JP2010194582A - Method for producing hollow casting, and method for producing hollow forming member used therein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a hollow casting provided with a cavity in accordance with a design value, in a simple working process. <P>SOLUTION: In the method for producing the hollow casting having the cavity formed inside, a hollow forming member 10 where a hollow part 12 having a shape same as that of the cavity is included in a state where a part is opened, and the opened part is integrally fitted with a pore member 15 provided with many pores 15a through which air passes but the molten metal 21 of the casting base material metal 20 does not pass, is arranged in a mold 50. The molten metal 21 of the casting base material metal 20 is poured into the mold 50, and is insert-cast with the casting base material metal 20 poured with the hollow forming member 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a hollow casting having a cavity inside for the purpose of heat insulation, such as a heat insulating piston for an internal combustion engine.

  In order to manufacture a hollow casting having a cavity inside for the purpose of heat insulation, such as a heat insulating piston for an internal combustion engine, a hollow forming member having a hollow portion having the same shape as the cavity to be formed is placed in the mold in advance. In addition, a manufacturing method is conceivable in which a molten cast metal material is poured into the mold, and the formed hollow forming member is cast by the cast preform metal.

  An example of the hollow forming member is a Fe-Mn sintered body made of a material having a melting point higher than the molten metal temperature of a casting base metal, and having the hollow part opened in a part thereof, for example. A hollow forming member composed of a main body part and a closing member made of, for example, a stainless steel plate, which is integrally fixed to the main body part so as to seal the open part of the hollow part, can be considered. However, when the hollow forming member of this form is cast, the air in the hollow portion, which is a sealed space, is rapidly expanded by the heat of the molten metal, and the hollow portion may be deformed to cause blistering.

  As a hollow forming member that eliminates the inconvenience, a solid substance that is solid at room temperature and gasifies or melts at a temperature lower than the melting point of the casting base metal is previously formed in the shape of the cavity, and the solid substance is cast. Patent Document 1 or Patent Document 2 describes a hollow forming member that is covered with a porous material that is stable against a base metal melt. When forming a hollow casting, the hollow forming member is placed in a mold, and a cast metal in which the hollow forming member is cast by pressure casting by pouring a molten metal of a casting base metal. An opening communicating with the solid substance is formed in the casting, and then the solid substance is gasified or melted by being heated to a temperature lower than the casting base metal and equal to or higher than the melting point of the solid substance to flow out of the opening. To remove. After the removal, the opening is closed with a screw or the like to obtain a hollow casting having a cavity inside.

JP-B-2-36350 Japanese Patent Publication No. 3-9821

  According to the method for producing a hollow casting described in Patent Documents 1 and 2, a hollow casting having a cavity having a shape as designed can be obtained without causing deformation or shaking due to heat during casting. However, an operation for providing an opening for removing a gasified or melted substance with respect to a cast product after casting, and a work for removing a low-melting-point substance embedded in a hollow part by gasification or melting, The operation | work which closes the said opening after removal is required, and an operation | work is a little complicated.

  The present invention has been made in view of the above circumstances, and discloses a new method for producing a hollow casting that can produce a hollow casting having a cavity as designed by a simpler work process. This is the first problem. Furthermore, it is set as the 2nd subject to disclose the manufacturing method of the hollow formation member used there.

  A method for manufacturing a hollow casting having a cavity inside according to the present invention comprises a hollow part having the same shape as the cavity in a state where a part thereof is open, and at least air passes through the open part, but of the casting base metal. A hollow forming member in which a pore member having a large number of pores through which molten metal does not pass is integrally attached is placed in a mold, and a molten metal of a casting base metal is poured into the mold to inject the hollow forming member. It is characterized by being cast with a cast metal base metal that has been heated.

  According to the manufacturing method of the present invention, by pouring the molten metal into the mold in which the hollow forming member is disposed, the hollow forming member is heated and the air in the hollow portion expands. Since it can escape through the pores, no swelling occurs in the hollow portion. Further, the molten metal does not enter the hollow portion due to the pore member. Therefore, the shape of the hollow part formed in the hollow forming member is maintained as it is, and a cavity as designed is formed in the hollow casting after manufacture. Also, the main manufacturing processes are only a process of placing the hollow forming member in the mold and a process of pouring a molten metal of the casting base metal into the mold, and the manufacturing process is greatly simplified.

  The present invention can be applied to any hollow casting manufacturing method. As an example, it is possible to manufacture a heat insulating piston of an internal combustion engine using the cavity as a heat insulating portion.

  The present invention also provides a method for producing the hollow forming member used in the method for producing a hollow casting described above, wherein the pore member is placed in a mold, and disappears by heating in the same shape as the hollow portion at an appropriate position thereon. A method for producing a hollow forming member is also disclosed, in which a lost material is placed, a metal material is placed in a mold, and then molded and heated to disappear the lost material to form a hollow portion.

  With the above manufacturing method, a hollow forming member having a hollow portion having an arbitrary shape can be easily manufactured. The material of the disappeared material is not particularly limited as long as it is a material that is gasified by heat when the metal material is molded and disappears, and examples thereof include paper and plastic.

  The main body constituting the hollow forming member is a material having a melting point higher than the molten metal temperature of the casting base metal when the hollow forming member is manufactured using the hollow forming member and is stable to the molten casting base metal. Can be made of any metal material. As an example, for example, when the casting base metal is an aluminum-based metal, an iron-based metal powder is used. Examples of the forming process include a sintering process. In addition, metal materials such as ferromanganese alloy powder and titanium alloy powder can be used.

  The pore member constituting the hollow forming member should also be a material having a melting point higher than the molten metal temperature of the casting base metal when the hollow forming member is manufactured using the hollow forming member and stable to the molten casting base metal. As an example, a metal material such as stainless steel or low alloy steel, or a ceramic material can be given as an example. The size may be appropriately set in consideration of the size of the pores formed in the pore member, the viscosity of the cast base metal molten metal, etc., but when the cast base metal is an aluminum-based metal, it is about 60 to 200 mesh.

  According to the present invention, it is possible to manufacture a hollow casting having a cavity as designed by a simple work process.

The figure explaining the one aspect | mode of the hollow formation member used with the manufacturing method of the hollow casting by this invention. The figure explaining the one aspect | mode for manufacturing a hollow formation member. The figure explaining the other aspect which manufactures a hollow formation member. The figure explaining the further another aspect which manufactures a hollow formation member. The figure explaining the one aspect | mode which implements the manufacturing method of the hollow casting by this invention using the hollow formation member shown in FIG. The figure explaining the test piece used in experiment. The figure explaining the method of experiment. The figure which shows the heat insulation piston manufactured by the manufacturing method of the hollow casting by this invention.

  Hereinafter, the present invention will be described based on embodiments with reference to the drawings. FIG. 1 is a view for explaining an embodiment of a hollow forming member used in the method for producing a hollow casting according to the present invention, FIG. 2 is a view for explaining an embodiment for producing the hollow forming member, and FIG. 3 is for producing the hollow forming member. FIG. 4 is a diagram for explaining another embodiment for producing a hollow forming member, and FIG. 5 is a diagram illustrating a method for producing a hollow casting according to the present invention using the hollow forming member shown in FIG. It is a figure explaining one mode to do. Moreover, FIG. 6 is a figure which shows an example of the heat insulation piston manufactured with the manufacturing method of the hollow casting by this invention.

  As shown in the perspective view of FIG. 1A viewed from the bottom side and the cross-sectional view of FIG. 1B, the hollow forming member 10 is formed of a main body 11 and a pore member 15. In this example, the main body portion 11 has a columnar shape, and a cylindrical hollow portion 12 is formed therein so as to open the bottom surface side. The hollow portion 12 may have any overall shape on the condition that a part of the hollow portion 12 is open and the other is airtightly surrounded by the main body portion 11.

  The pore member 15 has a large number of pores 15a and is integrally fixed to the side of the main body portion 11 where the open surface of the hollow portion 12 is located by appropriate means. In the illustrated example, the pore member 15 is approximately the same size as the bottom surface of the main body portion 11, but may be any size that can cover at least the open portion of the hollow portion 12.

  Further, the size of the pores 15a formed in the pore member 15 is such that the molten metal 21 of the casting base metal 20 used when the hollow casting 30 is cast using the hollow forming member 10, as shown in FIG. Is set to a size that cannot pass through. As described above, when the molten metal 21 is an aluminum-based metal, the size of the pores 15a may be in the range of 60 to 200 mesh.

  The main body 11 and the pore member 15 constituting the hollow forming member 10 have a melting temperature higher than the temperature of the molten metal 21 of the casting base metal 20 used when the hollow casting 30 is cast using the hollow forming member 10. It can be made of an appropriate material that is high and stable to the casting base metal 20. For example, the main body 11 is made of an iron-based metal, and the pore member 15 is made of a stainless mesh plate.

  FIG. 2 shows one method of manufacturing the hollow forming member 10. In this method, the aforementioned pore member 15 is prepared first, and a vanishing material 16 made of paper, for example, is placed thereon as shown in FIG. The vanishing material 16 has the same three-dimensional shape as the cavity formed in the hollow casting 30 to be obtained. As shown in FIG. 2 (b), after setting it in an appropriate mold 17, as shown in FIG. 2 (c), it is filled with the powder of the appropriate metal material 18 described above. And press-molding. The molded member is taken out from the mold 17 and sintered. The lost material 16 is combusted by the heat during the sintering process, and the combustion gas is exhausted through the pores 15 a of the pore member 15. As a result, as shown in FIG. 2D, the hollow forming member 10 including the main body portion 11 and the pore member 15 and having the hollow portion 12 therein is obtained. The metal material 18 need not be a metal powder as long as it can be formed into a shape required for heating, and it is not essential to perform a sintering process.

  FIG. 3 shows another method of manufacturing the hollow forming member 10. Here, two vanishing materials 16 a and 16 b having different shapes are placed on the pore member 15 as the vanishing material 16. Using this, a hollow forming member having two hollow portions of different shapes can be manufactured by taking the method shown in FIG. Of course, a plurality of vanishing materials 16 having the same shape can be used, or three vanishing materials 16 having different shapes can be used. As a result, by adopting this manufacturing method, it is possible to easily manufacture the hollow forming member 10 including the hollow portions 12 having any number and any shape.

  FIG. 4 shows another method of manufacturing the hollow forming member 10. Here, as shown in FIG. 4A, the body portion 11 having the hollow portion 12 opened on one side is formed by an appropriate forming method or cutting method known in the art. The hollow forming member 10 is completed as shown in FIG. 4B by fixing the fine pore member 15 to the bottom surface of the main body 11 integrally by an appropriate method.

  FIG. 5 shows an aspect in which the hollow casting 30 is formed using the hollow forming member 10 described above. In this example, the hollow forming member 10 is set in the mold 50 so that the pore member 15 is on the upper surface side, and the molten metal 21 of the casting base metal 20 is poured into the mold 50 from above. . As described above, the pore member 15 includes a large number of pores 15a through which air passes but the molten metal 21 of the casting base metal 20 does not pass, and the air in the hollow portion 12 expanded by the heat of the molten metal is fine. Since the air is exhausted from the hole 15a to the outside of the hollow portion 12, the shape of the hollow portion 12 does not change. Further, the molten metal 21 does not enter the hollow portion 12.

  By pouring the molten metal 21 of the casting base metal 20, the hollow forming member 10 is cast by the casting base metal 20 to be a hollow casting 30. Then, a hollow having the same shape as the hollow portion 12 formed in the hollow forming member 10 is formed in the hollow casting 30 after manufacture. Even if the sintered body is cast into an aluminum-based metal as it is, the joint surface may not be alloyed. In order to solve this problem, it is desirable to set the hollow forming member 10 in the mold 50 after performing an aluminizing treatment in molten aluminum for about 1 to 2 minutes.

  In addition, the present inventors performed a test for examining whether or not the molten metal passes through the pore member 15. FIG. 6 shows a test piece TP used for the test, and FIG. 7 shows a test method. In the test piece TP, two types of 60-mesh and 200-mesh thin plates of SUS304 were used as the pore member 15 and held by iron rings 19a and 19b. As shown in FIG. 7, two test pieces TP were set in the mold 50, molten aluminum (AC8A) 21 having a temperature of 720 ° C. was poured, and the test piece TP was cast. After cooling, the casting was taken out and the back surface was observed. As a result, in any of the test beads TP, the iron ring 19b located in the lower part was hollow and the pore member 15 could be visually observed from below. . Thereby, it has confirmed that the pore member 15 which does not let a molten metal pass exists.

  FIG. 8 shows a heat insulating piston 60 of an internal combustion engine using the above-described manufacturing method and using a cavity formed by the hollow portion 12 of the hollow forming member 10 as a heat insulating portion. The heat insulating piston 60 is formed by pouring the casting base metal 20 into the molding die in a state where the hollow forming member 10 is disposed in a molding die (not shown), and a hollow portion (cavity) of the hollow forming member 10 is formed. 12 functions as a heat insulating part.

10: Hollow forming member,
11 ... Main body of the hollow forming member,
12 ... hollow part,
15 ... The pore member of the hollow forming member,
15a: pores of the pore member,
16, 16a, 16b ... vanishing material,
17 ... mold,
18 ... Metal material 20 ... Cast base metal,
21 ... molten metal,
30 ... hollow casting,
50 ... mold,
60 ... A heat-insulating piston of an internal combustion engine by the method for producing a hollow casting according to the present invention.

Claims (3)

  A method for producing a hollow casting having a cavity therein, comprising a hollow part having the same shape as the cavity in a partially opened state, wherein at least the open part passes air but is a molten metal of a casting base metal A hollow forming member having a large number of fine pore members that are integrally attached is disposed in the mold, and a molten metal of a casting base metal is poured into the mold to pour the hollow forming member. A method for producing a hollow casting, characterized by casting with a cast base metal.   The method for manufacturing a hollow casting according to claim 1, wherein a heat insulating piston of an internal combustion engine having the cavity as a heat insulating portion is manufactured.   A method for producing the hollow forming member used in the method for producing a hollow casting according to claim 1, wherein the pore member is placed in a mold, and heating is performed in the same shape as the hollow portion at an appropriate position above the member. A method for producing a hollow forming member, characterized in that a disappeared material that disappears is placed, a metal material is placed in a mold and molded, heated, and disappeared to form a hollow part.

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