Patent ID: 7458139

Claim:
A tip dresser comprising a cutter, the tip dresser configured to grind a pair of electrode tips used for spot welding in a manner of approaching ends of a pair of the electrode tips to each other, the cutter comprising: a holder configured to be rotationally driven with a rotation center axis matched to an axial center of each of the mutually approached electrode tips; a cutter body retained by the holder to cut vicinities of the ends of electrode tips in case that the holder is rotated, the cutter body configured to cut the vicinities of the electrode tips in case of forward or reverse revolutions of the holder; and a discharge hole perforated between the cutter body and the holder along the rotation center axis to discharge cutting particles generated from grinding the ends of the electrode tips, wherein the cutter body further comprises a pair of accommodating concave parts provided to both edges in a length direction approximate to a direction of approaching a pair of the electrode tips to each other to accommodate the ends of the electrode tips in case of grinding a pair of the electrode tips aligned to oppose each other, respectively, wherein the cutter body further comprises a pair of recesses configuring a pair of the accommodating concave parts, respectively, wherein the cutter body further comprises a pair of plate type cutting blade parts, each having a cutting blade at one edge in a direction of a plate thickness becoming a circumferential edge of the corresponding recess, a pair of the plate type cutting blade parts assembled in an approximate cross shape to cross with each other in the vicinity of the rotation center axis, wherein a crossing point between the cutting blades is located on the rotation center axis, wherein if the holder is rotated in a forward direction, a portion of one of the cutting blades aligned to spread from the crossing point and a portion of the other cutting blade aligned distant from the crossing point cut the electrode tips, and wherein if the holder is rotated in a reverse direction, a portion of the other cutting blade aligned to spread from the crossing point and a portion of the former cutting blade aligned distant from the crossing point cut the electrode tips.