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김수진(Su Jin Kim),최인휴(In Hugh Choi),양민양(Min Yang Yang) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
NURBS (Non Uniform Rational B-Spline) is widely used in CAD system and NC data for high speed<br/> machining. Conventional CAM system changes NURBS surface to tessellated meshes or Z-map model, and<br/> produces linear tool path. The linear tool path is not good for precise machining and high speed machining. In<br/> this paper, an algorithm to change linear tool path to NURBS one was studied, and the machining result of<br/> NURBS tool path was compared with that of linear tool path. The N-post, post-processing and virtual<br/> machining software was developed. The N-Post post-processes linear tool path to NURBS tool path and<br/> quickly shades machined product on OpenGL view and compares a machined product with original CAD<br/> surface. A virtual machined model of original tool path and post-processed tool path was compared to original<br/> CAD model. The machining error of post-processed NURBS tool path was reduced to 43%. The original tool<br/> path and NURBS tool path was used to machine general model using same machine tool and machining<br/> condition. The machining time of post-processed NURBS tool path was reduced up to 38%.
정태성,최인휴,이동윤,양민양,Jung, Tae-Sung,Choi, In-Hugh,Lee, Dong-Yoon,Yang, Min-Yang 한국기계가공학회 2003 한국기계가공학회지 Vol.2 No.3
In order to reduce the lead-time and cost, many useful methods have been applied to rapid prototyping (RP) in recent years. But cutting process is still considered as one of the effective RP methods that have been developed and currently available in the industry. It also offers practical advantages in aspects of precision and versatility. However, traditional 3-axis NC machining has some inherent limitations such as the restriction of tool accessibility and the complex setup. In this work, a new rapid prototyping system with high speed 5-axis machining of plastics has been developed to overcome those limitations. And cutting experiments were conducted to determine the design factors of the system and the cutting conditions of plastics. The architecture of developed system is described in detail and the successful application examples are presented.
황삭가공에서 채터링 및 가공형상을 고려한 공구길이 선정
이철수(Cheol-Soo Lee),허은영(Eun-Young Heo),이동윤(Dong-Yoon Lee),김동수(Dong-Soo Kim),최인휴(In-Hugh Choi) (사)한국CDE학회 2013 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2013 No.1
In 3(5)-axis cutting machining, the tool information is offered to the machining strategy as basic information and affects directly on the productivity and the machining quality. As a tool is heavier and shorter, the flexibility decreases and, consequently, the material removal rate can be increased. To utilize this merit, tool should be selected under machining feature recognition while the machining feature is the shape of machining area. For illustration, the machining area may be divided into several regions at rough machining stage to improve the efficiency. Consequently, each sub machining region requires optimized tool length (overhang). This paper presents a methodology to identify the best tool length for each machining region considering the dynamic characteristics of machine tool. The proposed method was validated by using cutting simulation.
이철수(Cheol-Soo Lee),최인휴(In-Hugh Choi),허은영(Eun-Young Heo),김종민(Jong-Min Kim) 대한산업공학회 2012 대한산업공학회지 Vol.38 No.3
The Electric discharge machining (EDM) process is used to minimize the difference between designed feature and machined feature while the most workpiece is removed through the cutting processes. The tiny-deep hole machining and perpendicular wall machining in mold and die are good applications of EDM. Among EDM equipment, the super drill uses the hollowed electrode to eliminate the debris which causes the second discharge with the electrode and degrades the machining quality. Through the hollow, the high pressured discharge oil is supplied to remove the debris together with the spindle rotation. The thin-hollow electrode tends to easily wear out compared to the sold die-sinking electrode and its wear rate is might not allowed to monitor in real time during discharging. Up to now, the wear amount is measured by off line method, which leads machining time to increase because the hole pass-through moment can be check by visual (manually) with the extra tool path. Therefore, this study suggests the attractive method to evaluate the hole pass-through moment in which the gap voltage and z-axis encoder pulse are monitored to predict the moment. The commercial super drill is used to validate the proposed method and the experiment is carried out.
이철수(Cheol-Soo Lee),최인휴(In-Hugh Choi),최용찬(Young-Chan Choi),김종민(Jong-Min Kim),허은영(Eun-Young Heo) 대한산업공학회 2013 대한산업공학회지 Vol.39 No.3
Electric discharging machining (EDM) is commonly adopted to machine the precise and tiny part when it is difficult to meet the productivity and the tolerance by the conventional cutting method. The die-sinking EDM method works well to machine the micro-parts and the perpendicular wall of die and mould, whereas EDM drilling, called super drill, is excellent to machine the deep and narrow hole regardless the material hardness and the hole location. However, the electrode wear is rapid compared to the conventional cutting tool and makes it difficult to control the electrode feeding and to machine precisely. This paper presents an efficient method to estimate the electrode wear using hole pass-through experiment while the stochastic method is used to compensate for the estimation model. To validate the proposed method, the commercial EDM drill machine is used. The experiment result shows that the electrode wear amount can be predicted very precisely.
이철수(Cheol-Soo Lee),이희승(Hee-Seung Lee),최인휴(In-Hugh Choi),허은영(Eun-Young Heo),김종민(Jong-Min Kim) (사)한국CDE학회 2012 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2012 No.2
Today, machine vision is widely spread in manufacturing applications such as tool monitoring, workpiece recognition, collision detection, and measuring and inspection, offering digitized information to manufacturing systems. The main process of machine visioning consists of several steps: i) object image obtaining, ii) image processing and analysis, iii) feedback of image information to a control system, and iv) actuator manipulation. Especially, in the case of recognizing printed 2D shapes and generating machining data, the image processing and analysis step affects much to manufacturing quality and shop floor productivity. For instance, the patterns of a cover lens of a mobile phone camera are printed into a tempered glass, being measured through a vision system. Machining data for the camera lens is then generated by image processing and analysis. However, thermal effects and printing machine resolution force printed shapes to get errors such as irregular arrangement, rotated patterns, miss-printed patterns, and so on. Thus, this paper identifies the patterns of errors occurred in the image processing and analysis step, proposing an error compensation method based on error patterns for vision based manufacturing systems. A prototype vision-based manufacturing system is shown.