An Automatic Control Strategy of Strip Width in Cold Rolling

Transcription

1 Advanced Materials Research Subitted: ISSN: , Vols , pp Accepted: doi:0.4028/ Online: Trans Tech Publications, Switzerland An Autoatic Control Strategy of Strip Width in Cold Rolling Jilai Yu,a, Tingquan Gu 2,b, Jianguo Wang 3,c Baosteel-NSC autootive steel sheets co., ltd, Shanghai, China 2 Research Institute, Baoshan iron & steel co., ltd, Shanghai, China 3 School of Mechatronical Engineering and Autoation, Shanghai University, Shanghai Key Lab of Power Station Autoation Technology, Shanghai, China a yujl@baosteel.co, b gutq@baosteel.co, c jgwang@shu.edu.cn, Keywords: cold rolling; autoatic width control; width scalage; feed-forward control Abstract: This paper proposes an autoatic control strategy of the strip width in cold rolling process. The prediction odel for the exit strip width of each stand is established. In addition to the strip width variation of the incoing hot-rolled aterial between the easured and the pre-set values, the variations of the rolling force, tension, bending force and the roll shift aount of each stand are utilized to odel and forecast the stand exit width deforation. Then, the odel can be used to deterine the copensation values of the different profile adjustent echanis and the exit strip width can be controlled in high accuracy. In this way, the effect of the strip width variation of the incoing hot-rolled aterial and the fluctuation of the stand rolling process paraeters on the exit strip width can be eliinated. Moreover, the feed-forward control of the strip width can reduce the incidence of abnoral situation, such as the strip breakage and off-tracking, and iprove the stability of the cold rolling process. Introduction In addition to ensure the accuracy of the rolled strip thickness of steel rolling, the steel rolling also needs to ensure the accuracy of the strip width [].With custoers increasing yield requireent, the width precision is controlled up to the present 4~8 fro the past 20 [2]. Especially for the wide and narrow strip rolling ill, due to a considerable part of the finished product that will be used for spiral welded pipe and straight sea welded pipe, the width requireent is stricter. When reducing width deviation, yield can be increased by 0.% [3].Therefore, developing the new width control technologies can significantly benefit the producer [4]. The patent Jp A puts forward a strip width control ethod of the continuous annealing joint unit in cold rolling ills: Based on the difference between strip thickness detection value and set value. The last stand cold ill strip shape is used to control the strip width. The patent Jp A puts forward one cold rolling strip width control odel in the rolling speed change process: The functional relationship is established between each stand rolling force variation and plate-shaped echanis control variation, which are caused by the change of end stand exit strip width, the rolling speed and the tension between the stand variations. The ain objectives of the control ethod is to eliinate the cold rolling ill width variation without considering the tiely eliination of hot-rolled incoing width change and the ipact changes in width strip width of the rear stand caused by the upstrea strip width. Cold rolling width autoatic control In order to realize the width control, technical schee is as follows: ( Based on cold-rolled strip steel rolling theory and production practices, the change aount of iported hot-rolled strip steel in cold rolling ill, rolling force on each rack, tension, bending force and an roll axial channeling aount of variation act as the independent variables, the strip width variation of each rack outlet act as a function, and then the strip width of each rack outlet forecasting odels is established. All rights reserved. No part of contents of this paper ay be reproduced or transitted in any for or by any eans without the written perission of Trans Tech Publications, (# , Pennsylvania State University, University Park, USA-6/09/6,9:07:33

2 222 Advanced Materials and Technologies (2 Fig. shows that the strip width detector is placed in the entrance of cold rolling ill. The real-tie width detection of incoing hot-rolled strip steel in cold rolling ill is used to calculate the difference between the easured value and the width of the hot-rolled incoing settings. The difference is assigned in a certain percentage to each rack to eliinated strip width variation. (3The length and position of strip are real-tie tracked in the entrance of hot-rolled strip. When the position that the incoing hot-rolled strip steel are into a rack, the position aount of change of the incoing strip and the rack rolling variation of process paraeters are used to forecast export value of the rack width variation. Then, the export value is adjusted to zero to calculate real-tie copensation of rack plate-shaped bending force adjustent echanis and roll axial channeling aount. By ipleenting the above ethod, on the one hand, the incoing hot rolling rack width fluctuations and the ipact of various process paraeters on the end of the rolling rack outlet strip width are eliinated proptly. Then the control accuracy is iproved. On the other hand, the feed-forward width control of each rack can reduce the cross-section, deviation or other abnoral conditions and iprove the stability of the cold rolling production process. Fig. Strip width autoatic control function block diagra The following describes the specific technical realization and ipleentation: Cold-rolled plate rolling deforation theory shows that with the ill outlet strip width W is a function of the rolling process paraeters, conditions of entry and incoing paraeters of ill equipent. The strip width forecasting odel of the ill outlet is built as follows: W = W + ( K P + K T + K T + a 0 WiPi i WiT 0i 0i WiTi i i + ( K F + K F + K IMR WiFwi wi WiFi i WiIMRi i W the strip width of -stand ill outlet; P i, T 0i, T i respectively for the i th stand ill rolling process paraeters pressure, entrance tension, exit tension; the i th stand ill Work roll bending force F wi, interediate roll bending force F i and interediate roll shifting aount IMR i ; W 0 Incoing hot-rolled strip width; K WiPi, K WiT0i, K WiTi, K WiFwi, K WiFi, K WiIMRi respectively for the influence of strip width coefficient of exports to the i th stand ill, the i-th stand ill Rolling force, entrance tension, exit tension, work roll bending force, interediate roll bending force, interediate roll shifting aount; a i it is obtained by theoretical odels or experiental ethods. As rolling process of a coil, the thickness of the incoing hot rolled strip, echanical strength and ill paraeters such as roll size, shape and other basic raw roll reains unchanged and the a i ipact on export can be ignored. The new strip width forecasting odel of the ill outlet is built as follows: (

3 Advanced Materials Research Vols W = W + ( K P + K T + K T 0 WiPi i WiT 0i 0i WiTi i WiFwi wi WiFi i WiIMRi i W = W W 0 0 _ act 0_ set P = P P i i _ act i _ set T = T T 0i 0 i _ act 0 i _ set T = T T i i _ act i _ set F = F F wi wi _ act wi _ set F = F F i i _ act i _ set IMR = IMR IMR i i _ act i _ set Pi, T0i, Ti, Fwi, Fi, IMRi Respectively for the i-th stand ill Rolling pressure variation value, entrance tension of variation value, exit tension of variation value,work roll bending force of variation value, interediate roll bending force of variation value, interediate roll shifting aount of variation value; W0 hot rolled aterial width of variation value; W the i-th stand ill export strip width variation forecast values; W0_act hot rolled aterial width of the easured values; Pi_act, T0i_act, Ti_act, Fwi_act, Fi_act, IMRi_act respectively for the ith stand ill rolling force easured values, entrance tension of the easured value, exit tension of the easured value,work roll bending force of the easured value, interediate roll bending force of the easured value, interediate roll shifting aount of the easured value; Pi_set, T0i_set, Ti_set, Fwi_set, Fi_set, IMRi_set respectively for the ith stand ill rolling force setting value, entrance tension of setting value, exit tension of setting value,work roll bending force of setting value, interediate roll bending force of the setting value, interediate roll shifting aount of setting value. Forula (2 is used to calculate predicted width aount value Wi of -stand ill outlet strip. The forecasting strip width variation of the rack outlet can be 0 by changing the real-tie copensation value of shape and echanis adjustent in stand ill. That can proptly eliinate width fluctuations of the hot-rolled as well as the ipact of the end of the rack outlet strip width caused by each rack rolling process paraeters and iprove the stability of the cold rolling production process. Based on this basic idea of the control, the new autoatic strip width control is as follows: W + ( K P + K T + K T 0 WiPi i WiT 0i 0i WiTi i WiFwi wi WiFi i WiIMRi i (3 + ( K δ F + K δ F + K δ IMR = 0 WiFwi wi WiFi i WiIMRi i Fw, F, IMR copensation value, respectively belong to the -th stand ill flatness adjusting echanis of work roll bending force, interediate roll bending, interediate roll; The rest physical eanings of sybols are sae to equation (2. When incoing width change of the hot-rolled is large, if its ipact on exports by one strip width of the rack is copletely eliinated, the outlet plate-shaped ay have draatic changes and the stability of rolling process is not conducive to aintain. Hot-rolled incoing width W0 is allocated to each rack according to a certain proportion. Each rack eliinate the ipact on hot-rolled width strip caused by incoing width variation. The autoatic strip width control odel is as follows: (2

4 224 Advanced Materials and Technologies α W + ( K P + K T + K T 0 WiPi i WiT 0i 0i WiTi i WiFwi wi WiFi i WiIMRi i + ( K δ F + K δ F + K δ IMR = 0 j= WFw w WF WIMR n α =.0 j 0 α.0 j =, 2,, n j j is hot rolled aterial width variation in the distribution proportion coefficient of the -th stand ill,so it is with,n is cold rolling rack total unit. K WFw, K WF, K WIMR respectively for the influence of strip width coefficient of exports tothe -th stand ill, the -th stand ill work roll bending force, interediate roll bending force,interediate roll shifting aount; The rest physical eanings of sybol are sae to equation (3. δf w, δf, δimr has an infinite nuber of cobinations of the solution. According to the each plate-shaped response speed and the width different export efficiency. The priority coefficient of each individual plate-shaped adjusting echanis is given. The new autoatic strip width control odel is as follows: W ' = α W + ( K P + K T + K T 0 WiPi i WiT 0i 0i WiTi i δ F = β δ F = β δ IMR = β β + β + β =.0 WiFwi wi WiFi i WiIMRi i w Fw WFw F WF IMR WIMR Fw F IMR 0 β.0, 0 β.0, 0 β Fw F IMR W' strip width variation controlled by the -th stand ill; Fw, F, IMR the priority coefficient of copensation value, respectively belong to the -th stand ill flatness adjusting echanis of work roll bending force, interediate roll bending, interediate roll.the rest of the physical eaning of sybols are sae to equation (4. With six roller ill as an exaple, strip width autoatic control odel is established in this paper. For other rolling ill, you can follow the sae ethod to establish siilar odels. Straightness feed-forward control process diagra as shown in Fig.2. Siulation Result The present invention has been applied to a 420 five rack and six roller cold rolling ill,a steel width detector is installed in the entrance of the first one rack unit. Original tin plate has 2.5 entry thickness,050width and 0.24 exit thickness. Fig3 shows that strip width deviation curve in the fifth rack outlet when the autoatic width control ethods are not used, and the strip width control accuracy is about 2.0. Fig.4 shows that strip width deviation curve on in the fifth rack outlet when the autoatic width control ethods are used, and the strip width control accuracy is about.0. The coparison of Fig.3 and Fig.4 shows that the width accuracy is significantly iproved with use of the autoatic width control ethod.0 (4 (5. Fig.3. Strip width deviation curve adopting the proposed Fig.4 Strip width deviation curve not adopting the proposed ethod

5 Advanced Materials Research Vols Conclusion The strip width detector in the cold ill entry section easures real-tie the strip width of exit section, and the width is used to calculate the difference between the incoing width actual value and pre-set value, which is then assigned to each stand in a certain percentage to eliinate the incoing strip width variation. The effects of the strip width variation of the incoing hot-rolled aterial and the fluctuation of the stand rolling process paraeters on the exit strip width can be eliinated. The feed-forward control of strip width can reduce the incidence of abnoral situation, such as the strip breakage and off-tracking, and subsequently, iprove the stability of the cold rolling process. References [] Baohui Hou. Discussion on factors affected the accuracy of hot rolling steel strip width control [J], Metallurgical autoation, [2] Xinbo Li, Xiaoing, Mei-Gang. 422 strip width control is analysed[j], Meishan science and technology, 2008, (l : [3] Lv Cheng, Guodong Wang, Xianghua Liu. The width of strip finishing autoatic control [J].Iron and steel research, 997, 05: [4] Xianjun Cao. 2300Strip roughing autoatic width control research[d].northeastern university, 2009.