不锈钢冷轧过程中的异常现象浅析

针对使用偏八辊轧机辅助轧制油的不锈钢冷轧过程中出现的异常现象,如轧制力过大、起火、板面有色差、板面有伤痕、板面清洗性不好、烧辊、轧机颤动、板形不好、板面腐蚀等,从轧制工艺、设备状态、轧制油等方面进行分析,提出相应的解决对策,以保证轧出不锈钢板带的质量,并列举了一些成功应用案例。     

Experimental Support for the Dynamic Concentration Theory of Forming an Oil Reservoir at the Inlet of the Roll Bite by Measuring the Onset Speed of Starvation as a Function of Oil Concentration and Droplet Size

The dynamic concentration theory describes a mechanism of how an oil reservoir forms at the inlet of the roll bite when an emulsion is used as the lubricant. This theory assumes that oil droplets larger than the thickness of the lubricant film in the deformation zone become trapped when they come into contact by both the surface of the sheet and the surface of the work roll. As the droplets move toward the deformation zone, water is left behind or squeezed out by the flattening of the oil droplets. At some point, the surfaces of the trapped oil droplets come into contact with each other, resulting in an inversion where oil becomes the continuous phase. The dynamic concentration theory predicts that the height of the meniscus where this inversion occurs is a function of the percent oil concentration and the diameter of the oil droplets. To test the dynamic concentration theory, the onset speed of starvation on a laboratory rolling mill was determined by measuring the speed in which load increases relative to the load measured for the same process but where the lubricant film is fully flooded. Both the concentration of oil and the size of the monodisperse oil droplets were varied to change the height of the meniscus and consequently the onset speed of starvation. Solid support for the dynamic concentration theory was obtained when starvation occurred at the same speed for emulsions with different oil droplet sizes in which their concentrations were specifically adjusted so that their meniscus heights theoretically were the same. Finally, an unexpected consequence of the dynamic concentration theory was that the thickness of a starved lubricant film is independent of rolling speed, but this is only true at high speeds.     

高性能不锈钢冷轧轧制油的研制：Ⅰ基础油和助剂的筛选

不锈钢冷轧轧制生产工艺和工况(高速、高温、高压)比较苛刻,轧制不锈钢板带质量要求甚高,因而对不锈钢冷轧轧制油的性能要求很高。研究高性能不锈钢冷轧轧制油基础油和添加剂的配伍性,基于挥发性、表面张力和抗氧化能力3个指标筛选出最佳的基础油,基于抗老化性和黏度2个指标筛选出最佳的抗氧剂,基于磨斑直径与摩擦因数2个指标筛选出最佳的润滑剂;基于最大无卡咬负荷、烧结负荷和摩擦因数3个指标筛选出最佳的助剂。在此基础上,筛选得到了最佳的不锈钢冷轧轧制油配方。     

Control of surface thermal scratch of strip in tandem cold rolling

The thermal scratch seriously affects the surface quality of the cold rolled stainless steel strip. Some researchers have carried out qualitative and theoretical studies in this field. However, there is currently a lack of research on effective forecast and control of thermal scratch defects in practical production, especially in tandem cold rolling. In order to establish precise mathematical model of oil film thickness in deformation zone, the lubrication in cold rolling process of SUS410L stainless steel strip is studied, and major factors affecting oil film thickness are also analyzed. According to the principle of statistics, mathematical model of critical oil film thickness in deformation zone for thermal scratch is built, with fitting and regression analytical method, and then based on temperature comparison method, the criterion for deciding thermal scratch defects is put forward. Storing and calling data through SQL Server 2010, a software on thermal scratch defects control is developed through Microsoft Visual Studio 2008 by MFC technique for stainless steel in tandem cold rolling, and then it is put into practical production. Statistics indicate that the hit rate of thermal scratch is as high as 92.38%, and the occurrence rate of thermal scratch is decreased by 89.13%. Owing to the application of the software, the rolling speed is increased by approximately 9.3%. The software developed provides an effective solution to the problem of thermal scratch defects in tandem cold rolling, and helps to promote products surface quality of stainless steel strips in practical production.     

板带钢冷轧乳化液及润滑效果研究

针对冷轧无间隙原子钢(IF钢),配制了2种不同的乳化液,并将其与国内、国外商品级乳化液的冷轧实验进行对比。实验发现乳化油中基础油的选择对乳化液冷轧润滑效果的影响很大,当基础油含饱和脂肪酸高时乳化液润滑能力好,可以用乳化液皂化值来衡量乳化油冷轧润滑效果的优劣。一般皂化值高的乳化液可用来冷轧屈服强度较高、成形较困难的板带钢。使用乳化液冷轧后的表面形貌明显优于无润滑状态的轧后表面。在乳化液冷轧润滑过程中,当压下率较低时,轧件的表面质量有所改善,总压下率超过90%以后,轧件的表面质量又呈下降趋势。     

罐式集装箱罐体用不锈钢板表面质量控制研究

从提高罐式集装箱的原材料---316L不锈钢板表面质量的角度出发,通过对不锈钢冷轧过程中乳化液相关参数的优化,开发了一套适合于罐式集装箱用不锈钢原板的表面质量综合防治技术,并直接应用于现场,获得了良好的效果。     

Experimental and numerical study of O/W emulsion lubricated strip rolling in mixed film regime

An experimental and numerical study of cold rolling lubricated by O/W emulsion has been carried out. The strip rolling experiment was carried out on a Hille experimental rolling mill with a view to study the performance of emulsion lubrication in terms of practical rolling parameters. Accordingly, rolling parameters such as rolling force and torque were measured. The experimental measurements compare favourably with the computed results from a numerical scheme developed by the authors. The scheme, based on a two-phase lubricant model, is capable of calculating the oil concentration at any point within the inlet zone and work zone, rolling pressure, film thickness, and fractional contact area ratio associated with strip rolling under mixed film lubrication at different rolling speeds. Using this scheme, the intertwined effects of an emulsion’s parameters such as: oil concentration, mean oil droplet size, and rolling speed on strip rolling were investigated. The numerical study encompassed the mixed film regime for speed, S ranges from 10⁻⁴ to 10⁻², supply oil concentration level λ_ds from 1 to 10%, and oil droplet size D _S from 5 to 10. Experimentally, the differences between water, oil and emulsion-lubricated rolling are not discernible except for film thickness. At a low speed of 10 RPM, force and torque of water-lubricated rolling are marginally higher than oil- or emulsion-lubricated ones. However, the difference between emulsion and neat oil is not apparent. The numerical results show the occurrence of a moderate oil concentration increase in the inlet zone followed by a sharp one at the beginning of the work zone. The effect of the concentration process is predominantly seen in the film thickness and the lubricant pressure whilst its effect on the total pressure is less pronounced. The analysis of the results suggests that it is possible to lower the emulsion oil concentration without any adverse effect on the rolling process. This principle can be used to control the outlet lubricant film thickness and hence the surface quality of the rolled strip.     

H68黄铜热轧润滑油的研制及应用

根据亲水亲油平衡（Hydrophile-Lapophile Balance，HLB）理论，通过选择合适的乳化剂、抗磨剂、极压剂、防锈剂等添加剂，研制成适用于硬态黄铜（H68，H70和H72）的热轧乳化液，成功地应用于2Cr13不锈钢焊态热轧辊初轧多种硬态黄铜板材，取代了目前铜加工生产中，对于硬态黄铜普遍使用润滑脂间歇式地润滑热轧辊的工艺。生产结果表明：由于采用直接连续地喷射乳化液到轧辊表面，容易控制板形和板材的尺寸；提高了轧辊的抵抗磨损和防止粘辊的能力，克服了铜带表面的“黑丝”、“发黄”和粗糙化现象，稳定地改善了铜带表面的质量，降低了工人劳动强度，从而极大地提高了生产效率并延长了轧辊的使用寿命。     

Starvation Behavior in Cold Rolling of Aluminum with Oil-in-Water Emulsion

Reich, et al. ( 1 Reich, R., Panseri, N. and Bohaychich, J. 2001. “The Effects of Lubricant Starvation in Cold Rolling of Aluminum Metal When Using on Oil-in-Water Emulsion,”. Lubrication Engineering, 57: 15–18.  [Google Scholar] ) reported that the rolling force for the cold rolling of aluminum increased when starvation occurred in the oil-in-water (O/W) emulsion used as the rolling fluid. They reported that the starvation occurrence was dependent on the emulsion concentration and the size of the oil droplets, but the thickness of a starved lubricant film was independent of the rolling speed. However, from their experimental results, the cause of the increase of the rolling force and the quantitative inlet oil film thickness at the entrance between the roll and the workpiece for the O/W emulsions cannot be understood. In this study, the aluminum rolling experiments using O/W emulsions with different concentrations were carried out in order to reproduce the increase of the rolling force. Experiments were carried out using a laboratory mill with two high rolls. The workpiece material was an aluminum A1050-H. Commercial rolling oil was used as base oil for the aluminum emulsion. The rolling force was measured during the rolling and the appearance of the workpiece after rolling was taken. Moreover, the effect of the surface roughness of the rolls on the increase of the rolling force was investigated. The increase of the rolling force was reproduced in the aluminum rolling with the O/W emulsion using the laboratory rolling mill. It was observed that the increase of the rolling force occurred after the oil starvation, and it depended on the oil starvation, the oil film thickness, the surface roughness of the roll, the rolling speed, and the reduction in thickness.     

高性能不锈钢冷轧轧制油的研制：Ⅱ 性能测试*

轧制工艺的发展和市场对轧制不锈钢板带日益提高的质量需求使得轧制油的性能也提出更加严格的要求。在前期配方研发的基础上,对研制的最佳配方的高性能不锈钢冷轧轧制油的挥发性、冷却性、渗透性和退火清净性等性能进行研究,并对现场应用效果进行考察。结果表明,研究的轧制油产品的挥发性低、冷却性好,具有优异的渗透性和退火清净性,各项性能指标接近或者优于进口同类产品,可完全替代进口轧制油。     

A thermal analysis of strip-rolling in mixed-film lubrication with O/W emulsions

Increase of both roll and strip surface temperatures can significantly affect a rolling process, roll conditions and strip mechanical properties. A comprehensive thermal analysis in cold rolling, especially in a mixed film regime, is needed to understand how thermal fields develop in roll and strip during rolling. It requires a simultaneous solution of the mixed film model for friction in the roll bite and the thermal model for roll and strip thermal fields. This paper presents a numerical procedure to analyse strip rolling process using lubrication with oil-in-water (O/W) emulsions. The thermal model includes the effect of heat generation due to the strip deformation and frictional shear stress at the asperity contacts. The numerical analysis employs a coupled thermal model and a mixed film lubrication model for calculating the friction and the asperity deformation in the bite. The thermal model considers the initial temperatures of the roll and strip, temperature rise due to the strip plastic deformation and friction. While the O/W mixed-film lubrication model takes into account the effect of surface roughness and oil concentration (%vol) of the emulsion. The thermal effect is analysed in terms of strip surface temperature and roll temperature, which are influenced by rolling parameters such as reduction, rolling speed, oil concentration in the emulsion. The results of the parametric study indicate that the effect of oil concentration on the thermal field is relatively small compared to that of reduction ratio and rolling speed. The reduction ratio increases the maximum interface temperature in the roll bite. In the mixed film regime, rolling speed also increases the maximum interface temperature and alters the temperature field of the strip. The numerical procedure was validated against known experimental data and can readily be extended to hot rolling or used to analyse roll strip temperature subjected to different cooling system.     

Experimental study of the disturbed layer generation during hot rolling contact of aluminum with steel

Effects of rolling passes and forward speed on the generation of disturbed layer on aluminum alloy sheet surfaces were investigated using a hot rolling simulator at forward speeds of −1% and 12% in presence of spraying emulsion. The results showed that at higher forward speed and number of rolling passes, the localized shear deformations become more pronounced on the surface. However, when the two rolling passes were in opposite directions, the localized shear deformations did not stick out, but were embedded into the aluminum surface. The defects generated were representative of the initial stages of the disturbed layer formation.     

轧辊表面微凸体形貌激光毛化技术的试验研究

以冷轧薄钢板冲压过程合理形貌的摩擦学设计为基础,对采用YAG脉冲激光器加工轧辊表面的微凸体形貌的机理进行了分析,并对主要加工参数的控制进行了试验研究。试验证明：激光输入功率密度在33 kW/cm2≤?S,P≤75 kW/cm2范围内,离焦量+0.10～+0.15 mm,激光扫描频率5 Hz,脉宽分别为0.5 ms,并采用功率增益功能,氩气保护时,可以加工出微凸体形貌。微凸体形貌制备试验的成功为进一步研究平整形貌复映关系和研究具有规则光滑凹坑表面形貌冷轧薄钢板的冲压性能提供了基础。     

Development of a meta-stable semi-synthetic lubricant for cold rolling of steel

A semi-synthetic meta-stable oil system for cold rolling of steel was developed as a substitute for a mineral oil based ‘stable emulsion’-type soluble oil. The developed oil system, comprising a ‘coating oil’ for post-pickling application and a ‘rolling oil’ for the rolling operation, was tested in the laboratory and subsequently subjected to extensive field trials in an integrated steel plant. Use of the developed oil system resulted in 25–50 per cent lower roll loads and 30–50 per cent reduction of inter-stand tensions compared with the mineral oil-based ‘stable emulsion’. It was also possible to increase the ‘strip reduction ratio’ and input coil width with the use of the newly-developed oil. Overall performance of the new semi-synthetic oil was found to be far superior to that of the mineral oil based ‘stable emulsion’.     

不锈钢冷轧工艺用油过滤系统介绍及比较

介绍了不锈钢冷轧工艺润滑油，包括轧制油与修磨油的工作循环过程．着重介绍了几种典型的油品过滤方式，并比较分析了其使用特点，提出了选择依据。     

铝材冷轧变形区油膜形成机理及影响因素

通过计算分析与轧制实验，探讨了名材冷轧变形区油膜形成机理及影响因素结果表明：流劝动力学成膜机理主要依赖于润滑剂粘度和轧制速度，特别是润滑剂粘度较氏时，轧制速度必须达到一定值，否则无法形成有效的油膜，而机械夹带作为低粘，低速条件下变形区主要成膜机理，其膜厚度依赖于轧辊与轧件粗糙度和夹带系数ｍ，０．１〈ｍ〈０．５，且随润滑剂粘度提高而增大。     

Mixed film lubrication of strip rolling using O/W emulsions

A numerical study on the oil concentration effect of O/W emulsion in cold rolling operating in the mixed film lubrication regime has been carried out. The developed scheme is able to calculate oil concentration at any point within the inlet zone (IZ) and work zone (WZ), rolling pressure, film thickness, and contact ratio for various rolling speeds. Hence the intertwined effects of oil concentration of the supplied emulsion and rolling speed on strip rolling are discussed. The study encompasses mixed film regime with speeds S range from 10⁻⁵ to 10⁻³ and supplied emulsion's oil concentration levels λ_ds range from 5% to 90%. The result shows that a moderate rise in oil concentration occurs in the IZ followed by a rapid one at the beginning of the workzone. In most cases, the oil in the emulsion would have been transformed from disperse phase to continuous phase throughout the WZ. Notwithstanding further concentration, which depends on the oil concentration of the supplied emulsion, could still occur in the WZ. The effect of the concentration process is predominantly seen in the development of the lubricant pressure whilst its effect on the total pressure is less pronounced. The analysis of the results suggests that it is possible to lower the emulsion oil concentration without detrimental effects on the rolling process; and from the analysis of the outlet film thickness, it is shown that the variation of emulsions’ oil concentration could control the exit lubricant film thickness and consequently the strip surface quality.     

Analytical and experimental study on asymmetrical sheet rolling

An analytical model assuming constant shear friction between the rolls and sheet is proposed to explore the characteristics of asymmetrical cold and hot sheet rolling. In the hot sheet rolling process, the surface friction stress is assumed to be equal to the yield shear strength (i.e. τ = k). As the friction factor m is less than 1, the simulation for the cold rolling process can be conducted. To verify the validity of the proposed analytical model, a series of experiments on asymmetrical cold sheet rolling of aluminium are carried out. The total rolling force and the forward slip are measured. The proposed model is also used to estimate friction factor (m) with the measured forward slip. With the estimated friction factors, the analytical rolling forces are calculated to compare with experimental data. Reasonable agreement is found. By this proposed analytical model, it is noted that a large amount of calculation time and computer expense are saved, and the characteristics of asymmetrical cold and hot sheet rolling are obtained easily and rapidly.     

冷轧压下率和退火工艺对St37-2G结构用冷轧钢板组织和力学性能的影响

研究了冷轧压下率和退火工艺对St37-2G结构用冷轧钢板显微组织和力学性能的影响,并优化了生产工艺。结果表明:试验钢板经不同压下率冷轧并经670℃×5h退火后的显微组织均由铁素体、少量渗碳体和微量珠光体组成,仍保留着渗碳体沿轧向呈纤维状分布的特征;随着冷轧压下率的增大,试验钢板的硬度先增大后减小,在冷轧压下率60%时达到最大值;随退火升温速率的增大,试验钢板的屈服强度、抗拉强度以及塑性应变比明显下降,伸长率和加工硬化指数变化不大;最优的冷轧和退火工艺为冷轧压下率40%～50%,退火温度670℃,升温速率20℃·h-1。     

冷轧钢板轧制乳化液的研制

介绍了用于冷轧钢板轧制的水基型轧制液的性能要求,根据使用要求制定了产品的性能指标,并讨论了各种性能指标的测试方法.通过对基础油和添加剂进行选择和复配,研制出一种具有优异的抗磨、抗泡、防锈和防腐蚀性能的水基型轧制液.该轧制液由精制矿物油与表面活性剂、抗磨剂、油性剂、抗氧剂和防锈防腐剂等添加剂调和而成,在钢板轧制过程中能起到冷却、润滑和清洗作用,与目前国内使用最多的荷兰奎克公司N428和N460等系列产品水平相当.