Cylindrical grinding apparatus and method for grinding

A cylindrical grinding apparatus having at least a table on which a cylindrical ingot is placed in a longitudinal direction, a pair of clamps for holding both end faces of the ingot in a vertical direction, a rotation means for driving to rotate the ingot about a central axis and a grinding wheel movable in the direction of a rotating axis of the rotation means, and grinding a side face of the cylindrical ingot,

• the apparatus comprising a centering means composed of at least three rollers and an arm for holding the rollers, the centering means being capable of moving backward and forward against the ingot in a horizontal direction to bring the rollers into pressure contact with the ingot, wherein
• the cylindrical ingot is placed on the table in a longitudinal direction, both end faces of the ingot are held vertically with the pair of clamps after moving the ingot placed in a longitudinal direction onto one of the clamps from the table, the centering means moves backward and forward against the ingot in a horizontal direction to bring the rollers into pressure contact with the side face of the ingot while the ingot is rotated about the central axis with the rotation means so that the rotating axis of the rotation means is aligned with the central axis of the ingot, and thereafter the ingot is ground with the grinding wheel.