带法兰盘的轴承套圈的加工方法

为了提高带法兰盘的轴承套圈的加工精度,更好的实现轴承的定位安装,针对不同产品的结构特点,改变了常规的加工工艺流程,以先进的数控加工设备取替了专用机床,优化了加工方法,提高了产品合格率和生产效率。     

Estimation of time-of-arrival errors of acoustic-emission signals by the threshold method

A technique for determining the times of arrival of acoustic-emission (AE) signals at the probes of a piezoelectric antenna with simultaneous estimation of their errors is considered. To increase the localization accuracy, it is proposed to refine the times of arrival by linearly approximating the leading edge of an AE signal taking into account the influence of noise. The slope of the leading edge is calculated according to the criterion of the minimum rms deviation from the signal envelope using the moving-window method. Examples of use of the developed method for calculating the coordinates of flaws in strength tests of structural elements are considered.     

Forecasting the strength of concrete during its hardening by the acoustic-emission method

Concrete structure formation has been studied by the acoustic-emission method. Using the results of the experimental research, a relationship has been revealed between the acoustic-emission data registered during the first 24 hours of hardening of a concrete composition and its strength at the age of 28 days. Informative parameters of acoustic-emission data have been determined that correlate with the strength of the concrete composition at the age of 28 days.     

Estimation of the strength and lifetime of welded constructions using the acoustic-emission method

Strength margins according to different criteria (static strength, low- and high-cycle fatigue, crack growth resistance), as well as the initial lifetime, accumulated long-term and cycle damages, and remaining lifetime, are classified as the main characteristics of the strength and lifetime of machines and constructions. In order to estimate the accumulated damage at the first fracture stage, it is sufficient to determine the values of parameters involved in the fracture growth equation. In order to estimate the lifetime, it is sufficient to solve this equation with regard to the accumulation time of the critical damageability based on estimation of the value of the diagnostic parameter. The possibility of estimating these characteristics using registration of AE signals and a model proposed in previous papers is shown.     

Estimation of the strength and lifetime of technical objects using the acoustic-emission method

Estimation of the lifetime of a construction consists of forecasting the time remaining before failure and is based on extrapolation of the time dependences of the state parameters of a technical object to their critical values. The use for this purpose of simplified damageability models (e.g., a hypothesis of linear summation of flaws) and the absolute values of acoustic-emission (AE) parameters (e.g., activity, counting rate, duration of pauses) leads to a dependence of the estimate results on a large number of destabilizing factors and, as a result, to low accuracy or laboriousness of these techniques. An earlier suggested micromechanical model of AE parameters makes it possible to find a trade-off between simplicity and accuracy.     

Dependence of the number of acoustic-emission pulses on the mechanical testing load of bearing races in an axle unit

Acoustic-emission tests of flawless bearing races in axle units are performed on a special loading stand. Dependences of the number of AE pulses on the loading force are established for objects with and without flaws. The spatial distribution of AE sources in the flawless bearing races and a change in activity during reloading of the races are studied. Numerical parameters of the local-dynamic rejection criterion are determined on the basis of the analysis of the experimental data on races containing fatigue cracks.     

Enhancement of the acoustic-emission method use for diagnostics of rolling stock cast parts

The techniques for acoustic-emission (AE) testing of cast parts (side frames and bogie bolsters) of a freight-car truck, which improve the reliability of evaluating their engineering state at different stages of the working cycle and decrease their repeated rejection, are considered. It is proposed to determine the degree of damage and the service life of cast parts on the basis of the analysis of AE-signal sources, which have the highest integral characteristics.     

On the information capacity of the invariant method in the analysis of resampled acoustic-emission streams

Specific features of the diagnostics of a prefracture state using the method of invariants of acoustic emission (AE) are considered. It is shown that “resampling” of a stream by measuring each mth pulse abruptly reduces the randomness of the properties of the initial AE stream. This makes it virtually impossible to determine the degree of hazard of a flaw on the basis of some statistical parameters of resampled Erlang streams (naturally, also including the AE invariant method) even at relatively small recalculation coefficients.     

Clustering of sources of acoustic-emission signals by the leading-edge rise rate

It is shown that the method of clustering by the leading-edge rise rate of the envelope of an acoustic-emission (AE) signal makes it possible to reduce the time of calculation of the coordinates of flaws as compared to the clustering by shape. The developed technique realizes the on-line localization of massive flows of AE signals with an accuracy sufficient for practical application. The practical parameters of using the method for operation on a steel sheet with a simulator obtained for a statically loaded duralumin specimen and for welding of steel specimens with aluminum and titanium inserts are considered.     

Features of the search for leaks in pipelines of heat networks using the acoustic-emission method

An algorithm for filtering acoustic-emission signals and a technique for measuring the velocity of sound during searches for leaks in pipelines of heat networks are considered. The results of experimental studies are presented.     

轴承套圈磨加工中的振动及其影响

磨削振动对套圈加工表面质量和磨具寿命有不良影响，通过对磨削振动的判断，找出其产生原因，相应采取适当措施减少振动，效果良好。     

大型圆柱滚子轴承套圈锻造方法改进探讨

大型圆柱滚子轴承内、外圈锻造原通过箱式气体加热,冲孔、扩孔成型等工序来完成,其锻件质量与操作者的经验及技术水平有很大关系。针对上述不足,采取中频加热、碾扩后上压力机整形的方法,解决了套圈尺寸及形状误差难以控制的问题。     

轴承套圈机械打字上座设计

根据轴承套圈的尺寸,将轴承套圈机械打字上座设计为固定式与可调式两种结构,并叙述了其操作方法。经使用验证,该设计结构紧凑合理,保证打字质量,满足客户需求。     

双环永磁轴承径向偏移承载能力的研究

在分析永磁轴承基本结构的基础上,提出了双环永磁轴承的结构,并进一步分析了该轴承的工作原理和径向偏移承载能力,推导了径向磁吸力、轴承间隙、剩磁之间的关系,经仿真其结果表明:大部分磁力线形成闭合回路,最大限度地减少了磁力线的对外散发,保证了永磁环性能的稳定,延长了永磁环的使用寿命;径向磁吸力随轴承间隙的增大逐渐减小,随表面剩磁的增加而增大;轴承的径向刚度等于长度为半周长的线性模型的刚度。     

A local method for loading a tested object during acoustic-emission diagnostics

A new acoustic-emission diagnostics method in which there is no need to load an entire structure has been studied. This method of monitoring (as a conventional acoustic-emission method) is based on making a deformation of the tested surface; however in this case, the load is applied to a preliminarily chosen site of the tested object in the most dangerous area.     

Evaluation of the condition of a metal using the acoustic-emission method: Prospects and problems

Examples are presented of the use of a methodology that combines the methods of acoustic emission and kinetic indentation for the evaluation of the condition of metals that are subjected to diverse exposures (i.e., thermal treatment, cyclic loading, severe plastic deformation, etc.), which cause both structural and phase changes in a metal and lead to changes in mechanical properties as a result. A wide range of the potentials of the suggested methodology for resolving problems of industrial safety are demonstrated.     

高压法微小电容检测

微小电容测量电路广泛应用于各种工业过程中,尤其是在用于电容层析成像系统中.大多数的微小电容测量电路采用了基于交流电流测量或直流充放电方法.这些方法的共同优点是具有较高的灵敏度和抗杂散电容能力.而且其交流激励电压或直流充放电电压一般在20 V以下.为进一步提高微小电容测量的灵敏度和分辨力,本文提出了一种高压交流激励方式电路,该电路将交流激励电压提高到几百至上千伏.实验表明该方法大大提高了微小电容测量的灵敏度和分辨力,同时具有良好的稳定性和线性度.     

渗碳钢制轴承套圈渗碳及热处理工艺

通过对某渗碳钢制轴承套圈渗碳工艺的试验研究,达到足够的有效硬化层深度、表面碳含量且渗碳层组织中无粗大网状碳化物等要求,使轴承内、外套圈的工作表面具有高的硬度、耐磨性、高抗疲劳性,而心部具有高的强韧性等性能。     

Nondestructive testing of the quality of blanks for the fabrication of hot-rolled strips using the acoustic-emission method

A method for predicting the quality of hot-rolled strips based on the results of recording acoustic-emission (AE) signals is proposed. Considering the development of flaws in a slab under the effect of technological loads during rolling as a process of the loss of the integrity of the slab material, the AE signals recorded in the course of diagnostic loading of experimental specimens are interpreted from the standpoint of a micromechanical model and the developed methodology for nondestructive testing of the strength of a material and quality estimation. The most informative diagnostic parameters and diagnostic features of the method are determined by comparing the results of the interpretation with the defect level of the obtained strip.