某双列圆柱滚子轴承的加工难点与解决方法

某双列圆柱滚子轴承的某些工序加工难度较高,例如,保持架铆合时必须用铆钉全部填满铆合孔;铆合后磨削两端面时其内部不能进入冷却液。通过反复实验,对铆钉结构进行了改进,设计了两套磨削密封辅具,解决了存在的问题,达到了技术要求,保证了生产的顺利进行。     

某圆锥滚子轴承异音故障分析

一批圆锥滚子轴承32313装机使用后,产生很大的振动和噪声。经拆套分析发现,故障是由于滚子磨伤引起的。提出了避免磨伤的相应措施,使振动和噪声恢复到合格范围。     

横琴口岸工程ST-100塔式模架支撑体系应用技术

结合工程实例进行研究分析,针对ST-100塔式模架支撑体系,对比扣件式钢管脚手架和承插式盘扣脚手架,研究分析S T-100塔式模架支撑体系的优势。并结合高大模板施工技术,详细探讨和研究S T-100塔式模架支撑体系在其中的应用。总结的技术和经验可供类似工程借鉴。     

Modeling and Optimization of Nanofluid Flow in Flat Tubes Using a Combination of CFD and Response Surface Methodology

In this paper, modeling and optimization of Al₂O₃–water nanofluid flow in horizontal flat tubes is performed using a combination of computational fluid dynamics (CFD) and response surface methodology (RSM). At first, nanofluid flow is solved numerically in various flat tubes using CFD techniques and the heat transfer coefficient () and pressure drop () in tubes are calculated. The numerical simulations are performed using two phase mixture model by FORTRAN programming language. The flow regime and the wall boundary conditions are assumed to be laminar and constant heat flux respectively. In the second step, numerical data of the previous step will be used for a parametric study, modeling and optimization of nanofluid flow in flat tubes using the RSM technique.It is shown that the results include important design information on nanofluid parameters in flat tubes. The important design information about the relationship between design variables and responses will not be achieved without the simultaneous use of CFD and optimization approaches.     

激光微织构滚动轴承表面润滑性能的数值分析

目的研究圆柱滚子轴承摩擦副织构化表面润滑性能,探讨工况参数(载荷、转速)和微织构几何形貌参数(面积占有率)对油膜平均无量纲压力的影响规律。方法基于弹性流体动压润滑机理,利用有限长线接触弹流润滑理论建立理论模型,采用有限差分法对Reynolds方程进行离散,并运用多重网格法进行数值分析。结果在微织构面积占有率S_p=0.095、深度h_p=6μm的前提下,当载荷由100 N升为500 N时,油膜平均无量纲压力随之增大。在微织构面积占有率S_p=0.095、深度h_p=6μm的前提下,当转速由100 r/min升为500 r/min时,油膜平均无量纲压力随之增大。在载荷W=200 N、转速n=200 r/min的前提下,当微织构面积占有率由0.05升为0.15时,油膜平均无量纲压力随之增大;当微织构面积占有率由0.15升为0.25时,油膜平均无量纲压力随之减小。结论圆柱滚子轴承微织构表面的油膜平均无量纲压力随着载荷和转速的增大而增大,随着微织构面积占有率的增大而先增大后减小。     

二十辊森吉米尔轧机辊系稳定性的有限元分析

应用ABAQUS有限元软件建立了二十辊轧机有限元分析模型,研究了不同辊径配置及不同轧制力工况对二十辊森吉米尔轧机辊系稳定性的影响。结果表明:第1中间辊辊径差不小于2mm时,第1中间辊和第2中间辊被挤出;第2中间辊辊径差不小于4mm时,辊系失稳散落;第2中间随动辊比驱动辊小,会使第1中间辊辊间距变小,并使第2中间驱动辊与B、C支撑辊接触点的应力变小。随着轧制力的增大,第1中间辊的辊间距增大,第2中间驱动辊与B、C支撑辊接触点处的应力也增大。     

基于故障树的采煤机液压盘式制动器故障研究

通过逻辑分析构建了采煤机液压盘式制动器故障与基本事件的故障树模型;采用二元决策图分析故障树模型,得到了导致制动器故障发生的最小割集,并通过状态枚举法计算了基本事件的结构重要度。结果表明,所列举的任一基本事件的失效均会导致制动器故障。为采煤机液压盘式制动器的故障诊断提供了理论依据。     

基于ANSYS的采煤机摇臂双列圆锥滚子轴承配合精度分析

分析了采煤机摇臂行星机构的结构组成,对采煤机摇臂行星机构的受力情况进行了分析,阐述了双列圆锥滚子轴承内外圈配合精度的选择方法。通过建立三维模型,在ANSYS软件中对比分析了H7/k6和H7/m6配合精度下采煤机摇臂行星机构的刚性数据,得出了摇臂行星机构双列圆锥滚子轴承内圈更适宜采用H7/m6配合精度的结果。     

辊磨液压系统选型及工况探讨

介绍了VRMR360.4辊磨的液压系统蓄能器的计算方法,对有杆腔蓄能器容积和无杆腔蓄能器容积进行了选型计算,通过分析不同的工况,选取合适的工作参数。     

Preparation of hydrophobic flat sheet membranes from PVDF-HFP copolymer for enhancing the oxygen permeance in nitrogen/oxygen gas mixture

In this study, poly(vinilydene fluoride-co-hexafluoropropylene)(PVDF-HFP) was used for preparation of hydrophobic membranes using non-solvent induced phase inversion(NIPS) technique. PVDF-HFP copolymer with concentrations of 10 wt% and 12 wt% was prepared to investigate the effect of polymer concentration on pore structure,morphology, hydrophobicity and performance of prepared membranes. Besides, the use of two coagulation baths with the effects of parameters such as coagulant time, polymer type and concentration, and the amount of nonsolvent were studied. The performance of prepared membranes was evaluated based on the permeability and selectivity of oxygen and nitrogen from a gas mixture of nitrogen/oxygen under operating conditions of feed flow rate(1–5 L·min~(-1)), inlet pressure to membrane module(0.1–0.5 MPa) and temperatures between 25 and 45 °C. The results showed that the use of two coagulation baths with different compositions of distillated water and isopropanol,coagulant time, polymer type and concentration, and the amount of non-solvent additive have the most effect on pore structure, morphology, thickness, roughness and crystallinity of fabricated membranes. Porosity ranges for the three fabricated membranes were determined, where the maximum porosity was 73.889% and the minimum value was 56.837%. Also, the maximum and minimum average thicknesses of membrane were 320.85 μm and115 μm. Besides, the values of 4.7504 × 10~(-7) mol· m~(-2)· s~(-1)· Pa~(-1), 0.525 and 902.126 nm were achieved for maximum oxygen permeance, O_2/N_2 selectivity and roughness, respectively.