Area cutting method

An area cutting method comprising the steps of:

• creating positioning data for moving a tool and cutting in a predetermined first direction along a cutting path PT.sub.i to machine the interior of an area, the first direction being limited to a substantially two-dimensional plane;
• moving the tool and cutting in the first direction along the next cutting path PT.sub.i+1, which is shifted by a predetermined amount within the two-dimensional plane, to machine the interior of the area;
• creating positioning data for moving the tool and cutting in a cutting-feed mode along the curve of the external shape within the two-dimensional plane from a machining end point Q.sub.i on an i-th cutting path PT.sub.i to a machining end point Q.sub.i-1 on an (i-1)th cutting path PT.sub.i-1 after cutting path PT.sub.i ;
• creating positioning data for moving the tool in a rapid-traverse mode from the point Q.sub.i-1 to a machining starting point P.sub.i on the cutting path PT.sub.i after cutting path PT.sub.i
• creating positioning data for moving the tool in the cutting-feed mode along the curve of the external shape within the two-dimensional plane from the machining starting point P.sub.i on the cutting path PT.sub.i to a machining starting point P.sub.i+1 on the next cutting path PT.sub.i+1 before cutting path PT.sub.i+1 ;
• and
• repeating the creating steps to create all positioning data for area cutting within the two-dimensional plane, and performing area cutting by using said positioning data.

A substantially two-dimensional area cutting method using a cutting tool having a cutting speed, comprising the steps of:

• (a) cutting from point P.sub.i to point Q.sub.i where P.sub.i is a start point of a current path and Q.sub.i is an end point of a current path;
• (b) cutting from point Q.sub.i to point Q.sub.i-1 where Q.sub.i-1 is an end point of a previously cut path;
• (c) moving the tool at speed greater than the cutting speed from point Q.sub.i-1 to point P.sub.1 ;
• and
• (d) cutting from point P.sub.i to point P.sub.i+1 where P.sub.i+1 is a start point of a succeeding path, points P.sub.i, P.sub.i+i, Q.sub.i and Q.sub.i-i lying in a substantially two-dimensional plane.