Grinding wheel and method for manufacturing the same

Abstract

A grinding wheel includes a plurality of super abrasive grains arranged so as not to contact one another; a vitrified bond formed like a bridge that bridges the plurality of super abrasive grains one another, and bonding the plurality of super abrasive grains one another; a plurality of fine grains arranged in the vitrified bond while forming a group and interposed between the plurality of super abrasive grains so that the plurality of super abrasive grains are arranged so as not to contact one another; and pores formed around the vitrified bond.

What is claimed is: 
     
         1 . A grinding wheel comprising:
 a plurality of abrasive grains arranged so as not to contact one another;   a bond formed like a bridge that bridges the plurality of abrasive grains one another, and bonding the plurality of abrasive grains to one another;   a plurality of fine grains that are arranged in the bond while forming a group and that are interposed between the plurality of abrasive grains so that the plurality of abrasive grains are arranged so as not to contact one another; and   pores formed around the bond.   
     
     
         2 . The grinding wheel according to  claim 1 , wherein an average grain size of the plurality of fine grains is equal to or smaller than one-fifth of an average grain size of the group of the plurality of fine grains. 
     
     
         3 . The grinding wheel according to  claim 1 , wherein
 an average separation distance between adjacent two abrasive grains, of the plurality of abrasive grains, bonded to each other by the bond is equal to or smaller than an average grain size of the abrasive grains.   
     
     
         4 . The grinding wheel according to  claim 1 , wherein
 the plurality of fine grains are bonded to one another by the bond.   
     
     
         5 . The grinding wheel according to  claim 1 , wherein
 the plurality of fine grains are made of ceramic.   
     
     
         6 . A method for manufacturing the grinding wheel according to  claim 1 , comprising:
 (a) binding, for granulation, the plurality of fine grains to one another with a binding member to form a plurality of granulated powders;   (b) mixing the plurality of granulated powders, the plurality of abrasive grains in a state before formation of the grinding wheel, and the bond in a powdery state and arranging each of the plurality of granulated powders between adjacent abrasive grains to form an intermediate molding;   (c) feeding the intermediate molding into a molding die and pressurizing the interior of the molding die to form a pressed molding; and   (d) heating the pressed molding such that part or all of the binding member forming the granulated powders disappears to form binding member space between the plurality of fine grains, the bond that is melted flows into the binding member space and space between the plurality of fine grains other than the binding member space, and adjacent abrasive grains are bridged with the bond containing the plurality of fine grains forming a group, the group formed by disappearance of part or all of the binding member from the granulated powders.   
     
     
         7 . The method for manufacturing the grinding wheel, according to  claim 6 , wherein
 the binding member used in the step (a) is a binder that disappears at a temperature lower than a softening point of the bond.   
     
     
         8 . The method for manufacturing the grinding wheel, according to  claim 6 , wherein
 the binding member used in the step (a) is a mixture of a binder that disappears at a temperature lower than a softening point of the bond, and the bond.   
     
     
         9 . The method for manufacturing the grinding wheel, according to  claim 6 , further comprising:
 (e) classifying the plurality of granulated powders formed in the step (a) to extract granulated powders having a uniform diameter for supplying the granulated powders to the step (b), wherein   the plurality of granulated powders formed in the step (a) are each formed in a generally spherical shape.