Einrichtung zum Polieren von nur geringfuegig von Kugelflaechen abweichenden asphaerischen Linsenflaechen

摘要

947,177. Polishing. RANK PRECISION INDUSTRIES Ltd., [trading as TAYLOR, TAYLOR & HOBSON]. Feb. 15, 1960 [Feb. 19, 1959], No. 5828/59. Heading B3D. In a method of polishing a spherical surface or an aspheric surface of revolution approximating to a basic spherical surface, the element having the surface to be polished and the polishing element are relatively rocked effectively about a pivot axis passing through or at least close to the centre of curvature of the spherical surface to be polished or of the basic spherical surface approximately to the aspheric surface to be polished, the polishing element having a polishing surface which, in all relative positions of the two elements, extends over the whole area of the surface to be polished, and an additional relative movement is applied to the two elements, for varying relatively to the surface to be polished the orientation of the relative rocking movement, by driving one of such two elements rotationally about its axis of symmetry at a speed such that numerous relative rocking movements are completed during one complete relative rotation and thereby slow enough to ensure that such additional relative movement makes negligible contribution to the polishing effect. Polishing apparatus has a fixed base formed of members A1, A2, A3. A member B adjustable along the base member A1 carries a shaft C driven, through reduction gear, by an electric motor D carried by the member B. A polishing device M is mounted on the end of the shaft C. On top of a column A4 carried by the member A2 is a supporting block A5 carrying a vertical pivot shaft E to the lower end of which is secured an arm F. A member G adjustable along the arm F carries a freely rotatable shaft H on the end of which is mounted a workholder N. The upper end of the shaft E has a crank J connected by link J1 to a crank arm J2 on a vertical shaft K driven through belt L1 from an electric motor L. The effective length of the crank arm J2 is adjustable by a pin-and-slot coupling J3. In use, the position of member G on swinging arm 5 is adjusted so that the centre of curvature of the spherical surface to be polished or of the basic spherical surface approximating to the aspherical surface to be polished lies on the axis of the pivot shaft E ; the position of member B on base member A1 is then adjusted to bring the polishing device into engagement with the surface of the workpiece to be polished. The polishing device and workholder may be constructed as in Specification 947,176. Specifications 947,174 and 947,175 also are referred to.