• Title, Summary, Keyword: Flatness

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A Study on the Characteristics of Automatic Flatness Control System for Stell Sheet (강판의 자동 형상제어 장치의 특성에 관한 연구)

  • 김순경;전연찬;김중완;김문경
    • Proceedings of the Korean Society of Precision Engineering Conference
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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.

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Flatness Control System of the Hot Strip by Using Tension Profile between Stands (스탠드간 장력프로파일을 이용한 열연판 평탄도 제어시스템)

  • 홍완기;이준정
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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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.

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A Self-Tuning PI Control System Design for the Flatness of Hot Strip in Finishing Mill Processes

  • Park, Jeong-Ju;Hong, Wan-Kee;Kim, Jong-Shik
    • 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.

Comparison between Genetic Algorithm and Simplex Method in the Evaluation of Minimum Zone for Flatness (평면도의 최소 영역 평가에서 유전자 알고리듬과 심플렉스 방법의 비교)

  • Hyun, Chang-Hun;Shin, Snag-Choel
    • 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.

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A Study on the Flatness Evaluation Method of the Dicing Chuck using Chucked-wafer (웨이퍼 장착을 이용한 다이싱 척의 평탄도 평가 방법에 관한 연구)

  • Yook, In-Soo;Lee, Ho-Cheol
    • 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.

A Study on the Characteristics of Automatic Flatness Control System for Cold Rolling (냉각압연 가공용 자동 형상제어장치의 특성에 관한 연구)

  • Kim, Moon-Kyung;Jeon, Eon-Chan;Kim, Soon-Kyung
    • 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 $50~55^{\circ}C$.

Development of On-machine Flatness Measurement Method (평면도 기상 측정 방법 개발)

  • 장문주;홍성욱
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.3
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    • pp.187-193
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    • 2003
  • This paper presents an on-machine measurement method of flatness error fur surface machining processes. There are two kinds of on-machine measurement methods available to measure flatness errors in workpieces: i.e., surface scanning method and sensor scanning method. However, motion errors are often engaged in both methods. This paper proposes an idea to realize a measurement system of flatness errors and its rigorous application for estimation of motion errors of the positioning system. The measurement system is made by modifying the straightness measurement system, which consists of a laser, a CCD camera and processing system, a sensor head, and some optical units. The sensor head is composed of a retroreflector, a ball and ball socket, a linear motion guide unit and adjustable arms. The experimental .results show that the proposed method is useful to identify flatness errors of machined workpieces as well as motion errors of positioning systems.

A Study on Characteristics of Measuring Roll for Automatic Flatness Control (자동 형상제어용 측정롤의 특성에 관한 연구)

  • 김순경;전언찬;김중완;김문경;이승수
    • Proceedings of the Korean Society of Precision Engineering Conference
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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.

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A Study on Improvement of Flatness Control for Aluminum Cold Rolling Mill

  • Kim, Tae-Young;Bill Kraeling
    • 제어로봇시스템학회:학술대회논문집
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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...

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A Varactor-Tuned RF Tunable Bandpass Filter with Improved Passband Flatness

  • Kim, Byung-Wook;Yun, Du-Il;Yun, Sang-Won
    • Journal of electromagnetic engineering and science
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    • v.2 no.2
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    • pp.124-127
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    • 2002
  • A RF tunable bandpass filter using dielectric resonators and varactor diodes is redesigned to improve the passband flatness. Since the tunable liters are generally of narrow bandwidth and the Q value of the varactor diode is usually very low, the passband flatness is strongly deteriorated by sizeable distortion loss. To remedy this problem, we construct modified Chebyshev type filter by use of network synthesis techniques. The key of modified Chebyshev type filter is the rearrangement of the passband poles to improve the passband flatness. To maintain the constant passband bandwidth, design techniques of input/output stage and coupling windows are also applied. Experimental results show that the passband flatness can be improved by purposed method without any additional RF amplitude equalizer.