基于PLC的塑料挤出机控制系统设计

为了保证塑料挤出机的稳定可靠运行,提高塑料挤出机的智能自动化程度,设计了一套基于可编程控制器(PLC)的塑料挤出机控制系统。介绍了塑料挤出机工作原理,设计了控制系统硬件系统,通过触摸屏实现了挤出机参数设置、数据显示、数据曲线采集,由PLC实现执行机构的控制。在硬件结构基础上设计了PLC软件主要流程,并设计了触摸屏画面。该控制系统能够实现挤出机温度和压力等工艺参数的精确控制,保证了塑料挤出机稳定可靠运行。     

销钉式冷喂料挤出机供胶系统在轮胎钢丝帘布压延中的应用

介绍销钉式冷喂料挤出机在钢丝帘布压延中的应用。Φ200 mm销钉式冷喂料挤出机主要由机头、机筒、喂料段、螺杆、主机减速箱、润滑系统、温度控制系统和电气控制系统组成。当螺杆转速在15~25 r·min-1时,螺杆转速与排胶量线性关系较好。与开炼机供胶系统相比,销钉式冷喂料挤出机供胶系统供给的胶料门尼粘度降幅明显减小,炭黑分散性能较好。用销钉式冷喂料挤出机供胶系统代替开炼机供胶系统,钢丝帘布胶加工性能和物理性能大幅提升,生产能耗和制造成本降低。     

塑料挤出机加热冷却系统节能的研究进展北大核心

综述了塑料挤出机加热冷却系统的节能研究进展。塑料挤出机的节能可通过挤出系统、传动系统和加热冷却系统的节能来实现。为精确控制温度,生产过程中需不断加热和冷却。介绍了冷却系统的改进及在提高产品质量和挤出机对原料的适应范围等方面的改进。加热冷却系统改造后,系统耗电量大幅下降,节能率超过20%。     

基于PLC的塑料挤出机温度控制系统设计

塑料挤出机料筒温度控制系统存在扰动大、时变、滞后以及非线性等特点,使得料筒温度升温慢、控制精度低、抗干扰能力差,传统PID控制依赖精确数学模型,无法实现参数的在线实时调整。本文设计了一种模糊PID的塑料螺杆挤出机温度控制系统和以松下PLC为控制核心的挤出机温度控制系统硬件结构,最后对该控制方法进行了仿真分析。结果表明:该控制系统具有良好的动静态特性,在一定程度上改善了传统PID控制超调量大、温度变动大等缺点。     

塑料挤出机加热冷却系统节能的研究进展

综述了塑料挤出机加热冷却系统的节能研究进展。塑料挤出机的节能可通过挤出系统、传动系统和加热冷却系统的节能来实现。为精确控制温度,生产过程中需不断加热和冷却。介绍了冷却系统的改进及在提高产品质量和挤出机对原料的适应范围等方面的改进。加热冷却系统改造后,系统耗电量大幅下降,节能率超过20%。     

挤出温度对开孔型橡塑多孔材料性能的影响

研究了挤出温度对开孔型橡塑多孔材料性能的影响。结果显示：挤出机均化段温度和机头温度是影响多孔材料性能的关键因素；多孔材料的拉仲强度及断裂仲长率随挤出机均化段温度的变化曲线均显现出极小值；多孔材料的拉仲强度和断裂伸长率随挤出机机头温度的升高呈现降低趋势；而其弹性模量随挤出机机头温度变化曲线存在极大值。     

塑料挤出机温度的模糊PID控制

设计了一种基于可编程控制器(PLC)和触摸屏相结合的塑料挤出机温度智能控制系统。介绍了塑料的温度特性,在此基础上设计了以PLC为控制核心的硬件系统,采用热电偶传感器采集温度信号并经过变送器将信号传送到控制器中,采用模糊比例积分微分控制算法实现温度控制的闭环自适应控制。结果表明:设计的温度控制系统可将温度误差控制在±1.5℃以内;该控制系统可以有效地提高系统温度控制精度,对于提高塑料制品质量具有重要作用。     

转矩流变仪RC90系统的技术与应用

介绍了转矩流变仪的发展、基本原理和应用。各种混合器、单螺杆挤出机、双螺杆挤出机、模具和后挤出机系统都能与RC90装配。RC90可用于对材料的熔融性能和热稳定性、颜料分散性、交联、固化和硫化性能以及挤出可加工性能等的研究。     

橡胶挤出机的发展状况（上）

文章介绍了国外橡胶挤出机的发展状况，其中包括冷喂料挤出机、销钉机筒冷喂料挤出机、排气式冷喂料挤出机、传递式挤出机和销钉传递式挤出机。本文就上述挤出机及挤出机头的结构、技术参数和优异性能作了简要介绍，同时指出温度控制和过程控制的发展情况。     

行星齿轮辊筒挤出机模型设计

描述了近几年一直被研讨的加工过程中的挤出机性能的模型建造方法,及机械应用设计。目前建模方法已经发展为行星齿轮辊筒挤出机,这种挤出机可以给出输送特性、温度、功率消耗和停留时间分配。     

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.     

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.     

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。     

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.     

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。