• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1991년도 춘계공동학술대회 발표논문 및 초록집; 전북대학교, 전주; 26-27 Apr. 1991
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• pp.124-130
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• 1991

5-axis NC machining of sculptured surface using non-ballendmill cutters (eg. facemilling cutters) is widely used in the machining of turbine blades and marine propellers. Since there are more degrees of freedom in 5-axis machining than in 3-axis machining, generating "optimum" cutter paths and finding desirable cutter positions become very important in order for an efficient use of 5-axis NC machines. Also critical in 5-axis NC machining are collision avoidance, gouging checking, and efficient kinematic solutions. In this paper we discuss the above issues in generating 5-axis CL data. They are : kinematics modeling of NC machine; inverse kinematics solution; interference between machine component and surface; cutter gouging. A unique search method for obtaining optimal CL data is proposed. The proposed method has been successfully implemented in the machining of marine propellers on a dual 5-axis (ie, 9-axis) NC machine.C machine.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.199-204
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• 1994

A method for determining the collision-free tool orientation for 5-axis milling is presented. In 5-axis milling, the proper tool orientation as well as the optimal CC-data has to be selected to machine the workpiece efficiently and accurately and accurately. Essentially, the tool orientation should be determined to avoid collisions between the tool and workpiece and to enable efficient machining. In this work, the tool orientation is determined at every CC-point which is assumed to be given. The procedure uses the potential energy method that assumes the tool and the part surfaces are charged with static electricity. This approach can detect can deteat both global and local collisions (gouging) irrespective of the tool shape. Further, in order to increase the machining efficiency, the material removal rate is maximized simultaneously.

• 동력기계공학회지
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• 제18권4호
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• pp.85-90
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• 2014

In this paper, the transient thermal and residual stress analysis of the welding of 9% Ni steel plates using the FEA software ABAQUS are presented. The 9% Ni steel plates are welded manually with welding consumables of 70% Ni based Inconel type super-alloys (YAWATA WELD B (M)), producing a multi-pass/multi-layer butt weld. For these materials, temperature dependant mechanical and thermal material properties are used in the analysis. The back gouging is considered in welding process simulation. The FE thermal results are validated by comparing the real fusion profile and heat affected zone (HAZ). In addition, the continuous indentation test was conducted to measure the strength of base metal, HAZ and weld metal.

• 대한산업공학회지
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• 제19권3호
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• pp.123-137
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• 1993

In this paper, an integrated approach is proposed to generate gouging-free Cartesian tool paths for machining sculptured surfaces from 3D measurement data. The integrated CAD/CAM system consists of two modules : offset surface module an Carteian tool path module. The offset surface module generates an offset surface of an object from its 3D measurement data, using an offsetting method and a surface fitting method. The offsetting is based on the idea that the envelope of an inversed tool generates an offset surface without self-intersection as the center of the inversed tool moves along on the surface of an object. The surface-fitting is the process of constructing a compact representation to model the surface of an object based on a fairly large number of data points. The resulting offset surtace is a composite Bezier surface without self-intersection. When an appropriate tool-approach direction is selected, the tool path module generates the Cartesian tool paths while the deviation of the tool paths from the surface stays within the user-specified tolerance. The tool path module is a two-step process. The first step adaptively subdivides the offset surface into subpatches until the thickness of each subpatch is small enough to satisfy the user-defined tolerance. The second step generates the Cartesian tool paths by calculating the intersection of the slicing planes and the adaptively subdivided subpatches. This tool path generation approach generates the gouging-free Cartesian CL tool paths, and optimizes the cutter movements by minimizing the number of interpolated points.

• 한국정밀공학회지
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• 제15권8호
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• pp.46-59
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• 1998

This paper presents shape design, surface construction, and cutting path generation for the surface of marine ship propeller blades. A propeller blade should be designed to satisfy performance constraints that include operational speed which impacts rotations per minutes, stresses related to deliverable horst power, and the major length of the marine ship which impacts the blade size and shape characteristics. Primary decision variables that affect efficiency in the design of a marine ship propeller blade are the blade diameter and the expanded area ratio. The blade design resulting from these performance constraints typically consists of sculptured surfaces requiring four or five axis contoured machining. In this approach a standard blade geometry description consisting of blade sections with offset nominal points recorded in an offset table is used. From this table the composite Bezier surface geometry of the blade is created. The control vertices of the Hazier surface patches are determined using a chord length fitting procedure from tile offset table data. Cutter contact points and path intervals are calculated to minimize travel distance and production time while maintaining a cusp height within tolerance limits. Long path intervals typically generate short tool paths at the expense of increased however cusp height. Likewise, a minimal tool path results in a shorter production time. Cutting errors including gouging and under-cut, which are common errors in machining sculptured surfaces, are also identified for both convex and concave surfaces. Propeller blade geometry is conducive to gouging. The result is a minimal error free cutting path for machining propeller blades for marine ships.

• 대한안전경영과학회지
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• 제6권1호
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• pp.283-300
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• 2004

This paper describes the NC simulator system for Wire-cut electrodischarge machining. Electrodischarge Wire-cut machining is applicable to all materials including metals, alloys, and most carbides. Although CAM system generate the NC code considering electrodischarge conditions, incorrect Wire-cut tool path bring about fatal results. The simplest way of simulating a EDM process is to display the trajectory of Wire-cutter location by line segments. With this kind of simulation, the programmer can get a general idea about whether the wire is moving as planned but cannot locate gouging or excess material because only the wire location will be seen, not the changes in the workpiece as it is machined. The ideal way of simulating the EDM process is to display the solid model of the workpiece as it is machined. Therefore we propose the ideal NC simulator system for Wire-cut EDM.

• 대한산업공학회지
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• 제19권3호
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• pp.139-154
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• 1993

Cutter Interference(or part surface gouging) is one of the most critical problems in NC machining of sculptured surfaces. Presented in this paper is and algorithmic procedure that converts CC data obtained from a compound surface(several surfaces without topological relationship) into interference-free CL data. The interference handling procedure consists of following steps: (1) Z-map model is constructed from input surfaces. (2) Interference sources are detected using local properties of the sources. (3) Interference regions are completely identified based on global tests for neighboring CC points of the interference sources (4) Cutter paths are reconstructed after removing the CC data in interference regions, while avoiding any new interferences.

• Journal of Mechanical Science and Technology
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• 제16권9호
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• pp.1033-1039
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• 2002

Partial penetration welding joint refers to the groove weld that applies to the one side welding which does not use steel backing and to both side welding without back gouging, that is, the partial penetration welding joint leaves an unwelded portion at the root of the welding area. In this study, we analyzed the residual stress and fracture on the thick metal plates that introduced the partial penetration welding method. According to the above-mentioned welding method, we could draw a conclusion that longitudinal stress and traverse stress occurred around the welding area are so minimal and do not affect any influence. We also performed the fracture behavior evaluation on the partial penetration multi pass welding with 25.4 mm thick plate by using the J-integral, which finally led us the conclusion that the partial penetration multi-pass welding method is more applicable and effective in handling the root face with less than 6.35 mm.

• Journal of Welding and Joining
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• 제2권1호
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• pp.1-3
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• 1984

$CO_2$ 편면 용접은 편면 잠호 용접과 함께 작업 능률 향상, 작업 환경 개선 등의 잇점을 가지고 있어 국내의 조선소에서 많이 사용하고 잇는 용접 기법 중의 하나이다. $CO_2$ 편면 용접을 시공하기 위해서 가접보다는 strong back을 많이 사용하는데 strongback의 부착은 전 면과 후면에 부착시키는 2가지 경우가 있다. strongback을 전면에 부착할 경우 아아크는 strongback의 위치마다 중단된다. 후면에 부착할 경우 strongback으로 인한 아아크 중단은 없 어지나 용접사가 자세를 바꾸지 않고 한 번에 용접할 수 있는 최대 용접장은 1m정도이다. 이때 용접장 1m마다 아아크는 중단되게 된다. 이러한 아아크 중단부에는 용착 금속의 수축으로 인한 수축공(shrinkage hole)이 내재되어 용접 금속의 품질을 떨어뜨리므로 이를 제거하기 위해 용접 중 또는 용접 후에 gouging을 해야할 필요가 생긴다.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2003년도 추계학술대회
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• pp.285-290
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• 2003

This paper describes the NC simulator system for Wire-cut electrodischarge machining. Electrodischarge Wire-cut machining is applicable to all materials including metals, alloys, and most carbides. Although CAM system generate the NC code considering electrodischarge conditions, incorrect Wire-cut tool path bring about fatal results. The simplest way of simulating a EDM process is to display the trajectory of Wire-cutter location by line segments. With this kind of simulation, the programmer can get a general idea about whether the wire is moving as planned but cannot locate gouging or excess material because only the wire location will be seen, not the changes in the workpiece as it is machined. The ideal way of simulating the EDM process is to display the solid model of the workpiece as it is machined. Therefore we propose the ideal NC simulator system for Wire-cut EDM.