Polishing disc for a tool for fine processing of optically effective surfaces on spectacle lenses

A tool for fine processing of optically effective curved surfaces at spectacle lenses, comprising a tool mounting head securable to a spindle shaft of a tool spindle to be capable of axial and rotational entrainment, characterized in that a polishing disc for a tool for fine processing of optically effective curved surfaces on spectacle lenses is exchangeably mounted on the tool mounting head, said polishing disc comprising a base body which has a center axis and a substantially symmetrical semi-spherical end surface about said center axis and to which is secured an intermediate layer of a resilient material, on which a polishing medium carrier rests, the intermediate layer being softer by comparison with the base body, wherein the intermediate layer has at least two regions of different hardness, which are arranged in succession in the direction of the center axis and which are formed by mutually different foam material layers, wherein the foam material layer adjoining the base body is softer than foam material layer on which the polishing medium carrier rests, each layer having a substantially symmetrical semi-spherical end surfact about said center axis, wherein, as determined for the case of whole-area compression, the static modulus of elasticity of the harder foam material layer is between 0.40 and 1.50 N/mm2, whereas the static modulus of elasticity of the softer foam material layer is between 0.25 and 0.45 N/mm2, and wherein for mounting purposes the base body of the polishing disc and the tool mounting head are provided with complementary structures for axial detenting and rotational entrainment of the polishing disc with and by the tool mounting head.