Shafted grinder and polishing tool

Abstract

A shafted grinder (1) includes a grinder (2) and a shaft (3) extending from the grinder (2). The grinder (2) includes a plurality of fiber bundles (22) of a plurality of inorganic filaments bundled together (21) bonded by a resin (23). When a stiffness of the shaft (3) is S, the shaft (3) satisfies the following conditional expression (A). When a region 30 mm from a rear end of the shaft (3) as a shank section (4) is fixed, a rear end of an outer peripheral end (2a) of the grinder (2) is pushed from a direction orthogonal to an axis (L), a push-in load is F (N), and an amount of displacement of a front end of the shaft 3 is δ (mm), the stiffness of the shaft is determined by using the following formula (B).0.4≤S≤100(A)S=F/δ(B)

1 . A shafted grinder comprising: a shaft having a shank section at a rear end; and a grinder having a rotationally symmetrical shape around an axis of the shaft and fixed to a front end of the shaft, the grinder having an outer peripheral end located on an outer peripheral side with respect to the shaft, the shank section being chucked into a hand-held rotary tool to polish a workpiece with the outer peripheral end of the grinder,
 wherein the grinder includes a plurality of grinding element bundles of a plurality of inorganic filaments bundled together and includes a resin bonding the grinding element bundles,   a natural frequency has a value that does not cause resonance during a polishing process when the following conditional expression is satisfied:
   0.4 ≤S ≤100
 
   
       where S is a stiffness of the shaft, and
 when a region 30 mm from the rear end of the shaft as the shank section is fixed to a jig and a rear end of the outer peripheral end of the grinder is pushed from a direction orthogonal to the axis, the stiffness of the shaft is determined by using the following formula:
     S=F/δ   
 
 
       where F (N) is a push-in load, and δ (mm) is an amount of displacement of the front end of the shaft. 
     
     
         2 . The shafted grinder according to  claim 1 , wherein a length dimension from the rear end of the shaft to the grinder is 50 mm or more. 
     
     
         3 . The shafted grinder according to  claim 1 , wherein the shaft has an outer diameter dimension of less than 6 mm. 
     
     
         4 . The shafted grinder according to  claim 1 , wherein the grinder weighs 0.8 g or less. 
     
     
         5 . The shafted grinder according to  claim 1 , further comprising a fixing mechanism configured to removably fix the grinder to the front end of the shaft. 
     
     
         6 . The shafted grinder according to  claim 1 , wherein the grinder is square or circular when viewed from a direction orthogonal to the axis. 
     
     
         7 . The shafted grinder according to  claim 1 , wherein the grinder has an outer diameter dimension of 3 mm or more, and an outer diameter dimension of the shank section and a thickness in a direction of the axis of the grinder are smaller than the outer diameter dimension of the grinder. 
     
     
         8 . The shafted grinder according to  claim 7 , wherein the grinder has a shape that tapers toward an outer peripheral side when viewed from a direction orthogonal to the axis. 
     
     
         9 . The shafted grinder according to  claim 7 , wherein the grinder is rectangular when viewed from a direction orthogonal to the axis. 
     
     
         10 . The shafted grinder according to  claim 1 , wherein a length dimension from the rear end of the shaft to the grinder exceeds 150 mm. 
     
     
         11 . A polishing tool comprising:
 the shafted grinder according to  claim 1 ; and   a rotary tool into which the shank section of the shafted grinder is chucked.