设计图样中形位公差的合理确定

文章针对设计图样上经常出现的形住公差选择不恰当问题展开了讨论。论述了尺寸公差与形住公差之间的关系；位置公差与形状公差的关系；综合公差和单项公差的关系；以及形位公差值的选用原则等。     

零件尺寸与尺寸公差集成变型设计方法

为了解决产品变型设计中尺寸公差设计问题,提出了一种基于参数化技术的零件尺寸与尺寸公差集成变型设计方法.给出了零件尺寸变型设计的基本原理和方法.通过分析传统公差的设计方式,将尺寸公差随其作用尺寸变化的情况分为公差值不变、公差精度等级不变和公差值按特定规则变化三种,并给出了在这三种情况下尺寸公差随其作用尺寸变化的规律.给出了零件尺寸与公差集成变型设计方法的具体步骤.开发了与SolidWorks集成的零件尺寸与公差集成变型设计模块.最后,以减速器输出轴为例对所提方法和模块进行了验证.     

矩阵法求解尺寸及公差

提出了一种在机械加工工艺过程中用于计算尺寸及公差的方法,矩阵法。它只需要按照简单规则进行相应加减计算,并依照既定的方法进行追踪,最后在矩阵表中布置即可。不必作图,也不必进行尺寸链的解算,便可得到加工后各表面的尺寸及公差。详述了此法的原理及过程,并用拖拉机上的差速器做了详尽说明。与传统的图表追踪法、图论法相比,矩阵法在处理轴向尺寸链解算方面更胜一筹。由此可知,此法对今后尺寸链的解算具有一定推广意义。     

Dimensional and geometric tolerance design based on constraints

The paper presents a computer-aided approach of dimensional and geometric tolerance design. The method allows a designer to specify synthetically dimensional and geometric tolerances, including tolerance types and values. Firstly, tolerances are classified as self- and cross-referenced tolerances, and the rules for tolerance types design are presented. Secondly, the stack-up of 3D feature variation is formulated as a set of stack-up constraints (equation constraints), and the variation specified by tolerance forms tolerance constraints (inequality constraints). Tolerance value design is represented as the combinatorial optimization problem. The application of the variation and tolerance constraints to specify tolerance values is studied. Finally, a tolerance design example is used to illustrate the method.     

Study and evaluation of fretting critical slip conditions by applying the design of experiments method

Tribological systems are complex systems that require a multi-disciplinary (mechanical, material, physico-chemical) approach where numerous influence factors can be involved. To characterize a contact couple, the intrinsic parameters of the materials as well as the parameters related to the contact loading and the surrounding environment need to be taken into account. Fretting analysis, by means of running condition-fretting maps (RCFM), allows the behavior of the contact couple to be taken into account and to predict the boundary between partial slip and gross slip conditions. This article presents the study of a steel/polycarbonate couple during fretting tests. The study was carried out by performing a complete factorial experiment. This method has the advantages of reducing the number of experimental trails and of obtaining the internal laws of dependence, which highlight the influence of the significant factors of the fretting process on the tribological behavior of the studied contact couple.     

基于装配尺寸式的复杂装配体形位公差设计

以圆盘剪为例,按装配尺寸式原理找出影响圆盘剪上下刀盘剪切质量的各个零件的位置关系,再按照等精度原则对相关零件的形位公差进行分析计算,从而确定出圆盘剪各相关零件的形位公差,经生产验证,该方法确定的形位公差可以满足圆盘剪的精度要求     

一种面向热膨胀性能的公差设计方法

双材料点阵是实现热膨胀设计最有效的途径之一,然而制造误差会对热膨胀性能造成影响,传统公差理论无法保证产品性能的精确实现。提出了一种能保证双材料点阵等效热膨胀系数精确实现的功能性公差设计方法。首先,分析尺寸的热膨胀效应,根据结构热膨胀性能的极限情况进行变量分组;然后,分析尺寸敏感度,分别采用逐步降低敏感尺寸的公差等级和优先降低非敏感尺寸的公差等级两种方法对尺寸偏差优化模型进行改进;最后,通过对三种热膨胀性能的胞元进行公差设计,验证了方法的正确性。本文首次考虑了双材料结构的公差设计,建立了公差设计和结构热膨胀性能之间的关系,对双材料点阵的制造与应用具有很大的理论和实际意义。     

三维CAD中几何公差自动判别技术研究

针对目前在三维CAD系统中,几何公差的标注由人工基于经验知识完成,错误的标注无法得到自动纠正的问题.根据国家标准中几何公差定义,建立基于几何要素的公差判别路径图--"几何公差树",以此进行几何公差标注的自动判别,从而规范几何公差的标注操作,并在SolidWorks软件中实现对示例对象的几何公差标注自动判别功能.     

多工序尺寸及公差优化

为提高产品制造质量、降低产品制造成本,提出了一种多工序尺寸及公差的优化方法.该方法综合考制造成本、质量损失和加工能力指数,以加工能力指数分别修正制造成本一公差函数和质量损失函数,在工序内建立总成本一公差函数模型.在此基础上,采用目标层解法优化特征内的各个工序基本尺寸和尺寸公差,最终达降低特征总成本的目的.最后以一个仿真实例验证了该方法的可行性.     

Optimal geometric tolerance design framework for rigid parts with assembly function requirements using evolutionary algorithms

A new forming technology of car steering knuckle was presented, aiming at eliminating the defects in the existing steering knuckle forming process. Based on orthogonal experimental design to numerical simulation by using FEM, for steering knuckle closed extrusion of multi-objective optimal design problems in systematic research, the influences of extrusion temperature and speed, mold temperature, and lubrication of forming technology were discussed with comprehensive scoring method and integrated balance method, then the process parameters used in the forming were applied in the productive practice. Results show that the orthogonal test method combined with finite element simulation can be flexible and efficient in handling of multi-objective optimization problems. As for the forming of other types of long rod fork forging, the new process and the design method have important guiding significance.     

基准遵循最大实体要求时的几何要素检验方法

为了进行零件的几何误差检测以提高零件的合格率,提出一个通用的基准偏差量的表示和补偿方法。利用模拟基准要素概念,确定实际状态下模拟基准要素和最大实体状态下基准要素边界之间的相对位置关系,获得最大实体状态和零件实际状态的基准参考框架之间可能存在的相对位置变化范围。对遵循最大实体要求的圆柱基准和直槽基准的两个基准组合,采用曲柄导杆机构和摆杆机构的组合机构表示相对位置关系,曲柄长度和摆杆摆角就是两个基准偏离其最大实体状态的偏差量,曲柄长度对应被测目标要素的几何公差值的补偿量,而摆杆摆角则对被测目标要素的公差带的形状同时进行了修改和扩大。以一个成组要素的位置度误差检测为例说明了具体实施方法,并讨论了应用最大实体要求的基准本身的精度等级设置关系。     

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.     

基于遗传算法的深沟球轴承优化设计研究

给出了基于遗传算法的深沟球轴承优化设计的方法。针对传统算法在深沟球轴承优化设计中全局寻优能力较差问题,以标准遗传算法（Genetic AlgorithmGA）的算法参数,采用了最优解保存策略,并运用罚函数法处理约束。为了降低摩擦阻力和减轻磨损,减少发热量,针对轴承发热变形的一个主要因素摩擦进行建模。     

SolidWorks中公差与符号标注的二次开发

主要介绍了以VB为开发工具,用Microsoft-ACCESS2000建库,利用Solidworks OLE应用程序开发接口API函数实现Solidworks中尺寸公差查询和符号标注模块系统的研究和开发。该模块解决了Solidworks中不能动态查询尺寸公差和符号标注的问题。     

Unified dimension and tolerance modeling for mechanical precision predicting

Precision predicting is significant for quality qualification of complicated product, and it is one of the fundamental applications for virtual assembly system. For most predicting methodologies, functional precision is propagated by both dimension and geometric tolerance; however, dimension and geometric tolerance have different manifestation patterns that relay on traditional GD&T standard, and it brings difficulty in considering dimension and geometric tolerance simultaneously; hence, a uniform model called maximum compatible constraint model (MCCM) is proposed. Dimension and geometric tolerance are clustered into three types: deterministic constraint, micro-degree constraint, and release constraint. The MCCM model explains these multiform constraints with unified constraint matrix, dimension torsor (D _mT ), and deviation torsor (D _vT ). D _mT is introduced to record the ideal position of functional geometry referring to geometry coordinate system. D _vT and micro-degree variational zone are discussed for explaining variational information of precision; in addition, topological structure related to functional and datum surfaces are extracted. By compatible structure, MCCM is not only adaptable for explaining dimension and geometric tolerance, but also for modeling geometric and assembly constraints that are meaningful for variation propagation during assembly process. With all constraints, dimension and tolerances are modeled, and then MCCM set is attained. Within the MCCM set, dimension cumulative, variation, and error propagation are facilitated by constraint and direction discussion, and precision predicting is conducted more specifically.     

工艺尺寸式及其方法

本文提出了一种非常适合计算机辅助工序尺寸设计的工艺尺寸式法，并简要介绍了工艺尺寸式原理及工艺尺寸关系的查找方法。通过实例说明，工艺尺寸式与工艺尺寸链相比具有不需绘图，不易出错，寻找工艺尺寸关系方便，理论完善，通用性强等特点，指出用工艺尺寸式代替工艺尺寸链无论对教学还是对生产实际都有重要意义。     

公差可行稳健设计及其评价方法研究

公差可行稳健设计对于提高产品的质量起着重要的作用。在公差可行稳健模型的基础上,提出基于两步法和直接优化法的公差可行稳健设计法,针对约束函数为线性函数和非线性函数,采用基于重点抽样方法(MPP)进行装配成功率的估算,实现了对公差可行稳健性的评价。最后用实例进行验证。     

基于自由度变动的几何公差分析模型

公差数字化分析与综合理论是现代计算机辅助公差(CAT)发展的关键环节之一.在自由度变动法基础上阐述了几何公差的分析原理,并且提出了对同一特征多种公差要求等若干具体情况的分析方法和空间误差积累的计算流程.     

Stewart平台式六维力测量装置研究与设计

:利用Stewart平台结构特点 ,开发一种新型的六维力测量装置。根据Stewart平台的静力学关系 ,建立了六维力测量装置的数学模型。给出了Stewart平台上平台所受的六维力和 6个支承腿所受拉压力的关系 ,并进行了结构设计和测量系统设计     

振动筛用多种强迫激振运动激振器几何条件的确定

由曲线论的基本公式和刚体运动学的理论，推导出了多种强迫激振运动激振器，能使振动筛实现直线、圆和平动椭圆运动规律的几何条件。结论认为，只要该激振器的单行星齿轮机构中，齿圈和行星轮齿数比为2：1时，通过调整行星轮上的偏心块的位置，就可在同一振动筛上方便地实现多种振动运动。