Patent ID: 8136817

Claim:
A motor with a cutting tool mounting hole, characterized in comprising: a cylindrical motor housing sealed at both ends in an axial direction thereof; a through-hole formed in a center of at least one end plate portion of the motor housing; a motor shaft in which one shaft end part thereof is exposed through the through-hole; a cutting tool mounting hole formed in a center portion of an end surface of the shaft end part in the motor shaft; a bearing for supporting the motor shaft in a manner that allows the motor shaft to rotate relative to the end plate portion, the bearing being installed between an inner periphery edge end of the through-hole in the end plate portion and an outer periphery surface portion of the shaft end part of the motor shaft; an annular contact seal having a flexible material for sealing a space between the inner periphery edge end of the through-hole and the outer periphery surface portion of the shaft end part in a position axially outside of the bearing; an annular seal plate having a rigid material fixed to the end plate portion in a position axially outside of the contact seal so as to conceal a space between the inner periphery edge end of the through-hole and the shaft end part; and a labyrinth seal for preventing ingress of cutting processing oil, the labyrinth seal being formed between the annular seal plate and the shaft end part of the motor shaft.