玩具小模数塑料齿轮参数化设计及有限元分析

针对玩具小模数塑料齿轮在工作过程中经常会出现轮齿折断的问题,提出了一种对该种塑料齿轮几何尺寸进行精确设计的新方法(在该方法中考虑到了模塑齿轮收缩率对齿轮型腔参数设计的影响)。同时利用ANSYS Workbench软件对两种分别由传统设计方法和新方法设计得到的齿轮进行了对比,验证了新方法的可行性,从而为玩具小模数塑料齿轮参数化设计提供一定参考。     

JZ1406齿轮副损坏原因分析及检修措施

列举JZ1406齿轮副多次损坏的情况,分析造成轮齿折断的主要外因是安装侧隙过大,造成过大的交变应力;安装不平行造成齿轮偏载,引起轮齿局部过载。同时经强度校核,说明按传统的安全系数设计法设计的JZ1406,齿轮安全系数偏低,是轮齿疲劳折断或瞬时过载折断的内因。针对主要外部原因,采取了齿轮平行度调整及安装特制偏心瓦以调整啮合侧隙的有效检修措施。     

磨煤机故障案例分析及处理

<正>中石化齐鲁分公司第二化肥厂采用的溢流型磨煤机(Φ4 000 mm×5 800 mm,1开1备)自2008年10月投运以来,故障频发,虽然没有发生全系统停车事故,但磨煤机频繁切换会造成煤浆大量浪费和气化炉减负荷运行。1齿轮磨损故障(1)故障现象主动小齿轮轴轴承温度持续升高,变速箱、小齿轮轴承箱和机箱振动增大,紧急停车。(2)原因分析经初步检查,发现大、小齿轮喷雾润滑装置堵     

陶瓷厂球磨机齿轮减速箱倒频谱故障诊断法

介绍了倒频谱分析的基本原理及在齿轮减速箱故障诊断中的应用.鉴于球磨机齿轮减速箱振动信号中调制源多、频率成分复杂,功率谱中存在大量的非对称边频带及周期性结构信号导致故障识别工作困难的问题,运用倒频谱分析法对其进行故障诊断,它能将功率谱上成族的边频带谱线简化为单根谱线,分离和提取出密集泛频信号中的周期成分、多成分边频,快速准确诊断球磨机齿轮减速箱中零件的故障.     

基于倒频谱分析的球磨机减速机故障诊断

介绍了倒频谱分析的基本原理及在齿轮减速箱故障诊断中的应用。鉴于球磨机齿轮减速箱振动信号中调制源多、频率成分复杂，功率谱中存在大量的非对称边频带及周期性结构信号导致故障识别工作困难的问题，运用倒频谱分析法对其进行故障诊断，它能将功率谱上成族的边频带谱线简化为单根谱线，分离和提取出密集泛频信号中的周期成分、多成分边频，快速准确诊断球磨机齿轮减速箱中零件的故障。     

三复合挤出机的机械故障及其处理

介绍了从德国进口的三复合挤出机的螺杆、喂料机筒及其旁压辊装置、挤出机筒和减速箱等重要部件在使用过程中出现的主要机械故障,分析了产生的原因,并提出了相应的修复方法,螺杆的磨损一般为自然磨损,只需在螺棱表面部位用堆焊焊条ＳＨ－Ｄ２２７堆焊上一层硬质耐磨合金即可,喂料机筒,挤出机筒和减速箱齿轮轴及齿轮则需进行技术处理后重新制做     

ZD70减速机轴承间隙调整的小窍门

ZD70减速机是Φ2．2×6．5m磨机的配套设备,减速机所用轴承全部为圆锥滚子轴承,减速机长时间运转会产生正常磨损,致使轴承径向和轴向间隙增大。由于间隙的增大,减速机运转将产生噪音且引起机体震动,从而导致磨机受到不均匀的冲击。若轴承间隙不作及时调整,将导致轴齿轮轮齿折断,或减速机机体被破坏。     

自动扶梯齿轮断裂失效分析

某商场自动扶梯齿轮中部发生断裂,导致扶梯出现逆行故障。采用化学成分分析、硬度试验、金相检验、断口分析方法,对齿轮进行分析。结果表明：发生轮齿断裂的齿轮表面采用渗碳处理工艺,但淬硬层较薄,一旦淬硬层磨损,裸露出软的心部组织从而导致剃齿现象的发生;     

某减速机齿轮崩齿失效分析

某德国进口减速机齿轮使用时发生崩齿失效,本文利用宏观形貌、化学成分、金相组织、非金属夹杂、硬度及有效硬化层检测手段,对其断裂原因进行了分析。结果表明,该齿轮钢成分接近联邦德国国家标准(DIN)20Mn Cr5及中国国家标准(GB)20Cr Mn Ti,表层组织为高碳马氏体+少量残余奥氏体,心部组织为低碳马氏体;齿轮试样中存在氧化物、夹杂及孔洞;断口属于过载折断,主要是由于轮齿的应力超过其极限应力所导致。     

浅谈辊压机行星齿轮减速箱(器)润滑油的选择

减速器的设计、制造缺陷和辊压机系统的载荷异常是导致辊压机减速齿轮失效的重要原因,润滑不当是导致齿轮失效的另外一个重要原因。为了确保辊压机行星齿轮减速箱(器)润滑的科学性,在对齿轮失效机理研究的基础上,根据实践中取得的有得有失经验,主张选择这样的润滑油:粘度可以低一点,但箱(器)启动时一定要形成最佳的油膜保护;油品性能持久,降低齿面粗糙度(因为齿面粗糙度影响油膜的压力、膜厚和温度,从而影响润滑效果);油品清洁持久。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。