Patent ID: 8899888

Claim:
A tip dresser comprising: a plate-shaped cutter that has cutting blades having shapes corresponding to the external shapes of substantially the halves of the tip end portions on one side with respect to the central axis of a pair of electrode tips on both edges in the width direction of the tip end sides disposed on the central axis side at the edge of the surface side being one side in the thickness direction so as to cut tip end faces of the tip end portions of the pair of electrode tips opposed to each other and expanding portions expanding from the tip end faces simultaneously, and an attaching hole perforating through the cutter on a base portion side away from the portion between the two cutting blades; a holder that has receiving surfaces recessed so as to receive the tip end portions of the pair of electrode tips on both end face sides, and an attaching surface which is a part of a discharging recess for discharging shavings formed to penetrate along a rotation central axis at the time of cutting that matches the central axis, and to which the cutter is attached by putting the back side that is opposite to the surface side and becomes the cutting blade side of the cutter on the attaching surface and screwing an attaching screw inserted through the attaching hole; and a rotary drive portion that holds rotatably the holder to which the cutter is attached, where a breaker for discharging shavings is disposed on the surface side of the cutter, wherein the breaker is formed to have a plate shape having a through hole through which the attaching screw is inserted so that the breaker is tightened together with the cutter by the attaching screw, and includes an attaching, substrate portion that extends in substantially a plane shape from a peripheral edge of the insertion hole to be pressed by the head portion of the attaching screw at the time of tightening, and inclined guide surfaces that are disposed on the outer peripheral edge of the breaker around the attaching substrate portion, and are disposed near the cutting blades so as to bulge from flat portions of the surface side while inclining from the flat portions and guide the shavings produced from the portions of the cutting blades to separate the shavings away from the surface side.