• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.815-820
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• 1991

4축 자유곡면가공에 있어서 공구간섭 문제는 가공형상의 취득성 뿐만 아니라 가공의 정밀도를 위하여 매우 중요한 고려사항이다. 공구의 접근자세가 고정된 3축 밀링가공의 공구 간섭에 관한 기존의 많은 연구가 있지만 이러한 연구는 공구의 접근자세가 변하는 4축 밀링가공에의 적용이 곤란하다. 왜냐하면 곡면의 형상에 따라 공구몸체의 곡면사이의 간섭문제가 부각되며, 이에 따른 공구자세의 창출문제가 해결되어야 하기 때문이다. 따라서 본 논문에서는 4축가공에서 발생할 수 있는 공구 간섭을 유형별로 분류, 각 간섭들을 발견하고 해결할 수 있는 방법의 전개와 이 방법을 이용하여 공구경로를 산출하고 그래픽 시뮬레이션과 실제의 시험절삭을 통하여 제시된 방법의 유효성을 검증한다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.100-106
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• 2021

This paper presents a study on the improvement of the machining quality of sculptured-surfaces of molds according to the shape and posture of the tool. In the existing 3-axis machining, the methods using the ball end-mill and radius end-mill were analyzed for various cutting patterns and compared with those of the 5-axis machining. It was observed that the 5-axis machining using a ball end-mill obtained the finest surface roughness, and for the 3-axis machining, the optimal results were obtained for the one-way machining using a radius end-mill.

• Journal of Korea Society of Industrial Information Systems
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• v.9 no.1
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• pp.7-16
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• 2004

The tool path needs to be determined in an efficient manner to generate the final NC (numerical control) code for efficient machining. This is particularly important in machining free form pockets with an arbitrary wall geometry on a three-axis CNC machine. Many CAD/CAM systems use linear interpolation to generate NC tool paths for curved surfaces. However, this needs to be modified to improve the smoothness of the machined bottom surface, reduce machining time and CL (cutter location) file size. Curved machining can be a solution to reduce these problems. The unified rough and finish cut algerian and the tool motion is graphically simulated. In this paper, a grid based 3D navigation algorithm for generating NC tool path data for both linear interpolation and a combination of linear and circular interpolation for three-axis CNC milling of general pockets with sculptured bottom surfaces is developed.

• Journal of Korea Society of Industrial Information Systems
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• v.12 no.1
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• pp.46-53
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• 2007

NC (Numerical Control) code for the tool path needs to be generated efficiently for machining of free form pockets with arbitrary wall geometry on a three axis CNC machine. The unified rough and finish cut algorithm and the tool motion is graphically simulated in Part 1. In this paper, a grid based 3D navigation algorithm simulated in Part 1 for generating NC tool path data for both linear interpolation and a combination of linear and circular interpolation for three-axis CNC milling of general pockets with sculptured bottom surfaces is experimentally performed and verified.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.134-140
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• 2017

Shape-from-shading (SFS) or stereo vision algorithms can be utilized to measure the shape of an object with imaging techniques for effective sensing in non-contact measurements. SFS algorithms could reconstruct the 3D information from a 2D image data, offering relatively comprehensive information. Meanwhile, a stereo vision algorithm needs several feature points or lines to extract 3D information from two 2D images. However, to measure the size of an object with a freeform surface, the two algorithms need some additional information, such as boundary conditions and grids, respectively. In this study, a stereo vision scheme using the depth information obtained by shape-from-shading as patterns was proposed to measure the size of an object with a freeform surface. The feasibility of the scheme was proved with an experiment where the images of an object were acquired by a CCD camera at two positions, then processed by SFS, and finally by stereo matching. The experimental results revealed that the proposed scheme could recognize the size and shape of freeform surface fairly well.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.469-473
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• 2003

Milling 가공시 공구와 피삭재의 접합명에서는 절삭가공의 잔유물인 burr가 생성되고, 이러한 Burr는 작업효율과 정밀도를 감소시키며 추처리과정 (Deburring)을 야기시키는 원인이 된다. 그러므로 정밀도와 작업효율을 극대화하기 위해서는 이러한 Burr의 생성원리를 파악함과 동시에 Exit Burr의 여부에 대한 판별을 하여 최적의 가공조건을 맞추어 주어야 하는데, 이러한 경우에 지금까지는 점, 선 및 원으로 피삭재의 형상을 재현하여 공구의 경로와의 Exit 각을 통해 결과를 예측하는 연구를 해왔었다. 본 논문에서 추구하고자 하는 핵심은 이러한 피삭재의 형상을 재현하기 위해 지금까지 사용해왔던 요소를 보다 다양화시키는 방안을 제시하여 프로그램의 적용 범위를 넓히려는 것이다. 예컨대 이제까지 실제 가공에서 사용되고 있는 임의형상에 대한 표현 방식 중에서 대다수 CAD 프로그램에서 곡선 및 곡면을 표현하는 경우, B-Spline Curve의 알고리즘은 패삭재의 불규칙적인 곡면을 가장 근사하게 표현하는 최적의 해결책으로 쓰여지고 있다. 그러므로 이러한 알고리즘을 통해 프로그램의 적용예를 넓히는 것은 보다 다양한 조건에서의 Burr생성에 대한 예측을 가능케 해주는 것이다. 본 논문에서는 앞에서 언급한 바와 같이 B-Spline Curve 알고리즘을 개발하고, 프로그램에 적용하는 일련의 과정을 통해 보다 다양한 형상의 피삭재에서 단일 혹은 복합경로의 공구가 지나갈 경우에 생길 수 있는 Burr를 얼마나 효율적으로 판별할 수 있는지를 소개하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.3
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• pp.259-264
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• 2012

Automatic magnetic abrasive polishing (MAP), which can be applied after machining of a mold on a machine tool without unloading, is very effective for finishing a free-form surface such as a complicated injection mold. This study aimed to improve the efficiency of MAP of a non-ferrous mold surface. The magnetic array table and control of the electromagnet polarity were applied in the MAP of a free-form surface. In this study, first, the magnetic flux density on the mold surface was simulated to determine the optimal conditions for the polarity array. Then, the MAP efficiency for polishing a non-ferrous mold surface was estimated in terms of the change in the radius of curvature and the magnetic flux density. The most improved surface roughness was observed not only in the upward tool path but also in the working area of larger magnetic flux density.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.1
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• pp.78-87
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• 2001

This paper deals with the study on the cutting characteristics in ball-end milling process. First of all, the effects of the geometric cutting conditions such as the cutting speed, feedrates and the path interval on the surface integrity were evaluat-ed by the analytical and the experimental approaches. Secondly, the cutting mechanism model was developed to predict the cutting force accurately. It is possible for the proposed model to predict the shape error, estimate system stability and build the reliable adaptive control system. A large amount of experimental set are performed to show the validities of the proposed theories and to investigate the effect of cutting geometry such as rubbing effects, burr effects and etc.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.155-155
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• 2004

최근 집중 육성산업으로 분류되어 연구 및 투자가 되고 있는 반도체, 정보통신, 바이오산업, 디스플레이 등에서 초정밀화와 저비용, 대량생산을 하기 위해서 기존의 공정을 대체할 수 있는 새로운 나노공정기술의 요구가 급증하고 있다 최근에는 극초단파 특성으로 인하여 극미세 형상을 가공할 수 있는 펨토초 레이저(femto second laser)를 나노공정에 적용하는 다양한 연구가 진행되고 있다. 특히, 기존의 쾌속조형공정을 응용하여 다른 공정으로는 제작이 불가능한 나노 스케일에서 3차원 자유곡면을 가지는 구조물을 제작할 수 있는 공정개발에 대하여 다양한 연구가 진행되고 있다.(중략)

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.753-759
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• 2001

The purpose of this study is to suggest the machining technique of the constant control of cutting speed in order to improve precision machining and tool life in high speed machining using ball end mill. Cutting speed is changed in machining free form surface like free form surface. So, we don't have supreme surface form and toll life on machining. The way to solving this problem is that we should be settled to optimal cutting speed in free form surface machining. And, to improve precision machining is executed high speed machining method to output optimum NC data with developed constant control of cutting speed program after modeling of CAD/CAM. In this paper, a comparison was made of the cutting precision and tool life in conventional cutting and those in free form surface machining applying the program developed.