基于捷径重试规则晶圆带式搬运系统性能优化

Performance optimization of the wafer conveyor handling system using the crossover retrial rule

开口管桩由于其承载力高、质量可靠、施工方便等优点得到越来越广泛的应用.土塞的生成使得开口管桩沉桩阻力不同于闭口管桩,不仅包括桩外侧摩阻力、桩端阻力,桩内侧摩阻力亦是其重要组成部分.针对开口管桩沉桩受力特性,采用自主研发的大尺度模型试验装置,进行不同桩靴形式下开口管桩的贯入试验,并与闭口管桩进行对比分析.研究表明,开口管桩随沉桩深度的增加趋于闭塞,沉桩阻力随沉桩过程基本呈线性增加,桩内、外侧单位摩阻力均存在"侧阻退化"效应;桩体贯入时桩周地表隆起量随径向距离增加逐渐减小,隆起速率随沉桩深度增加逐渐变缓,桩周土影响范围约为5 ~ 7倍桩径;桩靴对开口管桩土塞生成、沉桩阻力和挤土效应均有重要影响,内30°桩靴土塞生成高度、桩内侧摩阻力及其所占总沉桩阻力比例最大,桩周土地表隆起量最小,外30°桩靴与内30°桩靴情况相反,直角桩靴居中;闭口管桩沉桩阻力、外侧摩阻力与挤土程度均大于开口管桩.

The semiconductor wafer fabrication system is one of the most complex discrete manufacturing systems owing to its great number of production steps,heavy re-entry production flow,various kinds of products,etc. The automatic material handling system plays a key role in improving the production efficiency,reducing the work in process( WIP),and shortening the production cycle time of the semiconductor factory. To rapidly and effectively evaluate the impact of crossover systems on the overall performance of transport systems in wafer production,a performance analysis model was built by mathematical analysis and a decision-making method of crossovers was established. In the modeling procedure,the retrial transportation rule was first introduced. Then,considering the change in retrial rate affected by the crossovers strategy and referencing the related retrial queuing model,the mathematical expression of the expected WIP was constructed. Simultaneously,according to the cost of each crossover,the mathematical expression of the cost of crossovers was built. The optimization analysis model was obtained with the objective of minimizing the number of crossovers and WIP. Furthermore,the constraint conditions based on the length of the conveyor belt were introduced,so that the number of WIP products on each conveyor belt and crossover would not exceed the capacity limit of the conveyor belt. Finally,the NSGA-II algorithm was used to solve the multi-objective optimization problem. The relation between the number of WIP and cost of crossovers under different logistics loads was investigated,and Pareto frontier charts were drawn up for comparative analysis. The influence of parameter settings on the objective function of the system was studied,and the solution set was classified by clustering the analysis algorithm. Based on the aboveanalysis results,the best strategy of system crossovers was summarized. By comparing the proposed system with the existing system and transportation strategy,the effectiveness of the strategy in reducing cost and WIP was confirmed.