Patent ID: 7559383
Filing Date: 2009-07-14
Classification: B23B,B28D,E21B

Abstract:
1. A solid hard material head for percussion drilling tool rotatable about a rotational axis (A) in a rotational direction (ω), the solid hard material head comprising at least one main bit ( 3 ) having a main cutting edge ( 4 ); and at least one auxiliary bit ( 5 ), circumferentially offset relative to the at least one main bit ( 3 ) and having an auxiliary cuffing edge ( 6 ) formed, at least piecewise, as a circular arc section ( 7 ) spaced from the rotational axis (A) radially inwardly and inclined in a radial direction, the auxiliary cutting edge ( 6 ) having a straight outer section ( 8 ) extending radially outwardly with respect to the circular arc section ( 7 ) and inclined in the radial direction with respect to a radius at an angle (α) of from 2° to 15°.