Retainer sleeve for a rotary bit

Abstract

A retainer sleeve for retaining a rotary bit includes a longitudinally slit cylindrical portion defining a longitudinal axis, and at least four circumferentially spaced tabs deformed generally radially inwardly from the cylindrical portion. The sleeve is formed from a sheet of spring steel having a thickness of at least 0.048 inches. Each tab comprises a connector section inclined from the cylindrical portion in a generally radially inward and longitudinally rearward direction and a keeper section extending rearwardly from a free end of the connector section. The keeper section includes a first flat surface facing the axis and oriented parallel thereto, and a second flat surface facing rearwardly and oriented perpendicularly to the axis.

1 . A cutting assembly comprising: 
 a bit defining a longitudinal axis of rotation and comprising a body including a head, and a shank projecting longitudinally rearwardly from the head, the bit further including a hard tip mounted at a front end of the head, the shank including a rear end and an annular groove disposed forwardly of the rear end and extending coaxially with the longitudinal axis, and a ring harder than the body and attached rearwardly of the hard-tip; and    a retainer sleeve including a longitudinally split cylindrical portion extending around the shank and extending substantially to the rear end, and at least four circumferentially spaced tabs deformed generally radially inwardly from the cylindrical portion and received in the annular groove, the sleeve formed of a sheet of spring steel having a thickness of at least 0.048 inches, each tab comprising a connector section inclined from the cylindrical portion in a generally radially inward and longitudinally rearward direction, and a keeper section extending rearwardly from a free end of the connector section, the keeper section including a first flat surface facing the axis and oriented parallel thereto and a second flat surface facing rearwardly and oriented perpendicularly to the axis.    
   
   
       2 . The cutter assembly according to  claim 1  wherein there are exactly four tabs.  
   
   
       3 . (canceled)  
   
   
       4 . (canceled)  
   
   
       5 . The cutter assembly according to  claim 2  wherein the four tabs are circumferentially spaced apart by an angle of about 86±5°.  
   
   
       6 . The cutter assembly according to  claim 1  wherein the bit includes a cylindrical flange rearward of the annular groove and having a diameter no greater than that of the shank.  
   
   
       7 . The cutter assembly according to  claim 6  wherein a rear end of the cylindrical flange is chamfered.