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고속 주축의 진동 특성 향상을 위한 베어링의 위치 선정
임정숙(J. S. Lim),황영국(Y. K. Hwang),이원창(W. C. Lee),이춘만(C. M. Lee),정원지(W. J. Chung) 한국정밀공학회 2005 한국정밀공학회 학술발표대회 논문집 Vol.2005 No.10월
This paper presents analysis of dynamic characteristics of a high-speed milling spindle with a built-in motor. The spindle system with a built-in motor can be used to simplify the structure of machine tools, to improve the machining flexibility of machine tools, and to perform the high speed machining. In this system the shaft is usually assumed as a rigid rotor. In the spindle system design, it is very important to improve modal characteristics, and modal analysis is performed in the first place. Therefore in this paper, on the assumption that supporting bearings of spindle was selected most suitable condition, analyzed dynamic characteristics of a high-speed spindle according to its position. Optimal design was applicated to select most suitable position of bearings. Considered the mass and stiffness effects of the built-in motor"s rotor are analyzed by numerical method. The result shows the natural frequency of 1st bending mode of spindle.
임정숙(J. S. Lim),송용현(Y. H. Song),이영선(Y. S. Lee),문영훈(Y. H. Moon) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.10
Tube bulging process is a relatively complex manufacturing process because of this process depends on the part shape, kind of materials, boundary conditions and etc. Due to this complex manufacturing process, optimization parameters of tube bulging process has been investigated using finite element method analysis. In this paper, optimized bulging pressure curve is proposed which to bulge complex shape such as a head-tube of bicycle frame. Simulation is performed with commercial FE analysis program FORGE<SUP>®</SUP> and the result compared with the experiment result. It was found that the experiment and simulation results were in good agreement.
임정숙(J. S. Lim),천세환(S. H. Chun),문영훈(Y. H. Moon),이영선(Y. S. Lee) 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.5
Steel tube has been used widely in many fields, such as in the power, transportation and chemical industries and so on. Therefore, most of the time, their mechanical properties are strictly required in detail. In order to enable those parts to work within the safety limits a large variety of heat treatments are conducted in precedent studies. Especially, to produce bended pipe, many process and simulation technique has been developed. Bending applying local induction heating is an efficient way to produce bended pipes of various radius with lower cost and to provide better quality product, since it was invented by Dai-ichi High Frequency Co.(DHF) of Japan in 1961. And it is very important to simulate bending process with transient and residual stresses in surface hardening by high frequency induction heating, to predict the process result. In this paper, to verify confidence of bended pipe, FEM simulation was conducted and compared with the residual stress using hole-drilling gage method.
임정숙(J. S. Lim),이영선(Y. S. Lee),문호근(H. G. Moon),문영훈(Y. H. Moom) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.5
By hot compression test in the temperature range of 800-1100℃ and the strain rate range of 0.01-10 s?¹, hot deformation behavior of Ti-6Al-4V was characterized. And processing maps including flow stability criteria and Ziegler’s stability criterion were generated using the compression test data. In order to evaluate the reliability of the map, the microstructure characteristics of the hot compressed specimens were correlated with test conditions in the stable and unstable regime. The microstructure and processing map of Ti-6Al-4V was applied to predict an optimum condition and unstable regions for hot forming processes.
임정숙(J. S. Lim),이영선(Y. S. Lee),문호근(H. G. Moon),문영훈(Y. H. Moon) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.5
Radial forging is a unique process used for forging of round and tubular components. This operation has been used extensively in both hot and cold forging operations. Since radial forging operations have certain specific advantages as compared to other alternatives, process improvement is required. And this process is often compared to open die forging. Therefore, in this paper, mechanical properties of STD11 forged bar manufactured by both open die forging process and radial forging process were compared.