热镀锌锅过早开裂失效的原因诊断

镀锌锅的过早腐蚀和失效开裂 ,导致镀锌成本的上升和生产的极大损失。针对某单位的锌锅在投入使用时 ,即产生开裂失效的现象 ,通过对锌锅原始断口形貌和金相组织 ,X荧光光谱全成分分析、拉伸力学性能和拉伸断口形貌及锌锅受力情况的数值模拟等的研究结果表明 :锌锅钢板中存在的沿晶渗碳体是锌锅过早开裂失效的重要原因     

高速纸机烘缸轴承过早失效分析及改善研究

利用振动监测与故障诊断技术和油品分析技术对高速纸机前干燥部烘缸轴承进行监测跟踪,并对烘缸轴承的过早失效机理进行了研究。结果表明:烘缸轴承对润滑要求非常苟刻;润滑失效可致其过早失效;在不改变润滑油型号前提下,增大烘缸轴承座进油、排油温差,增大循环润滑油流量,促进带走烘缸轴承运行产生的热量,使润滑油工作实际黏度相对增加,有利于润滑油膜形成,从而延长烘缸轴承使用寿命。     

袋式除尘器滤料失效形式及原因分析

随着袋式除尘器使用范围的不断扩大,滤袋作为袋式除尘系统的核心部件,滤袋失效越来越引起行业的重视。作为整个袋式除尘器系统的核心部件,滤袋的过早失效影响整个除尘系统的正常作业,增加整体的运行成本。本文通过对实际工况的总结,总结滤袋失效的几种常见原因。     

不锈钢烘筒裂纹破坏的分析研究

本文阐述的是对１Ｃｒ１８Ｎｉ９Ｔｉ奥氏体不锈钢烘筒过早失效进行的剖析研究，结果证实是由于应力腐蚀裂纹所致。     

GL3V磨粉机同步带失效成因及解决方法

1 同步带失效成因 GL3V型磨粉机(意大利高尔菲特公司)采用同步带传动机构,具有传动结构简单、拆装方便、运转平稳、传动比准确、噪声低、不需润滑、安全等优点。然而同步带过早失效及其昂贵的价格一直是令人头疼的问题。我厂使用的齿楔带型号为RPP1760-8M-40,其中带长(圆周)1760mm、齿中心距为8mm、带宽40mm。一面是11槽的楔带,一面是220个圆底方齿。它在前路渣心磨易过早失效。最初是靠近轴承端的那根同步带搓皮、断裂,最后导致3根带全部     

植物油厂滚动轴承失效的原因及预防措施

在植物油厂,滚动轴承应用很广泛。但在生产过程中滚动轴承的失效现象经常发生,滚动轴承的失效不仅增加了设备维修费用,而且由于停车造成的经济损失也是很大的。为此,本文试图根据植物油厂滚动轴承失效的形式,分析其失效的原因,并提出预防措施,供同志们参考。 一、滚动轴承失效的原因 1.疲劳点蚀 滚动轴承在安装、维护、润滑正常的情况下,绝大部分轴承都因疲劳点蚀(即滚动体、内外圈上产生麻坑)而失效。在确定轴承寿命时,设计者都是以轴承的疲劳强度为依据确定的。所以,这种失效形式为正常现象。但在安装时,若两轴承孔的不同轴度误差过大,将导致轴承受力不均匀,使局部应力增大,降低了轴承的疲劳强度,而过早出现疲劳点蚀现象,使轴承的使用寿命降低。     

简析如何提高模具寿命

模具损坏的形式有事故损坏和正常损坏两大类。文章重点分析模具正常损坏中过早失效的原因以及采取的措施,可根据加工材料和生产批量、零件形状、工艺流程选择模具材料、热处理工艺、模具表面渗入其它元素、喷涂润滑剂等方法来提高模具寿命。     

A513型细纱机罗拉轴承失效分析

罗拉轴承是纺机上的主要零件。一台416锭的A513型细纱机需要LZ16.5罗拉轴承164只。经试验轴承在短期(最短的二、三个月)运转中,便出现大量磨损、损坏的现象,使罗拉和轴承过早的丧失精度而失效。经过对全列罗拉的受力及损坏轴承的分析,找出了轴承端面的微动腐蚀磨损(Frett-ing Corrosion)和滚针、跑道的疲劳剥落是轴承失效的主要原因。在台架试验的基础上提出了一些减少这类损坏的措施,并经纺纱厂运转证明这些措施是有效的。     

车辆控制臂疲劳损伤分析与寿命预测探讨

近年来,随着社会的不断进步以及经济的迅猛发展,人民生活水平显著提升,车辆利用率逐年攀升,其重要性不容忽视。控制臂作为汽车悬挂系统的传力及导向元件,在整个车辆系统占据着关键的应用地位,其所具有的性能特性直接影响着汽车悬挂系统的综合性能,针对车辆构件由于疲劳问题产生过早失效破坏,造成失效概率大幅度增加的问题,为起到良好的预防作用,使得车辆疲劳耐久性能得以优化提升,则需针对车辆控制臂疲劳损伤分析及寿命预测进行简要探讨。     

尼龙蜗杆

蜗轮蜗杆副的设计,一般都用钢料作蜗杆并对其齿面作淬火或渗碳淬火处理,硬度都在 RO45以上,只有极少数转速很低的手动蜗杆齿面是不作处理的。蜗轮则用铸铁、青铜或尼龙等一类耐磨而强度较低的材料。这样设计的目的是为了提高蜗杆的使用寿命,以免过早失效。     

纺纱牵伸胶辊胶圈应用技术概要

阐述棉纺牵伸胶辊、胶圈的应用技术和牵伸原理,重点探讨了胶辊、胶圈的牵伸工艺特性及其合理配置、胶辊制作、周期管理、质量管理、使用管理、产品缺陷与其机械波分析、纺纱环境和挡车工操作水平对纺纱性能的影响,提出胶辊、胶圈有关机件的质量要求等。     

赛络纺纱钢领、钢丝圈的选配实践

为了提高赛络纺纱成纱质量,减少细纱断头,从钢领、钢丝圈的种类,卷绕过程中对纺纱的影响及其运动配合等诸多因素出发,论述了钢领、钢丝圈的选配原则,重点阐述了赛络纺纱钢丝圈运动形态的变化及钢领、钢丝圈的选配要求,通过纯棉、非棉纤维纺纱的选配实践,指出赛络纺纱线毛羽少,结构紧密,应根据纺纱纤维性能和纺纱特点,以纱线通道通畅降毛羽、运行平稳少断头、散热良好延长使用寿命为原则对钢领、钢丝圈进行选配。     

高校宝石及材料工艺学专业的构建研究

通过回顾高校宝石及材料工艺学专业的创建历程,深入探讨了该专业未来发展所面临的、深层次的理论问题,即学科属性与文化背景,学科构成与知识内涵,学科方向与实践定位,学科任务与社会功能。在此基础上,建立了多层次技术教育的社会功能模型,由此推断：高校中的宝石及材料工艺学专业属于多层次技术教育中的高等职业技术教育。同时,还构建了该专业的技术教育的社会功能模型和学科构成模型,进一步确立了该专业的社会实践定位。     

服装的空间形态辨析

从分析服装空间形态的构成要素入手,通过中西方服装空间形态的比较,阐述服装形态在空间关系上的相关问题,对服装的形态类型、要素构成和内外构成等方面进行了较详细的探讨和分析,印证了人类在同一服装原生状态基础上所产生的造型差异,是由于不同人对服装空间形态的认识方式和服饰审美观念存在差异所致。认为无论是东方式的平面构成或是西方式的立体构成,服装的形态都是在不同时代、不同地域和文化中被人们以不同的空间构成方式创造出来的。辨析服装空间形态及其构成方式,为现代服装的造型设计提供了一条丰富服装创意思维的现实途径。     

Human risk assessment and TEFs

The concept of toxic equivalency factors (TEFs) has been developed to facilitate risk assessment and regulatory control of exposure to complex PCDD, PCDF and PCB mixtures. Recently the European Centre for Environment and Health of the World Health Organization (WHO-ECEH) and the International Programme on Chemical Safety (IPCS) jointly reevaluated the TEFs of PCDDs, PCDFs and dioxin-like PCBs for mammals and derived consensus TEFs for birds and fish (Stockholm, 1997). From a mechanistic point of view it can be concluded that, although the quantitative response will vary depending on the congener involved, the occurrence of a common mechanism (binding to the Ah receptor) legitimates the use of the TEF concept across species. But there also is criticism regarding the TEF concept. Pharmacokinetic differences between species can significantly influence the TEF value, and uncertainties due to additive or nonadditive interactions, to differences in species responsiveness and to differences in the shape of the dose response curve might hamper the derivation of consensus TEF values. In this context it should be noted, however, that using TCDD alone, as the only measure of exposure to dioxin-like PCDDs, PCDFs and PCBs, would severely underestimate the risk from exposure to these compounds. Therefore, it can be concluded that, for pragmatic reasons, the TEF concept remains the most feasible approach for risk assessment purposes, in spite of the uncertainties associated with its use.     

39—THE FLOW OF LIQUID FROM A JET THROUGH A COMPRESSIBLE POROUS LAYER. PART III: THE CHARACTERISTICS OF LIQUID FLOW THROUGH A COMPRESSIBLE LAYER OF LOOSE WOOL

The effects on the conditions of flow of the surface and configurational properties of the fibres in a compressible porous layer are discussed. The characteristics of a layer of wool are evaluated, and its compressibility is determined. It is shown that, when a liquid of initial uniform pressure flows through a compressible porous medium, the pressure gradient within the medium increases with the distance of flow. The resulting pressure drop is found to depend on a function of the ratio of the downstream to the upstream porosity of the compressible medium. Experimental results are reported for permeable flow through various layers of loose wool; these indicate that, when the flow is disturbed turbulent, the pressure drop through the layers is proportional to the square of the filter velocity. This result is not readily apparent from the graphs of pressure drop against filter velocity because of the compressibility of the fibres.     

集体落纱快装纱管用铝杆锭子设计

为提高空纱管安装效率,分析集体落纱细纱机特点,介绍了锭子杆盘结构型式,说明目前国内铝杆锭子多采用支持器弹簧加支持器帽的结构,虽能基本满足集体自动落纱细纱机的生产需要,但仍存在机械手安装空纱管时动作较多、动作精度不高、且易撞到锭子问题,易对锭子造成损坏并缩短锭子使用寿命的缺陷,重点对新设计的快速安装纱管的铝杆锭子的结构及原理进行分析,指出将弹簧支持器帽换成钢珠,可以大大缩短集体落纱细纱机机械手安装空纱管时间、降低对机械手动作精度的要求,且不损坏锭子、不影响锭子使用寿命,实现了节能降耗、安装效率高的目的。     

11—AN INVESTIGATION OF THE AIR-JET BULKING PROCESS

Experiments aimed at investigating the mechanism of the air-jet bulking or texturing process led to an interesting observation that the textured yarn emerging from the venturi was rotating in such a way as would temporarily untwist the yarn while it was in the jet. The indication is that false-twisting (or untwisting) occurs owing to the vorticity of the turbulent air in the wake of the yarn feed needle that bifurcates the air-stream. The various yarn-processing conditions separately affect the amount of false twist inserted. There is evidence to show that the direction of the vortex, and hence of the untwisting action, is dependent on whether the angular displacement of the feed needle from its central position is in a clockwise or anti-clockwise direction. A suggested mechanism of the process based on the untwisting and retwisting of the overfed filaments offers an explanation for the characteristic locked-in loop structure of air-bulked yarns.     

Combined microscopic and dynamic rheological methods for studying the structural breakdown properties of whey protein gels and emulsion filled gels

The microstructural and large deformation rheological properties of model food gels were studied by performing notch propagation tensile testing on the gels using a tensile stage and observing changes in the microstructure of the gels during tensile testing using confocal laser scanning microscopy (CLSM). Heat-set whey protein (WP) gels containing either added sodium caseinate (NaCN) or sunflower oil droplets emulsified with WP or NaCN as the emulsifier protein were prepared in 0 or 50 mM NaCl. The WP gel structure strengthened in the presence of added NaCl and NaCN. The rheological properties of WP gels containing sunflower oil droplets emulsified with WP or NaCN were influenced by the NaCl concentration, oil concentration and extent of oil droplet aggregation in the gel or by the type of emulsifier protein used. During tensile testing, the notch length in all gels increased above a certain critical stress, leading to fracture of the gels through the notch. Also, the microstructural changes in the oil phase of emulsion filled gels subjected to tensile testing were influenced by the structural properties of the WP gel matrix and the proximity of the oil droplet to the fracture path.