• Title, Summary, Keyword: NURBS

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Variable Feedrate Interpolator for NURBS Curve Considering Material Removal Rate (소재 제거율을 고려한 이송속도 가변형 NURBS 보간기)

  • 마르첸코티혼;고태조;김희술;김정현
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.12 no.2
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    • pp.1-8
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    • 2003
  • Conventionally used linear or circular interpolator is undesirable for the precision machining of 3D free-form surface as the following reason: the transmission errors due to the huge number of data, discontinuity of segmentation, unsmooth motion speed. To this regard, modern CNC machine tools are designed with the function of machining arbitrary parametric curves. However, these systems don't consider the adaptive federate, which dominates the quality of the machining process. This paper proposes a NURBS interpolator for the constant material removal rate. That is accomplished by the variable federate using curvature of curve. The curvature-compensated feederate system has important Potential applications in ensuring part accuracy and protecting cutting tool. The simulated result show it can be applicable to the real machining.

Investigation on the Description Method of Extrusion Die Surface using NURBS Surface Scheme (NURBS 곡면기법을 이용한 압출금형 곡면의 표현방법에 관한 연구)

  • 유동진;임종훈
    • Transactions of Materials Processing
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    • v.12 no.2
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    • pp.151-160
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    • 2003
  • In the present study, an advanced surface construction method based on NURBS surface scheme is proposed to construct the extrusion die surface. The inlet and outlet profiles we precisely described with NURBS curves using the cubic appropriate control points and weights. The interior control Points of surface are generated using the cubic interpolation of the weights at the inlet and outlet sections. In order to verify of the proposed method, automatic surface generation is carried out for the various types of extrusion die surface.

NURBS Interpolator for Controlling the Surface Roughness (표면 거칠기를 고려한 NURBS 보간기)

  • 최인휴;양민양;이강주
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.162-167
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    • 2003
  • Finish machining of a curved surface is often carried out by an NC system with curve interpolation in the field. This NURBS interpolation adopts a feedrate optimizing strategy based on both the geometrical information and dynamic properties. In case of a finish cut using a ball-end mill. the curve interpolator needs to take the machining process into account for more improved surface, while reducing the polishing time. In this study, the effect of low machinability at the bottom of a tool on surface roughness is also considered. A particular curve interpolation algorithm is proposed for generating feedrate commands which are able to control the roughness of a curved surface. The simulation of the machined surface by the proposed algorithm was carried out, and experimental results are presented.

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NURBS Interpolator for Controlling the Surface Roughness (표면 거칠기를 고려한 NURBS 보간기)

  • Choi, In-Hugh;Jung, Tea-Sung;Hong, Won-Pyo;Yang, Min-Yang
    • Proceedings of the KSME Conference
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    • pp.1226-1233
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    • 2003
  • Finish machining of a curved surface is often carried out by an NC system with curve interpolation in the field. This NURBS interpolation adopts a feedrate optimizing strategy based on both the geometrical information and dynamic properties. In case of a finish cut using a ball-end mill, the curve interpolator needs to take the machining process into account for more improved surface, while reducing the polishing time. In this study, the effect of low machinability at the bottom of a tool on surface roughness is also considered. A particular curve interpolation algorithm is proposed for generating feedrate commands which are able to control the roughness of a curved surface. The simulation of the machined surface by the proposed algorithm was carried out, and experimental results are presented.

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A Study on the Generation of Ship Hull Lines Using NURBS Method (NURBS 기법을 이용한 선체선도 형성에 관한 연구)

  • 이동기
    • Journal of Ocean Engineering and Technology
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    • v.14 no.1
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    • pp.95-101
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    • 2000
  • In general, free form design depends on B-spline which is used for the generating hull lines in most of shipyards. But, nowadays, the NURBS method is applied to free form modeling method, which is able to more flexible transformation than B-Spline, and then became industrial standard in the various field. Therefore, this method has been considerably applied in new application fields which are required free form modelling. In this paper, the program called 2DSURF with 5 modules and developed for the generation of hull lines is described. It is examined whether the program can be applied to body lines, sheer lines, and half breadth lines.

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Shape Design Optimization of High-Speed Air Vehicles Using Non-Uniform Rational B-Splines (NURBS 곡선을 이용한 고속비행체 최적형상설계)

  • Kim Sang-Jin;Lee Jae-Woo;Byun Yung-Hwan;Kim Myung-Seong
    • 한국전산유체공학회:학술대회논문집
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    • pp.72-77
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    • 2001
  • The computational efficiency of an shape optimization procedure is highly dependent upon the proper selection of shape representation methods and design variables. In this study, shape functions, Bezier and NURBS(non-uniform rational B-splines) curves are selected as configuration generation methods and their efficiencies on the nose shape design of high-speed air vehicles, are compared. The effects of the number of control points, weighting factors and the optimization methods when utilizing the NURBS curves, are investigated. By implementing Bezier and NURBS curves, shapes having lower drag than the optimization case utilizing the shape functions, were obtained, hence it was demonstrated that these curves have better capability in representing the configuration. Efforts will be given to improve the convergence behavior when utilizing the NURBS, hence to reduce the number of Navier-Stokes analysis calculations.

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Calculation of NURBS Curve Intersections using Bzier Clipping (B$\acute{e}$zier클리핑을 이용한NURBS곡선간의 교점 계산)

  • 민병녕;김재정
    • Korean Journal of Computational Design and Engineering
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    • v.3 no.2
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    • pp.113-120
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    • 1998
  • Calculation of intersection points by two curves is fundamental to computer aided geometric design. Bezier clipping is one of the well-known curve intersection algorithms. However, this algorithm is only applicable to Bezier curve representation. Therefore, the NURBS curves that can represent free from curves and conics must be decomposed into constituent Bezier curves to find the intersections using Bezier clipping. And the respective pairs of decomposed Bezier curves are considered to find the intersection points so that the computational overhead increases very sharply. In this study, extended Bezier clipping which uses the linear precision of B-spline curve and Grevill's abscissa can find the intersection points of two NURBS curves without initial decomposition. Especially the extended algorithm is more efficient than Bezier clipping when the number of intersection points is small and the curves are composed of many Bezier curve segments.

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NURBS Surface Rendering of Sculpting Effect Using Multiresolution Surface Trimming for Spatial Virtual Design (공간 가상 디자인을 위한 다해상도 곡면트리밍을 이용한 넙스곡면 조각효과 렌더링)

  • Kwon, Jeong-Hoon;Kim, Hee-Jun;Chai, Young-Ho
    • Korean Journal of Computational Design and Engineering
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    • v.11 no.6
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    • pp.403-411
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    • 2006
  • NURBS surfaces have been widely used in engineering design since it can create a smooth surface using minimal numbers of data. But deformation of the surfaces is quite difficult especially for the detailed modification. Also, NURBS surface deformation processes need many inputs, and it is not easy to be implemented in 3D virtual system. In this paper, both the surface trimming and multi-resolution surface are used for the detailed sculpting including sharp edges of NURBS surface. QuadTree is used to separate cleanly the target surface with the surface for sculpting effect. Simple user strokes are also used for the sculpting target curves and GOMS(Goals, Operators, Methods, Selection Rules) model is applied to verify the efficiency of the proposed sculpting process.

Analytic and Discrete Fairing of 3D NURBS Curves (3D NURBS 곡선의 해석적 및 이산적 순정)

  • 홍충성;홍석용;이현찬
    • Korean Journal of Computational Design and Engineering
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    • v.4 no.2
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    • pp.127-138
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    • 1999
  • For reverse engineering, curves and surfaces are modeled for new products by interpolating the digitized data points. But there are many measuring or deviation errors. Therefore, it is important to handle errors during the curve or surface modeling. If the errors are ignored, designer could get undesirable results. For this reason, fairing procedure with the aesthetics criteria is necessary in computer modeling. This paper presents methods of 3D NURBS curve fairing. The techniques are based on automatic repositioning of the digitized dat points or the NURBS curve control points by a constrained nonlinear optimization algorithm. The objective function is derived variously by derived curved. Constraints are distance measures between the original and the modified digitized data points. Changes I curve shape are analyzed by illustrations of curve shapes, and continuous plotting of curvature and torsion.

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The Development of 3D Gauge Curve Generation Method using NURBS Curve in Shoe Sole modeling (NURBS곡선을 이용한 3D Gauge 곡선의 모델링 기술 개발)

  • 배태용
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.317-322
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    • 2004
  • Productivity of shoe industry in Korea is still more excellent then that of China or Vietnam, But manufacturing technology and productive facility are underdevelopment in comparison advanced country. CAD/CAM system development, one of the most important technology, is totally nonexistent. specially, the automatic generation function and the grading function in shoe sole modeling are dependent of the foreign software. The CAD/CAM software only for shoe modeling is very expensive, so that it is going to weaken shoe industry of Korea. Therefore, We developed 3D gauge curve generation method using 2D NURBS curve in shoe sole modeling.

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