CNC data correction method

A CNC data correction system comprising:

• a CNC machine tool;
• and
• a computer with a CAD/CAM function connected to said CNC machine tool by a communication circuit,
• said CNC machine tool including:
• sampling means for sampling running machining information for each predetermined cycle in accordance with NC data;
• and
• data transfer means for transferring the machining information obtained by said sampling means to said computer through said communication circuit in response to a command,
• said computer including:
• storage means for correspondingly storing a command position in the NC data corresponding to each point in CAD data corresponding to the starting or ending point of each block of the NC data and the machining information corresponding to the point;
• correction value calculating means for calculating a correction value for the NC data for each point based on the command position for each point stored in said storage means and the machining information;
• normal calculating means for calculating a normal at the point in said CAD data;
• correction data originating means for determining a modified command position for the starting or ending point of each block of the NC data by using the normal and the correction value which are obtained for each point in said CAD data corresponding to the starting or ending point of each block of the NC data by using said normal calculating means and said correction value calculating means;
• and
• modified data transfer means for transferring the NC data modified by said correction data creating means to the CNC machine tool side through said communication circuit in response to a command.

A CNC data modification method, comprising;

• obtaining actual machining position data corresponding to a command position for a tool;
• obtaining the difference between an actual machining position and the command position;
• obtaining a data correction value based on the difference;
• calculating a normal corresponding to the data correction value;
• and
• modifying the command position data of next machining by using the normal and the data correction value.