In CAD systems, a surface to be machined is expressed by a series of curves, such as B-spline, Be... more In CAD systems, a surface to be machined is expressed by a series of curves, such as B-spline, Bezier and NURBS curves, which compose the surface and then in CAM systems the curves are divided into a large number of line or arc segments. These divided movement commands, however, cause many problems including their excessive size of NC data that makes almost impossible local adjustment or modification of the surface. To cope with those problems, the necessity of real-time curve or surface interpolators was embossed. This paper presents an efficient real-time tool-path generation method for interpolation of NURBS surfaces in CNC machining. The proposed tool-path generation method is based on an improved iso-scallop strategy and can provide better precision than the existing methods. The proposed method is designed such that tool-path planning is easily managed in real-time. It proposed a new algorithm, for regulation of a scallop height, which can efficiently generate tool-paths and can save machining time compared with the existing method. Through computer simulations, the performance of the proposed method is analyzed and compared with the existing method in terms of feedrate, total machining time and a degree of constraint on the scallop height.
Journal of Mechanical Science and Technology, 1998
This paper introduces a new cross-coupling controller with a rule-based fuzzy logic control. It i... more This paper introduces a new cross-coupling controller with a rule-based fuzzy logic control. It is asserted that (i) fuzzy logic controllers provide a better transient response (which is essential for better contour accuracy during transient motions) than the conventional controllers, such as PID controllers, and (ii) cross-coupling controllers perform better than axial controllers in trajectory tracking by machine tools. In this paper, a fuzzy logic controller and a cross-coupling controller are combined to reduce contour errors. A simulation of the FLCCC was performed and the FLCCC was implemented on a CNC milling machine. The simulation and the experimental results show improved contour accuracy over the conventional cross-coupling controller.
Current cam design practice, based on acceleration curves defined by trigonometric, polynomial, o... more Current cam design practice, based on acceleration curves defined by trigonometric, polynomial, or spline functions of the rotation angle, yields profiles that require approximation before they can be imported to CAD systems or downloaded to CNC ...
In CAD systems, a surface to be machined is expressed by a series of curves, such as B-spline, Be... more In CAD systems, a surface to be machined is expressed by a series of curves, such as B-spline, Bezier and NURBS curves, which compose the surface and then in CAM systems the curves are divided into a large number of line or arc segments. These divided movement commands, however, cause many problems including their excessive size of NC data that makes almost impossible local adjustment or modification of the surface. To cope with those problems, the necessity of real-time curve or surface interpolators was embossed. This paper presents an efficient real-time tool-path generation method for interpolation of NURBS surfaces in CNC machining. The proposed tool-path generation method is based on an improved iso-scallop strategy and can provide better precision than the existing methods. The proposed method is designed such that tool-path planning is easily managed in real-time. It proposed a new algorithm, for regulation of a scallop height, which can efficiently generate tool-paths and can save machining time compared with the existing method. Through computer simulations, the performance of the proposed method is analyzed and compared with the existing method in terms of feedrate, total machining time and a degree of constraint on the scallop height.
Journal of Mechanical Science and Technology, 1998
This paper introduces a new cross-coupling controller with a rule-based fuzzy logic control. It i... more This paper introduces a new cross-coupling controller with a rule-based fuzzy logic control. It is asserted that (i) fuzzy logic controllers provide a better transient response (which is essential for better contour accuracy during transient motions) than the conventional controllers, such as PID controllers, and (ii) cross-coupling controllers perform better than axial controllers in trajectory tracking by machine tools. In this paper, a fuzzy logic controller and a cross-coupling controller are combined to reduce contour errors. A simulation of the FLCCC was performed and the FLCCC was implemented on a CNC milling machine. The simulation and the experimental results show improved contour accuracy over the conventional cross-coupling controller.
Current cam design practice, based on acceleration curves defined by trigonometric, polynomial, o... more Current cam design practice, based on acceleration curves defined by trigonometric, polynomial, or spline functions of the rotation angle, yields profiles that require approximation before they can be imported to CAD systems or downloaded to CNC ...
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Papers by Sungchul Jee