LWS400卧螺离心机参数变化对转鼓强度和刚度的影响

采用Solid Works软件建立LWS400卧螺离心机转鼓几何模型并导入ANSYS Workbench软件中进行有限元分析。分别改变转鼓转速、转鼓壁厚和液池深度三个参数并讨论由此对转鼓强度和刚度的影响,以便为后续的优化设计方案提供参考。讨论结果表明:转鼓转速的提高或壁厚的减小都对转鼓强度和刚度有明显的影响,液池深度的变化对转鼓强度和刚度的影响不大。     

气辅成型过程气体穿透行为与工艺参数优化的试验研究

基于带平板的回形管式气体辅助成型样件对气体穿透行为和残余壁厚与气辅工艺参数的关系进行了研究分析.试验结果表明,气辅工艺参数如气体延迟时间、气体注射压力和熔体预注射量是影响气体辅助成型中气体穿透长度和残余壁厚的重要因素,而各参数间的交互作用致使气体穿透与残余壁厚的变化趋势更为复杂.     

离心机开孔转鼓的强度分析

指出了现行开孔转鼓最大环向应力和壁厚许算公式中的不妥之处,并按薄壁结构对开孔圆筒形和圆锥形转鼓的强度进行了分析,导出了它们的最大环向应力和壁厚计算表达式。     

非均匀沉降下高压天然气管道失效概率分析

为了研究非均匀状态下高压天然气管道的失效概率,通过建立管道失效概率模型,根据可靠性理论与管道有限元分析得出了管道失效概率随沉降发展的变化曲线,并对管道失效概率的4种影响因素的敏感性进行了分析。结果表明:4种影响因素敏感性大小依次为管径、内压、壁厚、埋深。随着沉降的发展,管径、内压敏感性逐渐降低,埋深敏感性增强;影响因素的变化量增大时,壁厚敏感性逐渐降低。     

PET注拉吹制品壁厚分布的研究

通过注射拉伸吹塑实验分析了二次吹胀压力、拉伸杆速度以及吹胀延迟时间对瓶子轴向壁厚分布的影响。实验结果表明：吹胀压力的改变对瓶子轴向壁厚分布影响不大，拉伸杆速度与吹胀延迟时间的变化对瓶子轴向壁厚分布有显著影响。吹胀延迟时间的改变会形成不同的型坯轮廓发展模式，在注拉吹可视化实验结果的基础上，结合应力和温度场两方面的因素解释了型坯轮廓发展模式的成因。     

瓶坯尺寸对拉伸吹塑成型PET瓶壁厚分布的影响

通过对多个瓶坯的拉吹成型过程进行模拟分析,预测出不同尺寸的瓶坯所成型的PET瓶壁厚分布,并分析比较瓶坯尺寸对制品壁厚分布的影响。结果表明,瓶坯尺寸对于拉吹成型PET瓶的壁厚均匀性有较大影响,其中瓶坯局部厚度及瓶坯高度是主要影响因素。瓶坯整体壁厚对PET瓶轴向壁厚分布影响较小。PET瓶(不考虑体积时)最优瓶坯高度受瓶坯壁厚影响不大,采用有限元建模(FEM)仿真试验进行模拟分析可得到瓶坯最优高度取值范围。通过模拟计算和对瓶坯进行优化设计,可显著提高吹塑成型PET瓶的壁厚均匀性,且有助于PET瓶轻量化设计。     

天然气管道壁厚选择澳标和国标对比

对比分析了澳大利亚和我国天然气长输管道壁厚选择遵照的AS标准和GB标准,总结了二者在地区等级划分、设计系数选择、壁厚计算考虑因素、壁厚计算过程等方面的差异。AS标准中地区等级划分和设计系数没有一一对应关系,GB标准中不同地区等级对应不同设计系数,地区等级是管道壁厚选择的重要影响因素。AS标准中壁厚选择是基于风险的设计方法,考虑的影响因素全面,GB标准中是基于规定的设计方法,操作性强。另外,详细介绍了AS标准和GB标准中壁厚选择的步骤和方法。     

纤维缠绕压力容器封头壁厚预测方法分析

为建立准确纤维缠绕压力容器结构模型,在前人壁厚预测方法基础上采用多项式逼近算法来预测压力容器封头纤维层厚度。针对封头部分纤维缠绕角不断变化和极孔附近纱线堆叠等影响因素,采用多项式逼近算法进行封头壁厚预测,并与经典算法、精确算法、平面算法壁厚预测值及实际壁厚测量值对比分析,结果表明运用此方法得到的纤维层壁厚预测值与实际壁厚测量值更接近,从而为分析压力容器可靠性提供准确压力容器结构模型。     

基于响应面法的水辅助共注塑管件的工艺参数优化

以最小总壁厚及内层壁厚为目标,基于响应面法（RSM）对成型工艺参数进行优化。由单因素实验确定总壁厚和内层熔体壁厚的主要影响因素;由Plackett Burman试验确定关键因素;再通过Box Behnken试验设计和响应面法分析与优化,获得最小总壁厚和内层熔体壁厚的工艺条件为：注水压力7.5 MPa,注水延迟时间2s,内层熔体温度215℃;在优化条件下,利用Design-expert模型预测总壁厚和内层壁厚与实验结果吻合较好,表明响应面法能够优化水辅助共注塑管件最小壁厚的工艺参数。     

短玻纤聚丙烯水辅注塑中注水压力控制方式的数值模拟

基于广义非牛顿本构方程,采用有限体积法对不同注水压力控制方式下短玻纤聚丙烯水辅注射成型进行数值模拟。研究表明,注水压力控制方式的改变,会对水辅注塑制件的残余壁厚、偏心率产生一定的影响;使用折线式的控制方式,不同分组之间残余壁厚大小相近,偏心率均较大,同一分组下残余壁厚的变化较小;使用阶跃式的控制方式,不同分组下残余壁厚大小都不相近,且偏心率较小,同一分组下残余壁厚的变化较大。     

影响挤出吹塑制品质量的成型工艺分析

在实验的基础上，探讨了成型工艺对挤出吹塑制品质量的影响。制品壁厚分布情况和制品重量是制品质量衡量标准中最重要的两个方面。熔体温度和螺杆转速对型坯成型中型坯的膨胀和垂伸产生影响进而影响制品壁厚分布和制品重量，而吹胀压力对制品壁厚分布有一定影响，但不会影响制品最终重量；其变化不会导致制品壁厚整体的增大或减小。研究得到的结论在实际生产中有助于确定最优成型工艺条件。     

中空吹塑成型机壁厚控制系统的发展

叙述中空吹塑成型机壁厚控制系统及中空吹塑成型机的发展状况,重点对其壁厚控制器的发展进行介绍,并通过对国内外壁厚控制器现状的比较,归纳出壁厚控制器的发展趋势,最后提出我国壁厚控制系统的发展对策。     

口模异型化设计在优化挤出吹塑中空工业制件壁厚分布中的研究与应用

以典型中空工业制件为研究对象,详细分析了影响挤出吹塑成型制件壁厚分布的主要因素,针对性地提出了口模异型化设计方案,并通过多次试模分析和修改设计方案,加工出合理的异型口模,较大地提高了制件壁厚分布的均匀性,提出了一种优化挤出吹塑成型中空工业制件壁厚分布的有效措施.     

结晶型工程塑料的收缩与模具设计

以聚酯PBT为例阐述了结晶型工程塑料的成型收缩率与制品壁厚、注射压力、保压压力、注射时间、保压时间、模具温度、冷却时间、模具设计等的关系。玻璃纤维增强PBT的成型收缩率还与玻璃纤维的定向排列有明显关系。此外还介绍了成型收缩率的评价方法。     

基于传递矩阵法的干气密封试验台转子固有频率计算

利用传递矩阵法对干气密封试验台转子系统进行了简化,并分段建模。对其典型单元的状态进行了数学描述,针对干气密封试验台转子自身的结构数据,在Maple中进行编程求解,获得了转子的一阶固有频率。同时基于干气密封试验台测试系统的LabView平台测试和分析,得到了干气密封试验台转子的一阶固有频率与传递矩阵法的计算结果基本吻合。这表明:用传递矩阵法计算干气密封试验台转子的固有频率是可行的,而且很接近实际情况,对今后实际工况下的干气密封系统转子的动力学分析具有重要的参考价值。     

Study on the residual wall thickness at dimensional transitions and curved sections in gas‐assisted molded circular tubes

Plastic tubes and hollow rods can be fabricated using gas‐assisted injection molding technology with reduced cost. The residual wall thickness around dimensional transitions and curved sections is of great concern. This research investigated the uniformity of the residual wall thickness distribution in circular tubes with dimensional variations and curved sections. It was found that the wall thickness was not uniform near transitions. With the addition of fillets with proper angles around transitions, the uniformity of residual wall could be greatly improved. The residual wall thickness in curved sections was thick around the outer wall and thin around the inner wall. Low melt temperature and high gas pressure were found to reduce the deviation in the wall thickness around curved sections.     

Motion control for uniaxial rotational molding

Motion control parameters of rotational molding can affect process efficiency and product quality. Different motion control schemes will lead to varied powder flow regimes exhibiting different levels of mixing and temperature uniformity. The change in nature of powder flow during a molding cycle suggests that varying the rotational speed could improve the powder mixing and temperature uniformity, therefore potentially reducing processing time and energy consumption. Experiments completed investigating powder flow under uniaxial rotation show that savings of up to 2.5% of the heating cycle time can be achieved. This validates the hypothesis that altering the rotational speed to maintain the ideal powder flow throughout the heating cycle can be utilized to reduce the time taken for all the polymer powder to adhere to the mold wall. The effect of rotational speed on wall thickness uniformity and impact strength were investigated and discussed. Results show a strong influence of rotational speed (and powder flow) on the wall thickness uniformity of the moldings with wall thickness uniformity deviations of up to 50% found (within the 2–35 RPM speed range tested).     

Variation of Part Wall Thicknesses to Reduce Warpage of Injection-Molded Part: Robust Design Against Process Variability

This article introduces a concept for deliberately varying the wall thicknesses of an injection-molded part within prescribed dimensional tolerance to reduce part warpage. The “warpage” described is measured from warpage simulation so as to represent various deformation behaviors of the molded part. Considering the variation in molding process as noise factors, a wall thickness model that minimizes the effect of these noises on warpage characteristics is obtained using the Taguchi method. The warpage characteristics of this model are compared with those of the constant-wall-thickness models that comply the general rule of an uniform wall thickness in part design. Each wall thickness model is then simulated for plausibly small process fluctuations against the best process conditions of each model that would occur in the actual molding operation. It is seen that varying wall thicknesses obtained by the present study exhibits better warpage characteristics in terms of warpage mean and variance against this mean, compared to the constant wall thicknesses.     

水驱动弹丸辅助注塑管件壁厚的弹丸影响

对水驱动弹丸辅助注塑(W-PAIM)中弹丸对管件壁厚的影响进行了实验与分析.通过搭建实验平台研究了弹丸的材质、头部形状、直段长度、截面尺寸这4个因素对聚丙烯(PP)的W-PAIM管件残余壁厚的影响.结果表明,在聚酰胺6(PA6)、丙烯腈-丁二烯-苯乙烯共聚物(ABS)、聚四氟乙烯(PTFE)、PP 4种弹丸材质中PA6...     

Orientation development in molding of short-fiber liquid crystalline polymer composites

The orientation development mechanisms that take place during molding of short-fiber reinforced liquid crystalline polymer composites, have been analyzed and consequently the orientation development and properties distribution were studied for the case of thin wall large area components. Two factors associated with orientation development were investigated. The first is related to the melt front shape for in-plane orientation distribution, and the second to the thickness of the skin layer where the alignment of the orientable liquid crystalline matrix and the rigid reinforcing fibers are of importance. The two basic factors were first verified by flow calculations using a computer assisted design (CAD) system and then experimentally validated. Experimental results for thin wall large area plaques have shown that the control over the melt front shape could be achieved with a narrow restrictor-type gate and that the skin layer thickness is determined by the heat transfer processes during filling of the mold. Furthermore, a clear correlation has been established between the measured tensile properties and the ratio of skin layer to total thickness of the plaque. Such correlations should be generally developed for short-fiber polymer composites for cases where rigidity and load bearing capabilities are of importance.