Method and tool head for machining optically active surfaces, particularly surfaces of progressive spectacle lenses, which are symmetrical in pairs

Abstract

A method and a tool head are provided for the chip-removingly machining of pairwise symmetrical, optically effective surfaces, in particular of surfaces of progressive power spectacle lenses. The spectacle lenses are rotated about a first axis and are displaced along the axis. Further, a chip-removing tool is provided being positioned and being adapted to be fed-in, such that a cutting edge of the tool is guided over the surface along a spiralled path and along an elevation function given by the shape of the spectacle lens, when the latter is rotated about the first axis. For machining right side spectacle lenses and left side spectacle lenses, the right side spectacle lenses are rotated about the first axis in a first rotational direction, and the left side spectacle lenses are rotated about the first axis in a second rotational direction opposite the first rotational direction. The tool head comprises a chucking structure defining an axis of the tool head, and a tool carrier section having at least two lathing tools arranged at a periphery thereof. The one lathing tool of the pair is oriented in the one circumferential direction of the periphery, and the other lathing tool of the pair is oriented in the opposite circumferential direction of the periphery. At least one, preferably all of the lathing tools are provided with an adjustment device allowing an adjustment of a point of engagement of the lathing cutting edge.