JP2013198928A - Method of producing composite material formed by composite of matrix metal and solid-phase fine particles, and metal bonded grinding wheel produced by the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that the distribution of grinding particles of a metal bonded grinding wheel to be produced by a centrifugal-force mixing powder method is difficult to be controlled due to fluidity or the like.SOLUTION: Matrix metal powder and solid-phase fine-particle powder are mixed together to make mixed powder, and after the mixed powder is put into a casting mold, centrifugal force is applied to the casting mold and base-material melted metal produced by a melting furnace for casting is put into the casting mold, to produce a composite material wherein the matrix metal and solid-phase fine particles form a composite. During the production, the temperature of base-material molten metal produced by the melting furnace for casting is determined on the basis of apparent thermal conductivity of the mixed powder so that the matrix metal in the mixed powder is melted and the moving speed of the solid-phase fine particles by the centrifugal force becomes low. In addition, when the solid-phase particles are ununiformly dispersed even at the melting temperature determined on the basis of the thermal conductivity, ununiform dispersion can be improved by reducing the dimension of solid-phase particles.

Description

  The present invention relates to a method of manufacturing a composite material in which a matrix metal and solid phase fine particles are combined by utilizing centrifugal casting, and a metal bond grindstone manufactured by the method.

A metal bond grindstone is a grindstone in which abrasive grains such as diamond and SiC are compounded in a metal matrix. Such a metal bond grindstone is conventionally produced by a sintering method or an electrodeposition method. In the metal bond grindstone produced by the sintering method, the abrasive grains are uniformly dispersed throughout the grindstone. Therefore, the grindstone produced by the sintering method uses a large amount of abrasive grains. On the other hand, the grindstone produced by the electrodeposition method has an abrasive layer in which abrasive grains are dispersed only in the vicinity of the cutting edge, but has a drawback that peeling often occurs at the interface between the abrasive layer and the base metal. . Therefore, the metal bond grindstone produced by sintering or electrodeposition has a problem that the amount of diamond used is large and its durability is low.

  One of the methods for compositing fine solid phase particles in a metal matrix is a centrifugal mixed powder method disclosed in Patent Document 1, Non-Patent Document 1, and Non-Patent Document 2. In this technique, first, mixed powder 1 is prepared by mixing solid phase particles to be combined with a matrix metal powder (FIG. 1). Then, after the mixed powder 1 is put into the cylindrical mold 2, a centrifugal force is applied to the mixed powder 1 by rotating the cylindrical mold 2, and the mother melted in the melting furnace through the runner 3. The phase metal melt 4 is poured (FIG. 2). After solidification, fine solid phase particles are firmly fixed to the matrix metal, and a composite material can be obtained in which the fine solid phase particles are uniformly or gradiently dispersed in the matrix metal. The centrifugal force mixed powder method shown in FIGS. 1 and 2 is a method for producing a cylindrical composite material in which solid phase particles 5 are dispersed on the outer peripheral surface shown in FIG. 3, but a centrifugal casting apparatus as shown in FIG. 4 is used. Thus, a composite material in which the solid phase particles 5 are dispersed at the tip of the rod-shaped sample as shown in FIG.

  Up to now, a rod-shaped metal bond grindstone in which diamond particles are dispersed in a Cu matrix has been produced by a centrifugal mixing powder method using an apparatus as shown in FIG. 4 (Non-patent Document 3). As a result, it was possible to combine the diamond particles with the Cu matrix, but it was difficult to obtain the intended diamond particle distribution due to hot water flow or the like. Therefore, in order to manufacture a metal bond grindstone having a target abrasive grain distribution by the centrifugal mixed powder method, it is necessary to establish a dispersion control method of the abrasive grains.

JP 2008-284589 A

Yoshimi Watanabe, Nao Sato; Chemical Engineering, 54 (2009) 249-254. Yoshimi Watanabe, Yoshifumi Inaguma, Hisashi Sato and Eri Miura-Fujiwara; Materials, 2 (2009) 2510-2525. Yoshimi Watanabe, Eri Miura-Fujiwara, Hisashi Sato, Kunio Takekoshi, Hideaki Tsuge, Tadashi Kaga, Naoyuki Bando, Shigemasa Yamagami, Kazumasa Kurachi and Hisanori Yokoyama; International Journal of Materials and Puroduct Techonology, 42 (2011) 29-44.

  In view of the above points, an object of the present invention is to solve the problem that it is difficult to control the grain distribution of a metal bond grindstone produced by a centrifugal force mixed powder method due to the flow of molten metal.

  In order to achieve the above object, in the inventions described in claim 1 and claim 2, the centrifugal temperature is determined by setting the melting temperature of the matrix metal based on the apparent thermal conductivity of the mixed powder and the solid phase particle size in the mixed powder. We have invented a method for controlling the solid phase particle distribution of composite materials produced by the force-mixing powder method.

  In the manufacturing method according to the first and second aspects of the present invention, first, a mixed powder of a parent phase metal powder and a solid phase particle powder is prepared, and the mixed powder is cast in a centrifugal casting apparatus as shown in FIG. 6 Then, after melting the parent phase metal 7 in the melting furnace coil 8 at the melting temperature determined by the method described below, a centrifugal force is applied to the casting mold 6 having the mixed powder, Pour into the casting mold 6. Thus, a composite material in which the solid phase particles 5 are uniformly dispersed at the tip of the rod-shaped cast material as shown in FIG. 5 is manufactured. The melting temperature of the parent phase metal is determined by the following procedure. The apparent thermal conductivity of the prepared mixed powder is estimated by the following Maxwell equation.

Where l _eff , l _m , l _d and V _d are the apparent thermal conductivity of the mixed powder, the thermal conductivity of the base material, the thermal conductivity of the solid phase particles and the volume fraction of the solid phase particles, respectively. . Based on the apparent thermal conductivity of the calculated mixed powder, a melting temperature at which the matrix metal in the mixed powder can be dissolved is determined. However, in order to determine this melting temperature, the relationship between the apparent thermal conductivity of the mixed powder, the temperature of the parent metal melt (melting temperature) and the quality of the cast material obtained thereby is grasped in advance, and the relationship is determined. You need to create a database to show. That is, an appropriate melting temperature must be determined from the database for the apparent thermal conductivity of the mixed powder used in casting. In addition, if solid phase particles are dispersed non-uniformly even by centrifugal casting at a melting temperature determined based on the thermal conductivity, it can be improved by reducing the size of the solid phase particles. That is, a technical method of the present invention is a manufacturing method for manufacturing a composite material in which solid phase particles are uniformly dispersed according to the melting temperature of the parent phase metal and the size of the solid phase particles in consideration of the apparent thermal conductivity of the mixed powder. .

  In the manufacturing method according to the third and fourth aspects of the present invention, first, a mixed powder of a Cu matrix powder and an abrasive powder is prepared, and the mixed powder is put into a mold of a centrifugal casting apparatus as shown in FIG. . Thereafter, the apparent thermal conductivity of the mixed powder is calculated from Equation 1, and after preparing a Cu mother phase melt at the melting temperature determined based on it, a centrifugal force is applied to the casting mold having the mixed powder, A Cu matrix melt is poured into the casting mold. Thereby, the metal bond grindstone in which the abrasive grains are uniformly dispersed at the tip portion of the rod-shaped cast material is manufactured. Further, even if the abrasive grains are dispersed non-uniformly by the centrifugal mixed powder method at the melting temperature determined based on the thermal conductivity, it is also possible to improve by reducing the size of the abrasive grains. That is, the manufacturing method of manufacturing a metal bond grindstone in which abrasive grains are uniformly dispersed according to the molten metal temperature and the abrasive grain size of the Cu mother phase molten metal in consideration of the apparent thermal conductivity in the mixed powder of Cu and abrasive grains. As a means.

Further, the centrifugal casting apparatus shown in FIG. 4 described in claims 1 to 4 is not limited to the above-described embodiment, and can be appropriately modified and applied without departing from the gist thereof. For example, a centrifugal casting apparatus of a type using a cylindrical mold as shown in FIG. 1 and a centrifugal casting apparatus having a casting mold having a complicated shape such as a triangular prism, a quadrangular prism, and a polygonal prism can be applied. Further, the base metal powder and the base metal molten metal described in claim 2 do not have to be the same type of metal or alloy. For example, the base metal powder is an iron alloy or a base metal molten metal. Combinations of all other metals and alloys, such as iron alloys, are also applicable.

It is the figure which drawn typically the method of throwing into the rotating cylindrical-shaped metal mold | die 2 the mixed powder 1 of the mother phase metal powder and solid-phase particle powder in the centrifugal force mixed powder method which is background art of this invention. It is the figure which drawn typically the method of pouring the mother phase metal melt 4 in the rotating cylindrical mold 2 in the centrifugal force mixed powder method which is the background art of the present invention. It is the figure which drawn typically the cylindrical composite material which has a solid-phase particle on the outer peripheral surface produced using the centrifugal force mixed powder method which is the background art of this invention. It is the figure which drawn typically the centrifugal casting apparatus used when producing a rod-shaped composite material with the centrifugal force mixed powder method which is the background art of this invention. It is the figure which drawn typically the rod-shaped composite material produced by the centrifugal force mixed powder method which is the background art of this invention using the centrifugal casting apparatus shown in FIG. It is a schematic diagram of the casting mold used in the centrifugal mixed powder method in the embodiment of the present invention. It is a stereoscopic microscope picture which shows the external appearance of the Cu-diamond composite material manufactured by the centrifugal force mixed powder method in the embodiment of the present invention. The melting temperature of the Cu matrix metal is 1200 ° C. At the tip of the composite material, there is a mixed powder region 10 in which diamond particles are dispersed. It is a stereoscopic microscope picture which shows the external appearance of the Cu-diamond composite material manufactured by the centrifugal force mixed powder method in the embodiment of the present invention. The melting temperature of the Cu matrix metal is 1250 ° C. At the tip of the composite material, there is a mixed powder region 10 in which diamond particles are dispersed. It is a stereoscopic microscope picture which shows the external appearance of the Cu-diamond composite material manufactured by the centrifugal force mixed powder method in the embodiment of the present invention. The melting temperature of the Cu matrix metal is 1300 ° C. At the tip of the composite material, there is a mixed powder region 10 in which diamond particles are dispersed. It is the scanning electron micrograph which showed the fine structure in the mixed powder area | region 10 of the Cu-diamond composite material manufactured by the centrifugal force mixed powder method in embodiment of this invention. The melting temperature of the Cu matrix metal is 1200 ° C. It is the scanning electron micrograph which showed the fine structure in the mixed powder area | region 10 of the Cu-diamond composite material manufactured by the centrifugal force mixed powder method in embodiment of this invention. The melting temperature of the Cu matrix metal is 1250 ° C. It is the scanning electron micrograph which showed the fine structure in the mixed powder area | region 10 of the Cu-diamond composite material manufactured by the centrifugal force mixed powder method in embodiment of this invention. The melting temperature of the Cu matrix metal is 1300 ° C. It is a stereoscopic microscope picture which shows the external appearance of the Cu-SiC composite material manufactured by the centrifugal force mixed powder method in embodiment of this invention. This Cu—SiC composite material was produced by melting a Cu matrix metal at 1300 ° C. It is the scanning electron micrograph which showed the fine structure in the mixed powder area | region 10 of the Cu-SiC composite material manufactured by the centrifugal force mixed powder method in embodiment of this invention. The melting temperature of the Cu matrix metal is 1300 ° C. In the centrifugal mixed powder method according to the embodiment of the present invention, a tip portion of a Cu-diamond composite material manufactured by dissolving diamond matrix metal at 1300 ° C. using diamond abrasive grains having a particle size of 150-170 μm It is a graph which shows the diamond abrasive grain volume fraction change in. In the centrifugal mixed powder method according to the embodiment of the present invention, a tip portion of a Cu-diamond composite material manufactured by melting diamond matrix metal at 1300 ° C. using diamond abrasive grains having a particle diameter of 60-70 μm It is a graph which shows the diamond abrasive grain volume fraction change in. It is a schematic diagram of the metal bond grindstone for gyro type | mold drilling machines produced using the Cu-diamond composite material manufactured with the centrifugal force mixed powder method in embodiment of this invention. The stereomicrograph which shows the result of the drilling test of carbon fiber reinforced resin (CFRP) by the metal bond grindstone for gyro-type drilling machines manufactured by embodiment of this invention.

(First embodiment)
Cu-25 vol. Made of Cu powder having a particle diameter of 15 μm or less as a base metal powder and diamond particles having a particle diameter of 150-170 μm as abrasive grains. Only 16.2 g of a% diamond mixed powder was produced, and the mixed powder was filled in a casting mold shown in FIG. When the thermal conductivity of Cu and diamond is 402 W / mK and 2000 W / mK, respectively, the apparent thermal conductivity of the mixed powder is 602 W / mK. Then, 130 g of pure Cu ingot made of a parent phase metal is charged in a melting furnace for casting and heated to a melting temperature of 1200 ° C., 1250 ° C., and 1300 ° C. to obtain a Cu parent phase molten metal. The Cu mother phase molten metal was poured into a casting mold. As a result, a composite material in which diamond abrasive grains were dispersed at the tip of the cast material as shown in FIG. 7 was produced. Stereomicrographs shown in FIGS. 7 (a), (b) and (c) are macrostructures of Cu-diamond composite materials produced at melting temperatures of 1200 ° C., 1250 ° C. and 1300 ° C., respectively. At the composite material tips prepared at melting temperatures of 1200 ° C. and 1250 ° C., the Cu powder in the mixed powder was not dissolved, and a part of the Cu powder dropped out in the mixed powder region 10. On the other hand, in the Cu-diamond composite material produced at 1300 ° C., Cu powder produced by the composite material produced at 1200 ° C. and 1250 ° C. did not fall off. Scanning electron micrographs shown in FIGS. 8 (a), (b) and (c) show the tips of the Cu-diamond composite material (mixed powder region 10) prepared at melting temperatures of 1200 ° C., 1250 ° C. and 1300 ° C., respectively. The microstructure is shown in FIG. Also from this photograph, it can be seen that the Cu powder in the mixed powder is dissolved only in the composite material produced at the melting temperature of 1300 ° C. That is, when using a mixed powder having an apparent thermal conductivity of 626 W / mK, a melting temperature of 1300 ° C. or higher is required.

  Therefore, in order to verify this, an attempt was made by producing a mixed powder using SiC, which has a lower thermal conductivity than diamond, as abrasive grains. Cu-25 vol. Made of Cu powder having a particle diameter of 15 μm or less as a base metal powder and SiC particles having a particle diameter of 150 to 170 μm as abrasive grains. % SiC mixed powder was prepared, and the mixed powder was filled in a casting mold. When the thermal conductivity of Cu and SiC is 402 W / mK and 600 W / mK, respectively, the apparent thermal conductivity of the mixed powder is 446 W / mK. Then, 130 g of pure Cu ingot is loaded into the melting furnace with the parent phase metal and heated to a melting temperature of 1300 ° C. to form a Cu molten metal, and then a centrifugal force of gravity multiple 35G (gravity multiple 1G corresponds to the gravitational field) is applied. The Cu matrix melt was poured into a casting mold. As a result, a composite material in which SiC particles were dispersed at the tip of the composite material as shown in FIG. 9 was manufactured. As can be seen from FIG. 9, in the cast material using SiC particles, the dissolution of the Cu powder in the mixed powder region 10 was not completed, and a part of the Cu powder dropped off. Therefore, when the apparent thermal conductivity of the mixed powder is small, it is necessary to dissolve the Cu matrix metal at a higher temperature. That is, it is possible to control the solid phase particle dispersion of the composite material by the centrifugal mixed powder method based on the apparent thermal conductivity of the mixed powder.

  FIG. 10 is a graph showing the change in the volume fraction of the abrasive grains with the distance from the tip of the composite material in the Cu-diamond composite material produced by the above centrifugal force mixed powder method at a molten metal temperature of 1300 ° C. of the Cu matrix. . From this graph, the diamond abrasive grain distribution in the Cu-diamond composite material was significantly different from the target value. This is because the diamond abrasive grains have moved in the direction opposite to the centrifugal force direction due to the centrifugal force. As shown in Non-Patent Document 1, the moving speed of the solid phase particles in the liquid phase becomes slower as the solid phase particle diameter becomes smaller. Therefore, it is possible to control the solid phase particle distribution in the cast material by reducing the diameter of the diamond abrasive grains. Therefore, a Cu-diamond composite material was produced under the same casting conditions using diamond particles having a particle diameter of 60-70 μm as abrasive grains. FIG. 11 is a graph showing the distribution of diamond abrasive grains in the cast material. From this graph, it can be seen that the control of the distribution of diamond abrasive grains is successful.

  A grindstone 11 is cut out from a Cu-diamond composite material produced by a centrifugal force mixed powder method, and a gear 12 is attached to produce a metal bond grindstone for a gyro-type drilling machine as shown in FIG. CFRP) drilling test was conducted. A stereomicrograph showing the result is shown in FIG. From this result, drilling of CFRP without burrs has been successful, and the metal bond grindstone produced by this technology is effective as a grindstone for difficult-to-work materials.

  1 A mixed powder produced by mixing a matrix metal powder and a solid phase particle powder.

  2 Cylindrical mold having a cavity and rotatable.

  3 A runner for pouring mixed powder or molten metal of the parent phase metal into a cylindrical mold.

  4 A matrix metal melt that is poured into a cylindrical mold to form a matrix metal of a composite material.

  5 Solid phase particles in a cylindrical composite material produced by the centrifugal force mixed powder method. The solid phase particles are dispersed only on the outer peripheral surface of the composite material.

  6 A casting mold in a centrifugal casting apparatus for producing a rod-shaped composite material.

  7 It is a parent phase metal before dissolution.

  8 A high-frequency coil for melting the parent phase metal.

9 A core inside the casting mold.
10 This is a mixed powder region in which a mixed powder at the tip of a rod-like Cu-diamond composite material or a Cu-SiC composite material manufactured by the centrifugal force mixed powder method was present.
11 A portion of a grindstone in which diamond abrasive grains in a metal bond grindstone are dispersed.
12 A gear required for rotating a metal bond grindstone with a gyro drilling machine.

Claims (4)

  The mixed metal powder and the solid phase fine particle powder were mixed to prepare a mixed powder. After the mixed powder was put into a casting mold, a centrifugal force was applied to the casting mold and the mixed powder was prepared in a casting melting furnace. A method of producing a composite material in which a matrix metal and solid phase fine particles are combined by pouring a matrix molten metal into a casting mold, wherein the temperature of the matrix phase melt produced in the melting furnace for casting is The matrix phase is determined based on the apparent thermal conductivity of the mixed powder so that the matrix metal in the mixed powder is melted and the moving speed of the solid phase fine particles is reduced by centrifugal force. A method for producing a composite material in which metal and solid phase fine particles are combined. In the manufacturing method, the solid phase is controlled by reducing the size of the solid phase particles when the solid phase particles are unevenly dispersed even in the centrifugal casting at the melting temperature determined based on the thermal conductivity. A method for producing a composite material in which metal and solid phase fine particles are combined. The matrix metal powder is Cu powder, brass, bronze, or steel;
The method for producing a composite material in which the matrix metal and the solid phase fine particles are combined according to claim 1 or 2, wherein the solid phase fine particle powder is diamond, SiC, alumina, or CBN. A metal bond grindstone manufactured by a method for manufacturing a composite material in which the matrix metal and solid phase fine particles are combined.