JP7420353B2 - Manufacturing method for perforated castings - Google Patents

Description

The present invention relates to a perforated cast product of metal or semiconductor material that can be effectively used as a new material in various fields such as heat sinks, aircraft engine turbines, medical instruments, machine tools, thermoelectric conversion materials, etc., and a method for manufacturing the same.

Porous metal materials and foamed metal materials have low density and large surface area, and are expected to be mainly used as lightweight materials, catalysts, electrodes, vibration absorbers, sound absorbers, and shock absorbers. A lotus metal molded body is known as one of the porous metal materials. A lotus metal molded body is a metal molded body that is produced by a known method such as a pressurized gas method or a thermal decomposition method, and has pores extending in one direction (for example, Patent Document 1 reference.). By cutting this into a plurality of plates, a porous metal plate (lotus metal plate) having a large number of through holes can be obtained. Lotus metal plates have excellent heat transfer properties, and have been proposed for use as heat sinks for electronic devices and various heat exchange fins (see, for example, Patent Documents 2 and 3).

However, since there is a limit to the length of the pores in the lotus metal molded body, there is a limit to the thickness of the lotus metal plate after cutting, since the holes in the lotus metal plate are made into through holes. In order to ensure even better cooling performance as a fin for a heat sink or the like, it is desirable to form long holes. The ability to form long pores is also advantageous when applied to the above-mentioned catalysts, electrodes, vibration absorbers, sound absorbers, and shock absorbers.

Other methods for producing porous metal materials include a method in which the holes are mechanically drilled in post-processing, and a method in which the holes are formed by melting and vaporizing the metal using an electron beam or laser. However, the smaller the hole, the more likely the drill will break, the longer the machining time, the higher the cost, and the length of the hole is limited by the length of the drill tool. Electron beams require high-vacuum equipment, are expensive, and are unsuitable for industrialization. Laser processing is possible even in the atmosphere, but drilling requires a great deal of expense and time. Further, even when processing with an electron beam or laser, the ratio of the length to the diameter of the hole (aspect ratio) is about 10 at most, and there is a limit to the ability to make long, thin holes.

Furthermore, all of the conventional porous metal materials described above could only have linear pores extending in one direction. This is because the Lotus metal molded body uses unidirectional solidification in its manufacturing method, and drilling, electron beam processing, etc. are also linear drilling processes. If thinner, longer, and curved holes could be made, the degree of freedom in design would be greatly improved for the above-mentioned heat sinks and other applications, and it would be possible to provide a base material with excellent performance. can.

Patent No. 4217865 JP2018-73869A Japanese Patent Application Publication No. 2018-179412

Therefore, the present invention aims to solve the above-mentioned situation by making it possible to provide a porous metal material with longer, thinner, and curved holes at a lower cost, and to improve the overall shape. The dimensions and the shape and dimensions of the holes can be freely set as appropriate, dramatically increasing the degree of freedom in design. The object of the present invention is to provide a porous metal material that can be provided at a low cost and with higher performance when used as a sound absorbing material, a shock absorbing material, etc., and a method for producing the same.

The present invention includes the following inventions.
(1) A perforated cast product made of metal or semiconductor material, characterized by having one or more heat-resistant wire drawing holes opened on its surface.

(2) The perforated casting product according to (1), wherein the heat-resistant wire drawing hole is a through hole.

(3) The hole according to (1) or (2), wherein the heat-resistant wire drawing hole is linear, curved (e.g., wavy, spiral, etc.), or bent (bent in multiple directions). Cast products.
(4) The perforated casting according to any one of (1) to (3), wherein the hole size (diameter) of the heat-resistant wire drawing hole is 100 μm to 20 mm, preferably 200 μm to 10 mm, more preferably 300 μm to 5 mm. Goods.
(5) The hole according to any one of (1) to (4), wherein the length of the heat-resistant wire drawing hole is 1 mm to 2000 mm, preferably 5 mm to 1000 mm, and more preferably 10 mm to 300 mm. Cast products.
(6) The perforated casting according to any one of (1) to (5), wherein the heat-resistant wire drawing hole has an aspect ratio of 0.05 to 20,000, preferably 1 to 1,000, more preferably 3 to 800. Goods.

(7) The perforated cast product according to any one of (1) to (6), which is a cast product of aluminum or aluminum alloy metal or semiconductor material.

(8) One or more heat-resistant wires are provided in the mold, and after the molten metal or semiconductor material is supplied and solidified, the heat-resistant wires are pulled out to open one or more heat-resistant wire drawing holes on the surface. A method for producing a perforated cast product, the method comprising obtaining a cast product of a metal or semiconductor material.

(9) The method for producing a perforated cast product according to (8), wherein the surface of the heat-resistant wire is coated with a mold release agent in advance at the latest before supplying the molten metal or semiconductor material.

(10) The method for manufacturing a perforated cast product according to (8) or (9), wherein the heat-resistant wire is a thin metal wire having a predetermined shape retention property and bending deformability.

(11) After the solidification and demolding, the heat-resistant wire is pulled out of the cast product of the metal or semiconductor material, thereby producing a cast product of the metal or semiconductor material in which one or more heat-resistant wire drawing holes are opened on the surface. The method for producing a perforated cast product according to any one of (8) to (10).

(12) The production of the perforated cast product according to any one of (8) to (10), wherein the heat-resistant wire is integrally provided with the mold, and when demolding, the heat-resistant wire is pulled out together with the mold. Method.

(13) The heat-resistant wire is linear, curved (for example, wavy, spiral, etc.), or bent (bent in multiple directions), and if it is curved or bent, it is deformed by bending. The method for producing a perforated cast product according to (10), wherein the heat-resistant wire drawing hole is obtained in a straight, curved, or bent shape by the drawing.

According to the present invention as described above, a perforated cast product can be obtained by drawing a heat-resistant wire, so such a perforated cast product can be used as a cut product of a lotus metal molding, a drill, an electron beam, a laser, etc. Compared to post-processed products, it is possible to provide products with longer and narrower holes at a lower cost, and it is also possible to create holes that extend in a curved shape, and the overall shape and dimensions also depend on the mold. It can be set freely, and the shape and dimensions of the hole can also be set freely by appropriately setting the length, thickness, shape, etc. of the heat-resistant wire.

Therefore, the degree of freedom in design has been dramatically improved, and it has excellent cooling performance as a heat sink, etc., and it can be used as a catalyst, electrode, vibration absorbing material, sound absorbing material, shock absorbing material, etc. Can be provided at cost. The present inventor has confirmed that a long, narrow hole with an aspect ratio of 786 can be easily provided, as will be described later. It has also been confirmed that curved or polygonal holes can be provided. The diameter of the pores can be approximately 100 μm to 20 mm.

FIG. 1 is a perspective view showing a perforated casting product according to a representative embodiment of the present invention. Explanatory drawing showing another example of a perforated casting product. Explanatory drawing which similarly shows yet another example of a perforated casting product. Explanatory drawing which similarly shows yet another example of a perforated casting product. Explanatory drawing which similarly shows yet another example of a perforated casting product. Explanatory drawing which similarly shows yet another example of a perforated casting product. Explanatory drawing which similarly shows yet another example of a perforated casting product. Explanatory drawing which similarly shows yet another example of a perforated casting product. Explanatory drawing which similarly shows yet another example of a perforated casting product. Explanatory drawing which similarly shows yet another example of a perforated casting product. Explanatory drawing which similarly shows yet another example of a perforated casting product. An explanatory diagram showing an example of the manufacturing procedure of a perforated cast product. Similarly, an explanatory diagram of the manufacturing procedure. Similarly, an explanatory diagram of the manufacturing procedure. Similarly, an explanatory diagram of the manufacturing procedure. Similarly, an explanatory diagram of the manufacturing procedure. Similarly, an explanatory diagram of the manufacturing procedure. Similarly, an explanatory diagram of the manufacturing procedure. Explanatory diagram showing another example of the manufacturing procedure. An explanatory diagram showing a specific example of a heat-resistant wire drawing process (during drawing). FIG. 2 is an explanatory diagram showing the manufacturing equipment and manufacturing procedure used to prepare the samples of the example. An explanatory diagram showing a manufacturing device and a manufacturing procedure. An explanatory diagram showing a manufacturing device and a manufacturing procedure. An explanatory diagram showing a manufacturing device and a manufacturing procedure. A photograph showing the plate mold and heat-resistant wire used in sample production in the example. Three-dimensional images (hereinafter referred to as "X-ray CT images") measured by X-ray computer tomography of a plurality of samples of the prepared examples. X-ray CT image of another sample. X-ray CT image of another sample. Similarly, an X-ray CT image of another sample, and a photograph of the plate mold and heat-resistant wire used to prepare this sample. A photo showing the appearance of other samples, and the heat-resistant wire and tape measure used to prepare the samples. FIG. 7 is an explanatory diagram showing still another example of the perforated cast product according to the present invention. FIG. 7 is an explanatory diagram showing still another example of a perforated cast product according to the present invention. FIG. 7 is an explanatory diagram showing still another example of a perforated cast product according to the present invention. FIG. 3 is an explanatory diagram showing an example in which a predetermined wire rod is inserted into a part of the drawing hole of the perforated casting product according to the present invention. FIG. 7 is an explanatory diagram showing still another example of a perforated cast product according to the present invention. FIG. 7 is an explanatory diagram showing still another example of a perforated cast product according to the present invention.

Next, embodiments of the present invention will be described in detail based on the accompanying drawings.

As shown in FIGS. 1A and 1B, a perforated cast product 1 made of a metal or semiconductor material according to the present invention has one or more heat-resistant wire drawing holes 10 opened on its surface. Various metal or semiconductor materials are possible. Aluminum was used in the samples of the examples described later, but aluminum alloys, copper, magnesium, iron, cobalt, nickel, chromium, zinc, titanium, zirconium, niobium, molybdenum, palladium, silver, gold, cadmium, indium, tin, platinum , tantalum, lead, bismuth, alloys thereof, silicon, germanium, compounds thereof, and various other metals or semiconductor materials can be used. The heat-resistant wire drawing hole 10 is a hole formed by drawing a heat-resistant wire from a solidified casting as described later, and its cross-sectional shape reflects the cross-sectional shape of the heat-resistant wire, and may be triangular, square, pentagonal, or triangular in addition to circular. Polygonal shapes such as hexagons, cross-sectional shapes such as flat plate (rectangular in cross section), L-shape, V-shape, Y-shape, U (katakana) shape, tube-shape (hollow cylindrical shape), and gear-shape are also available. included. It is also possible to form a hole having a threaded inner circumferential surface (the heat-resistant wire has a male thread shape and has a spiral protrusion on the outer circumferential surface, and is pulled out while rotating).

The cross-sectional area (opening area) also directly reflects the cross-sectional area of the heat-resistant wire, making it possible to easily form long, thin holes that are difficult to form using conventional lotus molding, drilling, laser processing, etc. The cross-sectional area does not have to be the same size for all withdrawal holes. In other words, it also includes perforated cast products composed of holes of different sizes. In structural members, the stress concentration when a load is applied changes depending on the size of the holes, so by mixing large and small holes in this way, the stress distribution due to stress concentration can be changed and the stress concentration can be alleviated. It can be controlled or controlled. In particular, when used as a heat sink, the heat transfer coefficient when a refrigerant flows through the holes changes depending on the size of the holes, so the heat generation distribution can be changed by having such large and small holes mixed, and the heat transfer coefficient can be changed or relaxed.

The cross-sectional area of the heat-resistant wire and the drawing hole may not be constant in the axial direction, but may also be non-uniform. As an example, the heat-resistant wire and the drawing hole may be tapered so that the cross-sectional area becomes gradually smaller (larger). By providing a taper, it is possible to create a hole with a sloped diameter, such that the surface side of the perforated cast product has a large diameter and the deeper part or the opening side on the opposite side has a small diameter. Pull out the heat-resistant wire from the side with the larger diameter. This tapered extraction hole can provide focusing or divergence of heat flow, magnetohydrodynamics, electromagnetic waves, sound waves, light waves, and radiation, enabling a variety of applications. When designing a through hole with a constant taper angle, the opening radius on the large diameter side is r ₀ , the opening radius on the other small diameter side is r _f , and the perforated casting is made along the central axis of the drawing hole. If L is the thickness of the hole, and θ is the angle between the extension of the generatrix extending along the central axis direction on the inner peripheral surface of the hole and the center line (taper angle), then tanθ=(r ₀ - r _f )/L The following relationship is obtained, and the inclination of the generating line (taper angle θ) of such a tapered drawing hole is in the range of 0<tan ⁻¹ {(r ₀ −r _f )/L}<(π/2). I will be entering. Such a tapered hole can also be used for focusing a laser beam.

The length of the heat-resistant wire drawing hole 10 is 1 mm to 2000 mm, preferably 5 mm to 1000 mm, and more preferably 10 mm to 300 mm. If the length is longer than 2000 mm, the heat-resistant wire will also be long, the contact area with the casting will increase, and the frictional force during drawing will increase, making it difficult to pull out. The shorter the length, the easier it is to pull out. The hole diameter (diameter) of the heat-resistant wire drawing hole is 100 μm to 20 mm, preferably 200 μm to 10 mm, and more preferably 270 μm to 5 mm. If the pore diameter is smaller than 100 μm, the heat-resistant wire will also become considerably thinner and will be easily damaged during drawing, making manufacturing difficult. When the hole diameter is larger than 20 mm, the contact area between the heat-resistant wire used and the casting increases, the frictional force during drawing increases, and drawing becomes difficult. When a heat-resistant wire with a moderate thickness is used, the drawing hole 10 can be easily formed.

In the sample preparation described below, heat-resistant wires of various thicknesses (diameters) from 0.28 mm to 3.2 mm are immersed in molten aluminum from the top surface of the plate mold to the top of the heat-resistant wire, and the solidified castings are It is possible to make a through hole by pulling it out. That is, it has been confirmed that when a heat-resistant wire with a thickness (diameter) of 0.28 mm is pulled out, a through hole with an inner diameter of 0.28 mm and a length of 220 mm can be formed. Further, the heat-resistant wire drawing hole 10 does not need to be a through hole, and may be a bottomed hole with at least one end open for drawing, as shown in FIGS. 2A and 2B. In addition, by using thin metal wires that have bending deformability in addition to a predetermined shape retention property, curved (wavy or spiral) or folded It is also possible to form a hole extending in a curved manner.

This makes it possible to increase the length of the drawing hole and provide a base material with better performance. In particular, as shown in FIG. 2D, the pull-out holes 10 can be appropriately bent and arranged so as to follow the shape of the cast body, making it possible to efficiently provide a base material with better performance. Such holes cannot be formed by cutting conventional lotus metal moldings, drilling, electron beam processing, or laser processing. As shown in FIGS. 19(a) and 19(b), a combination of a linear extraction hole 10 and a curved (in this example, spiral) extraction hole 10 is also a preferable example. Furthermore, by appropriately setting the arrangement of the heat-resistant wires when casting the perforated casting product 1, it is possible to easily provide a large number of through or non-through holes 10 extending in different directions, as shown in FIGS. 3B and 3C. You can also do it. Such a perforated cast product 1 having multidirectional drawn holes 10 cannot be produced using a lotus metal molded body in which pores are formed in one direction, and drilling, electron beam processing, and laser processing are time-consuming and require equipment. This increases the size and costs. In this way, since the drawing holes can be set in multiple directions, it is possible to suppress stress concentration in the cast product when stress is applied to the cast product, and it is possible to provide a lightweight metal or semiconductor material with sufficient strength.

Furthermore, as shown in FIG. 3D, it is possible to easily form holes that branch in the middle of the interior by using heat-resistant wires that also branch. This also cannot be achieved with a lotus metal molded body, and drilling etc. will also be extremely costly. In this way, since the direction and branching of the through holes can be freely set, a heat sink having a versatile cooling path can be manufactured, and applications in various fields can be expected. Moreover, in addition to completely removing the heat-resistant wire 2 to form a through or non-penetrating hole, the drawing hole (10) of the present invention can be made by pulling out the heat-resistant wire 2 halfway, as shown in FIG. By removing the protruding portion, a part of the heat-resistant wire may remain inside, the remaining side may be closed with the heat-resistant wire, and only the other end may be formed as a pull-out hole that is open. With such a pull-out hole, it is possible to increase the strength of the area where the heat-resistant wire remains, and especially when this perforated casting product 1 is used for the frame of a moving body such as an automobile, the pull-out hole is present. This makes it possible to achieve both weight reduction and strength maintenance (or strength increase). In other words, by mixing the hollow lightweight region from which the heat-resistant wire has been drawn and the remaining strength-enhancing region, it is possible to create a light and strong composite material (due to the holes and the heat-resistant wire), and by setting the drawing direction. The form of the mixture can also be easily changed, providing a high degree of freedom in design.

In addition to leaving a part of the heat-resistant wire in one drawing hole, as shown in FIGS. It is also a preferable embodiment to leave the heat-resistant wire in place, and to make the area where the heat-resistant wire remains not a pull-out hole but a strength-enhancing region filled with the heat-resistant wire. As a result, for example, in long structural members, where a large local load is applied (stress concentration area), the heat-resistant wire can be left in place without being pulled out to increase strength, and in other parts, the heat-resistant wire can be pulled out. By forming holes, it becomes possible to reduce the weight. For example, in the example shown in FIGS. 19(a) and 19(b), part or all of the linear drawing hole 10 is filled with the heat resistant wire without pulling out the heat resistant wire, and the spiral drawing hole 10 is filled with the heat resistant wire without being pulled out. On the contrary, the heat-resistant wire is buried in the spiral drawing hole 10 without pulling out the heat-resistant wire, and the heat-resistant wire is buried in a spiral shape around the straight drawing hole. A preferred example is one that is reinforced with. As another example, as shown in FIG. 18, after producing the perforated casting product of the present invention, a reinforcing wire 8 is inserted into a part of the drawing hole, so that the central part of the elongated structural member is It is also a preferable example to fill and reinforce only the stress concentration part with the reinforcing member (wire rod 8). In this case, both end portions of the member can be made into perforated portions.

The perforated cast product 1 can be manufactured using a mold 3 provided with a heat-resistant wire 2, for example, as shown in FIG. 4A. In the illustrated example, the mold 3 includes a plate-shaped plate mold 30 that forms the bottom surface of the cast product and supports the heat-resistant wire 2 in an upwardly protruding state, and an integrated plate mold 30 and the heat-resistant wire 2. It is configured in combination with a container-shaped outer mold 31 that is placed inside and forms the outer peripheral surface of the cast product. FIG. 4B shows a state in which the plate mold 30 and the heat-resistant wire 2 are set inside the outer mold 31. It is preferable that a supporting recess into which the lower end of the heat-resistant wire 2 is inserted and supported is formed on the upper surface of the plate mold 30.

At least the outer surface of the heat-resistant wire 2 is coated with a mold release agent. In addition to the heat-resistant wire 2, it is preferable that a mold release agent is also applied to the upper surface of the plate mold 30 and the inner peripheral surface of the outer mold 31. The timing of applying the mold release agent is that the mold release agent may be applied to the entire integrated plate mold 30 and heat-resistant wire 2 in advance, and then set in the outer mold 31 after drying, or it may be applied after the mold is set. You can also do it.

As the mold release agent, various known mold release agents can be used depending on the metal or semiconductor material used. Specifically, metals or semiconductors that use known mold release agents mainly containing boron nitride, alumina (alumina cement), graphite, fullerene, silicon, molybdenum disulfide, chromium oxide, etc. Can be selected depending on the material. For example, in the case of aluminum and magnesium, a mold release agent based on boron nitride is preferable, while in the case of copper, iron, steel, stainless steel, nickel, gold, silver, platinum, silicon, germanium, and many other semiconductor materials. It is preferable to use a mold release agent containing alumina as a main component. Furthermore, the mold release agent must be selected so that the maximum temperature at which it can retain its mold release function is higher than the melting point of the metal or semiconductor material used. In order to improve the wettability and adhesion between the mold release agent and the surface of the heat-resistant wire, an organic solvent or the like may be added to the main component for mold release. However, if the organic solvent causes a reaction with the molten material and reduces the mold release functionality, the main mold release material alone can be applied to the heat-resistant wire.

Then, while heating the mold 3 (outer mold 31) as appropriate, as shown in FIG. After pouring the metal into the mold 3 in which the metal is erected, it is cooled and solidified in the state shown in FIG. 5B. The molten material fills the gap between the heat-resistant wires 2 and solidifies into a state integrated with the heat-resistant wires 2. The molten material may be supplied by setting a solid metal or semiconductor material (solid material) on the upper part of the mold, melting it by heating, and moving it into the mold below.

If the heat resistant wire 2 is poured until it is completely buried, the hole for drawing the heat resistant wire becomes a non-penetrating hole, and if the pouring is stopped when the upper end of the heat resistant wire 2 protrudes from the surface of the molten metal, the heat resistant wire can be pulled out. The hole becomes a through hole. In this way, the penetration/non-penetration of the drawing hole can be set by the length of the heat-resistant wire or the amount of poured metal. If the distance between the heat-resistant wires 2 is small, the immersion of the molten material may be insufficient due to surface tension or viscosity. It is preferable to provide one.

After the molten material has solidified, as shown in FIG. 6A, the plate mold 30 is separated from the outer mold 31 by pushing it up from below with a pin (not shown), and the molded metal or semiconductor material is made integral with the heat-resistant wire 2. The plate mold 30 with 4 placed on the upper surface side is taken out. Here, it is of course possible to make the side wall and the bottom wall of the outer mold 31 separable so that the bottom wall can be removed and taken out from the bottom side.

Then, as shown in FIG. 6B, while the side surface 4b of the casting 4 is held and supported by the jig 5, the plate mold 30 on the lower surface side is removed, and the lower end of each heat-resistant wire 2 is exposed (protruded). As shown in FIG. 6C, the portion 2a is pinched using a clamping jig 6 or the like and pulled out downward, thereby forming a pull-out hole 10 in the casting 4 and completing the perforated casting 1. When the lower end portion 2a is pulled out, the lower end portion 2a is exposed by protruding by the depth of the supporting recess. If the heat-resistant wire 2 is also exposed above to form a through hole, the heat-resistant wire 2 can be pulled upward from the upper end.

FIG. 8 shows an example of the jigs 5 and 6. In this example, while the side surface 4b of the casting 4 is fixed with a vise (jig 5), the exposed lower end 2a of the heat-resistant wire 2 embedded in the casting 4 is held with a collet chuck (jig 6). Multiple pieces are pulled out at the same time. More specifically, a multi-core collet chuck is used as the jig 6, and as shown in the figure, the lower end portions 2a of the plurality of heat-resistant wires 2 are gripped and moved downward, thereby simultaneously holding the plurality of heat-resistant wires 2. This is a preferable example. The collet chuck jig 6 can freely move vertically and horizontally, grips the heat-resistant wire 2, and performs the work of pulling out the heat-resistant wire 2.

In this example, as shown in FIGS. 6B and 6C, after removing the plate mold 30 from the casting 4, the heat-resistant wire 2 is pulled out using the jig 6. In terms of efficiency, it is also preferable for the heat-resistant wire 2 to be firmly fixed so that when the plate mold 30 is removed, the heat-resistant wire 2 also moves downward together with the plate mold 30 and is pulled out. That is, the heat-resistant wire can be pulled out from the casting after demolding, or the heat-resistant wire can be provided integrally with the mold so that the heat-resistant wire can be pulled out together with the mold during demolding.

In the example of the manufacturing apparatus shown in FIGS. 9A to 9D, as shown in FIG. 9A, a plate mold 30 and a heat-resistant wire 2 that are firmly fixed to each other are set in a crucible-shaped outer mold 31, and inside the outer mold 31. By inserting a solid metal or semiconductor material (solid material 9) into the upper part of the heat-resistant wire 2 and heating it with the heater 7, the solid material 9 is melted as shown in FIG. 9B, and the molten material is transferred to the heat-resistant wire 2. This is an example of filling and solidifying the gap between the particles. Then, as shown in FIG. 9C, the plate mold 30 with the metal or semiconductor material casting 4 integrated with the heat-resistant wire 2 placed on the upper surface side is taken out from the outer mold 31, and then the plate mold 30 is removed from the outer mold 31 as shown in FIG. 9D. By separating the mold 30 from the casting 4, the heat-resistant wire 2 is simultaneously pulled out together with the plate mold 30, and a perforated casting can be efficiently obtained.

In the above example, the heat-resistant wire is arranged in the vertical direction and the drawing holes are formed in the vertical direction, but it is of course possible to form the holes in the horizontal direction. In that case, for example, as shown in FIG. 7, a pair of left and right plate molds 30 is provided, which are also set in the outer mold 31, and the pouring, solidification, removal of the plate mold 30, and drawing of the heat-resistant wire 2 are performed in the same manner. Can be manufactured. In this case, the plate mold 30 forms the side surface of the casting of metal or semiconductor material, and the outer mold 31 forms the bottom surface.

The heat-resistant wire has a predetermined shape retention property and bending deformability, and preferably a thin metal wire is used. In addition to being linear as in this example, the heat-resistant wire 2 can be curved (e.g., wavy, spiral, etc.) or bent (bent in multiple directions), and can be left in this shape. The heat-resistant wire drawing hole 10 having a curved or bent shape can be obtained by drawing out the heat-resistant wire from a casting integrated with a metal material while bending and deforming it. Since the heat-resistant wire must maintain heat resistance when molten material is poured into it, its melting point must be higher than the melting point of the metal or semiconductor material used for the molten material. It is desirable that the temperature be at least 100°C higher.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way, and it goes without saying that the present invention can be implemented in various forms without departing from the gist of the present invention.

A plurality of samples according to the embodiment of the perforated casting product of the present invention were manufactured using the manufacturing apparatus consisting of the crucible shown in Fig. 9, but the plate and the heat-resistant wire were not firmly fixed, and the appearance of the drawn holes was We will explain the results of our observations.

(Preparation of sample)
As the heat-resistant wires that serve as templates for the holes to be formed, multiple types of stainless steel (SUS) wires, copper wires, platinum wires, and molybdenum wires with different thicknesses were prepared. The thicknesses of the stainless steel wires were 0.28 mm, 0.35 mm, 0.45 mm, 0.7 mm, 0.85 mm, 1.2 mm, 1.6 mm, 2.0 mm, and 3.2 mm. The thicknesses of the copper wire, platinum wire, and molybdenum wire were 1.0 mm, 0.6 mm, and 1.0 mm, respectively.

Each heat-resistant wire was attached to the upper surface of a plate mold consisting of a cylindrical graphite disk that forms the bottom surface of the cast product in a state in which it protruded upward, and a release agent was applied to the entire plate mold and heat-resistant wire. . FIG. 10 shows an example of a heat-resistant wire and plate mold coated with a mold release agent. The heat-resistant wire in Fig. 10(a) is a stainless steel (SUS304) wire with an outer diameter of 0.85 mm, and nine wires are provided with each protruding by approximately 25 mm, and the heat-resistant wire in Fig. 10(b) is , seven stainless steel (SUS304) wires with an outer diameter of 3.2 mm, each protruding by about 25 mm.

In this way, the heat-resistant wire and plate mold were inserted and set in a cylindrical graphite crucible mold (inner diameter 15 mm) forming the outer peripheral surface of the cast product, with the heat-resistant wire facing upward. "BN Coat <M>" (manufactured by Odec Co., Ltd.) made of boron nitride was used as a mold release agent. The coating thickness of the mold release agent was 10 to 20 μm. Inside this crucible mold, a predetermined amount of solid aluminum (99.99% purity) is placed as a solid material so as to be in contact with the upper end of the heat-resistant wire, and the entire crucible mold is placed in a vertical electric furnace. The aluminum was melted by holding at 953K for 360 seconds, and the molten aluminum was dropped between the heat-resistant wires to fill the voids between the heat-resistant wires. After heating for 360 seconds, the crucible mold was taken out from the vertical electric furnace and cooled to solidify the aluminum inside.

After taking out the aluminum casting that has solidified integrally with the heat-resistant wire and plate mold from the crucible mold, the plate mold and heat-resistant wire are pulled out from the casting, and the aluminum casting with a plurality of penetrating heat-resistant wire drawing holes opened on the surface is made. I got the item. More specifically, the pulling was performed by first removing the plate mold, and then pulling out the heat-resistant wires one by one with pliers.

(observation results)
Three-dimensional images of the produced porous aluminum castings were measured using X-ray computer tomography. The X-ray tube voltage is 200 kV and the current is 250 μA. 11 to 14 show X-ray CT images of each sample, and FIG. 15 shows an external photograph. In Fig. 11(a), the heat-resistant wires are nine stainless steel (SUS304) wires with an outer diameter of 0.28 mm, and in (b), the heat-resistant wires are nine stainless steel (SUS304) wires with an outer diameter of 0.35 mm. , (c) uses 9 stainless steel (SUS304) wires with an outer diameter of 0.45 mm as heat-resistant wires, and (d) uses 21 stainless steel (SUS304) wires with an outer diameter of 0.70 mm as heat-resistant wires, ( In e), 9 stainless steel (SUS304) wires with an outer diameter of 0.85 mm are used as heat-resistant wires, in (f), 21 stainless steel (SUS304) wires with an outer diameter of 1.2 mm are used as heat-resistant wires, and in (g) (h) is nine stainless steel (SUS304) wires with an outer diameter of 1.6 mm as heat-resistant wires, (h) is nine stainless steel (SUS304) wires with an outer diameter of 2.0 mm as heat-resistant wires, and (i) is Seven stainless steel (SUS304) wires with an outer diameter of 3.2 mm were used as heat-resistant wires.

The manufactured sample had a cylindrical shape with an outer diameter of 15 mm reflecting the shape of the inner peripheral surface of the crucible, and as can be seen from FIG. 11, a plurality of heat-resistant wire drawing holes extending in the axial direction can be confirmed. Furthermore, a casting defect (shrinkage cavity) was observed in the upper center of the cast product, and many small spherical images were also observed. These are defects created on the surface of the casting. This is formed during the solidification process, but since the heat-resistant wire is present in the heat-resistant wire drawing hole during solidification, defects such as hole clogging do not occur, and the hole space can be reliably secured. The aspect ratio can be determined from the ratio of the length to the inner diameter of the heat-resistant wire drawing hole. In the example shown in FIG. 12(a), a stainless steel (SUS304) wire with an outer diameter of 0.85 mm and a length of 25 mm or more was used as the heat-resistant wire, and a drawn hole with an aspect ratio of 29.4 was obtained. In the example shown in FIG. 12(b), a stainless steel (SUS304) wire with an outer diameter of 0.28 mm and a length of 76 mm or more was used as the heat-resistant wire, and a drawn hole with an aspect ratio of 271.4 was obtained. In the example shown in FIG. 12(c), a stainless steel (SUS304) wire with an outer diameter of 0.85 mm and a length of 90 mm or more was used as the heat-resistant wire, and a drawn hole with an aspect ratio of 105.9 was obtained. Further, in the example shown in FIG. 15, a stainless steel (SUS304) wire (only one wire) having an outer diameter of 0.28 mm and a length of 220 mm or more was used as the heat-resistant wire, and a drawn hole with an aspect ratio of 786 was obtained. In this way, the aspect ratio of the sample shown in FIG. 15 was confirmed to be 786 at maximum.

Fig. 13(a) shows an example in which stainless steel wire (outer diameter 0.85 mm) is used as the heat-resistant wire, and Fig. 13(b) shows an example in which copper wire (outer diameter 1.0 mm) and platinum wire (outer diameter 0.6 mm) are used. ) and a heat-resistant wire made of molybdenum wire (outer diameter 1.0 mm) are combined. If interdiffusion occurs between the molten aluminum and the refractory wire, the thickness of the alloy layer formed by the interdiffusion can be estimated from the diffusion data. The mutual diffusion coefficient D _R can be evaluated using the following equation (1).
D _R = c _{Al DM} + c _M D _Al ... (1)
Here, c and D are the composition and intrinsic diffusion coefficient, respectively. The subscripts Al and M represent aluminum and heat-resistant wire metal, respectively.

The diffusion coefficient in molten metal just above the melting point is on the order of 10 ⁻⁹ m ² /s, several orders of magnitude larger than the diffusion coefficient in solid metal. Therefore, 10 ⁻¹⁰ m ² /s≦D _R ≦10 ⁻⁹ m ² /s. The diffusion distance for 360 seconds (time t) can be evaluated as 0.4 mm≦2×(Dt) ^1/2 ≦1.2 mm. When an alloy layer of such thickness is formed between the heat-resistant wire and aluminum, it becomes difficult to pull out the heat-resistant wire, but in this example, as shown in Figure 13, the heat-resistant wire of any metal can be pulled out smoothly. I was able to pull it out. This indicates that the mold release agent was present at the interface between the heat-resistant wire and aluminum, suppressing the formation of an alloy layer due to mutual diffusion.

FIGS. 14(a) to 14(c) are examples in which through holes are provided with spiral or V-shaped extraction holes. The lower columns of FIGS. 14(a) to 14(c) are photographs of the external shapes of the heat-resistant wire and plate mold used in the production of the upper column, respectively. This curved hole morphology is unique to the fabrication method of the present invention. In conventional porous metal materials, Lotus uses unidirectional solidification, and drills and electron beams also perform linear drilling processes, so they can only create straight holes that extend in one direction. On the other hand, it can be seen that the present invention can produce not only straight holes but also curved holes.

1 Perforated casting product 2 Heat-resistant wire 2a End portion 3 Mold 4 Casting 4b Side surface 5 Jig 6 Jig 7 Heater 8 Wire rod 10 Drawing hole 30 Plate mold 31 Outside mold 9 Solid material

Claims (2)

One or more heat-resistant wires, which are thin metal wires with predetermined shape retention and bending deformability, are arranged in a mold in a curved or bent state,
After supplying and solidifying the molten metal or semiconductor material,
By pulling out the heat-resistant wire, which is integrated with the metal or semiconductor material while maintaining the curved or bent shape, from a casting formed by solidifying the metal or semiconductor material while bending and deforming it, the curved shape is obtained. Or a method for manufacturing a perforated casting product, which obtains a casting product of a metal or semiconductor material in which one or more heat-resistant wire drawing holes extending in a bent shape are opened on the surface,
A method for manufacturing a perforated cast product, comprising coating the surface of the heat-resistant wire with a mold release agent in advance at the latest before supplying the molten metal or semiconductor material. The method for manufacturing a perforated cast product according to claim 1, wherein the curved shape is wavy.

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