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.     

生长型设计中的功能公差设计理论

在产品结构设计自动化技术基础上,研究生长型设计中公差进化设计的策略与原则,提出将产品功能要求转化成零部件之间的几何约束关系,并最终表达为对功能尺寸约束的功能公差设计理论。建立成本—公差敏感函数的数学模型,将产品设计、制造、使用以及技术折旧成本作为公差分配的控制约束,并在其中引入产品使用磨损模型,以经济学中的贴现率来表征技术折旧成本,以成本最低为目标函数,以合理的工艺能力指数、装配功能、装配质量作为约束条件,实现基于功能与成本的面向产品全生命周期的尺寸公差分配。最后,设计实例说明所提出的功能公差设计理论能够在生长型设计中成功应用。     

生长型设计中的复杂度设计策略

通过对生物进化复杂性与产品复杂度的对比,提出了生长型设计中的复杂度设计策略,定义了描述产品基因复杂性的分类指标,给出了描述产品基因单元自身约束复杂度的单元复杂度,以及描述进化设计每一阶段产品各组成单元总体复杂度的种群复杂度.应用信息熵,建立了定量评价产品复杂度的数学模型,给出了产品功能信息量、几何结构信息量、装配复杂度、制造复杂度的量化方法.最后,为实现生长过程中的自然选择,通过对产品基因的多级分解,提出了以复杂度为控制因素的产品组成单元的进化策略.     

生长型设计中公差进化设计方法研究

为实现生长型设计中尺寸链及形位公差项目的自动生成,在产品结构设计自动化技术基础上,研究生长型设计中公差进化设计的策略与原则。指出生长型设计中紧随结构的自顶向下、不断进化,公差进化设计模型也呈现为一种层次式结构;同时由于功能表面及其名义特征所具有的承载功能及几何信息的特点,可作为公差进化演绎的单元载体;在此基础上建立公差进化设计的基本过程模型。提出产品结构进化设计中,构建基于功能表面的装配网络以及基于名义特征的约束网络的双层装配约束网络的基本方法,给出辅助公差进化设计的公差断言;在此基础上,给出基于双层装配约束网络及公差断言的尺寸链及形位公差进化设计的基本过程。以活塞精镗销孔夹具的公差设计为例,说明所提出的公差进化设计方法在生长型设计中的成功应用。     

基于灰色粒子群算法的飞机装配公差多目标优化设计

为全面考虑公差对制造成本的影响,将装配成本引入飞机装配公差优化设计模型,针对典型的飞机装配工艺方法,提出一种基于制造成本和质量损失的公差多目标优化设计模型,进而实现不同装配方法约束下的公差优化设计。将灰色关联理论与粒子群优化算法相结合应用于公差优化设计,根据公差设计特点提出改进策略,使其能够有效实现模型的求解。以某飞机典型组件为例,验证了该方法的有效性,并对不同装配方法的公差设计结果进行了对比分析。     

多工位装配过程夹具系统公差和维护综合优化设计

提出一种面向二维多工位装配过程、综合考虑装配夹具系统全寿命周期成本、产品零件孔制造成本和产品质量损失成本的公差和维护综合优化方法。分析多工位装配尺寸偏差传递关系,建立多工位装配过程产品质量损失模型。然后根据4-2-1夹具定位原则,构建考虑夹具磨损过程损失的夹具定位销副偏差统计数字特征模型。继而发展了以夹具系统全寿命周期成本、零件孔制造成本和和产品质量损失成本为装配总成本最小化的定位销公差、零件孔公差与更换周期优化模型。以汽车侧围装配过程为例,分别研究定位销公差、零件孔公差、定位销更换周期、配合间隙、平均磨损率和磨损率方差对装配总成本的影响,并优化设计定位销公差、零件孔公差和定位销更换周期。所提出的综合优化设计方法比采用定位销等公差设计、零件孔等公差设计、定位销与零件孔等公差设计和定周期更换设计的装配总成本分别减少了16.25%、11.31%、39.93%和13.54%。该方法为产品装配夹具系统高质量低成本设计提供了一种新的途径。     

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。       

再制造公差设计优化模型及其应用

为降低再制造产品的成本,保证和提高产品质量,将公差设计方法引入再制造工程。在深入分析再制造公差设计特点和公差分配原则的基础上,提出了一个再制造公差设计的优化数学模型。该模型以统计公差原理为基础,以再制造总成本最低为目标,综合考虑了保证和提高产品性能、表面工程技术、过程能力指数等制约因素,在质量成本中的田口质量损失成本的基础上增加了质量保证成本。结合某企业ZQDR-410型牵引电动机的再制造案例,对传统再制造方案和所提方案进行了比较,证明了该公差设计优化模型的有效性和实用性。     

并行和协同设计中的变动约束管理方法研究

设计和制造企业多试图同时增加产品的复杂度、减少设计周期、降低产品成本和改善质量。减少成本而又不破坏产品质量的一个很好的使能工具是控制设计和制造过程的变动。本文从并行工程和协同设计的角度出发 ,阐述了产品开发过程中的变动及其管理 ;研究了面向装配、制造和产品性能的变动约束网络的构建 ;给出了面向并行工程和协同设计的变动约束管理的方法 ,以有效地支持参数与公差设计 ;并通过实例分析给予了验证     

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。     

Functional tolerance theory in incremental growth design

The evolutionary tolerance design strategy and its characteristics are studied on the basis of automation technology in the product structure design. To guarantee a successful transformation from the functional requirement to geometry constraints between parts, and finally to dimension constraints, a functional tolerance design theory in the process of product growth design is put forward. A mathematical model with a correlated sensitivity function between cost and the tolerance is created, in which the design cost, the manufacturing cost, the usage cost, and the depreciation cost of the product are regarded as control constraints of the tolerance allocation. Considering these costs, a multifactor-cost function to express quality loss of the product is applied into the model. In the mathematical model, the minimum cost is used as the objective function; a reasonable process capability index, the assembly function, and assembly quality are taken as the constraints; and depreciation cost in the objective function is expressed as the discount rate—terminology in economics. Thus, allocation of the dimension tolerance as the function and cost over the whole lifetime of the product is realized. Finally, a design example is used to demonstrate the successful application of the proposed functional tolerance theory in the incremental growth design of the product. __________ Translated from Chinese Journal of Mechanical Engineering, 2006, 42(10): 73–79 [译自: 机械工程学报]     

基于产品基因分解重构的生长型设计

将基因工程思想用于产品的进化设计过程，通过对产品基因的多级分解提出了产品组成单元的进化策略。在给出基于功能约束的产品基因分解数学模型的基础上，将装配复杂度及制造复杂度作为有效的控制约束引入其中，得出了产品基因的最优划分策略，在此基础上提出了基因重构方法。用滚子夹具设计实例验证了设计方法的有效性。     

Tolerance evolutionary model and algorithm in product growth design

To guarantee the successful transformation from product functional requirement to geometry constraints and finally to dimension constraints between components in a product, an evolutionary tolerance design strategy is proposed on the basis of automation technology in product structure design. In the first part of this paper, the theory of the growth design and the process of tolerance evolutionary design are introduced. Following the evolution of product structure, product tolerance grows from its initial state, defined by accuracy requirements, to its final state, defined as dimension tolerance and geometric tolerance. In this growing process, the basic units in the product growth design, known as functional surfaces and their nominal features, are used as evolutionary carriers. With the help of these basic units, the method for the construction of a two-layer correlation network is proposed. In the second part, the tolerance assertions to assist tolerance evolutionary design are given, based on which the basic process for an evolutionary design of dimensions chain and geometric tolerance are presented. In order to optimize the allocation of the dimension tolerance, a mathematical model is developed in which a correlated sensitivity function between the cost and the tolerance is created. In the model, the design cost, the manufacturing cost, the usage cost, and the depreciation cost of the product are used as constraints to the tolerance allocation. Considering these costs, a multifactor cost function to express quality loss of the product is developed and is applied into the model. The minimum cost is used as the objective function, and the depreciation cost in the objective function is expressed by the discount rate—terminology in economics. The aim was to achieve a final and ideal balance around assembly, manufacturing, and usage through the control of product precision. In the last part, the successful usage of the proposed tolerance evolutionary strategy in the incremental growth product design is demonstrated through a design example.     

公差稳健优化设计的研究

为了解决产品加工成本与质量稳健的协调性问题,提出了一种新的公差稳健优化设计数学模型.依据公差稳健设计的思想,考虑产品质量的模糊性,以封闭环误差分布概率密度函数的方差和优质品概率之比为设计目标,建立了公差优化设计产品质量稳健性损失成本目标函数,并研究了优质品率和封闭环误差分布方差的确定方法.以加工成本和产品质量稳健性损失成本为目标,以模糊装配可靠度、可取公差极限范围为约束条件,建立了公差多目标优化数学模型.举例说明了文中所述的公差稳健优化设计方法的应用,采用遗传算法实现了公差的多目标优化设计.实例表明,该方法能够协调零件的加工成本和产品质量的稳健性损失成本,使优化指标的综合性能最佳.     

Optimal tolerance design of assembly for minimum quality loss and manufacturing cost using metaheuristic algorithms

Tolerance allocation is a design tool for reducing overall cost of manufacturing while meeting target levels for quality. An important consideration in product design is the assignment of design and manufacturing tolerances to individual component dimensions so that the product can be produced economically and functions properly. The allocation of tolerances among the components of a mechanical assembly can significantly affect the resulting manufacturing costs. In this work, the tolerance allocation problem is formulated as a non-linear integer model by considering both the manufacturing cost of each component by alternate processes and the quality loss of assemblies so as to minimise the manufacturing cost. Metaheuristics techniques such as genetic algorithm and particle swarm optimisation are used to solve the model and obtain the global optimal solution for tolerance design. An example for illustrating the optimisation model and the solution procedure is provided. Results are compared with conventional technique and the performances are analysed.     

Concurrent tolerancing for design and manufacturing based on the present worth of quality loss

The quality loss function developed by Taguchi provides a monetary measure for the deviation of the product quality characteristic from the target value. Product use causes degradation on its quality characteristic, and since such a deviation can be changing over time, so can the quality loss. However, most studies on concurrent tolerancing theory do not consider the quality loss caused by the degradation. In this paper, the present worth of expected quality loss expressed as the function of the pertinent process tolerances in a concurrent tolerancing environment is derived to capture the quality loss due to product degradation over time as a continuous cash flow function under continuous compounding. A new tolerance optimization model, which is to minimize the summation of manufacturing cost and the present worth of expected quality loss, is established to realize the concurrent tolerance allocation for products with multiple quality characteristics. An example of the bevel gear assembly involving concurrent allocation of design and process tolerances is given, demonstrating that the proposed model is feasible in practice.