单工作部件与可更换修理设备系统的可靠性

研究了工作部件与修理设备系统的可靠性问题．在修理设备的寿命分布是Ｌ阶Ｅｒｌａｎｇ分布的条件下，利用向量Ｍａｒｋｏｖ过程，给出了系统的全部可靠性指标．     

单工作部件与可更换修复设备系统的可靠性

研究了工作部件与修理设备系统的可靠性问题，在修理设备的寿命分布是Ｌ阶Ｅｒｌａｎｇ分布的条件下，利用向量Ｍａｒｋｏｖ过程，给出了系统的全部可靠性指标。     

喷水织造及其产品开发（六）——喷水织造的质量、工艺和设备管理（续）

设备的小修理周期为1年，工作的主要内容是对机器的主要部位进行拆卸，清除积存油污，检查零件磨损情况，更换超过磨损限度的零件，重新进行平整加油，调整各部件相对位置及各工艺参数，并按大小修理接交的技术条件进行验收；面大修理的周期为4年，其主要内容为：如底脚基础未发生松动或损坏，除左侧墙板可不拆外，原则上要全机拆卸，对拆卸的零部件进行清洗，去除积存油污，超过磨损限度者必须更换，并按平整要求进行全机平装，恢复机械性能，并按大小修理接交的技术条件进行验收。     

巧制起轴工具修机事半功倍

DT400型四开自动平台印刷机的送纸摇臂,是通过往复摆动来完成纸张吸送动作的.由于机件作摆动容易产生惯性冲力,使连杆与摇臂主轴连接的定位销因长久作用疲劳而断裂,以致引起部件间错位,失去了正常的作用,给设备的正常生产造成障碍.我厂两台该型设备都曾发生此类毛病,修理难度较大.摇臂定位销断裂之后,应取出残留在轴孔与连杆上的定位销碎节,才能换上新的配件.但由于摇臂轴定位销部件在机座内墙,墙体内十分狭窄,可活动空间小,取销难度较大.为尽快取出断销,应先把主轴拆离墙体.由于缺乏经验,我们在初次拆取主轴过程中,用拉撞、撬、敲等修理技巧,都难以把主轴从墙体上完全分离.     

液压设备的故障诊断方法探讨

通过对我国目前的工程机械进行调查,多数的工程系统和装置都是采用液压的设备。但是液压的设备一旦出现故障,问题就出在液压设备部件的内部。液压设备的元件体积小,拆卸也不方便,所以,在修理液压设备的部件时经常会遇到各种各样的困难,给现场的修理人员带来各种修理障碍。文章从日常生活中液压设备出现的各种故障进行分析和探讨,结合理论知识和实践经验,对液压设备的故障诊断步骤判断方法和策略技巧进行总结。希望能为液压设备的管理人员提供排除和解除障碍的经验。     

台车安装工作法

台车连续运转一定时期后,需进行平装。通过平装,消除零件在运转中的变形和走动,修理或更换磨损的零件,使机器符合生产与安全的要求。台车的平装与其它针织机一样,包括零、部件的修理和机器的安装。对零、部件的修理要求随各厂机加工条件、备件情况以及技术水平不同而异。所以,在本文中,仅介绍台车安装的工作法。台车的安装主要分拆车与装车两部分。为了保证安装的准确,使用一些工具。先介绍使用的主要工具。     

离散时间下可多重休假的冷贮备可修系统的可靠性分析

在时间参数为离散的条件下,研究修理工可多重休假和转换开关完全可靠的两不同型部件的冷贮备可修系统。假设两不同部件的寿命均服从几何分布、修理工的维修时间和休假时间均服从一般离散型分布,引入三维离散向量,建立新的马尔科夫过程,建立模型,并利用Z变换进行求解,求得系统的稳态可用度、稳态失效频度、稳态等待维修概率、稳态修理工空闲的概率和休假概率、可靠度和首次平均故障前时间。     

YF172滤棒固化储存输送装置的设计应用

滤棒自动生产线的滤棒固化储存装置在使用中存在两个问题:①固化储存库结构不合理,当输送带磨损需要更换时,安装维修不便;②滤棒固化储存装置与其他设备对接时,需要现场配装安装孔,加工精度低,且安装调度时间长.为此,研制了YF172型滤棒固化储存输送装置.该装置主要采用了悬臂结构固化储存库和悬臂式接口部件.实际应用结果表明,①YF172型采用的悬臂结构固化储存库除去了前立柱的阻挡,结构简单合理,方便了磨损输送带的更换;②可调式悬臂结构的接口部件,伸入到对接机中的悬臂长度可在0～65 mm内连续调整,有效解决了固化储存装置与设备的对接问题,不需在安装现场配做安装孔,安装调试时间由原来的1 d左右缩短到2 h,且提高了设备的安装精度.     

M1432A磨床砂轮主轴部件的修理及调整

在现代制造业发展进程中,磨床也逐渐呈现出高精度、重磨削以及高转速发展方向,在M1432A磨床运行过程中,也需要采用正确修理方式且对其合理调整,以能够确保M1432A磨床砂轮主轴的正常运行,提升系统精度,减少设备磨损,对于保障设备应用经济效益具有重要作用。本次则在对M1432A磨床砂轮主轴部件常见问题分析中,对其修理和调整技术展开分析,以为M1432A磨床砂轮主轴部件修理和调整提供相关建议。     

波兰哈切诺夫国营农机站

哈切诺夫农机站,是波兰华沙省按专业分工的唯一的发动机修理厂。有职工250人,年修理二缸发动机5500～6000台,厂房面积为3000平方米。他们的修理方式可归纳为:三线两间一试验。一线是拆卸清洗线。这条线有三台清洗机,一次碱水清洗部件油垢,两次热水清洗零件,然后进行分类、挑选。将可修理的零件分别送到各个修理线去。     

Reliability and maintainability analysis to improve the operation of the limoncello production line

The reliability, maintainability, failure rate and repair rate models of a limoncello automated production line for a period of 8 months at machine and entire line level were carried out. It was pointed out that (i) the real operating time of the limoncello production line (LPL) is 89.35%, whereas for the rest 10.65%, the LPL is under repair, (ii) the Weibull distribution provided the best fit of the failure data for the LPL to describe the time‐between‐failures (TBFs), whereas the time‐to‐repairs (TTRs) are lognormal distributed, and (iii) the failure rate of the production line increases, implying that the current maintenance strategy is not adequate and must be improved. This particular methodology can also be utilised in the beverage industry sector by the machinery manufacturers and the manufacturers of bottled products to improve the design and operation management of the bottling production line.     

Fluid milk processing costs: current state and comparisons

An economic-engineering model is used to derive the theoretically minimum cost of processing and distributing fluid white milk for the state of Maine. This model represents a state-of-the-art milk processing facility and is used to evaluate three questions: 1) the components of total processing costs; 2) whether the cost of milk processing declines with increasing plant size; and 3) the minimum processing volume to financially justify inplant blow-molding technology. The model indicates that significant savings in per-container processing costs can be achieved by increasing plant size. However, distribution costs, related to the geographical distribution of consumer demand and plant location in the state of Maine do not favor large centralized plants. In addition, this model is compared with results published in 1993 to evaluate cost trends over a 7-yr period. The model indicates import shifts to more technologically advanced processing equipment and a dramatic increase in labor costs. Overall, processing costs have risen 2.9% annually above the rate of inflation. Dairies that are unable to respond to increased labor costs through capital investment and expansion will likely find it more difficult to remain competitive in the milk processing industry.     

Incorporating economies of scale into facility location problems in carpet recycling

The Carpet America Recovery Effort (CARE) set a goal to divert 40% of used carpet from landfills in the United States by 2012, but only achieved a 10% diversion rate. To achieve the 40% diversion rate, approximately 1.4 billion lbs would need to have been diverted. Diverting this significant quantity may require the design of a larger, more effective reverse logistics network to process the used materials. A new facility location heuristic originally developed for the forward distribution of products is applied to the reverse logistics system for carpet recycling. The objective is to locate an unknown number of carpet recycling facilities to minimize the total cost. The model includes transportation costs, as well as fixed facility and processing costs at the recycling plant, the latter exhibiting economies of scale (EOS) as the facility size increases. We evaluate the model using data from the CARE collection network in the continental United States and compare these findings to models that assume a significant increase in collection locations and rates to meet specific carpet diversion targets. We show the impact of EOS of the recycling facilities on the solution structure, as well as the impact that collection volumes have on the solution.     

Finite element modelling of the mechanical behaviour of vitreous starch/protein composite

This study deals with the identification of the complete set of mechanical parameters associated to elasticity, plasticity and failure of starch–zein composites. The approach is based on three-point bending experiments and a finite element (FE) simulation approach. FE simulation of three-point bending test is implemented using a simple elastoplastic model. The identification of the mechanical parameters is handled using an optimisation technique based on a error-gradient method. The purpose of the optimisation is to compute the set of mechanical parameters that makes the best match between the FE and the experimental results. In the first linear part of the force–deflection curve, a unique Young’s modulus value is predicted assuming isotropic behaviour for all studied samples. In the plasticity part, two quantities namely tangent modulus and yield stress are suggested to describe the plasticity behaviour of the starchy composites. Failure possibility is assessed using maximum strain criterion, where failure probability distribution within the sample is computed. The predicted results show that the simple elastoplastic model is a realistic model to describe the mechanical behaviour of the starchy composite up to failure. Different distributions of failure probability are predicted depending on which strain component is used to assess the failure possibility.     

WZZ-2S旋光仪故障维修特例

通过2则WZZ-2S旋光仪测量时不工作,测量显示不准确特殊故障的维修过程,向仪器维修人员介绍快捷检测同类仪器故障的检修方法.     

11—A STUDY OF YARN TORQUE AND ITS DEPENDENCE ON THE DISTRIBUTION OF FIBRE TENSILE STRESS IN THE YARN PART I: THEORETICAL ANALYSIS

The torque generated during yarn-twisting is considered to have three components, due, respectively, to fibre torsion, fibre-bending, and the internal fibre tensile and compressive stresses within the yarn. An analysis of the yarn torque generated by fibre torsion will be given in a later paper, and the component due to fibre-bending has been evaluated by other authors. It is proposed that the nature of the fibre tensile-stress distribution within a yarn is likely to be the most influential factor governing the magnitude of yarn torque. The distribution of stress, as a function of the fibre position in the yarn, depends largely on the facility with which fibres can migrate throughout the yarn cross-section. In this paper, two limiting forms of fibre geometry are considered: no migration, and complete fibre equivalence as a direct consequence of migration. For each case, the fibre-stress distribution is analysed, and the component of yarn torque due to these stresses is derived.     

Kinetochores,cohesin, and DNA breaks: Controlling meiotic recombination within pericentromeres

In meiosis, DNA break formation and repair are essential for the formation of crossovers between homologous chromosomes. Without crossover formation, faithful meiotic chromosome segregation and sexual reproduction cannot occur. Crossover formation is initiated by the programmed, meiosis-specific introduction of numerous DNA double-strand breaks, after which specific repair pathways promote recombination between homologous chromosomes. Despite its crucial nature, meiotic recombination is fraud with danger: When positioned or repaired inappropriately, DNA breaks can have catastrophic consequences on genome stability of the resulting gametes. As such, DNA break formation and repair needs to be carefully controlled. Within centromeres and surrounding regions (i.e., pericentromeres), meiotic crossover recombination is repressed in organisms ranging from yeast to humans, and a failure to do so is implicated in chromosome missegregation and developmental aneuploidy. (Peri)centromere sequence identity and organization diverge considerably across eukaryotes, yet suppression of meiotic DNA break formation and repair appear universal. Here, we discuss emerging work that has used budding and fission yeast systems to study the mechanisms underlying pericentromeric suppression of DNA break formation and repair. We particularly highlight a role for the kinetochore, a universally conserved, centromere-associated structure essential for chromosome segregation, in suppressing (peri)centromeric DNA break formation and repair. We discuss the current understanding of kinetochore-associated and chromosomal factors involved in this regulation and suggest future avenues of research.