Effect of Deformation between Stands on the Strip Shape in Hot Rolling

A theoretical model about the secondary deformation is developed by the combination of analytical and experimental approaches. A system simulation based on the model is completed to predict the strip profile after the interstand deformation. On the other hand, comprehensive experiments and quantitative comparisons are made to calibrate the model for a wide variety of products. As a result, the correction of the model has been verified by the actual rolling data from production mill and it is helpful to improve the strip shape control.

Strip shape control capability of hot wide strip rolling mills

The elasticity deformation of rolls was analyzed by means of two-dimensional finite element method （FEM） with variable thickness. Three typical mills were used as objects for analysis. A thorough study was done on the control capabilities of these mills on the strip shape. Then the strip shape control capabilities of the three mills was compared synthetically. 2008 University of Science and Technology Beijing. All rights reserved.

Development of the entire roller inlayed block intelligence cold strip shape meter and its industrial application

The entire roller inlayed block intelligence cold strip shape meter is developed successfully in this paper,which can stably work chronically in the cold rolling workshop,the independent innovation of the key technology of cold strip shape measuring,the foreign technical monopoly and blockade are broken through.The structural form which is different from the international popular segmented detection roller is put forward,the entire detection roller inlayed block is developed,a group of elastic blocks in that the sense organs are installed are inlayed in the radial symmetry rectangular grooves of the detection roller body,the entire roller structure is composed of elastic pieces and the roller body,the scratch of the strip surface due to different thermal expansion of the traditional detection roller measuring unit is avoided effectively.The signal transmission form which is different form the international popular dry slip ring is put forward,the spray wet slip ring is developed,slip ring and detection roller can be taken down and installed as possibly as fast,so the maintain is convenient,while through the section auto-spray cleaning,lubrication and cooling, the service life is remarkable improved and the outside interference signal is reduced.The signal processing form which is different form the international popular gathering card is put forward,the embedded DSP shape signal processing hardware system is developed,the electromagnet,temperature,humidity and vibration's interference of industry practice to shape transmission signal can be effectively avoided,which can guarantee the instantaneity and measured precision of shape measured signal.The shape signal processing software system whose function contains error compensation,pattern recognition,establishment of the target shape and the closed-loop control calculation is built,the shape meter' computer human interaction is friendly,and function of shape meter is strong,at the same time the intellectualized level of the shape meter is improved.Now,this shape meter has been successfully applied on the 1 250 mm cold strip mill of Angang Steel Company Limited,the long-term operating testing is done,every guide line achieves the anticipative effect,the measuring precision is high and the measuring signal is stable and reliable,the shape meter is tested on high speed,big tension,changed wrap angle and big depressed complicated working conditions,any scratch of the detection roller surface and the strip surface is not appearing,it can completely adapt well to the industrial production environment,reaching the international advanced level.

Optimization of pass schedule to improve the strip shape in hot strip rolling

In this study,the authors proposed a new algorism which can simultaneously meets the strip shape control criterion and the strip crown control criterion.Based on the new algorism,the pass schedule is optimized to maximize the allowable PC angle range.To calculate the objective value for optimization of pass schedule,a slab method has been integrated with the roll stack deformation to simulate the strip profile.

Control Strategies of Asymmetric Strip Shape in Six-High Cold Rolling Mill

It is a complicated problem for cold-rolled strip to improve asymmetric strip shape in strip production. A roll system and strip coupled model of six-high cold rolling mill was established with finite element method to estimate the effect of intermediate roll shifting, tilting, symmetric and asymmetric bending technologies on strip profile. To reduce asymmetric defects of strip shape as much as possible, some control strategies were proposed, including tilting and asymmetric bending of intermediate roll and work roll. The combinations of these three control strategies can effectively eliminate asymmetric strip shape defects. Finally, the closed-loop control model of asymmetric flat- ness at the last stand was given, and the flatness control system with the function of asymmetric strip shape control was also designed for cold tandem mill.

Development and Experimental Evaluation of Strip Shape Prediction Model for Sendzimir Rolling Mills

It is difficult to obtain the desired strip shape using Sendzimir rolling mills because small diameter work rolls can be easily deformed by the roiling force. To control the strip shape effectively, it is important to understand the relationship between the behavior of the shape actuator and the variation of the strip shape. A numerical model based on the contact element method was proposed for the prediction of strip shape. In this numerical model, the re- lationships between the actuating forces, the roll deflections, the thickness profiles of the entry and exit sides, and the strip shape were considered. The proposed numerical model for strip shape prediction was evaluated by computer simulation and experiment with respect to various AS-U roll and first intermediate roll positions.

Improvement on strip flatness of cold temper mills by modifying roll contour shape

A study on roll gap profile (strip profile) control was accomplished in a1700 mm single-stand temper mill. Some critical problems such as the deviation of work roll contourcaused by grinding and wear, the effectiveness of work roll bending were discussed. Using a finiteelement model, the effects of roll contours (ground and wear) on strip profile were investigated.The roll bending effect on strip thickness was also analyzed. It is pointed out that there are somespecial features of flatness control in the temper mill: during temper rolling, roll deformation isslight due to small rolling load, and the loaded roll gap profile mainly depends on work rollcontour, while the backup roll has a little effect on gap crown; the effect of bending force ongauge can not be ignored due to the coupling between flatness control and gauge control. A new rollcontour arrangement adaptable to the mill was presented and has been put into practical production.The application of the new set of rolls showed some good results: larger crown control range of workroll bender, higher rolling stability, better strip profile and flatness quality.

Influence of lateral displacement on strip shape during cold rolling

The theory of metal plastic deformation is an important part of the strip shape control theories. In order to control the shape and gauge accurately during cold thin strip rolling, the mechanism of the metal lateral flow must be revealed clearly. Therefore, the lateral displacement of thin strip was studied by the grid method. Those grids with a line thickness of 10 μm and clear boundaries were successfully manufactured on the strip surface using lithography. Then, the effects of reduction, front and back tension, and taper angle of the first intermediate roll on the metal lateral flow were studied. The strip shape was calculated with and without considering the lateral displacement; furthermore, the calculations were compared with the measured results. The results show that the calculations with considering the lateral displacement are closer to the measured results. In addition, the comparison of finite element analysis results with the experimental results indicates that the test method was reliable.

Research and Development Trend of Shape Control for Cold Rolling Strip

Shape is an important quality index of cold rolling strip. Up to now, many problems in the shape control domain have not been solved satisfactorily, and a review on the research progress in the shape control domain can help to seek new breakthrough directions. In the past 10 years, researches and applications of shape control models, shape control means, shape detection technology, and shape con- trol system have achieved significant progress. In the aspect of shape control models, the researches in the past improve the accuracy, speed and robustness of the models. The intelligentization of shape control models should be strengthened in the future. In the aspect of the shape control means, the researches in the past focus on the roll opti- mization, mill type selection, process optimization, local strip shape control, edge drop control, and so on. In the future, more attention should be paid to the coordination control of both strip shape and other quality indexes, and the refinement of control objective should be strengthened. In the aspects of shape detection technology and shape control system, some new types of shape detection meters and shape control systems are developed and have successfully indus- trial applications. In the future, the standardization of shape detection technology and shape control system should be promoted to solve the problem of compatibility. In general,the four expected development trends of shape control for cold roiling strip in the future are intelligentization, coordi- nation, refinement, and standardization. The proposed research provides new breakthrough directions for improv- ing shape quality.

Shape Setup System for 1700 Hot Strip Mill

Shape setup （SSU） system is the core technology for hot strip mill （HSM）. A precise SSU system was used to improve the strip quality for HSM. The function of SSU, setup, and feedback was introduced. The main mathematical models of roll gap profile and longitudinal strain difference are set up. Strip profile allocation strategy was researched according to the SSU system of a domestic 1 700 mm HSM. The SSU system was put into practical use and the measurement results showed that strip flatness variation and strip profile variation could be controlled in target scope.

Industrial shape detecting system of cold rolling strip

A high-precision shape detecting system of cold rolling strip is developed to meet industrial application,which mainly consists of the shape detecting roller,the collecting ring,the digital signal processing(DSP) shape signal processing board and the shape control model.Based on the shape detecting principle,the shape detecting roller is designed with a new integral structure for improving the precision of shape detecting and avoiding scratching strip surface.Based on the DSP technology,the DSP shape signal processing circuit board is designed and embedded in the shape detecting system for the reliability and stability of shape signal processing.The shape detecting system was successfully used in Angang 1 250 mm HC 6-high reversible cold rolling mill.The precision of shape detecting is 0.2 I and the shape deviation is controlled within 6 I after the close loop shape control is input.

Novel Impact Absorption Device Using NiTi Shape Memory Alloy Strips

The aim is to propose and design a kind of novel impact absorption devices using constant-force elements made from Ni Ti shape memory alloy( SMA) strips for safety protection.The availability evaluation results indicate that the constant-force elements can absorb over one half of the impact energy for its martensite transformation and thus the maximum impact force is reduced by nearly 80%.Compared with the ordinary cylindrical compression spring,the device's maximum impact force is reduced by nearly 50%,otherwise it has a very compact structure and insensitivity to the varying impact,and thus it is especially suitable for narrow space and safety purpose.

TORSIONAL IMPACT RESPONSE OF A PENNY-SHAPED CRACK IN A FUNCTIONAL GRADED STRIP

The torsional impact response of a penny-shaped crack in a nonhomogeneous strip is considered. The shear modulus is assumed to be functionally graded such that the mathematics is tractable. Laplace and Hankel transforms were used to reduce the problem to solving a Fredholm integral equation. The crack tip stress field is obtained by considering the asymptotic behavior of Bessel function. Explicit expressions of both the dynamic stress intensity factor and the energy density factor were derived.And it is shown that, as crack driving force, they are equivalent for the present crack problem. Investigated are the effects of material nonhomogeneity and (strip's) highness on the dynamic fracture behavior. Numerical results reveal that the peak of the dynamic stress intensity factor can be suppressed by increasing the nonhomogeneity parameter of the shear modulus, and that the dynamic behavior varies little with the adjusting of the strip's highness.

Comprehensive contour prediction model of work rolls in hot wide strip mill

The predictive calculation of comprehensive contour of work rolls in the on-line strip shape control model during hot rolling consists of two important parts of wear contour calculation and thermal contour calculation, which have a direct influence on the ac- curacy of shape control. A statistical wear model and a finite difference thermal contour model of work rolls were described. The comprehensive contour is the equivalence treatment of the sum of grinding, wear, and thermal contours. This comprehensive contour calculation model has been applied successfully in the real on-line strip shape control model. Its high precision has been proved through the large amounts of actual roll profile measurements and theoretical analyses. The hit rates （percent of shape index satisfying re- quirement） of crown and head flatness of the strips rolled, by using the shape control model, which includes the comprehensive contour calculation model, have about 16% and 10% increase respectively, compared to those of strips rolled by using manual operation.

Off-line Simulation of PFC for Hot Rolling Strip

In order to improve the quality of the strip for the hot continuous rolling, the high accuracy set-up control must be applied to production. In the paper, we analyze the RFC (profile and flatness control) system and simulate the set-up process. Calculation results are in agreement to the actual measurements. It is the basis on the developing model.

柳钢1450热轧线粗轧板形控制方法探究

柳钢1450热连轧生产线精轧工序头尾穿带稳定性极大程度受到粗轧中间坯板形影响,偶尔发生因来料板形差引发的楔形大、轧破、甩尾等现象。特此结合粗轧区域设备特性探索粗轧板形控制方法,对关键设备采取针对性改进措施,如设备对中精度、压下系统精度、装备配合间隙等,并开发投用板形调整功能适配工艺参数优化,应用于实际生产并取得明显效果。

基于改进斑点鬣狗算法的热轧带钢负荷分配智能优化

针对热连轧过程中由于负荷分配不均匀导致板形控制效果不佳的问题,以传统的轧制机理为基础建立负荷分配均匀、板形良好的目标函数,分别采用斑点鬣狗算法和改进斑点鬣狗算法进行单目标和双目标的负荷分配的优化求解。结果表明,改进斑点鬣狗算法将末机架的相对凸度差从0.000 834 5降低到0.000 014 83和-0.000 026 34,且在允许的范围内,上游机架负荷分配合理,充分发挥了轧机的轧制能力。

基于锻轧成形工艺的KFC异型铜带组织性能研究

研究了KFC热轧合金带坯在锻轧工艺制备异型铜带过程中,通过冷锻、在线退火和轧制等工艺处理后内部组织的演变规律,并采用金相显微镜、电导率测试仪、维氏硬度仪及拉伸试验等检测了产品的综合性能指标。结果表明,带坯在冷锻加工率为69.45%时,带材薄料区域处晶粒不断细化,内部产生大量位错带,加工硬化作用显著,带材的强度、硬度增大。对锻轧材料进行固溶退火处理后,晶粒不断加粗,且部分FeCu_(4)固溶物质转变为Fe相的Cu相。经过锻轧复合加工,材料的总形变量为74.79%,其抗拉强度和硬度由热轧态的289 MPa和65.3HV提升至336 MPa和112HV,电导率由85.12%IACS提升至89.23%,折弯次数在5次以上,展现出优异的综合性能。

复杂地形隧道防水板及施工缝施工技术优化

穿越复杂地形地貌的铁路隧道的防水板、施工缝等施工处理,一直是业内关注的技术难点。本文依托山西中南部铁路太行山隧道项目,分析了工程所在地质情况及可能发生的病害问题,介绍了工程中采用的防水设计,并根据工程实际需求提出了防水板焊接工艺、防水板固定间距、控裂技术、梯形背贴式止水带技术等系列优化措施。该系列优化技术应用于工程收到了良好效果。

隧道二衬中埋式止水带安装工艺的改进及新型加劲止水带的应用

高铁隧道二衬施工时可能在材料种类及数量、施工工艺选用等因素影响下出现埋设位置不够精准、中埋式止水带线型不一等问题。郑万高铁黄家沟隧道工程,纵向止水带采用U型托夹配合支杆定位、张拉,环向止水带采用T型筋精准定位;为更好的保证工作效果,采用了新型加劲止水带。工程实践表明所采取措施有效提升了中埋式止水带设置深度、结构平顺度及位置准确度,防水效果提升而工期缩短、经济效益良好。