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.

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 grinding apparatus includes a table that holds a workpiece, and a grinding unit including a grinding wheel mounted to a spindle. The grinding wheel has a grindstone formed by binding abrasive grains with a bonding agent. In addition, the grinding apparatus further includes: a grinding water supply unit that supplies grinding water to at least the grindstone; a light applying unit that is disposed adjacent to the table and that applies light to a grinding surface of the grindstone grinding the workpiece held by the table; and a light applying unit moving section by which the light applying unit can be positioned at a first position on a rotational trajectory of the grinding wheel in the case where the grinding wheel has a first diameter and a second position on a rotational trajectory of the grinding wheel in the case where the grinding wheel has a second diameter.

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.

An apparatus comprising a workpiece spindle for accommodating a gear wheel workpiece, wherein the gear wheel workpiece is rotationally drivable about a workpiece axis of rotation, a first tool spindle for accommodating a first tool, wherein the first tool is rotationally drivable about a first tool axis of rotation, and comprising multiple NC-controllable axes, which are designed to move the first tool in relation to the gear wheel workpiece so that tooth flanks of the gear wheel workpiece can be machined using the first tool, a second tool spindle for accommodating a second tool, wherein the second tool is rotationally drivable about a second tool axis of rotation, a linear carriage, which supports the second tool spindle and comprises an NC-controllable linear drive to be able to linearly displace the linear carriage along a linear guide in relation to the gear wheel workpiece.

A grinding stroke control device for a valve stem grinding apparatus is fixed to a processing machine and provided for gripping a valve stem or a test bar. Using the hand wheel, the dial gauge and the positioning seat can obtain an initial position, then moving the measuring meter of the positioning mechanism along the transverse direction to make sure the valve stem has the right length with a standard valve clearance. By such arrangements, the grinding stroke control device for a stem valve grinding apparatus of the invention can have a less complicated structure and therefore is more convenient to operate.

Provided are a roll polishing rotary grinding stone and a roll polishing device and method which are configured to stably perform roll polishing without making the surface roughness of a surface to be processed non-uniform by preventing polishing debris to be generated during polishing from being accumulated in a recess at a center of a polishing surface of the roll polishing rotary grinding stone body. The roll polishing rotary grinding stone includes: a rotary grinding stone body having a rotary shaft mounted on a back end face and a polishing surface formed on a front end face; and a recess formed at a center of the front end face of the rotary grinding stone body, the roll polishing rotary grinding stone being configured to perform vertical polishing with respect to a surface of a roll by bringing the polishing surface into contact with the surface of the roll, in which the recess is formed into a tapered recess in which an inner peripheral surface of the recess is increased in diameter from the back end face of the rotary grinding stone body toward the front end face of the rotary grinding stone body.

A grinding machine includes a manual rotating handle provided with a rotation detector that outputs a rotation detection signal so that the position of a grinding wheel with respect to a workpiece can be relatively moved in accordance with the rotation detection signal. The grinding machine further includes a grinding wheel, a moving apparatus that moves the position of the grinding wheel with respect to a workpiece W, a proximity detector that outputs a proximity detection signal corresponding to a relative position or a relative distance between the workpiece and the grinding wheel, a manual rotating handle provided with a rotation detector, and a control apparatus that controls the moving apparatus based on the rotation detection signal. The manual rotating handle is provided with a rotational-torque varying apparatus. The control apparatus controls the rotational-torque varying apparatus based on the proximity detection signal.

A grinding stroke control device for a valve stem grinding apparatus is fixed to a processing machine and provided for gripping a valve stem or a test bar. Using the hand wheel, the dial gauge and the positioning seat can obtain an initial position, then moving the measuring meter of the positioning mechanism along the transverse direction to make sure the valve stem has the right length with a standard valve clearance. By such arrangements, the grinding stroke control device for a stem valve grinding apparatus of the invention can have a less complicated structure and therefore is more convenient to operate.

A grinding apparatus includes a table that holds a workpiece, and a grinding unit including a grinding wheel mounted to a spindle. The grinding wheel has a grindstone formed by binding abrasive grains with a bonding agent. In addition, the grinding apparatus further includes: a grinding water supply unit that supplies grinding water to at least the grindstone; a light applying unit that is disposed adjacent to the table and that applies light to a grinding surface of the grindstone grinding the workpiece held by the table; and a light applying unit moving section by which the light applying unit can be positioned at a first position on a rotational trajectory of the grinding wheel in the case where the grinding wheel has a first diameter and a second position on a rotational trajectory of the grinding wheel in the case where the grinding wheel has a second diameter.