Patent ID: 7527110
Filing Date: 2009-05-05
Classification: E21B

Abstract:
1. A percussive drill bit comprising: a working face opposite a shank end; the working face comprising a central jack insert and a plurality of peripheral inserts extending from the working face, the central jack insert being concentric with an axis of rotation of the drill bit; the ends of the plurality of peripheral inserts forming an impacting plane; the central jack insert being disposed within a recessed portion of the working face and comprising an end extending between the working face and the impacting plane; wherein a bit skirt is located intermediate the working face and the shank end and the skirt comprises a plurality of shearing elements, and wherein the central jack insert comprises a hardness greater than at least one of the peripheral inserts; and wherein the working face further comprises a washer of at least 63 HRc disposed around the diameter of at least one of the inserts, washer being disposed within a recess formed in the working face.