一种单元制生产方式设备布局问题的研究方法

单元制生产方式是适合于目前多品种、少批量市场需求环境下产生的先进生产制造方式,基于单元制生产方式的设备布局是实现精益生产的重要硬件支撑.对单元式生产方式下的设备布局进行了研究,把该种形式的设备布局分成两个阶段:第一阶段是制造单元的设计,第二阶段是对划定的制造单元进行布局,形成最终的设备布局.分别建立了相应的数学优化模型,通过实例验证了该方法的可行性和有效性.     

扇形子孔径布局H-S传感器对圆域的探测性能研究

通过Zernike模式波前重构算法进行计算机仿真计算,对扇形子孔径布局的Hartmann-Shack波前传感器探测性能进行仿真研究,对比分析了方形子孔径布局Hartmann-Shack波前传感器的探测性能.结果表明,扇形子孔径布局是一种有效的Hartmann-Shack波前传感器的布局方式,在低子孔径密度且径数目差异不多的条件下,比方形孔径布局探测精度更高.     

基于SA-QPSO算法的多层制造单元内部布局方法

针对多层制造单元内部的设备布局优化问题,本文建立考虑单元尺寸、物料搬运量、损失时间以及单元稳定性的多目标优化数学模型。为更快速、高效地求解该问题,使用模拟退火算法（Simulated Annealing,SA）确定单元内设备所在平面以及层面,使用量子粒子群算法（Quantum Particle Swarm Optimization,QPSO）确定设备具体坐标值和所在高度。以某汽车零件加工车间为实例,运用SA-QPSO算法生成直线形、“U”形和环形3种最优空间布局方案,验证了SA-QPSO算法在多层制造单元内部布局方法设计方面的可行性。     

浅析弯管机液压系统的工作原理及故障排除

随着工业自动化的发展，在工业生产中，换热设备使用极其广泛，而管式换热设备就是常见的一种。在这些管式换热设备中，采用U形弯管是非常普遍的。在实践中如何加工这些U形管有许多方法，如机械手或手动弯曲等。液压技术由于其潜在的许多优点，把他应用在弯管机上，简便易行，不失为一种良好的方法。     

某复杂蒙皮拉形中起皱缺陷的消除

目的对某复杂飞机蒙皮零件在拉形工艺过程中的起皱行为进行研究,以得到消除起皱缺陷的方法。方法分析了该蒙皮零件的型面特点,指出了拉形过程中出现起皱的原因。设计了3种改进的拉形方案,采用有限元仿真的方法对这3种方案进行模拟评估,确定了对起皱缺陷改善最为明显的一种,基于设备与工装的限制对该方案进行了调整,作为改善拉形质量的最终方案,并再次进行了有限元仿真验证。结果根据改进方案,在拉形工艺设计软件上生成拉形设备的数控代码,进行了生产性验证,与有限元仿真结果符合的很好,基本消除了起皱缺陷,提高了零件的成形质量。结论通过对拉形工艺中工装模具的优化设计,可以减少或避免起皱缺陷的出现。     

基于遗传算法的作业车间设备布局优化方法

针对作业车间设备布局这类多目标优化问题,在标准遗传算法的基础上,通过在染色体编码、约束处理、选择算子和变异算子设计、适应值计算等方面进行优化改进,提出了一种多目标作业车间设备布局优化算法,最后通过仿真实验验证了该方法的有效性.     

一种多行设备动态布置的方法

在简单分析比较4种基于启发式算法求解动态设备布局方法的基础上,提出了一种基于单亲遗传算法的相应遗传策略,发展了一种新颖的适用于动态设备布局的遗传换位操作算子,并提出在单期上应用换位概率的策略,大大增加了种群的多样性,明显提高了算法的性能.最后进行了仿真研究,并用提出的时间增长率和相对精度收敛率指标进行了综合分析.     

关于住宅布局设计中几个问题的思考

本文对住宅布局的实用性与功能的合理性进行了分析,现代居住条件下大进深单元式住宅空间不仅要有合理的平面布局而且要有合理的空间尺度,设计戍该以人为本,提高住户的生活品质.     

构树叶在风中的形态重构

通过风洞实验研究垂直于来流悬挂的构树叶在0~25m/s风速段的形态重构现象.根据构树叶分裂情况将其分成心形、单侧分裂、双侧分裂3种,迎风面正、反面各半.在实验风速段内,构树叶存在3类形态(飞翼形、锥形、薄三角翼形),主要有3种卷缩方式(U形、ω形和σ形).统计数据表明,树叶分裂情况会在发生概率上影响重构的形态和卷缩方式,但不会从根本上决定某一形态或卷缩方式的出现.与正面迎风比较,反面迎风的失稳重构次数减少,气动性能更佳.叶片角在风速小于6m/s时随风速增加锐减,然后变化速度减缓,最后风速大于14m/s后在0°附近几乎不变;随着雷诺数增加,构树叶的阻力系数减小,最后稳定于0.05附近.     

焊剂片约束电弧焊接三明治板熔滴过渡与熔池波动研究

针对焊剂片约束电弧(FBCA)焊接高强钢三明治板熔池研究难点,采用侧边贴敷耐高温石英玻璃片方法,采集焊接动态过程信息,实现熔池边缘曲线的提取与特征参数的计算,研究不同参数下熔滴过渡模式及熔池边缘曲线波动情况,分析熔池振荡角与焊接稳定性及焊缝成形之间的关系。结果表明：不同参数下FBCA焊接存在短路过渡、粗滴过渡、排斥过渡、细滴过渡、射滴过渡、弧桥并存过渡六种过渡方式,对芯板内熔池边缘波动的影响依次减弱;随着熔池振荡角变化,熔池边缘曲线形状存在混合U形、深U形及浅U形,电弧燃烧稳定性依次增强;当焊接处于弧桥并存过渡模式、熔池边缘曲线为浅U形时,电弧稳定燃烧,电弧力作用均匀,焊接过程稳定,焊缝质量最好。     

基于成组技术的多品种小批量产品工艺编码规则研究

在分析某类产品制造工艺及生产组织现状的基础上,基于成组技术开发了产品零部件的工艺编码规则体系,从而为该类产品制造工艺数据库的开发以及工艺数据的快速获取、共享和重用创造了条件．     

A comparison of focused cellular manufacturing to cellular manufacturing and job shop

The purpose of this study is to compare a focused cellular manufacturing environment with traditional cellular manufacturing, and job shop environments. We define focused cellular manufacturing as a configuration scheme that groups components by end-items and forms cells of machines to fabricate and assemble end-items. In addition, this research includes three levels of batch sizes and two levels of set-up times in its performance criteria which few researchers in this area have done. The results indicate that the focused cellular manufacturing scheme has a batching advantage. This advantage dominated the balanced machine utilization benefit of the job shop configuration scheme and out weighed the set-up time reduction advantage of the cellular manufacturing scheme for average end-item completion times and average work-in-process inventory levels. The cellular manufacturing and job shop schemes overcame the batch size advantage only when batch sizes were small or set-up times were large.     

A mixed integer linear programming formulation for optimal balancing of mixed-model U-lines

The mixed-model U-line balancing problem was first studied by Sparling and Miltenburg (Sparling, D. and Miltenburg, J., 1998. The mixed-model U-line balancing problem. International Journal of Production Research, 36(2), 485–501) but has not been mathematically formulated to date. This paper presents a mixed integer programming formulation for optimal balancing of mixed-model U-lines. The proposed approach minimises the number of workstations required on the line for a given model sequence. The proposed formulation is illustrated and tested on an example problem and compared with an existing approach. This paper also proposes a new heuristic solution procedure to handle large scale mixed-model U-line balancing problems. A comprehensive experimental analysis is also conducted to evaluate the performance of the proposed heuristic. The results show the validity and usefulness of the proposed integer formulation and effectiveness of the proposed heuristic procedure.     

JJF1070-2005的计量检验规则之问题研究

本文系统分析了JJF1070-2005《定量包装商品净含量计量检验规则》中定量包装商品净含量的计量检验规则,针对检验批实际平均含量的检验规则和单件定量包装商品净含量检验规则给出了两类检验规则的发生概率公式,并在此基础上对检验规则进行了详细的分析,指出了检验批实际平均含量的检验规则存在的问题,并结合实例分析了单件定量包装商品净含量检验规则所存在的不足及其可能的原因.最后,针对上述问题给出了改进建议.     

Managing production of high-tech products with high production quality variability

We consider production systems in technology industries where output quality of a single production run has a large variance. Firms operating such systems classify products into different quality bins and sell units in one bin at the same tagged quality level and the same price. Consumers have heterogeneous quality preferences and choose that quality that maximises their net utility. We examine firms’ assortment, production and pricing problem. We present a three-stage solution procedure that optimises the production quantity, quality specification and number of bins. In that regard, we show that for a manufacturing technology with known quality distribution and known distribution of customers’ quality preference, the optimal assortment and production quantity are set such that on average, the demand of each bin is exactly fulfilled. We examine the impact of an improved manufacturing technology, variation in consumer preferences and changing price premium on the optimal assortment, lot size, market share, yield loss and the overall profitability. We further show that when the quality distribution of the manufacturing process is unknown, downward substitution leads to product offering of higher quality and higher prices. Finally, we discuss practical considerations for pricing, technology and optimal product offerings, and explain the proliferation of bins witnessed in the last decade in the processor industry.     

A t‐chart for Monitoring Multi‐variety and Small Batch Production Run

Statistical process control is an important tool to monitor and control a process. It is used to ensure that the manufacturing process operates in the in‐control state. Multi‐variety and small batch production runs are common in manufacturing environments like flexible manufacturing systems and Just‐in‐Time systems, which are characterized by a wide variety of mixed products with small volume for each kind of production. It is difficult to apply traditional control charts efficiently and effectively in such environments. The method that control charts are plotted for each individual part is not proper, since the successive state of the manufacturing process cannot be reflected. In this paper, a proper t‐chart is proposed for implementation in multi‐variety and small batch production runs to monitor the process mean, and its statistical properties are evaluated. The run length distribution of the proposed t‐chart has been obtained by modelling the multi‐variety process. The ARL performance for various shifts, number of product types, and subgroup sizes has also been obtained. The results show that the t‐chart can be successfully implemented to monitor a multi‐variety production run. Finally, illustrative examples show that the proposed t‐chart is effective in multi‐variety and small batch manufacturing environment. Copyright © 2013 John Wiley & Sons, Ltd.     

‘Anticipatory batch insertion’ to mitigate perceived processing risk

Literature on lot-sizing models with random yields has been traditionally limited to random occurrences that cannot be anticipated in advance; for instance, day-to-day production errors and minor machine repairs. However, in reality, manufacturing processes are subject to other risks that are anticipatory, or non-random, in nature. One example would be yield loss resulting from non-random events such as process, product or material changes. Yield uncertainties of these types are temporary in nature with an impact that decays over time until the manufacturing system fully re-stabilises. One way of reducing the impact of such events is to split the lot and to process a small sub-batch in advance to stabilise the process, thus absorbing the risk associated with the change event. We refer to this approach as ‘anticipatory batch insertion’. This paper presents an exploratory study to analyse the performance of batch insertion under various scenarios related to product sensitivity, risk magnitude and schedule hardness. Results indicate that batch insertion is most advantageous whenever the production schedule is loose, multiple products are sensitive to the risk and the risk magnitude is high.     

Scope versus focus: issues of flexibility, capacity, and number of production facilities

How should a multi-product manufacturing firm design production facilities? How many facilities should it have? How many and which products should be assigned to each facility? What batch sizes/scheduling rules are appropriate for facilities making more than one product? These are questions that have become more relevant now as advances in manufacturing technologies offer an increasing array of equipment choices. In this article, we introduce models that can help operations managers answer the above questions. For a specific product mix, these models lead to explicit expressions for the number of facilities, the number of products assigned to each facility and their corresponding capacities. We evaluate the effect of different operating parameters and scheduling policies on the optimality of different configurations. In particular, we show that the choice of the scheduling and batch sizing policies can have a significant effect on the nature of the optimal mix of flexible and d edicated facilities as well the size of these facilities.     

Modelling infant failure rate of electromechanical products with multilayered quality variations from manufacturing process

The optimisation of product infant failure rate is the most important and difficult task for continuous improvement in manufacturing; how to model the infant failure rate promptly and accurately of the complex electromechanical product in manufacturing is always a dilemma for manufacturers. Traditional methods of reliability analysis for the produced product usually rely on limited test data or field failures, the valuable information of quality variations from the manufacturing process has not been fully utilised. In this paper, a multilayered model structured by ‘part-level, component-level, system-level’ is presented to model the reliability in the form of infant failure rate by quantifying holistic quality variations from manufacturing process for electromechanical products. The mechanism through which the multilayered quality variations affect the infant failure rate is modelled analytically with a positive correlation structure. Furthermore, an integrated failure rate index is derived to model the reliability of electromechanical product in manufacturing by synthetically incorporating overall quality variations with Weibull distribution. A case study on a control board suffering from infant failures in batch production is performed. Results show that the proposed approach could be effective in assessing the infant failure rate and in diagnosing the effectiveness of quality control in manufacturing.     

Tabu search-based algorithm for the TOC product mix decision

The theory of constraints (TOC) is a management philosophy that maximizes profits in a manufacturing plant with a demonstrated bottleneck. The product mix decision is one application of TOC that involves determination of the quantity and the identification of each product to produce. However, the original TOC heuristic is considered to produce unrealizable solution when a manufacturing plant has multiple resource constraints. This paper presents a tabu search-based TOC product mix heuristic to identify optimal or near optimal product mix for small problem instances under conditions where the original TOC heuristic failed. The tabu search-based TOC product mix heuristic is further used to solve large problem instances typical of practical manufacturing scenario. The experimental results for small to medium size problem show that the tabu search-based TOC heuristic compares favourably with those of optimal methods. Large size problems for which optimal methods have not been established in terms of feasibility in computation times were also solved in reasonable times with good quality solutions, thus confirming that the proposed approach is appropriate for adoption by production planners for the product mix problem in the manufacturing industry.