Numerical Simulation Of Complex Spiral Surface Envelope Milling

In the envelope milling of complex helical surface, the algorithm about tool path and the precision of the programming are important factors about its machining accuracy. In order to improve the machining accuracy of complex helical surface, this paper studied the algorithm about its tool path, put forward a algorithm of tool path based on the minimal directed distance. To ensure the accuracy of the NC (numerical control) programming, this paper have to interpolation simulate with Archimedes spiral interpolation for NC interpolation nodes according to the error control values strictly, setting up the NC code finally.The simulation of tool-path is the core of this paper, and the numerical algorithm of tool-path is a innovation of this paper. Building three-dimensional numerical geometric model of tool and workpiece surface, and setting up a numerical calculation model consistent with the real operation through the coordinate-transformation matrix, to ensure the accuracy and efficiency, simplifying the minimal directed distance between tool and workpiece into a two-dimensional problem by spatial discretization thought, setting up the simulation algorithm of tool-path finally. This paper obtains NC code parameter information with interpolation simulating for NC interpolation nodes according to the theory of Archimedean spiral interpolation curve. A optimization method of tool feed rate by cutting the same volume for helical surface processing is used in this paper, which keep the stabilized cutting performance of the tool, and ensure the workpiece processing quality and efficiency. Design NC code programming system for screw machining based on the principle of simple and easy to operate, which calculate tool-path through computer numerical simulation,thus, it’s flexible and without restraint of the complexity level of helical surface, so it can calculate tool-path accurately and effectively.To shorten the development cycle of screw products, decrease the costs and ensure the correctness of processing procedure. The screw envelope milling NC machine model and virtual machining model are established based on the VERICUT virtual machining software platform. A virtual simulation machining of the screw is conducted in the VERICUT environment. The quality analysis and judgment of the machining result are carried out, verifying the correctness of the NC code.This paper also study on the effect of processing parameters,which contains tool installation angle, nose angle and corner radius on error by the NC code programming system, an optimization method is further proposed to improve the quality of screw machining. Realizing the calculate of high precision tool-path for complex helical surface processing by numerical simulation method, NC code generated by the method with high precision, besides,the method is flexible and widely applicable, it can calculate tool-path for the envelope milling of multiple helical surface.