Control of CNC machine tools

A method of operating of multi-axis CNC machine having workpiece mounting means for mounting a workpiece:

• a cutting tool operable upon said workpiece, a plurality of machine members and a plurality of controllable joint means movable under the control of the machine to cause relative movement between the cubing tool and the workpiece mounting means, wherein said plurality of joint means include a plurality of linear joints and at least one rotary joint, said method comprising the steps of:
• programming the machine with a plurality of programmable linear axes and at least one programmable rotary axis;
• programming the machine to control movement of said plurality of joint means relative to said programmable axes so as to cause the cutting tool to move along a programmed pall, said programmable linear and rotary axes including principal programmable axes constituting the minimum number of axes required to position the cutting tool relative to the workpiece mounting means and at least one additional concurrently programmable axis;
• and programming the machine to control movement of at least one of said joint means relative to said additional concurrently programmable axis without physical location of said additional concurrently programmable axis by said joint means.

A multi-axis computer numerically controlled (CNC) machine tool comprising:

• workpiece mounting means for mounting a workpiece thereon;
• a cutting tool movable relative to the workpiece mounting means;
• a plurality of machine members;
• and
• a plurality of controllable joint means movable to cause the relative movement between said cutting tool and said workpiece mounting means;
• and
• programmable control means programmed to control automatically the position and orientation of said plurality of joint means in accordance with a part program;
• the machine tool having a plurality of principal programmable positioning directions or axes which constitute tho minimum number of programmable axes required to position and orientate the cutting tool relative to the workpiece mounting means;
• wherein the machine tool has at least one synthesized additional concurrently programmable axis, and the programmable control means is programmed to control movement of said cutting tool or said workpiece mounting means in relation to said at least one additional concurrently programmable axis in accordance with said pan program without physical location of said at least one synthesized additional programmable axis by said joint means.