四辊轧机叼板窜辊问题的解析

 目前中国热轧厂采用的四辊轧机普遍存在工作辊夹住板带轴向的移动现象,简称“叼板窜辊”弊端。按“微尺度静定”设计理论分析得知,轧辊轴承座与机架窗口立柱之间的微小间隙约1 mm（后随衬板磨损加大）易使辊系处于静不定状态,进而产生辊间错位及交叉工况,因此在特定条件下会发生叼板窜辊现像。原有设置辊间偏移距布放辊系的设计忽视了控制微小间隙的必要性,经分析发现,叼板窜辊原因的关键在于科学控制“不得已间隙”。通过开发智能衬板,保证轧机轧辊平行、定位稳定、可靠运转,消除叼板窜辊带来的能量消耗,充分利用轧机的高档能力,采纳大压下轧制新工艺,生产高强度新品种精品,实现4/6辊热冷轧机改造和更新换代,达到降本増效的目的。     

Using rollers with increased barrel length in four-high mills

Increase in barrel length of the working rollers from 3100 to 3400 mm is proposed in the 3000 mill, without change in barrel length of the supporting rollers (2980 mm) or in the structure of the cell. Calculations of the pressure between the rollers and the transverse thickness variation of the rolled metal when the barrel length of the working rollers is 3100 and 3400 mm shows that the maximum pressure between the rollers is increased by 6–8% for 3400-mm working rollers with rolled sheet of maximum width 3200 mm; the rolled material is concave. To obtain a convex cross section, the depth of the bevel of the edges of the supportingroller barrel is doubled. Increasing the length of the working rollers in the 3000 mill at PAO Mariupol’skii Metkombinat im. Il’icha permits the production of commercial sheet with a width up to 3000 mm.     

宽带钢冷轧机辊系纵向刚度特性对比

针对目前广泛使用的CVC和HC两种主要轧机机型,利用大型有限元软件ANSYS 9.0建立了三维辊系有限元模型,分析了不同机型的四辊和六辊轧机在不同窜辊、弯辊工况下的轧制力纵向刚度和弯辊力纵向刚度的变化情况.在相同工况下的四辊轧机的轧制力纵向刚度要大于六辊轧机.中间辊窜辊或工作辊窜辊对HC轧机的轧制力纵向刚度和弯辊力纵向刚度的影响要大于CVC轧机.     

UCM冷连轧机边降控制工作辊辊形优化

国内大量应用的1 700 mm以下的UCM冷连轧机组不具备工作辊窜辊功能,只能依靠工作辊边部辊形设计对硅钢板带进行边降控制。提出了针对UCM冷连轧机的工作辊端部辊形设计方法,在大幅提高边降控制能力的同时,通过边部保护段的设计有效减少断带风险。辊形曲线有利于轧辊磨削,避免轧辊表面质量对带钢表面造成影响。充分利用工作辊与中间辊弯辊的板形调控特性,使用高效实用的弯辊力组合板形控制方法,对轧制过程中产生的二次和四次板形缺陷实施快速精确的控制,在控制硅钢边降的同时很好地抑制板形问题,具有重要的研究价值与推广前景。     

基于辊缝动态摩擦方程的铝板冷轧机垂振机理分析

针对高速铝板轧制过程中频繁出现的冷轧机垂直振动现象,结合轧制工艺润滑原理和机械振动理论,建立基于辊缝动态摩擦方程的轧机垂直振动模型.该模型由辊缝几何形状模型,轧辊-轧件工作界面的动态摩擦模型,变形区内的正向轧制应力、摩擦应力分布模型,以及单机架铝板冷轧机二自由度垂向系统结构模型组成.同时,为研究轧辊-轧件工作界面动态摩擦机制影响下的冷轧机垂振机理及系统稳定性,采用某厂单机架铝轧机设备及工艺参数,搭建Matlab/Simulink平台,分别模拟仿真轧制压力和正向轧制应力曲线,验证该模型的有效性;并讨论分析了变形区混合摩擦状态,轧辊-轧件表面粗糙度、轧件入口厚度与系统稳定性的关系.     

Effect of sliding and rolling friction on the energy-force parameters during hot rolling in four-high stands

A procedure for the calculation of the main-drive power for a hot-rolling wide-strip mill is developed. It takes into account that 85–99% of the lengths of the deformation zones in the working stands of such mills are occupied by stick zones, in which a strip undergoes static friction stresses (which do useful work only in the backward slip zone). This procedure also takes into account the rolling friction energy losses, which account for 83–93% of the power consumed for the rotation of idle backup rolls or 29–68% of the total energy consumed by the main mill drive. The average power calculation error for this procedure is 5%, and the maximum error is 10%, which is three to five times smaller than the errors of well-known calculation procedures. Our procedure has a high potential for revealing the reserves of decreasing the contact stresses in rolls and the saving of electric power via the redistribution of the reductions and tensions between stands and an increase in the temperature of the semi-finished rolled products.     

六辊冷连轧机中间辊横移过程辊间接触压力分析

 为了使轧机板形控制性能适应带钢规格材质变化,用于连续轧制高档冷轧薄带钢的六辊冷连轧机大都采取中间辊可横移技术。但是,中间辊横移必定使辊间接触压力分布更不均匀,导致出现接触压力尖峰。在中间辊横移过程中,辊间接触压力和横移阻力都会随横移速度的变化而发生改变,并可能导致辊间接触压力在轧辊端部形成更大的压力尖峰,从而造成轧辊磨损不均匀并缩短轧辊的使用周期。通过建立有限元仿真模型,以仿真模拟获得中间辊横移过程中辊间接触压力的变化规律后,优化设计轧辊辊形,并且提出使用非对称弯辊力的方法,实现了辊间接触压力的分布均匀化,降低了辊间接触压力尖峰值,并延长了轧辊的使用寿命。     

油膜轴承倾斜承载对冷连轧机启动的影响

针对某CVC带钢冷连轧机启动阶段支持辊油膜轴承静压承载能力不足的问题,应用流体润滑理论,建立了轴承倾斜工作下静压承载能力的全润滑系计算模型,分析了轧机压下倾斜、油泵功率和节流器液阻对轴承静压承载性能的影响.计算结果表明,压下倾斜过大会造成轴套与衬套的轴线出现倾斜,进而导致轴承的静压承载能力急剧下降,是造成轴承寿命缩短、连轧机启动频繁失败的根本原因.在实际生产中,限定了轧机压下倾斜设定值上限,增大了润滑油黏度,从而有效提高了轴承的承载能力,机组启动成功率显著提高.     

Reduction mills in helical rolling

The use of helical reduction mills is considered. Their scope in terms of rolling speed and deformation is assessed. The design and application of such mills is analyzed. A refined method is proposed for determining the width of the contact surface and the energy parameters. Experimental data are presented.     

冷连轧机SmartCrown轧辊磨损辊形对板形调控能力影响

针对宽带钢冷连轧机首次应用的SmartCrown板形控制技术,通过对SmartCrown轧辊大量实测得到了轧辊磨损辊形,采用遗传算法建立了轧辊磨损预报模型,并利用ANSYS软件建立了三维辊系有限元分析模型,研究了磨损辊形对SmartCrown板形控制技术在服役过程中板形调控能力的影响,提出了新辊形使用工艺策略．     

Benefits of Steckel mills in rolling

The development of Steckel mills is reviewed, along with their advantages and disadvantages. In recent years, mills with heated coiling units have been widely adopted for the production of an extensive range of hot-rolled sheet and strip. New mechanical and organizational approaches are considered. Steckel mills are found to be expedient for use in mini mills and in casting and rolling systems.     

Effects of powder material and process parameters on the roll compaction,sintering and cold rolling of titanium sponge

ABSTRACT

Roll compaction is a powder metallurgy process that has the potential for cost reduction in the production of titanium parts. In this study, experiments were carried out to investigate the effects of powder type and size on the roll compaction and subsequent sintering and cold rolling behaviour of titanium powder. Powders used ranged in upper sieve sizes from 0.15 to 3?mm. Strip density was found to increase with decreasing powder size while thickness decreased. Following sintering in the range of 800–1200°C, cold rolling was performed with various levels of thickness reduction. Average (across the width) densities of up to 88% were achieved, with higher density regions in the middle of the strips reaching up to 99%. Roll force was measured during cold rolling and found to increase with increasing final (post-cold rolling) density and also with increasing roll gap reduction amounts.