汽车覆盖件冲压工艺设计KBE系统中的知识表示技术

根据汽车覆盖件冲压工艺设计的特点,阐述了与汽车覆盖件冲压工艺设计有关的不同类型知识的表示方法,主要有一阶谓词逻辑、语义网络、产生式规则、框架和剧本、可视化文本和图象,以及面向对象的方法等,并比较了各种方法的优缺点.面向对象的集成知识表示等方法成功地应用于汽车覆盖件冲压工艺设计KBE系统的知识表示.     

汽车覆盖件冲压方向目标函数权重研究

确定以参考方向的角度为变量,以初始接触面积、接触点的个数和接触点分散均匀程度为目标函数,建立了冲压方向确定的优化模型。提出了运用熵值理论对各专家评估水平赋予权重值的改进层次分析法（AHP）得到目标函数综合权重。针对典型汽车覆盖件,应用KAMS软件在生成冲压方向的基础上仿真测试,测试结果方法的有效。     

汽车覆盖件冲压工艺CAPP系统特征建模技术

特征技术应用于汽车覆盖件冲压工艺CAPP系统被认为是提高汽车覆盖件制造水平,并逐步实现CIMS的关键.为此,本文对汽车覆盖件进行了特征分类,建立了面向CAPP系统的覆盖件特征表达模式.以UGII软件为开发平台,提出自动识别孔类特征算法,采用交互式特征识别方式识别其他特征,建立了覆盖件特征模型,解决基于特征的覆盖件冲压工艺CAPP系统信息输入问题.     

汽车覆盖件冲压变形趋向性控制

汽车覆盖件冲压成形过程中的变形是非常复杂的,在进行工艺设计和模具设计时不能用计算的方法得到变形的定量分布,为此,通过对覆盖件特点的分析,提出了对汽车覆盖件冲压成形进行变形趋势分析的方法,以及控制汽车覆盖件冲压变形趋势的措施,并进行了实例分析.     

铝合金汽车覆盖件前盖外板冲压工艺开发及优化

目的 针对汽车覆盖件前盖外板冷冲压成形过程中可能出现的拉裂、起皱和变形不均匀等问题,利用Autoform软件优化工艺参数。方法 以厚度0.95 mm的铝合金板料为原材料,基于CATIA三维建模软件构建覆盖件前盖外板的三维模型,利用AutoForm软件对覆盖件前盖外板的拉延成形过程进行数值模拟分析,通过单因素和正交实验优化拉延工艺参数,提高覆盖件产品成形质量。结果 单因素实验结果表明,当摩擦因数为0.1、冲压速度为200 mm/s时,随着压边力由1 200 kN增至2 200 kN,产品的最大减薄率由14.74%增到17.37%,安全区占比由81.5%增到84.66%;当压边力为1 600 kN、冲压速度为200 mm/s时,随着摩擦因数由0.1增至0.18,产品最大减薄率由15.79%增至19.47%,安全区占比先由83.64%增至84.69%,随后降低至84.13%;此外,冲压速度变化对产品的最大减薄率和安全区占比影响不明显。正交实验结果表明,当压边力为1 400 kN、摩擦因数为0.1、冲压速度为300 mm/s时,前盖外板产品冲压最大减薄率最优;在压边力为1 700 kN、摩擦因数为0.16以及冲压速度为400 mm/s条件下,前盖外板产品的冲压安全区占比和成形质量最优。结论 最优工艺参数如下:压边力为1 700 kN、摩擦因数为0.16、冲压速度为400 mm/s。     

浅谈汽车覆盖件冲压成形模具中锻造技术和铸造技术

汽车覆盖件冲压理论和技术的发展将带来汽车工业的发展和相关领域的发展。汽车覆盖件冲压理论和技术的发展将带来汽车工业的发展和相关领域的发展。     

基于KBE的冲压件自评价工艺方案设计

工艺方案的决策与评估是复杂冲压件工艺设计的关键部分,也是影响工艺设计智能化程度的重要技术问题。根据复杂冲压件工艺方案设计过程和专家经验,借助知识工程多智能决策技术,进行了复杂冲压件可行性工艺方案的设计,并运用价值工程和加权法将量化评价模型有机地融入智能决策系统中,实现了基于KBE的复杂冲压件自评价工艺方案设计。     

甘特图在汽车覆盖件冲压生产中的应用

简要介绍了汽车生产及汽车覆盖件冲压生产的组织形式与特点，从生产组织与劳动组织、生产控制及生产能力估算三个方面详细介绍了甘特图在汽车覆盖件冲压生产的应用。     

汽车覆盖件冲压成形灰色关联选材法研究

汽车覆盖件形状结构复杂,冲压时经常多发性地产生不同的成形缺陷,为了解决冲压选材问题,分析了以往选材研究的技术思想,通过试验检测冲压板料的性能数据,揭示当前冲压选材中仍然存在的问题,并使用灰色系统理论表征了冲压成形性能的灰色系统性质,提出应用灰色关联分析对覆盖件进行冲压选材的新方法,且针对行李箱盖内板实例性地说明使用这种方法进行冲压选材的决策过程.研究表明,采用本文方法可以解决传统冲压选材中离散性评判冲压板料各种性能指标的问题.     

汽车覆盖件成形工艺参数多方案管理系统

基于Siemens NX平台开发了汽车覆盖件冲压成形同步模拟系统Forming Analysis Wizard（FAW）,采用UDO关联技术与参数化关联技术,实现了工艺参数多方案管理功能。该系统可以在同一工序中定义多种方案,并对不同方案的工艺参数进行有效管理,为工艺优化提供参考依据。以某后排座靠背支架模型为实例,设置多...     

Feature-based geometric reasoning for process planning

We present a framework based on Domain Independent Form (DIF) features for automatic evaluation of manufacturability and process planning for machining. The framework enables interpretation of a common product model with respect to each task in the transition from design to manufacture. A key idea here is to generate the interpretation suitable for each task in two steps. In the first step, DIF features that are defined through feature enumeration are automatically extracted from the geometric model. The extracted DIF features are then mapped into features meaningful for individual tasks through geometric reasoning based on domain dependent knowledge. The formal approach to feature definitions and separation of the domain specific reasoning from the general geometric reasoning enable us to overcome the bottlenecks reported in features technology. Work reported in this paper has been funded in part by grants from Aeronautical Development Agency and the Department of Science and Technology.     

Production planning in automotive powertrain plants: a case study

Based on a real case study from the automotive industry, this paper deals with production planning in powertrain plants. We present an overview of the production planning process and propose a mixed integer linear programme to determine the production quantities of each product over a planning horizon of several days. Then, using real data of an engine assembly line, we simulate the performance obtained through the proposed model within a rolling horizon planning process. We perform multiple tests in order to evaluate the impact of two parameters involved in this process: planning frequency and frozen horizon length. Furthermore, in order to illustrate the value of improving coordination between engine plants and their customers, we evaluate the impact of the quality of demand information (orders and forecasts). We analyse the simulation results and provide insights and recommendations in order to achieve a good trade-off between service level, inventory, and planning stability.     

An AHP-multicriteria suitability evaluation of technological diversification in the automotive industry

This paper advances a methodological framework for analysing the process of technological diversification in the automotive industry and presents a multicriteria procedure, based on the analytic hierarchy process (AHP), to evaluate, in a simple and user-friendly manner, the suitability of technological diversification for any company in the automotive sector. The AHP-multicriteria procedure associated with the initial stage of the methodology and the decision support systems developed to evaluate suitability have been applied to 22 Spanish automotive companies. The multicriteria procedure classifies the companies into three different groups: (i) those that are suitable for diversification; (ii) those for which product development (innovation) or market development (internationalisation) is more appropriate; (iii) those that are not suitable for any diversification process. The true value added in this initial stage of the technological diversification process is not, despite its importance, the final classification of the firms, but the learning procedure derived from the multicriteria analysis and the evaluation of diversification suitability. From this learning procedure, a set of recommendations related to the diversification of the automotive companies is extracted.     

Reducing tardy jobs by integrating process planning and scheduling functions

This paper presents a dynamic approach to reduce tardy jobs through the integration of process planning and scheduling in a batch-manufacturing environment. The developed method aims at re-generating a schedule with fewer tardy jobs, step by step, by exploring the process plan solution space of the tardy jobs. The integrated system comprises a process planning module, a scheduling module, and an integrator module. The process planning module employs an optimisation approach in which the entire plan solution space is first generated and a search algorithm is then used to find the optimal plan, while the scheduling module is based on commonly used heuristics. Based on the job tardiness information of the generated schedule, the integrator module automatically issues a modification order to the process plan solution space of the tardy jobs. The process planning and scheduling modules are then re-run to generate a new plan/schedule solution. Through this iterative process, a satisfactory schedule can be gradually achieved. The uniqueness of this approach is characterised by the flexibility of the process planning strategy, which makes full use of the plan solution space intuitively to achieve a satisfactory schedule. Several examples are presented to confirm the efficacy and the effectiveness of the developed integration system.     

A green productivity based process planning system for a machining process

In the metal cutting industry, manufacturers have strived to increase energy efficiency and to reduce environmental burdens through the use of dust collectors and waste disposers. It is more beneficial and efficient to apply the front-of-pipe technology that prevents the sources of pollutants and minimises energy use through the redesign of products and the change of process planning and machining operations. In particular, process planning for the environment, called eco-process planning, is central to increasing energy efficiency and reducing environmental burdens because process planning decisions greatly influence machining performance. At present, greenability, a term used to indicate environmental friendliness, has been little considered as a major concern in the process planning stage because process planning decisions have focused on improving productivity aspects that include speed, cost and quality. Thus, it is essential to develop an eco-process planning approach that enables the harmonisation and enhancement of greenability performance while improving productivity performance, termed green productivity (GP). This paper presents the development of a GP-based process planning algorithm that enables the derivation of process parameters for improving GP in machining operations. The core mechanism of the algorithm is the realisation of the process improvement cycle that measures GP performance by the collection of machining data, quantifies this performance by categorical representation and predicts the performance through prediction models. To show the feasibility and applicability of the proposed algorithm, we have conducted an experiment and implemented a prototype system for a turning machining process.     

船舶焊接工艺知识管理技术研究

船舶焊接工艺设计涉及的工艺知识范围广泛,用到的信息和知识繁杂。因此,对船舶焊接工艺知识进行系统化表示,建立丰富的工艺知识库,不仅是船舶焊接工艺设计的基础,而且对船舶制造技术的提高具有重要意义。本文基于船舶焊接工艺知识管理系统（SWPKM）的开发,采用了面向对象建模和产生式规则技术,对船舶焊接工艺知识进行了全面分析,论述了船舶焊接工艺知识表示、工艺知识库构建等。     

More MILP models for integrated process planning and scheduling

The integration of process planning and scheduling is important for an efficient utilisation of manufacturing resources. In general, there are two types of models for this problem. Although some MILP models have been reported, most existing models belong to the first type and they cannot realise a true integration of process planning and scheduling. Especially, they are completely powerless to deal with the cases where jobs are expressed by network graphs because generating all the process plans from a network graph is difficult and inefficient. The network graph-specific models belong to the other type, and they have seldom been deliberated on. In this research, some novel MILP models for integrated process planning and scheduling in a job shop flexible manufacturing system are developed. By introducing some network graph-oriented constraints to accommodate different operation permutations, the proposed models are able to express and utilise flexibilities contained in network graphs, and hence have the power to solve network graph-based instances. The established models have been tested on typical test bed instances to verify their correctness. Computational results show that this research achieves the anticipant purpose: the proposed models are capable of solving network graph-based instances.     

Tolerance chart balancing for machining process planning

This paper provides a mathematical model for tolerance chart balancing for machining process planning. The formulation of the proposed model is based on the graphic ‘rooted tree’ representation technique in describing the sequence of the machining process. The criteria considered in the presented study are based on the combined effects of manufacturing cost and quality loss under constraints such as process capability limits, design functionality restrictions, and product quality requirements. Applications of these models include minimizing the total cost of manufacturing activities and quality related issues with process selection and tolerance allocation in machining process planning, particularly in the early stage of planning.     

STEP-based feature modeller for computer-aided process planning

Feature-based modelling has been considered as an indispensable tool for integrating CAD/CAPP systems. One of its advantages over conventional geometric modelling is the ability to associate not only geometric and topological information, but also form features, tolerances, material properties and other information which may be used during the process planning. This paper presents a STEP-based feature modeller (STEP-FM) for prismatic parts. High-level three-dimensional solid features are used as the basic entities for part design. The modeller relies on three main steps; (1) selection of the part base shape and overall size, (2) selection of the features to be added to or subtracted from the part being designed, and (3) providing information needed to define feature size, position, orientation and other attributes such as surface finish, tolerances, etc. The designed part is then exported as a STEP XML data format (according to ISO 2000 International Standards Organization ISO10303 — Part 224, Mechanical Product Definition for Process Planning Using Machining Features 2000 ISO Geneva ). This file can be used to integrate into CAPP/CAM systems without using a complex feature recognition process. An object-oriented approach is used in the definition and implementation of the product model. This approach offers advantages of incremental system development and reusability. An example is given to demonstrate the application of the developed modeller.     

A hybrid particle swarm based method for process planning optimisation

A process planning (PP) problem is defined as to determine a set of operation-methods (machine, tool, and set-up configuration) that can convert the given stock to the designed part. Essentially, the PP problem involves the simultaneous decision making of two tasks: operation-method selection and sequencing. This is a combinatorial optimisation problem and it is difficult to find the best solution in a reasonable amount of time. In this article, an optimisation approach based on particle swarm optimisation (PSO) is proposed to solve the PP problem. Due to the characteristic of discrete process planning solution space and the continuous nature of the original PSO, a novel solution representation scheme is introduced for the application of PSO in solving the PP problem. Moreover, two kinds of local search algorithms are incorporated and interweaved with PSO evolution to improve the best solution in each generation. The numerical experiments and analysis have demonstrated that the proposed algorithm is capable of gaining a good quality solution in an efficient way.