基于热混合润滑的钢/橡胶接触表面水润滑增强调控

目的 增强钢/橡胶摩擦副的润滑性能,为提高混合润滑状态下水润滑轴承的性能提供参考。方法 建立水润滑条件下钢/橡胶摩擦副的热混合润滑模型,讨论热效应对润滑性能的影响,并在此基础上进一步研究表面粗糙度、水基润滑剂黏度和供水压力对水润滑增强调控的作用。结果 与等温解相比,热效应使Stribeck曲线发生了右移,摩擦因数和载荷比增大,膜厚比降低。最高水膜温度随着转速的增加而升高,热效应对混合润滑性能的影响显著。减小摩擦副表面粗糙度,Stribeck曲线向左移动。在相同转速下,载荷比随着表面粗糙度的减小而降低,膜厚比反之。表面粗糙度越大,水膜温度越高,最高温度位于出口区,且钢的表面温度低于水膜和橡胶的表面温度。当水基润滑剂的黏度增大时,膜厚比增大,载荷比和最高水膜温度降低,Stribeck曲线发生左移。增加供水压力可以改善水膜压力分布,使水膜承载区增大、压力减小,粗糙峰接触压力和承载区减小,导致载荷比减小、膜厚比增加,Stribeck曲线向左偏移,水膜最高温度降低。当接触区由边界润滑向混合润滑过渡时,水膜最高温度出现拐点,且水膜最高温度拐点随着供水压力的增加而左移。结论 热效应会降低摩擦副的混合润滑性能,因此在混合润滑中不能忽略。考虑热效应时,通过减小表面粗糙度,或增加水基润滑剂黏度和供水压力,均有利于增强钢/橡胶接触表面水润滑的混合润滑性能。     

二次冷轧乳化液管路直混润滑系统设计及关键设备选型

在分析了传统二次冷轧机组乳化液直喷润滑系统的基础上,充分考虑到二次冷轧机组的设备与工艺特点,提出了一套适合于二次冷轧机组的乳化液管路直混润滑系统设计方案,完成了静态混合器、水泵、油泵、流量计、压力表和电控柜等关键设备的选型,开发了一套完整的二次冷轧机组乳化液管路直混润滑系统,并将其应用到某1220二次冷轧机组的生产实践,选取典型规格的DR8M钢种进行现场轧制试验,对比分析了轧制工艺参数、板厚波动与板形质量波动情况。分析结果表明:二次冷轧机组乳化液管路直混润滑系统有效地提高了升降速过程轧制压力的稳定性,降低了轧制能耗与油耗,减小了带钢厚度偏差与板形值波动。     

表面织构及供油量对润滑性能影响的建模分析

目的研究不同供油条件下织构表面的润滑性能。方法首先,建立考虑表面织构的乏油润滑模型,求解修正雷诺方程获得乏油工况下考虑织构表面的润滑油膜厚度以及压力分布。然后,依据求得的润滑油膜厚度判断计算域内各点润滑状态,通过接触压力及油膜厚度分别计算边界润滑、混合润滑以及流体润滑状态下的切应力,并积分求得摩擦力进而得到摩擦系数。结果模拟了供油层厚度为50~500 nm以及充分供油条件下三种织构的润滑行为,获得了不同润滑状态下表面织构的摩擦系数。速度为0.1 m/s时,供油量对接触区油膜厚度的影响较小,不同润滑状态下织构表现出不同的润滑性能。速度为0.2 m/s时,供油层厚度对油膜厚度的影响较大,随着供油层厚度的增大,膜厚明显增加,摩擦系数在供油层厚度为200 nm时最小。结论接触副处于流体润滑状态时,织构表面不具有减摩效果。接触副处于边界润滑状态时,织构表面具有减摩效果,并且织构较密时,摩擦系数较小。接触副处于混合润滑状态时,织构过于稀疏或密集时均不具有减摩效果,但是合理分布的织构具有减摩效果。     

铝箔轧制润滑机理和速度效应的研究

从速度效应人手研究了一定条件下铝箔轧制变形区内润滑状态的变化。由轧制速度与油膜厚度、轧制速度与铝箔表面粗糙度以及油膜厚度与表面粗糙度的关系等三方面得出的结果具有良好的一致性。     

时变效应对轧辊轴承热弹流润滑的影响

介绍了时变效应对于乳化液热弹流润滑轧辊轴承的影响,对比了稳态与时变条件下的热弹流润滑膜的压力与膜厚。建立了考虑时变效应的乳化液润滑轧辊轴承热弹流润滑数学模型,利用压力求解的多重网格法和弹性变形的多重网格积分法,得到了时变条件下乳化液热弹流润滑轧辊轴承的数值解。计算结果表明:时变效应对于热弹流乳化液润滑膜压力的影响很小,但对于膜厚的影响却很大,即时变效应时乳化液的润滑膜厚明显变薄。     

时变效应对轧辊轴承热弹流润滑的影响

介绍了时变效应对于乳化液热弹流润滑轧辊轴承的影响,对比了稳态与时变条件下的热弹流润滑膜的压力与膜厚.建立了考虑时变效应的乳化液润滑轧辊轴承热弹流润滑数学模型,利用压力求解的多重网格法和弹性变形的多重网格积分法,得到了时变条件下乳化液热弹流润滑轧辊轴承的数值解.计算结果表明:时变效应对于热弹流乳化液润滑膜压力的影响很小,但对于膜厚的影响却很大,即时变效应时乳化液的润滑膜厚明显变薄.     

混合润滑轧制入口膜厚模型

运用平均流动模型求解混合润滑轧制变形区入口膜厚问题时,提出了混合因子φm,它综合了流动因子φx和接触因子φc对入口膜厚的影响,简化了轧制润滑模型,计算和实验表明,在流体润滑条件下,表面粗糙效应形膜亦有一定的影响,也即混合因子φm还适用于流体润滑轧制,且修正了未考虑表面粗糙效应而引起的不足。     

铝板带热轧工艺润滑乳化液的应用与发展

随着铝及铝合金热连轧技术的广泛应用,乳化液热轧工艺润滑的作用越来越重要。为此从热轧乳化油黏度、乳化液的粒径、使用浓度、稳定性及添加剂等方面入手,探讨了影响乳化液润滑效果的因素。针对热连轧乳化液在选择、使用、维护、管理过程中存在的诸如粗轧、精轧是否含皂,轧后板面存在色差等问题,提出了解决问题的思路和办法。     

铜板带冷轧乳化液润滑效果研究

在单因素筛选实验基础上,对硫系油性润滑添加剂(SCO)和磷系极压润滑添加剂(T306)复合使用的配伍效应进行了深入地研究.实验表明,当SCO含量为2%和T306含量为0.6%复合使用时,两者的配伍性能最差,而SCO含量为2%和T306含量为4%复合使用时,两者的配伍性能最好,轧制润滑实验表明,采用优化的乳化液轧制后,铜板带表面质量明显提高.     

油水两相流润滑轧机油膜轴承的摩擦行为分析

目的研究含水润滑油对轧机油膜轴承的摩擦学性能的影响。方法选取轧机油膜轴承为研究对象,利用油水两相流体数学模型和弹流润滑方程研究轧机油膜轴承在等温条件下的润滑特性,分析油水两相流体润滑膜的压力、膜厚分别随含水率、滑滚比、轴颈间隙、主轴转速和轧制力的变化关系。结果水介入润滑油之后,随着含水率的增加,油水两相流体的黏度先增加,在含水率为30%左右时达到最大值(0.08 Pa·s),之后又迅速减小,直至接近于纯水的黏度(0.001 Pa·s)。当含水率为30%时,无量纲膜厚达到最大值(0.82),当含水率为90%时,无量纲膜厚达到最小值(0.68)。结论随着含水率的增加,油水两相流体由油包水流型转化为水包油流型,压力变化不大,膜厚先增加后减小,作为润滑剂,油包水流型比水包油流型具有更好的润滑性能,且在流型转变点处的润滑性能最优。随着滑滚比和轧机油膜轴承主轴转速的增加,压力减小,承载能力减弱,膜厚增加,润滑性能增强。随着轴颈间隙和外部轧制力的增加,压力增加,承载能力增强,膜厚减小,润滑性能减弱。     

Modeling of the inlet zone in the mixed lubrication situation of cold strip rolling

In this paper a method to simulate the oil thickness and length of elastic deformation in the inlet zone of cold rolling has been developed. The mixed film lubrication model was adopted to describe the behavior of the lubricant and asperity deformation. The elastic Von Karman equation was used to describe the elastic deformation of strip in the inlet zone. The length and lubricant film thickness of the inlet zone can be obtained by a numerical method. Results of simulations show that the reduction, rolling speed, back tension have a significant influence on the lubricant film thickness and the inlet zone length.     

辊缝油膜承载力对冷轧机振动的影响

针对某冷轧厂在线轧制过程中轧机的振动问题,从辊缝油膜承载力的角度分析其对轧机振动的影响,得出轧制过程中辊缝间距的减小导致辊缝油膜需提供更大的承载力来维持轧机稳定。从乳化液浓度、轧辊转速、乳化液金属微粒含量方面探讨了增强辊缝油膜承载力的方法,得出乳化液浓度与轧辊转速在增强油膜承载力的同时减小了辊缝的摩擦系数,也易导致轧机振动。通过试验得出,调节乳化液金属微粒含量能够在原有摩擦系数的基础上增强辊缝油膜承载力,从而保证轧机的稳定运行。     

Measurements of friction during hot rolling of aluminum strips

In order to establish the dependence of the coefficient of friction on rolling speed and the reduction, commercially pure aluminum strips were rolled at 500°C, using a 2% oil/water emulsion as the lubricant. The roll separating forces, roll torques, the forward slip, the roll pressure and the interfacial shear stress were measured as a function of the reduction and the rolling speed. The coefficient of friction was determined from the shear stress and the roll pressure distributions and its magnitude was validated independently. The coefficient of friction was found to increase with reduction and, in general, decrease with rolling speed. The adhesion theory of friction has been used to explain the observations.     

An efficient thermal analysis for the prediction of minimum film thickness in inlet zone at high speed lubricated cold strip rolling

The main objective of this work is to develop a formula for the prediction of thermal minimum film thickness at the roll/strip contact in terms of operating parameters particularly at the elevated roll speeds. The film thickness at the exit of inlet zone and at the entry of contact zone is common. Therefore, in order to compute minimum film thickness accurately at the contact, an efficient thermohydrodynamic analysis of fully flooded inlet zone has been carried out. The effects of rolling speed, reduction ratio, material parameter and slip on minimum film thicknesses (isothermal and thermal) and maximum film temperature rise (in the inlet zone only) are rigorously investigated. The performance parameters in the lubricated domain have been evaluated for rolling speeds (up to 20.0 m/s), reduction ratios (0.05–0.20), and slip values varying up to 20%. Significant reduction in minimum film thickness (thermal) has been observed with the increase in the rolling speed and slip. Based on this study, empirical relations are developed for the prediction of minimum film thicknesses (isothermal and thermal) at the contact. A relation for evaluation of maximum film temperature rise in the inlet zone has been also developed. Authors believe that the empirical relations presented herein may be useful for designers and practicing engineers.     

铝箔冷轧工艺润滑状态与润滑效果研究

铝箔冷轧工艺润滑中,采用综合考虑变形区膜厚比、摩擦因数、轧后表面质量与轧制油添加剂影响性相结合的方法,综合评价润滑状态。结果表明:入口处的油膜厚度明显小于综合表面粗糙度,获得的轧后铝箔表面质量较好,轧后铝箔表面粗糙度都比仅加入基础油时的有所降低,添加剂已经发挥作用,润滑状态以边界润滑为主。     

基于油膜力的油膜厚度补偿模型的研究与应用

为了满足轧制中带钢厚度精度的控制要求,必须对由轧制速度变化引起的带钢厚度波动进行油膜补偿.提出了一种基于油膜力的油膜厚度补偿方法,并进行推证,得到适合现场应用的数学模型.以此数学模型为基础,开发了一套完整的数据采集、数据处理和现场应用方法,并将该模型成功应用于热连轧生产中.实际应用表明,对热连轧机组采用该油膜厚度补偿算...     

轧制变形区油膜厚度的实验研究

就轧制变形区油膜厚度的不同测试方法进行了对比研究,提出了简便、衫的加热退火法。方法研究了轧制油粘度,轧制速度与压下率对轧制变形区油膜厚度的影响。     

Prediction of effect of rolling speed on coefficient of friction in hot sheet rolling of steel using sliding rolling tribo-simulator

In order to reduce the rolling force and the roll wear, the lubricants have been used in hot rolling of steel. In order to evaluate the tribological behavior at the interface between roll and workpiece in hot steel rolling, it is important to measure the coefficient of friction and examine the effect of the tribological factors on the coefficient of friction. In this paper, the effect of the rolling speed on the coefficient of friction is investigated using the tribo-simulator testing machine for hot rolling developed by the authors. The workpiece used is SPHC. The roll material is SKD11 and the surface roughnesses are 0.05 μm, 0.2 μm and 0.8 μm. The rolling tests are carried out at a temperature of 800 °C during a rolling distance of 400 mm, changing the rolling speed from 15 to 70 m/min. The colza oil is used as a base oil and the emulsion concentrations are 0.1% and 3.0%. The coefficient of friction at an emulsion concentration of 3.0% is independent on the rolling speed. On the other hand, the coefficient of friction at an emulsion concentration of 0.1% decreases with increasing rolling speed in the lower range of rolling speed, but it increases in increasing rolling speed in the higher range of rolling speed.