Cutting burr shank configuration
A cutting burr that includes a pair of axially spaced diamond-shaped portions designed to be keyed into a spindle of a locking mechanism of a high speed surgical drilling instrument and adapted to fit into a single pawl thereof to lock said cutting burr in place so as to prevent axial movement thereof and provide concentric rotation of said cutting burr without any wobbling. The orientation of both portions may be identical with respect to a center plan and diamond shape in the portion at the proximal end of the shank of the cutting tool may be larger than the intermediately located diamond shape of the other portion. The apexes of the facets of the six-sided diamond shape may be disposed below the surface of the shank of the cutting burr.
1. A cutting burr having a shank with an engagement end at a proximal end of the shank adapted to be received by a surgical drill, comprising:
a first diamond-shaped portion formed at the proximal end of the shank and having first side edges, the first diamond-shaped portion having a first pair of facets that meet at a first apex and an opposing second pair of facets, wherein the first diamond-shaped portion comprises a flanged portion with tapered surfaces; and
a second diamond-shaped portion axially spaced along a shaft of the shank from the first diamond-shaped portion and having second side edges, the second diamond-shaped portion having a third pair of facets that meet at a second apex and an opposing fourth pair of facets, wherein the second diamond-shaped portion comprises a flanged portion;
wherein a back wall of the flanged portion of the first diamond-shaped portion is perpendicular to a center line of the shank and faces a front wall of the flanged portion of the second diamond-shaped portion, the front wall being tapered from one of the third pair of facets or the fourth pair of facets to an outside surface of the shank;
wherein the first diamond-shaped portion is adapted to be inserted into a complementary shaped mating recess of the surgical drill, and
wherein the second diamond-shaped portion is adapted to mate with a complementary locking pawl of the surgical drill.
2. The cutting burr of claim 1 , wherein the first diamond-shaped portion and the second diamond-shaped portion are each formed having six sides, and wherein the first side edges and second side edges are arched having a radius of curvature of an outside diameter of the shank.
3. The cutting burr of claim 1 , wherein each of the facets has a substantially flat surface.
4. The cutting burr of claim 1 , wherein the first pair of facets and the second pair of facets are symmetrical about a center plane of the shank.
5. The cutting burr of claim 1 , wherein diametrical dimensions of vertices of the first diamond-shaped portion and the second diamond-shaped portion is less than a diameter of the shank.
6. The cutting burr of claim 1 , wherein the shank includes an annular groove.
7. The cutting burr of claim 1 , wherein the third pair of facets are formed at a predetermined angle to receive the locking pawl having a complementary shape to that of the third pair of facets.
8. The cutting burr of claim 7 , wherein the complementary shape is generally a V-shape.
9. The cutting burr of claim 1 , wherein the fourth pair of facets of the second diamond-shaped portion are adapted to be engaged by a detent pawl of the surgical drill, wherein the detent pawl is generally hill-shaped to partially fit into the second diamond-shaped portion on an opposite side of the locking pawl.
10. The cutting burr of claim 1 , wherein the first diamond-shaped portion is adapted to accept rotational engagement forces of the surgical drill from the mating recess, and wherein the second diamond-shaped portion in cooperation with the locking pawl provides for axial locking of the cutting burr.
11. The cutting burr of claim 10 , wherein the first pair of facets and the second pair of facets provide positive engagement surfaces within the mating recess in both clockwise and counter-clockwise rotational directions of the surgical drill.
12. The cutting burr of claim 1 , wherein the back wall is adapted to be engaged by an engagement end of the locking pawl.
13. The cutting burr of claim 1 , wherein the tapered front wall facilitates the engagement of the locking pawl into the second diamond-shaped portion.
14. The cutting burr of claim 1 , wherein the first diamond-shaped portion and the second diamond-shaped portion are different sizes.
15. The cutting burr of claim 14 , wherein a width of each of the facets of the second diamond-shaped portion is approximately 0.046″, wherein the third pair of facets and the fourth pair of facets are formed at approximately an angle of 47°, and wherein a length of the second diamond-shaped portion is approximately 0.068″.
16. The cutting burr of claim 14 , wherein a width of each of the facets of the first diamond-shaped portion is approximately 0.065″, and wherein a length between the proximal end and a back wall of first diamond-shaped portion is approximately 0.149″.
17. The cutting burr of claim 14 , wherein a width of an axial space between the first diamond-shaped portion and the second diamond-shaped portion is approximately 0.029″.
18. The cutting burr of claim 1 , wherein the first diamond-shaped portion and the second diamond-shaped portion are in axial alignment and are oriented in a parallel relationship.
19. The cutting burr of claim 18 , wherein the first apex and the second apex are in axial alignment.