• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 춘계학술발표회 논문집
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• pp.277-277
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• 2012

New concept of coating process, which is called Electro Magnetic Levitation-Physical Vapour deposition (EML-PVD) was developed and investigated. Zinc coating was performed and succeeded for the first time on the steel strip (Cold-rolled Steel) in a continuos pilot line using the EML-PVD process which is specialized in the high deposition rate and high vapor yield. EML-PVD will be expected to be the next generation coating technology to be applied to the steel industry.

• 한국정밀공학회지
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• 제13권5호
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• pp.67-73
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• 1996

The necessity for more accurate automatic flatness control(AFC) system has increased of customers' requirement for cold rolled steel sheet. Therefore, many cold rolling mills replaced its AFC system with a measuring roll of the contact type form the non-contact type. In this paper. The performance of AFC system of contact type has been investigated under industrial conditions. It has two kinds of actuator: roll bender, spot cooling system. The test results are as follows: The more strip thickness is thick, the smaller the I value, and the more it is thin, the bigger the I value. And a complex distribution of strip tension was controlled, for example, not only a pocket wave but also a simple center wave and edge wave. Because the tension deviation is larger at acceler- ation speed and decelerationspeed than steady speed, AFC system of contact type is better to adopt over 50m/mim. AFC system reduces rapidly large flatness deviation. The maximum I value of strip has been decreased to 13 I, and sticker, defects caused by poor flatness, have been decreased about 60%.

• 한국정밀공학회지
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• 제13권7호
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• pp.167-175
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• 1996

Work roll wear in the cold rolling of steel strip is strongly affected by rolling materials, rolling conditions and lubrication. Tests were performed to find the effects of rolling materials under the same lubricating conditions. Surface roughness of cold rolled steel strip as well as the coating technique itself is quite improtant in obtaining high image clarity of electronic products and car outer panels. Therefore this paper reviews for improvement of roughness and peak count about the surface of Cr coated work roll is investigated from the actual temper mill. The conclusions were obtained as follows; 1) Work roll wear in the cold rolling of steel strip is strongly affected by carbon contents of rolling materials, but there is not a separating force and total reduction ratio. 2) The roughness of strip surface is larger in the direction of width than in roll direction. 3) The electro-discharge textured roll has more uniform roughness distribu- tion than shot blasted roll and it's life time is two times longer than shot blasted because it has more harmonic wave roughness, and the higher peak count of surface roughness. 4) The life time of Cr coated work roll is 2 times longer than that of shot blasted work roll and variation of peak count, roughness and life time of Cr coated work roll is similar to electro-discharge texturing work roll. 5) The proper Cr coating thickness is 10 .mu. m at the work roll of temper mill.

• 한국재료학회지
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• 제31권10호
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• pp.576-581
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• 2021

To improve the shortcomings and expand the advantages of the single-roll melt drag method, which is a type of continuous strip casting method, the melt drag method with a molding belt is applied to AZ31 magnesium alloy. By attaching the forming belt to the melt drag method, the cooling condition of the thin plate is improved, making it possible to manufacture thin plates even at high roll speed of 100 m/min or more. In addition, it is very effective for continuous production of thin plates to suppress oxidation of the molten metal on the roll contact surface by selecting the protective gas. As a result of investigating the relationship between the contact time between the molten metal and the roll and the thickness of the sheet, it is possible to estimate the thickness of the sheet from the experimental conditions. The relationship between the thin plate thickness and the grain size is one in which the thinner the thin plate is, the faster the cooling rate of the thin plate is, resulting in finer grain size. The contact state between the molten metal and the roll greatly affects the grain size, and the minimum average grain size is 72 ㎛. The thin plate produced using this experimental equipment can be rolled, and the rolled sample has no large cracks. The tensile test results show a tensile strength of 303 MPa.

• 대한기계학회논문집A
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• 제22권4호
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• pp.723-730
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• 1998

With the introduction of edge drop control system in Tandem Cold Rolling Mill, it is necessary to develop te numerical expression for the set-up and edge drop automatic control of cold rolled sheet. As a first step we developed a simulation program which predicts profile and the amounts of edge drop at the delivery side of each stand by using roll deformation anlysis with the slit roll model. And by using the program the effect of various rolling conditions on edge drop was investigated. As a result the relations were obtained between the amounts of edge drop and rolling conditions. Based on above relations, the numerical expression was developed for the set-up and automatic control of edge drop by multi-regression of simulation results for the variation of edge drop amount with each rolling condition.

• 한국기계가공학회지
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• 제14권1호
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• pp.29-35
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• 2015

In this study, a FEM analysis is undertaken of a rubber sleeve which is mounted onto a spreading mandrel so as to avoid marking the first wrappings of coils (known as the 'end-mark'), as occasionally occurs when a concentrated load is placed on the edge of a steel sheet, significantly reducing its quality. A commercial numerical package, ANSYS, was utilized to analyze the structural behavior of the rubber sleeve. In general, the strain of the sleeve increases as the thickness of the rubber layer (H) covering the tubes increases, thus also increasing the surface of the sleeve for a constant boundary condition, and decreasing the pitch (P) between each tube, resulting in an increase in the strain on the surface of the sleeve for all rubber thickness conditions tested here. In a comparison of two different materials, rubber and urethane, when H=3 mm and P=1.1D, the maximum total deformations in these cases are 0.12669 mm and 0.086623 mm, respectively.

• 한국전자통신학회논문지
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• 제11권4호
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• pp.387-394
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• 2016

현재 운영되고 있는 제철소의 열연 공장은 24시간 상시 운전을 하고 있다. 각 공정별 주요 기능을 살펴보면 가열로, 조압연, 사상압연 및 권취 등으로 구성되어있으며, 여기에서 두께 및 폭 압연을 하고 이를 위한 소재의 온도를 조절하는데 큰 기능이 있다. 여기에는 작업의 특성상 고장 및 불량 요소가 상당히 많다. 또한 제품의 출하 이후에도 클레임이 발생하면 조사가 필요한 실정이다. 기존의 각 공정별 두께계, 폭계, 온도계에서의 독립적인 데이터 취득 및 모니터링에 의한 운전은 조업자로 하여금 많은 피로감을 준다. 이를 보완하고자 각 공정의 데이터를 통합해서 기능별로 모니터링하고 향후 작업 결과도 확인할 수 있는 통합 모니터링 시스템의 필요성이 대두되었다. 이에 압연공정 품질모니터링 시스템을 개발함으로서 보다 효율적인 운영이 가능하게 될 것으로 기대한다.

• 소성∙가공
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• 제8권1호
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• pp.65-77
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• 1999

In recent years, the quality requirements from the customers of hot rolled steel strip have been steadily increasing in diversity and strictness. To meet these quality requirements as well as to improve productivity, steel mills have been doing their efforts for developing high performance Automatic Gauge Control (AGC) system. However, it is very time consuming and also needs a lot of money to develop the new technologies of AGC in actual mill. So, there has been a demand for developing the Dynamic Hot Rolling Simulator since late 80's. It is a kind of software packages and can analyze the dynamic behaviors of hot finishing rolling process without laborious experiments in actual mill. It can also be used as a designing tool of Automatic Gauge Controller. In this work, the Dynamic Hot Rolling Simulator which is applicable to 6 sands hot strip mill rolling was developed. The MATLAB with SIMLINK was used as a software developer for making the main part of simulator because it is very powerful tool for modeling, integrating, controller design, and simulation. In this paper, the structures and the mathematical models of the simulator were briefly described and the results of simulation on the transient phenomena of hot rolling process with actual mill data were also presented.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.505-511
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• 1993

The results were obtained with changes according to the surface roughness of work roll and method to make the peak count on the roll in the temper rolling, and factors to affect to the work roll surface in actual rolling machine(ie. Temper mill). Conclusions are as follows. 1. E.D.T(Electro-discharge texturing)roll is more uniform roughness distribution than shot blasted roll and it's life time is two timees longer than that of shot blasted because it has more sine wave roughness. 2. The higher peak count of surface roughness, the more time is necessary to work roll texturing In shot blasting method, Surface roughness is relating to the grit size,impeller speed and hardness of roll material, But is can't control the peak count. 3. In shot blast texturing, Surface roughness of temper rolled strip which is transfered surface roughness of work roll is more ununiform than that of E.D.T roll 4. E.D.T roll has more uniform than the shot blasted roll and has more peak count than that of shot blasted roll. The surface of painted strip to image clarity is superior to that of shot blasted roll because E.D.T roll has more peak count and smooth surface.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.155-156
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• 2007

This paper presents the vision-based camber and optimal cutting line detection algorithm for hot-rolling process. It is important to measure the camber of head and tail part of strips because many problems are caused by the camber in the hot-rolling process. The hot-rolling process has time constraints. The camber detection algorithm of head and tail parts requires fast and less complex for satisfying time constraints. The proposed algorithm consists of two parts: measurement of the camber in the head and tail part of strips and decision part of the optimal cutting line of hot-rolled strip. First, we obtain the camber value of the strip from the difference between the real center line and the center line of head, tail part. Second, the head and tail part of strips isn't suitable for strips connections. Therefore, the cutting process is needed in the hot-rolling process. The optimal cutting line is determined by the head and tail images obtained from cameras. The algorithm is applied into the vision system with two area cameras, Matrox image processing board and host PC for verification.