Concentric Annular Clearance-Controllable Pressure Characteristics Research of a High Pressure Pneumatic Pressure Assembly

High pressure is an important development orientation in pneumatic field,since it can not only improve dynamic characteristics of pneumatic system but also decrease the size of components and mounting space.Due to the advantages of high energy density and high instant expansibility,high pressure gas has been widely used in many applications.However,systematic researches are lacked especially in pressure characteristics which are very important in pneumatic system at present.In a high pressure pneumatic system,the pressure of a fixed cavity with annular clearance needs to be controlled within a wide range,so a single stage proportional slide valve is proposed to satisfy the requirements of high pressure and low flow rate.First,working principle and structure of the pressure assembly and the slide valve are introduced.Then mathematical model of the high pressure pneumatic system is built up;controllable pressure range is simulated,and influence of uncertain factors,such as fit clearance of the pressure valve and the cavity on controllable pressure,is discussed.Finally,a test bench of the pressure assembly is built up,and the controllable pressure and step response experiments are carried out.Both simulation and experimental results show that the designed slide valve can satisfy the requirements well.The proposed clearance presumption method based on simulation and experimental results is valuable for indirect measurement of processing tolerance.     

含间隙卫星天线双轴机构动态磨损特性研究

卫星天线双轴驱动机构是天线系统实现精确定位的关键组件,磨损间隙是影响天线指向精度及寿命的主要因素.采用非线性弹簧阻尼模型建立了间隙处的接触碰撞模型,同时采用Coulomb摩擦模型考虑运动副间隙处的摩擦作用,进而建立了含间隙双轴机构的动力学模型,对其进行动力学仿真,提取出接触碰撞时的动力学参数,基于Archard's摩损模型计算运动副间隙的动态磨损量,从而得到间隙运动副的动态磨损特性,为进一步研究非规则时变间隙对卫星天线系统动态性能的影响提供基础.     

彩钢板成型机冲裁机构刀具动态仿真与工艺优化

优化彩钢板成型机冲裁机构刀具的冲裁工艺,减小在冲裁薄件时刀具的冲裁力,延长刀具使用寿命,提高冲裁质量.对刀具不同凹刃口的倾斜角度和上下刀具纵向的不同间隙分别进行动态有限元模拟.通过动态有限元仿真结果得出,凹刃口的倾斜角度在4～5°之间较为合适,刀具的纵向合理间隙应为板材厚度的7％左右,有利于实现减小刀具的冲裁力,延长模...     

±500 kV同塔双回线路杆塔空气间隙操作冲击放电特性试验研究

在海拔2 100 m和50 m地区对±500 kV同塔双回线路杆塔空气间隙的操作冲击放电特性进行试验研究,在实验条件下,获得了上、下层间隙的50%放电电压曲线,验证了下横担的存在对上层空气间隙的操作冲击放电特性无明显影响。基于两种海拔高度试验结果对比,提出了海拔2 100 m及以下地区的海拔校正方法和校正系数,进而给出了当操作过电压标幺值取1.6时,不同海拔高度下所要求的杆塔上、下层空气间隙的最小允许距离。成果已用于指导溪洛渡右岸电站送电广东±500 kV同塔双回直流输电工程的外绝缘设计。     

离心式空气压缩机隔板中分面内漏面积的模型建立及拟态检测

介绍了催化裂化装置能量回收机组中重要设备MCL型离心式空压机隔板中分面冲蚀间隙面积的计算模型,以及使用激光对中仪对隔板中分面选取点位进行数据拟态检测的方法,为压缩机气体内漏原因的筛查和修复提供了依据.     

汽轮机叶顶间隙泄漏流动的数值研究

采用κ-wsst湍流模型,应用SIMPLEC算法对汽轮机叶顶间隙内的泄漏流动进行数值模拟,分析了叶顶间隙泄漏流动对叶顶静压分布、吸力面压力分布、湍动能和叶片表面压力系数的影响.由于叶顶间隙的存在,间隙泄漏流使叶顶静压分布产生波动,在叶片吸力面靠近叶顶处出现低压区,且造成叶片表面压力系数降低.随着间隙高度的增加,上述特征...     

Design rules for suspending concentrated mixtures of solids in stirred tanks

This study examines complete off-bottom suspension conditions for slurries containing mixtures of solids at a wide range of concentrations. Binary combinations of five different particles; bronze, two sizes of glass beads, ion exchange resin, and nickel were tested with two impellers: the Lightnin A310 and the down pumping 45° PBT. The effect of particle size ratio and density ratio of the two solid phases on N_js was investigated. Solids loadings were varied from 3 to 56 wt% (weight percent) with water as the liquid phase. The results showed that the highest particle N_js in a mixture of solids is not a sufficient design specification to ensure suspension of the mixture. For one of the cases studied, the particle–particle interactions became significant at high loadings and resulted in a decrease in N_js. Different behaviours were observed for the other mixtures. The performance of the two impellers was also compared. The A310 impeller consumes significantly less power at N_js than the PBT. Both impellers showed an effect of off-bottom clearance on N_js, but the effect of off-bottom clearance depended on both the solids concentration and on the solids used.     

基于雅可比旋量法的实际工况公差建模

计算了加载时工作零件的变形量,并将其转变为雅可比旋量修正量,通过对雅可比旋量公差模型在实际工况下的扩充与修正,建立了基于雅可比旋量和实际工况的装配体公差数学模型,以此定量计算实际工况对产品工作性能及公差设计的影响。通过将此方法在某齿轮泵装配体的公差设计中的应用说明了该方法的有效性。     

基于滚动轴承游隙调整与预紧的研究

机械设备在使用过程中,经常由于滚动轴承游隙调整与预紧不合适,造成设备运转精度降低、轴承损坏,严重的甚至会发生安全事故。笔者介绍了调整与检测滚动轴承游隙的方法,分析了影响游隙调整的因素,对装配维修人员具有一定的借鉴作用。     

滚切式定尺剪剪刃间隙调整的研究

介绍滚切式定尺剪剪刃间隙的调整方法,结构问题及改进。