Surgical bur with anti-chatter flute geometry

Abstract

A surgical bur ( 20 ) including a shaft with a bur head. A number of flutes are formed on the bur head. Each flute has a cutting edge ( 54 ). The flutes are formed so that some of the flutes having cutting edges emerge from the bur head at locations relatively close to the distal end tip of the head. Still other flutes are formed so as to have cutting edges that start, extend proximally rearward, from locations that are, spaced proximal from the distal end tip.

1 . A surgical bur comprising:
 an elongated shaft having opposed proximal and distal ends;   a coupling feature associated with the proximal end of the shaft, the coupling featured shaped to engage a drive unit of a surgical handpiece so that the handpiece can rotate the shaft;   a bur head attached to the distal end of the shaft, the bur head having:
 a body with a distal end tip; 
 a first set of flutes, each said flute having a cutting edge and said first set of flutes emerging from said flute head body so that the cutting edge of said first set of flutes emerge from said bur head so as to have cutting edges that start at a first location proximal from the bur head distal end tip; and 
 a second set of flutes, each said flute having a cutting edge, wherein said second set of flutes emerge from said flute body and are interleaved with the flutes of said first set of flutes and said second set of flutes are interleaved with said first flutes end and are shaped to have cutting edges that start at a second location proximal from the bur head distal end tip, the second location being proximally spaced from the first location. 
   
     
     
         2 . The surgical bur of  claim 1 , wherein:
 each said flute is formed with a rake surface and a clearance surface that meets to form the cutting edge of said flute;   each said flute of said second set of flutes is formed to have chamfered surfaces that extends proximally from said bur head distal end tip between the flute rake surface and the clearance surface so that the cutting edge of the said flute does not extend forward of the chamfer surface.   
     
     
         3 . The surgical bur of  claim 1 , wherein the bur head is constructed so that the flutes forming the first and second set of flutes alternate with each other around the circumference of the bur head. 
     
     
         4 . The surgical bur of  claim 1  wherein: the flutes forming the first and second flutes are shaped so that the cutting edges thereof have a common proximal end terminus along the length of the bur head. 
     
     
         5 . The surgical bur of  claim 1  wherein the bur head body is formed to have a third set of flutes that have cutting edges wherein said third set of flutes are shaped so that the cutting edges of said flutes start at a third location proximal from the bur head, the third location being proximally spaced from the second location. 
     
     
         6 . The surgical bur of  claim 1 , wherein the first set of flutes are arranged symmetrically around the bur head and the second set of flutes are arranged symmetrically around the bur head. 
     
     
         7 . The surgical bur of  claim 1 , wherein the bur head has shape selected from one of the following: acorn style; spherical; barrel; egg; pear; and drum. 
     
     
         8 . A surgical bur, said bur van elongated shaft having opposed proximal and distal ends;
 a coupling feature associated with the proximal end of the shaft, the coupling featured shaped to engage a drive unit of a surgical handpiece so that the handpiece can rotate the shaft;   a bur head attached to the distal end of the shaft, the bur head having: a body with a distal end tip; and a plurality of flutes that emerge from said body at locations proximal to the distal end tip, wherein each said flute has a rake surface and a clearance surface that meet to define a cutting edge wherein:
 there is a first set of flutes each flute of said first set of flute emerging from said bur head so as to have cutting edges that start at a first location proximal from the bur head distal end tip; and 
 there is a second set of flutes, said first and second set flutes being interleaved with each other around said bur head, each flute of said second set of flutes also having a chamfer surface that extends proximally from the bur head distal end tip over the rake and clearance surfaces of said flute so that the flute cutting edges originate at the chamfer surface so that the cutting edges of the second set of flutes start at a second location proximal from the bur head distal end tip, the second location being spaced proximally relative to the first location. 
   
     
     
         9 . The surgical bur of  claim 8 , wherein said first set of flutes comprises a single pair of flutes that are symmetrically to each other around the bur head distal end tip. 
     
     
         10 . The surgical bur of  claim 8 , wherein:
 said first set of flutes comprises a single pair of flutes that are symmetrically to each other around the bur head distal end tip so that said first set flutes are separated by an arcuate space; and   in the arcuate space between each said flute of the said first pair of flutes there is at least one flute of the second set of flutes; and   between each said flute of the first pair of flutes and the adjacent flute of the second pair of flutes there is a flute from a third set of flutes, each flute of said third set of flutes having a chamfer surface that extends over the rake and clearance surfaces of said flute so that the flute cutting edges originate at the chamfer surface so that the cutting edges of the third set of flutes start at a third location proximal from the bur head distal end tip, the second location being spaced proximally relative to the first location.   
     
     
         11 . A surgical bur comprising:
 an elongated shaft having opposed proximal and distal ends;   a coupling feature associated with the proximal end of the shaft, the coupling featured shaped to engage a drive unit of a surgical handpiece so that the handpiece can rotate the shaft;   a bur head attached to the distal end of the shaft, the bur head having a body and a distal end and a plurality of arcuately spaced apart flutes that emerge from the body, each flute having a cutting edge wherein the bur head is formed so that the there is a first pitch angle between a first pair of adjacent flutes and a second pitch angle between a second pair of adjacent flutes ( 176 ,  178 )   
     
     
         12 . The surgical bur of  claim 11 , wherein the bur head is formed so that pitch angles between adjacent pairs of flutes is different.