波状注塑螺杆熔体输送机理的研究

本文在综合分析国内外波状螺杆研究成果的基础下,根据注射机预塑过程的特点,建立了更真实地反映波状螺杆工作机理的三维理论模型。在模型中将背压做为一个重要变量予以考虑,采用分段的二维有限元与差分迭代相结合的方法,对等温幂律流动的速度场,压力场和应力场进行了求解,在计算的基础上又进一步分析了波状螺杆几何参数、预塑工艺条件和物料流变参数对熔体输送总流率、压力降、槽向压力分布及扭矩和能耗的影响。对部分计算结果在注塑机实验台上进行的实验验证表明:采用本文理论模型的计算结果与实验结果相近,说明本文的理论模型和计算方法具有一定的工程实用性。     

基于Pro/E注射机螺杆的参数化建模

以塑料注射机螺杆为例,介绍用Pro/E作为工具进行参数化设计的方法,详细介绍了采用Pro/E工具中的关系和参数命令对注塑机3种类型螺杆进行参数化建模的方法和不变参数的设定.利用参数界面改变参数可以自动生成螺杆的三维模型.通过进一步举例说明这一方法可以在已设定好参数的情况下建成不同规格注射螺杆,为螺杆设计节省时间.     

螺杆参数对注射机塑化单产能耗影响的模拟分析

对注塑螺杆计量段槽深h3、长度L3,、螺距S和螺杆与机筒内壁间隙δ四个因素建立正交试验表,通过著名的流体有限元分析软件Polyflow分析了它们对注射机塑化能耗的影响,给出了对塑化单产能耗影响因素的大小顺序,为设计节能型螺杆提供了依据.     

注射机螺杆断裂失效分析

采用金相分析、硬度检测等方法,对断裂的注射机螺杆进行了失效分析。结果表明:基体材质不良和热处理不当是导致螺杆断裂的主要原因。     

各种特种螺杆概述

为克服普通螺杆存在的固有缺点,近30年来开发了许多特种螺杆,目前已达到一定的高度。本文概述了五类特种螺秆:1.分离型螺杆,包括M、DFM、B、HCB、LHW、DL、K及IH等螺杆;2.混炼型螺杆,包括分散式及分流式两种混炼元件;3.螺杆套螺秆的双螺杆型,包括XLK及SDS螺秆;4.压缩—减压型螺杆,包括波状及ET螺杆;5.其他类螺杆,包括HM、SX、Dray及带波型泵的螺杆。     

新型波状注塑螺杆的特性

挤出与注塑是塑料成型加工中应用最广的两类成型工艺,螺杆是其关键部件,因而对螺杆结构的研究是至关重要的。就单螺杆而言,目前已有各式各样的螺杆,近年来国外在原有的分离型、混炼型螺杆的基础上,又开发出螺杆套螺杆的双螺杆型,压缩—减压型的单螺杆。压缩—减压型螺杆又有能量传递式(ET)螺杆和波状螺杆。波状螺杆与普通单螺杆一样,仍分固体     

热固性增强塑料注射成型机的螺杆结构参数

115厂和西北工业大学等单位在共同研究改性酚醛玻璃纤维增强塑料注射成型时,在GZH—200克注射机上研究并选择了螺杆结构参数,取得了初步成果。 螺杆是塑料注射机的关键部件。螺杆结     

注射螺杆的可靠性设计

根据注射螺杆在塑化时的受力情况,应用可靠性设计原理介绍了注射螺杆疲劳强度的可靠度的计算方法,并以实例说明.对注射成型机的设计有一定的应用价值.     

排气式注射机的设计与开发

阐述了排气式注射机的工作原理及其设计,介绍了排气注射螺杆的设计特点,排气口的结构设计要求,对真空排气系统进行了简要介绍。利用正交实验的方法分析了操作参数排气效果的影响程度,用以指导排气式注射机的设计和操作。     

PVC专用注射螺杆的结构设计及参数优化

在设定了PVC专用注射螺杆的结构参数及范围后,进而采用正交试验法在Adina流体分析模块中进行了计量段塑化过程的模拟分析,通过观察熔体在计量段的压力场、剪切应力场和速度场,优选了计量段参数,并最终设计了PVC专用注射螺杆;最后对所设计的螺杆进行了三维建模。     

超大型螺杆压缩机转子铣刀的设计和制造

目前国际上螺杆压缩机转子最大直径达函816mm,制造这种超大型阴阳螺杆转子需要特殊的大型刀具。根据研究分析和实际生产运用,对超大型阴阳螺杆转子刀具铣刀型线的设计、刀体结构、刀片材料、切削用量等进行了阐述,并提出了解决问题方法,同时重点分析了整体刀具结构的优点。用该套刀具加工的Φ816mm转子的啮合精度,表面粗糙度,均达到设计要求。     

Effect of screw design on fiber damage in extrusion compounding and composite properties

The mechanism of fiber length degradation during twin screw extrusion compounding and methods to reduce it through process and machine design are extremely important in discontinuous fiber reinforced composites. Fiber damage along the screw and the extruder die are determined for three screw designs with different mixing sections. The pellet quality, wet-out, and fiber dispersion in the extruded strands are compared. The fiber orientation distributions in the screw are determined to identify regions of higher fiber interaction. The fiber damage during subsequent injection molding has also been determined. The tensile, flexural, and impact properties of the tensile bars are compared. It is found that the residence time, fill-up, and the intesity of mixing during extrusion compounding have a predominant effect on fiber length degradation. The screw designs were seen to have a greater effect on the fiber damage in the 40 wt% glass-filled polymer than the 30 wt% glass-filled polymer. However, the mechanical properties of the 30 wt% glass-filled polymer showed an increasing trend compared to the 40 wt% glass filled polymer. A screw design that provides a balance of the fiber length, wet-out, and fiber dispersion was noted to give consistent mechanical properties.     

Computer-aided optimal melt screw design

The paper describes a computer software package applying a steady-state hill-climbing optimization routine to the plastics melt-extruder screw constrained-design problem. The purpose primarily is to introduce the optimal screw-design technique, to show how it is applied to this particular type of problem, to indicate its potential and to encourage its wider use. Screw performance criteria are defined by a theoretical model consisting of the non-Newtonian isothermal polymer flow equations in terms of the screw-geometric variables for particular process conditions. The design method is quite general however and a non-isothermal model may be substituted. Use of the method offers considerable scope and potential for the design engineer to make design processes faster, more positive and logical while reducing the effort required. Interactive use is possible and empirical adjustments can be incorporated with experience. In using the method, the design engineer first specifies the required process conditions of pressure and flow rate at the die and the computer then searches for the set of screw design variables which optimizes the screw power utilization efficiency or any other specified criterion of performance. Such optimal designs are obtained within the set limits of practical constraints on machine dimensions, screw strength and product quality requirements. Some experimental evidence is given relating to the accuracy of the isothermal non-Newtonian polymer flow model and to its use in the design of small diameter extruder screws. The optimal search technique offers considerable potential as a computer-based design tool.     

A melting model for reciprocating screw injection-molding machines

A theoretical model for melting in reciprocating screw injection molding machines is proposed. The model permits the calculation of the solid bed profile as a function of time during the injection cycle. It consists of a dynamic extrusion melting model for the rotation period, a transient heat conduction model with a phase transition for the screw rest period, and a proposed model for the drifting of the beginning of melting during the injection cycle.     

Effect of screw design on hopper drawdown of spherical particles in a horizontal screw feeder

Screw feeders are used to remove material from hoppers and bins at a controlled rate. The evenness of the flow in the bin depends on the drawdown pattern, which in turn depends on the screw and hopper design, shape of the particles and wall friction effects. A key design requirement is to ensure that a progressive increase in the screws volumetric capacity is achieved along the entire length of the hopper's opening so as to produce even drawdown. If this is not achieved then compositional variations in the outgoing stream and other operational problems (such as caking) can be created. Screw designs to date have been generally based on analytical models and at times the predicted flow pattern is not achieved. In this study, the Discrete Element Method (DEM) is used to predict particle transport in a horizontal screw feeder system for a range of conventional screw designs including a variable screw pitch, variable screw flight outside diameters and variable core diameters. The influence of screw choice on the particle mass flow rate, the evenness of particle drawdown from the hopper, power consumption, screw wear and wall friction variations are all investigated. Important features captured by DEM that are not accounted for by the analytic model and which vary strongly between competing screw designs, include the particle circulation in the hopper, shearing of the particle bed in the trough just outside the screw and the spatially varying particle force along the hopper which leads to non-uniform drawdown and to the existence of large stagnant or slow moving zones. The screw design and consequent flow patterns also strongly affect the power draw with variations up to a factor of three and screw wear with large changes in their distribution and magnitude. Finally, the surface frictional properties of the screw are shown to strongly influence the rate of bed compaction within and along the screw leading to strong variation in mass flow rate, uniformity of drawdown and power draw.     

低剪切螺杆挤出性能的研究

通过对普通螺杆和低剪切螺杆不同的机头压力和螺杆转速下的对比试验得出，在胶料粘度较低时，螺杆转速和胶料种类是影响低剪切螺杆挤出功率的重要因素。在同一条件下，低剪切螺杆的挤出温度高于普通螺杆，机头压力低于普通螺杆，从而进一步了解低剪切螺杆的塑化和混合性能，为螺杆的设计参数的确定提供了依据。     

注塑螺杆的塑化质量实验研究

螺杆是注塑机注射装置的核心部件,和塑料直接接触,对物料在料筒中塑化过程起着最直接的影响,其结构及性能的优劣最终直接影响着整台机器的效率及制品性能的好坏。本文在实验的前提下,通过对比分析不同螺杆参数对制品的影响,从制品重量重复精度、力学性能和塑化效率方面在定性的理论上做出定量分析。     

热塑性弹性体的挤出和螺杆设计

概述了热塑性弹性体的挤出加工条件和挤出螺杆的设计要求,并通过分析比较指出,对于某一类热塑性能体的挤出加工来说,即便其组成材料相同而中是组分比例有差异,也很难从整体上给出统一的加工条件和螺杆设计的特定规则。     

挤出机螺杆熔融段的优化设计

讨论了挤出机螺杆熔融段的优化设计问题。以单位产量能耗最小为优化目标 ,建立简化的挤出机熔融段螺杆优化设计的数学模型 ,应用复合形法求解。结果表明 ,计算所得熔融段起、末端的螺槽深度、螺纹顶宽度和螺纹升角均位于或接近文献中所建议的最佳取值范围     

通用型螺杆与分离型螺杆对注射用PVC-U复合粉料塑化效果的比较

对比了通用型螺杆与分离型螺杆对PVC-U复合粉料的塑化效果,分析了其结构形式及工作原理,发现分离型螺杆适用于PVC-U复合粉料的加工。