| 摘要 |
A lathe which rotates a workpiece on centers about an axis, with one end face of the workpiece directed axially backward and having a radially outer periphery generally centered on the axis, has a drive formed by a body axially adjacent the workpiece end face and rotatable about the axis, a motor for rotating the body about the axis, and a face plate rotationally fixed on the body and lying between same and the workpiece end face. A plurality of sets of drive formations or teeth are fixed on the face plate and directed axially forward toward the workpiece. Each set is comprised of a respective plurality of the formations angularly equispaced about the axis and radially equispaced therefrom by a respective radius different from the radius between the formations of any of the other sets and the axis. The formations of each set have axially inner edges lying in a respective plane perpendicular to the axis and offset from the planes of the other sets and the plane of the set with the smallest radius is axially rearmost, that is furthest from the workpiece, while the plane of the set of the largest radius is axially foremost and the remaining planes are graduated therebetween. The face plate is urged axially forward toward the workpiece end face for pressing one set of formations axially inward against the workpiece and rotationally coupling it to the face plate and body. The one set engaging the workpiece is the set having the largest radius that is generally equal to or smaller than the radius of the workpiece periphery. |
