监控不合格品率的MEWMA-p控制图设计

传统Shewhart-p控制图只对单一属性的不合格品率进行监控,在过程发生偏移时有一定的滞后性。为提高不合格品率控制图的精度,提出一种多元指数加权移动平均不合格品率(multivariate exponentially weighted moving average p, MEWMA-p)控制图。该控制图将多个属性的不合格品率应用于多元指数加权移动平均控制图,可同时对多个属性进行监控,并且对于小范围的偏移更加敏感。对比分析同等偏移程度下指数加权移动平均不合格品率(exponentially weighted moving average p, EWMA-p)控制图与MEWMA-p控制图的平均运行长度(average run length,ARL)结果,并通过模拟仿真说明该方法的有效性。     

廿一世纪的超严格质量要求

一、超严格质量要求的概念 近一二十年来,科学技术的发展日益迅猛。例如,电子产品的不合格品率已由过去的百分之一、千分之一降低到百万分之一乃至十亿分之一的水平。过去在统计控制状态(State in statisticalcontrol)下的不合格品率约为2.7×10~(-3),现在则为2×10~(-9),即要比过去降低135万倍！如此严格的质量要求可称之为超严质     

企业为实施6σ管理应具备的条件

一、有必要实施6σ管理的企业 "6σ"是表示产品质量和过程质量的一个质量统计术语,指100万件产品中的不合格品不超过3.4件,或100万次生产作业、服务活动中的失误不超过3.4次.     

视觉检测系统在烟草包装机中的应用

目的在烟草包装过程中不可避免地有不合格品产生,研究利用视觉检测系统及时发现不合格品,以有效提高烟草包装质量。方法给出烟草包装机的视觉检测系统设计方案,分析视觉检测系统的检测过程及原理,并进行实机测试。结果添加视觉检测系统后,不合格烟包的有效剔除率比原来提高2.5%左右。结论通过在烟草包装机上添加视觉检测系统,利用图像相似性检测及边缘检测原理,可以有效提高不合格烟包的剔除率,降低了包装材料的消耗,减轻了下游机的运转负担。     

ISO9002中不合格品控制要素的实施要点

企业建立并实施质量体系 ,确保影响质量的各个因素处于受控状态 ,使产品的质量满足顾客的需求。在生产的过程中 ,不可避免地会产生不合格品 ,而最为重要的是企业应对不合格品进行有效的控制 ,以达到防止顾客收到不合格品并避免进一步加工不合格品而发生不必要费用的目标。由于不合格品的产生是由多种因素造成的 ,产生不合格品的多少是衡量一个组织生产管理水平的综合指标 ,为此该要素在质量体系现场审核中受到特别的关注。1　不合格品的控制程序要点及内容参照ＩＳＯ90 0 4 - 1:1994标准 ,明确不合格品的控制程序要点及内容包括以下几个方面…     

现场工业工程(Ⅷ)

16　防止失误装置为了在工序中作出好的质量 ,操作者必须考虑检查什么点、测定什么地方、刀具什么时候更换为好等问题。对于这样的问题认真动脑筋 ,革新工夹具、安装工具等 ,使前工序的加工品检查能够自动地进行。即在工序内安装防止失误装置 ,发现不合格品。然后 ,将防止失误装置标准化 ,使操作者在交接班的情况下也能够用少的工时作出质量稳定的产品 ,这是很重要的。如果一边进行作业 ,一边进行测量 ,按照项目进行检查 ,不管如何用心 ,一旦疏忽便会造成失败。因此 ,要建造起即使不时时留心 ,当出现了不合格品、作业失误、伤及其他众多的不…     

对GB8053—87的一点建议

对ＧＢ８０５３－８７的一点建议王力兵褚秀玲（山东省文登市广播电视大学）现行ＧＢ８０５３是１９８７年发布实施的计量抽样检验标准，它是以不合格品率为质量指标的验收检验标准。全称是：《不合格品率的计量标准型一次抽样检验程序及表》。该标准中的抽样方案分为两种...     

工序能力指数标准化定义之应用(双侧限)

在双侧规范的情形下,研究了工序能力指数标准化定义的依据;在以不合格品率(p)为质量指标的情形下,不仅证明了p与CP、ε(偏移量)之间的计算公式,而且给出详尽的数值表。此外,还给出了典型的应用示例,供企业参照。     

实行SPC过程控制提高过程能力探究

本文论述了对工序中易出问题的零件实行SPC过程控制，以提高过程能力，达到及时、迅速地预防不合格品的产生及纠正偏离现象。     

统计质量控制在汽车总装中的应用

研究了汽车装配过程的质量控制,用质量控制图实时监控安全螺栓的拧紧过程,对装配过程的导常情况实时报警,并可离线查询装配过程数据,编制了相应的数据库和应用程序。本文采用的控制图主要是不合格品率P控制图和运行图等统计方法提供装配过程控制的决策支持。     

基于工序成本的多元过程能力指数分析

单一的多元过程能力指数在反映企业制造多元质量特性产品能力时存在缺陷,无法反映由于各工序成本的差异而造成的工序能力重要性的差别.基于此,从企业工序质量控制和工序成本关系的角度来分析,构建了基于工序成本修正的多元过程能力指数,反映企业的成本控制能力和产品竞争能力.最后,通过修正得到的多元过程能力指数,一方面优选企业的质量改进或控制方案,另一方面判定企业在同类产品制造中的实际质量控制能力和过程成本损失差异.     

Quality evaluation of internal cylindrical grinding process with multiple quality characteristics for gear products

Gears are among the most crucial components in the transmission systems of machine tools. Gear manufacturing includes a number of processing procedures. The grinding process is an important procedure involving high precision and fairly small grinding surfaces. For this reason, this study aimed at developing a quality assessment model for the internal cylindrical grinding process of gears. The Six Sigma quality indices (SSQIs) were used to directly assess the quality of the internal cylindrical grinding process due to their ability to directly reflect quality level and process yield. Since the process may include nominal-the-best (NTB), larger-the-better (LTB) and smaller-the-better (STB) quality characteristics, so we used the variable transformation method to normalise the specifications of each quality characteristic for the convenient and effective management and analysis of process performance for multiple quality characteristics. We then constructed a multi-characteristic process quality analysis chart (MPQAC) to simultaneously assess the quality levels of various quality characteristics. Furthermore, the MPQAC can provide references for process improvement. This ensures the quality of internal cylindrical grinding and enhances the quality of gear and machine tool products. Finally, a real-world application and numerical experiments demonstrate the effectiveness and practical applicability of the proposed method.     

核电仪控产品电路板无铅焊接技术研究

为推进产品绿色化,开拓国际市场,应对欧盟RoHS指令,需要推动核电仪控产品电路板无铅焊接工作;采用DOE试验对核电仪控产品的无铅材料的焊接工艺进行了研究和工艺验证,并对无铅工艺产品进行外观、金相、SEM等分析,并研究了温度、环境等对焊接质量的影响.结果表明,在使用Sn-3.0Ag-0.5Cu焊接材料、工艺曲线合适(峰值温度237℃左右,保持时间35 s左右)情况下,可以获得稳定的产品质量.     

Reliability analysis for mechanical parts considering hidden cost via the modified quality loss model

The improvement of mechanical parts inherent reliability has an impact on the reputation and performance of the company. To estimate the inherent reliability of products more conveniently and economically, a hidden quality cost-production cost (HQC-PC) reliability prediction model is put forward. To estimate the hidden quality cost (HQC) of products more accurately, a quadratic exponential quality loss function model is established, which is different from Taguchi's quadratic quality loss function (QLF) and the modified QLFs. In the new quality loss model, the growth rate of quality loss on both sides of the target value is considered. Under the condition that the quality characteristic value obeys normal distribution, the general estimation formulas of HQC in the tolerance range is obtained considering sampling error and the numerical model of inherent reliability is established. The effect of different parameters on the inherent reliability of products is discussed with practical case, such as design and production parameters. Then, the appropriate process capability index (PCI) is selected according to different production processes. The relationship between the HQC-PC reliability prediction model and PCI is derived by a numerical model of inherent reliability. A new analysis method of inherent reliability is proposed.     

Studies on the in vitro and in vivo degradation behavior of amino acid derivative-based organogels

The in vitro degradation behavior of organogel with different gelators based on amino acid was investigated in detail. Two methods were applied in this research: weighting method and high-performance liquid chromatography with evaporative light scattering detection (HPLC-ELSD) method, which was established for the first time. Their degradation behaviors in vivo were investigated by varying the kind and concentration of gelators via subcutaneous implantation. The results showed that the stronger the gelation ability or the higher the gelator concentration, the slower the degradation rate of organogel. Moreover, the organogel prepared by oils with longer alkyl length degraded slower than that of the shorter ones, which also decreased in thermal stability and mechanical strength. The investigation on degradation process showed that the degradation rate was mainly controlled by the collapse of network structure formed by gelators. In conclusion, organogel had a tunable degradation rate through altering the gelator type, oil type and the gelator concentration. It remains a promising candidate for subcutaneous in-situ implant as drug delivery vehicle.     

Effect of rework,rejects and inspection on lot size with work-in-process inventory

The economic order quantity and economic production quantity models are the most commonly used inventory models in production environments for the calculation of optimum lot size. However, these models are based on the unrealistic assumption that every process produces good quality products every time. Moreover, the impact of inspection is neglected in all extended inventory control models involving work in process inventory. By taking both imperfect production and lot size inspection into consideration, this paper presents a more realistic approach for the modelling of optimum lot size and total cost with a focus on the work in process inventory. A mathematical model is derived for optimum lot size based on the minimisation of the average cost. Our approach incorporates the effect of rework, rejects and inspection on work in process inventory. The significant effect of imperfect production and inspection on optimum lot size is evaluated via numerical examples. In comparison to existing models, the proposed model is a more generalised and flexible form of inventory model for independent demands.     

基于拟合优度检验的卷烟卷制过程质量一致性评价

目的 为解决当前卷烟卷制评价方式粗放，通常只重视质量结果而忽视过程质量差异的问题，建立同一牌号卷烟在不同机台、不同班组的加工质量一致性综合评价方法。方法 采用拟合优度检验的方法建立卷烟卷制过程质量一致性评价方法，并采用判断矩阵确定质量特性的权重，并进行质量一致性综合评价。结果 选取黄金叶(乐途)品牌在卷烟卷制过程中的在线监测数据，运用新构建的评价模型对3个机台的烟支质量、吸阻、端部落丝等7个质量特性进行质量一致性综合评价，并有效识别出了机台之间存在的质量差异。结论 该综合评价方法能够对卷烟多加工过程之间的差异进行有效识别和评价，实现了由结果评价向过程评价的转变，具有良好的评价能力和可操作性。     

两种生产工艺对H65黄铜管组织与性能的影响

对挤压法和"连铸-冷轧"法两种工艺生产的H65黄铜管的组织与性能进行了综合对比研究。结果表明:两种工艺下H65黄铜管成品平均晶粒尺寸相差较小,挤压法工艺约14μm,"连铸-冷轧"法工艺约18μm;"连铸-冷轧"法成品管抗拉强度为335MPa,伸长率为61%,硬度为84.7HV1.0,挤压法成品管分别为360MPa,67.5%和82.6HV1.0,均达国标要求;挤压法成品管平均偏心率约12.5%,而"连铸-冷轧"法成品管偏心率仅为6.2%,且综合成材率较挤压法提高了11%。分析表明,高效短流程的"连铸-冷轧"法H65黄铜管加工工艺具有良好的发展前景。     

Improving quality in iron casting by optimizing sand recycling

Two previous studies of the application of the techniques of information technology and statistics to the relatively low-level records of a semi-automated iron foundry have been made. Each has contributed to better knowledge and understanding of variables of the casting process, in the course of solving a specific problem. Encouraged by the enthusiasm for and quality of record keeping evident during the studies, it was decided to use the same investigative approach to make a deliberate search for any opportunity that might exist for improving the quality and/or productivity of green sand moulding. Data collected over a period of ten weeks were analysed under four broad headings: products, input materials, process operations and control of process variables. A comparison of production figures from the start and finish of the datum period revealed a reduction in the mould rejection rate of 40 per cent with reductions in inputs of new sand and bentonite of 42 and 12 per cent, respectively. The seemingly onerous task of good process record keeping had proved to present an opportunity in disguise.     

T2铜箔空化射流柔性微冲裁机理分析

目的 分析针对不同形状特征时空化射流箔材微冲裁工艺的加工效果,确定工艺参数的影响规律。方法 通过在3种模具（正三角形、正六边形以及圆形模具）下设计6种特征尺寸,分析空化射流对不同厚度T2铜箔的冲裁加工效果,同时通过单因素实验法确定空化射流的入射压力、喷孔直径以及靶距3种工艺参数对微冲裁加工能力与成形质量的影响规律,记录不同工艺参数下T2铜箔的最大可冲裁箔厚。结果 T2铜箔的最大可冲裁箔厚与凹模特征尺寸之间存在线性关系,并且入射压力的增大可显著提高空化射流微冲裁工艺的最大可冲裁箔厚,然而,过大的喷孔直径与靶距均会造成最大可冲裁箔厚下降。通过对实验结果进行表征,发现正多边形冲裁件在边角处会出现裂纹、撕裂等缺陷,而圆形冲裁件的冲裁轮廓无明显缺陷,冲裁质量较好。结论 空化射流柔性微冲裁工艺对正多边形冲裁件边角处的加工效果较差,但加工的圆形冲裁件具有良好且均匀的轮廓质量。该工艺的加工能力随入射压力的提高而提高,且在靶距为120 mm、喷孔直径为1.6 mm时较优。