| 摘要 |
PURPOSE:To accurately lap a cylinder bore without unevenness, by holding plural grinding wheels, which are movable in the radial direction of a column-shaped tool main unit in a rotary main spindle being permitted to move to a position protruding from an outer surface of this main unit, to the column-shaped tool main unit in a position providing an equal space in the peripheral direction of the plural grinding wheels. CONSTITUTION:A rotary main spindle 9 of a lapping tool 8 is advanced while being rotated, and a cover 12 is adapted to a cylinder block CB of an internal combustion engine. After this cover is adapted to the cylinder block, in no relation to the advancing motion of the rotary main spindle 9 and a tool main unit 10, the cover 12, while it contracts a coil spring 14, relatively moves rearward in the axial direction. As the result, each grinding wheel 11 is successively exposed in accordance with the relative movement of the cover 12 toward the rear, and the grinding wheel 11 is energized outwardly in a radial direction by acting centrifugal force coming into contact with the internal surface of a cylinder bore 1 and generating lapping action. The lapping action by this grinding wheel 11 forms a plateau honing-like surface, having a relatively rough root part between many plateau parts, in the internal surface of the cylinder bore 1. |
