Grinding tool for grinding buttons of a rock drill bit, a grinding spindle and method for mounting the grinding cup on a grinding spindle

Abstract

A grinding tool for grinding buttons of a rock drill bit includes a spindle having a longitudinal axis of rotation, and a grinding cup mounted on the spindle by a tongue-and-socket connection. A fastener in the form of a coil spring secures the grinding cup to the spindle. The grinding cup can be inserted into the inside of, or around the exterior of, the coil spring. When the spindle is rotated in a working direction, the spring tightens against the grinding cup. To install or remove the grinding cup, the grinding cup is rotated relative to the spindle in a direction corresponding to the working direction, whereby engagement between the grinding cup and the coil spring becomes loosened.

What is claimed is:  
     
         1 . A grinding tool for grinding buttons of a rock drill bit comprising: 
 a spindle having a longitudinal axis of rotation;    a grinding cup mounted on the spindle by a tongue-and-socket connection which includes a cylindrical surface disposed on the grinding cup, the cylindrical surface being symmetrical with respect to the axis;    a vibration damper disposed between the grinding cup and the spindle;    a fastener for securing the grinding cup to the spindle, the fastener being attached to the spindle against axial displacement relative thereto, the fastener arranged to engage the cylindrical surface of the grinding cup to rotate the grinding cup when the spindle is rotated in a working direction, the fastener arranged to tighten a grip on the grinding cup when the spindle is rotated in the working direction during a grinding operation, and to permit rotation of the grinding head relative to the spindle in a direction corresponding to the working direction to loosen the grinding head for insertion and removal thereof.    
     
     
         2 . The grinding tool according to  claim 1  wherein the fastener comprises a coil spring.  
     
     
         3 . The grinding tool according to  claim 2  wherein the coil spring defines a sole means of transferring rotation from the spindle to the grinding head.  
     
     
         4 . The grinding tool according to  claim 3  wherein one end of the spring is secured against axial movement and rotational movement relative to the spindle.  
     
     
         5 . The grinding tool according to  claim 3  wherein the spring is situated inside of the cylindrical surface.  
     
     
         6 . The grinding tool according to  claim 3  wherein the spring is situated outside of the cylindrical surface.  
     
     
         7 . A grinding cup for grinding buttons of a rock drill bit, the grinding cup having a body defining an axis of rotation and including a forward wear part and a rear shank, a flush channel extending through the shank, the shank including a cylindrical surface arranged symmetrically relative to the axis and defining a sole means of receiving a rotary drive torque during a grinding operation.  
     
     
         8 . The grinding cup according to  claim 7  wherein the body further comprises an intermediate portion which connects the shank to the wear part, the wear part including flush channels oriented eccentrically relative to the axis and communicating with the flush channel that extends through the shank.  
     
     
         9 . Apparatus for holding an insert-grinding cup, comprising a grinding spindle defining an axis of rotation and including a cylindrical surface at one end thereof adapted to receive a grinding cup, and a fastener for securing a grinding cup, the fastener disposed against the cylindrical surface and attached against axial movement relative to the spindle, the fastener arranged to permit movement of a grinding cup relative to the spindle in a direction corresponding to a working direction of the spindle.  
     
     
         10 . The apparatus according to  claim 9  wherein the fastener comprises a coil spring which constitutes a sole means of transferring rotation from the spindle to a grinding cup.  
     
     
         11 . The apparatus according to  claim 10  wherein the cylindrical surface comprises an inner surface of a recess formed in the spindle, the recess adapted to receive the coil spring and a grinding cup, the spring being radially contractible to hold a grinding cup.  
     
     
         12 . The apparatus according to  claim 10  wherein the cylindrical surface comprises an outer surface of a projection of the spindle, the projection adapted to receive the coil spring and a grinding cup, the spring being radially expandible to hold a grinding cup.  
     
     
         13 . The apparatus according to  claim 10  wherein one axial end of the spring is secured to the spindle against rotation and axial movement relative thereto, and an opposite axial end of the spring is free.  
     
     
         14 . A method for mounting a grinding cup on a grinding spindle for grinding buttons of a rock drill bit, the grinding spindle including a first cylindrical surface, the grinding cup including a forward wear part and a rear shank having a second cylindrical surface connectable to the first cylindrical surface, and a coil spring fastener for interconnecting the first and second cylindrical surfaces, the method comprising the steps of: 
 A) attaching the coil spring fastener to the grinding spindle such that the fastener is immovable relative thereto in the axial direction;    B) positioning a vibration-damping element between the spindle and the grinding cup; and    C) moving the grinding cup axially into engagement with the spindle while rotating the grinding cup relative to the spindle in a direction corresponding to a working direction of the spindle to elastically loosen the coil spring fastener and permit the grinding cup to be axially inserted onto the spindle.    
     
     
         15 . The method according to  claim 14  wherein step A is performed prior to step B.  
     
     
         16 . The method according to  claim 14  wherein step B is performed prior to step A.