• Title/Summary/Keyword: NC Machining

### The Generation of a Smooth C Extension Surface (부드러운 $C^2$확장 곡면 생성)

• 김회섭
• Korean Journal of Computational Design and Engineering
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• v.9 no.2
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• pp.143-147
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• 2004
• To design parts satisfying physical property in the continuous region, we do it in the discrete rectangular mesh points. Then we obtain points data from parts design and usually construct the surface using least squares method. In such case, that surface has an oscillation in the ineffective region which is inadequate for physical phenomena or NC machining. To solve both problems simultaneously, we extend the surface smoothly to have small curvature in the extended region. Up to now, we use the least squares method for the parts design in Color Picture Tube or Color Display Tube but in this paper, we use functions which is easily controllable. This surface has no error within the effective region compared to the least squares method.

### Offsetting Curves Using Trigonometric Splines for Contour Cutting (윤곽 가공을 위한 삼각 스플라인을 이용한 오프셋 곡선의 생성)

• Gu, Jiu-long;Yun, Jae-Deuk;Jung, Yoong-Ho
• Korean Journal of Computational Design and Engineering
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• v.15 no.4
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• pp.253-260
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• 2010
• This paper presents algorithms for computing offsets of freeform curves. The approach first divides the original curve into several segments at the inflexion points. Based on the obtained new control polygon and its offsets, quadratic trigonometric splines are constructed to approximate the offset curves. Finally, the shape parameter value of trigonometric spline is determined to satisfy the required tolerance. The degree of the output curve is two, independent of the original curve's degree. Because of the great controllability, the proposed method can generate a completely overestimating offset curve by adjusting the value of the shape parameter, which guarantees no overcutting in NC machining. Furthermore, it also produces the lowest number of control points compared with other works.

### STEP-NC Repository for STEP-Compliant CNC (STEP-Compliant CNC를 위한 STEP-NC Repository구축)

• 김준환;천상욱;한순흥
• Korean Journal of Computational Design and Engineering
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• v.8 no.1
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• pp.48-54
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• 2003
• In a design-to-manufacturing environment, the product data is shared by various CAD/CAM/CAE systems with little integration or substantial data redundancy. The main purpose of this paper is to build a database containing all the features required for STEP-NC machining and to show how a STEP-NC repository can support the complete process for machining. A STEP-NC database schema has been constructed and several query functions have been built for the purpose of implementing the retrieving system of a STEP-NC database. The EXPRESS data model of ISO 14649 has been mapped to the database data definition language of the Oracle database. To apply the STEP-NC database to an industry example, the ISO 14649 part program has been stored into the STEP-NC database. To implement example scenarios, the sample query interface has been built.

### Generation of Tool Paths for NC Machining of 3D Surfaces by Measurement Data (3차원 측정 곡면의 효율적인 NC 가공을 위한 공구 경로 생성)

• 구영희
• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.10a
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• pp.207-212
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• 1997
• The purpose of this study is the development of CAM system which can cut and measure any shape by machining center and coordinate measuring machine. The overall goal of the CAM system is to achieve the CNC machining, from digitizing through to final cutting. The hardware of the system comprises PC and machining center, CMM. There are three steps in the CNC machining, (1) workpiece measuring on the CMM, (2) geometric modeling by the CAD system, (3) NC commands generation by the tool path compensated for tool nose radius. It is developed a software package, with which can conduct a micro CAM system in the PC without economical burden.

### A study on plastic mold design for robot shape and mold manufacture (로봇형상 플라스틱금형설계 및 제작에 관한 연구)

• Kim, Sei-hwan;Choi, Kye-kwang
• Design & Manufacturing
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• v.6 no.2
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• pp.64-69
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• 2012
• This study looks at plastic mold design for robots and mold manufacture, which is an injection mold branch at The Korea-China-Japan University Grand Prize Contest. Product analysis and layout, molding analysis, and upper and lower core design are carried out to design molds in 2D and 3D. After the design of the cores, NC machining software is used for simulation before actual manufacture. Before the production of end-product, test injection is done to troubleshoot problems like bad dimensions, burr, cracks and stepped pulley.

### A study on the effects of second cut on the roughness of surfaces treated with wire-cut electric discharge machining (W-EDM) (2차 가공이 와이어 컷 방전가공면 표면조도 분포에 미치는 영향에 관한 연구)

• Kim, Sei-hwan;Choi, Kye-kwang
• Design & Manufacturing
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• v.6 no.1
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• pp.58-62
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• 2012
• Unlike conventional single special cut methods, W-EDM is a combination of multiple-effects. This study focuses on the effects of second cut on the roughness of surfaces treated with W-EDM. W-EDM is, to a large extent, typical unmanned-machining equipment, which represents NC machining equipment that allows long-time full automation. W-EMD is getting popular as a precise machining technology and STD11 is frequently used in press die manufacture. In this study, the former is applied to the latter to look at the effects of second cut on the roughness of surfaces treated with W-EDM.

### Interference-free tool path generation for 5-axis NC machining with ball-endmill (5축 볼 엔드밀 가공에서의 간섭이 배제된 공구경로 산출)

• 강대호;서석환;이정재
• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.95-100
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• 1993
• 본 연구에서는 볼 엔드밀을 사용한 5축 가공에서 공구 간섭회피를 위한 효율적인 알고리즘과 가공 가능한 많은 자세들 중에서 공구 절삭부위와 이전자세를 고려한 공구 자세설정 알고리즘을 개발 하였다. 공구 간섭검사는 공구 밑면 간섭과 몸체 간섭으로 나누어 순차적으로 수행하고, 공구 몸채 간섭이 없는 공구 자세를 설정한다. 공구 몸체 간섭검사는 곡면의 다각형 모델과 공구 축과의 관계를 사용하여 행한다. 간섭이 발생하였을 경우 간섭회피 및 자세조정 영역으로 설정하고 유효한 공구자세의 범위를 정한 후, 이 범위 내에서 공구 절삭 부위 및 이전 자세를 고려한 효율적 공구자세를 사용하여 공구경로를 산출하였으며, 시뮬레이터를 통해 그 유효성을 검증하였다.

### Offset of STL Model Generated from Solid Model (솔리드 STL 모델의 옵셋 방법)

• Kim, Su-Jin;Yang, Min-Yang
• Journal of the Korean Society for Precision Engineering
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• v.22 no.9 s.174
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• pp.202-211
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• 2005
• This paper introduces and illustrates the results of a new method fer offsetting triangular mesh by moving all vertices along the multiple normal vectors of a vertex. The multiple normal vectors of a vertex are set the same as the normal vectors of the faces surrounding the vertex, while the two vectors with the smallest difference are joined repeatedly until the difference is smaller than allowance. Offsetting with the multiple normal vectors of a vertex does not create a gap or overlap at the smooth edges, thereby making the mesh size uniform and the computation time short. In addition, this offsetting method is accurate at the sharp edges because the vertices are moved to the normal directions of faces and joined by the blend surface. The method is also useful for rapid prototyping and tool path generation if the triangular mesh is tessellated part of the solid models with curved surfaces and sharp edges. The suggested method and previous methods are implemented on a PC using C++ and illustrated using an OpenGL library.

### Development of Machining Simulation System using Enhanced Z Map Model (Enhanced Z map을 이용한 절삭 공정 시뮬레이션 시스템의 개발)

• 이상규;고성림
• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.551-554
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• 2002
• The paper discusses new approach for machining operation simulation using enhanced Z map algorithm. To extract the required geometric information from NC code, suggested algorithm uses supersampling method to enhance the efficiency of a simulation process. By executing redundant Boolean operations in a grid cell and averaging down calculated data, presented algorithm can accurately represent material removal volume though tool swept volume is negligibly small. Supersampling method is the most common form of antialiasing and usually used with polygon mesh rendering in computer graphics. The key advantage of enhanced Z map model is that the data structure is same with conventional Z map model, though it can acquire higher accuracy and reliability with same or lower computation time. By simulating machining operation efficiently, this system can be used to improve the reliability and efficiency of NC machining process as well as the quality of the final product.

### 자유곡면의 측정 및 공구경로산출을 위한 프로브반경보정 연구

• 이성권;서석환
• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.10a
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• pp.71-76
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• 2001
• In the surface measurement system using touch probe, probe radius compensation is a key factor for accuracy. In this paper we investigate methods for compensating probe radius so that the surface equation for an "unknown surface" can be efficiently derived. The developed algorithm derives the surface equation by the iterative procedure of estimation, verification, and modification . Since the procedure is applied only for the surface region exceeding the tolerance limit, an accurate surface equation can be obtained with less computation and measurement point. The validity and effectiveness of the algorithm was tested by numerical simulations. The results convinced us that the develop algorithm can be used for surface measurement and tool path planning for NC machining.