面向制造环境的稳健公差设计方法

提出一种基于制造环境的稳健公差设计方法，使得在公差设计中能考虑实际加工环境即各种加工方法的工序能力，从而保证在获得最优稳健公差的同时选择合适的加工方法，以保证设计公差的可制造性和稳健性，提高产品的设计质量。     

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。     

基于工序能力的公差统计分析方法的研究

介绍了公差分析中的工序能力和工序能力指数,分析了工艺误差为正态分布、工艺误差均值漂移分别为均匀分布和正态分布时尺寸误差的统计特性,给出了装配特性的统计公差分析结果,举例说明了该公差分析方法的应用过程.     

基子工序能力的公差统计分析方法的研究

介绍了公差分析中的工序能力和工序能力指数，分析了工艺误差为正态分布、工艺误差均值漂移分别为均匀分布和正态分布时尺寸误差的统计特性，给出了装配特性的统计公差分析结果，举例说明了该公差分析方法的应用过程。     

某型手枪击发机构装配公差分析与信息化集成研究

针对轻武器行业"人工修锉"问题和企业数字化设计与制造需求,利用VSA软件进行了某手枪击发机构三维装配公差分析,得到了与实际装配情况一致的结果,说明基于三维模型的计算机辅助公差设计技术适用于轻武器设计制造公差控制,在轻武器数字化设计制造过程中可以为实际设计、制造提供支持,减少工程更改。在此基础上提出了CAT在数字化协同设计和制造环境下系统信息化集成框架、应用模式、数据模型和数据交互方式等,为后续系统的开发、集成与应用提供了参考。     

基于有限元模型的汽车薄板焊装公差分配研究

当前的汽车车身薄板覆盖件焊装公差分配方法,通过收紧装配公差以期达到车身焊装高的质量要求,而公差过小不仅提高了制造成本,还往往超出了装配件制造能力。本文提出一种基于有限元模型的公差分配方法用于薄板装配,利用该方法可在装配前确定满足产品整体质量要求的最大允许加工公差,这样既可以降低装配件制造成本,又可以保证车身焊装的质量。此方法为汽车薄板件冲压工艺设计提供了依据。     

基于工序加工能力的并行公差优化设计

提出一种基于工序加工能力的并行工序公差优化设计方法。在产品的初步结构设计阶段，通过相配零件的加工工艺规划把装配功能公差表示为零件的工序公差，建立以加权制造总成本最小为目标，以并行公差链、标准化的工序公差系数、机床最大经济极限公差为约束的非线性并行公差优化设计模型，求解该模型得到最佳的工序公差。最后给出了并行公差优化设计的一个工程实例，结果表明，所提的方法具有比传统串行等精度方法更合理、工序公差数值更大的优点。     

基于多重相关特征质量损失函数的并行公差设计

基于多变量质量损失函数,推导了多重相关特征产品的质量损失与有关零件工序公差的函数关系,建立了基于制造成本-质量损失的并行公差设计的优化综合模型,其目的是寻求制造成本和质量损失之间的平衡,以实现相关特征产品的设计公差与工序公差并行优化分配,达到提高产品质量和降低成本的目的。圆锥齿轮装配的并行公差设计实例验证了所提方法的有效性。     

基于信噪比多元质量损失和制造成本的并行公差设计

质量损失是由于产品的功能波动所造成的,损失大小可由质量函数确定。在无量纲“标准化”多元质量损失函数的基础上,采用信噪比衡量各质量指标的波动,建立一般情形下的基于信噪比的多元质量损失模型,并把它表示成多个相关装配尺寸产品的工序公差函数。利用成本-公差函数和产品质量损失函数,给出基于产品最低制造成本和多个相关装配尺寸产品质量损失的并行公差设计优化模型,实现公差的并行设计,最后通过工程实例验证所提出的方法。     

基于制造成本与质量损失的并行公差设计

研究产品质量损失与产品尺寸公差的关系 ,提出具有多个相关装配尺寸产品的质量损失 ,并把它表示成工序公差的函数。利用成本 -公差函数和产品的质量损失函数 ,给出基于产品最低制造成本和多个相关装配尺寸产品质量损失的并行公差设计优化模型 ,实现公差的并行设计 ,最后通过工程实例验证所提出的方法     

Concurrent optimization of machining process parameters and tolerance allocation

With the advent use of sophisticated and high-cost machines coupled with higher labor costs, concurrent optimization of machining process parameters and tolerance allocation plays a vital role in producing the parts economically. In this paper, an effort is made to concurrently optimize the manufacturing cost of piston and cylinder components by optimizing the operating parameters of the machining processes. Design of experiments (DoE) is adopted to investigate systematically the machining process parameters that influence product quality. In addition, tolerance plays a vital role in assembly of parts in manufacturing industries. For the selected piston and cylinder component, improvements efforts are made to reduce the total manufacturing cost of the components. By making use of central composite rotatable design method, a module of DoE, a mathematical model is developed for predicting the standard deviation of the tolerance achieved by grinding process. This mathematical model, which gives 93.3% accuracy, is used to calculate the quality loss cost. The intent of concurrent optimization problem is to minimize total manufacturing cost and quality loss function. Genetic algorithm is followed for optimizing the parameters. The results prove that there is a considerable reduction in manufacturing cost without violating the required tolerance, cutting force, and power.     

Tolerance design of mechanical assembly using NSGA II and finite element analysis

The technological and financial limitations in the manufacturing process are the reason for non-achievability of nominal dimension. Therefore, tolerance allocation is of significant importance for assembly. Conventional tolerance allocation methods are limited by an assumption that all parts are rigid. Every mechanical assembly consists of at least one or more flexible parts which undergo significant deformation due to inertia effect. Finite element analysis is used to determine the deformation of components in an assembly. Therefore, integration of statistical tolerance design with finite element analysis will guarantee that the optimal tolerance values of various components of the assembly obtained as end product of the tolerance design will remain within tolerance variation. Then the product can function as intended under a wide range of operating conditions for the duration of its life. In this paper, tolerance design of a piston cylinder assembly is done to demonstrate the proposed methodology.     

Manufacturing environment-oriented robust tolerance optimization method

Tolerance design has a great impact on the cost and quality of a product. Previous research focused on process tolerances or robust tolerance design with little consideration on real manufacturing context. This paper presents a nonlinear method for robust tolerance design based on the real manufacturing context in three stages. The objective function to be minimized is the total manufacturing cost. The constraint equations for the optimization model are also deduced, which select suitable manufacturing processes based on the manufacturing environment. Simulation annealing (SA) is used for the nonlinear optimization. The approach is finally illustrated by a practical example. The results of the comparison with different models indicate that the proposed approach is more effective with the manufacturing resource. The robust and reliable tolerance can be obtained.     

基于宽容分层序列法的飞机装配公差稳健设计技术

飞机制造中由于工序能力指数和公差等设计变量存在变差,可能导致无法满足飞机装配质量要求以及制造成本波动较大的问题。运用稳健设计方法建立了飞机装配公差的可行稳健性和敏感稳健性两类设计模型。可行稳健设计考虑了公差等设计变量对装配可行性的影响,使其变差不影响装配功能的实现;敏感稳健性设计则考虑了公差等设计变量对制造成本和装配质量的影响,在目标成本较小的前提下使得目标成本和装配质量受设计变量变差的影响最小。提出了针对飞机装配公差可行敏感稳健设计的多目标优化问题的宽容分层序列求解算法。将公差设计中制造成本、装配质量波动、制造成本波动多个设计目标按照重要性依次排序。首先求解成本最小情况下的公差一般优化解,然后在成本最小值的宽容约束下,求得具有装配质量波动最小值的公差,最后在上述两个优化目标的宽容约束下,求得成本波动最小的最优公差。应用实例和分析结果表明了方法的有效性。       

Tolerance allocation of assemblies using fuzzy comprehensive evaluation and decision support process

Tolerances play an important role in product fabrication and have a significant impact on manufacturing costs. The factors affecting manufacturing cost (geometry, material, etc.) of a part are fuzzy or subjective in nature since they have no appropriate numerical measure. This paper proposes a framework that overcomes the drawbacks of traditional tolerance control methods and reduces subjectivity via fuzzy comprehensive evaluation and conjoint analysis. In the fuzzy comprehensive evaluation process, the relationship between the machining costs and part tolerance is expressed through a mathematical formula, with the objective of minimizing the total machining cost. The conjoint analysis method is introduced to provide a systematic method of deciding weights for each of the factors in the tolerance allocation procedure. The application of the framework is demonstrated with practical engineering problems of allocating tolerances of an accumulator’s O-ring seal and a clutch assembly.     

基于广义装配原理的产品生长型设计

通过研究生物生长与产品设计之间的相似性,提出了基于广义装配原理的生长型设计过程,研究了广义装配原理的三个理论构成。首先,在产品生长阶段,为实现生长过程中的自然选择,提出了以复杂度理论为控制因素的设计推理策略;其次,提出了功能公差设计理论,通过加工成本以及基于多因素的模糊质量损失成本体现广义装配成本,在确保产品功能的同时,以较低的装配与制造成本为公差的分配策略;在产品进化阶段,为保证产品良好的装配性能,采用了虚实结合设计技术。将以装配质量因素为核心的产品复杂度、精度以及制造、装配成本等众多设计因素并行集成于生长型设计过程中,实现了以全生命周期装配质量保障为核心的产品生长型设计。     

Optimal tolerance allocation for precision machine tools in consideration of measurement and adjustment processes in assembly

The high geometric accuracy requirement of precision machine tools represents a challenge for tolerance design and assembly process planning that guarantee the final assembly accuracy. Component tolerances should be allocated in association with assembly processes. However, tolerance design and assembly process planning are usually considered separately and lack quantitative analysis. In this paper, to integrate the geometric tolerance of components and variation propagation in assembly process, a state space model is developed. The measurement and adjustment process are expressed as observation matrix and control inputs. An optimal control problem is formulated to determine the adjustment process in consideration of the loss of final assembly accuracy and costs of remachining adjustment process. Tolerances of components can be optimally allocated based on the variation propagation in this deterministic assembly process. The generality and effectiveness of this approach are validated by applying the model on a four-axis horizontal machining center.     

Cost drivers-based method for machining and assembly cost estimations in mould manufacturing

Dies and moulds represent an essential element in manufacturing process and significantly influence the fabrication time and cost of the products. Moreover, the market continuously asks the die manufacturers for products that have better characteristics in terms of finishing, complexity or flexibility within a reduction of the time to market and cost, so as to follow the rapid changes in the product design. Therefore, in order to give to the customer the best cost-performance solution, companies require accurate and reliable tools for die manufacturing cost estimation both for commercial purposes and for comparisons amongst different design solutions. In this context, the paper proposes a method for manufacturing cost estimation based on the definition of cost drivers. The method was implemented using a database coming from a company specialized in the production of dies for sheet forming and rubber injection and it allowed to estimate a cost estimation relationship (CER) function that is able to correlate the cost drivers with the manufacturing cost of machining and assembly phases. In particular, the method allowed to overcome the limitations related to the available data as the company's own storage criterion, unbalancing and high and non-uniform scattering that do not allow use of the variance analysis technique.     

基于DFA和DFC的综合公差优化

公差是机械设计和制造过程中最重要的参数之一,其对加工成本和产品质量有很大的影响。本文采用 DFA和DFC的综合方法对制造过程中的装配精度进行分析和综合,建立了以公差为主的成本信息模型,对设计公 差和加工公差进行了系统分析,以最低制造成本为目标,根据成本 公差间的函数关系,建立了非线性的公差优化模 型,并采用遗传算法使这一问题得到了很好的解决。实例证明该方法是可行的。并为并行工程实施中其他的DFX 与DFC结合实现制造成本最低提供了良好的解决方案。