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。     

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%。     

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。     

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。     

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。     

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.     

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.     

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。     

Inorganic/organic nanocomposite coatings: The next step in coating performance

Inorganic/organic hybrid materials have considerable promise and are beginning to become a major area of research for many coating usages, including abrasion and corrosion resistance. Our primary approach is to prepare the inorganic phase in situ within the film formation process of the organic phase. The inorganic phase is introduced via sol-gel chemistry into a thermosetting organic phase. By this method, the size, periodicity, spatial positioning, and density of the inorganic phase can be controlled. An important aspect of the inorganic/organic hybrid materials is the coupling agent. The initial task of the coupling agent is to provide uniform mixing of the oligomeric organic phase with the sol-gel precursors, which are otherwise immiscible. UV-curable inorganic/organic hybrid systems have the advantages of a rapid cure and the ability to be used on heat sensitive substrates such as molded plastics. Also, it is possible to have better control of the growth of the inorganic phase using UV curing. It is our ultimate goal to completely separate the curing of inorganic and organic phases to gain complete control over the morphology, and hence optimization of “all” the coating properties. Thus far, it has been found that concomitant UV curing of the inorganic and organic phases using titanium sol-gel precursors afforded nanocomposite coatings which completely block the substrate from UV light while maintaining a transparent to visible light. Also, it has been found that the morphology of the inorganic phase is highly dependent on the concentration and reactivity of the coupling agent. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004, in Chicago, IL.