线性尺寸的公差换算方法

通过实例介绍用非等公差法和等公差法进行线性尺寸的公差换算,既简单又方便,在工程技术中得到了广泛应用。     

极值修正法换算线性尺寸和角度的公差

提出一种极值修正法,它运用公差极值原理,通过角度修正,三角函数计算来正确简捷地换算线性尺寸和角度的公差。     

线性尺寸和角度的公差换算新方法——全微分法

<正> 在机械修理和零件加工、修配过程中,经常遇到线性尺寸的公差换算和角度的公差换算等问题.这类公差的换算过程较繁杂,尤其角度公差的换算很不方便.为了能顺利地解决上述问题.这里介绍一种新的简便方法——全微分法.使用该方法即可使这类公差的换算过程得以简化.又能保证一定的计算精度.颇为实用.下面用两个算例来介绍全微分法.     

线性尺寸分项公差的计算及其修正

在计算线性尺寸的分项公差时，不等公差法和等公差法是解决多尺寸（角度）因素问题的有力工具.但是由于公差传递系数所起的放大或缩小作用，导致计算出的分项公差可能会出现不合理现象，此时应根据加工实际情况对不合理的分项公差进行适当的修正。以实例简洁地介绍了线性尺寸分项公差的计算及修正方法。     

线性尺寸分项公差的计算及其修正

在计算线性尺寸的分项公差时 ,不等公差法和等公差法是解决多尺寸 (角度 )因素问题的有力工具。但是由于公差传递系数所起的放大或缩小作用 ,导致计算出的分项公差可能会出现不合理现象 ,此时应根据加工实际情况对不合理的分项公差进行适当的修正。以实例简洁地介绍了线性尺寸分项公差的计算及修正方法     

极值修正法换算线性尺寸和角度的公差

提出一种极值修正法 ,它运用公差极值原理 ,通过角度修正、三角函数等计算来正确简捷地换算线性尺寸和角度的公差     

工序尺寸换算中假废品的研究

阐述了工序尺寸换算中假废品的产生原因,并通过计算从假废品区内找出工序尺寸放宽的公差带,从而降低了零件的加工难度,又保证了零件的加工质量。     

谈“一般公差 线性尺寸的未注公差”

本文简要介绍了机械加工零件“一般公差线性尺寸的未注公差”,并就如何贯彻应用好线性尺寸未注公差标准谈了一点看法。     

基于特征的公差分析与综合中尺寸链的自动建立

在特征造型基础上阐明了零件和装配体中尺寸、公差的表达和记录，并讨论了尺寸、公差链自动建立的一种方法，以便进行公差分析与综合，使产品成本和精度最佳协调。在产品的三维实体模型上，设计者只需捡取待分析的封闭环的两个端元素，程序就会在零件模型和装配模型中自动搜索建立与此封闭环有关的尺寸链，并确定尺寸链各环的增减性。     

基于模拟退火法的公差并行优化设计

在考虑装配功能要求、加工方法选择、加工余量公差、经济加工精度范围等约束因素的基础上,建立公差并行设计的数学模型,并应用模拟退火法计算.     

计算机辅助公差标准化优化设计的研究

为保证产品实现标准化生产以及实现产品公差的标准化设计,对产品标准化公差与制造成本的建模以及公差标准化算法的实现作了全面深入的分析,提出了具体可行的标准化计算机辅助公差优化设计模型,并提供了应用实例。     

设计尺寸链的计算方法和转换

分析了设计尺寸链的地位和作用;提出利用矢量五步法进行线性尺寸链的分析和计算,并结合工程实例详细说明了如何调整、优化设计尺寸链以到达产品经济性和互换性的目的;同时,根据产品价值链的不同阶段划分,设计完成后的生产制造和检测过程同样离不开尺寸链计算,因此,也对设计尺寸链向工艺尺寸链的转化和换算以满足生产制造需要给出计算实例,并通过尺寸转换使受限制的检测条件亦能验证设计尺寸,从而实现了生产制造的经济性以及高效检测的准确性,即以设计尺寸为基础,通过五步法的简单转换来满足生产制造和检测的需要,确保了设计尺寸在整个价值链中保持恒定不变,从而保证了最终产品的功用和性能。     

The Adaptive Branch and Bound Method of Tolerance Synthesis Based on the Reliability Index

Tolerance synthesis is a stochastic optimisation problem. It can be converted into deterministic optimisation by replacing stochastic design function constraints with deterministic reliability index constraints. This problem was first approached and solved with both a heuristic algorithm TOL-M and a feasible directional method. In this paper, we propose an adaptive branch and bound method, which is a coarse to fine positioning technique, to resolve it. The proposed heuristic algorithm significantly outperforms the previous algorithms for the optimum solution. Although the adaptive branch and bound algorithm is heuristic and does not guarantee a global optimum, we give a theoretical reason why it provides a superior local minimum to both the TOL-M and the feasible directional method. Issues of the relationship between yield and reliability index are addressed. Various related results in the literature are compared with ours to show that some reliability indices are less important than others and can be violated without suffering too much loss of yield.     

Theoretical Tolerance Stackup Analysis Based on Tolerance Zone Analysis

In this paper, both dimensional tolerance stackup and geometrical tolerance stackup in one-, two-, and three-dimensions are theoretically analysed. The tolerance analysis in this study is based on the analysis of tolerance zones. The manufacturing errors are classified into two general types, locating errors and machining errors. Generative formulation of tolerance stackup is explored. A simulation example of 3D geometrical tolerance stackup is illustrated.       

A Statistical Dimension and Tolerance Design for Mechanical Assembly Under Thermal Impact

Most materials change length as they change temperature. As a result of this change, the dimensions and tolerances of a product become at variance with the design values. Hence, thermal effects must be taken into account when designing a product that will undergo temperature cycling. In this regard, a simultaneous optimisation of component dimensions and tolerance values at various temperatures is needed. The approach first generates a set of experimental data through Monte Carlo simulation, based on various combinations of parameters and tolerance levels as inputs. Then, the data are converted into a total cost as response values before applying response surface methodology (RSM) for statistical analysis and optimisation. he response value includes quality loss, tolerance cost, and failure cost, which reflect the combined effect of the parameter and tolerance values assigned. The results provide designers with optimal component parameters and tolerance values, and the critical components and the response function. The approach can also guarantee that the parameter and tolerance values found remain within tolerance for the temperature variation. Then, the product can function as intended under a wide range of temperature conditions for the duration of its life. ID="A1"Correspondance and offprint requests to:Dr A. Jeang, The head of Department of Industrial Engineering, Feng Chia University, PO Box 25–150 Taichung, Taiwan. E-mail: ajeang@fcu.edu.tw     

关于虚公差问题的研究

提出虚公差概念,指出虚公差的意义。在虚公差概念的基础上提出解算带补偿件的尺寸链的概率法,解释了国际GB5847－86为什么对有补偿件的尺寸链不推荐“概率法”的原因。从理论上证明了虚公差概念,对于带补偿件的尺寸链能用概率法来计算,从而为计算机辅助设计装配尺寸链提供了理论依据,同时大大简化了计算机辅助设计装配尺寸链。     

Applying the Coordinate Tolerance System to Tolerance Stack Analysis Involving Position Tolerance

Geometric dimensioning and tolerancing (GDT) has been playing an important role in specifying the geometry of part features during the product design stage. Tolerance stack analysis is then used to study the conformity of the parts to the tolerance zone. Performing stack analysis is time consuming because geometric tolerances are complex to compute. This paper presents a technique to formulate the bonus and shift tolerances (due to positional callout) and convert them to equal bilateral expressions as in a coordinate tolerance system. An example is used to demonstrate the effectiveness of the expressions. The usage of the expressions is less conceptual and this makes the application simple and direct. Most importantly, the results are shown to be accurate and reliable.     

Pro/Engineer平台下装配尺寸链生成的研究

从装配体的装配约束关系中，提取出装配尺寸链上各尺寸所引用的几何元素的装配约束关系。利用这些装配约束关系，按照一定的搜索算法确定各组成环的增减性，计算组成环和封闭环尺寸的大小，生成尺寸链，并得到设计函数。