Modeling of cutting force coefficients in cylindrical turning process based on power measurement

The cutting force is an important physical quantity in metal cutting, and the cutting force coefficients are the basis for establishing the cutting force model. In this paper, the relation between the cutting power and the cutting force coefficients is established. A cutting power model was established with a linear relationship between the spindle power and material removal rate (MRR). The power-based model of the main cutting force coefficients is proposed by extracting the linear equation coefficients of the power-MRR function. The power-based model of feed force coefficients is established as a quadratic polynomial equation between the motor power of the feed axis and feed rate. And the cutting force coefficients and the edge force coefficients of feed force are expressed respectively by the two orders of coefficients of the equation. The thrust force coefficients are indirectly calculated from the relation between tangential cutting force and thrust force with friction angle of tool-chip. The power-based models were verified by a series of cutting tests regarding material properties, cutting parameters, and axial directions. The results show that the cutting force coefficients obtained by measuring the cutting power have good correspondence with that identified by dynamometer.     

Safety and strength coefficients of mechanical structures

Mechanical structures have been developed for defining strength coefficients, which confirm the specified reliability requirements and have been referred to as safety coefficients. Safety coefficients have been utilized in the theoretical and experimental development of structures. These coefficients are the products of several particular coefficients found by probabilistic and statistical procedures, namely, the average strength coefficient for meeting the reliability requirements, the relation of the average mechanical tension of the material to the tension guaranteed by GOST, the coefficient for the test plan and the incompleteness of the test results, the coefficient for the difference between the dynamic response coefficients in dummy blocks and mechanical structures, the coefficient for the replacement of multiple loading by single loading, etc. Safety coefficients have been utilized during independent and dependent tests.     

互相关系数的分解研究

本文通过理论分析和分解处理法研究两个典型信号之间的互相关系数的构成及其影响因素，作者引用了宏观相关系数的逐次分频相关系数的概念。     

涡轮叶片尾缘半劈缝冷却结构压力系数的实验研究

对九种不同几何结构的尾缘半劈缝结构的压力系数进行了实验研究,在不同吹风比和雷诺数下测得了缝中心和肋中心后沿流向压力系数的分布,分析了各种因素对压力系数的影响。结果表明肋中心后和缝中心后的压力系数没有多大的差别。半劈缝的几何结构对压力系数有很大的影响,当缝宽一肋宽比增大（在0．67到1．5的范围内）时,压力系数随之增大;当缝高一唇厚比增大（在0．53到2的范围内）时,压力系数变化不是很大,但主流和二次流的参混距离减小。在几何结构一定的情况下,压力系数随雷诺数（5,000到15,000）的增大有小幅度增大,在X／H小于某一值时。压力系数随着吹风比（0．5到2．0）的增加是增大的,但在X／H大于这一值时压力系数随着吹风比（0．5到2．0）的增加却是减小的,但是变化幅度并不是很大。     

An experimental identification model of rotordynamic coefficients of seals using unbalanced synchronous excitation method

This study presents an improved impedance method based on unbalanced synchronous excitation to identify the rotordynamic coefficients of labyrinth seals. The rotordynamic coefficient test is implemented near the cylinder resonance frequency to enlarge the influence of seal force. The force generated by the rotor unbalance is used to provide synchronous frequency excitation for the rotordynamic coefficient test. Four unique equations are set up under two sets of different rotor unbalance conditions to obtain four unknown complex rotordynamic coefficients. The factors that influence the rotordynamic coefficients of seals, namely, unbalance mass, inlet/outlet pressure ratio, and rotating speed, are considered. The dynamic coefficients are minimally affected by different rotor unbalances. The direct items are nearly equal with same signs, whereas the cross-coupled items are nearly equal with opposite signs. All coefficients increase with increasing inlet/outlet pressure ratio and rotating speed. The direct stiffness coefficients increase more quickly than the cross-coupled items. In addition, the effect stiffness and effect damping coefficients are analyzed; results indicate that both coefficients increase with increasing rotating speed.     

基于小波变换的零件图像数据融合

提出一种基于小波变换的图像数据融合的方法,对多源图像进行分解,将高频区域中的绝对值较大的系数作为重要小波系数;在低频区域,对逼近系数进行加权平均得到新的逼近系数,然后进行小波重构。实验表明,该方法是实用的。     

常系数齐次线性微分方程组的一个性质及应用

常系数齐次线性微分方程组在一定条件下存在与其等价的常系数齐次线性微分方程,它们具有相同的特征多项式,因而有相同的特征根。常系数齐次线性微分方程组的通解可以通过与其等价的常系数齐次线性微分方程的通解求得。     

An improved dynamic milling force coefficients identification method considering edge force

The identification of the dynamic coefficients is the key to realize accurate simulation of dynamic milling process. To enlarge the scope of dynamic simulation without ignoring edge force, an improved method is presented to calculate milling force coefficients. In this method, linear approximation of average milling force is integrated with multiple linear regressions by supposing that milling force coefficients are time invariant for small variation of feed rate. Therefore, both the shear coefficients and the edge coefficients can be calculated simultaneously. A comparison of simulated milling force with and without the edge force is illustrated and the result shows that the accuracy is higher if the edge force coefficients are considered. This method casts new light on fast and accurate simulation of the dynamic milling force in real industrial environment.     

CALCULATION OF THE SPECIFIC CUTTING COEFFICIENTS AND GEOMETRICAL ASPECTS IN SCULPTURED SURFACE MACHINING

This article presents a method for obtaining the shear and ploughing specific cutting coefficients for a ball-end milling cutting force model. Thus, by using the proposed calculation method, the need for introducing variable shear cutting coefficients has been identified. This fact is due to the dependency among the specific cutting coefficients and the cutting edge inclination angle, which is variable in ball-end mills. Linear, quadratic and cubic polynomial shear cutting coefficients have been calculated, and the degree of adjustment obtained in each approach has been analyzed. At the same time, the expressions of the ploughing specific coefficients have been analyzed. The proposed calculation method has been applied to the following materials: a 7075-T6 aluminum alloy and a 52HRC AISI H13 tool steel. The results obtained from the validation demonstrate how the obtained coefficients are capable of predicting cutting forces over a wide range of cutting conditions. Finally, the results from applying the coefficients calculated in horizontal slot milling tests have been introduced in a model capable of calculating cutting forces in slope milling cases, which validates the calculation method proposed as a generic method for estimation of cutting coefficients.     

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。     

基于小波变换的零件图像融合与边缘检测

提出基于小波变换的零件图像数据融合和边缘检测的方法,对图像进行分解,将高频区域中的绝对值较大的系数作为重要小波系数;在低频区域,对逼近系数进行加权平均得到新的逼近系数,然后进行小波重构实现图像数据融合。应用小波变换对融合图像进行多尺度边缘检测,获取图像边缘,或对图像进行小波多尺度边缘检测,然后融合边缘。     

The cross-coupling dynamic coefficients of tilting-pad bearings

There is some misconception in the literature concerning the crosscoupling stiffness and damping coefficients of tilting-pad bearings; these have been reported as equal to zero. Analytical expressions of the dynamic coefficients of the bearing in terms of the dynamic coefficients of the individual pads have been derived to show that the cross-coupling coefficients of the bearing cannot in general be zero.     

纹理表面滑动摩擦稳态摩擦学性能

基于稳态滑动摩擦系统模型,采用球-盘摩擦副定量分析研究法向载荷、滑动速度、初始表面纹理和摩擦副材料对稳态摩擦因数的影响,得到稳态摩擦因数在不同工况下的变化规律。结果表明：滑动摩擦的稳态摩擦因数与磨损率正相关,周向纹理表面的稳态摩擦因数最大,无纹理表面的稳态摩擦因数次之,径向纹理表面的稳态摩擦因数最小;无论何种初始表面形貌,随着转速的增加,稳态摩擦因数先减小后增大,随着法向载荷的增大,稳态摩擦因数呈增长趋势;较深较宽的表面纹理具有更大的稳态摩擦因数和更大的瞬时波动;稳态摩擦因数也与摩擦副材料的选取有关。     

Single particle raster image analysis of diffusion for particle mixtures

Recently we complemented the raster image correlation spectroscopy (RICS) method of analysing raster images via estimation of the image correlation function with the method single particle raster image analysis (SPRIA). In SPRIA, individual particles are identified and the diffusion coefficient of each particle is estimated by a maximum likelihood method. In this paper, we extend the SPRIA method to analyse mixtures of particles with a finite set of diffusion coefficients in a homogeneous medium. In examples with simulated and experimental data with two and three different diffusion coefficients, we show that SPRIA gives accurate estimates of the diffusion coefficients and their proportions. A simple technique for finding the number of different diffusion coefficients is also suggested. Further, we study the use of RICS for mixtures with two different diffusion coefficents and investigate, by plotting level curves of the correlation function, how large the quotient between diffusion coefficients needs to be in order to allow discrimination between models with one and two diffusion coefficients. We also describe a minor correction (compared to published papers) of the RICS autocorrelation function.     

径向-推力联合浮环动静压轴承动态特性试验研究

在径向-推力联合浮环动静压轴承理论计算和分析的基础上,设计制造了轴承试件及相关的试验装置,改制了试验台。采用静动法和激振法相结合首次测得了径向部分内外膜8个刚度系数和轴向部分2个刚度系数及径向部分总的4个阻尼系数和轴向部分的1个阻尼系数。根据试验数据绘制不同转速下各动特性系数随偏心率的变化曲线,并与理论计算结果进行比较,二者基本一致。     

Nonlinear optical properties of chromophore-containing polyimides with covalently attached dyes

Spectral dependences of quadratic nonlinear coefficients of new chromophore-containing polyimides with covalently attached DR13 chromophore molecules are synthesized and studied by the second-harmonic generation method in the fundamental radiation wavelength from 800 to 1400 nm. The obtained record values of quadratic nonlinear coefficients are 80 to 120 pm/V. Dispersions of refractive indices and extinction coefficients in the spectral range from 400 to 800 nm are determined by spectral ellipsometry, resulting in the improved accuracy of nonlinear coefficients..     

短密封动力学分析及计算

参考文献（１,２）利用紊流整体流动理论,考虑了惯性项的影响,对短密封的动特生系数等进行了详细地推导,并研制出计算程序,对短密封动特性系数进行精确计算。     

跨音速翼型的抖振特性研究

采用二元非定常Ｎ－Ｓ方程为控制方程,计算跨音速翼型升力系数和力矩系数的 时间历程。根据气动力系数的脉动量急剧上升的起始点确定抖振起始边界。气动力 系数脉动量的大小可用来表示抖振强度。以ＮＡＣＡ００１２翼型为算例,计算结果和风 洞实验结果以及其它计算方法的计算结果相比较,一致性很好。     

广义随机空间内相关系数的可靠性灵敏度

在可靠性分析的优化方法基础上,对随机变量间相关系数在可靠性分析中的重要性进行了分析;通过对随机变量间相关系数的可靠性灵敏度的计算和分析,得到了随机变量间相关系数的改变对结构可靠性的影响。通过实例计算来展示该方法在工程实际中的应用情况。研究结果为确定随机变量间相关系数在可靠性分析中的重要性以及对结构可靠性的影响提供了分析方法,为统计分析工作以及可靠性设计提供了有益的参考。     

An iterative numerical method for determination of temperature-dependent friction coefficients in thermomechanical model analysis of cold bolt forging

A set of temperature-dependent friction coefficients was developed to increase the accuracy of finite element (FE) simulations of cold bolt forging. The initially attained friction coefficients at different temperatures were calibrated with the iterations between the experimental and thermomechanical model extrusion test loads. The constant friction coefficient and the determined set of friction coefficients as function of temperature were then implemented to the simulations of the cold bolt-forging processes. Further calibrations and model validations were made based on the temperature measurements of the workpiece in the actual bolt-forging processes. To show the advantages of developed temperature-dependent friction coefficients, the loads of four different bolt-forging processes were compared with the thermomechanical model loads calculated using the constant friction and temperature-dependent friction coefficients. The modeling results indicated that the use of temperature-dependent friction coefficients in the FE simulations resulted in nearer temperature distributions and the loads of the workpiece during forging as compared with the use of a constant friction coefficient.