FFS重膜印刷机收卷部双锥度张力控制方法

目的解决FFS重包装膜在高速印刷过程中带卷过大所引起的卷膜中心处皱折和端面不齐等产品质量问题。方法提出一种双锥度张力控制方法,通过对收卷张力和辊筒压力分别采用锥度张力控制来有效控制卷膜内部张力的分布,令卷膜内部张力分布更加均匀。基于等效张力的概念,对卷膜中的单元体进行受力分析,得到卷膜受力和卷膜自身张力的变化规律。建立卷膜张力的数学模型,对双锥度控制方法的性能进行理论分析。结果通过集成到设计的平台上,对所提出方法的有效性进行验证,实验结果表明该方法使收卷张力更加稳定,可减少卷膜内层抓心变形,产品合格率提高至98%以上。结论实验结果验证了所提出方法和研制装置的有效性,可有效解决产品出现的质量问题。     

软包装复合膜收卷张力的优化

目的 为了改善软包装复合膜在生产过程中出现的复合皱折问题。方法 在现有薄膜收卷张力模型的基础上,对薄膜收卷的内张力进行分析,建立以卷径Ri=1.5R0为分界点的分段张力收卷模型。结果 按照该模型设置收卷张力可以很好地避免现有收卷张力模型存在的具有张力薄弱点和内部张力过大等问题,可以有效减小设备、材料等不稳定因素产生的影响,从而有效减少复合皱折问题。结论 利用这一优化的张力收卷模型,通过长期、大量的生产实践,统计出复合皱折损耗率从平均5%下降到低于1%,复合皱折问题得到明显的改善,给公司带来超过200万元/年的经济效益。     

布鲁克纳收卷机介绍及案例分析

介绍了布鲁克纳收卷机的组成和功能,以及10多年运行以来出现各类收卷故障的案例分析     

摩擦收卷中柔幅材料力学建模及张力控制策略研究

对柔幅材料在某新型高速摩擦收卷机收卷状态下力学行为进行研究,以张力为核心,将收卷状态下处于不同位段的幅材张力区分为工作张力和上卷张力两类,分别建立其力学模型,并提出对应的张力控制策略。为合理设计收卷机的结构,提高张力控制精度提供理论依据。     

卷筒料印刷装备收卷张力系统解耦控制研究

目的 为了保证卷筒料印刷装备收卷张力系统的性能,提出一种适用于收卷张力系统的自抗扰（ADRC）解耦控制器。方法 在收卷张力系统数学模型基础上,结合卷筒料收卷系统的工作原理,基于ADRC控制技术设计收卷张力系统的ADRC解耦控制器,并利用Simulink软件对所提出的控制策略进行仿真研究。结果 在相同的阶跃输入下,研究结果表明,PID控制器调整时间为2.4 s,而ADRC解耦控制器调整时间为0.7 s;在PID控制下,收卷基材张力出现超调和震荡,而在ADRC解耦控制下,基材张力无超调和震荡现象;采用PID控制器,收卷牵引跨度张力变化引起收卷跨度张力波动,而采用ADRC控制器则没有波动。结论 提出的卷筒料印刷装备收卷张力系统ADRC解耦控制器实现了高精度张力控制,具有比传统PID控制器更好的控制性能。     

缓冲包装的跌落冲击及其参数方程

对缓冲包装系统的跌落冲击过程的动态特性分三阶段进行了分析，以脆值理论作为基础，建立受跌落冲击的缓冲包装系统“无回跳”的参数方程。     

Estimation of the energy needs in life cycle analysis of one‐way and returnable glass packaging

The current position on the environmental advantages offered by returnable versus one‐way glass packages is discussed. The energy needs of both options are considered as important parameters. A critical concept in the published LCA studies is the breakage rate, which serves to estimate the number (n) of returns that a functional unit of bottles can perform. Normally the energy of production of the glass (E) is divided by n. The authors consider this concept too theoretical and for long‐term situations demonstrate that, in all LCA calculations, an energy value equal to 2E/n should be used. This value is useful in calculating the break‐even point. The paper summarizes the effect of different breakage rates and distribution distances on the break‐even point. It is clear that, for breakage rates below 5%, returnable glass bottles remain competitive and advantageous, even for quite long distribution distances. The methology proposed should be applicable to other materials. Copyright © 1999 John Wiley & Sons, Ltd.     

Mechanical and three-body abrasive wear behaviour of three-dimensional glass fabric reinforced vinyl ester composite

The mechanical and three-body abrasive wear behaviour of two- and three-dimensional E-glass woven fabric reinforced vinyl ester composites were studied in this article. The mechanical properties were evaluated using universal testing machine as per ASTM D-638. Three-body abrasive wear tests were conducted using rubber wheel abrasion tester (RWAT) under different abrading distances at two loads, wherein the wear volume loss were found to increase and that of specific wear rate decrease. The results indicate that the three-dimensional glass woven fabrics in vinyl ester (G_3D–V) have significant influence on wear under varied abrading distance/loads. Further, it was found that G_3D–V composite exhibited lower wear rate compared to two-dimensional glass woven fabric reinforced vinyl ester (G_2D–V) composite. The worn surface features, as examined through scanning electron microscope (SEM), show ruptured glass fiber in G_2D–V composite compared to G_3D–V composites.     

应变率和温度对耐碱玻璃纤维织物增强水泥基复合材料弯曲力学行为的影响

为研究不同应变率和温度下耐碱玻璃织物增强水泥基复合材料的弯曲力学行为,采用美特斯(MTS)万能试验机和INSTRON落锤冲击系统对其试样分别进行室温(25℃)下准静态三点弯曲(应变率为3.33×10-5 s-1)和不同应变率(4、8、12、16和18s-1)及温度(-50、0、25、50和100℃)下的动态三点弯曲试验,静态和动态三点弯曲试验采用一套弯曲夹具。同时考虑了增强织物层数对其弯曲力学性能的影响。试验结果表明:室温下,随应变率的增加,弯曲强度提高,弯曲峰值应变和韧性先减小后增大,弯曲模量先增大后减小;应变率为12s-1时,随着温度的升高,弯曲强度、弯曲模量和韧性整体上减小,弯曲峰值应变变化不明显;纤维织物为六层时,对混凝土的增韧效果较明显。应变率、温度和织物层数均能对试样的弯曲性能产生较大影响。     

紫外光分光光度法测定食品包装纸用天然色素虎杖黄酮含量的研究

研究了紫外光分光光度法测定食品包装纸用色素虎杖黄酮含量的方法,以芦丁为参照品,测量波长为359nm,平均回收率为99.96%,精密度为1.34%,说明紫外分光光度法是一种较理想的测定方法.     

Polyamide coated glass fabric in polyester resin: interlaminar shear strength versus moisture absorption studies

An experimental investigation was carried out to study the effect of polyamide coatings on the adhesion and moisture absorption behaviour of glass/polyester composites. Glass fabrics (chopped-strand mats) were coated with polyamide 6,6 by interfacial coating and solution dip-coating. Hand lay-up was employed to fabricate polyester-based laminates. Short beam shear tests were performed in order to assess the effect of the coating on the adhesion of the fibre to the matrix. The data show that both coatings have a negative effect on the interlaminar shear strength. Moisture absorption tests were also carried out. Weight gain data versus time of immersion were collected at different immersion temperatures and the water uptake at equilibrium (M_∞) and the diffusion coefficient (D) were calculated. An increase in M_∞ and D, as the amount of polyamide coating on the glass fibres increases, was observed. We also observed that many of the diffusion curves, at lower temperatures, exhibit a two-stage sorption (2SS) form.     

Hybrid effects in thin ply carbon/glass unidirectional laminates: Accurate experimental determination and prediction

Experimental results are presented which allow the hybrid effect to be evaluated accurately for thin ply carbon/epoxy–glass/epoxy interlayer hybrid composites. It is shown that there is an enhancement in strain at failure of up to 20% for very thin plies, but no significant effect for thicker plies. Hybrid specimens with thick carbon plies can therefore be used to measure the reference carbon/epoxy failure strain. The latter is significantly higher than the strain from all-carbon specimens in which there is an effect due to stress concentrations at the load introduction. Models are presented which illustrate the mechanisms responsible for the hybrid effect due to the constraint on failure at both the fibre and ply level. These results give a good understanding of how variability in the carbon fibre strengths can translate into hybrid effects in composite laminates.     

Effects of nano-sized and micro-sized carbon fibers on the interlaminar shear strength and tribological properties of high strength glass fabric/phenolic laminate in water environment

In order to clarify the effects of carbon fiber size on the properties of carbon fiber/high strength glass fabric (HSGF)/phenolic laminate, two kinds of laminates modified by nano-sized carbon fibers (CNFs) and micro-sized carbon fibers (CMFs), were respectively fabricated. The interlaminar shear strength (ILSS) and tribological properties of HSGF/phenolic laminates modified by CNFs and CMFs in water environment were comparatively investigated. Results showed that CNFs at proper contents ranging from 1.0% to 3.0% can enhance ILSS of HSGF/phenolic laminate, while CMFs deteriorated the ILSS. After water immersion, ILSS of the laminates modified by CNFs at 1.0–3.0% were just slightly decreased; however, those of the laminates modified by CMFs suffered larger drop. On the other hand, however, CMFs were more effective than CNFs in improving the wear resistance of HSGF/phenolic laminate in water.     

Evaluating J‐integral and Q parameter in high‐density polyethylene using a combined experimental finite element method

This work introduces a combined experimental finite element method (FEM) to calculate J‐integral and Q parameter for centre‐crack tension of high‐density polyethylene specimens. In the majority of the studies to date, mostly a pure FEM has been used. However, the several simplified assumptions that are included in such models could result in imperfect predictions. This study aims to overcome this issue by suggesting a novel method that privileges from the displacement fields on specimens' surface that is provided for our finite element model. The method introduced in this work has a merit in presenting Q results for a softening material. The results of our proposed method were in a satisfactory agreement with the pure FEM results of similar models, and thereby validating our approach. Using this model, the effects of parameters like crack length and thickness were also investigated. This method could be utilized in health monitoring of structures.     

轿车后围板成形过程数值模拟及参数优化

为提高轿车后围板零件的成形质量和设计效率,采用单向拉伸试验,测定了板料的力学性能参数,并对测量参数的有效性进行了验证;基于测量的参数,对该零件的冲压成形过程进行了数值模拟,改进了拉延筋的受力并优化了工艺和模具参数;对零件成形之后的回弹进行了研究,并对回弹变形进行了补偿.研究结果表明:采用测定的参数能有效地提高数值模拟的精度;优化拉延筋的受力及成形参数,可以提高成形件的质量;利用补偿法可以有效的补偿零件的回弹变形;经验知识与数值模拟相结合的优化方法是提高产品质量及工艺设计效率的有效途径.