Abstract: To solve the problem of early NC programs lack of corner processing, an
algorithm about corner recognition and automatical generation of processing program for planar
profiles around NC code is proposed. This method can meet the product upgrades and high
processing requirements of NC machining, and further ensure the security and the surface quality
of parts. Firstly the common NC code structure is summed up. Secondly the NC Code geometry
representation is expressed as edge chains. Then the direction of those chains and the edge tangent
in chains are computed. And the corners are classed as point and arc corners. At the same time, the
recognition rules of corner, considering these factors such as discrete structure of arc corner and
closure of chains, are presented. To reduce the instantaneous cutting amount of processing at the
corner position from the tool axis, Corner machining is layered. Each layer of corner processing
tool path consists of feeding, cutting in, corner processing, cutting out and retracting sections.
Layers of path are connected with feeding-retracting lines. Finally, an experimental result is
showed to prove this algorithm.

Key words: numerical control processing, corner processing, NC code, post-processing