KR910005160B1 - Manufacture of resin manifold - Google Patents

Abstract

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Description

Manufacturing method of resin product having bent hollow part and core which can be used in this method

1A and 1B show a configuration example of a flexible metal tube as a core material having high flexibility and shape preservation.

2A and 2B show a configuration example of a flexible metal tube having only high flexibility. A partial enlarged view shows the top of each figure.

3 and 4 show schematic examples showing the configuration of the core.

FIG. 5 is a cross-sectional view showing a working state used to coat an elastomer on the surface of a flexible tube having the configuration shown in FIG. 2A in manufacturing a core using the flexible tube.

6 and 7a show examples of the core composed of the combination of the flexible tube, the low melting point alloy and the flexible heater shown in FIG. 2, and FIG. 7b shows a partially enlarged view of the configuration of the core shown in FIG. ,

8 shows an example of a flexible heater constituting the above-described skeleton structure.

9 shows a modification of the configuration of the core shown in FIG.

FIG. 10 shows an example of a terminal metal part when the flexible tube described above is coated with an elastomer in a bent state.

11 shows an example of a flanged S-tube made of the resin of the present invention.

12 and 13 show parts and accessories for securing the core in the mold.

14a to 14d and 15 schematically show an example of a forming step and a method of removing the core when using the core of the present invention.

16 and 17 show a combination of cores and a combination of components for connecting a plurality of cores and cores to each other when manufacturing a bifurcation pipe and a manifold.

The present invention relates to a method for producing a resin product having a curved hollow portion and a core used in the method. Specific examples of applications of these methods and cores include the use of water inlets and outlets, pipes such as oil strainers, conduits and suction pipes of automotive parts with flexural hollows, for example when metallic materials of automobile parts are replaced with resins. It is used for a manufacturing method.

For example, as a method for producing a resin product having a curved hollow portion such as an S-tube or a U-tube that cannot be easily obtained by molding using a slide core, it is possible to pre-inject Zn, Sn, Sb, etc. A formed low melting point alloy (e.g., melting point of 138 DEG C) is formed, the formed product is inserted into the mold as a core, the core is covered with a resin, and the core composed of the low melting point alloy is heated to melt away from the formed product. There is a method of obtaining a resin product having a curved hollow part by letting it go out.

However, removing the core composed of the low melting point alloy by application requires a long-term heating process to melt it, and furthermore, in the case of mass production, recovery and reinjection of the molten low melting point alloy is inevitable. Therefore, the above method has a disadvantage in that the productivity is very low, and heat deterioration of the resin is likely to occur because a long time heating step at an undesirably high temperature is inevitable for the resin product.

The present invention relates to a method for producing a resin product having a curved hollow portion, characterized by using a core having a high flexibility, high shape preservation and an elastomeric coated surface. The present invention can be easily produced by the simple method of detaching the core from the molded article, and the core can be reused.

That is, the first aspect of the present invention relates to a method for producing a resin product having a bending hollow portion. The second aspect relates to the core used in the production method thereof.

Details of the first and second aspects will be described below.

The present invention can be widely used even when the resin product having the curved hollow portion is a two-branch pipe or a multi-pipe. In this case, a bifurcation pipe or manifold having a complicated shape can be easily manufactured by combining a plurality of cores and, if necessary, insert cores (hereinafter abbreviated as dies) or branch parts.

As a first example, a core obtained by coating a heat resistant elastomer in a framework having high flexibility and shape preservation is deformed into a desired shape, the modified core is inserted into a mold, and the resin is packed in a cavity of the mold, The manufacturing method of the resin product which has a bending hollow part characterized by removing a core from the produced molded article, and the core used for this manufacturing method are mentioned.

As a second example, a method for producing a resin product having a curved hollow portion according to the first example, using a core obtained by sealing a low melting point alloy in a highly flexible skeleton structure to impart high shape retention to the skeleton structure, and The core used for this manufacturing method is mentioned.

As a preferred example of the first example, the use of a core configured to obtain an accurate molded article by coating the elastomer in a framework having high flexibility and shape preservation, which has been preformed into the desired shape to have the same outer diameter in each part of the core, is achieved. The manufacturing method of the resin product which has the bending hollow part which concerns on the 1st example, and the core used for this manufacturing method are mentioned.

In manufacturing the manifold, the core for the manifold is formed by appropriately selecting and blending the core used in the above example in consideration of the position, shape, and the like to be used. If necessary, use hard insert dies and / or branching parts for connection.

As examples under these conditions, the following are mentioned.

Firstly, a plurality of cores with high flexibility and shape preservation used in the above example are connected to each other by branching parts to obtain a forming core, and after the core is deformed into a desired shape, the core is inserted into a mold and The method of manufacturing a hollow manifold made of resin, characterized in that the resin is packed in a mold cavity, and then a plurality of cores are removed from the resulting molded article.

Secondly, a plurality of cores used in the above examples with high flexibility and shape preservation are connected to the rigid insertion cores to form a wide hollow portion through the curved hollow portion, and to form a plurality of cores for forming the curved tube portion. After deforming to obtain a molding core, the core is inserted into a mold, the resin is packed in a mold cavity, and then a plurality of cores having a high flexibility and form integrity from the resulting molded article and the forming core are formed. It is a method of manufacturing a multi-resin tube consisting of a plurality of bent hollow portion and a wide hollow portion through the bent hollow portion, characterized in that the hard insertion core is removed.

In addition, the above examples can be used for foam molding, and in this case, the resin is provided in a method for producing a resin product having a bending hollow portion according to various examples above, obtained by foam molding.

The present invention relates to a method for producing a resin product having a curved hollow portion, such as S-tube or U-tube. More specifically, molding while maintaining the core in the desired shape because of its high form preservation in which the core is not substantially deformed by the flow of resin during molding and the high flexibility that the core deforms depending on the shape of the molded part when the core is removed. The present invention relates to a method for producing a resin product having a bent hollow portion, comprising the steps of molding a resin product and removing the core by adding a resin to at least the periphery of the core which does not damage the resin product.

In the present invention, "applying a resin to at least the periphery of the core" means that the present invention is a part by forming a molded part having a curved hollow part when producing a resin product having a molded part and a molded part having no curved hollow part. Means to apply. As the application method, injection molding or injection molding is commonly used, but the resin can be added by a method suitable for molding a desired resin product such as coating.

The above-described core of the present invention has a high flexibility and a preservation property, and has a high flexibility skeleton structure, preferably a hollow structure, an elastomer covering the surface of the structure and, if necessary, a high shape preservation provided in the hollow portion of the structure. It consists of means to have.

The cores having high flexibility and shape preservation used in the present invention preferably have high flexibility and cores at least so high that their flex or non-bending force can deform the core with a force below the compressive strength of the resin matrix of the product. It is a core having a shape preservation high enough not to be deformed by a flow pressure (2 to 3 kg / cm 2). More preferably, when removing the core, its flex or specific flexural force is 50 kg or less, the surface of the core is covered with an elastomer that does not adhere to the resin used, and flows at the molding and processing temperatures of the resin. It is not heat-resistant, and the surface roughness can be avoided.

The skeletal structure composed of the aforementioned cores having a high form integrity and high flexibility in which the core is not deformed by the flow pressure of the resin is a high flexibility and a cylindrical shape, for example.

Specific examples of the skeletal structure include a tubular metal structure made of, for example, copper, copper alloy, lead, aluminum, aluminum alloy, etc .: skeletal structure having the structure shown in FIG. 1. Steel foil, copper, copper alloy, aluminum alloy Flexible tubes such as blowers obtained by forming tubes from the back and the like; and combinations of the tubular structures and the flexible tubes.

An example of a flexible tube is a flexible tube having a configuration such as that used in a protective tube for an optical fiber, a vibration part of a desk or a floor lamp, and the like. In order to maintain the desired skeletal structure with the configuration shown in FIG. 2, a low melting point alloy is sealed in the hollow portion of the flexible tube or hose to enhance shape integrity, and the tube or hose is heated to melt the low melting point metal. By providing flexibility, the tube or hose can be molded into a desired shape, and the shape integrity can be improved by cooling the tube or hose. Although the shape of the framework is usually cylindrical, its cross section may be oval or square, depending on the shape of the desired product.

In this case, as the heating method, various methods such as an external device such as heating by heat transfer by hot air and a method using radiant vibration induction heating and a method of providing a heater inside the core can be used. have.

However, in the present invention, the structure of the skeleton structure and the materials constituting the structure are not limited as long as the structure has high flexibility and, if necessary, high form retention.

The elastomer provided on the surface of the framework shown in FIG. 1 or 2 can avoid the roughness of the surface of the framework and there is no limitation as long as it does not adhere to the resin unless it flows at the molding temperature of the resin to be molded.

Specific examples of elastomers that can be used in the present invention include synthetic rubbers and thermoplastic elastomers such as natural rubber, silicone rubber, fluoro rubber, urethane rubber, butadiene rubber and the like.

As a method of providing the elastomer to the skeleton structure shown in FIG. 1 or 2, a molding method such as injection, injection, compression molding or the like can be used.

Specifically, a straight metal rod fixing the inner diameter of the skeletal structure is inserted into the skeletal structure, the position of the skeletal structure is fixed to the mold, and then the skeletal structure is inserted into the mold for rubber coating, and the elastomer is injected by vacuum or the like. To provide.

After inserting the metal rod bent in the desired shape into the skeleton structure to fix the metal rod, insert the skeleton structure into the mold for rubber coating, and coat the skeleton structure with the elastomer to provide the elastomer in the desired shape from the beginning. can do.

However, when the radius of curvature is less than 80 mm at the bend of the resin to be produced by using a core consisting of a flexible tube and an elastomer (for example, a heat shrinkable silicone tube), first the tube is covered with an elastomeric tubing, and the elastomer tube By providing a sheath, a depression of the flexible tube occurs in only a small portion of the tube, and the flexibility of the core can be maintained since this depression is not filled by the sheath with the elastomer. The two elastomers are preferably very adherent to each other, and are preferably of the same kind.

The thickness of the provided elastomer is not limited as long as the surface roughness of the framework can be avoided.

Specific manufacturing method of the core is as follows. A method of manufacturing a core, which is the second aspect of the present invention, will be described in more detail with reference to FIGS. 3 to 10.

As shown in FIGS. 3 and 4, during molding, the metal terminal portion 1 and the metal terminal portion 2 having portions for holding and positioning in the mold and holding portions in the mold by means of pins or the like. ) Is attached to one end and the other end of the flexible pipe by means of welding or bolt nut to the skeleton structure 3 (flexible pipe) shown in FIG. 1 or 2. Then, the metal rod 6 having the inner diameter of the skeletal structure having the metal terminal portions 1 and 2 attached to the skeletal structure is inserted into the skeletal structure and fixed by bolt means, for example.

The surface of the skeleton structure 3 is covered with a heat shrinkable tube made of silicon (thickness: 0.5 to 1 mm), and the tube is applied by applying heat to the surface of the skeleton structure 3. Then, as shown in FIG. 5, it is inserted into a cylindrical mold 8 for vacuum injection, and the mold cavity is evacuated by means of a vacuum pump 9 means. Thus, after the silicone rubber 5 of the same type as the tube 4 covering the structure (skeletal structure) is inserted and compressed, its surface is smoothed and its dimensions are adjusted to the product diameter. The structure is thus covered with silicone rubber 5 and then heated to exert heat. In this case, if necessary, the adapter 7 may be used to coat the silicone rubber 5. In this process, the adapter will be used to position in the mold 8.

Next, the metal rod inserted into the framework 3 covered with silicone rubber is pulled out of the auxiliary structure. As shown in FIG. 6 and FIG. 7, the heater 10 having a high flexibility such as a frame is inserted into the cavity of the structure. Thereafter, the low melting point alloy 11 is sealed in the space between the inner surface of the skeletal structure 3 and the outer surface of the flexible heater 10 to obtain a desired core. The melting point of the alloy sealed therein should be in the range of about 50 ° C. and the upper limit of about 140 ° C. In addition, an alloy can be selected freely according to the application method, such as a kind of resin and resin.

Of course, the metal terminal portion 2 should be molded so that problems do not occur when the core is pulled out of the molded product. As the skeletal structure 3, when one having the structure shown in FIG. 1 is used, even if the flexible heater 10 and not the low melting point alloy 11 is inserted into the cavity of the structure, it functions sufficiently as a core. Can be exercised.

The aforementioned high flexibility heater is sufficient to have a capacity capable of generating sufficient heat capacity to melt the low melting point alloy 11 enclosed in the core. In particular, the heater is as follows. Specific examples of the heater structure will be described below with reference to FIG.

As the skeleton structure 18 of the heater, one having the same structure as that of the skeleton structure used in the above-described core is used. The metal terminal portions 1 and 2 and the fixing metal terminals 12 and 13 shown in FIGS. 3 and 4 are attached to the structure by welding.

Next, the structural surface is coated with an insulating layer 14 (heat-shrinkable silicon tube, etc.), and then the grass-nitron wire 15 is wound on the structure as appropriate, for example at intervals of about 5 mm. In this case, if the wires 16 drawn for the power supply are to be in the same direction, the power supply grass-nitron wires 15 and 16 are wound side by side parallel to each other on the insulating layer 14. As the power supply wire 16, Teflon (Dupont registered trademark) coated with a line having high heat resistance is preferably used in consideration of the surface temperature of the grass-nichrome wire.

Finally, the treated skeletal surface completes the flexible heater by applying an elastomer (silicone rubber) 17 at which the low melting point alloy to be used does not flow at least at the melting point.

The cavity of the heater pipe 18, which is not very flexible, can be used as a cooling space for core cooling to harden the alloy inside the core.

The elastomer supply is carried out in the same manner as for supplying the core to the skeletal structure surface shown in FIG.

Of course, as shown in FIG. 9, the so-nichrome wire 15 is applied to the core itself in the same manner as described above.

Preferably, the frame structure 19 having the same structure as that described above is inserted into the center portion of the core, and the cavity of the internal flexible pipe 19 has a cooling space for reducing the amount of the low melting point alloy 11. It can be used to reduce the solidification time. The framework 19 of the core needs to coat its surface with, for example, an elastomer to prevent air leakage.

Of course, the material constituting the heater and the structure of the heater are not important matters as long as the requirements of the present invention are satisfied.

In the case of the heater having the structure as in the above specific example, when the elastomer is first coated on the predetermined shape, in consideration of the radius of curvature bent in the predetermined shape in advance, the metal terminal part 21 should be designed. Thus, as shown in FIG. 10, the metal rods can be inserted and withdrawn into the framework 3. In this case, separate split molds should be used.

As the resin used in the process for producing a molded product having the bent cavity of the present invention, any of thermoplastic resins or thermosetting resins can be used as long as these resin products satisfy certain specifications. Resin has a predetermined amount of reinforcing agent, filler, foaming agent. A coloring agent, a stabilizer, etc. can be mixed.

When using a thermoplastic resin as a resin for the production of a resin product having a bending hollow part by a core of the present invention comprising a skeleton structure having high flexibility and form preservation and an elastomer coated thereon, such as injection molding, foam injection molding, and the like Method can be used. When using a thermosetting resin, molding methods such as injection molding, injection molding, mobile molding, and compression molding can be used.

As a specific example, a process for making a resin product in two-branch or multi-pipe molding will be described below with reference to FIGS. 16 and 17. First, an example of a bifurcated pipe product is described below.

In the bifurcation engine having the bent hollow portion shown in FIG. 16, the core 100 of the third embodiment is used. The two cores are preformed in the above manner, and then connected to each other by partial means for a branch 101 having a temporarily fitted structure for joining the two cores in the body to obtain a forming core. Then, the molding core thus obtained is inserted into the mold 8B. In this case, when the fixing only to the end of the core has a problem (for example, when the resin 5 is filled, the portion for branching is moved by the flow pressure of the resin). The portion of is formed on the branch portion 101 by forming a projection or the like, and is formed by fixing a hole in the mold 8B at the same position.

Therefore, the resin 5B is filled into the mold 8B by extrusion molding, and the final molded part is then fixed while the flange portion is fixed in the same manner as the method used in the case of the above-mentioned "S" tube. Take out to the product. This yields a resin product in the form of a two branch engine. In this case, the branch remains in the molded product and forms part of the product.

Next, in the case of the manifold-shaped resin product shown in FIG. 17, the magnet 103 is molded into the mold insert core 104 to form a wide part of the cavity from the bent pipe part, as shown in the schematic diagram of the adapter shown in FIG. Install) In order to obtain a core for molding, a plurality of preformed cores 100 are connected to each other by means of the magnet 103. Subsequently, the molding core is inserted into the mold 8C, and the resin 5 is filled into the mold cavity by extrusion molding or the like. Then, the final molded product 106 is taken out and the molding insert die 104 is pulled out. Thereafter, the core 100 is pulled out to obtain a manifold resin product.

The resin product having the bending hollow part according to the present invention is to transform a core having high flexibility and good shape preservation (retention) into a desired shape, inserting the modified core into a mold, and filling the resin with a mold cavity. It can be obtained by extracting the core from the molded product.

In order to obtain a bifurcated or manifold resin product, a plurality of cores of the present invention are assembled into a body by means of a branch or a part used as a forming core.

One example of a core configuration for producing a two-branch molded product is a core structure made by assembling a branch (core-connection) with the core of the present invention.

Here, the term "branch part" means a part obtained by assembling, fixing and bonding them together, welding, etc. previously integrally molded or at least two parts. The structure of the branch and the material used therein are not critical as long as the branch can hold a plurality of cores even by extrusion, insertion, or the like. As materials that can be used, for example, resins, metals, and ceramics can be used.

In the case of making a core for a manifold having a complicated shape, the plurality of cores of the present invention are connected to a rigid mold insert die, core or the like for assembling them in a body. The core thus obtained can be used as a casting core.

Hereinafter, with reference to FIGS. 12, 13, 14, and 15, a pipe having a pipe shape having a flange shown in FIG. 11 will be described as a specific example.

For example, in the case of the cores of the first and second embodiments, the core is pushed into the mold to be molded in advance so as to be molded in advance during bending (during bending). In this case, a metal terminal 2 of the core 53 is provided with an adapter 54 having a pinhole or the like and a mold 55 for molding (provisionally) to be placed in the mold, for inserting molding, injection, or the like. To the side. As a method of connecting the adapter 54 to the core, a method of attaching the core to the adapter by a magnetic force means of the magnet, a method of fixing by means of bolts or the like, a method of driving the magnet 56 or the like into the adapter 54, Either may be.

Then, the provisionally shaped core having the adapter 54 attached is inserted into the pin protrusion of the mold 8A while keeping its mold in place. Then, the resin 5A is filled into the cavity part of the mold 8A by extrusion molding or the like. In this case, it is preferable to fill the resin 5A into the mold 8A from the metal terminal portion 1 where possible, since it prevents the generation of bending force.

After the resin is filled into the mold 8A, the core 53 in the final molded product is immediately removed from the molded product in the mold. This is also done by squeezing the core together with the molded product from the mold, for example by fastening or holding or elevating the metal terminal portion 1 by means such as fastener 60 or by means of oil pressure. It is also possible to fix the flange portion of the product 5B on the fixing portion 59, and to pull out the core 53 from the molded product 58. In this case the adapter used for positioning in the mold is separated from the core 53 and left at the end of the molded product 5B or in the mold 8A.

The extracted core and the adapter 54 separated from the core are recombined and tentatively molded by caustic molding means, and molding is performed in the same manner as the above-described method.

In the case of the core of the third embodiment, the heater in the core transfers high flexibility to the core by primarily applying heat to deceive the low melting point alloy inside the core, and is caustic during bending (bending) with the core and adapter 54. It is pushed into the predetermined position of the mold 8 '. Next, the low melting point alloy inside the core is hardened, that is, for example, the caustic mold 8 is hardened by air cooling or by air introduction at a cooling cavity speed into the core. Then, the core is inserted into the mold 8A, and the resin 5 is filled at the mold cavity speed by extrusion molding, injection, or the like. Subsequently, the heater in the core is heated again to remove the core in the same manner as described above. Then, the above process is repeated to obtain a molded product 51. The design of the metal terminal part 1 having the connection part, the adapter 54 and the fastener 60 used in the present invention is not so important as long as it is possible to extract the core from the molded product and place the core in the mold. .

The invention is illustrated by the following examples which do not limit the scope of the invention.

Example 1

In order to form the hollow part of the flange S-pipe (length: 200 m, outer diameter: Φ 34 mm, bending radius: 50 mm, flange diameter: Φ 60 mm) shown in FIG. 11, the core is manufactured as follows. A metal flexible tube (external diameter Φ 19 mm, internal diameter Φ 16 mm) having the configuration shown in FIG. 1a is covered with a heat shrinkable silicone tube (thickness 1 mm, internal diameter Φ 30 mm), and heated to 150 ° C. or more for 10 minutes to form a silicone By shrinking the tube, the silicone tube is attached to the surface of the flexible tube. The silicone rubber is then coated in a flexible tube to a thickness of 1.5 mm by injection under vacuum as an elastomer and cured at about 150 ° C.

1300G, 아사히가세이고오교 가부시끼가이샤 제품)으로 피복시킨다. 성형후, 주형의 성형품으로부터 코어를 제거한다. 코어는 약 100kg의 힘으로 제거될 수 있으며, 그러므로 수지로 만들어진 굴곡중공관을 용이하게 수득할 수 있다. 이러한 단계는 제8도에 도식적으로 나타낸다.The cores thus obtained are then deformed to fit the internal space of the S-tube, inserted into the molds, and the surface of the cores is then injected by 33% GRF-reinforced nylon 66 (LEONR).

1300G, Asahi Kasei Kogyo Co., Ltd.). After molding, the core is removed from the molded article of the mold. The core can be removed with a force of about 100 kg, thus easily obtaining a hollow hollow tube made of resin. This step is shown schematically in FIG.

[* 1 Injection molding condition]

Example 2

The metal flexible tube as used in Example 1 was coated with a fluororubber and a heat shrinkable silicone tube as an elastomer in the same manner as in Example 1 to obtain a core. The core is deformed and molded in the same manner as in Example 1. The core is removed from the resulting molded article. The core can be removed with substantially the same removal force as in Example 1. This yields a curved hollow tube made of resin.

Example 3

GA520, 아시히가세이고오교 가부시끼가이샤 제품, 20%의 유리 섬유로 강화), 폴리에틸렌테레프탈레이트(SUNPET

3300G, 아시히가세이고오교 가부시끼가이샤 제품, 30%의 GF로 강화), PPS(신에쓰가가꾸고오교 가부시끼가이샤) 및 폴리카르보네이트(NOVAREX

7025G30, 미쓰비시가가꾸고오교 가부시끼가이샤 제품, 30%의 G로 강화)를 각각 사출성형한다. 코어를 성형제품으로부터 제거한다. 이들 코어의 경우, 제거에 필요한 힘은 수지의 종류에 상관이 없으며, 굴곡중공 수지관이 용이하게 수득될 수 있다.Four types of resins, polyacetals (TENAC), were prepared in the same manner as in Example 1 using the cores used in Examples 1 and 2.

GA520, Ashhi Kasei Kogyo Co., Ltd., reinforced with 20% glass fiber), polyethylene terephthalate (SUNPET

3300G, Ashhi Kasei Kogyo Co., Ltd., reinforced with 30% GF), PPS (Shin-Etsu Chemical Co., Ltd.) and Polycarbonate (NOVAREX)

7025G30, Mitsubishi Chemical Co., Ltd. and Ogyo Co., Ltd., reinforced with 30% of G) are injection molded. The core is removed from the molded article. In the case of these cores, the force required for removal is irrespective of the type of resin, and a flexible hollow resin tube can be easily obtained.

[Injection molding condition of resin]

Example 4

The core is prepared as follows. A flexible tube made of metal (SUS) having the configuration shown in FIG. 2A (waist diameter Φ 19 mm, internal diameter Φ 16 mm) was coated with silicon rubber in the same manner as in Example 1 to coat the outer diameter of the tube with Φ 27 mm. Adjust Then, the flexible heater shown in FIG. 8, having an outer diameter of Φ14 mm and a heater capacity of 60 w / m, is inserted and fixed in a flexible tube coated with silicone rubber, and a low melting point alloy (melting point) is provided between the heater and the flexible tube. : 138 ° C) and sealed to obtain a core (Fig. 7).

Subsequently, the heater inside the core is heated at 150 ° C. to melt the low melting point alloy, and then the core is deformed and cooled in the same manner as in Example 1 to cool the low melting alloy to solidify the core in advance. The core is inserted into the mold and 33% GF-reinforced nylon 66 resin is packed into the mold cavity in the same manner as in Example 1. After peking, the heater was charged with electricity for about three minutes from the beginning of the cooling time to re-melt the low melting alloy in the core and remove the core from the molded part of the mold. The core can be easily removed with a force of 70 kg, and a curved tube made of resin is obtained.

Example 5

Molding is carried out in exactly the same manner as in Example 4 except that the melting point of the low melting point alloy in the core used in Example 4 is changed from 138 ° C to 74 ° C (temperature substantially the same as the forming temperature).

After completing the resin packing in the mold cavity, the core temperature of the core reaches 100 ° C. in the cooling time (60 seconds), and the low melting alloy in the core melts without the need to charge the internal heater with electricity. As a result, the core can be removed from the molded article, and a curved hollow tube made of resin is obtained.

Example 6

Using the core used in Example 5, a composition prepared by incorporating 0.3% of a blowing agent into the resin (30% GF-reinforced nylon 66 resin) was subjected to a structural injection molding (foaming ratio: 5 to 10%) by a short method. )do. The core is removed from the resulting molded article to obtain a curved hollow tube made of resin. In this case, the core can be easily removed with a 30% lower removal force than in Example 5.

Example 7

A metal rod, pre-curved to fit the S-tubular shape, is inserted into a flexible metal tube such as that used in Example 4 serving as a skeletal structure. The metal tube was coated with a heat-shrinkable silicone tube and silicone rubber as an elastomer by vacuum injection as in Example 1 except that a split mold was used. The core thus obtained is inserted into a mold and molded in 33% GF-reinforced nylon 66 resin in exactly the same manner as in Example 1, and then the core is removed from the molded article. By removing the core from the molded article with a force of about 100 kg, a flexible hollow tube made of resin can be easily obtained.

Example 8

14G43, 아사히가세이고오교 가부시끼가이샤 제품)로 미리 만들어진 주형에 자리잡을 수 있는 돌출부 및 스냅 고정 구조를 갖는 수지로 된 분기 부품에 의해 고정시킴으로써 서로 연결시킨다. 코어의 양말단 및 분기용 부품을 주형폐쇄 공정과 동시에 성형을 위한 코어로서 삽입함으로써 고정시킨다. 그후, 성형품으로부터 2개의 코어를 제거하여 굴곡중공부를 갖는 2-분기 수지제품을 수득한다. 이 경우에, 분기용 부품은 성형품에 남아있어 제품의 일부를 구성한다.As shown in FIG. 16, 43% reinforced nylon 66 resin (LEONA) was formed by injection molding into two pieces two cores having the same configuration as that used in Example 7.

14G43, manufactured by Asahi Kasei Kogyo Co., Ltd.), is connected to each other by fixing by a branch part made of resin having a protrusion and a snap fixing structure that can be placed on a mold made in advance. The sock end and the branch part of the core are fixed by inserting as a core for molding simultaneously with the mold closing process. Thereafter, two cores are removed from the molded article to obtain a two-branched resin product having a bending hollow portion. In this case, the branching parts remain in the molded part, forming part of the product.

Example 9

As shown in FIG. 17, four cores having the same configuration as the core used in FIG. 4 are connected to the mold insert die to form a large hollow by magnetic force of a magnet embedded in the mode insert die. To obtain.

After molding in the same manner as in Example 4, four cores were removed one by one. Thereafter, the metal insertion die is removed to obtain a resin product having a curved hollow portion containing a wide hollow portion.

In all the above embodiments, there is no significant change in the thickness of the molded article or a rupture upon removal, and a resin product having a satisfactory curved hollow portion can be obtained. Moreover, repeated use of the core has no practical effect on the quality of the molded article.

Comparative Example 1

(300G), 아사히가세이고오교 가부시끼가이샤 제품, 천연색)를 500kg/㎠의 사출압력으로 주형 동공에 패킹한다. 성형후, 성형품을 주형으로부터 제거하여 150℃의 가열 챔버(공기 오븐)에 넣어 코어를 용융시켜 버린다. 그러나, 코어를 용융시켜 버리는데는 3시간 이상이 걸리며, 성형품의 색이 변화된다. 덧붙여, 저융점 합금이 S-관 성형품의 내부표면에 부착되며, 여기에 이용된 방법의 경우 완전히 제거될 수 없다.The core is injected into a low melting point alloy (melting point of 138 ° C.) in the form of an S tube shown in FIG. 11 to adjust the inner diameter of the hollow portion of the tube to Φ 27 mm. The core is then inserted into a mold for injection molding and 33% GF reinforced nylon 66 resin (LEONA).

(300G), Asahi Kasei Kogyo Co., Ltd., natural color) are packed into the mold pupil at an injection pressure of 500 kg / cm 2. After molding, the molded article is removed from the mold and placed in a heating chamber (air oven) at 150 ° C to melt the core. However, it takes 3 hours or more to melt the core, and the color of the molded article changes. In addition, a low melting alloy is attached to the inner surface of the S-tube molded article, which cannot be completely removed in the method used here.

Comparative Example 2

In order to reduce the discoloration and melting time by the heat of the molded article, it is molded using an alloy having a melting point of 74 ℃ in the same manner as in Comparative Example 1.

However, an unsatisfactory molded article may be obtained because the surface of the core is melted at the resin temperature during resin packing.

Comparative Example 3

In order to form the hollow portion of the flange S-tube shown in FIG. 11, a flexible metal tube (outer diameter? 19 mm, inner diameter? 16 mm) having the configuration shown in FIG. 1 (a) is used as the core. After the flexible tube is deformed into the desired shape and inserted into the mold, injection molding is performed in the same manner as in Comparative Example 1. After molding, efforts were made to remove the core from the molded article, but the resin protruded into the rough portion of the flexible tube and the core was not removed or ruptured.

As is apparent from the above examples, the present invention has the following specific effects.

(1) The core of the present invention obtained by coating the skeleton structure having high flexibility and form retention with an elastomer can be used repeatedly, and a resin product having a bending hollow portion can be easily removed by adding a resin to the core and then removing the core. Can be obtained.

(2) A resin product having a curved hollow portion composed of two branches or a manifold having a complicated branched hollow hollow portion can be easily obtained by using a plurality of cores connected by a branching part or the like.

Claims (15)

Maintains the core in the desired shape with a high form integrity so that the core is not actually deformed by the resin flow during molding and the core is deformed according to the shape of the molded article upon removal of the core and has high flexibility not to damage the resin product, A method of manufacturing a resin product having a curved hollow portion, comprising the step of molding a resin product by removing the resin at least around the core and removing the core after molding. A resin product having a curved hollow portion according to claim 1, wherein the core is composed of a skeleton structure and an elastomer provided thereto, wherein the skeleton structure is at least deformed upon removal of the core and has flexibility not to damage the resin product. Way. The method for producing a resin product having a curved hollow portion according to claim 2, wherein the skeleton structure is a flexible tube made of metal. 3. The resin of claim 2, wherein the core has a flexible tube made of metal, an elastomer provided thereto, a flexible heater provided at the center of the flexible tube, and a low melting point alloy between the flexible tube and the flexible heater. Manufacturing method of the product. The method for producing a resin product having a curved hollow portion according to claim 1, wherein the core is a branched core configured by connecting a plurality of cores to each other through a branching component. The method for producing a resin product having a curved hollow portion according to claim 1, wherein the core is a core obtained by connecting a core for forming a curved tube portion to a hard insertion core for forming a wide hollow portion associated with the curved tube portion. The method for producing a resin product having a bending hollow portion according to any one of claims 1 to 6, wherein the molding is injection molding. The method for producing a resin product according to any one of claims 1 to 6, wherein the molding is injection molding. The method for producing a resin product having a curved hollow portion according to claim 4, wherein a step of removing the core after molding is performed by adjusting the flexible heater to a temperature above the melting point of the low melting point alloy and below the deformation temperature of the resin of the molded article. The bending hollow part of claim 1 having high shape preservation so that the core is not substantially deformed by the resin flow during molding and high flexibility that the core is deformed according to the shape of the molded product and does not damage the molded resin product when the core is removed. Cores for producing resin products. 11. The resin product manufacturing method according to claim 10, wherein the core is composed of a skeleton structure and an elastomer provided thereto, wherein the skeleton structure is at least deformed upon removal of the core and has a high flexibility not to damage the resin product. core. 12. The core for producing a resin product according to claim 11, wherein the skeleton structure is a flexible tube made of metal. 11. The resin article of claim 10, wherein the core is composed of a flexible tube made of metal, an elastomer provided thereto, a flexible heater provided at the center of the flexible tube, and a low melting point alloy between the flexible tube and the flexible heater. Core for the production of The core according to claim 10, which is a branched core obtained by connecting a plurality of cores to each other through a branching component. A core according to claim 10, wherein the core for forming a bend tube portion is made by connecting a hard insertion core to form a wide hollow portion coupled with the bend tube portion.

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