装配尺寸链的交互式生成和公差遗传优化

研究了一种计算机辅助的交互式尺寸链自动生成方法和基于惩罚函数法的公差遗传优化算法,编制了相应的软件,设计人员可根据装配图,交互式定义并生成装配尺寸链,然后输入公差优化模型,便自动进行公差的遗传优化分配,算例表明,所建立的算法是有效的。     

尺寸公差与形位公差混合优化分配

为解决尺寸公差与形位公差混合优化分配问题,提出了一种公差优化分配方法.根据成本-公差函数和尺寸公差与形位公差的关系,建立了以最小制造总成本为目标的非线性公差混合优化分配模型.该模型的约束包括装配尺寸链的功能要求和加工能力.求解该模型能同时得到优化的尺寸公差和形位公差.最后,分别用公差混合优化分配法和传统方法对一个实例进行公差分配,结果表明所提方法比传统方法更优越.     

CAPP中工序尺寸计算和优化

本文建立一种ＣＡＰＰ系统中工序尺寸链计算的新模型，将工艺过程中各个工序尺寸转换到同一基准上来，简化工序尺寸之间的关系，提出了一种新的工序尺寸公差计算和优化方法，使工序尺寸公差的计算简便可靠，经济合理，并在微机上编制了软件，适用于各类零件长度方向工序尺寸的计算。     

CAPP系统中工序尺寸计算的研究

本文介绍了一种适合于回转体类零件ＣＡＰＰ系统的工序尺寸计算方法，该法根据图解跟踪法的尺寸链原理建立工艺尺寸链，提出了一种新的工序尺寸公差调整方法，使确定的工序尺寸公差经济合理。     

机械产品计算机辅助公差设计方法

运用图论和尺寸链理论,分析了公差设计函数自动生成的机理和实现方法;介绍了尺寸链的建模和路径搜索;指出了确定最佳尺寸链的三个必要条件,尤其是分析了尺寸链标注中的“欠约束”和“过约束”情况及其处理对策,并用实例进行了引证,其结果可应用于机械产品计算机辅助公差分析和公差分配。     

计算机辅助工艺尺寸链计算方法

利用VisualBasic6．0编程工具，根据工艺尺寸链图表跟踪法原理，通过计算机辅助计算方法自动生成工件简图和设计尺寸、工序尺寸及公差、工序余量及公差追踪图，具有友好的人机交互性，提高了工艺设计人员的工作效率。     

浅议最短尺寸链原则与最短测量链原则

1 尺寸链及其计算 在机械制造中,常常需要进行尺寸链的分析计算,从而解决设计中的一些基本问题,如：合理地分配公差,分析结构设计的合理性,校验图纸,正确地进行尺寸标注,以及基面换算和工序尺寸计算等等。 为了满足装配后的最终要求,必须合理地制定各个装配尺寸的公差要求,这就是尺寸链中的反计算,即设计计算的问题。它是将封闭环的公差合理地分配给各个组成环。从另一方面讲,当图样上的各个尺寸设计出来以后,需要验证它们能否保证装配后的技术要求,这乃是尺寸链中的正计算,即验算计算。假若我们要解决的是某一工序尺寸的计…     

套筒类电镀件工序尺寸零与负公差的解决方法

通过对航机套筒类电镀件工艺过程的分析,研究准确合理地应用尺寸链原理计算工序尺寸,确定零件的尺寸公差分配.并提出零、负公差解决的方法.     

应用尺寸链计算杆类电镀件工序尺寸的探讨

通过对活塞杆类电镀件工艺过程的分析,探讨准确合理应用尺寸链计算工序尺寸和尺寸公差分配的方法,并归纳出常用尺寸段电镀件公差表。     

工艺尺寸跟踪图解法的计算机解

一、前言在编制工艺规程、确定工序尺寸时,工厂中一般采用传统的工艺尺寸链方法。由于这种方法未考虑零件加工过程中全部加工尺寸的整体联系,因此它对加工时需多次转换定位基准的精密、复杂零件的工序尺寸、工序公差和加工余量的合理确定带来不便。传统的工艺尺寸链方法计算复杂,常需返工,而采用工艺尺寸跟踪图解法则可扬长避短,简洁明了。本文给出了建立在尺寸跟踪图解法基础上的计算机解。工艺人员只要输入原始参数,计算机就可在两分钟内完成查询公差和余量、寻找和建立尺寸链、校核结果尺寸公差、求解工序尺寸和余量公差等     

Extension of the definition of tolerance and an application thereof in the calculation of dimension chains

When calculating the tolerance of an assembly dimension chain with compensation loop, the value calculated by the basic formula for dimension chains must be a negative or imaginary number; this value is referred to as virtual tolerance in this paper. Virtual tolerance is not covered by tolerance theory. However, after reviewing such relevant concepts such as negative and positive numbers, the essence of virtual tolerance can be defined as follows: the absolute value of virtual tolerance (or the imaginary part) is the error compensation amount and the size between the upper and lower deviations is the compensation range. Therefore, the amount and range of error compensation are both added to the scope of tolerance so that they can be described in a digital way; in the meantime, the range of tolerance is extended to any number. Based on the concept of virtual tolerance, the tolerance and the error compensation amount can be calculated synchronously, leading to a simplified analysis and calculation process; computer-aided design is also facilitated. According to probability theory and the relevant concepts of dimension chains, the only correct result is that the error compensation amount is the imaginary part of virtual tolerance. But since the error compensation amount calculated by the probabilistic method does not ensure assembly accuracy, a theoretical basis is provided to calculate the assembly dimension chain with compensation loop by the probabilistic method.     

A Matrix Method for Calculating Working Dimensions and Offsets for Tolerance Charting

This paper presents a new matrix method for calculating working dimensions and offsets for tolerance charts. The method is part of a more general datum hierarchy tree technique for tolerance planning and control. The matrix method is suitable for both manual and computer-aided computation. It has been implemented in an industrial program, CATCH, and a prototype artificial intelligence (AI) program for process planning. The method has been successfully taught to engineering students in New Zealand and Finland. Worked examples are provided to illustrate the method. The examples show how to calculate working dimensions without offsets, and how to calculate an offset working dimension and an offset resultant dimension.     

Computer-Aided Tolerance Charting for Products with Angular Features

This paper describes a process by which computer-aided design methods are used for the tolerance charting of products with angular features. If a product contains one or more angular features, such as chamfers and tapered surfaces, radial or normal machining of the features will result in axial dimension changes. In this paper, basic trigonometric formulae are first presented to explain the phenomenon of tolerance accumulation. In the process of tolerance charting, dummy cuts are included to reflect the corresponding dimensional changes due to indirect machining. With the assistance of flags and linked lists, the system proposed can automatically identify all dimensional chains which are associated with either regular cuts or dummy cuts. Moreover, optimisation techniques are recommended to allocate the allowable tolerances as specified by blueprints. In the search for an optimal design, the total manufacturing cost defined by the working tolerances is the objective function to be minimised.     

一种设计和工序公差计算机辅助并行设计方法的研究

提出一种计算机辅助设计公差和工序公差并行设计的数学模型，以成本公差函数作为目标函数，以装配功能要求、加工方法、加工余量、工序制造公差范围作为约束条件，并用蒙特卡洛法模拟尺寸装配、模拟退火算法用于优化求解，实现了设计公差和工序公差并行设计，缩短了设计周期。     

An automatic tolerance assignment approach for tolerance charting

There are two dimensional sets in a tolerance chart: the blueprint (B/P) dimensional and the working dimensional group. The interrelation between these dimensional groups makes it very difficult to assign appropriate tolerances to individual working dimensions. This paper deals with the automatic tolerance assignment problem in a tolerance chart, especially for computer-aided tolerance charting. After the manual methods of tolerance assignment are briefly discussed, a linear programming model is analysed. Owing to the impractical solution from the linear programming (LP) model, a proportional smoothing approach is described with a numerical example, which can assign appropriate tolerances automatically and systematically, based on the requirements of both blueprint dimensions and process capabilities. The result from this approach is compared with that of the LP model and the original manual procedure. Finally, the approach is extended to a statistical tolerance model.     

棱柱公差一致性验证技术的研究

分别按照国际中的包容要求、最大实体要求及最小实体要求 ,分析了棱柱形零件尺寸公差和形位公差一致性准则 ,给出了判别一致性的数学等效式 ,举例说明了棱柱公差一致性验证的过程 ,为棱柱形零件计算机辅助公差设计的一致性验证提供了理论方法。     

公差数据库查询系统的设计

运用数据库和软件技术实现多种公差信息的计算机辅助查询,介绍了系统设计的关键问题,运用该系统可提高产品设计和工艺文件编制的工作效率。     

Tolerance control for dimensional and geometrical specifications

The development of tolerance charts has come a long way from the past manual methods to the current computer-aided models. As a result, many techniques have emerged over the years. However, the area of geometrical tolerance charting has not been given much attention. In view of this, this paper addresses both linear and geometrical tolerance control.The method proposed in this paper allows the user to construct a model directly from the process plan. The relevant process links between any two planes which are required to satisfy both the linear and geometrical requirements are easily obtained from the model. Having established all the appropriate constraints, the linear programming optimisation software is used for the determination of the unknown working dimensions and tolerances.In essence, this paper presents a new methodology for deriving the process links from the process plan and also highlights the significance of the use of linear programming in achieving the optimal tolerance mix or combination.     

Review: geometric and dimensional tolerance modeling for sheet metal forming and integration with CAPP

The focus of this publication is a review of the state of the art in tolerance analysis, synthesis, and transfer for geometric and dimensional tolerances in sheet metal forming and the integration solutions with computer-aided process planning systems. In this context, the general tolerance methods are first described. Then, the mathematical models for sheet metal tolerance analysis and synthesis are examined in detail. To address the CAPP modeling concerns, the paper is then followed up with a brief review of past research works related to feature-based process planning. Finally, those imperative future research areas are identified.