Patent ID: 7050883

Claim:
An off-line feed rate scheduling method of a CNC machining process that is performed according to workpiece geometry and a given set of NC code provided from a CAD/CAM system, the method comprising: selecting a constraint variable and inputting a reference value related to the constraint variable; estimating a cutting configuration where a maximum constraint variable value (CW) occurs through ME Z-map modeling; obtaining the estimated cutting configuration and estimating a specific rotation angle (φ s ) where the maximum constraint variable value occurs through constraint variable modeling; calculating a feed rate that satisfies the reference value related to the constraint variable at the estimated specific rotation angle; and applying the calculated feed rate to the NC code, wherein the calculating a feed rate comprises: inputting specific feed rates f 1 and f 2 (f 1 <f 2 ); calculating maximum constraint variable values CVV 1 and CVV 2 corresponding to the feed rates f 1 and f 2 , respectively, at the specific rotation angle; approximating a feed rate f next that corresponds to a reference value RV of a constraint variable value using the formula, f next = f 1 + ( RV - CVV 1 ) ⁢ ( f 2 - f 1 ) CVV 2 - CVV 1 ; calculating a constraint variable CVV next in the case where the feed rate is f next ; and determining using the formula below if the constraint variable value CVV next when compared to the reference value RV is less than an error limit, applying the feed rate f next to the NC code when it is less than the error limit, replacing the feed rate f 2 by f next and repeating the process of obtaining f next when this value is not less than the error limit and the reference value RV is greater than the constraint variable value CVV next , and replacing the feed rate f 1 by f next and repeating the process of obtaining f next when this value is not less than the error limit and the reference value is not greater than the constraint variable value CVV next , where CVV next - RV RV < Error ⁢ ⁢ Limit ⁢ .