Numerical control unit

A numerical control unit using fuzzy logic to control the cutting of a workpiece with a tool comprising:

• a knowledge storage section having a plurality of rules in an IF . . . THEN format for changing a cutting condition and comprising a rule description part and membership function part, at least one of said rules being established based on material characteristics of said tool;
• an inferring section for inferring the optimum value of the cutting condition on the basis of a number of said rules, including said at least one rule, stored in said knowledge storage section;
• and
• means for correcting a membership function in said knowledge storage section in accordance with a workpiece shape, said numerical control unit operating to make inference according to the corrected contents of said knowledge storage section.

A numerical control machining unit for machining a workpiece, comprising:

• a knowledge storage section storing a plurality of rules, by which a cutting condition is defined, in a production rule format;
• an inferring section for inferring a desired cutting condition according to the rules stored in said knowledge storage section, said inferring section comprising:
• means for extracting only those rules that are to be judged from among a plurality of said rules stored in the knowledge storage section, said rules being extracted including at least one rule which defines a rate at which movement of the machine tool is changed based on a position of the machine tool with respect to a corner of the workpiece;
• and
• means for changing said cutting condition on the basis of only said extracted rules.

A method of controlling the machining of a workpiece using fuzzy logic comprising the steps of:

• storing a first plurality of rules in a production format, at least one of said rules defining a rate at which movement of the machine tool is changed based on a position of the machine tool with respect to a corner of the workpiece;
• storing input membership functions employed for fuzzy inference;
• and
• performing fuzzy inference on the input membership functions on the basis of a number of said stored rules, including said at least one of said rules, to derive output membership functions and deducing from said output membership functions a conclusion concerning the machining of said workpiece.