Numerical control device, method of controlling the same, and system program therefor

A method of controlling a numerical control device, by controlling a machine tool having a plurality of linear movement axes and at least one axis of rotational movement axes for turning a table, for machining using a tool a workpiece fixed to the table, the method comprising:

• an interpolation-command reading step of reading an interpolation command included in a machining program;
• an interpolation-command determination step of determining whether the interpolation command read in the interpolation-command reading step is an interpolation command in a non-machine coordinate system with respect to a non-machining operation;
• a first driving step of driving, when the interpolation command is determined, in the interpolation-command determination step, not to be an interpolation command in the non-machine coordinate system with respect to the non-machining operation, a servo motor corresponding to each of the movement axes in accordance with the interpolation command;
• and
• a second driving step of driving, when the interpolation command is determined, in the interpolation-command determination step, to be the interpolation command in the non-machine coordinate system with respect to the non-machining operation, a servo motor corresponding to each of the movement axes, so that, after the interpolation command is transformed to an interpolation command in a machine coordinate system, the tool moves by interpolation from a start-point coordinate to an end-point coordinate in the interpolation command along a linear path.

A system program to be executed by a central processing unit of a numerical control device, by controlling based on a machining program a machine tool having a plurality of linear movement axes and at least one axis of rotational movement axes for turning a table, for machining using a tool a workpiece fixed to the table, the system program comprising:

• an interpolation-command reading step of reading an interpolation command included in a machining program;
• a coordinate-system transformation command determination step of determining whether a coordinate-system transformation command for transforming the interpolation command from an interpolation command in a non-machine coordinate system into an interpolation command in a machine coordinate system is attached to the interpolation command read in the interpolation-command reading step;
• a first interpolation step of obtaining, when the coordinate-system transformation command determination step determines that the coordinate-system transformation command is not attached to the read-in interpolation command, a first movement amount corresponding to each of the movement axes in accordance with the interpolation command;
• a second interpolation step of transforming, when the coordinate-system transformation command determination step determines that the coordinate-system transformation command is attached to the read-in interpolation command, the read-in interpolation command into an interpolation command in the machine coordinate system, to obtain a second movement amount corresponding to each of the movement axes in accordance with the transformed interpolation command;
• and
• a driving step of driving a servo motor corresponding to each of the movement axes based on the first movement amount or the second movement amount.