装配尺寸链在托辊装配中的应用

托辊在加工和装配过程中很难保证轴承内圈与中心轴配合,轴承外圈与轴承座配合,两端压盖与辊筒端面紧密帖合。通过对托辊原结构进行分析与改进,可简化加工难度和装配难度,并对改进后的结构进行尺寸链计算,合理分配各零件的极限偏差,既降低了生产成本,又满足了使用要求。     

大尺寸玻化地砖铺装质量控制初探

文章就大尺寸玻化地砖铺贴后出现空鼓、起拱现象的原因进行了分析,并指出应从设计、地砖质量、施工方法方面采取相应的措施加以控制。     

SWRM6盘条断裂原因分析

某条材厂生产SWRM6盘条时,在拉拔过程中出现异常断裂。通过宏观观察、扫描电镜及金相显微镜对断裂试样进行了深入分析,结果表明,盘条的脆性断裂与组织中的铁素体晶粒粗大及晶界析出的渗碳体密切相关,因此,应当通过适当降低相关工艺温度,以及冷却时尽量避开有害温度区间等措施解决。     

螺纹切削加工指令在数控车床上的应用

本文是通过螺纹的尺寸分析、刀具的装刀与对刀和普通螺纹的编程指令几个方面阐述了螺纹加工指令在数控车床上的应用.     

Formation mechanism and size prediction of bubble in opposite-flowing T-shaped microchannel

Bubble formation in an opposite-flowing T-shaped microchannel with 40 μm in depth and 120 μm in width was real-time visualized and investigated experimentally by means of a high speed camera. N2 bubbles were generated in glycerol-water mixtures with different concentrations of surfactant sodium dodecyl sulfate (SDS). And the images were captured by the high speed camera linked to a computer. Results indicated that the bubble formation process can be distinguished into three consecutive stages, i.e., expansion, collapse and pinching off. The bubble size decreases with the increase of liquid flow rate and viscosity of liquid phase as well as the decrease of gas flow rate. The surface tension of the liquid phase has no measurable influence on the bubble size. Moreover, a new approach to predicting the size of bubbles formed in the T-shaped microchannel is proposed. And the predicted values agree well with the experimental data.     

Vibration shape testing of space sheet structure

The space sheet for a solar array structure is large in dimension, and flexible to induce complex distortion. It is difficult to measure the distortion. A large-scale flexible test prototype system is built for sheet structure vibration monitoring based on the vibration information of the solar array in space. The system provides an intelligent test method for flexible space structure with embedded sensors and non-visualization reinstruction. Multiple fiber Bragg grating （FBG） sensors are packaged and embedded into the structure with spatial division multiplexing （SDM） and wavelength division multiplexing （WDM）. The sensor interrogator distinguishes wavelength shifts that can be turned into curvature of the curve. The structure shape is reconstructed based on the curvature information and the arc-length, and then displayed. The experiment shows that the system has a high FBG sensitivity. The reconstruction algorithm is fast with high precision. The system has great potential for use in health monitoring of the space sheet structure.     

截面尺寸对玻璃纤维包裹加固砖柱效果的影响

为研究截面尺寸对玻璃纤维加固砖柱轴压性能的影响,进行了39个(13组)不同截面尺寸的砖砌体柱经玻璃纤维增强材料全长包裹加固后的轴心受压试验,分析了试件截面尺寸、砂浆强度以及黏贴层数等因素对加固后试件极限强度的影响.试验结果表明:这种加固方式能不同程度提高砖柱的极限承载力,极限强度随加固层数线性变化.参照FRP加固混凝土柱的基本原理,建立了FRP加固砖柱的有效约束区与非有效约束区.     

固体材料导热系数的分子动力学模拟

采用分子动力学方法对金属和非金属材料薄膜的导热系数进行数值模拟. 非金属材料氩的粒子间相互作用势采用12/6 L-J势能模型,金属材料钨使用MEAM势能模型. 模拟结果表明,非金属材料氩的导热系数与已有实验结果符合较好,但金属材料钨的导热系数结果较实验结果小1~2个数量级. 研究结果表明,引入自由电子导热模型能较准确预测金属材料钨的导热系数变化规律.     

作图法求解形位公差和尺寸公差相互补偿关系

国家标准《公差原则》确定了形位公差和尺寸公差之间的关系。传统的方法是采用动态公差图来求解对应关系,但求解方法不够直观、形象。采用作图法求解尺寸公差和形位公差的相互补偿关系,能简洁、直观地得出结果。