基于Teager能量算子和EEMD的滚动轴承故障诊断方法

针对应用集合经验模态分解(ensemble empirical mode decomposition,EEMD)方法难以提取强噪声背景下滚动轴承微弱故障特征的问题,提出了将最小熵反褶积(minimum entropy deconvolution,MED)和小波阈值去噪与EEMD相结合的改进方法.先采用MED对滚动轴承振动信号降噪,增强冲击特征;然后利用基于EEMD的小波阈值去噪方法处理降噪后信号得到一组固有模态分量(intrinsic mode function,IMF),并依据相关系数准则剔除虚假分量;对重构后信号进行Teager能量算子解调分析,提取其微弱故障特征.通过仿真信号和实验台信号验证了该改进方法的有效性.     

冷轧界面油膜厚度对表面形貌转印过程的影响

为研究冷连轧过程中接触界面润滑油膜厚度对表面形貌转印过程的影响,在跟踪实际生产中带钢表面形貌的基础上,结合轧辊表面磨损形貌以及润滑分析确定的界面油膜分布,建立真实表面接触的带钢形貌生成模型,用跟踪测量轧辊服役期内生产带钢表面的粗糙度对模型进行验证.利用模型分析在不同磨损状态下电火花毛化轧辊油膜厚度对转印形成带钢表面形貌的影响规律.结果表明:轧辊表面处于不同磨损状态时,带钢表面Ra的转印率随着油膜厚度的增加而减小;轧辊表面磨损后转印形成的带钢表面P_c的转印率在油膜厚度增加的初期基本保持不变,而后急剧减小.     

基于振动响应机理的轴承故障定量诊断及量化分析

为了解决轴承损伤尺寸难以诊断的问题,建立滚动轴承非线性振动的动力学模型,并通过解析法求解轴承4种不同大小的故障振动信号响应,根据故障轴承响应信号的双冲击时间间隔对轴承故障进行定量分析,分析结果表明了该定量分析方法的准确性.进而对多组不同故障大小的轴承数据进行统计学分析,建立了轴承外圈损伤程度区间.滚动轴承外圈实验结果验证了提出的基于故障机理的轴承故障定量诊断方法的有效性.     

冷连轧过程控制中轧制力和前滑模型的综合自适应

为了提高冷连轧过程控制系统中轧制力模型的设定精度,提出了一种轧制力和前滑模型的综合自适应算法.通过建立综合自适应目标函数,以变形抗力和摩擦系数模型中的自适应系数作为寻优参数,并采用Rosenbrock算法求解目标函数,可以同时得到满足轧制力模型和前滑模型计算精度的自适应系数.该模型自适应算法可成功应用于某1 450 mm冷连轧机组.结果表明,采用该模型的综合自适应算法后,轧制力设定精度显著提高,且满足在线控制要求.     

Effect of electromagnetic and ultrasonic cast rolling on microstructure and properties of 1050 aluminum substrate for presensitized plate

The 1050 aluminum alloy strip was prepared by means of electromagnetic and ultrasonic cast rolling on the modified asymmetric twin roll caster, and then the aluminum substrate for presensitized plate was prepared through cold rolling and annealing.The effects of electromagnetic and ultrasonic cast rolling on microstructure, mechanical properties, surface roughness and electrolytic corrosion properties of 1050 aluminum substrate were studied. The results show that electromagnetic and ultrasonic cast rolling can decrease the average crystallite size of aluminum substrate by 5 μm, increase the crystal boundaries with uniform distribution, and make the second-phase particles with smaller size distributed dispersively in the substrate, meanwhile, it can increase the tensile strength, elongation and micro-hardness by 4.58%, 9.85% and HV 2, respectively, reduce the surface roughness, make the surface appearance more even, electrolytic corrosion polarization curve of aluminum substrate more smooth and the surface corrosion pits with regular shape more dispersive.     

基于惩罚项的热连轧轧制规程多目标函数优化

为了解决传统热连轧负荷分配优化普遍采用约束方法进行求解时求解步骤繁琐、不容易获得最优解的问题,提出了一种惩罚函数算法.通过引入函数惩罚项,将多目标函数约束求解问题转化为无约束求解问题.建立了带有惩罚项的轧制力、板形、功率和温度的单目标函数,进而采用线性加权求和法建立了综合多目标函数.利用Nelder和Mead单纯形解法则进行求解,简化了求解的步骤,最终得到了兼顾轧制力平衡、板形最优及温度合理的负荷分配方案.实际应用效果表明,与传统负荷分配方式相比,基于多目标优化得到的轧制规程更符合实际生产要求,具有良好的应用前景.     

变直径空心件楔横轧收口模拟研究

采用楔横轧技术,对变直径空心件收口成形工艺进行研究。根据工件尺寸,使用UG建立不同方案下的模具,将模具设计和数值模拟相结合,模拟工件的成形过程。对比模拟结果,得出最佳的成形方案,并改进成形工艺参数,最终确定了变直径空心件楔横轧工艺的成形方案。     

滚动直线导轨副综合试验台加载系统优化设计

针对滚动直线导轨副综合试验台加载的需求,通过对比分析选择出最佳加载方式,然后对液压加载系统进行设计,并对加载系统中的关键部件龙门架进行有限元分析和优化设计,设计出一套适合于滚动直线导轨副综合性能测试试验台的加载系统。     

Multi-objective optimization of rolling schedule based on cost function for tandem cold mill

In terms of tandem cold mill productivity and product quality, a multi-objective optimization model of rolling schedule based on cost fimction was proposed to determine the stand reductions, inter-stand tensions and rolling speeds for a specified product. The proposed schedule optimization model consists of several single cost fi.mctions, which take rolling force, motor power, inter-stand tension and stand reduction into consideration. The cost function, which can evaluate how far the rolling parameters are from the ideal values, was minimized using the Nelder-Mead simplex method. The proposed rolling schedule optimization method has been applied successfully to the 5-stand tandem cold mill in Tangsteel, and the results from a case study show that the proposed method is superior to those based on empirical formulae.     

Numerical simulation and model of control-efficiency of thermal crown of work rolls in cold rolling

Aiming at accuracy control of the thermal crown of work rolls in cold rolling, new parameters such as regulation domain and control-efficiency factors were proposed and a numerical analysis model of the thermal crown of work rolls was established using finite difference method to study roll＇s thermal deformation. Based on simulation results, the influences of control-efficiency factors on thermal crown are presented and the thermal crown of work rolls is analyzed after taking sub-cooling of sprinkling beam into consideration. It has been found that the control-efficiency factor of any position on the roll＇s surface is linear function of the temperature and the control ability of water temperature is stronger than other control parameters. In addition, the verification of the model has been carried out based on the producing technology data in some factories and the numerical simulation results coincide well with the experimental data. Therefore, this work has important value for on-line control of roll＇s crown in cold rolling.