基于STEP-NC的工艺规划优化方法研究

在重点分析零件特征典型加工方案及加工方案组合优化原则的基础上,基于STEP-NC应用遗传算法建立了零件加工方案组合优化的数学模型。并将该方法应用到具体零件的工艺排序决策过程中,通过编码、杂交、复制、变异等得到满足零件要求的最优或接近最优的工艺路线。验证了遗传算法在STEP-NC工艺路线排序中的有效性。     

箱体零件数控加工路线研究

针对箱体类零件的特点,探讨了箱体零件加工工艺路线的确定原则和程序;阐述了箱体类零件的特征型面描述方法;建立了不同特征的加工方法匹配规则库,实现了零件特征要素加工方法的决策;同时研究了零件一次装夹的优化问题,建立了数学模型.实现箱体零件特征要素加工方法的决策和工步排序,最终得到了箱体零件在加工中心上的最优工艺路线.对传统工艺过程进行优化具有非常重要的工程实用价值.     

一种零件切削加工工艺路线仿真方法

工艺路线快速仿真对于制造业而言有其重要意义.提出了工艺路线仿真算法,以零件形状特征描述为桥梁,建立工艺路线到加工特征的映射,然后将加工特征反映到零件三维模型上,从而实现零件三维模型的工艺演变.实例证明,该方法是一种简单有效的工艺路线仿真方法.     

基于A3C的特征重构工艺路线规划方法

针对柔性加工系统中零件发生特征重构的工艺路线规划问题,结合异步优势演员-评论家(A3C)算法的并行、异步、响应速度快以及决策经验可复用性、可扩展性的特点,提出了基于A3C算法的特征重构工艺路线规划方法。在零件发生特征重构的背景下,基于马尔可夫决策过程定义了状态、动作空间和奖励函数。针对A3C智能体在选取机床、刀具和进刀方向时可能会陷入局部最优,提出了随机贪婪策略,以扩大解的空间、提高解的质量,且为了避免A3C智能体在零件发生特征重构时陷入大量的试错中,提出了快失败策略,以加快智能体规避特征约束的能力,提高响应速度。仿真实验证明,所提方法能有效解决零件发生特征重构的工艺路线规划问题,且相比基于遗传、蚁群和模拟退火算法的工艺路线规划方法,所提方法在零件发生特征重构时响应速度更快,解的质量更高。     

基于特征的齿轮轴类零件工艺决策系统的研究

文章探讨了基于特征的零件精度信息的描述。依据决策树的原理生成特征加工方法。由反向设计法生成特征加工链。通过给定的齿轮轴类件工艺过程决策原则确定零件加工路线。     

CAPP系统中面向对象的模板式工艺决策方法研究

根据基于面向对象技术及典型零件加工工艺路线模式化特点，提出了一种新的CAPP系统工艺路线决策方法－面向对象的模板工艺决策方法，通过总结大量典型零件加工工艺，建立了多层次的工艺模板库及工艺规则库，同时，采用层次递阶式推进策略，由零件的基本特征确定加工工艺的基本模块序列（基序），由基本特征参数及辅助特征等因素确定模块内各特征表面的加工顺序及详细内容（子序），最后通过模块集成生成完整的加工工艺路线，这种工艺决策方法使整个CAPP系统既吸收了派生法的类比设计思想，又具有创成功能，因此所开发的CAPP系统具有更高的效率和更强实用性。     

遗传算法在机械零件加工工艺决策中的应用和实现

通过对箱体类零件典型加工路线的分析，结合遗传算法的特点，建立了机械零件加工工艺决策的数学模型，提出了基于遗传算法的工步排序优化方法。并以箱体类零件为例，阐述遗传算法在零件加工工艺决策过程中的应用和实现。     

基于遗传算法的零件多加工方案组合优化方法

对非线性工艺规划中零件加工方案决策问题进行探讨,提出了先将加工特征的多个加工方案合理组合成零件的多个加工方案,再对零件的各加工方案进行排序的分步决策思想。在分析零件特征典型加工方案及加工方案组合优化原则的基础上,建立了零件加工方案组合优化的数学模型,设计了相应的遗传操作算法,并用典型算例说明了算法的应用,计算结果与专家决策结果基本吻合。所建立的模型不涉及具体的加工特征和加工方法,具有通用性。     

基于实例推理和专家系统的综合工艺决策方法

将基于实例的推理和专家系统创成法相结合，构造了一个实用的综合工艺路线决策方法。实例的推理是根据结构和工艺的相似性，按特征矩阵和进级匹配提取最相似实例，对相似实例的工艺进行变异设计，即可完成新零件的工艺过程设计；专家系统创成法是由专家系统的推理机依据知识库和信息库进行推理决策，自动创成得到零件的机械加工工艺过程。该方法非常适用于多品种、小批量生产类型的机械制造厂进行零件的机械加工工艺过程设计。     

回转类零件基于 CAD/CAM 集成的工艺设计

主要讨论了回转类零件基于ＣＡＤ／ＣＡＭ集成的工艺设计方法，采用子工艺路线的设计方法，通过不同的子工艺路线的合理组合而构成了整个零件的加工工艺路线。在系统自动产生加工工艺路线的基础上，对计算机产生的结果加以修改和决策，可以得到符合实际加工情况的加工工艺。     

基于特征工艺重用的箱体零件工艺规划研究

针对箱体类零件结构的复杂性 ,提出了基于特征工艺重用的工艺变型设计方法 ,由基于实例的方案重用技术生成零件特征的加工链 ,将基因遗传 /禁忌混合算法应用于加工工序的排序 ,从而获得了零件合理、优化的工艺方案     

几何增强的装配工艺本体建模

包含产品几何与非几何信息的产品装配要求是装配工艺设计的主要依据,对装配工艺设计决策结果具有决定性的影响。在装配工艺模型中描述产品的几何相关信息能够更好地表达如装配顺序,装配路径等内容,同时可以更好地辅助装配工艺决策,提高决策的自动化水平。提出一种几何增强的装配工艺本体模型,利用语义本体技术,建立产品几何信息在装配工艺中的描述方法,数据结构与关系描述。并以该模型为基础,建立基于几何增强装配工艺本体的装配工艺决策框架。该框架分为两部分：一是采用几何增强的装配工艺本体模型描述产品几何信息和装配工艺信息的数据结构和相互关系;二是为了让几何信息与装配工艺信息之间存在的丰富的隐含关系显性化,对语义本体推理机制进行增强,提出推理单元的概念,使决策框架具有从产品几何信息中推理装配工艺相关信息的能力,有效地支持装配工艺决策。以针对某传动器产品装配顺序决策的过程,验证所提出的几何增强装配工艺本体模型与框架的有效性。     

基于质量特征产品装配顺序规划的逆向推理算法探究

在Petri网柔性装配系统装配顺序规划中引入装配质量要素,并以装配零件的装配自由度,装配作业后稳定性,装配零件配合精度对装配质量的影响作为基本因子,提出装配质量置信度概念,解决柔性装配系统装配规划中装配质量及其定量化问题。根据装配形成的产品在Petri网装配状态图中表示为一个最终库所的特点,应用改进B树模型,提出仅以变迁信息的产品装配顺序规划Petri网逆向推理算法,简化装配顺序规划推理过程,对于多个变迁均可生成最终成品的情况,亦给出装配顺序规划的解决方案,并以摩托车发动机的装配为例,证明该算法是可行的。     

Research on the selectable disassembly strategy of mechanical parts based on the generalized CAD model

Disassembly has gained much attention due to the growing concerns of material resources, energy conservation, and environmental conscious. The process of disassembly attempts to breakup a product into several pieces, with the expectation that the pieces together have a net value greater than the discarded product. In analyzing these aspects, one needs to determine all feasible ways to disassemble a product. This is especially true for the complex products like automobile, aircraft, etc. Most researchers took the algorithm of complete-disassembly planning to design for disassembly, although the feasible disassembly sequence can be obtained, parts of a assembled entity should be removed totally. And the required S (refers to disassembly sequence) could be gained through the proper analysis and evaluation; however, there are so many difficulties in this process and it is hard to obtain the optimum solution, especially when there are many parts in assembled body (such as automotive product). Therefore, it is very necessary to research the selectable disassembly algorithm of mechanical parts. This paper puts forward an algorithm on the selectable disassembly strategy of mechanical parts based on disassembly wave concept. It is comparatively easy and efficient to search, and get the optimal selectable disassembly sequence of mechanical parts with less amount of computing. It is so significant for all the steps of maintaining, recycling and discarding. This project is sponsored by National Natural Science Fund Project (5975042) and Shanghai Natural Science Fund Project (02ZF14024).     

Integrated assembly and machining planning for electronic products using a genetic algorithm approach

To produce an electronic product, both assembly operations and machining operations are required in the process plan. In most cases, the assembly operations and machining operations need to be combined in a continued order with an integrated sequence. This is different from the traditional process planning approaches in which machining operations and assembly operations are separated as two independent tasks with no interactions. For an electronic product, the two types of operations and the associated costs may affect each other in an interactive way. Therefore, the sequence planning of assembly operations and machining operations must be analyzed with an integrated model. In this research, a graph-based model is presented to represent the assembly and machining operations in an integrated model. The related operation cost functions are developed to evaluate the costs for the integrated assembly and machining sequences. The integrated sequence planning problem is solved using a genetic algorithm approach with an objective of lowest operation costs. As a result, the assembly operations and machining operations can be planned in an integrated sequence suitable for producing electronic products. The result shows that the developed method using the genetic algorithm approach is efficient for solving the integrated sequence planning problem. Example products are demonstrated and discussed.     

面向大型产品装配序列规划的分类方法研究

讨论了在对大型产品进行装配序列规划时 ,为了简化装配序列产生过程 ,需要对待装配大型产品按操作复杂度分成两类 ,即复杂装配部分和简单装配部分 ,复杂部分进行虚拟装配规划 ,简单部分进行自动装配规划。分类时 ,首先对装配产品进行子装配体识别以得到组件 ,然后利用分类算法将组件分为两类。     

Efficient method of assembly sequence planning based on GAAA and optimizing by assembly path feedback for complex product

In the process of complex product assembly, assembly resources (fixtures, tools, operations, and so on) must enter assembly environment with parts together to rapidly finish product assembly. Assembly planning must take assembly resources into account fully. But, designer cannot plan every assembly procedure because of the lack of assembly resources during assembly design. Then, it will cause assembly failures and redesign for assembly easily. This paper investigates an efficient method of assembly sequence planning based on genetic algorithm and ants algorithm (GAAA) and optimizing by assembly path feedback to assembly process planning including assembly resources for complex products. Firstly, a new GAAA is investigated to rapidly plan assembly sequence in order to solve the nondeterministic polynomial-bounded problem in high searching and solving efficiency. Secondly, on the basis of the assembly sequence, a B-Rep filling algorithm which can form a swept volume between the part and its kinetic orientation is developed to plan assembly path interactively. Thirdly, the performance of the assembly path according to the assembly sequence is analyzed and sent back to avoid the most of assembly collisions and interventions during product assembly design. Lastly, we develop a simulating system to simulate assembly sequence and path based on component application architecture for CATIA V5. The simulating result proved that the proposed method of assembly sequence planning based on GAAA and optimizing by assembly path feedback for complex products is efficient. Assembly optimal design including assembly resources can work well.     

An intelligent interactive approach for assembly process planning based on hierarchical classification of parts

Assembly process planning is a difficult problem in the product design and development process. In order to reduce the difficulty of assembly process planning (APP), this paper presents an approach to finding a practical plan for assembly process through the intelligent interactive method based on hierarchical classification of parts. First, two hierarchical classification principles towards interactive disassembly are presented based on the key assembly constraint (KAC). Then, the initial assembly relationship of the product is readjusted to a new hierarchical structure which is more suitable for assembly planning according to a novel hierarchical classification algorithm. On the basis of the new hierarchy of product, an intelligent disassembly-based approach is presented, which not only takes full advantage of the ant colony algorithm for searching and constructing an initial assembly sequence with three available assembly principles, but also makes full use of the experience and knowledge of the human being for achieving a better assembly process. The intelligent disassembly approach can achieve an optimized assembly sequence, paths and scheme necessary information regarding the required assembly fixtures and tools. Finally, a case study shows that the proposed approach is feasible and practical.     

粒子群算法在装配顺序规划中的应用

装配顺序规划是计算机辅助工艺设计的一个重要环节,影响着轿车车身的装配质量和效率.针对当前装配顺序规划易产生组合爆炸等问题,提出了基于粒子群算法的装配顺序规划算法.装配偏差是影响装配质量的重要因素,因此应用装配体的装配偏差评价装配顺序.在装配顺序规划过程中,首先将装配顺序编码为粒子,根据所建立的判断规则进行识别粒子的可行性,并通过装配偏差评估可行粒子的适应度值,然后根据粒子群算法过程规划装配顺序,最后采用前翼子板案例阐述装配顺序的生成和优化过程.     

基于遗传算法的箱体零件加工路线决策方法研究

在对箱体零件典型加工路线分析的基础上，定义了工步优先权和加工路线能量函数，建立了工步排序的数学模型，提出了基于遗传算法的工步排序优化方法，并对遗传操作的算法进了改进设计，最后，用典型算例说明算法的应用。排序以典型加工路线为目标、零件的特殊要求为约束，将排序算法与零件型面、加工方法相分离，提高了算法的适用性、通用性和灵活性。