| Summary: | 碩士 === 國立中央大學 === 機械工程研究所 === 90 === CNC machine tools have typically used linear and circular segments to generate tool paths. These segments are inputted to the controller by command data known as G-code. More recently, part geometry has become more complex requiring the use of more advanced curve geometries. Parametric curves are becoming more popular in design systems and these curves are approximated by a large number of linear segments before sending them to the controller. Unfortunately, to achieve the desired tolerance, a large number of very small line segments are produced. These can be prohibitive given memory capabilities of the CNC machine tools. In addition, the shortness of the linear segments can cause machine to halt because jerk of the machine tool is too large. To solve the problems, several NURBS interpolation methods have been developed. These methods can reduce the amount of data required by controllers and allow tools to move more smoothly. So it is easily to realize machining at high speed and high precise.
The purpose of this paper is to present several methods to implement NURBS interpolation. To begin with, this paper proposes two methods which fit line tool paths with interpolation and approximation. The purpose generates smooth parametric contour paths for solving the unsmooth problem resulted from massive short lines. Finally, this paper uses a PC-based controller as a real application for verifying machining results.
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