Variable Angle Cutting Bit Retaining Assembly

Abstract

A cutting bit retaining assembly for mounting a cutting bit at a cutting machine. The assembly includes a holder body to receive a shank like adaptor with a cutting bit demountable at one end of the adaptor. An annular shoulder is provided at the cutting bit mounting end of the adaptor having a wedge configuration, so as to mount the cutting bit at a tilted angle relative to the shank of the adaptor to provide a desired cutting bit attack angle.

1 . A cutting bit retaining assembly for mounting a cutting bit at a cutting machine, the assembly comprising:
 a holder body having a bore extending in a direction between a forward end and a rearward end of the body, an end surface being positioned at an entrance of the bore;   an elongate bit shaft having a central longitudinal axis and configured to extend axially into the bore to mount the shaft at the holder body;   the shaft terminated at one end by a male projection configured to be received within a female cavity formed within a cutting bit attachable to the shaft, the projection being configured to releasably retain the bit at the shaft via a retainer;   a shoulder projecting radially outward from the shaft at an axial junction of the male projection and a first end of the shaft, an underside surface of the shoulder being configured to mate in touching or near touching contact with the end surface to support mounting of the shaft at the holder body; and   a central longitudinal axis of the male projection aligned transverse to the longitudinal axis of the shaft such that the male projection is fixed at a generally tilted angle relative to the shaft so as to mount the bit at a predetermined attack angle relative to the holder body.   
     
     
         2 . The assembly as claimed in  claim 1 , wherein the shoulder is a wedge having an axially thicker part relative to an axially thinner part, the underside surface being provided at an underside of the shoulder. 
     
     
         3 . The assembly as claimed in  claim 2 , wherein the underside surface and the end surface are substantially planar to mate in close touching contact. 
     
     
         4 . The assembly as claimed in  claim 1 , wherein the shoulder includes a forward facing surface to mate with a rearward facing surface of the bit. 
     
     
         5 . The assembly as claimed in  claim 1 , wherein the angle that the longitudinal axis of the male projection is transverse to the longitudinal axis of the shaft is in a range 1 to 60°. 
     
     
         6 . The assembly as claimed in claim wherein the range of the angle is 2 to 20°. 
     
     
         7 . The assembly as claimed in  claim 1  wherein the shaft or the shoulder includes a first locking member and the holder body includes a second locking member, the first and second members being configured to engage and prevent the shaft from rotating within the bore. 
     
     
         8 . The assembly as claimed in  claim 7 , wherein the first member includes a male abutment projecting from the shaft or the shoulder and the second member includes a recess to at least partially receive the first member. 
     
     
         9 . The assembly as claimed in  claim 1 , wherein the shoulder is formed integrally with the shaft. 
     
     
         10 . The assembly as claimed in  claim 1 , wherein an axially rearward region of the male projection has a concave or tapered annular surface extending axially forward from the shoulder to mate in close touching contact with a convex or tapered surface within the cavity of the bit. 
     
     
         11 . The assembly as claimed in  claim 1 , wherein the shaft has a length sufficient to extend axially through the bore such that a rearward second end of the shaft projects from the rearward end of holder body. 
     
     
         12 . The assembly as claimed in  claim 1 , wherein an axial length of the male projection is substantially in a range ¼ to ½ of an axial length of the shaft that extends rearwardly from the shoulder. 
     
     
         13 . The assembly as claimed in  claim 1 , wherein the retainer includes a ring and the projection includes an indented channel to at least partially receive the ring such that ring is accommodated radially between the projection and the bit. 
     
     
         14 . A cutting bit assembly for mounting at a cutting machine comprising:
 a retaining assembly including a holder body having a bore extending in a direction between a forward end and a rearward end of the body, an end surface being positioned at an entrance of the bore; an elongate bit shaft having a central longitudinal axis and configured to extend axially into the bore to mount the shaft at the holder body, the shaft terminating at one end by a male projection configured to be received within a female cavity formed within a cutting bit attachable to the shaft, the projection being configured to releasably retain the bit at the shaft via a retainer; a shoulder projecting radially outward from the shaft at an axial junction of the male projection and a first end of the shaft, an underside surface of the shoulder being configured to mate in touching or near touching contact with the end surface to support mounting of the shaft at the holder body; and a central longitudinal axis of the male projection aligned transverse to the longitudinal axis of the shaft such that the male projection is fixed at a generally tilted angle relative to the shaft so as to mount the bit at a predetermined attack angle relative to the holder body; and   a cutting bit having a cutting tip at first end and a cavity projecting inwardly from a second end, the bit being releasably mounted at the shaft via mating of the male projection within the cavity.   
     
     
         15 . The assembly as claimed in  claim 14 , wherein the shoulder is annular to provide an annular underside surface. 
     
     
         16 . The assembly as claimed in  claim 11 , further comprising a retainer mountable at or towards the second end of the shaft to releasably retain the shaft at the holder body.