JP2746609B2 - Low melting point alloy core and method of manufacturing the same - Google Patents

Description

The present invention relates to a low melting point alloy core and a method for producing the same,
More particularly, the present invention relates to a low-melting-point alloy core in which a core material is embedded to increase the compressive strength, and a method for manufacturing the same.

[Prior art and problems to be solved]

In general, when molding a final molded product having a hollow portion, a molding material is filled in a state where a core matching the hollow portion is disposed in a molding cavity, and a primary molded product containing a core is molded. There is a method of obtaining a molded article having a hollow portion by removing only the core from the primary molded article.

As the core used for this purpose, there is known a core made of a low melting point alloy that can melt and remove the core by heating to a predetermined temperature after molding a primary molded article containing the core.

However, the core made of the low melting point alloy has a compressive strength at room temperature of 300 to 800 kg / cm ² , depending on its material.
About the melting point temperature, and has the property of decreasing to about 1/3 of the compressive strength at room temperature,
For example, in the case of injection molding, the molding pressure of the molding material at the time of injection molding (usually 800 to 1200 kg / cm ² makes the core easily deformable and does not fulfill the function of the core. There was a problem that a molded product could not be formed.

On the other hand, it is conceivable to increase the compressive strength by adding fibers to the core made of the low melting point alloy, but the wettability between the fibers and the low melting point alloy is poor, and the specific gravity of the low melting point alloy with respect to the fibers is low. Even if it is large, even if it is simply contained, the fiber is separated into the upper layer of the low melting point alloy, and it is difficult to include the fiber in the low melting point alloy.

The present invention solves the above-mentioned problems of the conventional one, and embeds a core material that does not separate from the low-melting alloy in the low-melting alloy, and forms the primary molded article containing the core at the time of molding. A low melting point alloy core that has a compressive strength that does not deform even when pressure is applied and that can be removed by a simple operation of heating after molding of the primary molded product, and that can form a final molded product with a precise hollow shape And a method for manufacturing the same.

[Means for solving the problem]

In order to achieve the above object, the low-melting alloy core of the present invention comprises a heat-resistant fiber bundle inside a bag-shaped coating formed by knitting heat-resistant fiber yarn to a coarse mesh through which a fluid flows. and/
Alternatively, a core material is formed by filling a cotton-like material, and the core material is embedded in a low-melting-point alloy, and the core material is filled with a low-melting-point alloy. The manufacturing method of the alloy core was formed in a bag shape by knitting a thread of a heat-resistant fiber to the roughness of a fluid-injected surface in a casting cavity formed by an upper casting mold and a lower casting mold that are in contact with and separated from each other. A core material formed by packing a bundle of heat-resistant fibers and / or cotton-like material is disposed inside the coating, and a low-melting alloy melted by a pressure penetrating into the core material is filled in the casting cavity. Then, there is provided a means for cooling the upper and lower casting molds to a temperature equal to or lower than the melting point of the low melting point alloy.

[Action]

By adopting the above configuration and means, the present invention will not be deformed even by molding pressure when molding a primary molded article containing a core, and a core having such properties is simply and It can be manufactured reliably.

〔Example〕

 Hereinafter, embodiments of the present invention shown in the drawings will be described.

1 (a) and 1 (b) show an embodiment of a low melting point alloy core according to the present invention.
A bundle of heat-resistant fibers 3b is packed inside a covering 3a formed by knitting a yarn of heat-resistant fiber to the roughness of the eyes into which the fluid flows, and forming a core material 3. The core material 3 is embedded in the melting point alloy 2 and is filled with the low melting point alloy 2 to form a core having a substantially U-shaped cross section.

The core material 3 embedded in the low melting point alloy core 1 according to the present invention.
Is formed into a shape slightly smaller than the core shape as shown in FIG. 2 (a), and heat-resistant fiber yarns are formed as shown in FIG. 2 (b). As shown in FIG. 2 (c), a bundle 3b of heat-resistant fibers is arranged in the axial direction of the core and packed in a cover 3a formed in a bag shape by knitting to a roughness.

As shown in FIG. 3, another example of the core material 3 embedded in the low-melting alloy core 1 according to the present invention is a bundle of heat-resistant fibers outside the inside of a bag-like coating 3a similar to the above. 3b are arranged in the axial direction of the core, and the center portion thereof is formed by filling a cotton-like material 3c of heat resistant fiber. The core material 3 used for the low melting point alloy core 1 of the present invention is Any material may be used as long as it is formed by packing the bundle 3b of heat-resistant fibers and / or the cotton-like material 3c in the bag-like covering 3a.

Thread of heat-resistant fiber used for the coating 3a of the core material 3 and bundle 3b of heat-resistant fiber filled inside the coating 3a
As the heat-resistant fiber used for the heat-resistant fiber flocculent material 3c, one that does not deteriorate even when exposed to a temperature higher than the melting point of the low-melting alloy 2 by 80 ° C. or more is preferable. For example, carbon fiber, E glass fiber, Examples include inorganic fibers such as alumina fibers and silicon carbide whiskers, organic fibers such as aramid fibers and nylon fibers, and metal fibers that do not form an alloy with the low melting point alloy 2 such as stainless steel fibers and copper fibers.

The low-melting alloy 2 used for the low-melting alloy core 1 according to the present invention is preferably an alloy having a melting point of 70 to 250 ° C., such as tin (Sn), bismuth (Bi), lead (Pb), and cadmium. (C
d), an alloy containing 2 to 4 metal elements selected from the group of zinc (Zn) and antimony (Sb) is preferable,
For example, (1) Bi / Pb / Sn / Cd = 50 / 26.7 / 13.3 / 10 (melting point
70 ° C), (2) Bi / Pb / Cd = 51.65 / 40.20 / 8.15 (melting point 91.5
° C), (3) Bi / Sn = 57/43 (melting point 138.5 ° C), (4) Pb /
Sn = 38.1 / 61.9 (melting point 183 ° C.), (5) Sn / Zn = 91/9 (melting point 199 ° C.), (6) Pb / Sb = 87.5 / 12.5 (melting point 247 ° C.) and the like.

In the low melting point alloy core 1 according to the present invention configured as described above, the heat-resistant fiber bundle 3b and / or the floc
The core material 3 formed by filling the inside of the bag-shaped cover 3a with 3c is embedded in the low melting point alloy 2 and the inside of the core material 3 is also filled with the low melting point alloy 2, so that only the low melting point alloy is used. In comparison with the core consisting of, the low-melting alloy core 1 according to the present invention exhibits more than twice the compressive strength, and even near the melting point temperature of the alloy, the compressive strength decreases with respect to room temperature by about 1/2. It has been greatly improved over the single one.

As shown in FIGS. 4 and 5, the casting mold used in the method of manufacturing the low melting point alloy core 1 of the present invention moves so as to be in contact with and separate from the upper casting mold 11. A casting cavity 13 is formed when the two molds 11 and 12 come into contact with each other, and the upper casting mold 11 has an inlet for introducing the molten low melting point alloy 2 into the casting cavity 13. 14 is formed, and an air vent hole 15 connected to the casting cavity 13 is formed on the divided surface of the two dies 11 and 12.

In order to manufacture the low melting point alloy core 1 according to the present invention using the casting mold configured as described above, first, the upper and lower casting molds 11 and 12 are opened and the casting cavity 13 is After arranging the core material 3, the molds 11 and 12 are clamped.
A low-melting alloy 2 previously melted at a temperature 5 to 80 ° C. higher than the melting point from the inlet 14 is filled into the casting cavity 13 in which the core material 3 is disposed.

The filling pressure of the low melting point alloy 2 at this time is a pressure at which the low melting point alloy 2 in a molten state can penetrate into the core material 3,
After filling the low-melting alloy 2 into the casting cavity 13 including the inside of the core material 3, the first and second casting dies 11 and 12 are cooled to a temperature lower than the melting point of the low-melting alloy 2. After casting, both molds 1
Open 1 and 12, and cast a low melting point alloy core
3 and the burrs are cut to obtain a low melting point alloy core 1 according to the present invention.

Further, it is preferable that the upper and lower casting dies 11 and 12 are preliminarily heated to a temperature lower by 5 to 50 ° C. than the melting point of the low melting point alloy 2 before casting.
Is preferably lower than the melting point of the low melting point alloy 3 by 3 ° C. or more.

Low melting point alloy core 1 of the present invention cast as described above
In the manufacturing method, the core material 3 formed by packing the heat-resistant fiber bundle 3b and / or the cotton-like material 3c inside the bag-shaped covering 3a does not separate from the low-melting-point alloy 2, 3 can be embedded in the low melting point alloy 2 and the core material 3 is filled with the low melting point alloy 2.

The low-melting alloy core 1 according to the present invention manufactured by the above method is used as a core of a molding die such as compression molding, injection molding, transfer molding, etc., to form a final molded product having a precise hollow portion. Is what you can do.

Hereinafter, an example of forming a final molded product having a hollow portion using the low melting point alloy core of the present invention will be described.

First, the low melting point alloy core 1 according to the present invention is placed at a predetermined position in a molding cavity of a molding die for molding a primary molded article containing a core.
After arranging, the molding material such as resin is filled in the molding cavity, and after molding for a predetermined time, the molded product is taken out from the molding die.
A primary molded article incorporating the low melting point alloy core 1 is obtained.

Next, the primary molded article containing the low-melting alloy core 1 obtained above is heated to a temperature not lower than the melting point of the low-melting alloy 2 and not higher than the temperature at which the primary molded article is thermally deformed. Heating by means such as induction heating or the like, the low-melting alloy 2 of the low-melting alloy core 1 is melted and removed, and the core material 3 remaining in the hollow portion after the low-melting alloy 2 is melted is removed to obtain a final molded product. obtain.

The low melting point alloy core 1 according to the present invention is injection molded,
The molding material which can be applied to any molding method such as compression molding and transfer molding, and which can be molded using the low melting point alloy core 1 described above, does not deteriorate or thermally deform even near the melting point temperature of the low melting point alloy 2. For example, thermoplastic resins include polyamide resins such as nylon 6, nylon 6,6, nylon 4,6, nylon 11, and nylon 12, polybutylene terephthalate, polyphenylene sulfide, polyethylene, and propylene. , Polycarbonate, polyacetal, etc., and the thermosetting resin includes phenol, unsaturated polyester, silicone, epoxy, urea, etc.

〔The invention's effect〕

According to the present invention, as described above, a core material that does not separate from the low melting point alloy is embedded in the low melting point alloy, and the low melting point alloy is filled inside the core material to compress the low melting point alloy core. Strength can be increased, it has a compressive strength that does not deform even when molding pressure acts on the primary molded product containing the core, and only the core is heated by a simple operation of heating after molding the primary molded product And has an excellent effect such that a molded article having a precise hollow portion can be formed.

[Brief description of the drawings]

1 (a) and 1 (b) show an embodiment of a low melting point alloy core according to the present invention. FIG. 1 (a) is a perspective view, and FIG. 1 (b) is I in FIG. 1 (a). -I line sectional explanatory view, FIG. 2 (a)
(B) and (c) show a first embodiment of a core material embedded in a low melting point alloy core according to the present invention. FIG. 2 (a) is a front view, and FIG. 2 (b) is an enlarged surface explanatory view. FIG. 2 (c) is a cross-sectional explanatory view taken along the line II-II of FIG. 2 (a), and FIG. 3 is a cross-sectional explanatory view of a second embodiment of the core material embedded in the low melting point alloy core according to the present invention. 4 and 5 (a) and 5 (b) are explanatory views of a casting mold for producing a low melting point alloy core according to the present invention. FIG. 4 is a sectional explanatory view, and FIG. 5 (a) is a lower view. Perspective view of casting mold, fifth
FIG. 5B is a cross-sectional explanatory view taken along the line VV in FIG. 5A. DESCRIPTION OF SYMBOLS 1 ... Low melting point alloy core 2 ... Low melting point alloy 3 ... Core material 3a ... Coating body 3b ... Fiber bundle 3c ... Fiber cotton-like material 11 ... Top casting mold 12 ... Bottom casting mold 13 …… Casting space 14 …… Inlet 15 …… Air vent hole

Claims (2)

(57) [Claims] 1. A heat-resistant fiber bundle (3b) and / or a cotton-like material (3) are formed inside a cover (3a) formed by knitting heat-resistant fiber yarns to a coarse mesh into which a fluid flows and forming a bag. 3c) is filled to form a core material (3), and the core material (3) is embedded in the low melting point alloy (2), and the inside of the core material (3) is filled with the low melting point alloy (2). A low melting point alloy core characterized by the following. 2. The method according to claim 1, wherein a heat-resistant fiber yarn is injected into a casting cavity (13) formed by an upper casting mold (11) and a lower casting mold (12) which are in contact with and separated from each other. A core material (3) formed by packing a heat-resistant fiber bundle (3b) and / or a cotton-like material (3c) inside a knitted and bag-shaped cover (3a) is provided.
After filling the casting cavity (13) with the low melting point alloy (2) melted under the pressure penetrating into the core material (3), the upper and lower casting dies (11) and (12) are filled with the low melting point alloy. A method for producing a low melting point alloy core, comprising cooling the alloy to a temperature lower than the melting point of the melting point alloy (2).