基于本体的滚动轴承配合公差设计研究

针对滚动轴承配合公差设计难以智能化的问题,文章将本体引入到滚动轴承配合公差的设计中,为滚动轴承配合公差设计提供一种可行的方法。首先,分析总结滚动轴承配合公差设计影响因素;其次,使用OWL2构建滚动轴承的本体表示模型;再次根据滚动轴承配合公差设计的专家知识,使用语义网规则语言SWRL构建滚动轴承配合公差设计的语义规则;然后参照已构建的语义规则,使用Jess推理机得到滚动轴承配合公差的设计参数;最后,以圆柱齿轮减速器为例,验证所设计方法的有效性。     

刃口可调冲裁模调节结构设计

刃口可调冲裁模设计的核心内容是刃口调节结构设计,可调结构的受力和调节方法是设计依据.重点介绍了可调凸模的调节结构设计,分析了配合面的种类与特点,选择了适当的贴合面和导向面,确定了配合尺寸与公差.阐述了调节后的刃口结构特征以及冲裁力的计算方法.     

一种应用等效平面的公差分析方法

针对复杂机械系统公差分析问题,提出一种应用等效平面的公差分析方法。首先将零部件安装配合面的实际轮廓抽象为等效平面,用其单位法矢量表示位置和方向,在刚体条件下从设计信息中提取出等效平面的单位法矢量。在各个零件的局部坐标系下对单位法矢量位置和方向叠加,应用齐次转换矩阵计算出末端单位法矢量在基准坐标系中的位置和方向,从而对装配尺寸链进行求解。以某型圆柱磨齿机的砂轮修整器为例进行了公差分析计算,进行了1 000次的模拟计算,结果验证了设计精度指标,证明了该方法在公差分析方面的有效性。     

基于热力耦合变形的机床主轴公差建模方法研究

机床主轴的公差建模很少同时考虑切削力与摩擦热耦合变形的影响,导致公差模型与工程实际存在较大差异,难以保证机床主轴加工精度的问题。为此,研究一种基于热力耦合变形的机床主轴公差建模方法。根据机床主轴的实际工况,运用小位移旋量理论表达特征的几何变动,建立主轴原始几何误差的Jacobian-Torsor公差模型;根据几何变动修正Jacobian-Torsor公差建模,增加典型配合特征的公差变动表示模型;利用ANSYS计算主轴在切削力与摩擦热耦合作用下的变形量;将结果引入修正的Jacobian-Torsor模型,得到热力耦合变形下的机床主轴公差模型。结果表明：主轴与轴承的装配间隙在径向y方向上的平动量减少0.009 mm,沿着径向的转动量减少0.000 8 mm,过盈增大,加快了主轴的磨损,影响主轴的回转精度。所设计的模型可为机床主轴的公差设计提供参考,并可预测和改善主轴的工作性能。     

人工神经网络法选择公差与配合

机械工业发展的历史悠久,各个具体行业都积累了大量成功的经验。如何利用成功的样例,帮助设计人员迅速方便地解决当前设计中公差与配合的选择,是一个值得研究的问题。本文采用人工神经网络技术解决公差与配合的选择问题,对其中相关的数据预处理等技术也做了较为深入的研究,最后以国家标准推荐的13种优先配合为例,训练得到了网络的结构参数。     

基于本体和模糊理论的公差等级智能设计方法研究

在机械装配设计过程中,公差等级设计的实质是正确解决机械零件使用要求与制造成本之间的矛盾。传统公差等级的选择范围跨度较大,人为查表选择与经验选择居多,不确定性大,准确性与效率对设计者的经验要求很高。为减少公差配合中公差等级选用过程中对设计者经验的依赖,通过综合分析公差等级选用考虑因素,运用模糊综合评判原理构建公差等级智能选择本体规则,基于计算机本体语言建立公差等级优化推理模型。通过工程实例展示该方法的工作过程,验证了该方法的有效性。     

基于公差优化的民机缝翼滚轮设计分析

公差设计是飞机设计中重要环节,优化的公差设计不仅能达到满足产品要求的最简工艺性,提高装配精度和装配协调性,也可使复杂问题简单化。通过对飞机缝翼滚轮组公差分析、设计优化及仿真计算,揭示公差分配对此部位滚轮过载影响的机理,为解决飞机缝翼滚轮提前失效提供一种思路与方法。目前,公差优化的设计方案已在国内民机研发过程中展开应用,经过试验验证,问题已基本解决。     

孔系位置公差的换算

在加工中和设计中经常要将孔间距公差换算成直角座标公差,本文介绍了按等公差法和等公差级法分配x、y座标尺寸公差的计算方法。图7幅。     

对“公差与配合”、“形位公差”中的“三个原则”的统一解释

对于两个相配合的零件,按照国家标准公差与配合(GB1800—79)的“总论、标准公差与基本偏差”的决定,应该按照极限尺寸判断原则进行。但是,国家标准形状与位置公差(GB1182—80)的“形状和位置公差代号及其注法”标准中规定:对于配合零件,需要符合极限尺寸判断原则时,在其尺寸后加注符号“(E)”,这对大家贯彻“两项标准”中,造成了一定的混乱。最近,“公差配合”和“形位公差”两项标准技术委员会,对确定尺寸公差与形位公差之间关系的三个公差原则,做了进一步的研究和分析,并取得了一致的意见。现将国家标准总局,国标发办字(1982)088号文关于———批转机械工业部标准化研究所“对独立原则、包容原则和最大实体原则的     

注射模成型零件工作尺寸计算方法分析

通过对2种注射模成型零件工作尺寸计算方法的理论分析 ,指出了采用平均收缩率法存在的理论缺陷和实际模具设计中存在的问题 ,对极限公差法计算模具成型尺寸和公差作了分析和实例举证 ,说明了该计算方法能够较好地保证在注射模设计中成型尺寸和公差计算的正确性。     

THE TOLERANCE DESIGN MANUFACTURE AND RELIABILITY

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基于误差建模的配合间隙与注射模斜推杆机构强度关系研究

基于误差分析原理,提出了以实际尺寸和装配关系代替理论设计模型进行有限元分析的思想。以注射模斜推杆机构为分析对象,建立了考虑配合间隙的斜推杆机构有限元分析模型,研究了由公差控制的配合间隙与斜推杆机构的等效应力、接触应力的影响关系,为斜推杆机构设计提供了理论指导。     

An accuracy analysis of the peg-and-hole assembly problem

A peg-and-hole assembly may adopt clearance, transition or interference fits depending on the functional requirements of the particular design. The international standards that are used for the specification of the nature of a fit refer, nevertheless, only to dimensional deviations. They do not consider the actual geometry of the assembly components. Geometrical tolerances are assigned in addition to the dimensional tolerances whereas, for certain applications, the latter may also include some provision for them. Maximum and minimum functional clearances, dimensional and geometrical tolerances of a peg-and-hole assembly consist of a system where values of the first two variables are design-imposed and the dimensional/geometrical tolerance values have to be suitably allocated. This tolerance allocation cannot, however, be effected by a straightforward approach. The unknown variables are more than the available clearance/tolerance relationships and in the current engineering practice, the problem solution is usually based on experimental/empirical data and/or general tolerance assignment guidelines. The paper addresses this problem through a systematic analysis of the accuracy requirements of a peg-and-hole clearance fit assembly. The analysis is then followed by the development of a methodology for the evaluation of the dimensional and geometrical tolerances of the assembly components. The presented algorithm is further applied and discussed in a case study.     

Quantitative circularity tolerance analysis and design for 2D precision assemblies

Circular, cylindrical, or spherical features are fundamental geometric features in engineering. As precision requirement becomes more stringent, it is not sufficient to consider only size tolerance of circular and cylindrical parts. However, currently there is no quantitative and systematic way of assigning circularity and cylindricity tolerances. This paper investigates how to specify circularity tolerance quantitatively for 2D assemblies. Statistical matrices to quantify positioning error of two perfectly circular mating parts subject to size tolerance for both clearance and transition fit conditions are first developed. The analysis is then extended to nonideal profiles whose profile errors are assumed to deviate from a best-fit circle according to a normal distribution. The assumption of the normal distribution is then removed for more general results via computer simulation. For this purpose, an experimentally verified profile model is used to generate realistic profiles as those produced by various machining processes. Numerous pairs of these realistic profiles are then assembled virtually using Monte Carlo simulation to quantify their positioning errors. The simulation results and the analytical results are compared for cross-checking. Finally, systematic design procedures are proposed to assign circularity tolerance by prescribing a fit condition with a desirable process capability. By the nature of circularity tolerance, this paper addresses a 2D assembly. The result of this 2D analysis can be a foundation for more complicated 3D problems, such as assigning cylindricity tolerance.     

真实环境下产品数据仿真及并行质量优化研究

提出了非正态分布和非对称公差条件下产品最优配合的控制方法。该方法利用数据仿真技术,解决了制造过程的最优质量控制问题。该方法考虑了从产品设计、产品制造到用户使用3个过程产品并行工程问题,是产品精益制造较好的分析控制方法,保证了产品的最终质量。     

冷挤压镦饼毛坯与凹模的配合

将自由镦粗毛坯外径与冷挤压凹模的关系理解为间隙配合，确定了毛坯的基本偏差和公差带。自由镦粗毛坯公差带有特殊的变化规律，毛坯与凹模的基本尺寸（外径与内径）可写成和GB／T1800．1－1997杨似的配合代号。     

Integrated Inspection and Machining for Maximum Conformance to Design Tolerances

Designers' intent for the form, fit and function of products is expressed by design tolerances the conformance to which is the main objective of manufacturing processes. A methodology for maximizing the adherence to the specified tolerances using an integrated machining and inspection system is presented. Considering the desired tolerance envelope of the part, an error decomposition technique is developed to model machining errors caused by the systematic and non-systematic errors in the machine tool. The model is used to adaptively plan the final machining cuts, based on inspection feedback, to enhance the geometric accuracy of the final product and is illustrated by an example. This approach reduces scrap and rework and their associated costs.     

In-process evaluation of workpiece geometrical tolerances in bar turning

This paper presents the development of an on-fine system for the evaluation of workpiece size and geometrical tolerances in bar turning. The measurement is performed using three ultrasonic non-contact proximity sensors which operate in a wet cutting environment. Data conditioning of radius measurements based on spectral analysis and error separation methods are used in order to eliminate errors due to spindle runout and workpiece axis translation. Analytical formulation of cylindricity tolerance is presented. Non-linear numerical optimization techniques are used to fit the data. Two different fitting functions are compared: the least squares and the minimax fit. The sufficiency of the sampled data set is investigated. The determination of cylindricity tolerance of the workpiece from given experimental data is presented and recommendations are given.     

基于Ontology的装配公差规范的自动生成

针对几何产品公差规范设计中存在的不确定性问题,文章将本体理论引入到装配公差规范的设计中,为装配公差规范的自动化、智能化设计提供一种可行的方法。首先构建装配公差规范层次化表示模型,并采用OWL DL断言表示模型层次间的约束关系;其次,根据装配公差规范中的概念和关系,构建装配公差规范的本体模型;再次,根据装配公差规范设计领域的专家知识,使用语义网规则语言(SWRL)构建装配公差规范设计的推理规则;然后,根据构建的本体表示模型及定义的推理规则,构建装配公差规范设计知识库,在此基础上编写装配公差规范智能化设计算法;最后,以齿轮减速器为实例说明了装配公差规范自动生成的过程,并分析验证了该方法的有效性。