Degradation assembly shield
In one aspect of the present invention, a degradation assembly comprises a shank with a forward end and a rearward end, the rearward end being adapted for attachment to a driving mechanism, with a shield rotatably attached to the forward end of the shank. The shield comprises an underside adapted for rotatable attachment to the shank and an impact tip disposed on an end opposing the underside. A seal is disposed intermediate the shield and the shank.
1. A degradation assembly comprising:
a shank comprising a narrowing forward end and a rearward end, the rearward end being adapted to be retained in a holder attached to a driving mechanism; and
an underside of a shield rotatably connected to the forward end of the shank;
the shield also comprising a carbide bolster bonded to the impact tip at an end opposing the underside;
wherein the carbide bolster is disposed axially intermediate the impact tip and a steel portion of the shield along the assembly's central axis;
wherein a first and second cylindrical bearing surface on a large and smaller diameter of the forward end respectively is separated by a non-bearing, substantially conical portion of the forward end.
2. The assembly of claim 1 , wherein the reward end is substantially cylindrical and adapted to be press fit within the holder.
3. The assembly of claim 1 , wherein the shank is adapted to be rotationally stationary with respect to a driving mechanism in which the shank is secured and the shield is adapted to rotate around the shank.
4. The assembly of claim 1 , wherein the forward end is tapered.
5. The assembly of claim 1 , wherein the forward end comprises at least one step.
6. The assembly of claim 5 , wherein the forward portion of the at least one of the steps is adapted to be bear an impact load.
7. The assembly of claim 5 , wherein the diameter of the at least one of the steps comprises a bearing surface.
8. The assembly of claim 7 , wherein the bearing surface is adapted to engage a bearing element.
9. The assembly of claim 8 , wherein the bearing element is a roller bearing or a ball bearing.
10. The assembly of claim 1 , wherein the underside of the shield is lubricated.
11. The assembly of claim 1 , wherein the forward end comprise a load bearing surface.
12. The assembly of claim 1 , wherein a distal most surface is a load bearing surface.
13. The assembly of claim 12 , wherein a distal most surface of the forward end is adapted to contact the underside.
14. The assembly of claim 1 , wherein the distal most surface comprises a flat.
15. The assembly of claim 1 , wherein the shank comprises a radially extending flange below the shield.
16. The assembly of claim 15 , wherein a gap exist between the flange and the shield, when the shield is fully connected to the forward end.
17. The assembly of claim 1 , wherein the tip comprises a carbide substrate bonded to polycrystalline diamond.
18. The assembly of claim 1 , wherein the substrate is less than 10 mm thick.