Method for generating control command data for controlling a CNC-lathe

A method performed by a computer numerical control (CNC) lathe including computer program code being configured to cause the CNC lathe at least to perform the method for generating control command data, such as NC-code (numerical control code) for controlling the CNC-lathe to perform a turning operation by means of a turning tool, the method comprising the steps of:

• generating the control command data, such as the NC-code (numerical control code), to control the CNC-lathe to perform the turning operation by means of the turning tool;
• selecting an electronic representation of a metal blank;
• selecting an electronic representation of the turning tool;
• selecting a volume of material from the metal blank to be removed by means of the turning tool, said volume being limited by an inner surface and an outer surface, said metal blank being limited by a peripheral surface, wherein the peripheral surface includes the outer surface;
• selecting the inner surface such that the inner surface includes at least one part surface, which is cylindrical, conical or planar;
• selecting an end position;
• selecting a recommended cutting depth for the turning tool;
• selecting a maximum allowed cutting depth for the turning tool;
• and, based on the above selections, generating control command data to:
• (a) command the turning tool to remove a portion of the volume of material through one or more turning passes, which are linear and parallel to a longest part surface of the inner surface, until a cutting depth at a point of the inner surface, which is most remote from the end position is less than or equal to the maximum allowed cutting depth of the turning tool;
• (b) command the turning tool to go into cut at a point of an unmachined inner surface, which is most remote from the end position;
• and
• (c) command the turning tool to move along the inner surface towards the end position until:
• a cutting depth is equal to or greater than one of either the maximum allowed cutting depth or the recommended cutting depth, whereby the turning tool is commanded to move away from the inner surface in a predefined direction, which predefined direction is parallel to the longest part surface of the inner surface, or
• the turning tool reaches a predefined position, whereby the turning tool is commanded to move away from the inner surface, the predefined position is defined as an intersection between the inner surface and a line parallel to and spaced apart by a multiple of the recommended cutting depth of the turning tool from a base line, wherein the base line intersects the longest cylindrical, flat or conical part surface of the inner surface.