 150, the same coating layer can be formed on all portions where contact and friction occur, such as the contact surfaces of the first core 120 and the second core 140 mentioned above.

The compressor unit 160 is configured to supply compressed air to the gas runner 141 through the pressurizing hole 134. The compressor unit 160 includes a separate electric compressor installed in the injection molding apparatus in a built-in manner, and a high-pressure compressed air And a storage tank 161 for storing the second plate portion 130 and the ejector pin 150. The means for moving the second plate portion 130 and the ejector pin 150 in association with the second plate portion 130 and the ejector pin 150 is also constructed by a pneumatic driving method. In addition, a solenoid valve (V) that is opened and closed by a control signal is provided on a pipe connecting the storage tank (161) and the gas runner (141) to control supply of compressed air.

In addition, a regulator 162 for regulating the pressure of compressed air is provided in the pipe connecting the storage tank 161 and the gas runner 141, so that the depressurized air is supplied appropriately while preventing the sudden supply of high- In the initial stage in which the molten resin is injected into the cavity (C) through a means capable of electronically controlling the control pressure of the regulator (162), a weak pressure is applied and the injection amount of the molten resin The pressure applied to the first core 120 and the second core 140 can be gradually increased so that effective pressurization can be achieved without the material being pushed in at the interface between the first core 120 and the second core 140, .

FIG. 5 is a side sectional view showing a state of a mold according to a second embodiment of the present invention, and FIG. 6 is a partial perspective view showing a structure of a second core according to a second embodiment of the present invention.

In the second embodiment of the present invention, the gas runners 141 are formed in the form of a loop along the outside of the cavity C, while the gas channels 142 are partially formed instead of the same loop. At this time, the formation position of the gas channel may vary depending on the shape of the cavity, but it is preferable that the gas channel is formed concentrically on the curved portion of the cavity C, It is preferable that the same number of pressure holes 134 as the gas channels 142 are formed corresponding to the positions of the gas channels 142.

As described above, since a gap for compressed air is formed between the cavity C and the gas channel 142, there is a possibility that the molten resin seeps through the gap. In addition, Or may remain. If it is attached to the molded product, it can be easily removed by post-treatment such as polishing after the molding is completed, but in some cases, the part may fall off and remain in the core or gas channel 142, Or it is an element that can cause defects by blocking the gas channel 142, so it is necessary to remove it every step.

In the second embodiment of the present invention, the second plate portion 130 penetrates the second core 140 to communicate with the outside from the outside, and pressurizes the high-pressure air generated through the compressor portion 160 into the gas channel 142, And a first brewing part 135 which is formed so as to blow out the residue by spraying inward. In other words, the high pressure air is injected through the first catheter 135 to remove remaining fine resin and foreign matter, so that the gas channel 142 prevents the removed resin from being blown into the cavity C, And has a cross-sectional shape curved along the cavity C side. Further, air flows outward along the curved wall with the air blowing direction of the first pouring unit 135 toward the cavity (C) side so that fine resin and foreign matter scattered outwardly are released .

In addition, in the second embodiment of the present invention, high pressure air is injected from the inside of the cavity C through the ejector pin 150 to the outside to escape the scattered residue to the outside, and to help the removal of the core.

The second mold plate 130 is provided with a pressurizing chamber 131 having a predetermined volume so as to be separated from the cavity C at a contact portion with the second core 140, And a second through hole 133 connected to the storage tank 161 through the outside is formed on a side surface of the pressurizing chamber 131.

In addition, a second small bore 151 for communicating the pressurizing chamber 131 from the outer peripheral surface of the end portion is formed in the ejector pin 150 for air injection through the ejector pin 150.

That is, the second small bore 151 formed inside the ejector pin 150 having a cylindrical shape has a shape in which the end of the ejector pin 150 in the direction in which the cavity C is located at the position of the ejector pin 150 for separating the molded product Is formed along the inside of the ejector pin (150) so as to communicate from the outer peripheral surface to the pressurizing chamber (131). Even if compressed air is supplied to the pressurizing chamber 131 through the second through-hole 133 during the injection, the second cryogen 151 is kept closed by the second core 140, As the ejector pin 150 slides due to the release of the product or the like, the second cuvette 151 is opened so that the compressed air in the pressurizing chamber 131 is ejected to the outside of the cavity C, do.

It will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present invention as defined by the appended claims and their equivalents. It can be seen that deformation can be made.

101: injection part 110: first type plate part
111: supply hole 120: first core
130: second type plate part 131: pressure chamber
132: first through hole 133: second through hole
134: Pressurizing ball 135: First serving
140: second core 141: gas runner
142: gas channel 150: ejector pin
151: second sub-unit 160: compressor unit
161: Storage tank 162: Regulator
C: Cavity V: Valve

Claims (5)

A mold (C) having a hopper to which a raw material is supplied and a heater for melting a raw material to communicate with an injection part (101) for pressurizing and supplying molten raw material to receive a raw material in a molten state,
A first type plate part 110 connected to the injection part 101 to receive a raw material and provided with a first core 120 forming one side of the cavity C inward;
A gas runner formed on the side of the cavity C to form the other side of the cavity C by abutting against the first core 120 with a coating layer formed thereon, A first through hole 132 for communicating the cavity C to the outside and a second through hole 132 for communicating the gas channel 141 with the outside, A second type plate part 130 having a pressurizing hole 134;
An ejector pin (150) inserted into the first through hole (132) and pushing the molding inside the cavity (C) by sliding, the coating layer being formed on the outer peripheral surface;
A compressor unit 160 for supplying compressed air to the gas runner 141 through the pressurizing hole 134; And a mold for injection molding.
The method according to claim 1,
The gas channel 142 has a cross-sectional shape curved along the cavity C from the bottom,
A regulator 162 for controlling the pressure change between the compressor unit 160 and the pressurizing hole is provided,
The second plate portion 130 may further include a first bore providing portion 135 communicating from the outside and configured to inject high pressure air generated in the compressor portion 160 into the gas channel 142 And a mold for injection molding.
3. The method of claim 2,
The second mold plate 130 includes a pressurizing chamber 131 formed at a contact portion with the second core 140 so as to be separated from the cavity C and through which the first through hole 132 passes, Further comprising a second through hole (133) communicating with the compressor unit (131) and connected to the compressor unit (160)
Wherein the ejector pin (150) further comprises a second boss (151) for communicating the end surface of the pressurizing chamber (131) and a side of the cavity (C).
The method according to claim 1,
Wherein the gas channel (142) is formed in each curved portion of the cavity (C), and the pressure hole (134) is formed for each gas channel.
The method according to claim 1,
Wherein the coating layer is made of titanium aluminum nitride plating.

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