A machine tool includes a main shaft unit; a polishing head for processing a workpiece; and an unnecessary byproduct leakage preventing unit for preventing leakage of abrasive resulting from processing at or around a part of the workpiece, the part being processed, and wherein the unnecessary byproduct leakage preventing unit includes a cover provided separately from the polishing head, the cover having a structure that is open in three directions and that has walls in another three directions such that a protection space where to hold a part of the workpiece is defined, the cover for receiving the abrasive, and a movement mechanism for moving the cover so as to stay apart from the workpiece while the workpiece is not being processed and so as to have a part of the workpiece held in the protection space while the workpiece is being processed.

A grinding apparatus grinds a workpiece by rotating the workpiece held by main spindles and a grinding wheel held by a wheel spindle, and by relatively moving the grinding wheel toward and away from the workpiece. The grinding apparatus includes a first detection unit that detects a rotational phase of the workpiece; a second detection unit that detects a grinding resistance moment at a grinding point between the grinding wheel and the workpiece, or detects a drive current of a rotary drive unit of the workpiece or a rotary drive unit of the grinding wheel; a storage unit that stores the grinding resistance moment or the drive current in a manner associated with the rotational phase; and a determination unit that determines a slip between the workpiece and the main spindles based on the grinding resistance moment or the drive current at a current rotational phase, and on the grinding resistance moment or the drive current at the same phase as the current rotational phase of a previous time.

A cutting tool includes: a cutting part including a cutting edge having a linear shape; and a fitted part including a fixed section to which the cutting part is fixed, and a fitted part body to be fitted to a cutting device. The cutting edge is located perpendicularly to a virtual line passing through a central axis of the fitted part body, on a plane that is perpendicular to the central axis of the fitted part body. A center of the cutting edge in its longitudinal direction is located on the virtual line.

The described embodiments relate generally to lapping operations and related systems and apparatuses. Various embodiments of lapping tables are described for applying a lapping operation to a non-planar surface of a workpiece. For example, methods and apparatus are described which allow a lapping operation to be applied to a curved outer surface portion of a cylindrical workpiece. Lapping of non-planar outer surfaces of workpieces is conducted by rotating the workpieces during the lapping operations.

Through the following steps (a) and (b), the side surface of a grinding object is ground to manufacture a ground product having a smaller diameter than that of the grinding object. In the step (a), a cup type grinding stone is disposed such that the central axis is parallel offset from a state where the central axis is orthogonal to the central axis of the grinding object. In the step (b), the cup type grinding stone is axially rotated so that the cup type grinding stone grinds the side surface of the grinding object while the grinding object is axially rotated and moved in the axial direction. Thereby, the outer peripheral surface of the grinding object is finish-ground by the bottom grinding stone portion of the cup type grinding stone while the grinding object is rough-ground by the side grinding stone portion to obtain a ground product.