用划线方法确定曲轴的回转中心

曲轴毛坯锻造过程中由于压机异常、模具异常等因素影响造成曲轴毛坯成型偏离设计成型状态;曲轴锻造需要加热、曲轴热处理(调质)也需要加热,在加热过程再到冷却过程有应力的释放,当应力释放时曲柄销开档有不同程度的张开,由于应力分布不是均匀的所以各曲柄销的张开程度也不同造成曲轴弯曲;如不重新确定曲轴的回转中心,在后期加工过程中很容易使产品不合格,甚至可能会造成曲轴报废;为避免企业造成重大经济损失,划线确定曲轴的回转中心是必要的。     

Methodology for spectral emissivity measurement by means of single color pyrometer

The application of non-intrusive optical devices, such as infrared pyrometers able to measure the temperature of surfaces, makes possible the evaluation of emissivity curve of the tested materials at different temperature values. In this paper the authors propose a methodology for the spectral emissivity measurement by means of a single color pyrometer providing a semi-empirical formula, obtained experimentally at CIRA’s laboratory. The semi-empirical formula allows to know the actual emissivity value of the sample’s surface for whatever emissivity value set up on the pyrometer. The agreement between the experimental emissivity and the emissivity predicted by semi-empirical formula was verified.     

Energy loss due to misalignment of journal bearings

An analysis of a journal bearing describing a maximum allowable value of misalignment at a length to diameter ratio of unity is presented. The journal misalignment is allowed to vary in direction up to a direction normal to the axial plane containing the load vector. The results demonstrate that journal misalignment influences bearing behaviour. For the same load carrying capacity, a misaligned bearing consumes more power due to friction than an aligned one. An optimum position of misalignment has been found to be almost along the axial plane containing the load vector since it produces lower frictional losses and less lubricant leakage than any other.     

Frictional cladding by means of a flexible tool

Experimental and statistical models are developed for frictional cladding. The parameter ranges corresponding to the formation of coatings with complete coverage and a thickness of up to 15 μm are determined.     

The mapping of vortex fields around single and dual bluff bodies

The development and use of a system to measure important parameters of the vortex field in a coordinate grid around several single bluff bodies and dual bluff body combinations are described. Two hot wire sensors were used: a reference sensor at a fixed position and a moving sensor with position coordinates adjusted by using computer control. The strength, frequency and regularity of the vortex shedding are found from the auto-power spectral density of the moving sensor signal. The phase difference between moving and reference sensor signals is found from the cross-power spectral density function between the signals. The results are presented as maps of vortex parameters plotted as a function of sensor position coordinates. The main features of these maps, including the enhancement of vortex shedding from certain dual bluff body combinations, is then discussed.     

Hydrodynamic lubrication analysis of journal bearing considering misalignment caused by shaft deformation

Hydrodynamic lubrication characteristics of a journal bearing, taking in to consideration the misalignment caused by shaft deformation, are analyzed. Film thickness expression of the misaligned journal bearing is inferred. Film pressure, load-carrying capacity, attitude angle, end leakage flow-rate, frictional coefficient, and misalignment moment of a journal bearing are calculated for different values of misalignment degree and eccentricity ratio. The results show that there are obvious changes in film pressure distribution, the highest film pressure, film thickness distribution, the least film thickness, and the misalignment moment when misalignment takes place. Therefore, it is necessary to consider misalignment caused by shaft deformation when analyzing the lubrication of journal bearing.     

Elimination of spurious signal due to misalignment of magnetic axes of a differential magnetic-modulation transducer: Part I

Conditions leading to generation of a high spurious signal in a primary magnetic-modulation transducer (ferromagnetic probe) due to the transverse component of the terrestrial magnetic field have been studied. The compensating field as a function of the compensating component length has been calculated by the model of dipole interaction of magnetic charges. These calculations indicate that one of the conditions for efficient compensation for the spurious signal is a selection of an optimal length of the compensating component and its optimal separation from a magnetic sensor of a gradient-sensitive differential transducer.