Method for constructioning tool approach and retraction paths from preset patterns

A three-dimensional tool path determination method, for an apparatus having a memory, for determining at least one tool path out of an approach tool path along which a tool of a machine tool having three or more controlled axes is made to approach a workpiece, and a retraction tool path along which the tool is retracted from the workpiece after machining is completed, said method having the steps of:

• (a) entering data into the memory defining a plurality of tool path patterns, each having a target position;
• (b) designating one of said tool path patterns, said designated tool path pattern having a variable portion;
• (c) entering data into the memory specifying said variable portion of said designated tool path pattern;
• (d) monitoring a current position of the tool;
• (e) comparing the current position with the target position contained in said data specifying said variable portion;
• (f) determining an approach path using the designated tool path pattern and the data specifying said variable portion in a case where the current position is located above the target position;
• and
• (g) determining a retraction tool path using the designated tool path pattern and the data specifying said variable portion in a case where the current position is located below the target position.