Rock drill

Claim 1

A rock drill for percussion drilling of small diameter holes, comprising: a bit body including a front face, frontal button inserts, consisting of two in number and formed of hard metal, are mounted in said bit body and projecting forwardly beyond said front surface, and gauge button inserts, consisting of two in number and formed of hard metal, are mounted in gauge bores in said bit body and projecting forwardly beyond said front face, said gauge bores and said gauge button inserts being inclined at an angle relative to a longitudinal axis of the rock drill as viewed in a radial direction such that said gauge bores approach one another rearwardly, said gauge button inserts being arranged to define the diameter of the hole drilled by the rock drill, said frontal button inserts spaced radially inwardly of the diameter of the hole being drilled, the distance between said frontal button inserts being larger than the difference between the radial extension of said front face and the radial extension of said frontal button inserts, respectively, the smallest distance between the radially innermost portions of said gauge bores being smaller than said distance between said frontal button inserts, the smallest distance between the longitudinally outermost portions of said gauge bores being larger than said distance between said frontal button inserts, said frontal button inserts arranged on planar surface portions of said front face, said planar surface portions being coplanar, said gauge button inserts arranged on first and second surface portions, respectively, of said front face in such a way that a first imaginary line interconnecting the centers of the gauge button inserts is perpendicular to a second imaginary line interconnecting the centers of the frontal button inserts, said first and second surface portions being inclined relative to said planar surface portions, and said first and second imaginary lines intersecting each other at their middle points.