带有工艺约束的并行多机调度策略

针对光刻设备组的生产特点,基于最小化加工时间对其调度问题建立了整数规划数学模型,并提出了一种启发式调度策略.运用Extend仿真软件对传统的FCFS和启发式调度策略分别进行仿真,结果表明,启发式调度策略在减少加工时间和提高设备利用率上皆优于FCFS.     

集成启发式规则的混合整数规划调度模型

针对生产调度优化问题,提出了一种集成启发式规则的混合整数规划调度模型。在分析启发式规则逻辑关系的基础上,用布尔逻辑变量表达启发式规则建立了启发式规则的基本逻辑表达式及其等价代数表达式,基于基本表达式给出了启发式规则的数学表达。将启发式规则的代数表达式与混合整数规划相结合,实现了启发式规则的集成。集成启发式规则的混合整数规划调度模型在结合启发式规则的基础上进行数学优化,克服了混合整数规划难以直接利用经验规则和基于规则的调度优化性难以保证的不足。最后以某炼油过程生产调度为例说明了模型的有效性。     

自动化立体仓库出入库调度优化

针对自动化立体仓库的出入库调度优化问题,提出一种基于遗传算法/层次分析法(GA/AHP)的调度规则优化方法.遗传算法中的每个染色体都代表一组可用于描述具体调度方案的规则组合,并对染色体采用分段整数编码;为获得适应度函数值,利用一种集成层次分析法的决策优化方法求取相应的适应度值.优化调度仿真结果表明,该方法能有效地应用在自动化立体仓库的出入库调度规则的优化问题上.     

一种并行遗传算法在家纺企业车间调度的应用

针对家纺企业受特殊工艺约束的车间调度问题,提出了一个基于向量组编码的新的遗传算法,并设计了EOX交叉和启发式变异方法.在基于遗传算法自然并行性特点的基础上,实现了主从式控制网络模式下并行遗传算法.通过仿真实验证明,建立的算法是有效的,收敛速度快,具有较高的并行性,优于普通的遗传算法.     

面向订单的生产计划与调度的综合优化

研究了一个多订单环境下的生产计划与调度集成优化问题,以实现准时生产为目标,综合考虑产品装配结构约束的订单任务计划与订单产品零部件的加工调度,采用直接面向客户订单的工序调度模式建立了计划和调度的综合优化整数规划模型.设计了带精英策略的蚁群算法作为该数学模型的求解方法,并通过对比试验为该算法选取最佳的搜索参数.实例仿真结果表明,所建模型的正确性以及蚁群算法求解该问题的可行性和有效性.     

装配作业车间分批调度问题的算法对比

建立最小化makespan的装配作业车间分批调度模型,利用遗传算法构建基于整体集成优化策略、分层迭代优化策略和双层进化策略的求解算法。它们的区别在于处理批量划分问题和子批调度问题的联合优化机制不同。最后通过仿真实验对比了几类算法的求解效果和收敛速度,并分析了它们的适应性特点。     

钢铁企业副产煤气优化调度问题模型及算法

考虑钢铁企业副产煤气优化调度问题,在分析问题特征的基础上,建立了数学规划模型。针对模型特点,将遗传算法与混沌理论相结合进行模型求解,在初始种群中引入基于启发式规则生成的优良个体来提高收敛速度;通过建立个体精英库防止最优值的丢失;引入基于混沌序列的邻域搜索以提高算法的寻优效率。通过仿真实验验证了模型与算法的可行性和有效性。     

基于仿真的半导体自动物料搬运系统调度优化

利用Arena仿真软件对半导体制造中的Intrabay系统进行了仿真建模,根据关键因子和等待比例两个变量将系统状态分为三种情况,利用遗传算法与仿真模型结合来确定两个变量的阈值和三种系统状态下各自采用的调度规则,实现系统的动态调度。仿真实验表明,所确定的调度规则比使用静态调度最长等待时间规则获得了更好的性能指标。     

多资源作业车间的混合自适应GA优化调度

针对多资源约束的车间调度问题,将启发式算法和自适应GA优化方法结合起来,提出了混合自适应GA方法,建立了多资源约束的车间优化调度模型.根据启发式调度算法中优先规则对调度目标的影响,设计了新的编码规则.采用正弦函数作为自适应因子,使得交叉概率和变异概率随群体的适应度自动改变,提高了运算的效率,克服了启发式算法和普通GA的缺陷.通过实例仿真并与其他算法比较结果表明,混合自适应GA算法可以很好的解决作业车间在机床、刀具等多种生产资源约束下的优化调度,并在评价指标上较其他算法更优.     

基于仿真优化的驳运空箱调运系统研究

运用仿真优化方法对驳运空箱调运系统进行了研究.根据系统作业中存在的不确定性、随机性活动的特点,建立了空箱调运系统的离散事件仿真模型;针对空箱调度规则,建立了数学模型;并运用仿真模型与启发式算法相融合的仿真优化方法进行求解.规划目标是在满足系统作业要求的前提下,以最大化计划渡柜数为目标,优化渡柜规则.即,根据各个码头对空...     

基于VERICUT包装容器模具数控加工仿真及优化技术

在包装容器生产中,关键的是容器模具的加工,而VERICUT是一款既能完成加工仿真又能进行较好优化的三维软件,可实现加工轨迹仿真和机床仿真,图形逼真,而且可通过已有经验数据库来调整各个工序的进给率等参数,提高加工效率,实现NC代码的优化.结合某塑料容器模具的实例展现了VERICUT环境下数控加工仿真及优化的过程,为包装容器模具的生产提供有意的指导.     

Computer-aided optimization of multi-pass turning operations for continuous forms on CNC lathes

The Computer Numerical Control (CNC) machine is one of the most effective production facilities used in manufacturing industry. Determining the optimal machining parameters is essential in the machining process planning since the machining parameters significantly affect production cost and quality of machined parts. Previous studies involving machining optimization of turning operations concentrated primarily on developing machining models for bar components. Machined parts on the CNC lathes, however, typically have continuous forms. In this study, we formulate an optimization model for turned parts with continuous forms. Also, a stochastic optimization method based on the simulated annealing algorithm and the pattern search is applied to solve this machining optimization problem. Finally, the applications of the developed machining model and the proposed optimization algorithm are established through the numerical examples.     

UG集成环境下数控机床虚拟样机的实现

数控机床是一种重要的技术装备。为提高数控机床的设计水平和能力,在数控机床的设计开发过程中需要引入新的技术和设计手段。为把虚拟样机技术应用到数控机床设计开发的工程实践中,基于虚拟样机的概念讨论了数控机床虚拟样机的具体实现过程,分析比较了实现该过程的分布式软件平台和UG集成软件平台的特点。以数控铣床新产品开发为例,研究了UG集成环境下数控机床虚拟样机的构建与仿真过程,包括数字模型与装配、运动仿真、结构分析以及在虚拟样机上的加工仿真,给出了相应的示例。研究表明,应用UG的各功能模块可以有效地构建数控机床的虚拟样机并对其进行全面的仿真,使所设计的数控机床得到全面优化,为数控机床的开发设计提供了一种可行的先进方法。     

叶轮零件集成数控编程与数控加工过程仿真

探讨应用于叶轮类零件的集成数控编程与加工过程仿真技术,给出了其功能结构图与流程图,利用商品化软件SURFCAM和VERICUT构建了集成数控编程与加工过程仿真环境,并利用其实现了一个整体叶轮零件的数控编程与加工过程仿真,实际加工结果表明其能够有效解决叶轮类零件的复杂曲面加工问题.     

基于DEA的制造系统全要素能源效率评价与优化

针对目前机械加工车间制造系统能源效率评价需要基于大量的机械加工试验来分析能量消耗,需要基于经验公式来获得能源效率指标,以及没有实现基于能效评价后的能效优化等问题,基于生产管理信息系统监测数据,提出一种制造系统全要素能源效率评价指标。用数据包络分析方法对机械加工车间制造系统全要素能源效率进行评价,使用能源效率优化分析方法构建能源效率函数关系,从而提出降低能耗和提高能源利用率的定量科学方法。最后以某变速箱装配车间为例,通过实例分析,验证该评价及优化方法的理论及应用价值。     

A radius compensation method of barrel tool based on macro variables in five-axis flank machining of sculptured surfaces

Barrel tool radius compensation is very important to improve the five-axis CNC machining precision and efficiency of sculptured surfaces. By combining macro variables and math function of CNC controller, a radius compensation method of barrel tool based on macro variables in five-axis flank machining of sculptured surfaces was presented. The basic principle of barrel tool radius compensation in five-axis flank machining was firstly investigated. For a specific five-axis CNC machine tool with dual rotary tables, a relationship equation between compensated cutter location (CL) data and machine control (MC) data could be derived. A post-processor with the function of five-axis barrel tool radius compensation was then developed by using the C++ language, which could generate the NC programme with macro variables of barrel tool radius compensation. Finally, the NC programme was obtained automatically by the developed post-processor for the aero-engine blade surface machining. The machining process was simulated on the software VERICUT, and machining experiments were also conducted on the five-axis machine tool. Both the simulation and experimental results showed that the proposed method could perform the function of barrel tool radius compensation in the NC programme for five-axis flank machining.     

An Internet-enabled image- and model-based virtual machining system

Virtual reality (VR) can be described as a four-dimensional (4-D) simulation of the real world, including the 3-D geometry space, 1-D time and the immersive or semi-immersive interaction interface. VR applications in mechanical-related research areas are becoming popular, e.g. virtual layout design, virtual prototyping, Internet-based virtual manufacturing, etc. However, research in VR applications is facing conflicting requirements for high rendering quality and near real-time interactivity. This paper represents an Internet-based virtual machining system that builds an integrated VR scene, which combines images and models, to overcome the above conflicts. This research is divided into three parts: first, image mosaics techniques are used to implement an Internet-based virtual workshop, which is an image-based virtual scene. The method of obtaining original sequential images, the principle of image mosaics to realize automatic seamless stitching, and projection transformation matrices to reconstruct a closed inward-facing space are presented. Secondly, a model-based virtual milling machine has been constructed with three detailed approaches: a category-based dynamic graph structure to support collision detection, a relation-oriented collision detection method to improve the efficiency of collision detection, and a dynamic modelling method to model a dynamic workpiece object. Finally, an Internet-based virtual milling system, which is the integration of the image-based virtual workshop and the model-based virtual CNC machine, is constructed using the reposition method to achieve visual consistency of the virtual objects and images. This system, which includes an integrated scene, combines the advantages of image-based VR and model-based VR. Consequently, this system has both high rendering quality and good real-time interactivity.     

Heuristic optimization system for the determination of index positions on CNC magazines with the consideration of cutting tool duplications

This paper presents a meta-heuristic optimization system developed for the determination of optimal index positions of cutting tools on the tool magazines (automatic tool changer (ATC) or turret magazine, etc.) of CNC (computerized numerical control) machine tools. The selection of index positions is performed using a simulated annealing (SA) algorithm that takes the following as the input: (1) a list of cutting tools assigned to certain machining operations; (2) the number of copies of each cutting tool available in the workshop; (3) total number of index positions on the tool magazines; (4) the indexing time of a tool magazine of a CNC machine tool specified by manufacturer. Then, the SA algorithm determines index locations of cutting tools on the tool magazines. Dereli et al. and Dereli and Filiz previously studied the present problem by using genetic algorithms (GAs). However, the duplication of cutting tools was not taken into account in their works, although it can reduce the total tool-indexing time and therefore improve the productivity considerably. Nevertheless, the consideration of the ‘tool duplications’ makes the problem much harder to model and to solve. In this paper, a novel solution representation-scheme based on the SA, which enables easy manipulation during feasible neighbourhood solution generation, is proposed for the determination of the index positions of cutting tools on the CNC magazines with the consideration of ‘tool duplications’. Example problems are solved to present the implementation and merits of the proposed optimisation system. It is shown that it is possible to allocate the cutting tools in an efficient manner on the CNC magazines with the developed system.     

Application of tabu search to process plan optimization for four-axis CNC turning centres

This paper describes our adaptation of the tabu search methodology to solve the process plan optimization problem for four-axis CNC turning centres. Optimization of a process plan (specifically, the allocation of operations to spindles and turrets) to minimize the cycle time for machining a workpiece is not a trivial problem. This is due to the highly combinatorial nature of the problem that arises from the presence of dual spindles and dual turrets and the machine's ability to perform operations in parallel machining and simultaneous machining modes. Our experiments to date have shown that the tabu search based approach can be very effective in process plan optimization, and is well suited for incorporation in CAD/CAM systems for four-axis CNC turning centres.     

基于 UG10.0 整体叶轮数控成形仿真研究

由于整体叶轮构造复杂,加工精度要求严格,其叶片的型面为自由型面并有一定的扭曲,同时叶片内流道较窄,为此在加工时很容易出现过切、碰撞、干涉等现象,加工难度大。结合工程应用,设计了整体叶轮的数控成形整套加工方案,并基于UG 10.0软件的CAD/CAM功能模块,重点研究了叶片成形过程仿真,验证了方法的可行性。所提出的数控成形加工方案,经仿真验证叶轮能够获得很好的成形,对整体叶轮及类似零件的精密成形加工具有一定的工程实际意义。