磨料有序排布电镀砂轮的制备及其把持力研究

为解决电镀砂轮磨削加工中容屑空间不足的问题，采用点胶微粘接的方法制备了磨料有序排布的电镀砂轮，分析了磨料粘接效果和镀层力学性能。通过SEM分析了磨料/镀层/导电胶的结合界面，并进行了干磨削试验。研究结果表明，直径约为磨料粒径40%的胶点可粘接住磨料，单个胶点上粘接多颗磨料的占比小于6%；双脉冲电镀工艺制备的镀层显微硬度大于500HV，表层残余应力小于100MPa，磨料/镀层/导电胶之间的界面贴合紧密，无明显缺陷；砂轮在磨削时没有出现磨料脱落现象。     

组合轮径差对地铁车辆动力学性能的影响

为了研究各种轮径差组合形式对地铁车辆动力学性能的影响,基于车辆系统动力学和赫兹非线性接触理论,建立地铁动车非线性动力学模型,分析各种轮径差组合工况下地铁车辆的临界速度、平稳性、安全性和磨耗功率及其变化规律。结果表明:在多种轮径差组合工况下,轮径差增大会使地铁车辆的临界速度有较大幅度降低,会使地铁车辆的横向平稳性和磨耗功率明显增大;轮径差对地铁车辆的垂向平稳性、轮轴横向力、轮轨垂向力、脱轨系数和轮重减载率影响较小;通过左、右曲线时,轮径差对磨耗功率增幅的影响存在差异,但变化规律一致。     

新型胶轮机车运行方式在大坡度盾构隧道施工中的应用

在传统地铁隧道施工中,有轨机车为主要运输方式,近年来有少量项目采用多功能胶轮机车运送施工材料。本文依托莫斯科地铁第三换乘环线东段大直径盾构项目案例,介绍胶轮机车的结构特点、使用优势、弧面运行时的轮胎保护措施。实践证明,胶轮机车在地铁隧道施工中具有很好的技术经济性,改进后的运行方式使其在管片弧面运行时性能更稳定。     

四轮轮毂电机驱动电动汽车电液复合制动平顺性控制策略

液压制动与电机再生制动的时域响应差异导致电动汽车在制动模式切换时产生冲击感，影响驾驶员驾驶感受和乘坐舒适性。以四轮轮毂电机驱动电动汽车为研究对象，提出一种基于分层架构的电液复合制动平顺性控制策略。针对"高压蓄能器+电机泵"式电子液压制动系统（EHB），上层控制器提出基于模糊控制的轮缸压力控制策略；针对制动模式切换过程中产生的冲击，下层控制器提出包括液压介入预测模块和电机制动补偿模块的电液复合制动平顺性控制策略。通过Simulink-AMESim联合仿真平台进行仿真试验验证。结果表明，轮缸压力控制策略能够保证轮缸液压力较好地追随目标压力，且稳态误差不超过2%；电液复合制动平顺性控制策略能够有效提高制动系统的响应速度，同时显著降低制动模式切换时的冲击，能提升车辆制动平顺性和乘坐舒适性。     

The barrel aged beer wheel: a tool for sensory assessment

There has been an increasing interest in the wooden barrel aging of beer in breweries worldwide. Monitoring of the barrel aging process relies mostly on changes in sensory parameters over time. This may be difficult for teams or brewers with little or no appropriate experience. The beer sensory wheel presents a broad approach to sensory aspects and generalised attributes for many beer styles. Accordingly, this tool may result in confusion through excessive visual information. The work reported here is based on literature research and sensory panel analysis employing ultra-flash profile with the aim to build a new visual tool for wooden barrel aged beer. This will aid the evaluation, training and quality assessment of barrel aged beer. It also provides specific terminology to describe the sensory changes during the barrel aging process. This approach was used to elucidate the characteristics of different wood species (amburana, cabreúva and American oak), and evaluate the flavour transformation of wooden barrel aged beer compared to non-aged beer. The barrel aged beer wheel comprises attributes and references for flavour evaluation and also terms that define the main transformational pathways, namely oxidation, wood extraction and biotransformation. The wheel described here is intended to meet academic and professional needs for the quality assessment of wooden barrel aged beer based on sensory analysis. © 2020 The Institute of Brewing & Distilling     

低比转速压气机轮毂轮缘型线多目标优化设计

对电动增压器用低比转速离心压气机轮毂轮缘进行优化设计。采用NUMECA/FINE Design 3D对压气机进行几何参数化,生成数据库样本,利用人工神经网络和遗传算法对轮毂轮缘型线进行优化,并进行流场分析。仿真结果表明,在设计转速为40000 r/min时,优化后设计点压比和效率分别提高6.59%和3.73%。     

改进ILoG算子的故障检测方法

针对强背景噪声干扰下轮对轴承故障特征微弱、难以准确检测的问题,提出了一种自适应改进高斯拉普拉斯(improved Laplacian of Gaussian,简称ILoG)算子的微弱故障检测方法。ILoG算子滤波器具有优良的信号突变特征检测能力,将其用于轮对轴承故障信号的冲击特征检测,同时利用水循环算法(water cycle algorithm,简称WCA)的寻优特性,并行搜寻筛选最佳的ILoG算子影响参数,通过对参数优化后ILoG算子滤波后信号做进一步包络解调分析,提取出轮对轴承微弱的故障特征信息。对实际轮对轴承外圈和内圈故障信号分析的结果表明,该方法可以有效检测出轴承微弱故障特征频率,故障检测效果优于小波阈值和多尺度形态学差值滤波方法。     

M1080B无心外圆磨床改进

M1080B无心外圆磨床砂轮及导轮宽度较窄,磨削轴承套圈外圆时,磨削效率低,托板架调整较为繁琐、皮带打滑、磨损较为严重。针对上述问题,提出了相应的解决办法,提高了磨削效率。     

Experiment and Simulation of Metal Flow in Multi-stage Forming Process of Railway Wheel

To investigate the metal flow during the railway wheel forming process,experiments and finite element method(FEM)simulation were carried out.An axisymmetric modeling for the wheel rolling process was proposed to predict the metal flow in radial direction,by which the whole multi-stage forming process could be simulated in axisymmetric and integral way.The result shows that the axisymmetric simulation method was an effective method to explore the metal flow in radial direction and to analyze the relationships of tools motion during the wheel rolling.The detail information about metal flow in railway wheel forming process was obtained.The metal in the wheel web was from the area near the half radius of the original billet;the chill zone of the billet became an envelope of the rim and part of the web with a maximum thickness of about 6mm below the tread.At the wheel rolling stage,the metal in the rim flowed towards the web;the metal near the surfaces of the conjunction region between the web and rim suffered severe shear deformation.     

Effect of grinding-induced cyclic heating on the hardened layer generation in the plunge grinding of a cylindrical component

This paper discusses the effects of the grinding-induced cyclic heating on the properties of the hardened layer in a plunge cylindrical grinding process on the high strength steel EN26. It was found that a multi-pass grinding brings about a uniform and continuous hardened layer along the circumference of the cylindrical workpiece. An increase of the number of grinding passes, leads to a thicker layer of hardening, a larger compressive residual stress and a deeper plastic deformation zone. Within the plastic deformation zone, the martensitic grains are refined by the thermo-mechanical loading, giving rise to a hardness of 12.5% higher than that from a conventional martensitic transformation. The coupled effects of heat accumulation and wheel wear in the multi-pass grinding are the main causes for the thickening of the hardened layer. A too small infeed per workpiece revolution would result in insufficient grinding heat, and in turn, bring about an undesirable tempered hardened layer and a reduction of its hardness.