细长型塑料件翘曲控制成型工艺优化与应用

以典型细长型塑料件微波炉拉手为研究对象,建立塑料件CAE分析模型,采用多因素正交实验方法,对塑料件的注塑成型过程进行仿真有限元分析,获取了不同工艺参数下的翘曲变形量,采用基于Minitab的极差分析方法分析了正交实验中各因子对翘曲变形量的影响,确定了塑料件翘曲变形控制的最佳成型工艺方案。通过仿真模拟实验及试模注塑验证表明:优化后的翘曲控制成型工艺方案可以有效地降低塑料件的翘曲变形,解决了企业微波炉拉手翘曲变形缺陷的问题。     

“角落效应”对塑料件翘曲变形的影响

由于注射成型塑料件时有内应力,所以翘曲变形不可避免。找出导致变形的原因是改善塑料件变形的首要问题。采用Moldflow对汽车零件翘曲变形进行分析,快速确认引起翘曲变形的主要原因是"角落效应",将该塑料件转角料厚由4 mm改为2 mm,最终变形量由原始的2.9 mm变为0.6 mm,减少了80%。     

基于斐波那契法的注射保压优化及脱模设计

传统单一恒定保压效果不佳,易导致塑料件产生较大翘曲变形,以汽车饰条为例,采用斐波那契迭代优化算法结合模流分析,对注射成型过程进行分段保压设计,通过8次迭代演算与数值模拟,获取了最优的保压压降组合,得到最小的翘曲变形量,比恒定保压塑料件翘曲量减少了37.55%,有效地控制了塑料件的翘曲量。实践证明该方案可靠有效。     

超高速注射下塑料熔体流动性能研究

以高音喇叭薄膜为研究对象,利用Moldfl ow 2012软件对塑料件进行填充、冷却、翘曲分析,比较了普通注射成型和超高速注射成型下模具型腔的充填以及注塑件翘曲变形的结果。结果表明,相比于普通注射成型,超高速注射成型下熔体等值线均匀,流动平稳,熔接痕少,塑料件的成型质量好;普通注射成型塑料件的翘曲量为4.203 6 mm,超高速注射成型塑料件的翘曲量仅为0.111 6 mm。模拟试验结果证明,对于薄壁制品,超高速注射成型比普通注射成型更合适。     

汽车B柱窗框塑料件RHCM注塑翘曲变形分析及工艺优化

通过对汽车B柱的窗框塑料件快速热循环注塑成型(RHCM)过程及其工艺方案的研究，将翘曲变形量作为优化目标，运用Taguchi试验法设计了5因素4水平工艺组合方案，采用Moldflow软件进行模拟仿真工艺优化。将16组翘曲变形结果进行极差和方差分析，结果表明，RHCM下蒸汽温度对窗框塑料件翘曲影响最为显著，其最佳工艺方案为蒸汽温度145℃、保压压力90 MPa、加热时间20.7 s、保压时间26 s、冷却时间24 s。该工艺组合方案下翘曲变形量为1.583 mm，较优化前降低了56.5%。通过分离翘曲原因，塑料件的变形主要是由Z方向上的收缩不均引起的。将优化结果与传统注塑(TIM)相比，分析表明RHCM工艺在注塑过程中对模具温度进行动态控制，使得塑料件内部收缩率分布更加均匀，翘曲变形量更小，可显著提高塑料件成型质量。     

基于CAE的PP塑料件注射成型工艺参数的影响及优化

利用Moldflow软件对某建筑用塑料件的注射成型过程进行了模拟分析,首先研究了单个实验因素对塑料件翘曲量的影响,然后根据实验结果采用正交设计实验方法对注射成型工艺参数进行了优化。结果表明,在选取的注射成型工艺参数中,其中模具温度、熔体温度、保压压力和注射时间对翘曲量影响较大,适当增加模具温度、熔体温度和保压压力可有效减小翘曲量,注射时间对翘曲量的影响比较复杂,翘曲量随注射时间的延长先减小后增加;根据各工艺参数对翘曲量的影响规律,确定各工艺参数水平,优化后的成型工艺参数改善塑料件质量,有效地减小了塑料件翘曲量。     

基于正交试验法的加湿器底座注塑工艺优化设计

以加湿器底座为例,结合正交试验法和模流分析软件Moldfl ow,对不同注塑工艺条件下的底座零件成型过程进行分析,确定塑料件的翘曲量为塑料件表面质量的评价指标。通过对塑料件的翘曲量的极差分析,确定了模具温度、熔体温度、填充时间、保压方式和保压压力等工艺参数对塑料件翘曲量的影响程度的大小,绘制了水平影响趋势图,分析得出最优的注塑工艺参数配置,并对该工艺参数配置进行了模拟对比分析。     

汽车塑料件翘曲变形CAE模拟分析

以汽车塑料件为例,研究其注射成型翘曲的部位及成因.基于数理统计理论,结合正交实验设计方法,采用CAE软件对塑料件进行翘曲和体积收缩率的分析,得出各个因素水平的最佳组合,以使塑料件翘曲变形达到最小,从而提高塑料件质量.     

注塑成型工艺对汽车座椅塑料件力学性能的影响

以汽车座椅塑料件为例,以有限元软件Moldflow与Abaqus为技术平台,模拟分析汽车座椅塑料件的注塑成型过程与汽车座椅塑料件在实际工况下的应力分布。利用Moldflow软件模拟,得到汽车座椅塑料件在成型后的翘曲变形和残留的应力场。再将塑件的残余应力场作为预定义应力场导入到Abaqus软件中,在此基础上施加实际的边界条件与载荷,并与无预定义应力场塑件上加载进行对比,研究注塑成型工艺对塑料件力学性能的影响。结果发现,随着模具温度、熔体温度的降低与保压压力的增大,汽车座椅塑料件在服役状态下的应力增大。该研究结果对提高注塑件的结构分析精度将有较大的现实意义。     

薄壳多孔塑料件高光注射成型工艺研究

对手机壳体塑料件进行了常规注射成型CAE研究,分析存在较为严重的表观质量问题。通过采用高光成型技术,以沉降指数、体积收缩率和翘曲变形为质量指标,利用正交试验和多目标综合平衡法分析研究得出该产品的最佳成型工艺参数组合。分析结果表明,高光注射成型技术在改善薄壳多孔塑料件缺陷方面比常规注射成型有着更大的优越性。     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009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、环氧树脂、不饱和聚酯树脂)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。     

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.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。     

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.     

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.