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금형가공센터 고속 이송체의 성능 안정화를 위한 설계개선 사례
최영휴,홍진현,최응영,이재윤,김태형,최원선 한국공작기계학회 2004 한국공작기계학회 춘계학술대회논문집 Vol.2004 No.-
Heavy-weight head slides may cause excessive inertia impact & moment on the machine tool structure when they move or stop abruptly during operation. Consequently these inertia impact and unbalanced moment bring transient vibrations and rough sliding motions on the machine structure. Machine tool engineers have tried many kind of feed-slide designs in order to solve this problem; for example, the design optimization of the moving structure for minimum weight and maximum stiffness, box-in-box type slide design, and so on. In this article, force and moment equilibrium equations regarding to the inertia force & moment were derived for each one of a mold M/C's head slides. Furthermore, five different design configurations of head slide assembly were reviewed for its design improvement regarding to force & moment calculations and finite element structural analysis results.
3차원 DOUBLE-TRACK 차량모델을 이용한 자동차의 주행거동해석
최영휴 國立 昌原大學校 産業技術硏究所 1994 産技硏論文集 Vol.8 No.-
The conventional 2-dimensional single track vehicle model has degrees of freedom related to only planar motions, and neglects the effects of suspension systems on vehicle manoeuvres. Whereas a 3-dimensional 12-degree-of-freedom vehicle model was proposed, in this study, to analyze handing and riding behaviors with taking into account the effects of nonlinear suspension and steering systems. The computed results of the proposed model are in good agreement with test results compared to the 2-dimensional model. Especially the proposed model showed the better accuracy near the characteristic speed and in high lateral accelerated manoeuvres.
가변 벌점함수 유전알고리즘을 이용한 금형가공센터 고속이송체 구조물의 최적설계
최영휴,차상민,김태형,박보선,최원선 한국공작기계학회 2003 한국공작기계학회 춘계학술대회논문집 Vol.2003 No.-
In this paper, a multi-step optimization using a G.A.(Genetic Algorithm) with variable penalty function is introduced to the structural design optimization of a high speed machining center. The design problem, in this case, is to find out the best cross-section shapes and dimensions of structural members which minimize the static compliance, the dynamic compliance, and the weight of the machine structure simultaneously. The first step is the cross-section shape optimization, in which only the section members are selected to survive whose cross-section area have above a critical value. The second step is a static design optimization, in which the static compliance and the weight of the machine structure are minimized under some dimensional constraints and deflection limits. The third step is a dynamic design optimization, where the dynamic compliance and the structure weight are minimized under the same constraints as those of the second step. The proposed design optimization method was successful applied to the machining center structural design optimization. As a result, static and dynamic compliances were reduced to 16% and 53% respectively from the initial design, while the weight of the structure are also reduced slightly.
다기능 5축 복합가공기 구조물의 저진동, 고강성 구조 최적설계
최영휴,김성민,장성현,황현영,정용민 한국공작기계학회 2007 한국공작기계학회 추계학술대회논문집 Vol.2007 No.-
This paper presents structural design optimization of a 5-axes multi-tasking machine for light weight and minimum compliance using genetic algorithm based 2-step optimization method. The design problem, in this study, is to determine thickness of structural members which minimize the static compliance, dynamic compliance and weight of the machine structure simultaneously under several constraints such as dimensional design constraints. Optimization results showed apparent reduction in static and dynamic compliances at the spindle nose of the machine in spite of reduction in machine weight.
불규칙 궤도외란을 받는 자기부상열차의 진동해석 및 2차현가장치 동적설계
최영휴,허신,김유일,Choe, Yeong-Hyu,Heo, Sin,Kim, Yu-Il 한국기계연구원 1992 硏究論文集 Vol.22 No.-
A dynamic design process was proposed for the design of the secondary suspension characteristics of a magnetically levitated vehicle(MAGLEV). It is based on a ride quality-secondary stroke trade-off. For the vertical vibration analysis, a magnetically levitated vehicle was simplified as 2 d.o.f. linear model, and FRA's class-6-track irregularities were considered as exciting disturbances. The optimum value of airspring stiffness and damping coefficient for the secondary suspension of a prototype MAGLEV was determined using this proposed design process.
Linear Motor 이송계의 진동 최소화를 위한 이송속도 최적화
최영휴,홍진현,최응영,김태형,최원선 한국공작기계학회 2004 한국공작기계학회 추계학술대회논문집 Vol.2004 No.-
Linear motor feed drive systems have been broadly used in machine tools or precision automatic feed systems. Recently, modern machine tools require high speed and high precision feed drive system to achieve high productivity. Unfortunately, a feed drive system, even though it was optimum designed, may experience severe transient vibrations during high-speed operation if its feed rate control is unsuitable. A rough feed rate curve having discontinuity in its acceleration profile causes a serious vibration problem in the feed slides system. This paper presents a feed rate optimization of a machine tool feed slide system, which is driven by a linear motor, for its minimum vibrations. Firstly, a 4-degree-of-freedom lumped parameter model is proposed for the vibration analysis of a linear motor driven machine tool feed drive system. Next, a feed rate optimization of the feed slide is carried out for minimum vibrations. The feed rate curve optimization strategy is to find out the most appropriate acceleration profile with jerk continuity. Of course, the optimized feed rate should approximate to the desired one as possible. A genetic algorithm with variable penalty function was used in this feed rate optimization.