• 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.

• 소성∙가공
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• 제32권3호
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• pp.114-121
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• 2023

During rolling, rolling mill rolls endure wear when shaping metal billets into a desired form, such as bars, plates, and shapes. Such wear affects the lifespan of the rolls and product quality. Therefore, in addition to rigidity, wear performance is a key factor influencing the performance of rolling mill rolls. Conventional methods such as casting and forging have been used to manufacture rolling mill rolls. However, powder alloying methods are increasingly being adopted to enhance wear resistance. These powder manufacturing methods include atomization, canning to shape the powder, hot isostatic pressing to combine the powder alloy with conventional metals, and various wear performance tests on rolls prepared with powder alloys. In this study, numerical simulations and experimental tests were used to develop and elucidate the wear analysis mechanism of rolling mill rolls. The wear characteristics of the rolls under various rolling conditions were analyzed. In addition, experimental tests (wear and surface analysis tests) and wear theory (Archard wear model) were used to evaluate wear. These tests were performed on two different materials in various powder states to evaluate the different aspects of wear resistance. In particular, this study identifies the factors influencing the wear behavior of rolling mill rolls and proposes an analytical approach based on the actual production of products. The developed wear analysis mechanism can serve the future development of rolls with high wear resistance using new materials. Moreover, it can be applied in the mechanical and wear performance testing of new products.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 제5회 압연심포지엄 신 시장 개척을 위한 압연기술
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• pp.349-358
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• 2004

The strip temperature history of finishing mill process is one of the most important factors to stabilize the facilities and to achieve the better product quality including a better prediction of roll force etc. The ultimate goal of this study is to improve scientific understanding of the finishing mill process in the view of heat transfer science. Finishing mill cooling facilities of KwangYang $\#3$ hot rolling are introduced and heat transfer analyses from FET to FDT are particularly focused in this study Three major tasks are successfully achieved as follows: 1) The temperature Prediction Models are developed. 2) The average absolute error is found to be less then 10 Celsius degree (about $8.5^{\circ}C$). 3) Prediction rate (less then $\bar{+}20$) are $10.2\%$ improved $(80.1\;\rightarrow\;90.3\%)$.

• 한국지능시스템학회논문지
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• 제11권4호
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• pp.315-319
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• 2001

회전체 베어링 상태진단에 신뢰성을 갖기 위하여 여러 가지 진단 방법이 연구되고 있으며, 이때 이용하는 변수는 온도와 소음, 진동 그리고 윤활유가 있으며 분석 방법으로는 온도추이분석, 소음분석, 진동분석, 윤활제 분석방법이 주로 이용되고 있다. 본 연구에서는 압연기 베어링의 상태진단 변수로 베어링의 진동 신호를 선택하고 이 진동신호에서 비선형성이 강한 신호 즉 카오스적 거동이 있음을 정성적인 방법으로 타켄스의 매립법에 의한 상태공간 재구성과 포엔카레 단면, FFT, 히스토그램을 이용하고, 정량적인 방법으로 프랙탈 차원, 리아프노프 지수를 이용하여 확인하였다.

• 대한기계학회논문집A
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• 제27권2호
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• pp.327-333
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• 2003

Most of shape defects in steel strip are originated from the structure of rolling mill itself. For instance, strip crown occurs when the work roll is deformed by the bending moment induced on roll chocks. To get rids of the shape defects, it is necessary to increase the stiffness of rolling mill. The structure change of back-up roll is one of alternative ways to increase the mill stiffness without facility revamping from 4 high mill to 6 high mill. In this research work, the new back-up roll was developed and can be used in any type of 4 high mill to reduce the strip shape defects. The developed back-up roll consists of sleeve, arbor and phase angle adjusting system for arbor. The circumference of arbor is specially machined to adapt the strip width change during rolling. The experimental cold rolling test was done to prove the effectiveness of newly developed back-up roll. The experimental rolling results show that the new back-up roll has more powerful performance in reducing the shape defects than conventional back-up roll. It was also found that the new back-up roll has higher stability for shape control. In addition to, the only sleeve surface needs to be reground and changed in most cases, so that the maintenance cost can be greatly reduced.

• 소성∙가공
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• 제12권7호
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• pp.668-674
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• 2003

Rigid-plastic finite element analyses on the deformation of slabs at various width reductions have been performed. By using commercial finite element code, dog-bone profile, crop profile and the longitudinal width profile after edging and Horizontal rolling have been analysed. The deformation behavior of slab for the heavy edger mill has also been compared with that for the sizing press. From the deformation analyses, it was found that the sizing press-horizontal rolling method is more efficient in width reduction than that of heavy edger mill-horizontal rolling. The results of finite element analyses fer the deformation of slab were well confirmed by the actual operational data. It was found that the amount of width variation after sizing and rolling is about 5∼10mm.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 제3회 압연심포지엄 논문집 압연기술의 미래개척 (Exploitation of Future Rolling Technologies)
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• pp.429-437
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• 1999

Width variation of the top and bottom ends of steel at finishing rolling in a plate, has been investigated. It was found that width variation after finishing rolling is affected by edging, broadside rolling ratio, longitudinal rolling ratio, width shape after broadside rolling, temperature, width-to-thickness ratio, and so on. A neural network modelling of back propagation has been conducted on the width variation during rolling. Based on these prediction models, a width control system, by which the roll opening and closing of the hydraulic AWC edger can be adjusted during edge rolling in finishing rolling passes, has been developed. Compared to conventional width model, the neural network model is much accurate in a model. The width control system is applied to a newly built production mill.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.39-39
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• 2000

In this paper, a decoupler of tandem cold rolling mill is designed. Before designing the decoupler, this paper improved conventional linear model by considering friction and yield stress of rolling strip. In a stand, the decoupler let an output be controlled by an input. And even if states of other stands should be changed, current stand takes no interference from those changes. In addition, with the same method, a feedforward controller is designed for an input strip thickness error. Finally, performance of controllers above is shown with nonlinear simulation.

• Journal of Mechanical Science and Technology
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• 제18권6호
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• pp.972-978
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• 2004

Forward slip is an important parameter often used in rolling-speed control models for tandem hot strip rolling mills. In a hot strip mill, on-line measurement of strip speed is inherently very difficult. Therefore, for the set-up of the finishing mill, a forward slip model is used to calculate the strip speed from roll circumferential velocity at each mill stand. Due to its complexity, most previous researches have used semi-empirical methods in determining values for the forward slip. Although these investigations may be useful in process design and control, they do not have a theoretical basis. In the present study, a better forward slip model has been developed, which provides for a better set-up and more precise control of the mill. Factors such as neutral point, friction coefficient, width spread, shape of deformation zone in the roll bite are incorporated into the model. Implementation of the new forward slip model for the control of a 7-stand hot strip tandem rolling mill shows significant improvement in roll speed set-up accuracy.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 제3회 압연심포지엄 논문집 압연기술의 미래개척 (Exploitation of Future Rolling Technologies)
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• pp.47-56
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• 1999

New rolling speed prediction model has been developed for the precise presetting rolling speed of each finishing mill stand in the tandem hot strip mill. Those factors such as neutral point, work roll diameter, rolling torque, friction coefficient, bite angle and the thickness at each side of entry and deliver of the rolls were taken into account. To consider width effect on forward slip, calibration factors obtained from rolling torque has been added to new prediction model and refining method has also been developed to reduce the speed unbalance between adjacent stands. The application of the new model showed a good agreement in rolling speeds between the predictions and the actual measurements, and the standard deviation of prediction error has also been significantly reduced.