基于振动信号的深沟球轴承滚动体故障诊断研究

目前针对滚动轴承内、外圈故障的诊断方法较为有效,但难以诊断滚动体故障。针对这种情况,利用时域统计参数(有效值、峭度、脉冲因数、裕度因数)与Hilbert包络谱两种方法,对不同转速、负荷和故障程度情况下滚动体故障与正常状况的振动加速度数据进行比较分析,得出了滚动体故障难以诊断的原因,并给出了解决方法。     

插针焊线槽成形工艺优化及模具设计改进

针对某插针焊线槽成形后存在的偏心、翘头等问题,通过成形工艺、模具设计两方面进行了原因分析,介绍了优化、改进后的焊线槽成形工艺及模具设计.     

无油沟圆柱滚子轴承滚道及挡边磨加工方法

在介绍圆柱滚子轴承滚道无油沟套圈的磨削加工方法的过程中,重点阐述了在3M1420沟道磨床中采用成形切入磨削方法及砂轮修整时的改进方案。实践证明,采用成形切入磨削的加工方法,能够实现无油沟滚道的加工。     

彼德斯重介质分选槽常见故障及其改进

介绍了彼德斯重介质分选槽的结构和工作原理及其在我国的应用情况，总结了重介质分选槽常见的各种故障，提出了解决各种故障的改进方法，降低了故障率，方便了检修，以及该项设备今后的发展方向与发展建议。     

沟槽结构对水润滑轴承润滑特性影响机制

为了研究沟槽结构对船用水润滑轴承润滑特性的影响机制，采用有限元法，通过对简化后的椭圆形沟槽的二维模型进行流体动力学CFD分析，从迹线以及涡流等方面分析沟槽结构参数对沟槽内部流体特征的影响，得到不同状态下沟槽内部的压力轮廓，并分析沟槽结构参数对水润滑轴承摩擦因数的影响和轴承的润滑机制。结果表明：沟槽的大小影响轴承间隙内流体的流通面积，沟槽的结构特征影响沟槽内的流体黏度。研究结果可为水润滑轴承优化设计提供参考。     

Enhanced electromagnetic transmission through a slit surrounded by rectangular grooves

Electromagnetic transmission through a slit surrounded by rectangular grooves in a conducting plane is investigated. An electromagnetic boundary-value problem associated with a slit surrounded by rectangular grooves in a conducting plane is rigorously solved based on the Fourier transform, eigenfunction expansion and mode matching method. The transmission coefficient through the slit is represented in a series. Computation is performed to illustrate the effect of the groove geometry on the transmission behaviours.     

Study of the geometry of a voided clay brick using non-rectangular perforations to optimise its thermal properties

This study seeks to improve the geometrical distribution of bricks to optimise the equivalent thermal transmittance of a wall built of Termoarcilla^® ECO 29 voided clay bricks, using calculations according to Spanish UNE [1], AENOR [10], European EN [6], [7], [8] and [9] and international ISO [11] and [12] standards.The objective is to study improvements in the wall's thermal conductivity, always remembering the limitations imposed by the manufacturing process. Simulations are made using a finite elements application [14].It is concluded that, within the possibilities allowed by the manufacturing process, with non-rectangular voids the heat flux has to cross a higher number of voids, which improves its thermal properties. A rhomboid layout of voids with the longer diagonal at right angles to the heat flux is the best internal void layout. If the internal perforations are also extended to the end of the tongue and groove, the direct thermal bridge in this type of brick is broken.Finally, a 290 mm wide brick with 25 rows is obtained with the geometrical properties described above which shows an improvement of almost 16% over the original ECO 29 brick, performing well in all climatic areas of Spain, with a full-bed mortar joint 30 mm thick.     

Microstructure–mechanical property relationship in an Al–Mg alloy processed by constrained groove pressing-cross route

The constrained groove pressing-cross route process was implemented on a commercially annealed AA5052 alloy at room temperature, with up to two passes (strain of ～4.64) along the rolling direction and transverse direction. The results showed the formation of an ultrafine-grained structure with an average sub-grain/cell size in the 300–500?nm range. The indentation hardness and tensile strength increased significantly, up to ～75 and 105%, respectively, and became more homogenous with a uniform and isotropic trend, as compared to the annealed alloy. According to the Hall–Petch and Taylor models used, grain refinement and increasing dislocation density were proposed as the main strengthening mechanisms. Fractographic studies revealed a ductile-fracture behaviour, with a dimpled structure proportional to the UFG structure.     

干气密封的流动数值模拟

在探讨干气密封工作原理的基础上提出了利用流动数值模拟进行干气密封端面设计的一种新方法，即选用三维的纳维一斯托克斯方程作为控制方程，用改进的压力偶联方程组半隐式方法(SIMPLER算法)对方程组进行离散，对干气密封摩擦副之间的气体流动进行了数值模拟。利用该方法不仅求得了计算域内的压力分布，而且还求得了速度分布。计算结果表明，干气密封的开槽区域的密封堰对气体产生泵送作用，增大了密封槽内气体的压力，大大增强了干气密封的开启效应，而密封坝对气体流动起到节制作用。对计算结果进行分析，求得了干气密封的工作点和泄漏量，计算泄漏量与实测值很吻合，相对误差不超过10％，与常用的二维计算方法相比，可得到更为精确的结果，为进行干气密封端面二维、三维沟槽结构的优化设计提供了正确、可靠的理论依据。     

管板孔不同开槽宽度对胀接接头拉脱力的影响

随着计算机技术的快速发展,CAE技术也越来越多的应用到工程技术领域。采用计算机有限元技术,在对换热器管板在开槽宽度不同情况下,对液压胀接接头拉脱力的有限元进行模拟分析。使用ANSYS软件进行三维建模,并施加载荷及边界约束条件进行模拟计算。根据理论设计参数进行实验,将实验结果与有限元模拟结果进行比较,结果发现:拉脱过程中支反力最大值发生在拉脱起始阶段,开槽宽度越大,拉脱力越大;当开槽宽度小于6mm时,理论与实验结果非常接近;当开槽宽度大于6mm时,理论与实验结果随宽度增大而相差越大,主要是由于管子和槽边缘之间的严重的“刮蹭”引起的。