JP6829373B2 - Manufacturing method of porous structure - Google Patents

Description

The present invention relates to a manufacturing intermediate for a porous structure and a method for manufacturing a porous structure.

A porous metal having a large number of pores formed inside is known, and a porous metal called a lotus metal or the like formed so as to align the pores existing inside in one direction is known. Has been done. Since this porous metal is formed so that the pores are aligned in one direction, it is expected as a structural material for automobiles and aircraft, for example, from the viewpoint of light weight and high rigidity. Porous metal is also attracting attention as a heat insulating material and a sound absorbing material.

As a method for producing a porous metal, a method for producing Patent Document 1 using a floating zone melting method is known. In the production method of Patent Document 1, the rod-shaped metal is continuously moved in a gas atmosphere such as hydrogen. A heating means is provided on the upstream side in the moving direction of the rod-shaped metal, and a cooling means is provided on the downstream side to partially sequentially heat and melt the rod-shaped metal and then sequentially cool and solidify the rod-shaped metal. As a result, after the gas is dissolved in the molten portion of the rod-shaped metal, the molten portion in which the gas is dissolved is solidified, and bubbles are generated due to the difference in the solubility of the gas. Then, by moving the cooling position, the generated bubbles are grown in the moving direction of the cooling position, and directional pores extending in one direction are formed in the rod-shaped metal.

On the other hand, the applicant has proposed in Patent Document 2 a method for producing a porous structure containing a porous metal using a pipe. In the production method of Patent Document 2, for example, the pipe is immersed in the molten metal while preventing the molten metal, which is the base material of the porous metal, from entering the pipe. Then, by solidifying the molten metal in which the pipe is immersed, the outer wall of the pipe and the base material are integrated to produce a porous metal. According to this manufacturing method, since porous metal is manufactured by using the hollow portion of the pipe as directional pores, the size of directional pores in the porous metal (pore length and pore diameter) can be obtained by appropriately changing the inner diameter and arrangement of the pipe. Etc.), the shape of the pores including the cross-sectional shape, the arrangement (the spacing and arrangement of the pores, etc.), and the porosity can be easily obtained.

International Publication No. 03/070401 Japanese Unexamined Patent Publication No. 2013-226594

By the way, in the method for producing a porous metal by the floating zone melting method as in Patent Document 1, pores are formed from bubbles generated by the difference in gas solubility between when the rod-shaped metal is melted and when it is cooled. Therefore, it is difficult to control the size of the pores, the shape and arrangement of the pores, and the porosity. On the other hand, it is easy to control the size of the pores, the cross-sectional shape of the pores, the arrangement, and the porosity in the method of immersing the pipe in the molten metal to form the porous metal as in Patent Document 2. However, since a difference in melting point is required between the base material and the pipe, it is necessary to use different materials for the base material and the pipe. For this reason, the physical properties of the porous metal are affected by the material of the pipe, and for example, the required strength may not be obtained. In addition, a pipe with a large wall thickness is used so as not to be melted, and since it is necessary to leave a space between adjacent pipes, there is a limit to bringing the hollow parts of the pipes that actually become pores close to each other. It was. Therefore, the porosity of the porous metal cannot be sufficiently increased. Further, in the porous metal produced by casting, sufficient strength cannot be obtained unless plastic working is performed, but there is a problem that pores are crushed when plastic working is performed.

The present invention has been made in view of the above circumstances, and is a method for producing an intermediate for producing a porous structure and a method for producing a porous structure, in which directional pores are surely formed and a porous structure having high strength can be easily obtained. The purpose is to provide.

In the present invention, in a method for manufacturing a porous structure having a plurality of directional pores, a rod-shaped member is formed by filling the space around each of the plurality of arranged rod-shaped members with a molten metal of an inorganic material and solidifying the molten metal. An intermediate manufacturing step of obtaining a manufacturing intermediate having a structure portion of an inorganic material in which a plurality of holes are formed in which each of the rod-shaped members is formed, and a plastic working step of plastic working the manufacturing intermediate. It has a removal step of removing a rod-shaped member from a manufacturing intermediate that has undergone a plastic working step.

Further, according to the present invention, in a manufacturing intermediate of a porous structure having a plurality of directional pores, the structure portion formed of an inorganic material and the structure main body portion serving as directional pores are arranged in each hole. It is provided with a rod-shaped member.

According to the method for manufacturing a porous structure of the present invention, the space around a plurality of rod-shaped members is filled with a molten metal of an inorganic material, and then the manufacturing intermediate in which the molten metal is solidified is subjected to plastic working to remove the rod-shaped members. Since a porous structure having directional pores is manufactured, the rod-shaped member prevents the pores that become directional pores from being crushed during plastic working, so that the directional pores are surely formed and high strength is achieved. A porous structure having a structure can be easily obtained.

According to the manufacturing intermediate of the porous structure of the present invention, by applying plastic working to this manufacturing intermediate, crushing of holes that become directional pores during plastic working is prevented, so that this manufacturing intermediate can be used. By using this, a porous structure in which directional pores are surely formed and has high strength can be easily obtained.

It is a perspective view which shows an example of a porous structure. It is explanatory drawing which shows an example of the manufacturing intermediate. It is a flowchart which shows the manufacturing process of a porous structure. It is explanatory drawing explaining the intermediate body manufacturing process. It is explanatory drawing which shows the outline of the processing apparatus which performs plastic working by the ECAE method. It is explanatory drawing which shows the state of the rod-shaped member by the removal process. It is explanatory drawing which shows the example of pouring a hot water after arranging a rod-shaped member in a mold. It is sectional drawing which shows the continuous casting apparatus which continuously manufactures a manufacturing intermediate. It is explanatory drawing which shows the twin-roll casting apparatus which continuously manufactures a manufacturing intermediate by a twin-roll casting method. It is a perspective view which shows the plate-shaped manufacturing intermediate and the porous structure manufactured by the twin roll casting method. It is explanatory drawing which shows the example which manufactures the manufacturing intermediate using a semi-solid slurry. It is explanatory drawing which shows the example of the porous structure in which pores of different diameters are arranged circularly for each diameter. It is explanatory drawing which shows the example of the porous structure which arranged the pores of different diameters in a rectangular shape for each diameter. It is explanatory drawing which shows the example of the porous structure which made the pores the honeycomb arrangement. It is sectional drawing which shows the vertical cross-section of the porous structure which changed the size of the cross-sectional shape of a pore.

In FIG. 1, the porous structure 10 produced in the present embodiment has a plurality of pores 12. Each pore 12 has directionality, that is, a hole extending in a predetermined direction, and is a directional pore. In this example, the porous structure 10 has a cylindrical shape, and each pore 12 extends in the axial direction (X direction) thereof. Each pore 12 is formed as a through hole opened at both ends of the porous structure 10. Further, in this example, the plurality of pores 12 are arranged in a square grid in N rows and M columns (N and M are all integers of 1 or more). Each pore 12 has a circular cross-sectional (cross-sectional) shape perpendicular to the axial direction of the porous structure 10, and its diameter is constant in the axial direction.

The shape of the porous structure 10, the number, arrangement, cross-sectional shape and size of the pores 12 are examples, and these can be made according to the use of the porous structure 10, required characteristics, and the like. .. Further, the porous structure 10 may have one end of the pores 12 closed.

As shown in FIG. 2, the manufacturing intermediate (hereinafter, simply referred to as an intermediate) 14 of the porous structure 10 has a structure portion 15 corresponding to the porous structure 10 and a rod-shaped member 16. The intermediate 14 is produced in the intermediate production step S1 (see FIG. 3) described later. The structure portion 15 has a plurality of holes 17, and the rod-shaped member 16 is contained in the holes 17. After the plastic working step S2 (see FIG. 3), the structure portion 15 from which the rod-shaped member 16 has been removed becomes the porous structure 10, and the holes 17 become the pores 12. In this example, since the porous structure 10 is manufactured from the intermediate 14 without changing the cross-sectional shape, the shapes of the intermediate 14 and the porous structure 10 are the same. Of course, the porous structure 10 may be produced by deforming the intermediate body 14. The rod-shaped member 16 functions as a core for forming the hole 17, and also functions as a crush preventive material for preventing the hole 17 from being crushed in the plastic working step S2.

The method for manufacturing the porous structure 10 will be described below. As shown in FIG. 3, in the manufacturing step S of the porous structure 10, the intermediate manufacturing step S1, the plastic working step S2, and the removing step S3 are performed in this order. The intermediate manufacturing step S1 includes a filling step S1a and a cooling step S1b to prepare an intermediate 14 of the porous structure 10. The plastic working step S2 is a step of performing plastic working on the intermediate body 14 to improve the strength of the porous structure 10. The removing step S3 is a step of removing the rod-shaped member 16 from the intermediate body 14 that has undergone the plastic working step S2 to obtain the porous structure 10.

The filling step S1a of the intermediate body manufacturing step S1 is a step of filling the space around each of the plurality of rod-shaped members 16 with a molten metal in which the material of the porous structure 10 (hereinafter referred to as the structure material) is melted. The cooling step S1b is a step of cooling and solidifying the molten metal around each rod-shaped member 16.

For example, the intermediate manufacturing step S1 is performed using the casting apparatus 20 shown in FIG. The casting apparatus 20 is composed of a mold 21, a holder 22, an elevator 23, and the like. The molten metal 25 in which the structure material is melted is stored in the mold 21. The holder 22 holds the upper ends of the plurality of arranged rod-shaped members 16. The elevator 23 moves the holder 22 between the holding position shown in FIG. 4A and the immersion position shown in FIG. 4B. The holding position is a position where the rod-shaped member 16 held by the holder 22 is separated upward from the liquid level of the molten metal 25 in the mold 21, and the immersion position is a position where the rod-shaped member 16 held by the holder 22 is placed in the mold 21. It is a position to be immersed in the molten metal 25.

In the filling step S1a, as shown in FIG. 4A, a plurality of rod-shaped members 16 are held in a state of being arranged in a square grid of N rows and M columns in the holder 22 at the holding position, and then as shown in FIG. 4B. , The holder 22 is moved to the immersion position, and each rod-shaped member 16 is immersed in the molten metal 25 in the mold 21. As a result, the space around each rod-shaped member 16 including the space between the adjacent rod-shaped members 16 is filled with the molten metal 25. In this example, the lower end surface of the rod-shaped member 16 is brought into close contact with the bottom of the mold 21 to form an intermediate 14 having a through hole 17. When the end portion of the intermediate body 14 is cut off to make the hole 17 a through hole, or when the pore 12 is not made a through hole, the lower end surface of the rod-shaped member 16 may be separated from the bottom portion of the mold 21.

After the filling step S1a, the cooling step S1b is performed. In this cooling step S1b, the molten metal 25 is cooled by the cooler 27 through the mold 21 while the rod-shaped members 16 are immersed in the molten metal 25, and the structural material is solidified. As a result, the structural portion 15 having a plurality of holes 17 is formed, and the intermediate body 14 in which the rod-shaped member 16 is arranged in each hole 17 is obtained. After solidification, the holder 22 is raised to the holding position and the intermediate 14 is taken out from the mold 21. In this way, the intermediate 14 of the porous structure 10 is produced.

The structure material for producing the porous structure 10 is not particularly limited as long as it is an inorganic material that can be in a molten state to fill the space around the rod-shaped member 16 and can be plastically worked. Such an inorganic material may be metal or non-metal. For example, metals such as aluminum, magnesium, titanium, nickel, gold, silver, copper, lead, molybdenum, zinc, and iron, metals mainly composed of these metals, and alloys containing these metal components in a predetermined ratio are used as structural materials. May be good. Further, it may be a structure material containing a non-metal as a main component or a component such as silicon.

In this example, the rod-shaped member 16 has a cylindrical shape having the same diameter as the columnar pores 12 of the porous structure 10. Since the shape of the pore 12 is the same as the shape of the hole 17 and the shape of the hole 17 is the same as the shape of the rod-shaped member 16, a rod-shaped member 16 having the same shape as the desired pore 12 may be used. For example, when forming pores 12 having a rectangular cross-sectional shape, a prismatic member 16 having a rectangular cross-sectional shape may be used. The shape of the rod-shaped member 16 is not particularly limited, and can be a pillar having various cross-sectional shapes such as a polygon, an ellipse, and a star, whereby pores 12 having various shapes can be formed. Further, the shape and size of the cross section may change in the axial direction of the rod-shaped member 16, and the rod-shaped member 16 may have a conical shape or a male screw shape, for example.

The position of the hole 17 of the intermediate body 14 is determined by the position of the rod-shaped member 16 held in the holder 22, and the position of the hole 17 is the position of the pore 12 in the porous structure 10. Therefore, the position of the pore 12 can be controlled by the position of the rod-shaped member 16 held in the holder 22. Then, the arrangement of the rod-shaped members 16 held in the holder 22 is the arrangement of the holes 17 of the intermediate body 14, and in order to determine the arrangement of the pores 12, the arrangement is made according to the desired arrangement of the pores 12. That is, by changing the arrangement of the rod-shaped members 16 held in the holder 22, it is possible to obtain a porous structure 10 having a desired arrangement of the plurality of pores 12, that is, a desired spacing and arrangement of the pores 12. Further, the number of pores 12 can be increased or decreased by increasing or decreasing the number of rod-shaped members 16.

Further, if the distance between the adjacent rod-shaped members 16 is increased or decreased, the distance between the adjacent pores 12 of the porous structure 10 can be increased or decreased accordingly. As a result, the porous structure 10 having a desired density and porosity of the pores 12 can be produced, and the density and porosity of the pores 12 can be freely controlled. For example, by using a cylindrical member 16 having a small diameter and reducing the distance between adjacent rod-shaped members 16, a porous structure 10 having a high density of pores 12 and a high porosity can be produced.

In the conventional method of immersing a hollow pipe in a molten metal to produce a porous structure, it is necessary to use a thick pipe in order to prevent the pipe from being melted and damaged as described above. Further, in this conventional method, in addition to the thickness of the thick wall portion of each adjacent pipe, a gap for the structural material to enter is required between the pipes. As a result, the distance between the pores became large, and it was difficult to increase the density and porosity of the pores. However, in the manufacturing method using the rod-shaped member 16 as in the present embodiment, the rod-shaped member 16 is finally removed and does not become a part of the porous structure 10, so that the distance between the rod-shaped members 16 is reduced. It is possible to densely arrange a large number of rod-shaped members, and a higher density and porosity of the pores 12 are realized.

As the rod-shaped member 16, the rod-shaped member 16 maintains its shape when immersed in the molten metal 25, functions as a crush preventive material for preventing the hole 17 from being crushed in the plastic working step S2, and is formed from the hole 17 in the removing step S3. The rod-shaped member 16 is not particularly limited as long as it can be removed. Regarding the point that the rod-shaped member 16 maintains its shape, it is necessary that the rod-shaped member 16 does not melt or sublimate. Therefore, when the temperature of the molten metal 25 is T and the melting point or sublimation point of the material of the rod-shaped member 16 is Tp, "T <Tp" may be satisfied. When the material of the rod-shaped member 16 is completely melted through the solid-liquid coexisting phase, the solidus temperature is set as the melting point of the material of the rod-shaped member 16.

From the viewpoint of functioning as a crush preventive material, it is preferable to use, for example, a material that is hard to be deformed for the rod-shaped member 16, or to make the rod-shaped member 16 a hard and hard-to-deform structure. In order to remove the rod-shaped member 16 from the hole 17, for example, a material in which the rod-shaped member 16 is brittlely broken can be selected. Further, the material of the rod-shaped member 16 may be a material that is dissolved by, for example, an acid or an alkali. From the viewpoint of not altering or deteriorating the structure material, it is preferable to select a material that does not easily react with the structure material as the material of the rod-shaped member 16.

Examples of the rod-shaped member 16 satisfying the above conditions include those processed into a rod shape using carbon, glass, alumina, or the like.

Following the intermediate manufacturing step S1, the plastic working step S2 is performed. In the plastic working step S2, in order to increase the strength of the porous structure 10, the intermediate 14 obtained in the intermediate manufacturing step S1 is subjected to plastic working. That is, in the plastic working step S2, stress is applied to the intermediate body 14 to plastically deform it, and the intermediate body 14 is work-hardened. As a method of plastic working, well-known processing methods such as forging, rolling, drawing, extrusion, and pressing can be used.

In this example, plastic working is performed by the ECAE (Equal-channel Angular Extrusion) method in which strong strain is applied and work hardening is performed without changing the cross-sectional shape of the intermediate body 14 before and after plastic deformation. In this ECAE method, as shown in FIG. 5, a die 32 is used in which the passage 31 is bent but the cross-sectional dimension of the passage 31 does not change. An intermediate body 14 is inserted into the passage 31 through one opening 31a, the intermediate body 14 is pushed in by a punch 33, and is pushed out through the other opening 31b. As a result, the intermediate body 14 is sheared and deformed at the bent portion of the passage 31 for plastic working. For example, by passing the intermediate body 14 through the passage 31 a plurality of times, high strength is imparted to the structure portion 15 of the intermediate body 14.

Since the plastic working is performed with the rod-shaped member 16 inside the hole 17, the hole 17 does not collapse and retains its original shape even if the structure portion 15 is sheared and deformed. Since the rod-shaped member 16 used to form the hole 17 of the intermediate body 14 is used as a crush-preventing material, plastic working can be efficiently performed, and the rod-shaped member 16 is taken out from the hole 17 and the hole 17 is taken out. There is no need for a process such as inserting a new crush preventive material into the product.

If the ECAE method is used in which the shape of the cross section does not change before and after the plastic deformation of the intermediate body 14 as described above, the holes 17 to be the pores 12 maintain the arrangement before the plastic deformation, the shape and size of the cross section. To do. Therefore, the arrangement of the rod-shaped members 16 and the shape and size of the cross section are the same as the arrangement of the pores 12 in the porous structure 10 and the shape and size of the cross section. Therefore, the pores 12 having a desired arrangement, shape and size It is advantageous in producing the porous structure 10 having the above.

Following the plastic working step S2, the removing step S3 is performed. In this removing step S3, the rod-shaped member 16 is removed from the holes 17 of the intermediate body 14 that has undergone the plastic working step S2. Then, the structure portion 15 from which the rod-shaped member 16 is removed from the hole 17 becomes the porous structure 10. The method for removing the rod-shaped member 16 can be appropriately selected depending on the material of the rod-shaped member 16 and the state of destruction of the rod-shaped member 16 by the plastic working step S2. For example, when the material of the rod-shaped member 16 is a material that is easily brittlely fractured such as carbon, glass, and alumina, for example, as shown in FIG. 6, a rod-shaped instrument 34 having a sharp tip is used as an intermediate 14. The rod-shaped member 16 in the hole 17 can be repeatedly pierced and crushed to remove the rod-shaped member 16. Further, the rod-shaped member 16 may be dissolved and removed with an acid or an alkali. When the rod-shaped member 16 is finely broken by the plastic working step S2, it may be removed by washing the inside of the hole 17 with hot water.

The obtained porous structure 10 is subjected to plastic working as described above, so that the strength is high. The pores 12 of the porous structure 10 are not crushed because the intermediate body 14 in which the rod-shaped member 16 is in the holes 17 is subjected to plastic working, and have a desired shape and size. .. Further, since the intermediate body 14 is plastically processed by the ECAE method, a porous structure 10 in which the pores 12 are formed in the same arrangement as the rod-shaped member 16 can be obtained.

As described above, since the intermediate body 14 in which the rod-shaped member 16 is left in the hole 17 is subjected to plastic working, a step of not crushing the hole 17 such as separately filling the hole 17 with a crush prevention material is performed. It is not necessary, the pores 12 are not crushed, the pores 12 are surely formed, and the porous structure 10 having high strength can be easily obtained.

In the actual experiment, an aluminum alloy (A6061) was used as the structural material and a carbon rod was used as the rod-shaped member to form a cylindrical intermediate, and the intermediate was plastically processed by the ECAE method before carbon. It has been confirmed that when the rod is removed, a porous structure in which the pores are not crushed is obtained. It has also been confirmed that the arrangement, shape, and size of the pores of the porous structure are the same as the arrangement, shape, and size of the carbon rods. It was confirmed that when a porous structure (made of copper) equivalent to an intermediate without a rod-shaped member was subjected to plastic working by the ECAE method, the pores were crushed and the porous structure itself was deformed. ing.

In the above, an example in which the space around the rod-shaped member 16 is filled with the molten metal 25 by immersing the rod-shaped member 16 in the molten metal 25 previously poured into the mold 21 has been described, but the molten metal is filled in the space around the rod-shaped member 16. The method of satisfying 25 is not limited to this. For example, as shown in FIG. 7, after each rod-shaped member 16 is arranged in the mold 21, the molten metal 25 may be poured into the mold 21. In the example shown in FIG. 7, the rod-shaped member 16 is held in an upright state by the holder 36 placed on the bottom of the mold 21. The molten metal 25 may be poured into the mold 21 after the holder 22 holding the rod-shaped member 16 is moved to the immersion position by using the casting apparatus 20 described above. Further, each rod-shaped member 16 may be arranged in the horizontal direction in the mold 21, and the molten metal 25 may be poured into the mold 21.

Next, an example of continuously casting the intermediate will be described. In FIG. 8, the continuous casting apparatus 40 produces a long intermediate 41. The continuous casting apparatus 40 includes a mold 43, a cooling block 44, a crucible 45, a dummy bar 46, and the like. The mold 43 has a tubular shape with both upper and lower ends open. A cooling block 44 is provided on the outer peripheral surface of the mold 43. The cooling block 44 cools the mold 43 by circulating the cooling water supplied from the cooling water circulator 47 inside.

The crucible 45 stores the molten metal 48. The upper end of the mold 43 is fitted in the opening provided on the bottom surface of the crucible 45, and the stored molten metal 48 flows into the mold 43. A heater 51 and a heat insulating material 52 are arranged on the outer periphery of the crucible 45 to maintain the crucible 45 and the molten metal 48 at a predetermined temperature. The dummy bar 46 is initially arranged inside the mold 43 to block the inside of the mold 43. At the time of casting, the dummy bar 46 continuously moves downward inside the mold 43 at a constant speed, and moves out of the mold 43 as shown. As a result, the molten metal 48 cooled by the mold 43 is extracted below the mold 43 in a solidified state.

One ends of the plurality of rod-shaped members 54 are fixed to the upper surface of the dummy bar 46, respectively. As each rod-shaped member 54, a long one is used. These rod-shaped members 54 are fixed to the dummy bar 46 in the same arrangement as the holes of the intermediate 41 to be produced. The rod-shaped member 54 is sequentially drawn into the molten metal 48 by moving downward of the dummy bar 46. Each rod-shaped member 54 is maintained in a vertical state by a holder (not shown).

Reference numerals 55a, 55b, and 55c are temperature sensors composed of, for example, K-type thermocouples, the temperature inside the continuous casting apparatus 40, the temperature of the molten metal 48 in the crucible 45, and the lowermost end of the rod-shaped member 1. Measure the temperature.

When the intermediate 41 is continuously cast using the continuous casting apparatus 40, the dummy bar 46 is first arranged in the mold 43, and then the holes of the intermediate 41 in which each rod-shaped member 54 should be produced on the upper surface of the dummy bar 46. Fixed in the same sequence as. Next, the molten metal 48 is poured into the crucible 45, and the dummy bar 46 starts moving downward.

By pouring the molten metal into the crucible 45, the molten metal 48 in the crucible 45 flows into the mold 43, and the space around the crucible 45 and each rod-shaped member 54 in the mold 43 is filled with the molten metal 48. The molten metal 48 that has flowed into the mold 43 due to the downward movement of the dummy bar 46 comes into contact with the cooled mold 43 and is rapidly cooled to sequentially solidify from the outer peripheral surface (mold 43 side), and the solidified portion. Moves down. On the other hand, when each rod-shaped member 54 moves downward due to the downward movement of the dummy bar 46, a new portion of the rod-shaped member 54 is drawn into the molten metal 48 by the moved length, and the space around them is filled with the molten metal 48. Is done. Then, by further moving the dummy bar 46 downward, the rod-shaped member 54 is further drawn into the molten metal 48, and the solidified portion of the molten metal 48 exits the mold 43. As a result, an intermediate 41 in which the structural material is solidified around the rod-shaped member 54 is obtained.

As the dummy bar 46 moves downward, the portion cooled by the mold 43 and solidified by the molten metal 48 is continuously sent out from the mold 43. As a result, the long intermediate 41 is continuously produced. The obtained intermediate 41 is subjected to a plasticization step and a removal step in the same manner as in the first example to obtain a porous structure.

The example of FIG. 8 is a batch type so-called semi-continuous casting method among the continuous casting methods, but an intermediate can be similarly produced by the full continuous casting method.

FIG. 9 shows an example of forming a plate-shaped intermediate by using a double roll casting method. In FIG. 9, the twin roll casting apparatus 60 includes a pair of casting rolls 61 and a pair of side weirs 62. The pair of casting rolls 61 are arranged horizontally side by side with a gap G having a predetermined width formed between them. Each casting roller 61 is rotationally driven at a constant speed by a drive mechanism (not shown), and their outer peripheral surfaces move from above toward the gap G. The pair of side weirs 62 are in surface contact with the upper portion of the end surface of each casting roll 61 in a state where they face each other so as to sandwich each casting roll 61 in the axial direction. As a result, the storage portion 63 is formed above the gap G by the outer peripheral surface of each casting roll 61 and each side weir 62. The storage unit 63 stores the molten metal 64 supplied from the pouring unit (not shown).

Further, the twin roll casting apparatus 60 is provided with a supply unit (not shown) for vertically feeding a plurality of rod-shaped members 65 into the gap G through the storage unit 63. The rod-shaped members 65 are supplied to the gap G in a state of being arranged in a line in the rotation axis direction of the casting roller 61 (the direction perpendicular to the paper surface in FIG. 9).

According to the above configuration, when the pair of casting rolls 61 are rotated, the solidified shells formed on the outer peripheral surfaces of the casting rolls 61 start contacting each other in the vicinity of the gap G and are melt-bonded from the gap G. It is sent down. At this time, each rod-shaped member 65 advances to the gap G through the storage portion 63, so that the space around the rod-shaped member 65 is filled with the molten metal 64. Then, the molten metal 64 around each rod-shaped member 65 solidifies to form a solidified shell. The solidified shell sent out from the gap G is further cooled by spraying cooling water from a cooling water nozzle (not shown), and the molten metal 64 is solidified with the rod-shaped member 65 arranged inside. As a result, a plate-shaped intermediate 67 is produced.

As shown in FIG. 10A, the structural portion 67a of the intermediate body 67 has a plate shape extending in the axial direction of the rod-shaped member 65. A plurality of holes 67b containing a rod-shaped member 65 are formed in the structure portion 67a, and the plurality of holes 67b are arranged in a row. The intermediate body 67 produced in this way becomes a plate-shaped porous structure 68 as shown in FIG. 10B by removing the rod-shaped member 65 from the holes 67b after being subjected to plastic working. The porous structure 68 has a plate shape in which a plurality of pores 68a are arranged in a row.

As a method for producing an intermediate of a porous structure, a conventionally known casting method such as the Hazelett method or the Properzi method can also be used.

In each of the above examples, when the intermediate of the porous structure was produced, a molten metal in which the structure material was in a liquid state was used, but the present invention is not limited to this, and the structure material is solidified instead of the molten metal. It may be produced by using a semi-solid slurry in a liquid coexisting state. FIG. 11 shows an example of producing an intermediate of a porous structure by a semi-solid casting method. In this example, an inclined cooling plate 72 for semi-solidifying the molten metal 71 is provided. The molten metal 71 is made into a liquid state by completely melting the structure material, and as the structure material, an alloy capable of coexisting with a solid-liquid state is used. The inclined cooling plate 72 is provided with, for example, a water channel (not shown) for cooling the inclined cooling plate 72 on the back surface side thereof.

The molten metal 71 flows on the inclined cooling plate 72 and is poured into the mold 73. As a result, the molten metal 71 is cooled while flowing down the inclined cooling plate 72, and becomes a semi-solid slurry 74 in a solid-liquid coexisting state in which primary crystals are present in the liquid, and the semi-solid slurry 74 is poured into the mold 73. It is hot water. After pouring the semi-solid slurry 74, for example, as in the first example, a plurality of rod-shaped members 77 held in the holder 76 in a predetermined arrangement are immersed in the semi-solid slurry 74 in the mold 73, and each rod-shaped member 77 is immersed. Is filled with the semi-solid slurry 74. The semi-solid slurry 74 in the mold 73 is cooled and solidified as it is to prepare an intermediate. In this way, the intermediate of the porous structure is made from the semi-solid slurry 74. The produced intermediate becomes a porous structure by removing the rod-shaped member from the holes after being subjected to plastic working.

When the semi-solid slurry 74 is used as the molten metal as described above, the temperature of the semi-solid slurry 74 can be made lower than the temperature of the molten metal in the liquid state. Therefore, the heat load on the rod-shaped member 77 can be reduced. This is effective in preventing the rod-shaped member 77 from being melted, and also has the effect of making it possible to select a material having a lower melting point (or solid phase temperature) as the rod-shaped member 77. You can expand the choice of materials.

In the above example, as the semi-solid slurry, a slurry that was made into a semi-solid state by lowering the temperature from the liquid state was used, but as a semi-solid slurry, it became a semi-melted state by raising the temperature of the structural material in the solid state. You may use the slurry. Further, an example of producing a semi-solid slurry using an inclined cooling plate has been described, but the present invention is not limited to this, and other methods for producing a semi-solid slurry such as mechanical stirring and electromagnetic stirring can also be used. .. Further, as long as it is in a solid-liquid coexisting state, it is not limited to the granulated semi-solid slurry, and it is also possible to simply hold it in the solid-liquid coexisting temperature range.

Regardless of whether the intermediate is produced by any of the above continuous castings or by using a semi-solid slurry, directional pores are surely formed from the produced intermediate as in the first example. A porous structure having high strength can be easily obtained.

In the above, an example of producing a porous structure having the same diameter of each rod-shaped member and having the same diameter of each pore has been described, but the present invention is not limited to this, and a plurality of types of rod-shaped members having different shapes are used. Porous structures having different pore diameters may be prepared. Further, as described above, by changing the cross-sectional shape of the rod-shaped members, the arrangement of the rod-shaped members, and the density of the rod-shaped members, a porous structure having the desired cross-sectional shape of pores, pore arrangement, and porosity can be produced. Can be done.

For example, FIG. 12 shows an example in which four types of pores 81a to 81d having different diameters are formed in the porous structure 81. The columnar porous structure 81 is formed with a pore 81a having the largest diameter at the center thereof. The remaining three types of pores 81b to 81d having different diameters are arranged in a circumferential shape for each diameter so that the diameter becomes smaller toward the outside, and are arranged concentrically around the pores 81a. The pores 81b to 81d are all arranged at equal intervals in the circumferential direction.

FIG. 13 shows an example in which three types of pores 82a to 82c having different diameters are formed in the prismatic porous structure 82. In the porous structure 82, two pores 82a having the largest diameters are provided in the central portion thereof in a direction parallel to one side surface of the porous structure 82. The pores 82b having an intermediate diameter are arranged in a rectangular shape so as to surround the pores 82a in a rectangular shape, and the pores 82c having the smallest diameter are arranged in a rectangular shape so as to surround the pores 82b in a rectangular shape.

FIG. 14 shows an example of a porous structure 83 having a honeycomb structure. A plurality of pores 83a of a regular hexagonal prism are formed in the porous structure 83, and honeycombs are arranged so that the peripheral surfaces of the adjacent pores 83a are parallel to each other. In the example of FIG. 14, the shape of the pores 83a is a regular hexagonal prism, but other shapes such as a cylindrical shape may be used.

In any of the examples of FIGS. 12 to 14, since the intermediate body with the rod-shaped member left is subjected to plastic working, the pores are surely formed without requiring a step of not crushing the holes. , A porous structure having high strength can be easily obtained. When using a plastic working method that does not change the cross-sectional shape of the intermediate before and after plastic deformation, such as plastic working by the ECAE method, a rod-shaped member having the same size and shape as the cross-sectional shape of the pore to be formed is formed. An intermediate may be prepared by arranging it in the same manner as the power pores, and a porous structure may be prepared from the intermediate. For example, when the porous structure 81 of FIG. 12 is manufactured, a rod-shaped member having the largest outer diameter is arranged at the center, and another rod-shaped member having the outer diameter smaller toward the outside with the rod-shaped member as the center. The members are arranged in a circle for each opening diameter. Further, when the porous structure 83 of FIG. 14 is manufactured, a rod-shaped member of a regular hexagonal prism may be used and arranged so that the peripheral surfaces of adjacent rod-shaped members are parallel to each other.

Further, in each of the above examples, an example of producing a porous structure having pores whose cross-sectional shape does not change has been described, but as described above, the cross-sectional shape of the pores of the porous structure may change. For example, as shown in FIG. 15 showing a vertical cross section of the porous structure 85, each pore 86 of the porous structure 85 has a tubular portion 86a having a constant inner diameter and a spherical portion 86b having a spherical shape having an inner diameter larger than that of the tubular portion 86a. And have. When producing such a porous structure 85, an intermediate is produced by using a rod-shaped member in which the portion corresponding to the tubular portion 86a has a cylindrical shape and the portion corresponding to the spherical portion 86b has a spherical shape. Can be done.

In each of the above examples, an example in which each of the plurality of pores formed in the porous structure has a directionality in the axial direction (longitudinal direction) has been described, but the directionality of the pores, that is, the extending direction is limited to this. It's not something. For example, a plurality of pores may be formed to be radial.

10,68 Porous structure 12,68a Pore 14,41,67 Manufacturing intermediate 16,54,65,77 Rod-shaped member 17,67b Pore 25,48,64 Molten 74 Semi-solid slurry

Claims (3)

In a method for manufacturing a porous structure having a plurality of directional pores,
The space around each of the plurality of arranged rod-shaped members was filled with a molten metal of an inorganic material, and the molten metal was solidified to form a plurality of holes in which each of the rod-shaped member and the rod-shaped member entered. An intermediate manufacturing process for obtaining a manufacturing intermediate having a structural portion of the inorganic material,
The plastic working process of plastic working the manufacturing intermediate and
It has a removal step of removing the rod-shaped member from the manufacturing intermediate that has undergone the plastic working step.
The rod-shaped member is made of either carbon, glass or alumina.
The inorganic material is a metal selected from aluminum, magnesium, titanium, nickel, gold, silver, copper, lead, molybdenum, zinc, iron, or an alloy containing the metal.
The plastic working step is a method for manufacturing a porous structure, characterized in that the manufacturing intermediate work is subjected to shear deformation by the ECAE method. The method for producing a porous structure according to claim 1, wherein the removing step is performed by removing the brittle-broken rod-shaped member or dissolving the rod-shaped member with an acid or an alkali. The method for producing a porous structure according to claim 1 or 2, wherein a semi-solid slurry in a solid-liquid coexisting state is used as the molten metal.

Images