Problems of engineering diagnostics of electron-beam welding

Features of electron-beam welding (EBW), various types of flaws arising in welded joints during EBW, and the factors causing these flaws’ appearance are considered. The effects of beam focusing and the thickness of the welded metals on the shape of a seam are demonstrated. EBW flaws are classified. The difficulties associated with obtaining informative parameters during EBW are analyzed. Radiation and acoustic methods for engineering diagnostics of EBW are considered. New approaches to the construction of systems for diagnostics of EBW are proposed. Experimental results are presented.     

电动轮技术在电动汽车中的应用及发展趋势

介绍了电动轮的结构、技术优势,电动轮电动汽车的布置方式以及控制策略。对目前电动轮技术中的关键技术问题和电动轮电动汽车的发展趋势进行讨论,提出了相应的发展建议。     

在LabVIEW中非NI公司数据采集卡驱动程序的开发

介绍了在虚拟仪器软件LabVIEW中开发数据采集卡驱动程序的三种方法．指出了它们各自的适用场合与优缺点、并以实例加以说明。     

Models of vibrational transfer and filtration of vibroimpact processes

Examples of the appearance of vibrational motion modes, which lead to excess noise and premature wear of machine parts and mechanisms are presented. Models of mechanical filters of various types are considered, and the problems of the nonlinear and linear filtration of wave-vibrational processes are discussed. The models of the vibration-conducting media, involving the nonlinear vibrational guides of a complex structure, are presented. The analytical studies of the problems associated with the passage of periodically strongly nonlinear (vibroimpact) processes through the multidimensional machine designs, which are modeled by means of discrete 2D mechanical systems with regular structures, or multidimensional mechanical filters for low frequencies, are performed. The physical sense of the derived solutions is obtained, the computational formulas are derived, and the main dynamic effects are discussed. The notion of filter metrics is introduced.     

薄板成形计算机仿真中摩擦模型的研究进展

概括和总结了薄板冲压成形计算机仿真中摩擦模型的研究现状，指出了建立实际的摩擦模型应注意的一些问题，讨论了该领域有待解决的问题，指出了进一步的研究发展方向。     

铜合金表面激光熔覆研究现状

为了提高铜合金的表面耐磨性能,激光熔覆技术已被用于铜合金的表面处理;总结了铜合金表面激光熔覆的特点,评述了铜合金表面熔覆材料体系的研究现状和激光熔覆技术工艺,分析了熔覆层的表面性能,阐明了铜合金表面激光熔覆存在的主要问题和相应改进途径,并提出了今后的研究方向。     

Problems of application of multi-frequency methods in industrial measurements of resonant one-ports

In the era of computerised instrumentation, new measurement methods of resonant elements are developed. In the paper multi-frequency methods are considered from the point of view of industrial applications. Restrictions of the methods connected mainly with high Q-factor of measured object, its multi-resonance character and non-linearity are discussed and means to overcome them are proposed.     

弹性金属塑料瓦推力轴承润滑性能分析

本文利用三维热弹动力润滑理论和有限元分析模型对大型水电站弹性金属塑料瓦推力轴承的弹流动压润滑性能进行了研究，提出了设计塑料瓦时应注意的问题，并将塑料瓦推力轴承的某些性能与钨金瓦做了分析比较。     

静电涂敷荧光粉带电机理

根据电晕放电理论,导出由放电针和玻管组成的圆筒形放电系统的电场分布,并导出由负离子与粉粒碰撞,使粉粒带电的数学表达式,对其结果进行了分析.     

汽车前照灯系统光学设计方法研究

随着汽车工业的飞速发展，对汽车车灯照明的效果也越来越加以重视。这里介绍了汽车前照灯系统光学设计的原理和方法。重点介绍了带有配光镜的车灯系统的设计方法并建立了数学模型，叙述了模拟实际灯具、绘制模拟图形和进行光度处理的方法，并且通过实例介绍了利用设计软件进行设计的效果。     

Optimization of material hardness of solid-rolled wheel of freight cars

Results on the wear of solid-rolled wheels of increased hardness designed for freight cars are discussed. The friction model of the wheel-rail pair is developed considering the variations in wheel-material hardness provided for in the standards, as well as the loads acting during wheel operation. Methods of mathematical experiment planning are used to solve the problem of optimizing the material hardness. Statistical data on the performance of solid-rolled wheels are expounded and recommendations on the choice of wheel material hardness are given.     

液压挖掘机保护结构计算机仿真与实验

液压挖掘机司机保护结构对于保证操作人员的安全是十分重要的,加装司机保护结构是国产挖掘机进入欧美市场的必要条件．为使挖掘机司机保护结构制造企业在设计阶段掌握产品性能,避免设计失误,采用动态模拟方法对挖掘机司机室顶部保护结构受落物冲击过程进行了仿真,对前保护结构进行了静态模拟．建立了保护结构的非线性有限元模型,讨论了接触算法和载荷施加方法,得出了顶保护结构受冲击点的位移时间历程曲线以及前保护结构在载荷下的位移和吸能曲线．在实验台上对该结构进行了试验,试验结果和仿真结果吻合较好．保护结构的仿真为结构设计提供了依据．     

PCB 微钻切削刃结构参数化分析

PCB用硬质合金钻头是一种形状复杂的带螺旋槽的微孔加工工具,由传统的麻花钻衍生而来.微钻的结构参数与切削刃的切削性能密切相关,这些参数之间相互联系、相互影响.本文通过定义旋转矩阵建立了整体坐标系下微钻的后刀面数学模型,以向量形式推导了相应的横刃斜角和切削刃的数学表达式,定量分析了影响其切削性能的结构参数,得出相关结论,...     

电梯检验检测技术综述

论述了电梯检验的类型和电梯检测的主要内容,并分析了电梯检验过程中存在的危险源,同时提出了预防电梯事故的基本措施,最后给出了电梯检测的一般流程。     

换热器板翅结构数值模拟及强度设计准则修正

传统的紧凑型换热器设计中隔板与翅片的强度设计准则的不合理性在于过于保守,使得计算厚度值偏大.通过全参数化的有限元数值模拟,获得了一系列数据,分析了翅片和隔板中应力与结构参数的关系,结果表明翅片和隔板中应力值较原经验公式的计算值小,尤其是隔板中的应力与原公式的规律也存在明显差别.利用数据拟合技术,获得了翅片和隔板应力新的工程计算表达式,是对现有板翅结构设计规范的有效补充.     

非线性对Coriolis质量流量测量管振动特性影响的理论研究

以直管式Coriolis质量流量计为例，从理论上研究了非线性对测量管振动特性的影响。建立了考虑非线性的测量管振动方程；用Galerkin法对振动方程进行了离散化处理，将连续体的偏微分方程简化为关于广义坐标的二自由度非线性振动方程；用多尺度法对离散化的振动方程进行定性理论分析，指出了非线性对测量管振动的影响，给出了非线性引起的附加振动成份。所得结论与有关文献给出的实验结果一致，对测量管的设计和输出信号处理具有理论指导意义。     

Studies of the dynamics of free microoscillations of a pendulum supported by two balls

Approaches to the measurement of rolling friction by the method of free oscillations of a pendulum are considered. The models of energy dissipation for the oscillation amplitudes within the contact area are analyzed. The friction characteristics are assessed for two surfaces of silicon that differ by the quality of the processing. Criteria for selecting an adequate model based on the nonlinear regression analysis of the experimental results are proposed.     

Evolution of methods of assessing the accuracy of metal-cutting machines

The evolution of concepts of accuracy and attainable machining accuracy are considered. The physical aspects of accuracy are discussed. The changes in the level of precision since 1800 are outlined, with predictions of what is attainable in the future. The energy barrier to accuracy is analyzed for various cutting technologies.     

三种典型压力AGC的仿真研究

目前,国内普遍使用的AGC控制方式有三种——动态设定型AGC、测厚计型AGC、—BISRA-ACG,笔者给出了三种系统的数学模型和系统框图并应用Matlab中的Simulink对这三种典型的压力AGC进行仿真,对三种控制方式的动态响应频率、控制精度等进行比较。     

碳氢制冷剂热物理性质的计算

将Carl的热物理性质计算关联式应用于碳氢制冷剂HC290和HC600a，在制冷空调的常用温度范围内，检验了Carl系数的计算精度，并进行了重新拟合，使拟合误差比应用Carl系数的误差减小了一个量级左右，效果良好，可用于系统仿真和快速工程计算。另外补充了新的饱和蒸汽的热物理性质计算方程及系数，给出了全部计算偏差结果，最后对数据拟合的精度问题作了简要分析。