Effect of Rolling Parameters on Plate Curvature during Snake Rolling

In order to predict the plate curvature during snake rolling, FE model was constructed based on plane strain assumption. The accuracy of the FE model was verified by the comparison between the plate curvature conducted by FE model and experiment respectively. By using FE model, the effect of offset distance, speed ratio, reduction, roll radius and initial plate thickness on the plate curvature during snake rolling was investigated. The experimental results show that, a proper offsetting distance can efficiently decrease plate curvature, however an excessive offsetting distance will increase plate curvature. A larger speed ratio, reduction will cause a large plate curvature, however a larger roll radius has effect to reduce plate curvature. Plate which undergoes a larger reduction and plate with a larger initial thickness always need a larger offset distance to keep the plate the minimum plate curvature, but for a larger roll radius a smaller offset distance is needed.

Analysis of strain variation in cross shear zone of plate during snake hot rolling

In order to study the distribution of equivalent and shear strain of aluminum alloy plate during snake hot rolling, several coupled thermo-mechanical finite element models(FEM) are established. Effects of speed ratio and offset distance on strain distribution of the plate are analyzed. The length of cross shear zone is defined to have a better understanding of the deformation characteristic in cross shear zone, which is the essential difference from symmetrical rolling in deformation zone. The results show that the equivalent strain and shear strain of lower part both increase with the increase of speed ratio, while the upper part decreases; the equivalent strain through the whole thickness decreases with ascending offset distance, while the shear strain of lower part increases. The length of cross shear zone quickly increases with ascending speed ratio and slightly decreases with ascending offset distance. The "positive" and "negative" cross shear zones are formed with the increase of speed ratio and offset distance, respectively. The value of the sensitivity coefficient of speed ratio is an order of magnitude bigger than the offset distance. However, the shear strain at center point increases with the ascending speed ratio and offset distance for different mechanism. As speed ratio increases, the asymmetry of the distribution of equivalent is becoming larger and the shear strain is generated in the same direction in cross shear zone. The FEM results agree well with experimental results.

超大型环件径轴向轧制过程偏移机理及自适应模糊控制方法研究

超大型环件径轴向轧制过程容易产生偏移,影响环件轧制稳定性和成形质量。为研究环件偏移机理及其控制方法,分析了轴向孔型滑移区中前滑区和后滑区的分布变化规律,建立了理想情况下不产生环件偏移时锥辊旋转运动学条件,获得了滑移区的最优速度匹配系数。此外,从历史轧制数据中归纳人工控制经验后提出了基于锥辊转速自适应模糊调节的环心偏移量控制方法,基于ABAQUS软件和VUAMP子程序开发,建立了集成有环心偏移量模糊控制算法的∅10 m超大型环件径轴向轧制有限元模型,研究了采用最优速度匹配系数的常规控制和自适应模糊控制下的环心偏移量变化规律。结果表明,自适应模糊控制下的平均环心偏移量相比于常规控制降低了72.4%,仿真结果和试验数据均验证了所提超大型环件轧制过程偏移自适应模糊控制方法的有效性。

Bending analysis and control of rolled plate during snake hot rolling

In order to study the bending behavior of aluminum alloy 7050 thick plate during snake hot rolling, several coupled thermo-mechanical finite element(FE) models were established. Effects of different initial thicknesses, pass reductions, speed ratios and offset distances on the bending value of the plate were analyzed. ‘Quasi smooth plate' and optimum offset distance were defined and quasi smooth plate could be acquired by adjusting offset distance, and then bending control equation was fitted. The results show that bending value of the plate as well as the extent of the increase grows with the increase of pass reduction and decrease of initial thickness; the bending value firstly increases and then keeps steady with the ascending speed ratio; the bending value can be reduced by enlarging the offset distance. The optimum offset distance varies for different rolling parameters and it is augmented with the increase of pass reduction and speed ratio and the decrease of initial thickness. A proper offset distance for different rolling parameters can be calculated by the bending control equation and this equation can be a guidance to acquire a quasi smooth plate. The FEM results agree well with experimental results.

Accu Roll轧管机导盘偏心距的调整

Ａｃｃｕ Ｒｏｌｌ轧管机采用三维可调的大直径主动旋转大导盘， 以增大对轧件的纵向拉力， 利于轧件金属在孔型中的流动，限制其宽展， 增大轧件的延伸。通过对 Ａｃｃｕ Ｒｏｌｌ轧管机轧辊、导盘速度匹配关系的分析， 对导盘偏心距的调整进行了理论探讨， 提出了相应的调整措施。

Research on Mechanical Model and Properties of New-type Negative Offset Structure in Spatial Seven-bar Heavy Shear

According to revised Cailikefu’s rolling shear force formula,motion path equation of spatial seven-bar path is built,and mechanical model,with such new structural features as negative offset,is thus successfully established for 2 800 mm heavy shear of some Iron&Steel Company. Shear force and bar force of steel plate,before and after adoption of negative offset structure,are analyzed,as well as horizontal force component of mechanism that influences pure rolling shear and back-wall push force that keeps blade clearance. The discovery is that back-wall push force could be kept large enough at rolling start-up (i.e. the time that the maximum rolling shear produces),meanwhile,back-wall push force is the most approximate to side forces with adoption of 60 mm-100 mm offset. Theoretical results and on-site shear quality both indicate that new structural features such as negative offset plays an important role in ensuring pure rolling shear and keeping blade clearance constant,which provide an effective means to improve quality of steel plate.

Mechanical Properties of New Type Negative Offset Structure During Shearing Process of Heavy Steel Plate

According to the revised Cailikefu＇s rolling shear force formula, motion path equation of spatial seven-bar path was built, and a mechanical model, with the new structural feature of negative offset, was thus successfully established for 2 800 mm heavy shear of some iron and steel company. Shear and bar forces of steel plate, before and after the adoption of negative offset structure, were analyzed, as well as horizontal force component of mechanism that influences pure rolling shear and back-wall push force that keeps blade clearance. It was found that the back-wall push force keeps large even at the time that the maximum rolling shear was obtained; meanwhile, back-wall push force is the most approximate to side forces when 60--100 mm of offset was adopted. Both theoretical results and onsite shear quality show that the negative offset plays an important role in ensuring the stability of pure rolling shear and keeping blade clearance constant.

摇摆工况下错位瓦轴承支撑的转子系统动力学特性

基于轴承刚度和阻尼的分段线性化假设,建立了不同横摇角度的转子轴承模型;利用DLAP软件,耦合求解错位瓦轴承支撑的转子系统的动力学模型;采用特征值和特征向量、不平衡响应分析、稳定性分析和瞬态动力学分析等手段,研究了轴系的稳定性和安全性,并与正常工况下轴系的动力学特性对比,得到了摇摆工况下错位瓦轴承支撑的转子系统的动力学特性。

中板轧制过程板坯弯曲生成与抑制之五──轧制线高度及轧辊偏移距对板坯弯曲的影响

研究了在中板轧制过程中抑制板坯弯曲的措施之一．从理论上剖析了轧制线高度和 轧辊偏移量大小与板坯弯曲的关系，给出了实用的轧制线高度的确定原则．实践已证明合理的 轧制线高度是一种抑制板坯弯曲很有效的措施．

超限车侧滚振动偏移量的确定方法及影响因素分析

建立计算超限车侧滚振动偏移量的数学模型，分析各种因素对侧滚振动偏移量的影响，并通过实例验证了模型的可靠性。

平面拟合法校正多波束换能器横向安装偏差

针对多波束测深系统换能器横向安装偏差校正不完善的问题,提出了一种以近似平面估算换能器横向安装偏差的方法。分析了横向安装偏差对海底地形测量的影响,采用选权迭代的方式对子区平坦海底进行平面拟合,以平面拟合系数求解模型作为计算平面方程的推值模型,利用两近似平面夹角确定换能器横向安装偏差,将计算结果带入CARIS软件船配置文件中,完成对换能器横向安装偏差的二次校正。实验结果表明,该法能有效探测换能器横向安装偏差,且经二次校正后的主检测线交叉区域水深值具有较好一致性,满足海道测量规范要求。

胶印机串墨辊轴向速度的分析

从理论上分析了胶印机中串墨辊的轴向速度分布,利用计算机仿真证明了理论计算的结论,确定了胶印机中串墨辊在不同的起始位置启动的时候轴向的速度不同,导致了胶印机启动时轴向的不同冲击。

六辊冷轧机辊间压力分布的模型研究

分析了六辊冷轧单机架在存在偏移量条件下的辊系受力情况,并应用影响函数法对其进行计算。计算结果表明,其与不带有偏移量的辊间压力分布基本相同。因此在计算辊间压力分布时,可以用不带有偏移量的模型来代替。

超限货物列车与邻线普通货物列车会车条件

采用SIMPACK多刚体系统动力学仿真软件建立N17AK型平车的超限重车动力学模型,仿真计算不同工况下超限货车侧滚振动引起的横向偏移量,依据仿真计算结果给出超限货物列车与邻线普通货物列车在超限货物不同高度处的会车条件。仿真计算表明,在线路工况相同的条件下,侧滚振动引起的货车横向偏移量随着超限货物列车运行速度的提高而增大;在线路工况和超限货物列车运行速度均相同的条件下,侧滚振动引起的货车横向偏移量随着超限货物计算点距轨面高度的增加而增大;超限货物列车以120 km.h-1的最高速度在Ⅰ级线路上运行和以70 km.h-1的最高速度在Ⅲ级线路上运行这2种不利工况相比较,以后者的侧滚振动引起的货车横向偏移量为大。

热连轧机水平振动仿真与实验研究

某热连轧机在轧制薄规格板材时发生强烈振动,为确定其振动类型和振源,对其进行仿真计算和测试分析。首先计算该轧机水平振动和主传动系统的固有频率和主振型;然后对该轧机主传动系统和辊系振动情况进行综合测试,发现该轧机水平振动最剧烈,并引起轧机垂直振动和主传动系统扭振,因此,对该轧机水平振动进行仿真分析,研究轧件厚度以及工作辊和支承辊偏移量对水平振动的影响。研究结果表明:轧件厚度越薄,后张力和轧制力的波动越大,对轧辊水平振动影响增大;工作辊与支承辊偏移量的增大,轧机水平振动降低,达到稳态振动的时间缩短,但该偏移量不宜过大。增加0.7 mm厚垫片减小工作辊水平振动的方案,可以减小间隙,明显抑制轧机水平振动,效果良好。

双机架四辊可逆冷轧机组辊系稳定性分析

轧制过程中辊系的稳定性影响轧辊轴承和轴承座等部件的使用寿命以及轧件质量。设置合理的工作辊偏移距,可保证轧机辊系在负载状态下满足稳定性的力学约束。针对双机架可逆冷轧机组,轧件要在两台轧机上往复进行多道次轧制,且两机架前、后张力设定策略不同的情况,结合现场实际轧制规程,分析了采用不同轧辊偏移方向时轧机辊系的受力状态,确定了保证辊系稳定的工作辊偏移距。研究结果可为双机架可逆冷轧机组辊系稳定性提供有益参考。

现代冷带轧机偏移距和微跑偏机理

现代冷带轧机的偏移距设置源于保证轧机辊系稳定性的力学约束 ,靠轧机辊系在负载状态下作用于轧辊的水平力来实现。偏移距与水平力 (稳定性 )成某种比例 ,在专业教科书及参考书中都有详细的介绍并给出计算方法。然而 ,其力学约束在轧制动态过程中不稳定而失效 ,偏移距便失去设置意义却留下较大的水平力后患 ,引起一系列“随机”事故 ,困扰轧制生产。另外 ,在轧机负载时由轧机支承辊、轴承座、机架及连接挡板组成的辊系产生“轧制线微跑偏”现象 ,对其危害至今没有被人们所认识 ,因而未能对症解决相关的事故。偏移距设置和轧制线微跑偏皆属轧机在负载状态下辊系的微尺度(轧辊弹性变形和轴承座 -机架运动副间隙 )行为 。

蛇形热轧中轧制参数对7075铝合金厚板变形分布的影响(英文)

介绍了蛇形轧制的实现方式。运用数值模拟方法,在Deform 3D上分析单道次轧制过程中蛇形轧制和对称轧制7075铝合金厚板的流动速度及应力应变分布情况,分析异速比、上下轧辊错位量和压下量对蛇形轧制变形区内轧板等效应变和剪切应变的影响规律。结果表明:蛇形轧制中,由于下辊速度快,轧板下层金属流动比上层快,蛇形轧制中轧板下层等效变形大于上层,且随着异速比的增大,上下层金属变形差距增大;对称轧制中厚板心部的剪切应变几乎为0,蛇形轧制中由于有"搓轧区"的存在,厚板心部的剪切应变远大于对称轧制的,且随着异速比的增加和错位量的增加,轧板心部的剪切变形增大。这种附加的剪切变形有利于使变形向厚板心部渗透,从而改善厚板高向变形的不均匀性。

利用塑性5ε_t与中性层偏移的二辊矫直辊型设计方法

为了提高棒材二辊矫直机的矫直精度,依据棒材矫直工艺特点和矫直辊磨损区域分析,提出了"凹三凸二"的矫直辊组合形式及辊型设计方法。在辊型设计过程中,根据棒材矫直的实际变形规律,提出了塑性5εt矫直应力应变拟合原则,更加准确地描述了棒材矫直变形的应力应变关系;结合微元法对矫直棒材内部金属的受力状态及中性层偏移进行分析,推导出了含有硬化系数与中性层偏移的新弯矩比公式。在此基础上,通过对矫直力与辊面磨损关系以及残余应力和弹性芯对隐患挠度影响的综合分析,精确给出了矫直不同规格棒材时辊腰段的反弯曲率比范围,从而能最大限度地降低辊面磨损,克服因残余应力回复而导致矫直质量不稳定的缺陷。基于上述理论和方法,给出了具体设计实例,并对矫直过程进行了数值模拟分析,给出了矫直过程中影响棒材矫后精度的各参量状态。结果表明:设计辊型的残余直线度为0.64mm/m,隐患挠度为0.202 4mm/m,预测弹复后直线度小于0.85mm/m,从而显著提高了棒材的矫后精度及其稳定性,同时也验证了该设计理论与方法的正确性及有效性。

四辊轧机辊系偏移距机理的不确定性和微尺度静定性

生产板带的四辊轧机辊系,普遍设置偏移距求得轧辊间平行定位及其稳定以防止辊间交叉,成为四辊轧机辊系平行定位机理编入轧机教科书及参考书中。近代相继出现的现代四辊轧机辊系都设置偏移距,但未能保证其机理的确定性,辊间动态交叉现象的发生屡禁不止,引发超大轴向力损坏推力滚动轴承或生成轧制支反力偏差破坏板形控制的稳定性。设置偏移距3mm的高速铝箔四辊轧机轴向力在线检测试验,揭示轧制过程中工作辊与支承辊之间发生规律性动态交叉现象。轧制中轧辊之间的动态交叉行为,与轴承座和机架窗口立柱间微小间隙大小相对应,只限于轧机的交叉角β≤0.05°区间,远小于交叉(Paircross,PC)轧机的交叉角(β=1°～1.5°),但派生的轴向力超出额定值的3倍以上。四辊轧机模拟辊系偏移距静态零调试验,探明轧辊间初始安装位置不变没有轧辊的水平位移。辊间动态交叉现象和静态水平位移为零的两种结果,揭示出设置偏移距机理的不确定性,不能用于四辊轧机辊系平行定位及稳定性设计。