HK1036240B

HK1036240B - Method and apparatus for production of cast article having small hole

Info

Publication number: HK1036240B
Application number: HK01106746.3A
Authority: HK
Inventors: 山口正志; 佐藤正纪; 长滨秀信
Original assignee: Ykk株式会社
Priority date: 1999-11-04
Filing date: 2001-09-25
Publication date: 2005-04-08

Description

Method and apparatus for producing cast product with small hole

Technical Field

The present invention relates to a method and apparatus for producing a cast product having small holes. The present invention relates particularly to a metal die casting technique, and more particularly to a pinhole forming technique which can be used for producing a cast article having a pinhole, particularly an optical connector member of the ferrule and capillary type, by metal die casting of an amorphous alloy (metallic glass).

As a typical example of a molded article having a small hole and requiring high dimensional accuracy, a sleeve or a capillary of an optical connector can be cited.

Background

Referring now to the drawings, FIG. 1 shows an optical connector ferrule 10 of one-piece construction, including a capillary portion 11 and a flange portion 12. The capillary portion 11 of the ferrule 10 has a small-diameter through hole 13 formed along its axis, which is adapted to be inserted with an optical fiber 17 (or a base wire of an optical fiber coated with a plastic film), and a flange portion 12 having a large-diameter through hole 14 formed along its axial direction, which is adapted to be inserted with a jacketed optical fiber 16 (jacketed optical fiber). The small-diameter through hole 13 and the large-diameter through hole 14 are connected to each other by an inclined portion 15. The connection of the optical fibres 17, 17 in pairs is obtained by: the ends of the sleeves 10, 10 into which the optical fibres have been inserted and connected are brought together and inserted into the split sleeve 18. As a result of this, the optical fibres 17, 17 have abutting and joined front ends, the axes of which are aligned with each other.

Fig. 2 shows another form of optical connector ferrule 10a, which includes a capillary portion 11a and a flange portion 12a as a separate member.

The diameter of the hole into which the optical fiber is inserted depends on the type of the ferrule, and for example, the SC type capillary (ferrule) has a hole with a diameter of 0.126mm and a length of 10 mm.

Previously, sleeves were made of ceramic materials such as zirconium dioxide. The apertures in the sleeve are formed by injection molding a sleeve blank of ceramic material having smaller apertures, calcining the sleeve blank of ceramic material, and then linearly overlapping the calcined blank of ceramic material to form a finished product having a particular size. In addition, the sleeve for producing a ceramic material includes many machining steps such as grinding of the outer diameter and machining of the tip into a circular convex surface (PC machining) or the like in addition to the above-described inner diameter machining. Therefore, the production method takes a long time and the production cost is large.

As a method for solving the above-mentioned problems, the assignee of the present application has proposed a method of combining a general technique based on a metal die casting method with an amorphous alloy existing in a glass phase transition region to make a molded article of the amorphous alloy satisfy predetermined shape, dimensional accuracy and surface quality and efficiently mass-produce by a simple method, even if the article has a small hole as in an optical connector ferrule or an article of a complicated shape [ japanese patent application laid-open (kokai) No.10-186176 ]. In the production method of an amorphous alloy molded article having a pinhole disclosed in the patent document, the pinhole is formed basically by injecting a molten material capable of producing an amorphous alloy into a mold cavity having a core rod group at a high speed and then pulling out the core rod from the resulting cast product to form the pinhole.

To produce a cast article having a small bore, a mandrel uniformly coated with a sloughable medium is typically used. Since the removable medium is rapidly volatilized when the core rod is brought into contact with the molten metal, bubbles or flaws remain in the cast product, and the direction of volatilization of the removable medium cannot be uniformly and constantly controlled, there arises a problem that the dimensional accuracy of the pinholes is inferior to that required. On the contrary, when the injection pressure is reduced during casting to obtain a cast product with high precision, other problems arise such as the core rod cannot be pulled out from the cast product because there is no gap between the cast material and the core rod forming the small hole. In addition, there is a possibility that the surface of the core rod may be scratched or even the core rod may be damaged during casting or in an operation of pulling out the core rod after casting. Since the core rod is made of an internally sintered hard metal or cemented carbide, it is expensive and scratching or damaging the core rod to make it unusable is an important factor increasing the cost of the product.

These problems are not specific to optical connector ferrules or capillaries, but are prevalent in die-cast metal moldings having small holes.

Disclosure of Invention

Accordingly, it is a primary object of the present invention to provide a method and apparatus for producing a cast product in a short time at a low cost with high productivity, which can eliminate various problems caused by the difficulty in pulling out a mandrel from a cast product after casting and the above-mentioned problem of the life of the mandrel.

It is a further specific object of the present invention to provide a method and apparatus for providing a molded article satisfying predetermined shape, dimensional accuracy and surface quality by a simple method, even if the article is a molded article of an amorphous alloy having elongated small holes, an inexpensive molded article of an amorphous alloy having small holes, particularly an optical amorphous connector of a ferrule or capillary type; and the product has excellent performance in the aspects of service life, mechanical strength, impact resistance and the like.

To achieve the above object, a first aspect of the present invention provides a method of producing a cast product having a small hole.

A first embodiment of the method according to the invention is characterized in that: in the casting of molten metal, molten metal is poured into a metal mold cavity having a linear core member of a desired sectional shape previously set therein, to thereby produce a cast product, a linear core member having a surface film coated or treated with a surface is used as the linear core member, and the linear core member is pulled out from the cast product after casting to form a small hole substantially equal to the sectional shape of the linear core member in the cast product. In this case, a preferable form is such that when the core wire is drawn out from the product after casting, a part or all of the surface film is peeled off, thereby allowing the linear core member to be drawn out from the cast product.

A second embodiment of the invention is characterized in that: the method includes injecting molten metal into a cavity of a metal mold having a linear core member of a desired sectional shape previously set therein, thereby producing a cast product, pulling out the linear core member from the cast product to form a small hole having a sectional shape of the linear core member, the linear core member being configured to be elastically deformed in a pulling-out direction so that a diameter thereof is smaller than an original diameter when pulled out from the cast product after casting, thereby allowing the linear core member to be pulled out from the cast product.

A second aspect of the present invention provides an apparatus for producing a cast product having a small hole, characterized in that it comprises: a metal mold having a cavity defining the outer shape of the product, a movable cylindrical guide having a central hole, which is slidably disposed in the mold so as to be extendable into and retractable from the cavity; a linear core member disposed in the mold through the center hole of the cylindrical guide member; preferably, the apparatus further comprises means for applying a tensile load, preferably no more than 1960N/mm, to the linear core in the longitudinal direction²。

By using the above method and apparatus, a sleeve or capillary tube having a small-hole cast product, particularly an amorphous alloy molded product, particularly an optical connector, can be manufactured with high productivity.

Drawings

Other objects, features and advantages of the present invention will become more apparent from the following description with reference to the accompanying drawings, in which:

fig. 1 is a fragmentary cross-sectional view showing an optical connector ferrule of one-piece construction including a capillary portion and a flange portion,

FIG. 2 is a fragmentary cross-sectional view showing another optical connector ferrule including a capillary portion and a flange portion as a separate component;

FIGS. 3A-3C are fragmentary cross-sectional views, showing one embodiment of the steps for producing the cast article of the invention,

fig. 4 is a fragmentary cross-sectional view showing another embodiment of the method of the present invention employing a linear core coated with a face film,

fig. 5 is a fragmentary cross-sectional view, which still shows a further embodiment of the method of the invention using a linear core made of a material susceptible to elastic deformation,

fig. 6 is a fragmentary cross-sectional view showing a further embodiment of an apparatus for producing a cast article according to the invention,

fig. 7 is a sectional view showing a molded article produced by the apparatus of fig. 6.

Detailed Description

In view of the difficulty in drawing out the linear core from the cast product after casting, or the problems caused by the above-described aspect of the life of the linear core, the method of producing a cast product of the present invention improves the drawing characteristics of the linear core. The following method can be used to improve the draw characteristics of the cast linear core. In the following description, the linear core member is referred to as a "wire".

(1) A method of subjecting the wire to surface coating or surface treatment.

The method is to coat the surface of the wire with a thin film that is easily peeled off, or to use a wire that is expected to form a film during production, thereby allowing the wire as a linear core member to be easily separated from the cast product. With this method, when the wire is drawn out from the cast product, the surface film is partially or entirely peeled off from the wire, because the surface film of the wire is closely adhered to the cast product, and therefore only the wire is separated from the cast product. As a result, small holes having a cross-sectional shape of lines are formed in the cast product.

The surface film of the wire may be formed by depositing materials, such as oxides, nitrides and carbides on the surface of the wire by Physical Vapor Deposition (PVD) and Chemical Vapor Deposition (CVD) or by thermal dipping of metals such as electroplating, electroless plating. When the wire is made of an active metal material, a wire having a certain content of oxide, nitride or carbide thin film may be used without heat treatment during the production process. The required film thickness ranges from about 0.5 μm to about 100 μm in terms of the peelability characteristics of the film and the drawability characteristics of the wire. In this method, various materials can be used as the wire material. Among other wires, titanium-based alloys having excellent thermal resistance have proved to be particularly advantageous.

(2) Methods using elastic or superelastic wires.

This method uses a wire having a high elastic limit as the wire (linear core wire). By using such a wire, the wire is elastically deformed in the drawing direction when it is drawn out of the cast product, and therefore its diameter becomes smaller with respect to the small hole formed in the cast product, and as a result, the wire can be drawn out of the cast product due to the gap that occurs between the wire and the cast product, forming the small hole of the cross-sectional shape of the wire in the molded product. As the above-described wire, an elastic material, a high tensile strength steel, and a superelastic material (Ni — Ti superelastic alloy, etc.) can be used.

The above methods (1) and (2) may sometimes be used in combination.

According to the present invention, in order to protect the wire (linear core member) in the metal mold cavity or during casting, a metal mold having a movable cylindrical guide member slidably placed in the mold so as to protrude into and withdraw from the cavity may be used. When the wire is placed in the mould cavity together with the cylindrical guide, the wire passes through the central hole of the guide and is stretched in the length direction of the wireThe load is preferably not more than 1960N/mm². With the general use of such cylindrical guides, the portion of the wire covered with the guide is protected from contact with the molten metal, the surface area of the wire in contact with the cast product becomes smaller, with the result that the possibility of scratching or damaging the wire during the drawing step is reduced. In addition, since a tensile load is applied to the wire, it is possible to prevent the wire from being bent when the molten metal is injected into the mold cavity. Therefore, a cast product having a high-precision small hole can be produced. In addition, the present method may be used in combination with one or both of the above methods.

The size of the wire may vary depending on the diameter of the desired aperture. In the case of the optical connector member, the size of the wire is set to a range of 0.025mm to 1mm in diameter.

Although the casting material used in the method of the present invention is not necessarily limited to any particular substance, it may be any material used in a usual casting method, and an amorphous alloy containing an amorphous phase at least 50% by volume may be preferably used. Among other amorphous alloys in the present specification, an amorphous alloy having a composition represented by one of the following general formulas (1) to (6) may be preferably used.

M¹ _aM² _bLn_cM³ _dM⁴ _eM⁵ _f …(1)

Wherein: m¹Represents two elements, one or two of Zr and Hf; m²Represents at least one element selected from the group consisting of: ni, Cu, Fe, Co, Mn, Nb, Ti, V, Cr, Zn, Al and Ga, Ln represents at least one element selected from the group consisting of: y, La, Ce, Nd, Sm, Gd, Tb, Dy, Ho, Yb and Mm (Mish metal: rare earth element aggregate); m³Represents at least one element selected from the group consisting of: be. B, C, N and O; m⁴Represents at least one element selected from the group consisting of: ta, W and Mo; m⁵Represents at least one element selected from the group consisting of: au, Pt, Pd, and Ag; a, b, c, d, e and f represent the atomic proportionsRespectively satisfying 25 < a < 85 >, 15 < b < 75 >, 0 < c < 30, 0 < d < 30, 0 < e < 15, and 0 < f < 15.

The amorphous alloy includes alloys represented by the following general formulae (1-a) to (1-p).

M¹ _aM² _b …(1-a)

Due to M²The element and Zr or Hf coexist, so the amorphous alloy has large negative enthalpy of mixing and good machinability of an amorphous structure.

M¹ _aM² _bLn_c …(1-b)

The addition of rare earth elements to the alloy represented by the above general formula (1-a) enhances the thermal stability of the amorphous structure as an amorphous alloy.

M¹ _aM² _bM³ _d …(1-c)

M¹ _aM² _bLn_cM³ _d …(1-d)

With M having a small atomic diameter³The element (Be, B, C, N or O) fills the interstitial spaces in the amorphous structure, as such amorphous alloys, stabilizing the structure and enhancing the producibility of the amorphous structure.

M¹ _aM² _bM⁴ _e …(1-e)

M¹ _aM² _bLn_cM⁴ _e …(1-f)

M¹ _aM² _bM³ _dM⁴ _e …(1-g)

M¹ _aM² _bLn_cM³ _dM⁴ _e …(1-h)

Mixing high melting point metal M⁴(Ta, W or Mo) is added to the above alloys as such amorphous alloys to enhance heat and corrosion resistance without affecting the producibility of the amorphous structure.

M¹ _aM² _bM⁵ _f …(1-i)

M¹ _aM² _bLn_cM⁵ _f …(1-j)

M¹ _aM² _bM³ _dM⁵ _f …(1-k)

M¹ _aM² _bLn_cM³ _dM⁵ _f …(1-l)

M¹ _aM² _bM⁴ _eM⁵ _f …(1-m)

M¹ _aM² _bLn_cM⁴ _eM⁵ _f …(1-n)

M¹ _aM² _bM³ _dM⁴ _eM⁵ _f …(1-o)

M¹ _aM² _bLn_cM³ _dM⁴ _eM⁵ _f …(1-p)

Such amorphous alloys contain a noble metal M⁵(Au，Pt，Pd, or Ag) which are not easily broken even if they are crystallized.

Al_1000-g-h-iLn_gM⁶ _nM³ _i …(2)

Wherein Ln represents at least one element selected from the group consisting of: y, La, Ce, Nd, Sm, Gd, Tb, Dy, Ho, Yb and Mm; m⁶Represents at least one element selected from the group consisting of: ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Hf, Ta and W; m³Represents at least one element selected from the group consisting of: be, B, C, N and O; g, h, and i represent the ratio of these atoms, which satisfy 30. ltoreq. g.ltoreq.90, 0. ltoreq. h.ltoreq.55, and 0. ltoreq. i.ltoreq.10, respectively.

The above amorphous alloy includes alloys represented by the following general formulae (2-a) and (2-b).

AI_100-g-hLn_gM⁶ _h …(2-a)

This amorphous alloy has a large negative enthalpy of mixing and good producibility of the amorphous structure.

AI_100-g-h-iLn_gM⁶ _hM³ _i …(2-b)

The amorphous alloy has a stable structure and enhances the producibility of the amorphous structure due to the use of M having a small atomic diameter³Elements (Be, B, C, N, or O) fill the gaps in the amorphous structure.

Mg_100-pM⁷ _p …(3)

Wherein M is⁷Represents at least one element selected from the following group of elements: cu, Ni, Sn and Zn; p represents an atomic proportion falling within the range of 5. ltoreq. p.ltoreq.60.

This amorphous alloy has a large negative enthalpy of mixing and the producibility of an amorphous structure.

Mg_100-g-rM⁷ _qM⁸ _r …(4)

Wherein M is⁷Represents at least one element selected from the following group of elements: cu, Ni, Sn and Zn; m⁸Represents at least one element selected from the following group of elements: al, Si and Ca; q and r represent atomic ratios satisfying 1. ltoreq. g.ltoreq.35 and 1. ltoreq. r.ltoreq.25, respectively.

In this alloy, M having a small atomic diameter (Al, Si or Ca) is used⁸The elements fill the interstices of the amorphous structure of the alloy of formula (3) above, stabilizing the structure and enhancing the producibility of the amorphous structure.

Mg_100-q-sM⁷ _qM⁹ _s …(5)

Mg_100-q-r-sM⁷ _qM⁸ _rM⁹ _s …(6)

Wherein M is⁷Represents at least one element selected from the following group of elements: cu, Ni, Sn and Zn; m⁸Represents at least one element selected from the following group of elements: al, Si and Ca; m⁹Represents at least one element selected from the following group of elements: y, La, Ce, Nd, Sm and Mm; q, r and s represent atomic proportions satisfying 1. ltoreq. q.ltoreq.35, 1. ltoreq. r.ltoreq.25, and 3. ltoreq. s.ltoreq.25, respectively.

The addition of rare earth elements to the alloys of general formulae (3) and (4) above enhances the thermal stability of the amorphous structure for such amorphous alloys.

Among the other amorphous alloys mentioned above, Zr-TM-Al and Hf-TM-Al (TM: transition metal element) amorphous alloys having a wide difference between the glass transition temperature (Tg) and the crystallization temperature (Tx) exhibit high strength and corrosion resistance, have a wide supercooled liquid region (glass transition region), and in the case of Zr-TM-Al amorphous alloys, have a Δ Tx-Tg of not less than 30K, and a very wide supercooled liquid region of not less than 60K. Within the above temperature range, these amorphous alloys exhibit very satisfactory workability, being viscous fluid even at pressures not greater than several tens Mpa. They are characterized by their ease of production and their stability, which is evidenced by the fact that they can be made into amorphous bulk materials even with casting processes with cooling rates on the order of tens of K/s. By using viscous fluids in the glass transition range, these alloys produce amorphous materials and can be replicated exactly according to the size and shape of the molding cavity of the metal mold.

The Zr-TM-Al and Hf-TM-Al amorphous alloys employed in the present invention have a wide range of Δ Tx, although variations in alloy composition and determination may be made. For example, Zr₆₀Al₁₅CO_2.5Ni_7.5Cu₁₅The alloys (Tg: 652K, Tx: 768K) have a very broad Δ Tx as 116K. It also provides very satisfactory oxidizability, with little oxidation even when heated completely to high temperatures of Tg. The alloy has a Vickers hardness of up to 460(DPN), a tensile strength of up to 1600MPa, and a flexural strength of up to 3000MPa at temperatures from room temperature to temperatures near Tg. The coefficient of thermal expansion α of the alloy is as small as 1X 10 from room temperature to a temperature close to Tg^-5And the Young's modulus is 91Gpa, and the elastic limit of a compressed state exceeds 4-5%. In addition, the toughness of the alloy is as high as that of the alloy with the charpy impact value of 60-70KJ/m²Within the range of (1). This alloy, while exhibiting the high strength properties described above, also has a flow pressure as low as approximately 10MPa when it is heated to the glass transition range. Therefore, the alloy is characterized by being very easy to machine, and capable of being made into tiny parts with complicated shapes and high-precision parts by low pressure. In addition, due to the nature of the so-called glass (amorphous) material, such alloys are characterized by a very high smoothness of the surface upon manufacture of the finished product and by the substantial absence of the possibility of steps forming that may occur when slip bands appear on the surface during deformation of crystalline alloys.

Amorphous alloys typically begin to crystallize as it is heated to the glass transition range and held within that range for extended periods of time. Conversely, the above alloys having a broad Δ Tx range as described above have a stable amorphous phase when the temperature is maintained within a suitably selected Δ Tx range, avoiding any crystallization for a period of up to two hours. Thus, users of such crystals do not have to worry about crystallization during standard molding processes.

The above alloys are fully capable of exhibiting these properties during the transition from the molten state to the solid state. In general, rapid cooling is required to produce amorphous alloys, which in contrast allow bulk materials of a single amorphous phase to be readily produced from the molten state at a cooling rate of about 10K/sec, with the subsequent formation of solid bulk materials having very smooth surfaces. This alloy has a transitivity that allows good replication even of micro-scale scratches on the surface of the metal mold due to polishing.

Therefore, when the above alloy is used as a casting material, the metal mold for producing a molded article is only required to have its surface adjusted to meet the surface quality expected of the molded article, because the cast article can fully reproduce the surface quality of the metal mold. Therefore, in a general casting method of a metal mold, the alloy can omit or eliminate a step of adjusting the size and surface roughness of a molded article.

The properties of the amorphous alloy described above include the combination of the following properties: lower hardness, high tensile strength, high flexural strength, lower Young's modulus, high elastic limit, high impact resistance, high abrasion resistance, smooth surface, and high precision castability or processability, which make such alloys useful as molding materials for various applications, such as sleeves or sleeves for optical connectors. In addition, the amorphous alloy has high-precision castability and machinability, and also has excellent transferability of the shape of the replica cavity, so that a molded article satisfying dimensional specifications, dimensional accuracy and surface quality can be manufactured by a metal die casting method and a molding method with high overall productivity using a simple production process using a suitably prepared mold. The excellent transferability of amorphous alloys fully replicates the shape of the mold cavity, meaning that there is little clearance between the mold cavity surface and the cast product. This fact therefore poses a problem that, when the core rod is extracted from the die, the core rod is damaged or broken because the core rod for forming the inside of the small hole is elongated to have insufficient strength as described above. The present invention solves this problem and is particularly advantageous for producing moulded articles of amorphous alloys having small pores.

When the cast product of the present invention is produced from a metallic material, the following alloys may be advantageously used as die castings in addition to the above amorphous alloys: al-based alloys, Mg-based alloys, Zn-based alloys, Fe-based alloys, Cu-based alloys, titanium-based alloys, and the like. Such die cast alloys can be used in conventional casting methods and are relatively inexpensive compared to the ceramic and amorphous alloys typically used to produce optical connector components. By using such an alloy as a die cast, the alloy can be molded by a die casting machine under the pressure of a metal mold, whereby the optical connector member can be easily produced.

For the Al-based alloy used as die casting, Al-Si, Al-Mg, Al-Si-Cu or Al-Si-Mg aluminum alloys of the classification symbols ADC1, ADC5 and ADC12 according to JIS (Japanese Industrial Standard) can be preferably used, and ADC12 proves particularly advantageous among the other alloys mentioned above. Also, for Mg-based alloys for use as die castings, Mg-Al or Mg-Al-Zn magnesium alloys of MDC1A, MDC2A and MDC3A may be preferably used, and MDC1A has proved particularly advantageous among the other alloys mentioned above. For Zn-based alloys for use as die castings, Zn-Al-Cu-Mg or Zn-Mn-Cu zinc alloys of AG40A, AG41A and high Mn alloys can be used with preference, high Mn alloys proving to be very advantageous among the other alloys mentioned above. For Fe-based alloys, gray cast iron, austenitic cast iron, and stainless cast steel may be used. Among the other alloys mentioned above, stainless cast steel has proven to be particularly advantageous. For Cu-based alloys, brass, bronze and aluminum bronze may be used. Of the other alloys mentioned above, aluminum bronze has proven to be particularly advantageous. Typical examples of the titanium alloy include an α -type alloy, a β -type alloy, and an α + β -type alloy. Among the other alloys mentioned above, the α + β type alloys prove to be very advantageous.

Among the other alloys mentioned above, Fe-M-X alloys represented by the following general formula have proved to be particularly advantageous

Fe_xMyXz

Wherein M represents Ni and/or Co, and X represents at least one element selected from the group consisting of: mn, Si, Ti, Al and C; x, Y and Z represent weight percentages, and the range is 30-40Y, 0-10Z, X is the balance including inevitable impurities. Since the Fe-M-X alloys represented by the above general formula allow machining with high dimensional accuracy and have a thermal expansion coefficient close to that of the optical fiber, they are well suited for the material of the ferrule in which the optical fiber is fixed.

Some embodiments of the present invention will be described in more detail below with reference to the accompanying drawings.

Fig. 3A illustrates the structure of a method and apparatus for producing a cast product with small holes according to the present invention. In fig. 3A, 3B, reference numeral 1 denotes a detachable metal mold having cavities 2, 3 suitable for determining the outer dimensions of the product, representing an elongated thread (linear core) which has been surface-coated or surface-treated, or made of a material with a high elastic limit (linear core).

The mold 1 may be made of, for example, copper, a copper alloy, a sintered hard metal, or a sintered carbide, and a flow passage allowing a fluid, a gas, or the like of a cooling medium or a heating medium to flow may be provided in the mold 1. The surface of the wire 3 may be coated with a thin film of Ti2, TiN, TiC, etc., or the wire 3 may be made of spring steel, high tensile strength steel and superelastic material, or a material having a combination of the two.

Sometimes in order to prevent the molten metal from forming an oxide film, it is preferable to place the apparatus in a vacuum or in an atmosphere of an inert gas such as Ar gas, or to establish a flow of an inert gas in an injection region of the molten metal.

In the production of such a cast product, molten metal (not shown) is injected into the cavity 2 of the mold 1 to cast a product. When the mold is cooled to a temperature at which the mold is cooled to a temperature not higher than the melting point of the molten metal (not higher than the glass transition temperature Tg in the case of an amorphous alloy), the mold 1 is separated to extract the cast product 4 of the fixed wire 3, as shown in fig. 3B.

Thereafter, the wire 3 is pulled out from the finished cast product to obtain a cast product 4 having small holes 5 as shown in fig. 3C.

FIG. 4 shows an example of the use of a coating of TiO as described above₂And a surface film 6 of TiN, TiC, or the like. By using the wire 3 coated with such a surface film 6 in advance, when the wire is pulled out, only the wire 3 is pulled out from the cast product 7 due to the peeling of the surface film 6 from the wire 3, thereby forming a pinhole.

Fig. 5 shows another embodiment using a wire 3, the wire 3 being made of a material with a high elastic limit, such as spring steel, high tensile strength steel and superelastic material. By using the wire 3 made of a material having a high elastic limit, when the wire is pulled out, a small gap is formed between the wire 3 and the cast product 7 due to the elastic deformation of the wire 3 itself, with the result that the wire 3 can be pulled out from the cast product 7 to form a small hole in the cast product.

Fig. 6 shows the structure of another mode of carrying out the method and apparatus for producing a cast product of the present invention. In fig. 6, reference numeral 8 denotes a movable cylindrical guide which can slide in the mold so as to extend into and out of the cavity 2 of the mold 1. The wire 3 is mounted in the cavity 2 of the die 1 together with a movable cylindrical guide 8 by passing the wire through the central hole of the guide 8. By using such a cylindrical guide 8, the portion of the wire 3 covered by the inner guide is protected from contact with the molten metal, so that the surface area of the wire in contact with the cast product becomes small, thus greatly reducing the possibility of damaging the wire 3 during drawing.

In addition, since the tensile load is applied in the longitudinal direction of the wire 3, the accidental bending of the wire 3 can be effectively prevented when the molten metal flows into the mold cavity in the transverse direction of the wire 3 or the turbulence of the molten metal occurs in the mold cavity. This makes it possible to form a high-precision pinhole in the cast product.

Fig. 7 shows a cast product 4a produced by the apparatus shown in fig. 6 described above, with the lower part separated from the cast product. The cast product 4a has a small diameter portion 5a and a large diameter portion 5 b. The length of the large diameter portion 5b can be adjusted artificially according to the variation in the length of the movable cylindrical guide 8 inserted into the cavity 2 of the die 1. Sometimes the small diameter portion 5a may be rubbed by the wire 3 as desired.

Although the elongated wire 3 having a uniform diameter over the entire length is used in the above embodiment, a wire (linear core member) having a diameter gradually increased in the drawing direction may be used so as to form small holes having an inner diameter gradually increased in the axial direction. In addition, when the movable cylindrical guide 8 as shown in fig. 6 is employed, small holes having various sectional shapes can be formed by employing guides having various sectional shapes. Although the above description is directed to the embodiment of manufacturing a cast product having a small hole, a cast product having a blind hole can also be manufactured by adjusting the length of the linear core member entering the cavity of the mold (insertion length).

According to the method and apparatus of the present invention, as described above, the problems caused by the difficulty in drawing out the linear core member from the cast product after casting or the problem of the service life of the core member are eliminated, and a cast product with a pinhole can be produced at low cost, high productivity and in a short time. Thus, the present invention can provide a molded article of amorphous alloy having fine pores, particularly an optical conductor member of the sleeve or capillary type, which is excellent in durability, mechanical strength, impact resistance, etc., at low cost, even if the molded article is a molded article of amorphous alloy having elongated pores, by a simple method, and satisfies predetermined shape, dimensional accuracy and surface quality.

The present invention will now be described more specifically with reference to operation examples, each of which demonstrates a special effect of the present invention.

Example 1:

casting was carried out using the apparatus shown in FIG. 3A, the diameter of the stainless steel wire was 0.1mm, and TiO was coated on the wire to a thickness of 10 μm by PVD₂Having the component Zr₅₅Al₁₀Ni₅Cu₃₀Alloy made of metal by melting related components in degree of vacuum of 1.33X 10^-2Casting under vacuum of Pa. The metal mold used had a cylindrical cavity with a diameter of 2.5mm and a length of 10.5 mm. After casting, the cast product was taken out of the mold, and a wire was pulled out of the product at a speed of 1.7 mm/sec to form a small hole. In this step, the tensile load is 294N/mm². The formed small holes had a shape of a circular cross section of a stainless steel wire as observed with a microscope.

Example 2

Casting was carried out using a metal mold similar to that used in example 1, the diameter of the titanium alloy wire was 0.1mm, and an oxide film of 5 μm thickness was formed on the surface thereof by oxidation. The pull-out load was 98N/mm². According to the formed pinholes observed with a microscope, it was confirmed that the formed pinholes had a circular sectional shape of the titanium alloy wire.

Example 3

A wire of 45Ni-55Ti superelastic alloy, having a diameter of 0.1mm and an oxide film of 4 μm thickness formed on the surface thereof, was cast in the same manner as described above. The pull-out load was 785N/mm². According to the formed pores observed with a microscope, it was confirmed that the formed pores had a circular sectional shape of a line.

While these examples of operation are disclosed, the present invention may be embodied in other specific forms without departing from its spirit or characteristics. For example, the method described above uses a metal mold having one cavity to produce a cast product in a simple manner, but the present invention may use a metal mold having two or more cavities to produce two or more cast products. The invention is not limited to the embodiments of the mold size, shape and number of cavities described above, nor to the examples of applications described above, which are intended to be illustrative only and not limiting. The scope of the invention is indicated by the appended claims, rather than the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. A method of producing a cast product having small holes, comprising the steps of: placing a linear core member having a desired sectional shape in a metal mold cavity, injecting molten metal into said metal mold cavity to produce a cast product, pulling out said linear core member from said cast product to form a small hole having a sectional shape of said linear core member,

the method is characterized in that: a linear core member having a surface film formed by surface coating or surface treatment is used as the above linear core member, and the linear core member is pulled out from the cast product after casting, thereby forming a small hole substantially equal to the sectional shape of the linear core member in the cast product.

2. The method according to claim 1, wherein said linear core member is formed such that when the linear core member is pulled out from the cast product after casting, a part or all of said surface film is peeled off from said linear core member, thereby pulling said linear core member out from the cast product.

3. The method according to claim 1, wherein said surface film of said linear core member is an oxide film, a nitride film or a carbide film comprising said linear core member.

4. A method according to any one of claims 1 to 3, wherein said linear core member is made of a titanium-based alloy.

5. A method according to any one of claims 1 to 3, wherein said surface film of said linear core member has a thickness in the range of 0.5 μm to 100 μm.

6. A method according to any one of claims 1 to 3, wherein said linear core has a diameter in the range 0.025mm to 1 mm.

7. A method according to any one of claims 1 to 3, wherein a tensile load in a drawing direction is applied to said linear core member provided in said mold when the molten metal is injected into said mold cavity.

8. A method according to claim 7, wherein said tensile load is no greater than 1960N/mm²。

9. A method according to any one of claims 1 to 3, wherein said cast material is an alloy containing at least 50% by volume of an amorphous phase.

10. The method according to claim 9, wherein said alloy is a substantially amorphous alloy whose composition is represented by one of the following general formulae (1) to (6):

M¹ _aM² _bLn_cM³ _dM⁴ _eM⁵ _f …(1)

wherein: m¹Represents one of two elements Zr and Hf; m²Represents at least one element selected from the group consisting of: ni, Cu, Fe, Co, Mn, Nb, Ti, V, Cr, Zn, Al and Ga; ln represents at least one element selected from the group consisting of: y, La, Ce, Nd, Sm, Gd, Tb, Dy, Ho, Yb and Mm (Mish metal: aggregate of rare earth elements); m³Represents at least one element selected from the group consisting of: be, B, C, N and O; m⁴Represents at least one element selected from the group consisting of: ta, W and Wo; m⁵Represents at least one element selected from the group consisting of: au, Pt, Pd and Ag; a, b, c, d, e and f represent atomic percentages which satisfy, respectively: a is more than or equal to 25 and less than or equal to 85, b is more than or equal to 15 and less than or equal to 75, c is more than or equal to 0 and less than or equal to 30, d is more than or equal to 0 and less than or equal to 30, e is more than or equal to 0 and less than or equal to 15, and f is more than or equal to,

Al_100-g-h-iLn_gM⁶ _nM³ _i …(2)

wherein: ln represents at least one element selected from the group consisting of: y, La, Ce, Nd, Sm, Gd, Tb, Dy, Ho, Yb and Mm; m⁶Represents at least one element selected from the group consisting of: ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Hf, Ta and W; m³Represents at least one element selected from the group consisting of: be, B, C, N and O; g, h and i represent atomic percentages which respectively satisfy: g is more than or equal to 30 and less than or equal to 90, h is more than or equal to 0 and less than or equal to 55, and i is more than or equal to 0 and less than or equal to 10,

Mg_100-pM⁷ _p …(3)

wherein: m⁷Represents at least one element selected from the group consisting of: cu, Ni, Sn and Zn; p represents atomic percent, ranging from: p is more than or equal to 5 and less than or equal to 60,

Mg_100-q-rM⁷ _qM⁸ _r …(4)

wherein: m⁷Represents at least one element selected from the group consisting of: cu, Ni, Sn and Zn; m⁸Represents at least one element selected from the group consisting of: al, Si and Ca; g and r represent atomic percentages satisfying 1. ltoreq. q.ltoreq.35 and 1. ltoreq. r.ltoreq.25, respectively,

Mg_100-q-sM⁷ _qM⁹ _s …(5)

wherein: m⁷Represents at least one element selected from the group consisting of: cu, Ni, Sn and Zn; m⁹Represents at least one element selected from the group consisting of: y, La, Ce, Nd, Sm and Mm; q and s represent atomic percentages satisfying 1. ltoreq. q.ltoreq.35 and 3. ltoreq. s.ltoreq.25, respectively; and

Mg_100-q-r-sM⁷ _qM⁸ _rM⁹ _s …(6)

wherein: m⁷Represents at least one element selected from the group consisting of: cu, Ni, Sn and Zn; m⁸Represents at least one element selected from the group consisting of: al, Si and Ca; m⁹Represents at least one element selected from the group consisting of: y, La, Ce, Nd, Sm and Mm; q, r and s represent atomic percentages which satisfy, respectively: q is more than or equal to 1 and less than or equal to 35, r is more than or equal to 1 and less than or equal to 25, and s is more than or equal to 3 and less than or equal to 25.

11. A method according to any one of claims 1 to 3, wherein said casting material is a die-cast alloy selected from the group consisting of: al-based alloys, Mg-based alloys, Zn-based alloys, Fe-based alloys, Cu-based alloys, and titanium alloys.

12. A method according to any one of claims 1 to 3, wherein said cast article is an optical connector member for inserting or fixing an optical fiber.

13. A method of producing a cast product having small holes, comprising the steps of: placing a linear core member having a desired sectional shape in a metal mold cavity, injecting molten metal into the mold cavity to produce a cast product, pulling out the linear core member from the cast product to form a small hole having a sectional shape of the linear core member,

the method is characterized in that: the linear core member is configured such that, when the linear core member is pulled out from a cast product after casting, the linear core member is elastically deformed in a pulling-out direction to make a diameter of the linear core member smaller than an original diameter, thereby enabling the linear core member to be pulled out from the cast product.

14. The method of claim 13, wherein said linear core member is made of a Ni-Ti superalloy.

15. A method according to claim 13 or 14, wherein the diameter of said linear core is in the range 0.025mm to 1 mm.

16. A method according to claim 13 or 14, wherein a tensile load in a drawing direction is applied to said linear core member provided in said mold while the molten metal is injected into said mold cavity.

17. A method according to claim 16, wherein said tensile load is no greater than 1960N/mm²。

18. A method according to claim 13 or 14, wherein said cast material is an alloy containing at least 50% by volume of an amorphous phase.

19. The method according to claim 18, wherein said alloy is a substantially amorphous alloy whose composition is represented by one of the following general formulae (1) to (6):

M¹ _aM² _bLn_cM³ _dM⁴ _eM⁵ _f …(1)

wherein: m¹Represents one of two elements Zr and Hf; m²Representative is selected from the groupAt least one element selected from: ni, Cu, Fe, Co, Mn, Nb, Ti, V, Cr, Zn, Al and Ga; ln represents at least one element selected from the group consisting of: y, La, Ce, Nd, Sm, Gd, Tb, Dy, Ho, Yb and Mm (Mish metal: aggregate of rare earth elements); m³Represents at least one element selected from the group consisting of: be, B, C, N and O; m⁴Represents at least one element selected from the group consisting of: ta, W and Wo; m⁵Represents at least one element selected from the group consisting of: au, Pt, Pd and Ag; a, b, c, d, e and f represent atomic percentages which satisfy, respectively: a is more than or equal to 25 and less than or equal to 85, b is more than or equal to 15 and less than or equal to 75, c is more than or equal to 0 and less than or equal to 30, d is more than or equal to 0 and less than or equal to 30, e is more than or equal to 0 and less than or equal to 15, and f is more than or equal to,

Al_100-g-h-iLn_gM⁶ _nM³ _i …(2)

wherein: ln represents at least one element selected from the group consisting of: y, La, Ce, Nd, Sm, Gd, Tb, Dy, Ho, Yb and Mm; m⁶Represents at least one element selected from the group consisting of: ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Hf, and W; m³Represents at least one element selected from the group consisting of: be, B, C, N and O; g, h and i represent atomic percentages which respectively satisfy: g is more than or equal to 30 and less than or equal to 90, h is more than or equal to 0 and less than or equal to 55, and i is more than or equal to 0 and less than or equal to 10,

Mg_100-pM⁷ _p …(3)

Mg_100-q-rM⁷ _qM⁸ _r …(4)

Mg_100-q-sM⁷ _qM⁹ _s …(5)

wherein: m⁷Represents selected from the group consisting ofOne element is reduced: cu, Ni, Sn and Zn; m⁹Represents at least one element selected from the group consisting of: y, La, Ce, Nd, Sm and Mm; q and s represent atomic percentages satisfying 1. ltoreq. q.ltoreq.35 and 3. ltoreq. s.ltoreq.25, respectively; and

Mg_100-q-r-sM⁷ _qM⁸ _rM⁹ _s …(6)

20. The method according to claim 13 or 14, wherein said casting material is a die-cast alloy selected from the group consisting of: al-based alloys, Mg-based alloys, Zn-based alloys, Fe-based alloys, Cu-based alloys, and titanium alloys.

21. A method according to claim 13 or 14, wherein said cast article is an optical connector member for inserting or fixing an optical fiber.

22. An apparatus for producing a cast product having a pinhole, comprising a metal mold having a cavity defining an outer shape of the product, characterized in that: a movable cylindrical guide having a central bore is slidably disposed in said mold so as to be extendable into and retractable from the mold cavity, and a linear core member disposed in said mold passes through the central bore of said cylindrical guide.

23. The apparatus of claim 22, further comprising a diameter of no more than 1960N/mm²Is applied to the longitudinal direction of the linear core.