Numerical controller and control method

A numerical controller that controls a machine tool capable of freely changing a relative direction of a cutting tool with respect to a workpiece and performs turning on the workpiece, the numerical controller comprising:

• a memory configured to store a program;
• and
• a processor configured to execute the program and control the numerical controller to:
• decode a command of a machining program;
• and
• generate and store geometrical information related to the tool,
• wherein the processor
• decodes a depth amount of cut during roughing from a command of the machining program,
• generates a finished shape of the workpiece from the command,
• generates a path for roughing based on the decoded depth amount of cut during the roughing and the generated finished shape of the workpiece,
• provisionally determines a direction of the tool, based on the geometrical information related to the tool, and a depth of cut and a round-up path generated,
• determines whether to omit a round-up operation, based on the direction of the tool provisionally determined, the depth of cut, and the round-up path,
• omits, when the round-up operation is determined to be omitted, the round-up operation and generate a new path that directly moves to an end point of an operation next to the omitted round-up operation, and
• determines the direction of the tool for each machining geometry change point, at which the finished shape of the workpiece changes, in the path for roughing including the generated new path,
• wherein the machine tool is controlled by the numerical controller based on the path for roughing in which the round-up operation is omitted so as to be shortened.