KINEMATIC PROPERTIES OF TRAJECTORIES DESCRIBED BY NURBS

И. В. Бычков, А. К. Мялица, Н. И. Бычков, А. М. Григорович

Abstract


The purpose of the article is to solve a number of problems of using NURBS curves in the implementation of high-speed processing of complex products on machining equipment. NURBS-splines are becoming increasingly popular among CNC specialists, which is motivated by their wide application in the modeling of the production facility in CAD/CAM systems. Advanced manufacturers of CNC devices in the number of shaping algorithms necessarily include NURBS - interpolation. But despite the extensive capabilities of CAD/CAM systems for describing the shape of products and toolpaths of processing equipment using spline curves, many manufacturers of CNC systems use more primitive methods for describing the trajectory of the tool - piecewise linear and linear-circular. This negates the benefits of using spline curves, including smooth curvature change, which is very important when moving the tool at high speed processing. Such simplification of trajectories is associated with a number of difficulties in the implementation of spline curves in modern CNC systems. In addition, the requirements for industrial cleanliness of the surfaces of the parts is information about the processing parameters, the directions of relative movements of the tool and the workpiece on the finishing operations in order to provide technological conditions to the size of the burrs formed. It is possible that the choice of strategy of processing for obtaining the minimum size of a Burr or reduction of their number. The sizes of the turned-out agnails define methods of their elimination in technological process of production of a detail. Therefore, the provision of technological information using the analytical standard of the part is a necessary condition for ensuring the quality of products and their high reliability. NURBS - interpolation allows to obtain a compact description of the tool movement in the process of forming, which allows to correctly formulate the problem of working of complex-shaped parts.


Keywords


NURBS, interpolation, spline curves, toolpath, CAD/CAM, high speed machining, CNC

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DOI: https://doi.org/10.32620/oikit.2019.85.04

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