POLISHING MACHINE

1334822 Polishing SCHUMAG SCHUMACHER METALLWERKE GmbH 11 Feb 1972 [19 Feb 1971] 6588/72 Heading B3X A machine for polishing an elongate cylindrical workpiece 4 comprises at least one pair of rotating discs 11, 12, the faces of which eccentrically face each other so that their peripheries overlap to provide a working zone 7 through which the workpiece is fed, the direction of rotation being such that opposing points of the surfaces in the zone along a line between the axes of the discs have opposite directions of motion, the zone comprising a neutral zone wherein the directions of motion of opposing points are equal and opposite, and a polishing zone on each side of neutral zone wherein the directions of motion of opposed points are opposite and unequal, at least one of the discs at a radial distance corresponding to the neutral zone having an annular groove 9. The discs are of polished steel and have slightly conical surfaces and rotate in the direction of arrows 15, 16. At the neutral zone each disc has a V-shaped groove 9, 10 where the workpiece would have only rolling contact with the discs, the zones at each side of the neutral zone providing rubbing contact with the discs. It is stated that elimination of the rolling contact prevents the creation of shadow effects and roughness. The edges of the grooves may have transition zones (18, 19, Fig. 3, not shown) at a lesser angle than the sides of the groove.