Grinder

Abstract

A grinder includes a lock mechanism, attached to a bearing box, that inhibits detachment/rotation of a cylindrical portion of a wheel cover. The lock mechanism includes a ring-shaped lock member, with a larger diameter than the cylindrical portion, that surrounds the bearing box and has a front side inner edge protruding engagement hook. The lock member can slide between a front-side lock released position at which the engagement hook is separated from the bearing box to the front side and the cylindrical portion can be attached/detached to/from the bearing box, and a rear-side locked position at which the engagement hook passes through the cylindrical portion that surrounds the bearing box and engages with a bearing box outer periphery such that a front portion is contained within a gear housing in a plan view. The lock mechanism also includes a torsion spring that urges the lock member to the locked position.

1 . A grinder comprising:
 a motor housing that accommodates a motor;   a front housing that is connected to a front side of the motor housing;   a spindle that is supported in a vertical direction by the front housing, the spindle having a lower end that protrudes downward and to which a disc-shaped tool can be attached;   a bearing unit, having a circular external shape, that supports the spindle at a lower portion of the front housing;   a protective cover, attached to the bearing unit, including a cover portion that covers the disc-shaped tool from above, and a cylindrical portion connecting to an upper edge of the cover portion and surrounding the bearing unit; and   a lock mechanism, provided on the bearing unit, that inhibits the surrounding cylindrical portion from detaching and rotating, wherein   the lock mechanism includes:
 a lock member that has a ring-shape with a larger diameter than the cylindrical portion and that surrounds the bearing unit and has a protruding engagement hook provided in a front side inner edge, the lock member being capable of sliding between a front-side lock released position at which the cylindrical portion can be attached to or detached from the bearing unit as a result of the engagement hook separating away from the bearing unit to the front side, and a rear side locked position at which the engagement hook passes through the cylindrical portion that surrounds the bearing unit and engages with an outer periphery of the bearing unit such that, at the least, a front portion of the lock member is contained within the front housing when seen in a plan view; and 
 an urging unit for urging the lock member to the locked position. 
   
     
     
         2 . The grinder according to  claim 1 , wherein the urging unit is a torsion spring which is positioned in a left and right direction at one of an upper side and a lower side of the lock member, and which has end portions that engage with the lock member. 
     
     
         3 . The grinder according to  claim 1 , wherein an elastic member is embedded in the bearing unit, the elastic member protruding from an outer peripheral surface of the bearing unit and forcibly pushing against an inner peripheral surface of the surrounding cylindrical portion. 
     
     
         4 . The grinder according to  claim 3 , wherein the elastic member is a rubber pin that is forcibly inserted in an insertion groove formed in the outer peripheral surface of the bearing unit. 
     
     
         5 . The grinder according to  claim 1 , wherein a regulating member is provided in the lock mechanism, the regulating member being operable to move between a regulation position at which the regulating member engages with the lock member in the lock released position so as to regulate sliding from the lock released position, and a regulation released position at which engagement of the regulating member and the lock member is released such that sliding of the lock member is permitted. 
     
     
         6 . The grinder according to  claim 5 , wherein the regulating member is a lock button that is urged to the regulation position by a coil spring. 
     
     
         7 . The grinder according to  claim 1 , wherein the lock member is a frame-shaped body having a front side that is round and a rear side that is rectangular. 
     
     
         8 . The grinder according to  claim 7 , wherein a base is assembled to the bearing unit, the base including guide portions having left and right side surfaces that are formed to extend in a front-rear direction in line with a direction tangential to the bearing unit, and the lock member surrounds the bearing unit with the rear side of the lock member being fitted to the guide portions such that the lock member can only slide in the front-rear direction. 
     
     
         9 . The grinder according to  claim 1 , wherein the engagement hook is provided as a pair of engagement hooks. 
     
     
         10 . The grinder according to  claim 7 , wherein curved protrusions are formed in left and right outside surfaces of the lock member and increasingly protrude to an outer side as the curved protrusions extend in the forward direction. 
     
     
         11 . The grinder according to  claim 1 , wherein the cover portion has a semi circular shape when seen in a plan view, the semi-circular shape covering a rear half portion of the disc shaped tool. 
     
     
         12 . The grinder according to  claim 11 , wherein a groove that runs parallel to an axial direction is formed in the outer peripheral surface of the bearing unit, and a protrusion is formed in the cylindrical portion, the protrusion being formed to be in alignment with the groove when the cover portion is position at the rear side.