注塑螺杆计量段槽深和导程的模拟及优化

首先建立注塑螺杆的模拟及优化平台,该平台以Injection Molding Plastification(IMP)软件为基础,结合DOE(实验设计)方法,将不同螺杆的模拟结果进行DOE分析和优化。重点对常规三段式螺杆的计量段结构进行了研究,分别采用模拟优化和实验优化的方法对计量段槽深和导程进行了优化。并将两种优化方法的优化结果进行对比,结果分析表明:模拟与实验优化结果比较接近,初步形成模拟与实验相结合的优化思路。在螺杆的模拟优化之前,对IMP软件的可靠性和准确性进行初步验证,通过比较模拟和实验获得的螺杆沿程压力、螺杆扭矩,结果表明该软件基本上能够较准确地反映实际加工过程。     

三螺杆挤出机的建压能力与功耗特性

采用有限元数值计算方法模拟了聚合物熔体PP在三螺杆挤出机熔融段的稳态流动过程。借助后处理软件,获得流道两端压力、流量及黏性散热,通过积分后处理得到压差、功耗等评价指标,分析了三螺杆挤出机不同工艺条件下的建压能力和功耗特性。同时进行自制模拟机的实验,通过探究不同工艺条件下压差和能耗的变化规律同数值计算结果进行对比以验证可靠性。研究结果表明:三螺杆挤出机的建压能力随螺杆转速的增加而增强,随喂料量的增加而降低;功耗随螺杆转速和喂料量的增加呈不同趋势。     

螺杆计量段参数对导光板注射成型中PC熔体温度均匀性的影响

使用CFD软件Polyflow对导光板注射成型中螺杆计量段的流场进行了三维非等温数值模拟,讨论分析了不同计量段参数对流道内聚碳酸酯熔体温度的影响。研究发现,计量段参数对轴向温差的影响从大到小依次为螺棱间隙、推力面倾斜角、螺槽深度、导程和螺棱宽度,而对径向温差的影响从大到小依次为螺槽深度、推力面倾斜角、螺棱间隙、导程和螺棱宽度。     

锥形单螺杆挤出机建压能力模型分析

基于固体塞力平衡分析,建立了螺棱圆柱而螺槽渐浅及双锥螺杆的固体输送段压力、固体推进角和功率模型。定量计算或作图分析结果表明,螺槽渐浅锥形螺杆比槽深不变柱螺杆的建压能力要强;建压能力随着锥角的增大而增强,在不同轴向位置锥角对建压能力的影响不同;锥形螺杆固体塞前进角比普通平直螺杆的大,生产率高,固体输送段比功率也会降低。     

基于Adina的注射螺杆计量段塑化过程模拟研究

讨论了在Adina流体分析模块中模拟注射螺杆计量段塑化过程时出现的关于熔体流道模型、材料模型、载荷及边界条件设置等问题。并以PVC塑化螺杆为例,在Adina流体分析模块中模拟分析了螺杆不同转速下,熔体在计量段的压力场、剪切应力场和速度场,并将模拟分析结果与现有研究结果进行了对比验证,其结果基本一致。因此,Adina可用于注射塑化过程的模拟分析,以降低螺杆研发成本和周期。     

Sc-CO_2辅助聚合物挤出中螺杆结构对熔体压力的影响

采用Polyflow软件对双螺杆挤出机内不同螺杆元件所形成流道中的熔体流动进行了模拟,分析了不同螺杆元件的建压能力。结合超临界二氧化碳(Sc-CO2)辅助挤出的螺杆组合原则,对不同螺杆元件组合的螺杆结构进行了挤出实验;并通过对熔体压力的模拟值与实际测量值的比较,分析了不同螺杆结构对熔体压力的影响;另外还针对不同材料的挤出加工确定了相应的螺杆结构。     

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。     

往复注射螺杆计量段三维流场分析

使用流体计算软件Polyflow，对往复注副螺杆计量段进行符合其轴向运动特点的三维流动分析。通过计算得出剪切速率场、压力场、速度场的分布结果，并对分布结果进行分析。通过不同工艺条件变化引起的流场变化，得到流场内部变化的部分规律，并建立了符合注射螺杆工作特点的模拟分析方法。     

振动力场作用下三螺杆挤出机计量段中聚合物挤出的模拟

建立了同向旋转三螺杆挤出机计量段实际流道真实尺寸的三维非牛顿模型，利用ANSYS软件中的FLOTRAN CFD分析功能对该流场进行数值模拟，分析了振动力场作用下挤出机计量段内的黏度分布、压力分布、速度分布以及振幅对流量的影响，同时与无振动状态的挤出特性进行了比较。研究结果表明：振动力场的引入使熔体黏度和流量呈周期性变化，熔体黏度降低，螺棱两侧压差随振幅增大而增大，剪切作用增强，分散性混合能力和分布性混合能力提高。     

沟槽机筒单螺杆挤出机固体输送产量的粒径模型研究

在分析机筒衬套沟槽槽深、螺杆螺槽槽深和加工物料粒径关系的基础上,建立了沟槽机筒单螺杆挤出机3种常见的固体输送段产量粒径模型,该模型可用于研究机筒衬套沟槽槽深、螺杆螺槽槽深和颗粒物料粒径对固体输送机理的影响并定量计算沟槽机筒单螺杆挤出机固体输送段产量。此外,通过不同的机筒和螺杆组合及不同粒径的原料在自制的在线模拟试验机上对该模型进行了验证和试验分析。     

铝粉高填充材料混合流场数值模拟及实验研究

应用Polyflow软件模拟计算了4种总长度为440 mm的螺杆熔体混合段内铝粉高填充复合材料的三维混合流场。通过对各个螺杆组合流道的剪切速率、剪切应力、轴向速度分布等指标进行分析,研究了这4种螺杆组合的流场分布规律和混合性能;分别对每个螺杆组合上的不同元件的混合特性进行直观的对比。数值模拟与实验分析结果表明,带有反向螺纹元件和捏合块的螺杆对填充材料中的超细铝粉具有更优的综合混合能力。     

液压驱动隔膜计量泵的选用和故障处理

计量泵分为柱塞泵、隔膜泵和齿轮泵等多种形式,广泛应用于石油化工等领域。其中液压驱动隔膜计量泵以其无泄漏、可靠性高的特点被某工程塑料装置选用。技术人员在使用过程中通过解决出口压力大幅波动和出口无流量等故障熟悉了解了该型泵的结构特点。     

基于AMESim的WL3200T压机的液压仿真

AMESim是法国IMAGINE公司推出的基于键合图的液压,机械系统建模、仿真及力学分析软件。它以其强大的仿真和分析能力在各个领域得到了广泛的应用。本文选取了WL3200T全自动压砖机的液压系统压制部分为研究对象,利用AMESim对其进行建模、仿真．分析影响液压系统动态特性的主要参数．得出系统压制部分活塞运动速度和液压缸压力的动态特性曲线,为全自动液压压砖机系统设计和参数优化提供了依据。     

Screw-generated forces in granular media: Experimental,computational, and analytical comparison

This study presents an experimental, computational, and analytical comparison of a submerged, double-helix Archimedes screw generating propulsive force against a bed of glass beads. Three screws of different pitch lengths were studied. Each screw was tested at six speeds in approximately 10 trials for a total of 180 experimental trials. These experiments were then replicated in EDEM, a discrete element method (DEM) software program. DEM simulation results for thrust forces in the 30–120 rpm regime had a 5%–20% inflation of forces compared to experimental results. These simulations were then compared with resistive force theory (RFT) plate approximation of the screw geometries. We analyze a superposition-based partition approach to the full-length screws as well as force generation in shortened, one- and two-blade screws. We find that the force generation is dependent on the flow patterns and cannot be reduced to partitioned approximations as with simple intruders. © 2018 American Institute of Chemical Engineers AIChE J, 65: 894–903, 2019     

注射机屏障型螺杆结构设计及其数值模拟研究

根据生产实际设计了几款不同结构参数的屏障型螺杆混炼元件,并借助计算流体动力学软件POLYFLOW分别对各结构进行数值仿真,并对其混炼性能和塑化能力进行了对比。结果表明:增加螺槽深度有助于提高混炼元件作用下的熔体的混合指数,但会导致熔体压力下降;屏障间隙与剪切速率成反比例关系,当屏障间隙约为1 mm时,屏障混炼元件对熔体具有较好的剪切作用和拉伸作用;螺旋角为60°时,屏障元件具有良好的拉伸速率、剪切速率和熔体压力。     

变压吸附数值模拟的研究

从变压吸附的控制方程入手,分析了瞬时平衡模型、线性推动力模型以及孔扩散模型,并对软件化模拟变压吸附系统进行了论述。利用三维流体力学模拟软件,可以模拟并优化吸附塔的气体分布器及其他塔内件,优化程控阀的流体力学性能;利用一维流体力学模拟软件,可以对变压吸附系统管网仿真与优化。利用大型商用软件对变压吸附系统进行从微观的流动细节模拟到宏观的运行状态模拟,是变压吸附数值模拟和系统优化的发展方向。     

Mathematical modeling of melting of polymers in barrier-screw extruders

Some of today's modern screws contain melt-separating secondary (barrier) flights in the transition zone. With increasing utilization of barrier screws, the availability of proper and accurate design methods for the melting zone remains of paramount importance. A modified version of a mathematical model developed by the authors previously is applied to two most common types of barrier screws, viz. —The Mailefer screw (varying pitch and constant depth); —The Barr screw (constant pitch and varying depth). The present analysis provides valuable insight into the operating principles of these screws. A comparative study is presented demonstrating the possible advantages and disadvantages of the Maillefer and Barr screws in relation to conventional compression screws.     

Influence of different cord pitch on the pullout force of steel cord conveyor belt splice

The splice is the weakest part of the entire steel cord conveyor belt. And it occurs steel cord twitch fault frequently. If this fault cannot be dealt with timely and accurately, broken belt accidents would be occurred that affecting the safety of production seriously. In this paper, we investigated the different cord pitch pullout of the steel cord conveyor belt splice by using ABAQUS. The finite element model of the ST630 type steel cord conveyor belt was established, same as to the standard of the experimental sample. The pullout force of length 50.0, 70.0, 80.0 and 100.0 mm single steel cord impacted at steel cord conveyor belt splice was numerically computed respectively. The finite element model consists of rubber, steel cord and failure unit. Failure unit is used to simulate the bonding relationship between steel cord and rubber. Mooney-Rivlin hyper-elastic model for rubber was employed in the numerical simulations. Typical results obtained have been validated by experimental result and the relative error between simulation results and experimental results is within 10%. Simulations were also done for cord pitch of 4.0, 4.5, 6.0, 7.0 and 8.0 mm to study its effect on the pullout force of steel cord conveyor belt splice. The variation of cord pitch at normal impact was found to have influence as long as the cord pitch was different. It provides us the numeric value of the pullout force with the different cord pitch, and conducts us selecting the correct steel cord configuration spacing for the steel cord conveyor belt splice, as well for the steel cord conveyor belt. This is an efficient way for avoiding the steel cord twitch fault and the broken belt accident, while ensuring their high reliability and service life.