Experimental investigation,prediction and optimization of cylindricity and perpendicularity during drilling of WCB material using grey relational analysis

Manufacturing is always the heart of majority of industries. Drilling is an extremely important and an essential machining process which requires a lot of attention as in most of the cases it is required for assembly purposes. Majority of the holes produced during drilling are made with the help of Vertical Machining Centre (VMC) meant for pin- hole assembly. Though the tolerance is within limit, assembly problems arise due to the improper geometry of these holes. Various geometrical tolerances like cylindricity, circularity, perpendicularity and position errors are responsible for such assembly problems. This investigation is focussed on cylindricity and perpendicularity in the drilling of Wrought Cast Steel Grade B (WCB) material using SOMX 050204 DT insert. In this work, effect of machining variables like cutting speed, feed rate and depth of cut (canned cycle) are investigated and optimized using grey relational analysis (GRA). Reliable experiments are conducted based on a 3³ full factorial, replicated twice. Second order regression models are developed for predicting cylindricity and perpendicularity. The models’ adequacy has been checked by calculating correlation coefficient. It shows that the developed models are well fitted for the prediction of responses within the specific range of input variables.     

现行圆柱度测量方法分析及采样方案新策略

在对新一代产品几何技术规范GPS(geometrical product specification)采样要求分析的基础上,采用现有仪器对样品轴的圆柱度进行多组实测,同时结合计算机模拟分析,深入探讨现行测量方法的局限性和存在问题,即现有的仪器和现行的测量方案难以满足GPS采样规范隐含的采样面密度和采样频率要求.计算机模...     

控制薄壁电动机机座车削变形加工工艺

薄壁电动机机座的精度主要通过机械加工来保证。从薄壁电动机机座机械加工的找正、定位方法以及确定切削工艺参数等方面,论述了薄壁电动机机座的精密加工技术,其圆柱度控制在0.1mm以内,两端止口同轴度控制在0.1mm以内,全跳动控制在0.1mm以内。该技术对大型薄壁电动机机座的精密加工具有指导作用。     

基于误差分离技术的几种圆柱度测量模型分析

对国内提出的四点法、五点法、两测头法等几种典型的基于误差分离技术的圆柱度测量模型分别进行了分析，探讨了这些测量模型中存在的一些问题。     

Web-based algorithm for cylindricity evaluation using support vector machine learning

This paper introduces a cylindricity evaluation algorithm based on support vector machine learning with a specific kernel function, referred to as SVR, as a viable alternative to traditional least square method (LSQ) and non-linear programming algorithm (NLP). Using the theory of support vector machine regression, the proposed algorithm in this paper provides more robust evaluation in terms of CPU time and accuracy than NLP and this is supported by computational experiments. Interestingly, it has been shown that the SVR significantly outperforms LSQ in terms of the accuracy while it can evaluate the cylindricity in a more robust fashion than NLP when the variance of the data points increases. The robust nature of the proposed algorithm is expected because it converts the original nonlinear problem with nonlinear constraints into other nonlinear problem with linear constraints. In addition, the proposed algorithm is programmed using Java Runtime Environment to provide users with a Web based open source environment. In a real-world setting, this would provide manufacturers with an algorithm that can be trusted to give the correct answer rather than making a good part rejected because of inaccurate computational results.     

三测头法误差分离技术的理论与试验

建立回转体零件频域三测头法误差分离数学模型,采用离散傅里叶变换法对误差分离基本方程进行求解,并通过计算机仿真对该数学模型进行验证和分析;采用经TALYROND262形状测量仪标定过的试件,在MB1332A半自动外圆磨床上进行圆度、圆柱度和轴线直线度误差在位测量对比试验,仿真结果和试验均成功地证明理论和数学模型的正确性,并得出结论:频域三测头误差分离方法基本上能实现各项误差的完全分离,适于在位测量,并可获得较高的在位测量精度。     

直角坐标系下计算圆柱度误差的一种实用算法

建立了采样数据为直角坐标值、坐标原点可以任意选取、各离散采样点之间也不要求为等角度间隔情况下，圆柱度误差评定的最小二乘数学模型。通过精度分析，证明该模型具有理论的正确性与实际的可行性。     

RESEARCH ON THE MINIMUM ZONE CYLINDRICITY EVALUATION BASED ON GENETIC ALGORITHMS

A genetic algorithm (GA)-based method is proposed to solve the nonlinear optimization problem of minimum zone cylindricity evaluation. First, the background of the problem is introduced. Then the mathematical model and the fitness function are derived from the mathematical definition of dimensioning and tolerancing principles. Thirdly with the least squares solution as the initial values, the whole implementation process of the algorithm is realized in which some key techniques, for example, variables representing, population initializing and such basic operations as selection, crossover and mutation, are discussed in detail. Finally, examples are quoted to verify the proposed algorithm. The computation results indicate that the GA-based optimization method performs well on cylindricity evaluation. The outstanding advantages conclude high accuracy, high efficiency and capabilities of solving complicated nonlinear and large space problems.     

Application of kinematic geometry to computational metrology: distance function based hierarchical algorithms for cylindricity evaluation

This paper applies kinematic geometry to investigate the problem of determining the cylindricity error of a mechanical part by using measurement points obtained with a coordinate measuring machine. For a point expressed in the machine reference frame and a nominal surface represented in its own model frame, a signed point-to-surface distance function is defined, and its increment with respect to the differential motion of the surface is derived. On this basis, four commonly used cylindricity evaluation methods, i.e., minimum zone cylinder method, maximum inscribed cylinder method, minimum circumscribed cylinder method and least-squares cylinder method, are formulated as nonlinear constrained optimization problems and nonlinear least-squares problem, and efficient sequential approximation algorithms are developed to solve them. For enhancing the performance of the algorithms, two relevant optimization problems and corresponding algorithms, i.e., localization of cylinder and minimum variance fitting of cylinder, are introduced to analytically provide proper initial solutions. By organizing all involved algorithms in a hierarchical structure, four complete cylindricity evaluation algorithms are presented. Comparing with existing methods, they have the advantages of implementational simplicity, computational efficiency and robustness. Examples confirm the validity of the proposed hierarchical algorithms.