Method for measuring three-dimensional curves and thicknesses at the leading and trailing peripheral edges of a shaped and ground spectacle lens

摘要

Process for form-grinding the periphery of a spectacle lens and for scanning the three-dimensional curve and thickness of the form-ground spectacle-lens periphery by means of a computer-controlled spectacle-lens edge-grinding machine, having half-shafts retaining the spectacle lens between them, having a periphery grinding wheel machining the lens periphery, and having a sensor head which measures the spectacle lens in the vicinity of its periphery, in terms of the three-dimensional curve and the lens thickness, and is connected to a computer. In said process, the form-grinding of the spectacle-lens periphery takes place in the central region of the grinding wheel by rotating the half-shafts with the spectacle lens and changing the relative distance of the axes of the half-shafts and the grinding wheel, the rotation of the spectacle lens is stopped when a measurement point is reached, the spectacle lens is displaced, relative to the grinding wheel, axially from the central region to the two edges of the grinding wheel until the front and rear sides of the spectacle-lens periphery make contact with the sensor head, the path or the time from the central region until contact is made with the sensor head is recorded, the measured values are stored in the computer, further rotation of the half-shafts with the spectacle lens takes place, the spectacle-lens edge is form-ground until the next measurement point is reached, the rotation of the spectacle lens is stopped once again, and the measured-value recording and the periphery grinding are continued until at least one complete revolution of the half-shafts with the spectacle lens has ended. By means of this type of measured-value recording, errors in the case of very pronounced conchoidal formation of very thick lenses are avoided. IMAGE