Super-hard cutter inserts and tools

1. A cutter insert assembly for a drill bit for boring into the earth, comprising a super-hard structure clampable to a support body by means of a clamp mechanism;

the clamp mechanism comprising opposed or opposable compression members connected or connectable by a tension member capable of sustaining a clamping force between the compression members when the cutter insert assembly is in a clamped condition, in which condition the compression members exert opposing compressive forces on the super-hard structure and the support body, operable to clamp the super-hard structure to the support body along an interface between the super-hard structure and the support body, the interface being non-planar and being configured to resist rotation or other displacement of the super-hard structure relative to the support body in the clamped condition, and in which condition the cutter insert assembly is self-supporting and capable of being mounted onto a drill bit body.

2. A cutter insert for a drill bit, consisting of a cutter insert assembly as claimed in claim 1 in the clamped condition.

3. A cutter insert as claimed in claim 2 , in which the tension member is disposed within an internal passage defined by the support body.

4. A cutter insert as claimed in claim 2 , in which the tension member is disposed within an internal passage defined cooperatively by the super-hard structure and the support body.

5. A cutter insert as claimed in claim 2 , in which the super-hard structure is releasably clamped to the support body by a releasable clamp mechanism.

6. A cutter insert as claimed in claim 2 , in which the clamp mechanism comprises an elongate longitudinal tension member having a pair of opposite ends, and a pair of opposing laterally projecting compression members each fixed or fastenable to a respective end.

7. A cutter insert as claimed in claim 2 , comprising two or more spaced-apart super-hard structures clamped to the support body by means of a clamp mechanism in which a compression member or intermediate compression member clamps the two or more super-hard structures simultaneously.

8. A cutter insert as claimed in claim 7 , the cutter insert having a rake face, wherein the intermediate compression member on the rake face of the cutter insert comprises a material having hardness of at least about 60 HRA Rockwell.

9. A cutter insert as claimed in claim 7 , in which the intermediate compression member comprises carbide material.

10. A cutter insert as claimed in claim 2 , the cutter insert having a rake face, wherein the compression member on the rake face of the cutter insert comprises a material having hardness of at least about 60 HRA Rockwell.

11. A cutter insert as claimed in claim 2 , in which the compression member comprises carbide material.

12. A cutter insert as claimed in claim 2 , the cutter insert having a rake face, and a wear resistant element comprising a super-hard material is attached to the cutter insert over the compression member on the rake face.

13. A cutter insert as claimed in claim 2 , in which the super-hard structure comprises PCD material.

14. A cutter insert as claimed in claim 13 , in which the PCD material has an interstitial mean free path in the range from about 0.05 micron to about 1.3 microns; and the standard deviation of the mean free path is in the range from about 0.05 micron to about 1.5 microns.

15. A cutter insert as claimed in claim 13 , in which the PCD material has a mean diamond grain contiguity of at least about 60 percent.

16. A cutter insert as claimed in claim 13 , in which the PCD material comprises diamond grains having mean size of at most about 20 microns.

17. A drill bit for boring into the earth, adapted for receiving and accommodating an embodiment of a cutter insert as claimed in claim 13 .

18. A cutter insert as claimed in claim 2 , in which the support body has an mean Young's modulus of at least about 60% that of the super-hard structure.