| 摘要 |
PURPOSE:To enable a ball unit of high sphericity to be stably further efficiently manufactured over a long time with no replacement of a driving lap by forming it into a cylindrical shape and specifying its thickness. CONSTITUTION:While holding a spherical workpiece 3 in magnetic fluid 7, containing an abrasive grain, by a float 5 receiving floating force by the magnetic field formed in the magnetic fluid by a magnet 6, driving lap 1 and the internal peripheral surface of a guide ring 4, this driving lap 1 is rotated, polishing the spherical workpiece 3. Here the driving lap 1 forms a cylindrical shape, setting its thickness B larger than 0.2D and smaller than (D-A). Here the alphabet D shows a diameter of the spherical workpiece 3, while the alphabet A shows a distance between the internal peripheral surface of the guide ring 4 and the external wall surface of the driving lap 1. Thus by setting the thickness B, a ball unit of high sphericity can be stably further efficiently manufactured over a long time with no replacement of the driving lap 1. |
