Method and device for forming a bevel on the edge of a glass lens

A spectacle-lens edge-machining machine, having

• at least one spectacle-lens edge-machining tool (3) with a bevel groove (11),
• a rotable spectacle-lens holding shaft (5, 6) which is at least radially adjustable relative to the spectacle-lens edge-machining tool (3),
• a control device (12) controlling the spectacle-lens edge-machining machine,
• an apparatus (10) which is connected to the control device (12) and is intended for scanning the spectacle-lens edge-machining tool (3) with regard to its diameter and the cross-sectional shape of its bevel groove,
• an apparatus (39) which is connected to the control device (12) and is intended for scanning the bevel groove (35) of a spectacle-lens opening (34) in a selected spectacle frame (42), including the cross-sectional shape,
• a comparison device in the control device (12) for comparing the values of the cross-sectional shape of the bevel groove (35) of the spectacle frame (42) with the values of the cross-sectional shape of the bevel groove (11) of the spectacle-lens edge-machining tool (3), and
• devices for controlling the carrying out of the machining of the bevel using the determined values wherein, if the compared values lie within a predeterminable first tolerance range, or the devices carry out the machining of the bevel using a correction value, and if the compared values satisfy at least one of lying within a second tolerance range and the diameter of the spectacle-lens edge-machining tool is smaller than a predeterminable minimum value, or the devices not carrying out the machining of the bevel, if the compared values lie outside both tolerance ranges.