• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.322-325
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• 2002

We describe the looper controller design for a hot strip mill. The looper is to control the strip tension which influences on the width of the strip. It is very important to control the looper control of the hot strip mill, but difficult to control the looper, because there exists on mutual interaction among strip gauge, looper angle, and strip tension. In this paper, we present the modeling for the hot strip finishing mill to control the tension of the strip and suggest a cross control method. The cross control is a very simple method that allows non-interacting control.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.129.4-129
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• 2001

The looper control of hot strip finishing mill is one of the most important control item in hot strip rolling mill process. Loopers are placed between finishing mill stands and control the mass flow of the two stands. Another important action of the looper is to control the strip tension which influences on the width of the strip. So it is very important to control both the looper angle and the strip tension simultaneously but the looper angle and the strip tension are strongly interacted by each other. There are many control schemes such as conventional, non-interactive, LQ(Linear Quadratic), Hinf and ILQ(Inverse Linear Quadratic), Adaptive(gain scheduling) control in the looper control system. In this paper, we present the modeling for the looper of a hot strip finishing mill to control the tension of the strip and suggest another control method.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.67.1-67
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• 2002

We describe the looper controller design for a hot strip mill. The looper is to control the strip tension which influences on the width of the strip. It is very important to control the looper control of the hot strip mill, but difficult to control the looper, because there exists on mutual interaction among strip gauge, looper angle, and strip tension. In this paper, we present the modeling for the hot strip finishing mill to control the tension of the strip and suggest a cross control method of full-stand hot strip finishing mill. The cross control is a very simple method that allows non-interacting control.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2513-2515
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• 2000

The Hot Strip Mill(HSM) process consists of reheating furnace, roughing mill, finishing mill and coiler. Reheating furnace heats slab and roughing mill, finishing mill produces strip from this slab. The quality of this production mainly depends on finishing mill, which consists of 6 or 7 stands. Between stands a looper is installed for the better material flow. Automatic gage control(AGC), speed control system and looper system, which are connected with each other, are the main control systems for HSM. The low strip tension can make a loop between stands, which can be caused cobble. On the other hand, high strip tension causes thickness and width reduction, which affects the product quality, and can lead to tear the strip, if it is too high. Because of it, a proper strip tension is needed for better material flow: e.g. A good looper control system is substantial for the better production quality. What is handled in this paper is, the looper controller, which is developed to minimize the fluctuation of width of strip by maintaining an appropriate strip tension between stands and to achieve the stability of the looper control system. And its performance compared with a conventional PID controller is also discussed. The difficulties associated with the maintenance of the constant tension are described.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.13-16
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• 2000

In the hot strip mill, a bad threading and shape of strip strip in the finishing mill was caused by asymmetric rolling In roughing min. Mathematical analysis for camber control of roughing mill in hot strip rolling has been developed. Each equation in the camber control model was derived from geometrical characteristics of camber mechanism. The model can predict variables such as wedge, side slippage and roll force difference etc. from a measured camber value and then find an optimum roll gap condition for minimizing camber in the next pass.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.505-509
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• 2002

The looper control of hot strip finishing mill is one of the most important control item In hot strip rolling mill process. Loopers are placed between finishing mill stands and control the mass flow of the two stands. Another important action of the looper is to control the strip tension which influences on the width of the strip. So it is very important to control both the looper angle and the strip tension simultaneously but the looper angle and the strip tension are strongly interacted by each other. The gain scheduling is to break the control design process into two steps. First, one designs local linear controllers based on linerizations of the nonlinear system at several different operating conditions. Second, a global nonlinear controller for the nonlinear system is obtained by interpolating.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2267-2269
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• 2001

The looper control of hot strip finishing mill is one of the most important control item in hot strip rolling mill process. Loopers are placed between finishing mill stands and control the mass flow of the two stands. Another important action of the looper is to control the strip tension which influences on the width of the strip. So it is very important to control both the looper angle and the strip tension simultaneously but the looper angle and the strip tension are strongly interacted by each other. There are many control schemes such as conventional, non-interactive, LQ, LQG/LTR, and ILQ control in the looper control system. In this paper, we present the modeling for the looper of a hot strip finishing mill to control the tension of the strip and suggest the non-interactive(cross) and LQG/LTR control method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1854-1858
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• 2000

Chattering phenomenon is an abrupt relative vibration between the strip and rolls of rolling machine in working. It inevitably results from the progress of the degeneration in the mill facilities. This research was carried out in order to analyze the characteristic and find the cause of chatter mark in finishing mill and it was founded that one of major cause is appearance of dead zone at pinion stand in case of excessive roll force.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.68.6-68
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• 2001

There is a looper for the safety threading between stands in finishing mill. In this looper system, it is 2 inputs 2 outputs MIMO )Multi Input Multi Output) system, which has two inputs that are the angle of looper and the tension of Strip and has two outputs that are the torque of looper motor and the speed of Mill Motor. In tension controller of looper, it calculates the range of tension variation into the compensation value of speed and outputs to the speed controller of Mill Motor, so that it controls the tension of strip between stands. In this study, using this tension controller of looper, we adjust the establishment value of ...

• Journal of Mechanical Science and Technology
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• v.18 no.6
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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.