Numerical control method and device thereof

A numerical control method of controlling a multiaxis machine tool which has a rotary shaft for rotating or tilting a rotary table on which a workpiece is provided and is configured to control the posture of a tool relative to the workpiece, the numerical control method comprising:

• a step of calculating an interference avoidance height of the tool at which the tool, which moves in a Z axis direction so as to move close to and away from the rotary table, does not interfere with the rotary table and the workpiece over an entire movable range of the rotary shaft to which a movement command is input, the step being triggered by starting of the movement command of the rotary shaft and being performed when the rotary shaft is stopped;
• a step of determining whether the tool interferes with the rotary table or the workpiece by comparing a current Z axis height of a tip of the tool with the interference avoidance height obtained in the previous step;
• a step of performing warning without moving the rotary shaft to which the movement command is input and waiting for input of a command for starting an avoiding operation to the interference avoidance height, in a case where it is determined in the previous step that interference occurs;
• and
• a step of generating a command for movement in the Z axis shaft direction to the interference avoidance height when the command for starting the avoiding operation is output.

A numerical control device for controlling a multiaxis machine tool which has a rotary shaft for rotating or tilting a rotary table on which a workpiece is provided and is configured to control the posture of a tool relative to the workpiece, the numerical control device comprising:

• an avoidance-height calculating unit that calculates an interference avoidance height of the tool at which the tool, which moves in a Z axis direction so as to move close to and away from the rotary table, does not interfere with the rotary table and the workpiece over an entire movable range of a rotary shaft to which a movement command is input, the calculation being triggered by start of the movement command of the rotary shaft and being performed when the rotary shaft is stopped;
• an interference determining unit that determines whether the tool will interfere with the rotary table or the workpiece by comparing a current Z axis height of a tip of the tool with the interference avoidance height obtained by the avoidance-height calculating unit;
• a warning unit that performs warning without moving the rotary shaft to which the movement command is input and waiting for input of a command for starting an avoiding operation to the interference avoidance height, in a case where the interference determining unit determines that interference will occur;
• and
• an avoiding-operation generating unit that generates a command for movement in the Z axis direction to the interference avoidance height when the command for starting the avoiding operation is output.