Abstract: A punching device is provided which includes a plurality of punching units arranged in a side-by-side fashion on a substantially horizontal working surface. The device includes a plurality of punches and dies of different shaped, and a moving assembly, for supporting a holder frame, which moves a workpiece along both X- and Y-axes on a working table. A control unit is provided for inputting punching positions on the workpiece as well as the shape(s) of the holes to be punched, as well as for controlling operation of the moving assembly and punching units in response to inputted data, and for moving the punching positions of the workpiece below the desired punching units to perform punching operations. The punching units each comprises a substantially -shaped supporting member in which a piston is provided for moving a punch upwardly and downwardly. The punch is provided in one arm of the -shaped support member, with a corresponding die in a lower portion of the support member.

Abstract: The improved dental handpiece comprises an operating sleeve slidably mounted on an outer circumference of the rotor shaft, said operating sleeve being formed with a flange, a spring for normally biasing the operating sleeve frontwardly, an operation collar threadedly engaged with an outer circumference of the outer cylinder, a pusher ring interposed between an inner surface of the operation collar and a front surface of the flange of the operating sleeve, a cylindrical portion formed at a front portion of the rotor shaft for receiving the main shaft of the working tool, a plurality of key holes formed through a wall of the cylindrical portion at a position opposed to an inner surface of the operating sleeve in such a manner as to be arranged at equal intervals on the same circumference, each of said key holes having a segment-like shape in cross section, a plurality of chuck keys engaged in the key holes, each of said chuck keys having a shape corresponding to the shape of each key hole in such a manner that