| 摘要 |
PURPOSE:To suppress the thermal expansion coefficient of a grindstone having a grinding-grain layer on the outer peripheral part of a core metal, to a small value, by forming the core metal with the resin binder containing, in a peculiaric % specific volume, the filler having a linear expansion coefficient of a specific value or less. CONSTITUTION:A core metal is formed with the resin binder which contains the filler in 25-80% by specific volume, said filler having a linear expansion coefificient. The ordinary bakelite, shellac resin, etc. are used as the basic material for the resin binder, and alpha-spodumene, hollow glass, etc. are used as fillers. The content of the fillers in the binder 25-80% by specific volume of the total amount of the binder, and when the content is less than 25%, the linear expansion coefficient can not be suppressed to a sufficiently small value, and when the content exceeds 80%, the mechanical strength of the core metal is sometimes insufficient. Further, it is desirable to exceedingly inrease the content of the filler in the binder, in order to hold the strength of the core metal and the holding force for the grinding grains, and to make the linear expansion coefficient of the core metal to 2.3X10<-5>/ deg.C or less. |
