烧结机机尾固定筛的改进

针对烧结机机尾固定筛进料口盲板和筛条易损坏,寿命短,影响正常生产的问题,通过分析机尾固定筛的工况条件,在力求提高性价比的前提下,对其结构和材质进行了改进.改造后机尾固定筛的使用寿命达到1年,实现了与其它设备同步检修的目的.     

On deformation control of dental crowns prepared by titanium powder process

Abstract

This study describes the identification of the main cause of deformation of titanium dental copings prepared by a new powder metallurgy method. The deformation was observed during the process development and needed to be explained to achieve an approved fit. The coping fabrication process was divided into stages to find the main cause of deformation. Each individual stage was investigated to find the cause. Primarily the pressing, milling and sintering steps and the tooth preparation dies (mandrels) were studied. The main cause of the deformation was found to be a deformation of the tooth preparation die during the pressing phase. The other stages were all shown to contribute only slightly or not measurably to the deformation. When using tooth preparation dies of a stronger material (stainless steel) the dies did not deform measurably during cold isostatic pressing and copings of various individual forms with an approved fit could be prepared.     

Swelling during sintering of titanium alloys based on titanium hydride powder

Abstract

Compacts were prepared by pressing titanium and titanium hydride powders mixed with nickel powder and sintering under vacuum. Severe swelling was observed only for compacts based on TiH₂ powder. Pressure changes in the vacuum furnace, dilatometry results and mass loss data all indicate that dehydrogenation of TiH₂ powder compacts occurs at lower temperature than any significant sintering. Swelling appears to have been caused by a contaminant in the TiH₂ powder rather than hydrogen. The onset of severe swelling during heating was associated with the formation of liquid phase as the solidus was crossed. However, some swelling appears to take place under solid state sintering conditions. Various results indicate that the mechanism of swelling is high gas pressure within closed pores. Large pores appear to form by breakage of ligaments between small pores followed by opening of the pore. It appears that the use of (uncontaminated) TiH₂ powder in place of Ti powder would allow the benefit of lower green porosity to be retained during sintering to achieve low sintered porosity.     

热连轧工艺润滑系统的设计与维护

针对工艺润滑系统调试及使用中常见的一些故障及异常情况,通过比较常见的两种工艺润滑系统机上设备布置特点以及对供油系统的设备选型分析,提出了工艺润滑系统中切水板、喷嘴、计量泵以及供油系统、供水系统等设计选型及使用维护中的关注重点及措施。     

机床液压系统常见故障及使用维护方法分析

机床液压系统通常,下含义判断产生故障的原因。本文通过对机床液压系统常见故障进行分析,从机床液压系统振动和噪音、液压系统的冲击、液压系统中的“爬行”、液压泵出现吸空情况、液压系统温度上升五个方面进行介绍,提出诊断方法,并且介绍机床液压系统的使用和维护注意事项,希望可以帮助相关工作人员排除故障问题,保障机床液压系统的正常运作。     

Application of MicroLogixTM 1200 PLC in Battery OCV Test

The application of MicroLogixTM 1200 PLC made by American AB Company in battery automatic production line located in Inner Mongolia Rare Earth Ovonic High-Power MH/Ni Battery Co., Ltd was introduced.OCV namely open circuit voltage could be somewhat different because of the build materials of negative electrode, positive electrode and electrolyte.So OCV test can check the voltage value of electrolyte filled cells and figure out if the value is within the process specification.MicroLogixTM 1200 relay output type PLC, DeviceNet communication card, variable speed driver, Panelview 1000 color touch screen and some other hardwares were chosen.Then programme by using RSLOGIX500 software, a flexible and skillful use of shift and XOR command in PLC system can make the equipments realize the high automation.Through DeviceNet network based on CAN and with the advantages of quick response and high reliability transmit the information to supervise and control master panel, the system with these components can successfully realize proceeding the battery OCV test and control.The equipments are running stably, locating and test accuracy satisfy the process request.     

Giant T wave inversion associated with severe aortic regurgitation

In 1978, the Food and Drug Administration (FDA), developed a generic anesthesia equipment preuse checklist. The checklist was first released by the FDA in August 1986 and endorsed by the American Association of Nurse Anesthetists on October 18, 1986. The FDA checklist was revised in 1992 to improve the abilities of anesthesia providers to detect machine faults. In the present study, the investigators attempted to determine the effectiveness of the revised FDA checklist in detection of anesthesia machine faults as compared to providers' usual methods. Whereas no published study of preanesthesia safety inspection had been performed since the revision of the FDA checklist, the authors compared the detection abilities of anesthesia providers before and after inclusion of the revised FDA checklist. Twenty-two anesthesia providers were tested to compare the number of prearranged anesthesia machine faults that could be detected with (1) their usual checkout methods, and (2) with the revised FDA checklist. Data describing the subjects' fault detection abilities were analyzed using the t test for paired observation (P value < 0.05 considered significant). Statistical analysis revealed no significant difference (P = 0.479) when subjects used the FDA checklist and when they used their usual method. Use of the FDA machine checklist was no more effective than the provider's usual method in discovering machine faults. When using their normal method, 54.5% of providers did not discover more than 50% of programmed faults. Approximately 40.9% of providers who used the revised FDA checklist did not discover over 50% of programmed faults.     

Component analysis and stimulus control assessment of a behavior deceleration treatment package

A treatment package that included two setting condition manipulations and visual occlusion was implemented to gain control over the high-intensity screaming and whining of a 16-year-old female with developmental disabilities. The study included an analysis of the individual and combined components of the treatment package and a stimulus control analysis of three salient features of the visual occlusion apparatus (i.e., opaque screen, secured helmet, and cranial pressure). Results showed that the treatment package occasioned a deceleration in the two targeted vocal behaviors and a reduction in the amount of time the participant was required to wear the occlusion apparatus. An analysis of the apparatus suggested that the critical element needed to control inappropriate vocalizations appeared to be cranial pressure, which was naturally produced by the helmet. Consequently, the helmet was eliminated and cranial pressure was produced by a woman's headband. Follow-up data, collected 1, 2, and 3 months after termination of systematic intervention, revealed near-zero levels of screaming and whining behaviors. A 9-month follow-up investigation involving the removal and subsequent reinstatement of the headband procedure supported the use of the headband for the maintenance of behavioral gains.     

Numerical simulation of powder compaction for two multilevel ferrous parts,including powder characterisation and experimental validation

Abstract

The paper presents a summary of two case studies that were carried out by the scientific team in the Thematic Network PM Modnet. During the life of this project, the compaction of complex multilevel ferrous components was investigated. These formed a vehicle to explore methods to characterise the yield and friction properties of the powder, perform simulation of the compression stage of the forming process, complete experimental trials, and compare experimental and simulated results. Density comparisons were made with results from Archimedes, quantitative metallography, and computerised tomography and force levels were compared with recordings from the pressing trials. The results highlight differences between equipment and experimental techniques used in characterising powders. They also show that hardness, metallographic analysis, and computerised tomography may be used to measure density variations throughout the compact. The prediction of density variation was reasonably consistent when using different simulations, whereas punch force prediction showed good consistency. It was found that predicted and measured density distributions agree within 0·05 to 0·5 g cm^-3 and that punch force levels may be predicted within 10 to 30%. The study effectively establishes a benchmark with which to compare and improve future simulations.     

沃尔沃铰卡典型故障探讨

作为世界知名工程机械设备制造商,沃尔沃旗下的铰接式卡车,由于采用了成熟的电、液、气、机一体化设计,使得设备具有生产能力最大化所需要的动力和耐用性,比较适合于全天候露天采矿作业,目前已经被很多国内外矿山接受和使用,但在设备维护维修方面还存在薄弱环节。针对沃尔沃铰接式卡车常见的故障进行分析;对其维修过程中容易出现的几种问题进行了探讨,同时对维修现状提出建议。     

Routine Highway Bridge Inspection Condition Documentation Accuracy and Reliability

Routine inspection is the most common form of highway bridge inspection to satisfy the requirements of the National Bridge Inspection Standards. The accuracy and reliability of documentation generated during these inspections are critical to the allocation of Department of Transportation construction, maintenance, and rehabilitation resources. Routine inspections are typically completed using only the visual inspection technique and rely heavily on subjective assessments made by bridge inspectors. In light of this, and given the fact that visual inspection may have other limitations that influence its reliability, the Federal Highway Administration initiated an investigation to examine the reliability of visual inspection as it is currently applied to bridges in the United States. This paper will summarize results from this study related to the accuracy and reliability of routine inspection documentation. A number of important conclusions were developed from the experimental study. Generally, it was found that all structural condition documentation is collected with significant variability. Specifically, 95% of primary element condition ratings for individual bridge components will vary within two rating points of the average and only 68% will vary within one point. Documentation generally collected to support condition ratings also has significant variability as exemplified by the number and types of field notes and photographs taken by inspectors. With respect to the use of element-level inspections, it was found that element usage was generally consistent with the Commonly Recognized Element Guide. However, there is significant variability in the condition state assignments of those elements and in some cases the condition states are not applied correctly to particular elements.     

Titanium–hydroxyapatite composite biomaterial for dental implants

Abstract

The objective of the present study was to investigate high velocity compaction of titanium powder and to prepare a dense composite biomaterial of titanium and hydroxyapatite with the purpose of forming dental components with improved early healing properties. A high purity titanium powder was compacted using high velocity compaction to study the density distribution. Then, a titanium–hydroxyapatite composite was prepared by mixing titanium powders and hydroxyapatite grains. Dental implant components were formed from the high velocity compacted specimens, exposing the hydroxyapatite grains at the component surface. The green density reached more than 98·5% after more than one impact. The composite was heated to 500°C, enough to bind the titanium grains, but to avoid observable reactions. Compacted pure titanium could be sintered to full density. The heated composite material reached 99% density, no reaction was observed between titanium and hydroxyapatite, and the composite material could be formed into dental implants.     

基于数控机床设备故障领域的命名实体识别

为了给数控机床故障的精准诊断提供保障，延长数控机床使用周期，以数控机床历史维修记录为研究对象，对数控机床设备故障领域的命名实体识别进行了研究。在分析历史维修记录中的故障描述特点后，提出了一种基于双向长短期记忆网络（Bidirectional long short-term memory, BLSTM）与具有回路的条件随机场（Conditional random field with loop, L-CRF）相结合的命名实体识别方法。首先，对输入语句进行分词和标注，使用Word2vec中的Skip-gram模型对标注语料进行预训练，将其生成的字向量通过词嵌入层转化为字向量序列；然后，将字向量序列输入BLSTM学习长期依赖信息；最后将句子表达输入L-CRF获取全局最优序列。实验结果表明，该方法明显优于其他命名实体识别方法，为数控机床设备的智能检修与实时诊断任务打下了坚实的基础。      

Development of model to predict condition monitoring interval times

Abstract

Condition monitoring intervals are usually set at fixed intervals of length typically set by a mixture of British Standards, manufacturer's recommendations, and personal experience. These rather ad hoc methods have little scientific basis. A recently developed condition based maintenance model is described which utilises reliability data combined with condition monitoring measurements. This model provides the necessary basis to optimise condition monitoring intervals. Results obtained using artificial data, based on typical machines found in a hot strip mill, show how the model can be used as part of a condition based maintenance strategy.     

烧结提产综合治理措施

唐山国丰一炼铁为了给高炉提供足够的烧结矿,对烧结机进行了升级改造和综合治理.分析了环冷机漏风、台车跑偏、皮带跑偏的原因并提出了改进措施,同时对冷筛激振器和皮带尼龙棒进行了改型,加强了台车线下维护和大中修质量,减少了烧结机非计划停机,提高了烧结产量.     

A philosophical approach to treatment machine maintenance and breakdown

Planned preventative maintenance (PPM), quality control (QC) checks and breakdown all contribute to the down-time of a radiotherapy treatment machine. Low levels of machine availability are unacceptable both clinically and financially. Clinical data demonstrate that, for many tumours, interruptions to treatment will result in reduced local control. Reductions to the gaps in treatment can be achieved by patient interchange between machines. Maintaining the maximum possible machine availability will reduce the potential for errors associated with the transfer of patients between machines, and reduce the cost of treatment. Practices for routine PPM and QC vary between hospitals. In this report, a rationale for breakdown and maintenance will be described. Based on the faults experienced on a Philips SL 75-5 and a Philips SL25 over a period of 3 years, the workload associated with routine maintenance and quality control are presented and the additional work associated with breakdown discussed. Faults have been categorized on a scale between catastrophe and maintainability. A demonstration of how this analysis can be used to assess the cost-benefits of proposed changes in working patterns by the extension or reduction of maintenance periods is provided. The results indicated that no gain would be made in changing from a 1-day to a 2-day per month PPM schedule.     

KY-310B型牙轮钻机湿式除尘系统改进

文章阐述了KY-310B型牙轮钻机湿式除尘系统的构成及工作原理,针对其在使用过程中存在的问题,提出了改进方法,改进后,使用效果良好,对其他矿山同类钻机的高效使用具有借鉴作用。     

风机基础松动故障诊断实践

根据故障特征并采用先进、可靠、实用的诊断方法,对烧结机主抽风机和干熄焦除尘风机机组的机械松动故障,进行了现场诊断分析,准确判断出设备运行状况劣化的振动原因,为及时有效地指导实施维修,奠定了坚实的技术基础。     

Effect of residual pressure on vacuum sintering of Ti–Ni alloys

Abstract

In earlier work the authors examined the sintering of Ti–Ni alloys by means of dilatometry of mixed elemental powders. Some notable differences were observed when heat treatments were carried out using a vacuum tube furnace rather than the dilatometer: higher sintered density was achieved due to a combination of lower heating rate and lower residual pressure, and swelling during liquid phase sintering was greatly reduced. This observation is consistent with the idea that gas pressure within closed pores causes swelling during liquid phase sintering and retardation of shrinkage in solid state sintering. In addition to the results of measurements of density and open and closed porosity as a function of Ni content and sintering temperature, macrographs and optical micrographs of the sintered compacts are presented, and the effects of heating rate and compaction pressure are described.     

旋转机械设备状态预警与维修优化

旋转机械设备的维修策略对于维护机械设备运行状态,保障产品生产质量有着重要意义,并且直接影响企业经济效益.频繁维修虽可以保障设备状态,但随之会带来高昂的维修成本;检修周期过长虽然可以降低维修次数,减少维修成本,但是设备状态却难以保证.本文提出了一种基于峭度指标的故障预警方法以及基于模糊C均值方法的实时维修策略优化方法.通过监测峭度指标变化,可以成功捕捉机械设备的早期故障特征,再使用模糊C均值方法,评估设备状态,将其结果视为设备运行可靠性指标,根据企业效益最优化的维修建议准则,对设备的维修策略做出实时建议.对某钢厂的设备状态监测数据分析验证,结果表明,本文提出的基于实时维修策略优化方法的维修建议更加适用于现场设备的管理,节约了监测成本,使得企业效益更优.