Economical multi-axis numerical control system and inter-linked controlling method thereof

The present invention relates to a numerical control system for machine tool and its control method. In particular it provides a multiple spindle numerical control system formed of microcomputer and one-chip computer control unit and its correspondent coupling control method. Said control unit is correspondent to the working motion shaft being in need of control, and uses the computer to resolve and calculate actual control shaft displacement of every motion shaft on the unit displacement section of working curved surface and dummy reference shaft displacement, then makes linear interpolationoperation for both displacements so as to make programming and operation control. Said invention can be used for working various complex curved workpieces.