• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 제3회 압연심포지엄 논문집 압연기술의 미래개척 (Exploitation of Future Rolling Technologies)
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• pp.180-187
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• 1999

This document illustrates the relationship between the wire rod wrinkle defect and the roll caliber design. The wrinkle defect is caused by the incongruent rolling conditions of the roll caliber design, the roll adjustment, and the extracting temperature. In this document, we restrict the study scope to the roll caliber design's effect on wrinkle defect at the base of real condition of the No.2 Wire Rod mill, POSCO. There has been wrinkle defect problem in the No.2 Wire Rod Mill, POSCO for many years. The engineers of the wire rod mill have been making efforts to solve the problem. As one of the efforts, we take the samples of the wire rod in the each stands of the 2'nd wire rod mill and then analyze the samples. Through the analysis, we find out the problem of the roll caliber design. So, we suggest the roll caliber design method to be more effective to weaken the wrinkle defect.

• 한국정밀공학회지
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• 제10권4호
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• pp.128-134
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• 1993

Work roll wear in the cold rolling of mild steel strip is strongly affected by rolling materials, rolling conditions and lubrication. The tests were performed to find the effects of rolling materials under the same lubrication conditions. The obtained results are as follfws; 1) The decrease in surface roughness of work roll is more rapid in that case of continuously cast A1-killed steel strip than ingot cast steel strip. In rolling of continuously cast A1-killed steel strip, worn powder rich in A1$\_$2/O$\_$3/sticks to the work roll surface, and so it makes the mirror surface of work roll accelerate. 2) Amount of work roll wear is small in rolling of continuously cast A1-killed strip. 3) In rolling of continously cast A1-killed steel strip, it is necessary to put up the intial surface roughness of work roll in order to prevent work roll slip.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.264-267
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• 2001

by three-dimensional finite element method. The guide roll is an intermediately supported trans-axle miler, so called I-STAR roll, which was designed by VAI. The guide roll has been used in POSCO since 1998. Though the number of stowage in casting has been apparently decreased since thef it has occasionally been failed during operation. The simulations were carried out to find out the status of stress and deformation as well as improvement of the guide roll. The thermal effect is much more dominant than ferro-static pressure or others in stress and deformation of the guide roll. The material of the guide roll is SCM440.

• 비파괴검사학회지
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• 제25권4호
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• pp.247-253
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• 2005

본 연구에서는 여러 굽 높이의 신발을 신고 보행하는 동안 발/발목 복합체의 roll-over 모양을 분석하였다. 본 연구를 위해서 근골격계 및 발 질환이 없는 15명의 건강한 성인 여성들을 대상으로 보행분석을 수행하였고, 실험에는 굽 높이가 다른 4종의 신발을 사용하였다. 보행분석 시 roll-over의 특성을 구하기 위해 초기접지기부터 반대발 초기접지기까지의 발목 및 무릎의 반사마커 궤적과 지면반발력의 압력중심 데이터를 이용하였다. 연구결과로 굽 높이가 증가할수록 roll-over의 모양은 원위방향으로 이동하고 그 특성은 굽 높이에 상관없이 일정한 형태로 관찰되었다. 또한, 6cm이하의 신발에서는 roll-over의 곡률중심이 수직방향으로 이동함으로써 일정한 roll-over 특성을 유지하도록 발/발목 복합체에서 자동으로 적응함을 알 수 있었다. 그러나 그 이상의 굽 높이의 신발에서는 발목관절만으로 충분한 균형을 보장할 수 없으므로 무릎 및 엉덩관절의 보상작용이 동시에 일어남을 알 수 있었다. Roll-over 특성에 대한 본 연구결과는 인간 보행의 보다 간단하고 넓은 이해를 제공할 것이고, 나아가 의지 또는 보조기와 같은 재활기기의 보다 넓은 이해를 제공할 수 있을 것으로 기대된다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.325-328
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• 1997

In this paper the modeling and control of a twin roll strip caster is investigated. Mathematical models for the strip casting process are obtained by analyzing five critical areas such that the molten steel level in the pool, solidification process, roll separating force and torque, roll dynamics including hydraulic actuators, and roll drive system. A two-level control strategy is proposed. At lower level, three local subsystems are independently feedback-controlled by suitable local controllers which perform well to the behaviors of each subsystem. They are a variable structure control of the molten steel level in the pool, an adaptive predictive control of the roll gap which is directly related to the strip thickness, and an $H^{\infty}$ control of the roll drive system. At higher level, all reference signals to the lower level subsystems are generated by an optimal controller in the perspective of regulating the strip thickness and roll separating force. Simulations are provided..

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 제5회 압연심포지엄 신 시장 개척을 위한 압연기술
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• pp.223-230
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• 2004

In order to improve the productivity and quality of the hot rolled products, many morden mills have continuously required advanced roll materials. The introduction of HSS rolls in early stands of the Hot Strip Mill brought the excellent performance in wear resistance and surface roughness. Ni-grain rolls used in the later stands was needed to improve the roll performance. Therefore, the carbide reinforced Ni-grain roll was developed. The present paper will describe the development of carbide reinforced rolls made by INI STEEL and the results of mill tests. The wear resistance was increased upto $40\%$ and the anti-accident ablility was remarkably improved compared to the normal Ni-rain roll.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.220-226
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• 1995

A study on the spalling causes of work roll for cold rolling was performed in the cold rolling mill. Performance of work roll is dependent to a great extent on spalling sothat both roll manufactures and users show great interest in spalling. So this paper shows that spalling origin on the roll surface. As being well known, spalling mostlyoccurred due to developing fatigue fracture originated a crack on a roll. But such spalling can be prevented by proper roll maintenance, The spalling accidents have sharply decreased since 1981 because of the use of ultrasonic test to detect cracks on a roll.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.323-324
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• 2006

This paper presents dynamics of register error on a compensator roll type converting machine. Though a register control is an important aspect of a converting machine, it has not been taken into account as a main subject. Lately, demands for high speed converting machines over 500mpm(m/min) are raising but domestic converting industries can not come up with the high speed machines because capacities fur designing of the converting machine is restricted lower than 300mpm. Moreover register control is the key to product flexible displays through roll-to-roll systems. In this paper, a compensator roll type register controller is analyzed using mathematical model of register error. A case study for reducing transient register errors is discussed.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.252-255
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• 2009

The roll gap set-up in the finishing mill is one of the most important technologies in the hot plate rolling process. As the target thickness can be obtained by the correct set-up of the roll gap, improving the roll gap set-up technology is very critical for plate thickness accuracy. The main cause of thickness variation in hot plate mills is the non-uniform temperature distribution along the length of the slab. The objective of this study is to adjust the roll gap set-up for the thickness accuracy of plate in hot rolling process considering top-end temperature drop. Therefore this study has concentrated on determining the correct amounts of roll gap to compensate thickness variation due to top-end temperature drop. The off-line simulation of compensated roil gap significantly decreases top-end thickness variation.

• 대한기계학회논문집A
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• 제30권10호
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• pp.1328-1334
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• 2006

In the rolling mills for sheet metal rolling, paper rolling and etc., the impurities of roller surface have crucial effects on the surface quality of the products obtained by rolling. The Roll Cleaner is a device to remove impurities on roller surface during a rolling operation. Nip Pressure means the line pressure interacted between the roll cleaner blade and the roller surface. The nip pressure is the most important parameter which decides the performance of roll cleaner, and it depends upon several factors including the cleaner design and its blade stiffness. This study, first, analyzes the mechanism of the nip pressure generation for a roll cleaner designed commercially, which is an crucial process for effective design of roll cleaners. Second, the technique for the measurement of nip pressure is developed, which is useful to verify the performance of roll cleaners and to setup them properly at factory floor.