热压釜成型复合材料波纹梁工艺工时估算

成本估算是目前复合材料领域开发研究的关键问题之一,而工艺工时估算又是制造成本估算的核心。本文中建立复合材料制造工艺工时估算模型,以热压釜成型复合材料波纹梁为研究对象进行理论分析和实验研究,给出此估算模型中估算变量和方程参数的确定方法并应用最小二乘法将所得数据进行拟合,其结果与实验结果基本一致。介绍了估算模型中参数随制件曲度变化的修正方法,为实现不同结构设计的工时估算提供指导。     

热压釜成型工艺工时估算的理论模型

大部分复合材料新产品的制造成本取决于早期设计阶段,因此应用一个统一的成本估算模型来估算制造成本对设计者来说具有重要的指导作用。针对先进复合材料制造工艺,总结了两种制造工艺时间的估算近似方法:幂定律近似和一级速度反应模型(一阶模型)近似。以热压釜成型工艺生产板材作为实验,应用最小二乘法将所得数据进行幂定律拟合和一阶模型拟合,结果表明,两种方法拟合结果非常一致。一阶模型具有物理可解释性,因此对新的设计和改进工艺,应用一阶模型比较理想。     

复合材料蒙皮加筋壁板结构成本-质量优化设计

介绍了复合材料整体化结构的制造成本估算方法。将成本作为主要的优化设计参,针对蒙皮加筋壁板结构采用共固化成型技术,考虑结构约束及与成型工艺相关的制造约束,提出了在压力和剪切力作用下复合材料蒙皮加筋壁板结构基于成本2质量平衡的优化设计方法。以蒙皮 T形加筋为例,分别选取最小质量和最小成本为优化目标参量验证工时估算模型的有效性。讨论了7种常见形状加筋整体化壁板结构的制造成本和质量,估算值与实验值吻合较好。研究结果表明,蒙皮T形筋制造工时最短而质量仅高于最小质量J形结构的0.5%,是基于成本2质量平衡优化的最佳选择结构。研究结果为复合材料整体化蒙皮加筋结构设计提供指导。     

复合材料结构制造成本估算模型及软件开发

基于制造工艺过程的成本估算模型,采用Delphi 可视化编程语言和SQL server数据库开发工具,开发了复合材料制造成本评估软件。介绍了基于制造工艺过程的成本估算模型的基本特点,重点讨论了工艺时间模型并分析了构件复杂程度对工艺时间的影响。此外,通过引入曲率熵的概念,对前人提出的构件复杂性因子进行了改进,以便更合理地描述构件的复杂度。提出了成本估算软件的总体方案,确定了软件实现流程,并建立了成本数据库管理系统。列举了用该软件对一种复合材料单曲率板的制造成本进行估算的过程。应用所开发的软件对某型飞机的复合材料副翼和金属副翼的制造成本进行了估算,估算结果表明,复合材料副翼由于采用了低成本工艺与整体化的设计理念,其制造成本低于金属副翼。      

复合材料制造成本估算尺寸效应研究

探讨了复合材料制造成本估算的尺寸效应理论,将理论扩展应用于一阶动力学系统、线性控制系统和质点运动模型中。研究结果表明,在复合材料制造成本估算过程中尺寸效应的影响并不是线性的,通过分析不同制件尺寸及不同成型工艺的制造成本,充分验证了尺寸效应理论的可行性。     

基于CAD模型的复合材料机翼成本快速估算

在机翼方案设计阶段需要快速对复合材料机翼的制造成本进行评估。基于制造工艺成本模型开发了复合材料机翼成本估算模型。应用CATIA 二次开发技术编制了模型生成器,实现了参数化建模过程自动化,并为成本模型提供计算所需几何特征信息。实现了机翼设计方案CAD模型与成本分析模型无缝连接的自动化计算过程,给出了实现该过程的流程和主要步骤。以某型无人机复合材料机翼为例,验证了该方法的确能对不同结构布置形式和不同外形的复合材料机翼设计方案进行快速成本评估。估算结果表明,在外形相同的情况下,梁的个数增加1个,肋的个数减少4个的复合材料机翼,其总成本增加了约2.5%;在结构布置相同的情况下,展弦比和梢根比的变化对该复合材料机翼总成本的影响不大。       

基于成组技术的产品成本评估方法

并行工程是一种新的制造思想和生产概念,面向制造的设计(DFM)是并行工程研究的重要内容,成组技术是现代生产技术的重要基础。本文提出采用成组技术的方法,建立基于特征的零件成本评估模型,以对新设计零件进行可制造性评价,从而改进新产品的设计。     

复合材料结构面向成本的设计方法(DFC)

在DFC概念模型的基础上,将面向成本的设计引入复合材料结构设计当中,建立复合材料结构的面向成本设计的理论框架;在对成本估算模型分类的基础上,针对复合材料面向成本设计过程中各个阶段的特点,选择其相应的成本估算方法。     

面向成本的设计方法与技术研究

在分析产品成本相关领域研究的基础上，提出了面向成本的设计方法。根据面向成本的设计方法，在产品概念设计阶段，应用价值工程及ＤＦＡＭ的分析方法，实现产品结构优化。在产品详细设计阶段，通过建立包含制造加工，装配，检测等成本信息的产品模型，实现 技术经济性评价，根据评价结果，及时进行产品再设计，降低产品成本。     

面向DFM评价的制造特征自动获取方法

运用体素分解、体素拼合,自由度分析和加工过程特征等技术,为基于产品设计特征模型的ＤＦＭ评价系统,提供了制造特征自动获取方法,为基于特征的可制造性评价和成本估算奠定基础。     

Automated manufacturability evaluation system for sheet metal components in mass production

Automated manufacturability evaluation of a given design is a key requirement in realizing complete integration of design and process planning. It would still be better to control the designing process itself with manufacturability information. The purpose of such an evaluation is to assist designers in their effort to come up with manufacturable parts economizing in terms of cost and time, without compromising on quality and functional requirements. The present work deals with one such system developed for manufacturability evaluation of sheet metal components. Unlike most of the work done in the sheet metal area in the past, which concentrates on specific domain or phase of manufacturability evaluation, the present work is more comprehensive combining characteristics of all the existing methods and phases of manufacturability evaluation. The prime components of the present system are design evaluation and process plan generation. Design evaluator and process planner use different types of data and knowledge to identify design and process planning violations which are overcome by suggesting design changes. A process planner also uses manufacturing resource and process information to arrive at manufacturable parts by generating feasible process plans. Results of manufacturability evaluation are presented for typical sheet metal parts to be produced by bending and shearing (blanking and piercing) processes.     

虚拟制造环境下成本评估技术

介绍了通过历史成本数据矩阵,寻求最小成本路径,估算最小成本和确定最优工艺路径的方法,为虚拟制造和产品设计提供了有效的决策工具。     

A multi-criteria model for evaluating design for manufacturability

The design for manufacturability (DFM) method is most effective when integrated with the new product development (NPD) process. Due to the focused nature of the associated product and process knowledge and the extensive effort required, there are many NPD situations where classical DFM techniques cannot be readily applied. In this paper, Pro-DFM a multi-criteria model for manufacturability analysis that identifies product realisation opportunities (PRO) for cost reduction is presented. The key assumption in Pro-DFM is that the NPD team has a baseline estimate of production costs, and the evaluation question is how DFM issues will affect the expected unit production cost. The Pro-DFM model analyses a new design in three different factors: part procurement and handling, product assembly fabrication processes, and inventory costs. Each of these is independently analysed using a hierarchy of multiple criteria and sub-criteria. This approach is found to be amenable to most NPD processes, and conducive to easy integration. Each evaluation sub-criterion is presented in the form of a simple query, which is associated with a set of responses that is flexibly anchored to a uni-dimensional scale. A case study example is used to demonstrate the DFM evaluation process and the derivation of the cost penalties.     

Automated manufacturability assessment of rotational parts by grinding

Automated manufacturability assessment of a given design is a key requirement in realizing complete integration of design (CAD) and manufacturing (CAM). The paper deals with a system developed for automated manufacturability assessment by machining processes. The purpose of this system is to assist designers in their effort to come up with manufacturable parts economising in terms of cost and time. Unlike most of the work done in the past, which concentrates on assessment by primary machining processes such as turning and milling, the present work deals with grinding operation. The present system uses geometric reasoning to extract manufacturing specific information from a part model. It uses a knowledge base consisting of grinding process knowledge and control rules, which are activated by the designer. It also has a provision to account for company-specific manufacturing resources to come up with meaningful assessment for part manufacturability. The use of the proposed system is demonstrated for the assessment of axisymmetric parts to be manufactured by cylindrical and internal grinding processes.     

Product Assembly Cost Estimation Based on Artificial Neural Networks

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Design of part family robust-to-production plan variations based on quantitative manufacturability evaluation

This paper presents a systematic method for designing part families whose production costs are insensitive to changes in production plans due to market demand fluctuations. A unified feature-based representation of functional geometry and manufacturability has been developed to manipulate and evaluate part designs. Based on this information and production plans for multiple periods, an optimization-based method provides alternative part designs. The manufacturability of the part designs is quantitatively estimated by the facility cost of the manufacturing system best configured for a given part family and the average cycle time estimated by the discrete event simulation of production scenarios. Redesign suggestions are made on datum definitions of the original parts. Two case studies of a family of prismatic parts and that of turned parts are given to demonstrate the effectiveness of the proposed method. Electronic Publication     

Methods for automated manufacturability analysis of injection-molded and die-cast parts

In this article, a mathematical framework to automatically evaluate the manufacturability of injection-molded and die-cast parts is presented. The framework includes an implemented mathematical algorithm to solve key outstanding challenges in feature recognition for manufacturability analysis of injection-molded and die-cast parts. A novel feature recognition method is developed that is based on decomposing the part into elemental cubes and then, making use of their individual manufacturability, the manufacturability of the part as a whole is evaluated. This article discusses a procedure to obtain a 3D binary representation of the solid model and develops feature recognition techniques to extract critical manufacturability information from this 3D binary array. The outstanding challenges addressed by the method presented include the finding of parting surfaces, parting lines, undercuts, holes, bosses, and finding the direction of mold closure in the context of injection-molded or die-cast parts. The algorithm is implemented using a combination of C++ code and Unigraphics solid modeling software. A short example is presented.     

Rapid tooling manufacturability evaluation using fuzzy-AHP methodology

Rapid tooling (RT) processes driven by rapid prototyping (such as stereolithography and selective laser sintering) can reduce mold development lead-time by 50% or more, though there are certain limitations in terms of mold materials, accuracy, and surface finish. This paper presents a systematic approach for manufacturability analysis of molds produced by rapid tooling methods, based on three aspects: mold feature manufacturability, secondary elements compatibility, and cost effectiveness. The geometric features of functional elements of the mold (core, cavity, side core, etc.) are evaluated for manufacturability using fuzzy-analytic hierarchy process (Fuzzy-AHP) methodology. The secondary elements of mold (parting surface, ejectors, cooling lines, etc.) are checked for compatibility with RT mold properties (machinability, wear resistance, and surface evenness). Finally, the cost of RT mold is estimated using a semi-empirical model based on cost drivers and cost modifiers, and compared with that of a conventional mold. The methodology has been demonstrated with an experimental mold. It is useful not only for RT mold process selection, but also for identifying minor modifications to a mold design to improve its manufacturability and economy.