Patent ID: 6918455

Claim:
A percussion drill bit for percussive drilling in a formation, comprising: (a) a bit head for percussive impact against the formation; (b) at least a first plurality of first inserts and a second plurality of second inserts extending from the bit head; (c) each of the first inserts having a first base portion that is not superhard mounted to the bit head and a first exposed portion extending from the bit head, the first exposed portion having a first profile and a first contact area; (d) each of the second inserts having a second base portion mounted to the bit head and a second exposed portion extending from the bit head, each of the second exposed portions having a second profile that is appreciably different from the first profile and a second contact area that is appreciably different from the first contact area of the first exposed portion, at least some of the second exposed portions enhanced with a superhard material, wherein the bit head defines a first plurality of first cavities in which the first plurality of first inserts are disposed, and a second plurality of second cavities in which the second plurality of second inserts are disposed, wherein the depth of the second cavities is greater than the depth of the first cavities such that base planes of two adjacent cavities that are selected one each from the first cavities and the second cavities do not intercept in a bit section between the two adjacent cavities; and (e) wherein the bit head has a periphery with a gage row having at least some of the second inserts located therein, and the gage row further comprises at least some of the first inserts.