• 대한기계학회논문집A
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• 제24권4호
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• pp.937-945
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• 2000

The assessment of machined surface is difficult because the freeform surface must be evaluated by surface fairness as well as dimensional accuracy. In this study, the machined freeform surface is modeled by interpolating the data measured on the machine tool into the mathematical continuous surface, and then the surface model is improved with the parameterization to minimize surface fairness. The accuracy reliability of the measured data is confirmed through compensation of volumetric errors of the machine tool and of probing errors. Non-uniform B-spline surface interpolation method is adopted to guarantee the continuity of surface model. Surface fairness is evaluated with the consideration of normal curvature on the interpolated surface. The validity and usefulness of the proposed method is examined through computer simulation and experiment on the machine tool.

• 대한조선학회논문집
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• 제31권2호
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• pp.15-21
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• 1994

전산기를 이용한 순정작업은 크게 두 가지로 구분할 수 있다. 첫번째는 단면곡선, 즉 2차원 곡선을 순정하고 다른 단면에서도 역시 부드러운가를 확인하는 전통적인 방법이다. 두번째는 곡면을 이용하는 것으로 전산기의 발달과 더불어 최근 많이 사용하고 있는 방법이다. 그러나 이 경우 먼저 선형을 곡면으로 정의하여야 하나 복잡한 선형의 경우 쉽지가 않다. 본 연구에서는 곡선의 순정기법을 확장하여 그물망 곡선(mesh curve)의 경우에 대해 비균일(non-uniform) B-Sp line 곡선을 이용한 Rong의 방법으로 선형의 순정작업을 행하였다. 그러나 Rong의 방법에는 곡선의 양 끝점에서의 기울기가 고정되어야 하는 제한이 있으며 곡면화 방법에 대한 기술이 명확하지 못하다. 본 연구에서는 곡선의 양끝의 기울기를 고정시키지 않고 순정작업을 할 수 있도록 하였으며, 순정된 결과를 곡면화하는 방법을 제안하였다.

• 대한기계학회논문집A
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• 제27권8호
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• pp.1418-1425
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• 2003

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 fur 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 federate, total machining time and a degree of constraint on the scallop height.