• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.541-545
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• 1996

In this paper, The performance and functions of automatic flatness control system installed on the 4 hi-reversing mill and has been investigated under actualconditions. A new automatic flatness control system incorporates a measuring roll for measurement and correction calculations, hydraulic roll benders, selective roll cooling, and a programmable controller for interface and data logging. The test results are as following. The more the exit steel strip thickness is thick, the smaller the I value, and the more it is thin, the larger the I value. And, a complex distribution of strip tension was controlled, for example, not only a quarter buckle but also a simple center wave and edge wave. Because the tension deviation is larger at acceleration speed and deceleration speed than steady speed, so automatic flatness control system of contact type is better to adopt over 450 m/min, automatic flatness control system reduces rapidly large flatness deviation. The maximum I value of strip has been decreased to 13 I, and defects caused by poor flatness have been drastically decreased. And coolant temperature for work roll cooling system on the automatic flatness control system is better to adopt about 50-55 .deg. C.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.27-36
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• 1999

To have high flatness quality of hot rolled strip in the hot strip finishing mill train, a new inter-stand tension profile measuring device of segmented looper roll type(coined as Flatness Sensing Inter-stand Looper, FlatSIL) and a new flatness control system have been developed in this study. The device measures the strip tension profile across the strip width and informs the strip wave pattern to new flatness control system where work roll bending mode to relieve the strip wave is determined. The existing automatic shape control system which uses laser type shape-meter installed at the outlet of the last finishing mill stand strip tension between down coiler and last finishig mill since the latent wave concealed by the strip tension between down coiler and last finishing mill stand cannot be measured by the laser distance-meter. Thus the existing shape control system is not able to control the flatness through the full strip length. The new flatness control system, however, works for full strip length during strip rolling as far as the tension profile measuring device and work roll bender are on. With the new flatness control system, work roll bender is automatically controller to minimize the latent wave of the running strip and the flatness quality as well as strip travelling stability has been noticeably improved from strip head through body to tail.

• Journal of Mechanical Science and Technology
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• v.18 no.3
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• pp.379-387
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• 2004

A novel flatness sensing system which is called the Flatness Sensing Inter-stand Looper(FlatSIL) system is suggested and a self-tuning PI control system using the FlatSIL is designed for improving the flatness of hot strip in finishing mill processes. The FlatSIL system measures the tension along the direction of the strip width by using segmented rolls, and the tension profile is approximated through the tension of each segmented roll. The flatness control system is operated by using the tension profile. The proposed flatness control system as far as the tension profile-measuring device works for the full strip length during the strip rolling in finishing mills. The generalized minimum variance self-tuning (GMV S-T) PI control method is applied to control the flatness of hot strip which has a design parameter as weighting factor for updating the PI gains. Optimizing the design parameter in the GMV S-T PI controller, the Robbins-Monro algorithm is used. It is shown by the computer simulation and experiment that the proposed GMV S-T PI flatness control system has better performance than the fixed PI flatness control system.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.27 no.1
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• pp.32-37
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• 2004

A new display device is required, which has concepts of flatness and slimness. FED can be one of the solutions. When we use flat panel, we can save the raw material and reduce the production time by eliminating the printing process, drying process, and washing process. In this case, good panel flatness and consistency with panel flatness and black matrix is the precondition. Therefor, we analyzed process capability of panel flatness and regression between panel flatness and BM position by experiments.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.3
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• pp.53-58
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• 2008

This study was conducted to evaluate the flatness of the porous type of dicing chuck. Two measurement systems for a vacuum chuck with a porous type of ceramic plate were prepared using a digital indicator and a laser interferometer. 6 inch of silicon and glass wafer were also used. Vacuum pressure from 100mmHg to 700mmHg by 100mmHg was increased. From experiments, chucked-wafer flatness was converged to the dicing chuck flatness itself even though the repeatability of contact method using indicator was unstable. Finally, the chuck flatness was estimated below $2{\mu}m$ with peak-to valley value.

• Journal of Industrial Technology
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• v.20 no.B
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• pp.27-34
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• 2000

The definition of flatness is given by ISO, ANSI, KS, etc. but those standards don't mention about the specific methods for the flatness. So various solution models that are based on the Minimum Zone Method have been proposed as an optimization problem for the minimax curve fitting. But it has been rare to compare some optimization algorithms to make a guideline for choosing better algorithms in this field. Hence this paper examined and compared Genetic Algorithm and Simplex Method to the evaluation of flatness. As a result, Genetic Algorithm gave the better or equal flatness than Simplex Method but it has the inefficiency caused from the large number of iteration. Therefore, in the future, another researches about alternative algorithms including Hybrid Genetic Algorithm should be achieved to improve the efficiency of Genetic Algorithm for the evaluation of flatness.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.9
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• pp.2901-2907
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• 1996

Flatness of cold rolled strip is vital to the quality of the product and productivity of the mill. Therefore, in recent year requirement for flatness control in strip rolling have become increasingly severe. The necessity for more accurate automatic gauge control and automatic flatness control(AFC) has increased by customer's requirement for cold rolled steel sheets with thinner gauge and better flatness quality. In this paper, the performance and functions of AFC system installed on the 4 hi-reversing mill has been investigated under actual conditions. The test results are as follows : The more strip thickness is thick, the smaller the I-value. The I-value is a strain measured by stressometer. Complex distributions of strip tension are controlled to remove not only a quarter buckle but also a simple center wave and edge wave. The defects caused by poor flatness have been drastically decreased. And a proper coolant temperature for work roll cooling system on the AFC system is about $50~55^{\circ}C$.

• Transactions of Materials Processing
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• v.14 no.1 s.73
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• pp.43-48
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• 2005

The production of metal strip with uniform thickness and flatness are two important problems associated thin strip rolling. The thickness and flatness of strip are affected by the flattening of contact surface between strip and roll, the elastic recovery and the bending of roll. Especially, the flatness of the strip is greatly affected by bending deflection of roll. The roll must be designed considered the elastic deformation of roll. This study describes the measurement of thickness and flatness of strip and shows the crown roll for producing flat strip. But it is difficult to produce the crown roller. The cross rolling that is a simple method which can produce the flat strip is introduced and it is found the optimal cross angle for improvement of flatness of plate. These problems are solved by the MARC code on the basis of elastic-plastic material and the updated Lagrangian formulation.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.66.5-66
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• 2002

Flatness of strip at aluminum cold rolling is one of the important quality parameters of rolled products. The reasons for this are perhaps obvious: for many of the end uses, subsequent processing requires a flat product poor flatness on-line can lead to reduced running speeds and hence to lower production levels. Amongst the reasons for lower running speeds is the increased risk of strip breaks. The Alcan Ulsan plant developed an automatic flatness control system on conventional four high mills for a year. This system compose of three parts as Intel RMX 3.3 operating system, advanced techniques, and flatness error analysis system. Strip flatness be measured by air bearing roll, passing the s...

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.551-555
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• 1996

The continuing demand for quality products requires better understanding and improved control of the production process. And, in recent year requirements for flatness control in strip rolling have become increasinglysevere because of the control for flatness of cold rolled strip is essential for further down stream processing. Also a speeds of rolling mills to meet productivity requirements puts a demanding requirement on the control of flatness of rolled strip. The demands on a total flatness control system therefore are a measuring and indication system consisting of a measuring roll that is robust, accurate, reliable and require a minimum of maintenance. The critical prt of any control system is the quality of the information being provided by the measurement instrument or device. It is therfore of utmost importance to have an accurate, repeatable and reliable measuring system. So, in this paper, The measuring roll for automatic flatness control system of contact type has been investigated.