高强度螺栓扭矩系数影响因素的实验研究

高强度螺栓广泛地应用于工程领域,扭矩系数是评定其性能级别的重要参数.本文讨论了扭矩系数的影响因素;在理论分析的基础上,通过实验方法研究各种因素对扭矩系数的影响规律;介绍了该研究结果在高强度螺栓联接件的制造、检验及工程质量控制方面的实际应用.     

钢结构用摩擦型高强度螺栓连接副的设计与施工

通过对钢结构用摩擦型高强度螺栓连接副应用的详细分析,阐述了螺栓数量与连接板的计算,高强度螺栓的预紧力,扭矩系数K与施工扭矩的确定与检验,施工环境温度对扭矩系数K影响的经验公式,连接面的表面处理与抗滑移系数的关系,抗滑移系数的试验与数据处理,连接头的验算,高强度螺栓连接副施工中常见问题的处理方法,以及螺栓副相关参数快速计算的方法。对设计与施工技术人员正确使用高强度螺栓连接副具有指导作用。     

螺纹紧固件扭矩系数的实测比较与分析

采用扭矩系数法拧紧高强度螺栓时,扭矩系数平均值和扭矩系数标准偏差对紧固效果的影响很大。除理论计算外,扭矩系数亦可实测获得。本文在实验的基础上分析实测扭矩系数,讨论不同实验条件与相应扭矩系数之间的关系,比较各种旋合材料的扭矩系数之差异,评析扭矩系数和标准偏差对连接可靠性的影响,浅议高强度紧固件的再次使用问题。     

大直径高强度螺栓联接扭矩系数与润滑的关系

大直径高强度螺栓联接扭矩系数与润滑的关系北京起重运输机械研究所张维钧大直径高强度螺栓如Ｍ２７、Ｍ３０螺栓联接副，用于特大跨度重型钢结构及其它传递重载荷的场合，如大型涨盘联接件等。准确的测定高强度螺栓预紧力的扭矩系数与其润滑因素的关系具有实际意义。螺栓...     

高强度螺栓预拉力与滑移系数实验研究

本文报道了对高强度螺栓连接副进行预拉力实验与对高强度螺栓连接母材进行抗滑移实验的结果。得出了高强度螺栓的预拉力、扭矩系数、抗滑移系数等。对实验结果进行分析讨论。     

高强度螺栓预拉力与滑移系数实验研究

本文报道了对高强度螺栓连接副进行预拉力实验与对高强度螺栓连接母材进行抗滑移实验的结果.得出了高强度螺栓的预拉力、扭矩系数、抗滑移系数等.对实验结果进行分析讨论.     

摩擦系数对微车高强度螺栓联接性能的影响研究

针对目前大多汽车厂商没有控制螺栓的摩擦系数,联接可靠性差的问题,通过对控制摩擦系数前后的微车常用的电镀锌高强度螺栓进行拧紧实验和不同摩擦系数的螺栓进行横向振动实验,并从控制扭矩系数稳定性、扭矩转化率、防松脱等方面分析了摩擦系数对螺栓联接性能的影响。结果表明:随着摩擦系数的散差减小,扭矩系数的散差减小;随着摩擦系数的增大,螺栓的防松性能越好,但是扭矩转化率越低。控制螺栓的摩擦系数能控制扭矩系数的稳定性,提高摩擦防松的稳定性。     

高强度螺栓—新型的钢结构连接件

介绍高强度螺栓连接副元件的材质与性能，影响高强度螺栓预拉力的因素及与扭矩系数的关系，被连接件表面的处理方法，连接接关头的构造及影响承载力的因素。     

轨道车用高强度螺栓扭矩系数试验研究

轨道车在高速运行过程中,轮盘螺栓连接强度影响行车安全,准确控制轮盘螺栓的轴向力是提高轨道车安全运行系数的有效途径之一。研究了影响螺栓轴向力的扭矩系数,实测了相同扭矩及安装条件下,不同螺纹副表面处理下螺栓的扭矩系数,可为螺栓的安装提供一定的工艺参考。     

表面处理对钢结构用高强度螺栓连接副扭矩系数的影响

钢结构用高强度螺栓连接副扭矩系数的检验是该产品技术条件中必须检验的项目之一。由于高强度螺栓连接副主要用于铁路、工路桥梁、锅炉钢结构、工业厂房、高层民用建筑、塔桅结构、起重机械等一些较为重要的设施和场所中，所以钢结构用高强度螺栓连接副的各项技术要求相对来说都比较严格，而连接副扭矩系数是否合格，则直接关系到整体钢结构连接的成功与否，     

一种表面结构多尺度融合测量系统

提出了一种表面结构多尺度融合测量系统,该系统将显微图像测量、垂直扫描白光干涉测量、白光干涉纳米探针测量和白光干涉金刚石探针测量等多种不同尺度的表面结构测量方法融合在一起。实验结果表明,显微图像测量对300μm标准玻璃线纹尺的示值误差为-0.251μm,标准偏差为0.4013μm;白光干涉测量对1.26μm和3.33μm单刻线样板的测量平均值分别为1.263μm 和3.328μm,示值误差分别为0.003μm和 -0.002μm,示值相对变化量为1.27%和0.63%;白光干涉纳米探针对高度为（106.8±1.0）nm的校准光栅测量平均值为103.1nm,相对示值误差为-3.5%;白光干涉金刚石探针测量对Ra=4.08μm样板的测量值为4.05μm,测得值的相对误差为0.74％。所提出的测量系统满足表面结构的多尺度融合测量要求。     

Surface morphology and interdiffusion of LiF in Alq3-based organic light-emitting devices

Highly efficient organic light-emitting devices (OLEDs) have been realized by insertion of a thin insulating lithium fluoride (LiF) layer between aluminum (Al) cathode and an electron transport layer, tris-(8-hydroxyquinoline) aluminum (Alq₃). In this paper, we study the surface morphology of LiF on Alq₃ by synchrotron X-ray scattering and atomic force microscopy (AFM) as a function of thickness of LiF. We also study the interdiffusion of LiF into Al cathode as well as into Alq₃ layer as a function of temperature. Initially, LiF molecules are distributed randomly as clusters on the Alq₃ layer and then gradually form a layer as increasing LiF thickness. The interdiffusion of LiF into Al occurs more actively than into Alq₃ in annealing process. LiF on Alq₃ induces the ordering of Al to (1 1 1) direction strongly with increasing LiF thickness.     

The application of high resolution electron microscopy to the study of oxidation

High resolution electron microscopy has been used to examine both the similarities and differences in the growth morphologies of Fe₂O₃, Cr₂O₃ as formed on iron alloys, and MgO as formed by burning Mg in moist air. A general discussion is also given of the relative advantages and disadvantages of a variety of TEM techniques as applicable to the study of oxidation phenomena.     

Resonant frequency characterization of MEMS based energy harvesters by harmonic sampling analysis method

This paper presents a new and accurate experimental method based on harmonic distortion analysis to determine the resonant frequency of MEMS devices to be used as energy scavengers or more generally in widespread MEMS-based applications. This technique uses the mechanical–electrical analogy of MEMS variable capacitor acting as a low-pass filter to give access to both resonant frequency and damping factor of the mechanical system through the determination of the filter parameters as the cut-off frequency. Resonant frequencies ranging from 0.8 kHz to 5 kHz of electrostatic actuated MEMS-based harvesters have been measured by this technique with an uncertainty as low as a few parts in 10³ in a good agreement with measurements carried out by using Deep Level Transient Spectroscopy system.     

Cram be abyssinica oil and its derivatives as renewable lubricants: Synthesis and characterisation of different esters based on crambe fatty acids

The authors have studied the possibility of using Crambe abyssinica oil as a starting material for synthetic lubricants, and in this paper the procedures for the preparation of monoesters from methyl, ethyl, isopropyl, and 2-ethylhexyl alcohol, as well as diesters from neopentylglycol, triesters from trimethylolpropane and tetraesters from pentaerythritol, are described. The different reactions were set up using free fatty acids, methyl esters, and Crambe oil as starting materials. All reactions were carried out in a solvent-free medium, using normally available catalysts and under experimental conditions which could easily be scaled up to industrial level. All the products obtained, along with the refined Crambe abyssinica oil used as a reference, were analysed for viscosity, viscosity index, low-temperature behaviour and oxidative and hydrolytic stability. Results of tests, such as four-ball machine and Noack, are reported. The results show that several products covering a wide range of different applications can be obtained from the basic Crambe abyssinica oil, and, furthermore, the chemical modification of the Crambe abyssinica oil can, in some cases, improve thermal and hydrolytic sensitivity and even the tribological properties.     

PLC在香烟过滤嘴生产线上的应用

本文简要地介绍了香烟过滤嘴生产线的构成及我国在香烟过滤嘴生产线的开发应用情况,提出了ＳＬＨＰ００５仿丝牵伸联合机生产线的电气控制方案及以西门子Ｓ７－３００为控制主体的硬件配置组网和软件设计。     

Synthetic adipic complex tetraesters as eco‐friendly lubricants

The paper presents results concerning the synthesis and characterisation as lubricants with biodegradability potential of some complex tetraesters realised on the basis of adipic acid and different glycols such as (mono) ethylene, 1,3‐propylene, 1,4‐butylene, 1,5‐pentamethylene, 1,6‐hexamethylene, diethylene and triethylene glycol, respectively, along with oleic acid used, considered as an end, final segment or as a capping element. On the basis of a regular alternation or successive distribution principle of the polar and nonpolar chemical functions equally distributed, shared out on the length of a sufficient, satisfactorily long, large molecule, valuable synthetic complex tetraester lubricants considered as eco‐friendly base oils with biodegradability potential were performed. These products showed very good tribological properties, such as high viscosity indices and high flash points, and also very good lubricity features. Copyright © 2013 John Wiley & Sons, Ltd.     

Mechanism of atomic removal in elastic emission machining

Elastic emission machining (EEM) can be thought of as a machining method utilizing the chemical activity of a particle surface, rather than a liquid echant as in chemical etching. Selecting the combinations of silicon as workpiece material and SiO₂, Al₂O₃ and ZrO₂ as the powder particles, the material removal rate during machining was examined. Different combinations of workpiece materials and powders affected removal rates strongly, so that the machining process was considered from the standpoint of the atomic interactions at the interface between the workpiece and the powder particles. The surface voltage of the workpiece with adsorbed powder particles was measured as one of the parameters representing the interfacial interactions, and correlations with removal rates were obtained.     

Intergrowths and defect structures in Bi9Ti3Fe5O27 revealed by high-resolution electron microscopy

A high-resolution 500 kV study of the long-period (n = 8) perovskite Bi₉Ti₃Fe₅O₂₇ has revealed a variety of order/disorder effects, in marked contrast to low-n materials, as well as the occurrence of a new two-dimensional superlattice structure corresponding to a 3 × d₁₁₀ ordering along the bismuthate layers. Intergrowths of the 2-D SL phase with the ‘usual’ perovskite/bismuthate phase, as well as sharp interfaces between these two phases, were observed and the common occurrence of steps along these interfaces suggested ledge migration as one possible transformation mechanism. Coherent intergrowths of structural elements rather similar to tetragonal-tungsten-bronze (TTB)-type were also found and these sometimes appeared to be relics of the super-lattice phase. The chemical implications of the sevarious observations are briefly discussed.     

The effect of CeF3 on the mechanical and tribological properties of Ni-based alloy

The Ni-based alloys with various proportions of CeF₃ as lubricant and active element were prepared by hot-pressing and sintering in an intermediate frequency inducing oven. The effects of CeF₃ addition on the tribological and some mechanical properties of the alloy were investigated on a pin-on-disk tribometer. The results indicated that the compressive strength and impact roughness as well as the tribological properties of the alloy were improved by adding 3 wt% CeF₃. It was supposed that CeF₃ can effectively act as an additive, which exhibits beneficial effects on the mechanical and tribological properties of Ni-based alloy.