| 摘要 |
In an initial stage the lens edge(R) is milled to a specific contour and in a final finishing stage the edge profile is completed and chamfers provided. Both initial milling and final finishing of the lens edge are effected with a combination tool(10) having milling cutters(26,28) and one or more rotating machining cutters(36). During the milling stage the tool is rotated around its axis(C) at a speed(nC) and prior to and during the machining stage makes a controlled angular rotation(psiC). Prior to initial milling and/or between this operation and the final finishing the lens radii and height values are measured and the latter are used in both milling and final finishing stages. In the finishing operation the combination tool(10), is rotated around its axis and moved radially relative to the lens rotation axis(B) so that the machining cutter(36) contacts the lens edge and the cutting face makes an angle with a tangent at the contact point. During machining of a non-circular lens the combination tool is rotated through an angle psiC = f (psiB, rB(approximatelyuB)) dependent on the lens rotation angle(psiB) and the lens radius(rB(approximatelyuB)) so that the angle between the tool cutting face and a tangent at the contact point remains constant. During final finishing an angled ridge with two flanks may be machined around the lens edge(R) by either: a) bevelled edges(32,34) at each end of the milling cutters(26,28); b) bevelled edges at each end of the machining cutter which cut each flank in turn; c) a V-shaped cut-out in the machining cutter. Alternatively a groove(N) may be cut around the lens edge by a cutting edge on the machining cutter. Chamfers may be produced between the lens edge and the optical faces(O1,O2) during final finishing using the bevelled edges at each end of the machining cutter. Edge polishing is effected by the machining cutter with a negative cutting angle. Independent claims are included for: a) the combination tool(10) which comprises a body(20) carrying milling cutters(26,28) and at least one axially displaced machining cutter(36) or alternatively milling cutters with a machining cutter at the same axial point between each milling cutter and offset radially inside the milling cutter cutting circle; b) lens edge machining equipment which includes lens holders(14,16) and a combination tool rotation spindle(12) with two linear movement directions(X,Z) and a controlled rotation through a specific angle(psiC) to enable a machining cutter to contact the lens edge at a desired point. |
