Abstract: This invention relates to a vibration dampening grinding cup for handheld grinding machines for the grinding of hard metal buttons on button bits, comprising a grinding head and a shaft made with a common axial channel for cooling medium, which distinguishes in that the shaft is formed with a driver part at its free end and an annular groove between this part and the grinding head, and that a bushing of rubber is arranged on the shaft adjacent to the grinding head, and a holder for such a grinding cup, which distinguishes in that it comprises a substantially cylindrical socket with an axial through channel, whose one end is connected with the rotor of the handheld grinding machine and through the other end of which shaft of the grinding cup is intended to be entered for installing the driver part of the shaft in a correspondingly formed driving part of the channel of the socket and to be fastened through introduction of balls situated in holes in the wall of the socket at the other end of the socket into the

Abstract: An arrangement in hand-held grinding machines intended for grinding the buttons of button drill-bits and provided with a driven spindle which carries a grinding disk. The grinding disk presents a profiled groove for shaping respective buttons of the bit to their intended tip profile. In order to enable buttons to be ground quickly and effectively with the aid of a hand-held grinding machine without needing to rotate the button to be ground about its own longitudinal axis, there is provided a spring-steel guide-spring which is mounted fixedly in relation to the grinding disk and which presents on both sides of the disk (4) obliquely and inwardly extending fingers which are intended to engage the button to be ground when the grinding disk is brought into engagement with the button.

Abstract: An abrasive wheel for grinding the cutting pins of a button-type drilling bit in a grinding machine of the kind provided with a rotatable holder for fixating the pins of the bit in a grinding position and for rotating thus fixated pins. The machine also includes a spindle on which the abrasive wheel can be mounted in a given position. The spindle/holder is linearly movable in a plane which extends through and is contained by the respective rotational axes of the holder and the spindle and in a direction parallel with the rotational axis of the spindle. The abrasive wheel includes circular flange parts which embrace a profiled groove therebetween. To enable cutting pins to be ground to an obtuse tip-profiled shape with the aid of such an abrasive wheel, the profiled groove, when seen in cross-section, is formed symmetrically around a line which intersects the rotational axis of the abrasive wheel at an angle whose complementary angle is equal to the angle of inclination of the spindle.

Abstract: An abrasive wheel for grinding a drill bit of the kind having hard metal inserts set into a head includes two circular flange portions and a circumferential profile groove between the flange portions corresponding to the end profile intended for drill bit insert. The flange portions (7, 8) and interposed profile groove (10) are included in a first abrasive wheel body (3) having a covering coating of abrasive agent such as diamond, adapted to grind hard metal. At least one other abrasive wheel body (4), is nonrotatable and concentrically connected to one flange portion (7 or 8) of the first abrasive wheel body and, at a greater radial distance from the rotary shaft of the abrasive wheel than the adjacent flange portion of the first abrasive wheel body, has a circumferential end portion (15) having a substantially round cross-sectional form and a coating (16) of an abrasive agent, e.g. boron nitride, adapted to grind the material in the drill bit head.