Method for producing high-porosity vitrified grinding stone

Abstract

A method for producing a high-porosity vitrified grinding stone that has a plurality of pores communicating with each other. The method includes: (a) a grinding-stone-material preparing step of obtaining a grinding-stone raw material slurry that is a mixture fluid of abrasive grains, a vitrified bond, a gellable water-soluble polymer and a water; (b) a molding step of obtaining a molded body, by gelling the grinding-stone raw material slurry with use of a molding mold; (c) a freeze vacuum drying step of generating a plurality of frozen particles inside the molded body by freezing the molded body, and placing the molded body under a vacuum state, so as to sublimate the frozen particles generated inside the molded body for thereby drying the molded body; and (d) a firing step of obtaining the high-porosity vitrified grinding stone, by binding the abrasive grains with the vitrified bond by firing the molded body.

1 . A method for producing a high-porosity vitrified grinding stone that has a plurality of pores communicating with each other,
 the method comprising:   a grinding-stone-material preparing step of obtaining a grinding-stone raw material slurry that is a mixture fluid of abrasive grains, a vitrified bond and a water, such that a gellable water-soluble polymer is dissolved in the mixture fluid;   a molding step of obtaining a molded body, by gelling the grinding-stone raw material slurry with use of a molding mold;   a freeze vacuum drying step of generating a plurality of frozen particles inside the molded body by freezing the molded body after the molding step, and placing the molded body under a vacuum state, so as to sublimate the frozen particles generated inside the molded body for thereby drying the molded body; and   a firing step of obtaining the high-porosity vitrified grinding stone, by binding the abrasive grains with the vitrified bond by firing the molded body after the freeze vacuum drying step.   
     
     
         2 . The method of the according to  claim 1 ,
 wherein the pores are formed in places in which the frozen particles had been present in the grinding-stone raw material slurry, after the frozen particles have been sublimated at the freeze vacuum drying step.   
     
     
         3 . The method according to  claim 1 ,
 wherein, at the freeze vacuum drying step, the frozen particles are generated in the grinding-stone raw material slurry which is gelled and which constitutes the molded body, whereby the abrasive grains and the vitrified bond are gathered to base portions surrounding the frozen particles, and   wherein, at the firing step, the base portions are fired whereby bond bridges, which are shells that surround the pores, are formed from the base portion.   
     
     
         4 . The method according to  claim 1 ,
 wherein a pore volume ratio of the high-porosity vitrified grinding stone is 65-90 volume%.   
     
     
         5 . The method according to  claim 1 ,
 wherein a specific gravity of the high-porosity vitrified grinding stone is 0.34-1.48.   
     
     
         6 . The method according to  claim 3 ,
 wherein the abrasive grains have a median grain diameter that is smaller than a thickness of the bond bridges constituting the shells of the pores.