Numerical controller, CNC machine tool, numerical control method and non-transitory computer readable medium recording a numerical control program

A numerical control method of a numerical controller, the numerical control method comprising:

• detecting a feature of a machined shape from a machining program that commands a movement of a tool or a workpiece;
• calculating, based on a servo parameter of a servo controller that drives the tool or the workpiece, the feature of the machined shape detected from the machining program and a machining requirement that specifies a machining condition, a relation formula that determines an inward-turning amount of a machining path with respect to a program path;
• and
• determining a feedrate that is optimized with the relation formula,
• wherein the inward-turning amount of the machining path is a shape error indicating a difference between the machining path and the program path, the shape error being a sum of a first error caused by a delay in a servo system and a second error caused by acceleration/deceleration after interpolation, and
• wherein the relation formula that determines the inward-turning amount of the machining path is composed of a first relation formula that determines the first error caused by a delay in a servo system and a second relation formula that determines the second error caused by acceleration/deceleration after interpolation.

A non-transitory computer readable recording medium recording a numerical control program which instructs a computer serving as a numerical controller to execute:

• processing which detects a feature of a machined shape from a machining program that commands a movement of a tool or a workpiece;
• processing which calculates, based on a servo parameter of a servo controller that drives the tool or the workpiece, the feature of the machined shape detected from the machining program and a machining requirement that specifies a machining condition, a relation formula that determines an inward-turning amount of a machining path with respect to a program path;
• and
• processing which determines a feedrate that is optimized with the relation formula,
• wherein the inward-turning amount of the machining path is a shape error indicating a difference between the machining path and the program path, the shape error being a sum of a first error caused by a delay in a servo system and a second error caused by acceleration/deceleration after interpolation, and
• wherein the relation formula that determines the inward-turning amount of the machining path is composed of a first relation formula that determines the first error caused by a delay in a servo system and a second relation formula that determines the second error caused by acceleration/deceleration after interpolation.