KR102189555B1 - Injection mold structure for reducing gate loss and injection molding method using the same - Google Patents

Abstract

Disclosed are an injection mold structure for reducing gate loss and an injection molding method. According to an aspect of the present invention, provided is an injection mold structure, including: an upper mold; a lower mold that forms a cavity in which an injection product is molded between the upper mold; a heat insulating layer disposed on the upper part of the upper mold; an upper structure disposed on the upper part of the heat insulating layer; a nozzle extending downward from the upper structure and supplying a resin for molding the injection product into the cavity; and an insulating block disposed at the lower part of the nozzle. According to another aspect of the present invention, an injection molding method is provided in which an injection product is molded using an injection mold structure, and a gate is formed within a height range corresponding to the cavity at a lower part of an insulating block. The present invention can reduce the height of the gate generated during injection by improving the structure of the upper mold and the nozzle, thereby significantly reducing material loss.

Description

Injection mold structure for reducing gate loss and injection molding method using it {INJECTION MOLD STRUCTURE FOR REDUCING GATE LOSS AND INJECTION MOLDING METHOD USING THE SAME}

The present invention relates to an injection mold structure for molding an injection product such as an O-ring, and an injection molding method using the same.

Injection molds are widely used as a method of injecting molten resin into a mold and making a product by hardening it in an injection machine.

(A) of FIG. 1 illustrates an O-ring product as an example of an injection product, and (b) illustrates a gate shape generated when the O-ring is injected as shown in (a).

Referring to FIG. 1, in general, during injection molding, a gate G serving as an injection path for a resin is formed together with the product P, and the gate G is appropriately removed through post-processing such as finishing. The gate G has a shape that extends to a predetermined height as generally shown for sufficient insulation between the cavity in which the product P is molded and the flow path into which the molten resin is injected. However, since the gate G is a part that is removed from the final product P, it causes a loss of material or an increase in manufacturing cost in terms of raw materials.

Registered Utility Model Publication No. 20-0371945 (registered on Dec. 23, 2004)

Embodiments of the present invention are to provide an injection mold structure capable of reducing gate loss while maintaining insulation between a cavity and a flow path, and an injection molding method using the same.

According to an aspect of the invention, the pictograph; A lower mold forming a cavity in which an injection product is molded between the upper mold; A heat insulating layer disposed on the upper part of the upper mold; An upper structure disposed on the heat insulating layer; A nozzle extending downward from the upper structure and supplying a resin for molding the injection product into the cavity; And an insulating block disposed at the bottom of the nozzle; including, an injection mold structure may be provided.

According to another aspect of the present invention, an injection molding method may be provided in which an injection mold is formed using an injection mold structure, and a gate is formed at a lower end of the insulating block within a height range corresponding to the cavity.

The injection mold structure and the injection molding method using the same according to the embodiments of the present invention can reduce the height of the gate generated during injection by improving the structure of the upper mold and the nozzle, and significantly reduce material loss. Nevertheless, the injection mold structure and the injection molding method using the same according to the embodiments of the present invention effectively reduce heat transfer to the resin through the improvement of the structure of the nozzle and the flow path, the insulation block and the insulation column at the bottom of the nozzle, and the like, The fluidity of the resin can be maintained.

1 shows an O-ring and a gate shape generated when the O-ring is ejected.
2 is a schematic diagram showing an injection mold structure according to a first embodiment of the present invention.
3 is an enlarged view of an enlarged portion A of FIG. 2.
FIG. 4 is a schematic diagram comparing a gate according to the injection mold structure of FIG. 2 with a conventional one.
5 is a schematic diagram showing an injection mold structure according to a second embodiment of the present invention.
6 is an enlarged view of an enlarged portion B of FIG. 5.
7 is a modified example of the thermal insulation column shown in FIG. 6.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be noted that the following embodiments are provided to aid understanding of the present invention, and the scope of the present invention is not limited to the following embodiments. The following embodiments are provided to more completely describe the present invention to a person with average knowledge in the relevant technical field, and detailed descriptions of known configurations that are determined to unnecessarily obscure the technical subject matter of the present invention are provided. I will omit it.

2 is a schematic diagram showing an injection mold structure according to a first embodiment of the present invention, and FIG. 3 is an enlarged view of part A of FIG. 2.

2 and 3, the injection mold structure 100 of the present embodiment may include an upper mold 110 and a lower mold 120 for molding an injection product P.

The injection product P may typically include an O-ring, but the application object is not particularly limited as long as it has a shape corresponding to and can be applied to the present embodiment. The resin used to manufacture the injection product P may be a thermoplastic resin or a thermosetting resin. In any case, heat insulation may be required between the cavity and the flow path in which the injection product P is molded, and it will be said that the application of this embodiment is possible. However, for convenience, in the present embodiment, it is assumed that the injection product P is an O-ring formed of a thermosetting resin.

The upper mold 110 and the lower mold 120 may form a cavity in which the injection product P is molded. The resin is supplied to the cavity through a predetermined flow path to form the injection product P. This is the same as or similar to the prior art, so a more detailed description will be omitted.

The upper mold 110 may include a nozzle arrangement space 111. The nozzle arrangement space 111 may extend a predetermined depth downward from the upper surface of the upper mold 110 to provide a space for mounting or arranging the nozzle 150 to be described later. In this embodiment, only one nozzle 150 and nozzle arrangement space 111 are shown for convenience, but a plurality of nozzles 150 and/or nozzle arrangement space 111 may be provided as needed, It is not limited to bars.

Meanwhile, the injection mold structure 100 of the present embodiment may include a heat insulating layer 130.

The insulating layer 130 may be disposed on the upper surface of the upper mold 110. The insulation layer 130 is for insulation between the upper mold 110 and the upper structure 140 disposed thereon, and may have a predetermined thickness and may be extended to cover the upper surface of the upper mold 110. In addition, a hole (not shown) may be provided at one side of the heat insulating layer 130 corresponding to the nozzle arrangement space 111 described above for the arrangement of the nozzle 150.

The insulating layer 130 may be any one capable of providing a predetermined insulating function between the upper mold 110 and the upper structure 140, and the material thereof is not particularly limited. However, preferably, the insulating layer 130 may be made of a composite insulating material containing a mixture of glass fiber and a borate-based binder. In addition, preferably, the heat insulation layer 130 is at least one of a heat resistance temperature of 200 to 250°C, a compressive strength (based on 200 degrees) of 250 to 300N/mm², a bending strength (at room temperature) of 500 to 600N/mm², and a thermal conductivity of 0.25 to 0.35 W/mK It may be formed to satisfy the above conditions.

Meanwhile, the injection mold structure 100 of the present embodiment may include an upper structure 140.

The upper structure 140 is disposed on the upper surface of the insulating layer 130, and may be insulated from the upper mold 110 on the lower side through the insulating layer 130. When the injection product P is made of a thermosetting resin, the upper structure 140 on the upper side may be formed in a relatively low temperature area, and the upper mold 110 on the lower side may be formed in a relatively high temperature area with the insulating layer 130 interposed therebetween.

Meanwhile, the injection mold structure 100 of the present embodiment may include a nozzle 150.

The nozzle 150 may be mounted on the upper structure 140 and extend to the nozzle arrangement space 111 provided in the upper mold 110 past the heat insulating layer 130. An insulating block 160 to be described later may be provided at the bottom of the nozzle 150.

The nozzle 150 provides a resin injection path for molding the injection product P, and flow paths 151 and 152 may be formed therein for this purpose. Here, the flow paths 151 and 152 may extend vertically inside the nozzle 150, and may be divided into a first flow path 151 disposed at an upper side and a second flow channel 152 disposed at a lower side. . The first and second passages 151 and 152 may be vertically communicated to form one passage 151 and 152.

The first flow path 151 may be formed in a shape in which the cross-sectional area of the flow path gradually decreases from the injection hole at the top to the bottom. This allows the resin to flow smoothly downwards by pressure. The lower end of the first flow path 151 may be disposed to correspond to the position of the insulating layer 130 in general. In other words, the first flow path 151 may be formed extending from the upper structure 140 to a portion corresponding to the position of the heat insulating layer 130.

The second passage 152 may be formed to extend vertically from the lower end of the first passage 151 to the lower end of the nozzle 150. The second passage 152 may have a passage cross-sectional area corresponding to the lower end of the first passage 151 and extend to the lower end with a constant passage cross-sectional area. This is in contrast to the fact that the cross-sectional area of the flow path becomes smaller as the first flow path 151 goes downward. The shape of the second flow path 152 is such that a sufficient distance (thickness) between the second flow path 152 and the outer surface of the nozzle 150 is secured from the lower side of the heat insulating layer 130, so that the inside of the second flow path 152 Helps reduce heat transfer.

Preferably, for a sufficient heat shielding effect, the diameter of the flow path of the second flow path 152 may be 30 to 40% of the diameter of the flow path at the top of the first flow path 151. Alternatively, the flow path diameter of the second flow path 152 may be formed to be 15 to 25% of the outer diameter of the nozzle 150.

The second flow path 152 may be formed to extend below the heat insulating layer 130 through the nozzle arrangement space 111. Alternatively, the nozzle 150 may be formed to extend through the heat insulating layer 130 to the nozzle arrangement space 111 corresponding to the upper mold 110 region. As the nozzle 150 or the second flow path 152 is formed extending downward as described above, the height of the gate G decreases, and material loss due to the gate G can be reduced. Preferably, the nozzle 150 or the second passage 152 may be formed to extend downward to a position lower than 50% of the thickness of the upper mold 110 by a predetermined level.

The nozzle 150 may have a predetermined gap 153 and may be spaced apart from the upper mold 110 in the nozzle arrangement space 111. That is, the nozzle arrangement space 111 is formed to have a diameter larger than the outer diameter of the nozzle 150 by a predetermined degree, so that the outer wall of the nozzle 150 and the inner wall of the nozzle arrangement space 111 are spaced apart with a predetermined gap 153. I can. The gap 153 may partially assist in heat shielding from the upper mold 110 to the second flow path 152.

In addition, the injection mold structure 100 of the present embodiment may include an insulating block 160.

The insulating block 160 is provided at the bottom of the nozzle 150 to insulate between the upper nozzle 150 and the lower gate G. Accordingly, the resin in the upper region of the insulating block 160 may have fluidity in a low temperature state, and the resin in the lower region of the insulating block 160 may form the gate G.

The insulation block 160 may include a third flow path 161. The third passage 161 may extend vertically from the top surface of the insulating block 160 to the bottom surface, and may be connected to the second passage 152 described above. The flow path diameter of the third flow path 161 may be formed to correspond to the flow path diameter of the second flow path 152.

The insulation block 160 has an outer diameter corresponding to the diameter of the nozzle arrangement space 111 and may be disposed at the bottom of the nozzle arrangement space 111. As described above, the nozzle 150 has an inner wall of the nozzle arrangement space 111 and a predetermined gap 153, and the lower end of the gap 153 may be sealed by the heat insulating block 160.

If necessary, the insulation block 160 may be mounted and supported at the bottom of the nozzle 150 in a replaceable structure. In this case, after using for a predetermined period of time, the insulation block 160 may be appropriately replaced to maintain insulation performance between the gate G and the flow paths 151 and 152.

The insulating block 160 is not particularly limited, as long as it can provide a predetermined insulating function, and the material thereof. For example, in some cases, the insulating block 160 may include a material similar to the insulating layer 130 described above. However, since the insulating block 160 is disposed closer to the gate G, it may be formed of a material, structure, etc. having better insulating performance than the insulating layer 130. Preferably, the heat insulation block 160 has a heat resistance temperature of 222 to 270°C, compressive strength (based on 200°C) 150 to 250N/mm², bending strength (at room temperature) 150 to 250N/mm², and thermal conductivity of at least 0.10 to 0.15W/mK It may be formed to satisfy one or more conditions.

FIG. 4 is a schematic diagram comparing a gate according to the injection mold structure of FIG. 2 with a conventional one. 4A shows a gate according to a conventional method, and FIG. 4B shows a gate according to the present embodiment.

3 and 4, in the injection mold structure 100 of the present embodiment, the supplied resin forms a gate G through the first to third passages 151, 152, and 161, and is supplied to each cavity. . As illustrated, the regions of the upper structure 140 and the first passage 151 are generally intended as low temperature regions, and the upper mold 110 region with the heat insulating layer 130 interposed therebetween is generally intended as a high temperature region.

Here, the resin of the second passage 152 is disposed in the upper mold 110 which is a high temperature region, but the wall thickness of the nozzle 150 according to the diameter of the passage of the second passage 152, the gap 153 with the upper mold 110 , Heat transfer is reduced by the heat insulating block 160 at the bottom, and thus may exist in a state with fluidity. Therefore, the gate G is from the lower end of the insulating block 160 to the cavity between the upper and lower molds 110 and 120, and the height thereof can be minimized, and thus, loss of material can be significantly reduced.

5 is a schematic view showing an injection mold structure according to a second embodiment of the present invention, and FIG. 6 is an enlarged view of part B of FIG. 5.

5 and 6, the injection mold structure 200 of this embodiment may include an upper mold 210, a lower mold 220, an upper structure 240, and an insulating block 260, which is It may be formed in the same or similar to the corresponding configuration.

Meanwhile, the injection mold structure 200 of the present embodiment may include a nozzle 250.

The nozzle 250 corresponds to the nozzle 150 of the above-described embodiment. However, in the nozzle 250 of the present embodiment, an insulating column 254 may be provided in a predetermined area at the lower end.

The thermal insulation column 254 is formed to extend a predetermined height from the lower end of the nozzle 250 and may be inserted into the nozzle 250. Inside the heat insulating column 254, a second flow path 252 may be formed to extend vertically. The second passage 252 inside the thermal insulation column 254 extends from the first passage 251 on the upper side, and is similar to the second passage 152 of the above-described embodiment. The thermal insulation column 254 is to further improve the thermal insulation performance of the second flow path 252, and may preferably extend vertically from the bottom of the thermal insulation layer 230 to the bottom of the nozzle 250.

The insulating column 254 may be made of a material different from that of the nozzle 250. However, the thermal insulation column 254 is not particularly limited as long as it can provide a predetermined thermal insulation function, and the material thereof. For example, the insulating column 254 may be formed of a material similar to the insulating layer 130 or the insulating block 160 of the above-described embodiment.

However, since the heat insulating column 254 receives a relatively large compressive force compared to the heat insulating layer 230 and the like, it may be formed of a material or structure having superior compressive strength. Preferably, the heat insulating column 254 may be made of a composite insulating material in which inorganic raw materials, high strength fibers, organic binders, fillers, etc. are mixed, heat resistance temperature 250~300℃, compressive strength (200 degrees) 450~550N/mm², The bending strength (based on room temperature) may be formed to satisfy at least one condition of 450 to 550N/mm² and a thermal conductivity of 0.20 to 0.30W/mK.

Meanwhile, since the operation and effect of this embodiment are similar to those of the above-described embodiment, detailed descriptions are omitted.

7 is a modified example of the thermal insulation column shown in FIG. 6.

Referring to FIG. 7, the thermal insulation column 354 according to the present modification may include a plurality of columns 354a to 354c disposed concentrically around the second flow path 352. As illustrated, the plurality of columns 354a to 354c are composed of first to third columns 354a to 354c. However, the number of columns 354a to 354c may be increased or decreased as needed, and is not necessarily limited to the illustrated example.

The first column 354a may be provided with a second flow path 352 in the center, and the second column 354b may be formed to extend vertically while accommodating the first column 354a. Similarly, the third column 354c accommodates the second column 354b therein and may be formed to extend vertically. As illustrated, the first to third columns 354a to 354c are shown as substantially cylindrical structures, but may be formed as polygonal structures or asymmetrical structures as necessary.

Preferably, predetermined air gaps 355a and 355b may be provided between the columns 354a to 354c. This is to further improve the insulation effect. Specifically, the outer circumferential surface of the first column 354a and the inner circumferential surface of the second column 354b may be spaced apart by a predetermined distance to provide a first air gap 355a, and the outer circumferential surface and the third column of the second column 354b The inner circumferential surface of the 354c may be spaced apart by a predetermined interval to provide a second air gap 355b. The interval between the air gaps 355a and 355b is not particularly limited, but may preferably be formed to be 10 to 30% of the thickness of each column 354a to 354c.

In addition, a plurality of radially extending ribs 356a and 356b are provided in each of the air gaps 355a and 355b to support each of the columns 354a to 354c. That is, a plurality of first ribs 356a are extended and formed between the first column 354a and the second column 354b to support the first and second columns 356a and 356b, and the second column ( A plurality of second ribs 356b are formed to extend between 354b and the third column 354c to support between the second and third columns 356b and 356c. These plurality of ribs (356a, 356b) also function as a means for supporting the longitudinal load applied to the heat insulating column 354, despite the formation of the air gap (355a, 355b), the deformation of the heat insulating column 354 Can be prevented.

In addition, the thermal insulation column 354 may include a plurality of floors 357a to 357c spaced apart from each other in the longitudinal direction along the second flow path 352. In the case of this embodiment, the first to third followers 357a to 357c are illustrated. Each floor (357a to 357c) may be formed in a plate shape in which a second passage (352) is disposed in the center, and extends between each column (354a to 354c) to support each column (354a to 354c). It can also have functions.

As described above, the injection mold structures 100 and 200 according to the embodiments of the present invention improve the structures of the upper molds 110 and 210 and the nozzles 150 and 250 to increase the height of the gate G generated during injection. Reduction, and the resulting material loss can be significantly reduced. Nevertheless, the injection mold structures 100 and 200 according to the embodiments of the present invention have improved the structure of the nozzles 150 and 250 and the flow paths 151 and 152; 251 and 252, and at the bottom of the nozzles 150 and 250 Through the heat insulating blocks 160 and 260 and the heat insulating column 254, it is possible to effectively reduce heat transfer to the resin and maintain fluidity of the resin.

In the above, embodiments of the present invention have been described, but those of ordinary skill in the art will add, change, delete or add components within the scope not departing from the spirit of the present invention described in the claims. Various modifications and changes can be made to the present invention by means of the like, and it will be said that this is also included within the scope of the present invention.

100, 200: injection mold structure 110, 210: upper mold
120, 220: lower type 130, 230: insulation layer
140, 240: superstructure 150, 250: nozzle
160, 260: insulation block P: injection
G: gate

Claims (7)

avoirdupois;
A lower mold forming a cavity in which an injection product is molded between the upper mold;
A heat insulating layer disposed on the upper part of the upper mold;
An upper structure disposed on the heat insulating layer;
A nozzle extending downward from the upper structure and supplying a resin for molding the injection product into the cavity; And
Including; a heat insulating block disposed at the bottom of the nozzle,
The upper mold has a nozzle arrangement space extending a predetermined depth downward to the upper surface,
The nozzle is extended below the heat insulating layer and disposed in the nozzle arrangement space, and is spaced apart from the upper mold in the nozzle arrangement space with a predetermined gap,
The heat insulating block, having an outer diameter corresponding to the diameter of the nozzle arrangement space, is disposed at the bottom of the nozzle arrangement space is formed to shield the lower end of the gap,
The nozzle,
A first flow path extending downward from the top; And
And a second passage extending downward from the lower end of the first passage,
The first flow passage is formed in a tapered shape in which the flow passage cross-sectional area becomes smaller as it goes downward,
The second passage, the injection mold structure extending downwardly with a passage cross-sectional area corresponding to the lower end of the first passage. delete The method according to claim 1,
The second flow path, the injection mold structure, the upper end is formed extending from a point corresponding to the position where the heat insulating layer is disposed. The method according to claim 1,
The nozzle arrangement space is formed extending downward to a position lower by a predetermined level than a point of 50% of the upper mold thickness,
The second flow path, the injection mold structure is formed in a flow path diameter of 15 to 25% of the outer diameter of the nozzle. The method according to claim 1,
The nozzle has an insulating column therein,
The heat insulating column is formed to extend a predetermined height from a point corresponding to the bottom surface of the heat insulating layer to the lower end of the nozzle, is inserted into the nozzle and disposed, the second flow path is formed to extend vertically,
The heat insulating layer is formed with a thermal conductivity of 0.25 to 0.35 W/mK,
The insulating block is formed with a thermal conductivity of 0.10 to 0.15W/mK,
The insulating column is formed with a compressive strength (based on 200 degrees) 450-550N/mm², an injection mold structure. The method of claim 5,
The insulating column,
A first column provided with the second flow path and extending vertically;
A second column accommodating the first column and extending vertically;
A first air gap formed between the first and second columns with the first and second columns spaced apart by a predetermined distance;
A plurality of first ribs extending radially between the first and second columns; And
Containing, injection mold structure; a plurality of floors spaced apart vertically along the second flow path. An injection molding method for molding an injection product using the injection mold structure of claim 1, and forming a gate within a height range corresponding to the cavity at the lower end of the insulating block.

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