• Journal of the Korean Society for Precision Engineering
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• v.7 no.3
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• pp.14-25
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• 1990

A model predicting thermal and wear crown in order to control strip crown and shape has been investigated at the hot roll mill. A basic equation of predicting wear crown was obtained experimentally whereas thermal crown was approximately analyzed by the integral method. The calculated result based on the accumulative model of basic eauation coincides with that measured under the real rolling conditions. The effect of wear corwn is also analyzed by the longitudinal feeding method of the work roll. The high frequency feeding method is recommended in removing local wear effectively.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.262-271
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• 1999

This work was intended to modify the solidification structure of high speed steel roll material for hot strip mill, by the introduction of alloying elements designed to form primary carbide dispersions via melt treatment procedure. Solidification structure was modified by the melt treatment with titanium and distribution. This modifying effect could be attributed to the fact that the nuclie formed at high temperature upon inoculation induce the formation of fine equiaxed grain and primary carbide during solification, which is also likely to be responsible for the fact that TiC acts as effective nuclie for primary VC solidification.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.4
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• pp.382-387
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• 2011

In this paper, a LBCC (Latter Bank Cooling Control) for the high strength steel is proposed to obtain the desirable temperature and the property of the material along the longitudinal direction of the steel on the ROT (Run-Out Table) process. A cooling valve is modeled to analyze the response of the ROT banks. The control concept is derived from a field data, a valve model considering the valve response and a TTT (Time-Temperature Transformation) diagram. The proposed control is verified from the simulation results under the various carbon quantities. It is shown through the field test of the hot strip mill that the deviation of the CT (Coiling Temperature) is considerably decreased by the proposed temperature control.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.75.5-75
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• 2001

In this paper, we study design of a ILQ(Inverse Linear Quadratic optimal control) looper control system for hot strip mills. The looper which is placed between stands plays an important role in controlling strip width by regulating strip tension variation generated from the velocity difference of main work rolls. A Looper servo controller is designed by ILQ control theory which is an inverse problem of LQ(Linear Quadratic optimal control) control. The mathematical model for looper system is obtained by Taylor´s linearization of nonlinear differential equations. Then we designed linear controller for linearization model by using the ILQ control algorithm. Thereafter this controller is applied to the nonlinear model for model identification. As a result, we show the controller´s robustness for the model error, external disturbance and sensor noise.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.249-252
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• 1997

Mini-mill process which is one of the new steel making process to be able to produce the hot rolled strip by thin slab caster, was completed in the kwangyang steel work. The new process was constructed liquid core deduction, tandem reduction unit, induction heater, coil box and finishing mill to be varied width. Therefore, in oder to make sure of target strip width, analysis of actual plant data was done to fine out amount of width deviation. Finally, the predication system of width in the mini-mill process was developed to included temperature caculation model.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.1
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• pp.34-41
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• 2016

Bar camber is a phenomenon in which a material with a deformation gradient across its width is bent in the right or left direction in the roll gap. This paper proposes a dynamic setup approach for a side guide for reducing bar camber. A bar tracking scheme using a rotary encoder was adopted to fix an operation point for the side guide. The guiding pressure was utilized for measuring the actual width of the bar with camber. Based on the accurate position and width of the bar, the side guide was dynamically set and operated at the actual roughing train in a hot strip rolling mill. The amount of camber was reduced notably when the dynamic setup scheme was installed in the side guide. 78% of the bars tested had a camber in the range of ${\pm}20mm$, which was an improvement of 27% in terms of production yield.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.1
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• pp.52-57
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• 2005

In the foe of global competition, the requirements for the continuously increasing productivity, flexibility and quality(dimensional accuracy, mechanical properties and surface properties) have imposed a mai or change on steel manufacturing industries. Indeed, one of the keys to achieve this goal is the automation of the steel-making process using AI(Artificial Intelligence) techniques. The automation of hot rolling process requires the developments of several mathematical models for simulation and quantitative description of the industrial operations involved. In this paper, an on-line training neural network for both long-term teaming and short-term teaming was developed in order to improve the prediction of rolling force in hot rolling mill. This analysis shows that the predicted rolling force is very closed to the actual rolling force, and the thickness error of the strip is considerably reduced.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.117-120
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• 2001

In hot roiling process, new rolling mills have been apapted to strip rolling but we can usually experience the problem of snaking of strip. This phenomenon was arisen by nonsymmetric rolling and on-centering and cambering of a strip and other mill conditions. Three dimensional analysis for strip rolling predicted the influence of nonsymmetric rolling, off-centering and pair crossing system This study evaluated the fundamental characteristics of snaking of a strip to optimize the operating condition for trouble free rolling.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.9
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• pp.869-874
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• 2015

We developed an LSDC (Load Shift and Load Distribution Control) technology in order to improve coil quality and productivity by reducing tension fluctuation especially for the tail of the strip in the down coiler in hot strip mills. To adapt the new controller, the torque and speed distribution between the zero pinch roll, pinch roll, and mandrel are needed. The proposed controller is a combination of an LSC to share the tension between the mill stand and the mandrel, and an LDC to shift the torque load from the zero pinch roll to the pinch roll. From the simulation, the proposed controller is verified under the torque disturbance. Using a field test, the torque deviation decreased by nearly 50% through utilization of the LSDC control.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.2
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• pp.191-196
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• 2008

This paper proposes a cooling stop temperature control(CSTC) concept which aims at obtaining the uniform temperature and quality of the material along the longitudinal and lateral direction of the strip. The CSTC is designed using the experimental CCT(Continuous Cooling Transformation), TTT(Time Temperature Transformation) curves and the temperature control model by the heat transfer governing equation, and the temperature control simulator. The cooling pattern and the rolling speed can be solved by the CSTC. It is shown through the field test of the hot strip mill of POSCO that the phase transformation ratio of the high carbon steel is considerably improved by the proposed temperature control.