• 한국정밀공학회지
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• 제22권3호
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• pp.137-145
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• 2005

The present research deals with structural analysis and optimal design of the heating drum of a hot-rolling press for medium density fiberboard. Stress concentration in the journal of the heating drum is analyzed by the submodel technique of the finite element method. The fatigue life under operating conditions is analyzed and evaluated by the stress-life theory. Shape optimal design problems, to minimize the maximum stress occurring in the journal, are formulated and shape parameters of the corner fillets of the journal are defined as the design variables. The problems are solved by the numerical optimization method and optimal shapes are found. The optimal designs are shown to be reliable in terms of the maximum stress and the fatigue life.

• 소성∙가공
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• 제7권2호
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• pp.150-157
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• 1998

Recently the SPPC technology is being developed in steel rolling industries for the purpose of enhancing mechanical properties of rolled sheets. The technology is to produce steel sheets with finer and more uniformly distributed grains by prediction of recrystallization behaviors and on-line control of rolling parameters during hot rolling process. In this study a finish rolling process was analyzed by a three-dimensional rigid-thermoviscoplastic finite element method and recrystallization behaviors of several locations in the sheet were predicted by Sellars equations. As a result it was found that the initial grain size of 84 ${\mu}m$ became $21-23\;{\mu}m\;20-22{\mu}m\;and\;18-20{\mu}m$ at front middle and end portions of the sheet respectively. It was also found that variations of the grain size became $$0.6{\sim}2{\mu}m\;and\;10{\mu}\mum$$ in thickness and width directions respectively.

• 한국소음진동공학회논문집
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• 제21권3호
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• pp.199-205
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• 2011

This paper proposes a framework to predict the mechanical fault of hot rolling mill system (HRMS). The optimum process of HRMS is usually identified by the rotating velocity of working roll. Therefore, observing the velocity of working roll is relevant to early know the HRMS condition. In this paper, we propose the framework which consists of two methods namely spectrum matrix which related to case-based fast Fourier transform(FFT) analysis, and three dimensional condition monitoring based on novel visualization. Validation of the proposed method has been conducted using vibration data acquired from HRMS by accelerometer sensors. The acquired data was also tested by developed software referred as hot rolling mill facility analysis module. The result is plausible and promising, and the developed software will be enhanced to be capable in prediction of remaining useful life of HRMS.

• Journal of Welding and Joining
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• 제8권2호
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• pp.70-79
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• 1990

Stainless clad steels were made through hot rolling process. Backing plates employed in this study were HSLA steel and mild steel. The shear bond strength increased with an increase of the soaking temperature and time. It was also found that the shear bond strength increased with an increase of the reduction ratio. The threshold deformation was observed to be 20% and 10% respectively when the soaking conditions of 15 min. at 900.deg. C and 30 min. at 1000.deg. C were applied. Either the rolling or the transverse direction did not give any significant difference in the shear bond strength. Stainless steel-HSLA steel was superior to stainless steel-mild steel in the same range of magnitude. Because the above experimental results were in contrary to the existing mechanisms, the new model was proposed to describe the bonding mechanism and the void formation.

• 한국정밀공학회지
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• 제13권2호
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• pp.48-61
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• 1996

In the hot strip mill, not only the chatter vibration of finishing stands has a great influence on the surface quality of hot products, but also that is the major factors to shorten the life of rolling mill housings or to create the machine troubles. As long as the mill has been operating, the low frequency chatter at the early mill stands (No.2 and No.3) of POSCO's Kwangyang No.2 hot strip mill had been detected when rolling certain types of products, e.g., thinner gage, hard grade products. For several years, the experimental study was undertaken to analyze the cause of the chatter vibration and establish the methods to avoid the vibration to acceptable levels. The analysis and solution to the vibration problem with recommendations and revised maintenance practice are the subjects of this article.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1993년도 춘계학술대회논문집; 한국과학연구소, 21 May 1993
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• pp.65-70
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• 1993

본 연구에서는, 제철 열간 압연기에서 slab가 진입, 추출시 충격으로 인한 진 동에 의해 두께 조절용 위치센서가 오작동을 하는 원인을 규명하고 그 해결 책을 제시하고자, 기존 AGC Top Plate와 위치 감지센서의 작동 상태 및 진 동특성을 검정하였고, 문제점을 발견하여 각각의 구조를 개선, 재측정하여 개선정도를 확인하였다. Disk형 AGC Top Plate는 직경을 줄이고, 두께를 늘 여 자체 진동을 감소시켜, Plate 진동에 의한 위치센서의 오작동 원인 및 이 에 의해 제어 유압펌프에 Feedback되어 top부 제어계에 발생하는 Hunting현 상을 줄였다. 위치센서는 내부 Spring의 초기변형량을 증가시켜 내탄성에너 지량을 증가시켜, 센서자체의 진동 및 측정시 나타나는 여진현상을 제거하였 다. 본 연구를 통한 측정결과로는 최대 82.7%의 제진효과와 여진현상의 제거 효과를 보았다.

• 한국생산제조학회지
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• 제20권6호
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• pp.817-823
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• 2011

This paper proposes a cooling stop temperature control(CST) and a phase transformation control(PTR) which aim at obtaining the uniform temperature and quality along the longitudinal direction of the high strength steel on the run-out table(ROT) process. The problems of the temperature control are analyzed for the conventional steel and the new control concepts are derived from a time-temperature transformation(TTT) diagram. The proposed control technologies are verified from the simulation results under the temperature prediction model by the heat transfer governing equation, and the temperature estimation simulator. It is shown through the field test of the hot strip mills that the phase transformation ratio of the high strength steel is considerably improved by the proposed temperature controls.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.538-543
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• 2008

A roller with a shaft and hot oil paths for pressing electrodes of polymer batteries were modeled and analyzed by FEM. There are many hot oil tubes in the roller and shaft, through which $72^{\circ}C$ hot oil flows for heating the surface of a roller and shaft. Thermal deformations and temperatures distributions of the roller and shaft were calculated and a convection boundary condition on surfaces was used. The influence of existence of a groove in the shaft on the flatness of a roller surface caused by thermal deformation was investigated. In addition, the amount of spring-back of electrodes under vacuum pressure and heating was calculated after the hot rolling process. It was shown from this study that the groove in one shaft had a favorable effect on the surface flatness.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.152-157
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• 2001

This paper presents the design method of the new controller for looper system in hot strip finishing mill. Looper response time is related to the performance of the tension control to reduce the delivery width error. The quality of the hot strip product, especially width deviation at the top of the strip, is influenced greatly by the precision of tension control. In this paper, a new fuzzy PID control system is designed to obtain the fast looper angle response and the high control precision. The computer simulation to verify the performance of the new controller is executed. From the results of the simulation, the tension control can obtain better performance than that of the conventional PID case.

• 대한기계학회논문집
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• 제16권8호
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• pp.1451-1457
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• 1992

본 연구에서는 작업롤의 온도분포를 정상 상태에서 롤의 길이 방향만을 고려 한 경우에 대하여 구한 다음 Fouries 급수로 전개하여 이 온도분포에 따른 작업롤의 축대칭 3차원 열-탄성문제를 해석함으로서 롤의 크라운 양과 열응력을 구하여 이 결과 를 유한요소법에 의한 결과와 비교 검토 하였다.