Method for determining location of a sheet edge

摘要

The method is intended for determining the location of the edge (1a) of a sheet (1) having an uneven surface and placed on the work table of a coordinate machine comprising a carriage (2) with a working instrument (3) mounted on it, and a regulator for adjusting the distance between the working instrument (3) and the surface of the sheet (1), with a pick-up (4) mounted on the carriage (2) to detect this distance. In the course of implementation of the method, the carriage (2) is moved along the surface of the sheet (1) in the direction of its edge (1a) after switching on the regulator. After the pick-up (4) signal exceeds a predetermined limit, the direction of movement of the carriage (2) is reversed and it is moved by a small predetermined distance, after which the regulator is switched off and the carriage (2) is again moved in the direction of the same edge (1a) of the sheet (1). The location of the edge (1a) of the sheet (1) is determined from the coordinates of the carriage (2) at the time when the signal of the pick-up (4) again exceeds the predetermined limit.