Roll Gap Crown Adjustment Characteristics of 1700 mm Cold Rolling Mills

The 4-hi cold mill is one of the key wide strip tandem cold rolling mills and has many advantages and characteristics. The mill type is the most important, fundamental and long-term effective factor for the strip shape control. Many advanced mill types such as CVC-4, HCW and PC-4, etc are created based on the conventional four-roll mill. The factors of mill type which affect the deformation of roll system, such as strip width, rolling force, bending force, work roll diameter, backup diameter and so on, arc studied how to affect roll gap crown. It provides a good foundation lbr improving the shape performance of mill.

Characteristics of unsteady lubrication film in metal-forming process with dynamic roll gap

Based on the theory of unsteady hydrodynamic lubrication and relevant mathematic and physical methods, a basic model was developed to analyze the unsteady lubrication film thickness, pressure stress and friction stress in the work zone in strip rolling. The distribution of pressure stress and friction stress in the work zone was obtained. A numerical simulation was made on a 1850 cold rolling mill. The influence of back tension stress and reduction on the distribution of pressure stress and friction stress between the roll gaps was qualitatively analyzed by numerical simulation. The calculated results indicate that the higher the back tension, the lower the pressure stress and the friction stress in the work zone, and the largest friction stresses are obtained at the inlet and outlet edges. The pressure and friction gradients are rather small at high back tension. The pressure-sensitive lubricant viscosity increases exponentially with the increase of pressure. The unsteady lubrication phenomenon in the roll bite is successfully demonstrated.

Identification and optimization for hydraulic roll gap control in strip rolling mill

In order to improve the control performance of strip rolling mill, theoretical model of the hydraulic gap control(HGC) system was established. HGC system offline identification scheme was designed for a tandem cold strip mill, the system model parameters were identified by ARX model, and the identified model was verified. Taking the offline identified parameters as the initial values, online identification using recursive least square was carried out with model parameters changing. For the purpose of improving system robustness and decreasing the sensitivity due to model errors, the HGC system based on generalized predictive control(GPC) was designed, and simulation experiments for traditional controller and GPC controller were conducted. The results show that both controllers acquire good control effect with model matching. When the model mismatches, for the traditional controller, the overshot will increase to 76.7% and the rising time will increase to 165.7 ms, which cannot be accepted by HGC system; for the GPC controller, the overshot is less than 8.5%, and the rising time is less than 26 ms in any case.

Roll gap prediction in acceleration and deceleration process of cold rolling based on a data-driven method

Severe fluctuation of the effective roll gap in the acceleration and deceleration section of the cold rolling process is a significant factor causing thickness deviation.However,the conventional roll gap compensation method and control strategy do not meet the stringent strip quality requirements.The roll gap model in the acceleration and deceleration process is studied to increase the thickness control precision.In order to improve model accuracy,a roll gap prediction method based on data-driven is proposed.Given the complexities of the cold rolling process,the extreme gradient boosting(XGBoost)method is used to predict the roll gap model as the rolling speed changes.Meanwhile,support vector regression and neural network-based methods are taken to evaluate and compare the prediction performances.Based on the field data,the simulation experiments are carried out.It demonstrated that the prediction performance of the proposed method outperformed the other two methods.The values of root mean square error,determination coefficient value,mean absolute percentage error and mean absolute error obtained from the XGBoost model were equal to 0.000346,0.952,7.02,and 0.00028,respectively.In addition,the proposed method analyzed the contribution rates of the rolling affecting parameters on the roll gap.The data showed that in the controllable rolling parameters,the rolling speed is the most impacting factor that disturbs the roll gap model in the acceleration and deceleration process,which can provide a useful direction for actual roll gap adjustment.

Analysis of Roll Gap Pressure in Sendzimir Mill by FEM

The acting force on the roll system of Sendzimir mill was analyzed using 3D FEM.The roll gap pressure distribution and the acting force between rolls S and O,rolls O and I,rolls O and J,rolls I and A,rolls I and B,as well as rolls J and B were analyzed.The results showed that the roll gap pressure mainly affected the roll surface layer,50 mm for backup roll;the roll gap pressure distribution is of double peaks among the work roll,the 1st intermediate roll（IMR）,and the 2nd IMR;the maximum value of the roll gap pressure between the backup roll and the second IMR appears on the edge of the barrel of rolls;the component force presents the in-para-curve distribution.These are important for reducing the wear of rolls and the break of the backup roll and guiding for production.

基于板带厚度误差PI反馈的轧机辊缝调节方法

针对轧机刚度系数未知波动影响板带厚度控制精度的问题,提出了基于板带厚度误差PI反馈的轧机辊缝调节方法。首先,建立轧机弹跳方程、液压辊缝调节动态方程,以及从辊缝设定值到板带出口厚度的动态方程;其次通过测厚仪和测压计,获取轧机出口处的板带厚度,以及轧机施加的轧制压力;然后设计基于板带厚度误差量PI反馈的辊缝大小的设定值,同时引入比例反馈增益系数与积分反馈增益系数的单参数化设计;最后将辊缝大小的设定值输入轧机液压辊缝调节系统进行辊缝调节,最终形成一套完整的轧机辊缝调节方法。该方法提高了轧制参数的预设定精度,大大减小了轧机刚度系数波动对板带厚度控制精度的影响,从而提高了板带厚度精度。

Numerical simulation of the temperature fields of stainless steel with different roller parameters during twin-roll strip casting

The temperature field of stainless steel during twin-roll strip casting was simulated by experiment and a finite element （FE） model. By comparing the measured result with the simulated values, it is found that they fit close to each other, which indicates this FE model is effective. Based on this model, the effects of roll gap （t） and roll radius （R） on solidification were simulated. The simulated results give the relationship between t or R and the position of the freezing point. The larger the t is and the smaller the R is, the closer the position of the freezing point is to the exit.

1180 MPa级超高强钢冷连轧过程的厚度综合控制技术

针对超高强钢在冷轧过程中厚度波动大以及带头带尾厚度超差的问题,首先根据金属秒流量模型建立了厚度超差预测模型与辊缝调节量预估模型;随后开发了轧制过程中的厚度控制系统,并进行了辊缝调节量优化;最后建立了带钢头尾轧制过程中的轧制速度与张力优化模型。以国内某冷连轧机组的第1机架为技术应用对象,选择两种典型的超高强钢进行生产测试,测试结果表明:超高强钢AR4146E1与DU6220A1的厚度超差长度分别从70.3 m、36.89 m下降到了16.85 m、16.33 m。

基于GAP单元的滚动轴承应力分析

利用有限元分析软件MSC.Marc/Mentat对某一滚动轴承进行有限元分析,采用GAP单元代替滚动体模拟轴承内外圈间的接触,在某组载荷工况下,计算该简化模型的应力结果;在同组工况下,对比实体轴承模型与GAP单元简化模型的有限元分析结果,对比各自的最大应力值;同时用理论计算方法计算轴承在相同工况下的最大应力值,来验证有限元结果的正确性。结果表明:GAP单元可以有效的模拟滚动轴承内外圈之间的接触,从而为滚动轴承建模及与轴承连接的组合件之间的建模提供了一种简便且有效的方法。

辊轴式残膜打包装置的设计与试验

【目的】针对国内现有残膜打包装置成捆机理不明确、作业时出现残膜逃逸、膜包杂质含量过高等问题,设计一种集残膜清杂及残膜打包为一体的辊轴式残膜打包装置。【方法】该装置主要由清杂输送机构、打包机构、传动系统等组成。通过理论分析建立清杂输送辊与残膜的力学关系,确定清杂输送辊的结构参数;根据清杂输送机构结构特征与作业原理,分析并确定清杂输送辊的布置间隙。采用机理分析方法分析残膜捆芯形成过程中残膜的受力与运动情况,并确定打包辊的运动参数。以成捆率和膜包含杂率为指标,机具前进速度、清杂输送机构倾斜角度、打包辊转速为试验因素进行正交试验,并对较优的参数组合进行田间验证试验。【结果】影响成捆率的主次因素依次为打包辊转速、清杂输送机构倾斜角度和机具前进速度;影响膜包含杂率的主次因素依次为清杂输送机构倾斜角度、机具前进速度和打包辊转速。以成捆率为主要指标,确定的较优作业参数组合为:清杂输送机构倾斜角度为10°、机具前进速度为1.5 m/s、打包辊转速为200 r/min。田间验证试验的膜包成捆率为98.1%、膜包含杂率为15.2%。【结论】该残膜打包装置满足田间作业要求,作业效果好,可为辊轴式残膜打包装置的设计与研究提供参考。

Accu Roll轧管机上导盘与左轧辊之间间隙的计算

根据空间解析几何的基本理论,推导了AccuRoll轧管机的上导盘与左轧辊之间间隙的计算公式,并结合某厂实际情况进行了计算分析,为解决该轧管机在生产实际中存在的产品内螺旋道,轧制速度不高,轧制薄壁管时导盘寿命低等问题,以及实现导盘和轧辊等工艺参数的优化设计和最佳调整提供了理论依据。

白象山选矿厂提高产能优化实践

白象山选矿厂为了进一步提高生产效率和产能,针对精矿产品质量、生产作业率等指标进行了生产流程优化,提高设备利用率,采用先进生产设备等研究。通过循环使用淘洗机尾矿溢流水,减轻了尾矿大井负荷,提高了磁选机的选别效果,同时优化湿式筛分预选工艺筛孔尺寸,提高了选厂处理能力;通过优化高压辊辊缝及频率等参数,使用新型侧挡板,延长了高压辊辊面的使用寿命,提高了设备利用率;通过使用凿岩台车、深孔钻机等智能采矿设备,改善了选厂给矿状况。现场生产实践表明,通过上述措施优化,有效提高了白象山选厂的产能。

板坯连铸机扇形段导向机构精细化设计

为了提高某钢厂板坯连铸机的使用寿命,提高生产稳定性和作业率及提升产品质量,对该板坯连铸机扇形段进行了重新设计。通过计算分析扇形段滑板间隙与锁死行程极限差以及辊缝偏差之间的影响规律,从而确定最优的板坯扇形段导向滑板方式和滑板间隙。研究表明:外侧滑板设置为长滑板、内侧滑板设置为短滑板优于外侧滑板设置为短滑板、内侧滑板设置为长滑板,不容易出现卡死现象;此外,辊缝偏差随着滑板间隙的增大而逐渐增大,但趋势逐渐减缓。计算分析后,上框架与侧框架之间的滑板间隙设计为0.5 mm,外侧滑板设置为长滑板,内侧滑板设置为短滑板,有利于提高扇形段运行稳定可靠性,改善连铸机生产作业效率。

Mechanical Properties of the Glue on Forward Roll Coating

The mechanical properties of the glue have great effects on the forward roll coating,which are analyzed here. The analysis shows that liquid viscosity,up and down rollers' speeds,diameters and the size of their gap have major impacts on coating property.The pressure and the shear force increase with the increases of the roll rotation speed,the radii and the viscosity of the glue,while decrease with the increase of the size of the roller gap. At a position of about 0. 8 mm from the nip symmetry axis by removing dimensionality,the pressure produces a maximum or minimum value,and the direction of the shear force changes.

核级包壳管轧制辊缝设定对尺寸和载荷的影响

由于核级包壳管需要在高温环境下长期承受高剂量的中子辐照及耐受冷却剂的强腐蚀,冷轧核级包壳管时对轧制过程以及轧辊进行合理的设计非常关键。为了能够轧制出符合尺寸精度要求的核级包壳管,采用变断面孔型轧辊的冷轧管机,根据冷轧机工作参数和孔型设计参数,计算得到规定生产工艺下的孔型。该孔型采用带直线侧壁的圆孔型,侧壁开口处采用切线过渡。采用有限元建模方法以及不同的边界条件对包壳管的轧制过程进行仿真,最后根据仿真结果分析冷轧过程中变断面孔型轧辊轧制核级包壳管的计算效果,通过控制辊缝跳动以稳定轧制成品精度和成形载荷。该研究为核级包壳管的实际生产、设备和工艺方案研发提供指导。

轧机辊缝清零原理研究及故障解析

冷连轧机辊缝清零是正常轧制和保障产品质量的前提。主要针对某1700酸轧轧机辊缝清零的原理及流程,对有带钢和无带钢两种清零模式PLC控制逻辑进行了详细解析。结合以往发生的典型案例,对辊缝清零常见故障进行了归纳总结。生产实践证明,对轧机辊缝清零过程以及常见故障进行研究,能够快速、有效地解决实际问题,为企业创造更高的经济效益。

冷轧机液压辊缝系统的优化控制研究

为提高板带材厚度精度,改善冷轧机电液伺服系统性能,将模糊自适应滑模控制技术应用于系统控制器设计中,选用合适的Lyapunov函数,三步算法就可实现对五阶系统的控制器设计,并在设计的最后一步同滑模控制技术结合;仿真结果说明,该控制器能够准确迅速跟踪指定位置,对于外界干扰、系统参数变化有很强的鲁棒性,且该控制器设计易于实现,可为工业应用提供有力支撑。

SWRCH22A盘条顶锻开裂机理研究与优化措施

近期某厂生产的6.5mm直径SWRCH22A冷镦盘条出现顶锻开裂现象,在此期间伴随着炸辊事故。对顶锻开裂的SWRCH22A冷镦盘条进行开裂机理研究发现,化学成分、金相组织、非金属夹杂物均符合要求,盘条径向两端的耳子是造成开裂的主要原因。通过调整辊缝、提高辊环冷却能力、调节固溶温度,改进后盘条合格率从提高近0.37%,炸辊事故也大幅度降低。

中宽带670 mm轧机极薄规格轧制与应用

为了扩大市场,满足客户以热代冷需求,某钢厂中宽带670轧机,从设计厚度1.8~7.5 mm,拓宽到最薄1.3 mm规格。依据现有设备,参照以往试轧的生产经验,进行优化,产品轧制方案分3个规格进行试轧,材质为GR50-11,规格分别为1.8 mm×380 mm、1.5 mm×393 mm和1.3 mm×410 mm。1.8 mm和1.5 mm规格轧制成功后,进行轧线设备能力估算,发现轧制材质为GR50-11、规格为1.3 mm×410 mm的带钢时,超出F6轧机设备能力,无法控制产品板型和精度。于是,材质更改为Q235B,再次轧制1.3 mm×410 mm规格,产品一次试轧成功。对下游客户进行走访,了解后期应用情况,客户反映可以满足以热代冷需求,达到客户使用要求。

特厚板坯窄边鼓肚原因分析与控制

特厚板坯在浇铸过程中由于窄边鼓肚变形引起液相穴富集溶质钢水流动,传热不均导致严重的中心偏析和中心线状裂纹,同时增加边角部裂纹发生率。因此特厚板坯窄边鼓肚已成为了限制其质量发展的重要因素。本文结合南钢特厚板坯连铸机实际生产工艺,在生产前通过进行扇形段辊缝调整、增强了结晶器与窄边足辊的冷却强度,增加了铸坯坯壳厚度;并通过增加结晶器窄边足辊对数,进行铸坯出结晶器后窄边锥度补偿,延长对铸坯窄边的支撑,减小了钢水静压力对窄边的作用力。通过加强对生产过程中间包钢水过热度与拉速的控制,在结晶器中形成较厚坯壳,有效解决了特厚板坯460/370 mm×(1800~2600)mm断面窄边鼓肚现象,窄边鼓肚单侧鼓肚量控制在5 mm以内,改善了特厚板坯的表面及内部质量。相关研究结果将为未来特厚板的品种研发提供理论基础。