Hard metal insert for a drill bit for percussion drilling and method for grinding a hard metal insert

摘要

A hard metal insert for a drill bit for percussion drilling. A wear part includes a cap including a wear surface. A mount includes a cylindrical part having a cross-sectional area and a diameter. The cap includes a front part with an extension along an axis of symmetry of the insert from a first point on the wear surface to a second point in the cap. The front part includes a volume between a first plane intersecting the axis at the first point and a second plane intersecting the axis at the second point. The volume is ≧0.6 times a cross-sectional area of the front part in the second plane times a distance along the axis between the first and second points. A diameter of the front part in the second plane is ≧0.5 times the mount diameter and ≦0.6 times the mount diameter.

主权项

1. A hard metal insert for a drill bit for percussion drilling, the insert comprising:
a wear part comprising a cap comprising a wear surface, wherein the wear part is rotationally symmetrical about a longitudinal axis of the wear part and the cap and wear surface extend entirely around the longitudinal axis; and a mount comprising a cylindrical part having a cross-sectional area and a diameter; wherein the cap comprises a front part with an extension along an axis of symmetry of the insert from a first point on the wear surface of the cap to a second point in the cap, wherein the front part comprises a volume between a first plane, which intersects at right angle to the axis of symmetry at the first point and a second plane, which intersects at right angle to the axis of symmetry at the second point, wherein the volume is greater than or equal to 0.6 times a cross-sectional area of the front part in the second plane times a distance along the axis of symmetry between the first point and the second point, wherein a diameter of the front part in the second plane is greater than or equal to 0.5 times the diameter of the mount and less than or equal to 0.6 times the diameter of the mount, and wherein a height of the extension is less than half the diameter of the extension.