A spindle apparatus for supporting and rotating a workpiece in a grinder. The spindle apparatus includes a workpiece spindle rotatably supported on a spindle head and driven for rotation by a motor, and a spindle plate mounted to the front end of the workpiece spindle and including an eccentric drive pin. The workpiece spindle has a bore in which a ram is axially movable. A center is fit in the front end of the ram. A unit is provided to advance the ram to engage with one end of the workpiece when the workpiece is to be supported. A rotary sleeve is rotatably supported on the front end of the ram and includes an engagement portion which is displaceable in the axial direction of the spindle and engageable with the drive pin in the direction of rotation. A driving unit is mounted to the front of the rotary sleeve to engage the workpiece in the direction of rotation when the ram is in its advanced position to thereby transmit rotation.

Equipment for the grinding of material samples includes a console and a frame structure. A turntable is mounted on the console and frame structure, with the turntable having a material sample holding portion capable of releasably holding a plurality of material samples thereon. At least one vertically movable grinding spindle is arranged above the turntable. A mechanism is further provided for laterally oscillating the turntable relative to the console and frame structure as well as relative to the at least one vertically movable grinding spindle. A programmable control unit is connected with the turntable, movable grinding spindle and mechanism for laterally oscillating the turntable for controlling grinding.

A numerical controller for a cam grinding machine, which has a cam drive unit and a grinding wheel drive unit, includes a memory for storing profile data of a cam corresponding to angular positions thereof. A data processor is provided for reading out the profile data from the memory so as to generate a rotational speed command indicating a rotational speed of the cam and a feed rate command indicating a feed rate of the grinding wheel at every unit angle rotation of the cam, wherein the rotational speed command and the feed rate command are so decided as to reduce the rotational speed of the cam and the feed rate of the grinding wheel while the side portions of the cam are ground. A pulse distribution circuit is connected to the data processor and responsive to the rotational speed command and the feed rate command therefrom for distributing pulses to the cam drive unit and the grinding wheel drive unit.

A grinding method for a vertical type of double disk surface grinding machine comprising a pair of rotating grinding wheels vertically opposed to each other and vertically movable and a moving table for moving a work having a work holding jig, wherein vertical positions of the upper and the lower surfaces of the work to be ground prior to the grinding operation are measured by means of a pre-grinding dimension measuring instrument disposed in a vicinity of the work attaching/detaching position and the standby positions of the grinding wheels are set based on the measured values in a step, the work is moved to the grinding position and the grinding wheels are moved at a high feeding speed from the set standby positions to grinding start positions in contact with the work or positions immediately before making the contact in a subsequent step, and the work is ground at a grinding speed lower than the feeding speed in a further subsequent step.