塑料挤出成型毕业设计论文
本科毕业设计论文--sj6025挤出机设计

摘要塑料挤出机机筒,它是塑料加工过程中的主要设备之一。
一般挤出机由五大部分组成:挤出部分、传动部分、机头加热冷却系统、电气控制系统塑料是一种高分子合成材料,是当今社会发展的基础材料之一,它广泛应用于各种领域。
挤出部分是挤出机的主体部分,主要作用是:剪切、塑化、捏炼塑料,以一定的压力,均匀连续的向机头输送塑料。
由加料装置、螺杆、机筒、衬套等组成。
其中螺杆分为单头螺杆、双头螺杆和多头螺杆。
衬。
套材料一般为38MoAlACr传动系统的作用是驱动螺杆旋转和根据工艺要求调节螺杆的转速,传动系统由电动机和减速器组成。
机头是挤出机的成形部分,它的作用是使塑料由螺旋运动变为直线运动;在一定的压力下,将塑料挤压成各种所需形状的半成品。
加热冷却系统是为了使塑料很好的挤出,适时控制温度,以防止塑料温度过低或焦灼。
电气控制系统的作用是满足挤出工艺条件的需要,实现对基础机机筒割断温度、机体温度、螺杆转速、驱动扭矩或功率、轴向力等的控制和调节。
由温控、调速和检测装置组成。
挤出机的传动技术有齿轮变速、直流电机和其他方式等若干种。
国内外常用的是由电机通过减速装置带动螺杆进行无级调速传动,国外多用直流电机变速传动,而国内则多用整流子电机变速传动。
挤出机的基本工作过程:带状塑料加入加料口后,在旋转螺杆的作用下塑料被搓成团状沿螺杆槽滚动前进,因螺杆的剪切、压缩和搅拌作用塑料受到进一步塑化,温度和压力逐步提高,呈现出粘流状态,以一定的压力和温度通过机头,最后得到所需的一定形状的半成品。
关键词: 塑料挤出机; 螺杆; 机筒; 机头AbstractThe plastic rod extruding machine abbreviation extrude (also name extruding press), it is an important implement of the plastic reclaiming process.The extrude is made of five parts:the part of extruding;the part of passing;the head;the system of heading and cooling;the electrical control system.The major part of the extrude is the part extruding,it is the most use of shear ,rend and pinch the plastic,under fastness pressure,continuous send plastic to the head ,it made up of fill device ,screw ,barrel ,liner and so on,And the screw is disport of single screw ;double screw ;and component screw.The material of liner is 38CrMoAlA.The part of passing is driving the screw rotation and basic the need of the art factitious process to adjustment the screw royal .The part of passing is made of electrical engineering and reducer.The head is the extruding machine formed part .Its function is :Causes the sizing material to become the translation by the helical motion ;under the certain pressure ,extrudes the sizing materials which need the shape the half-finished product.The system of heating and cooling is for the plastic well extrusion ,we control the temperate to prevent the temperate too low or born.The electrical control system is for the need of press,control thetemperate of the barrel and the head ,the royal of the screw ,drive the torsion or power ,and adjustment the head ,the royal of the screw ,driver the torsion or power ,and adjustment the force of the axial ,is made of the temperate controller ,the speed adjustment system,and the device of test.The extrude fundamental process is this:get the plastic to the filler,under the shear of the screw ,the plastic was made small ball,because of the screw’s shear pressure and stirring ,the plastic was farther re nd and plastic ,the temperate and the pressure get higher ,and the plastic get plastic flow,under fastness pressure though the head ,the last get the production you need.Key words: Plastic extrude ; Screw ; Barrel ; Head目录第一章挤出机的主要性能参数 (4)1.1 螺杆区域划分及材料 (4)1.1.1 螺杆直径 (4)1.1.2 螺杆长径比 (4)1.1.3 转速与喂料方式的关系 (4)1.2 挤出机功率 (5)1.4 生产能力Q (6)第二章电机的选择 (7)第三章减速器设计计算 (7)3.1 传动部分设计计算 (8)3.1.1 传动比计算及分配 (8)3.1.2 各轴转速 (8)3.1.3 各轴功率 (9)3.1.4 各轴转矩 (9)3.2 齿轮设计 (10)3.2.1 高速级齿轮传动 (10)3.2.2 低速级齿轮传动 (15)3.3 速比齿轮轴及其上轴承的设计、选择和校核 (20)3.3.1 基本轴径的设计 (20)3.4 各轴上联接齿轮的键的选取及校核 (35)3.4.1低速级齿轮的键及其校核 (36)3.4.2中间级齿轮的键及其校核 (37)第四章螺杆的设计与校核 (38)4.1 螺杆材料 (38)4.2 螺杆形式 (38)4.3 螺杆参数 (38)4.4 螺杆结构 (39)4.5 螺纹的断面形状 (39)4.6 校核 (39)第五章机筒的设计及强度校核 (40)5.1 机筒结构设计及材料选择 (40)5.2 机筒参数 (40)5.3 校核 (40)第六章其他零部件的设计与校核 (42)6.1 螺杆与轴联接处的花键的选择与校核 (42)6.1.1 花键挤压强度校核 (42)6.2 推力轴承的选择与校核 (42)6.2.1 校核 (43)6.2.2 寿命计算 (43)6.3 联轴器的选择与校核 (43)6.4 螺杆与机筒的组合设计 (44)6.5 机头的设计 (44)6.6 温度控制 (44)结语 (45)参考文献 (46)致谢 (47)引言1.1 论文的研究背景及意义塑料是一种高分子合成材料,是当今社会发展的基础材料之一,它广泛应用于各种领域。
塑料件模具设计毕业设计论文.doc

塑料件模具设计摘要塑料作为高分子化学和材料科学发展的重要成果,早已为人们熟悉,塑料产品已经成为人类生产和生活中不可缺少的重要组成部分。
多年来,塑料产品制造业一直在迅速发展,而当前全球范围的以塑料代替金属的趋势又进一步加速了这一发展速度。
塑料产品一般采用模塑成型方法生产,因而塑料模具早已成为一种重要的生产工艺装备,在国民经济中起着越来越重要的作用。
随着塑料产品在家电、电子、机械等产品和日常用品中越来越广泛应用。
为保证产品质量,对塑料成型工艺和塑料模具提出较高要求,采用UG三维软件进行注塑模具设计的方法更加适应产品更新换代和提高质量要求,同时便于后续的数控加工。
本文从分析塑料件的材料、形状等进行塑料成型工艺分析,对塑件增加拔模斜度等工艺参数,对塑件三维造型,计算塑件质量,初选注塑机;对塑件进行模具成型分析,对模具分型面、浇注口位置、主流道、分流道、浇口形式和冷料穴进行设计,结合产品生产批量,设计模具机构,对模具的成型零件和功能零件具体设计和布置,运用UG软件,设计模具的三维造型,绘出模具总装图纸;为保证计算产品质量和模具的强度等考虑。
计算成型零件的尺寸和公差,计算侧抽芯机构的参数,并对模具使用的注塑机进行校核,保证成型零件的强度、精度满足要求,并对注塑机校核,确保塑料量、推出距离、模具安装尺寸满足设计模具要求。
关键词:塑料;UG建模;塑料模具;CADABSTRACTPlastic, as the important achievement of polymer chemistry and material science, has long been familiar with. Plastic products have become one of the indispensable comp onents in human’s production and daily life. Over the years the plastic product manufacturing industry has been development. Generally plastic products are manufactured by molding therefore plastic molds have become an important production device and play an increasingly important role in the national economy. The use of plastic products in home appliances, machinery and other daily necessities has become more and more wide and to ensure the quality, the three-dimensional software for injection mold design has adapted to the high demand of product upgrading and improving.This paper is to analyze the plastic molding process from the material, shape and ETC. of the shell of electric appliance; to analyze the increased taper and other parameters of plastic parts, three-dimensional shape and the mass calculation to select injection molding machine; to analyze the parting line, nozzle position, runner, gate forms and cold slug combined with production quantities to design and organize the molding parts and functional parts ; to use UG software and three-dimensional molding of design to make the assembly drawings; to ensure calculating the product quality, mold strength and other considerations. In order to make sure the injection volume and the extrusion distance to meet the product requirements, the dimensions and tolerances of molded parts and the side pumping mechanism will be calculated and also the injection molding machine will be checked.Key Word: plastic, modeling, injection mold, CAD目录摘要................................................................................................................................................................ I I ABSTRACT........................................................................................................................................................ I II 第一章绪论 (1)1.1 塑料在轻工业上的应用 (1)1.2 工程塑料ABS的性能及应用 (1)1.3 注塑成型原理 (3)第二章塑件的结构工艺分析 (5)2.1 塑件的几何形状分析 (5)2.2 塑件原材料的成型特性分析 (6)2.3 塑件的结构工艺性分析 (7)2.3.1 塑件的尺寸精度分析 (7)2.3.2 塑件的表面质量分析 (8)2.3.3 塑件的成型工艺分析 (8)2.3.4 塑件的生产批量 (8)2.4 初选注射机 (8)2.5 本章小结 (11)第三章塑件模具结构的设计 (12)3.1 分型面的选择 (12)3.2 浇注系统的设计 (13)3.2.1 浇注口位置的选择 (14)3.2.2 主流道和定位圈的设计 (15)3.2.3 分流道的设计 (17)3.2.4 浇口的设计 (18)3.2.5 冷料穴的设计 (20)3.3 模具结构设计 (21)3.3.1 型腔布置 (23)3.3.2 成型零件的结构设计 (23)3.3.3 导向定位机构设计的确定 (23)3.3.4 推出机构设计 (23)3.3.5 冷却系统设计 (24)3.3.6 排气系统的设计 (24)3.4 本章小结 (26)第四章基于UG软件的三维模具设计 (29)4.1 UG简介 (27)4.2 模具设计 (28)4.2.1 塑件分模 (28)4.3 本章小结 (38)第五章毕业设计总结与展望 (36)5.1 毕业设计总结 (39)5.2 展望 (40)参考文献 (38)第一章绪论1.1 塑料在轻工业上的应用塑料是一种具有可塑性的人造高分子有机化合物(树脂),是指以有机合成树脂为主要成分,加入或不加入其他配合材料而构成的人造材料,它通常在加热、加压条件下可塑成具有一定形状的器件。
塑料挤出机毕业设计范文

塑料挤出机螺杆、机筒设计初探[内容摘要]首先介绍聚氯乙烯板挤出成型生产工艺,单螺杆挤出机的工作原理、基本结构及各系统在工作中的作用,根据设计任务书要求确定挤出机的基本参数,并对挤出机主要零件螺杆和机筒进行了设计,最后对螺杆和机筒的制造要求、修复方法提出了自己的一些看法。
[关键词]挤出成型挤出机螺杆机筒设计一、PVC塑料板挤出成型工艺及主要工艺流程挤出成型是橡胶工业的基本加工工艺之一。
它是指利用挤出机及其辅机,使胶料在螺杆的推动下,连续不断地向前运动,再借助于口型挤出各种所需形状的半成品,然后由特定的辅机配合,来完成挤出成型或其他作业的工艺过程。
挤出成型工艺的优点主要是操作简单、经济,半成品质地均匀、致密,容易变换规格和断面形状,设备占地面积小,结构简单,造价低,灵活机动性大,生产能力大,且能连续操作。
(一)聚氯乙烯板挤出成型生产工艺流程及主要装置1、工艺流程塑料板的挤出成型可用聚氯乙烯﹑聚乙烯﹑聚丙烯﹑聚碳酸酯﹑ABS﹑聚偏氟乙烯和聚苯乙烯等树脂。
其生产工艺顺序如图一。
图一PVC-U异型材的生产工艺路线主要分为单螺杆挤出机成型工艺和双螺杆挤出机成型工艺。
单螺杆挤出成型工艺适用于小批量、小规格异型材生产及装饰型材生产。
其塑料板挤出机成型设备生产线如图二。
图二塑料板挤出生产线1—挤出机2—成型模具3—三辊压光机4—冷却输送辊组5—切边装置6—牵引装置7—切断机8—制品检查堆放平台2、主要装置(1)挤出成型装置挤出机与成型模具,它是制件成型的主要部件,熔融塑料通过它获得一定的几何截面和尺寸。
本设计将主要针对挤出机的工作原理进行分析研究。
(2)冷却定型装置该装置包括真空定型和水冷却两部分。
当温度为190℃左右,PVC-U熔融型坯从机头口模出口后,立即进入冷却定型模。
模内抽真空,使型材外壁和定型模具表面贴紧,并用水通过定型套进行冷却定型。
对真空吸附要求吸附力大而且均匀,定型套分型要求密封性好,特别是在筋与棱角处吸附要好,以保证型材外观和尺寸精度及表观质量。
(完整版)模具塑料模毕业设计论文

优秀论文审核通过未经允许切勿外传毕业设计说明书目录前言……………………………………………(一)塑料工艺分析…………………………………(二)1、原材料的分析2、塑料的结构分析3、表面质量分析4、尺寸精度分析塑件的体积与质量……………………………(三)注射工艺参数的确定…………………………(四)结构设计………………………………………(五)1、分型面的选择2、型腔的排列方式3、浇注系统的设计①、主流道的设计②、分流道的设计③、浇口设计4、成型零件的结构设计①、凹摸的结构设计②、凸模的结构设计计算……………………………………………(六)1、型芯、型腔尺寸的计算①凹模有关尺寸的计算②、模具型新位置尺寸计算③、模具型新位置尺寸计算2、侧壁及底板厚度计算3、加热或冷却有关计算4、闭合高度的计算5、注射机有关参数的校核模具工作原理…………………………………(七)设计的特点……………………………………(八)制造……………………………………………(九)参考文献………………………………………(十)后记……………………………………………(十一)题目:塑件名称: 肥皂盒材料: ABS生产批量: 大批量生产,无毛边零件图如右图:内容提要本课题主要是针对盒盖的模具设计,通过对塑件进行工艺的分析和比较,最终设计出一副注塑模。
该课题从产品结构工艺性,具体模具结构出发,对模具的浇注系统、模具成型部分的结构、顶出系统、冷却系统、注塑机的选择及有关参数的校核、都有详细的设计,同时并简单的编制了模具的加工工艺。
通过整个设计过程表明该模具能够达到此塑件所要求的加工工艺。
根据题目设计的主要任务是盒盖注塑模具的设计。
也就是设计一副注塑模具来生产盒盖塑件产品,以实现自动化提高产量。
针对盒盖的具体结构,该模具是点浇口的双分型面注射模具。
由于塑件内侧有六个小凸台,不需要设置斜导柱,固采用活动镶件的结构形式。
其优点在于简化机构,使模具外形缩小,大大降低了模具的制造成本。
(完整版)20塑料注塑模具毕业设计论文

优秀论文审核通过未经允许切勿外传摘要本文是关于外壳塑料件设计,主要内容包括塑件的成形工艺分析,模具结构形式的确定,分型面位置的确定, 浇注系统的形式和浇口的设计 , 成形零件的结构设计和计算 , 模架的确定和标准件的选用 , 合模导向机构的设计 , 脱模推出机制造工艺构的设计等。
在正确分析塑件工艺特点和材料的性能后,涉及模具结构、强度、寿命计算及熔融塑料在模具中流动预测等复杂的工程运算问题;运用 CAD、三维软件等不同的软件分别对模具的设计、制造和产品质量进行分析。
塑料件注塑模设计,采用一般精度,利用 CAD、三维设计设计软件来设机械设计计或分析注射模的机械设计机械设计成型零部件,浇注系统,导向部机械设计机械设计件和脱模机械设计机构等等。
综合运用机械设计了专业基础、专业课机械设计知识设计,机械设计其核心知机械设计识是塑料成型模具、加工工艺机械设计材料成型技术基础、机械设计、塑料设计设计成型工艺、计算机辅助设计、模具 CAD等。
关键词:模架 , 标准件 , 脱模推出机构 .AbstractThis paper is about the design of plastic injection mold,cone-shaped include plastic parts forming process analysis, determination of die structure form, parting surface positioning, gating system forms and runner design, forming parts structuredesign and calculation, the determination of the formwork andstandard parts choose, shut the mould design of steering mechanism, stripping out institution design, etc.In the correct analysis plastics technology characteristics and PP material performance, involving the mould structure, strength, lifetime calculation and molten plastic mould flowprediction in complex engineering computation problem; Using CAD, such different software UG respectively to mold of design, manufacturing and product quality analysis. Tapered plastic injection mold design, use general accuracy, use CAD, UGto design or analysis of injection mold, gating system, discusses guidecomponents and moulding mechanism, etc. Comprehensive use of the professional basis, professional class design, and its core knowledge is plastic molding, material molding technology base,mechanical design, plastic injection molding process, computeraided design, mould CAD, etc.Keywords:formwork,standard parts,stripping out institution design目录摘要 (1)ABSTRACT (2)目录 . (3)第 1 章引言 (1)第 2 章塑件分析 (6)2.1 塑件模具结构分析........................................2.2.1 尺寸精度分析 ...............................................2.2.2 表面质量分析 ................................................2.2.3 计算塑件的体积和重量 .........................................2.2.4 塑件注射工艺参数的确模具设计模具设计定 ..........................2.2 塑件材料的选择.........................................2.2.1 材料 ABS的注塑设计设计成型参数.................................2.2.2 材料 ABS性能...............................................第 3 章注射模的结构设计 (10)3.1 型腔数目的确定........................................3.2 型腔的分布. ..........................................3.3 分型面的设计计........................................6 6 6 67 78 81010113.4 浇注系统设设计 (11)3.4.1 主流道 . (12)3.4.2 分流道设计 (13)3.4.3 浇口形式及位置的选择 (13)3.4.4 剪切速率的校核 (14)3.4.5 主流道剪切速率校核 (15)3.4.6 浇口剪切速速率的校核 . (15)3.5 成型零件结构设计. (15)3.5.1 定模的结构设计 (15)3.5.2 动模的结构设计 (16)3.5.4 型腔和型芯工作尺寸计算 (17)3.6 推杆机构设计. (18)3.6.1 脱模机构的选用原则 (18)3.6.2 脱模力的计算 (18)3.6.3 推杆的设计 (19)3.7 冷却系统的设计. (20)3.7.1 设计原则 (20)3.7.2 冷却时间的确定 (21)3.7.3 模具加热和冷却系统的计算 (21)第 4 章注塑机校核 (24)4.4.1 模具闭合高度的确定 (24)4.4.2 由锁模力选定注射机 (24)4.4.3 最大注塑量的校核 (25)4.4.4 锁模力的校核 (25)4.4.5塑化能力的校核 (25)第 6 章模具工作原理 (26)参考文献 (27)第1章引言随着中国国民经济的高速发展,各相关行业对于塑料模具需求越来越多,要求也日益提高。
塑料挤出成型毕业设计论文

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毕业设计论文塑料注射成型

Modeling of morphology evolution in the injection moldingprocess of thermoplastic polymersR.Pantani,I.Coccorullo,V.Speranza,G.Titomanlio* Department of Chemical and Food Engineering,University of Salerno,via Ponte don Melillo,I-84084Fisciano(Salerno),Italy Received13May2005;received in revised form30August2005;accepted12September2005AbstractA thorough analysis of the effect of operative conditions of injection molding process on the morphology distribution inside the obtained moldings is performed,with particular reference to semi-crystalline polymers.The paper is divided into two parts:in the first part,the state of the art on the subject is outlined and discussed;in the second part,an example of the characterization required for a satisfactorily understanding and description of the phenomena is presented,starting from material characterization,passing through the monitoring of the process cycle and arriving to a deep analysis of morphology distribution inside the moldings.In particular,fully characterized injection molding tests are presented using an isotactic polypropylene,previously carefully characterized as far as most of properties of interest.The effects of both injectionflow rate and mold temperature are analyzed.The resulting moldings morphology(in terms of distribution of crystallinity degree,molecular orientation and crystals structure and dimensions)are analyzed by adopting different experimental techniques(optical,electronic and atomic force microscopy,IR and WAXS analysis).Final morphological characteristics of the samples are compared with the predictions of a simulation code developed at University of Salerno for the simulation of the injection molding process.q2005Elsevier Ltd.All rights reserved.Keywords:Injection molding;Crystallization kinetics;Morphology;Modeling;Isotactic polypropyleneContents1.Introduction (1186)1.1.Morphology distribution in injection molded iPP parts:state of the art (1189)1.1.1.Modeling of the injection molding process (1190)1.1.2.Modeling of the crystallization kinetics (1190)1.1.3.Modeling of the morphology evolution (1191)1.1.4.Modeling of the effect of crystallinity on rheology (1192)1.1.5.Modeling of the molecular orientation (1193)1.1.6.Modeling of theflow-induced crystallization (1195)ments on the state of the art (1197)2.Material and characterization (1198)2.1.PVT description (1198)*Corresponding author.Tel.:C39089964152;fax:C39089964057.E-mail address:gtitomanlio@unisa.it(G.Titomanlio).2.2.Quiescent crystallization kinetics (1198)2.3.Viscosity (1199)2.4.Viscoelastic behavior (1200)3.Injection molding tests and analysis of the moldings (1200)3.1.Injection molding tests and sample preparation (1200)3.2.Microscopy (1202)3.2.1.Optical microscopy (1202)3.2.2.SEM and AFM analysis (1202)3.3.Distribution of crystallinity (1202)3.3.1.IR analysis (1202)3.3.2.X-ray analysis (1203)3.4.Distribution of molecular orientation (1203)4.Analysis of experimental results (1203)4.1.Injection molding tests (1203)4.2.Morphology distribution along thickness direction (1204)4.2.1.Optical microscopy (1204)4.2.2.SEM and AFM analysis (1204)4.3.Morphology distribution alongflow direction (1208)4.4.Distribution of crystallinity (1210)4.4.1.Distribution of crystallinity along thickness direction (1210)4.4.2.Crystallinity distribution alongflow direction (1212)4.5.Distribution of molecular orientation (1212)4.5.1.Orientation along thickness direction (1212)4.5.2.Orientation alongflow direction (1213)4.5.3.Direction of orientation (1214)5.Simulation (1214)5.1.Pressure curves (1215)5.2.Morphology distribution (1215)5.3.Molecular orientation (1216)5.3.1.Molecular orientation distribution along thickness direction (1216)5.3.2.Molecular orientation distribution alongflow direction (1216)5.3.3.Direction of orientation (1217)5.4.Crystallinity distribution (1217)6.Conclusions (1217)References (1219)1.IntroductionInjection molding is one of the most widely employed methods for manufacturing polymeric products.Three main steps are recognized in the molding:filling,packing/holding and cooling.During thefilling stage,a hot polymer melt rapidlyfills a cold mold reproducing a cavity of the desired product shape. During the packing/holding stage,the pressure is raised and extra material is forced into the mold to compensate for the effects that both temperature decrease and crystallinity development determine on density during solidification.The cooling stage starts at the solidification of a thin section at cavity entrance (gate),starting from that instant no more material can enter or exit from the mold impression and holding pressure can be released.When the solid layer on the mold surface reaches a thickness sufficient to assure required rigidity,the product is ejected from the mold.Due to the thermomechanical history experienced by the polymer during processing,macromolecules in injection-molded objects present a local order.This order is referred to as‘morphology’which literally means‘the study of the form’where form stands for the shape and arrangement of parts of the object.When referred to polymers,the word morphology is adopted to indicate:–crystallinity,which is the relative volume occupied by each of the crystalline phases,including mesophases;–dimensions,shape,distribution and orientation of the crystallites;–orientation of amorphous phase.R.Pantani et al./Prog.Polym.Sci.30(2005)1185–1222 1186R.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221187Apart from the scientific interest in understandingthe mechanisms leading to different order levels inside a polymer,the great technological importance of morphology relies on the fact that polymer character-istics (above all mechanical,but also optical,electrical,transport and chemical)are to a great extent affected by morphology.For instance,crystallinity has a pro-nounced effect on the mechanical properties of the bulk material since crystals are generally stiffer than amorphous material,and also orientation induces anisotropy and other changes in mechanical properties.In this work,a thorough analysis of the effect of injection molding operative conditions on morphology distribution in moldings with particular reference to crystalline materials is performed.The aim of the paper is twofold:first,to outline the state of the art on the subject;second,to present an example of the characterization required for asatisfactorilyR.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221188understanding and description of the phenomena, starting from material description,passing through the monitoring of the process cycle and arriving to a deep analysis of morphology distribution inside the mold-ings.To these purposes,fully characterized injection molding tests were performed using an isotactic polypropylene,previously carefully characterized as far as most of properties of interest,in particular quiescent nucleation density,spherulitic growth rate and rheological properties(viscosity and relaxation time)were determined.The resulting moldings mor-phology(in terms of distribution of crystallinity degree, molecular orientation and crystals structure and dimensions)was analyzed by adopting different experimental techniques(optical,electronic and atomic force microscopy,IR and WAXS analysis).Final morphological characteristics of the samples were compared with the predictions of a simulation code developed at University of Salerno for the simulation of the injection molding process.The effects of both injectionflow rate and mold temperature were analyzed.1.1.Morphology distribution in injection molded iPP parts:state of the artFrom many experimental observations,it is shown that a highly oriented lamellar crystallite microstructure, usually referred to as‘skin layer’forms close to the surface of injection molded articles of semi-crystalline polymers.Far from the wall,the melt is allowed to crystallize three dimensionally to form spherulitic structures.Relative dimensions and morphology of both skin and core layers are dependent on local thermo-mechanical history,which is characterized on the surface by high stress levels,decreasing to very small values toward the core region.As a result,the skin and the core reveal distinct characteristics across the thickness and also along theflow path[1].Structural and morphological characterization of the injection molded polypropylene has attracted the interest of researchers in the past three decades.In the early seventies,Kantz et al.[2]studied the morphology of injection molded iPP tensile bars by using optical microscopy and X-ray diffraction.The microscopic results revealed the presence of three distinct crystalline zones on the cross-section:a highly oriented non-spherulitic skin;a shear zone with molecular chains oriented essentially parallel to the injection direction;a spherulitic core with essentially no preferred orientation.The X-ray diffraction studies indicated that the skin layer contains biaxially oriented crystallites due to the biaxial extensionalflow at theflow front.A similar multilayered morphology was also reported by Menges et al.[3].Later on,Fujiyama et al.[4] investigated the skin–core morphology of injection molded iPP samples using X-ray Small and Wide Angle Scattering techniques,and suggested that the shear region contains shish–kebab structures.The same shish–kebab structure was observed by Wenig and Herzog in the shear region of their molded samples[5].A similar investigation was conducted by Titomanlio and co-workers[6],who analyzed the morphology distribution in injection moldings of iPP. They observed a skin–core morphology distribution with an isotropic spherulitic core,a skin layer characterized by afine crystalline structure and an intermediate layer appearing as a dark band in crossed polarized light,this layer being characterized by high crystallinity.Kalay and Bevis[7]pointed out that,although iPP crystallizes essentially in the a-form,a small amount of b-form can be found in the skin layer and in the shear region.The amount of b-form was found to increase by effect of high shear rates[8].A wide analysis on the effect of processing conditions on the morphology of injection molded iPP was conducted by Viana et al.[9]and,more recently, by Mendoza et al.[10].In particular,Mendoza et al. report that the highest level of crystallinity orientation is found inside the shear zone and that a high level of orientation was also found in the skin layer,with an orientation angle tilted toward the core.It is rather difficult to theoretically establish the relationship between the observed microstructure and processing conditions.Indeed,a model of the injection molding process able to predict morphology distribution in thefinal samples is not yet available,even if it would be of enormous strategic importance.This is mainly because a complete understanding of crystallization kinetics in processing conditions(high cooling rates and pressures,strong and complexflowfields)has not yet been reached.In this section,the most relevant aspects for process modeling and morphology development are identified. In particular,a successful path leading to a reliable description of morphology evolution during polymer processing should necessarily pass through:–a good description of morphology evolution under quiescent conditions(accounting all competing crystallization processes),including the range of cooling rates characteristic of processing operations (from1to10008C/s);R.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221189–a description capturing the main features of melt morphology(orientation and stretch)evolution under processing conditions;–a good coupling of the two(quiescent crystallization and orientation)in order to capture the effect of crystallinity on viscosity and the effect offlow on crystallization kinetics.The points listed above outline the strategy to be followed in order to achieve the basic understanding for a satisfactory description of morphology evolution during all polymer processing operations.In the following,the state of art for each of those points will be analyzed in a dedicated section.1.1.1.Modeling of the injection molding processThefirst step in the prediction of the morphology distribution within injection moldings is obviously the thermo-mechanical simulation of the process.Much of the efforts in the past were focused on the prediction of pressure and temperature evolution during the process and on the prediction of the melt front advancement [11–15].The simulation of injection molding involves the simultaneous solution of the mass,energy and momentum balance equations.Thefluid is non-New-tonian(and viscoelastic)with all parameters dependent upon temperature,pressure,crystallinity,which are all function of pressibility cannot be neglected as theflow during the packing/holding step is determined by density changes due to temperature, pressure and crystallinity evolution.Indeed,apart from some attempts to introduce a full 3D approach[16–19],the analysis is currently still often restricted to the Hele–Shaw(or thinfilm) approximation,which is warranted by the fact that most injection molded parts have the characteristic of being thin.Furthermore,it is recognized that the viscoelastic behavior of the polymer only marginally influences theflow kinematics[20–22]thus the melt is normally considered as a non-Newtonian viscousfluid for the description of pressure and velocity gradients evolution.Some examples of adopting a viscoelastic constitutive equation in the momentum balance equations are found in the literature[23],but the improvements in accuracy do not justify a considerable extension of computational effort.It has to be mentioned that the analysis of some features of kinematics and temperature gradients affecting the description of morphology need a more accurate description with respect to the analysis of pressure distributions.Some aspects of the process which were often neglected and may have a critical importance are the description of the heat transfer at polymer–mold interface[24–26]and of the effect of mold deformation[24,27,28].Another aspect of particular interest to the develop-ment of morphology is the fountainflow[29–32], which is often neglected being restricted to a rather small region at theflow front and close to the mold walls.1.1.2.Modeling of the crystallization kineticsIt is obvious that the description of crystallization kinetics is necessary if thefinal morphology of the molded object wants to be described.Also,the development of a crystalline degree during the process influences the evolution of all material properties like density and,above all,viscosity(see below).Further-more,crystallization kinetics enters explicitly in the generation term of the energy balance,through the latent heat of crystallization[26,33].It is therefore clear that the crystallinity degree is not only a result of simulation but also(and above all)a phenomenon to be kept into account in each step of process modeling.In spite of its dramatic influence on the process,the efforts to simulate the injection molding of semi-crystalline polymers are crude in most of the commercial software for processing simulation and rather scarce in the fleur and Kamal[34],Papatanasiu[35], Titomanlio et al.[15],Han and Wang[36],Ito et al.[37],Manzione[38],Guo and Isayev[26],and Hieber [25]adopted the following equation(Kolmogoroff–Avrami–Evans,KAE)to predict the development of crystallinityd xd tZð1K xÞd d cd t(1)where x is the relative degree of crystallization;d c is the undisturbed volume fraction of the crystals(if no impingement would occur).A significant improvement in the prediction of crystallinity development was introduced by Titoman-lio and co-workers[39]who kept into account the possibility of the formation of different crystalline phases.This was done by assuming a parallel of several non-interacting kinetic processes competing for the available amorphous volume.The evolution of each phase can thus be described byd x id tZð1K xÞd d c id t(2)where the subscript i stands for a particular phase,x i is the relative degree of crystallization,x ZPix i and d c iR.Pantani et al./Prog.Polym.Sci.30(2005)1185–1222 1190is the expectancy of volume fraction of each phase if no impingement would occur.Eq.(2)assumes that,for each phase,the probability of the fraction increase of a single crystalline phase is simply the product of the rate of growth of the corresponding undisturbed volume fraction and of the amount of available amorphous fraction.By summing up the phase evolution equations of all phases(Eq.(2))over the index i,and solving the resulting differential equation,one simply obtainsxðtÞZ1K exp½K d cðtÞ (3)where d c Z Pid c i and Eq.(1)is recovered.It was shown by Coccorullo et al.[40]with reference to an iPP,that the description of the kinetic competition between phases is crucial to a reliable prediction of solidified structures:indeed,it is not possible to describe iPP crystallization kinetics in the range of cooling rates of interest for processing(i.e.up to several hundreds of8C/s)if the mesomorphic phase is neglected:in the cooling rate range10–1008C/s, spherulite crystals in the a-phase are overcome by the formation of the mesophase.Furthermore,it has been found that in some conditions(mainly at pressures higher than100MPa,and low cooling rates),the g-phase can also form[41].In spite of this,the presence of different crystalline phases is usually neglected in the literature,essentially because the range of cooling rates investigated for characterization falls in the DSC range (well lower than typical cooling rates of interest for the process)and only one crystalline phase is formed for iPP at low cooling rates.It has to be noticed that for iPP,which presents a T g well lower than ambient temperature,high values of crystallinity degree are always found in solids which passed through ambient temperature,and the cooling rate can only determine which crystalline phase forms, roughly a-phase at low cooling rates(below about 508C/s)and mesomorphic phase at higher cooling rates.The most widespread approach to the description of kinetic constant is the isokinetic approach introduced by Nakamura et al.According to this model,d c in Eq.(1)is calculated asd cðtÞZ ln2ðt0KðTðsÞÞd s2 435n(4)where K is the kinetic constant and n is the so-called Avrami index.When introduced as in Eq.(4),the reciprocal of the kinetic constant is a characteristic time for crystallization,namely the crystallization half-time, t05.If a polymer is cooled through the crystallization temperature,crystallization takes place at the tempera-ture at which crystallization half-time is of the order of characteristic cooling time t q defined ast q Z D T=q(5) where q is the cooling rate and D T is a temperature interval over which the crystallization kinetic constant changes of at least one order of magnitude.The temperature dependence of the kinetic constant is modeled using some analytical function which,in the simplest approach,is described by a Gaussian shaped curve:KðTÞZ K0exp K4ln2ðT K T maxÞ2D2(6)The following Hoffman–Lauritzen expression[42] is also commonly adopted:K½TðtÞ Z K0exp KUÃR$ðTðtÞK T NÞ!exp KKÃ$ðTðtÞC T mÞ2TðtÞ2$ðT m K TðtÞÞð7ÞBoth equations describe a bell shaped curve with a maximum which for Eq.(6)is located at T Z T max and for Eq.(7)lies at a temperature between T m(the melting temperature)and T N(which is classically assumed to be 308C below the glass transition temperature).Accord-ing to Eq.(7),the kinetic constant is exactly zero at T Z T m and at T Z T N,whereas Eq.(6)describes a reduction of several orders of magnitude when the temperature departs from T max of a value higher than2D.It is worth mentioning that only three parameters are needed for Eq.(6),whereas Eq.(7)needs the definition offive parameters.Some authors[43,44]couple the above equations with the so-called‘induction time’,which can be defined as the time the crystallization process starts, when the temperature is below the equilibrium melting temperature.It is normally described as[45]Dt indDtZðT0m K TÞat m(8)where t m,T0m and a are material constants.It should be mentioned that it has been found[46,47]that there is no need to explicitly incorporate an induction time when the modeling is based upon the KAE equation(Eq.(1)).1.1.3.Modeling of the morphology evolutionDespite of the fact that the approaches based on Eq.(4)do represent a significant step toward the descriptionR.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221191of morphology,it has often been pointed out in the literature that the isokinetic approach on which Nakamura’s equation (Eq.(4))is based does not describe details of structure formation [48].For instance,the well-known experience that,with many polymers,the number of spherulites in the final solid sample increases strongly with increasing cooling rate,is indeed not taken into account by this approach.Furthermore,Eq.(4)describes an increase of crystal-linity (at constant temperature)depending only on the current value of crystallinity degree itself,whereas it is expected that the crystallization rate should depend also on the number of crystalline entities present in the material.These limits are overcome by considering the crystallization phenomenon as the consequence of nucleation and growth.Kolmogoroff’s model [49],which describes crystallinity evolution accounting of the number of nuclei per unit volume and spherulitic growth rate can then be applied.In this case,d c in Eq.(1)is described asd ðt ÞZ C m ðt 0d N ðs Þd s$ðt sG ðu Þd u 2435nd s (9)where C m is a shape factor (C 3Z 4/3p ,for spherical growth),G (T (t ))is the linear growth rate,and N (T (t ))is the nucleation density.The following Hoffman–Lauritzen expression is normally adopted for the growth rateG ½T ðt Þ Z G 0exp KUR $ðT ðt ÞK T N Þ!exp K K g $ðT ðt ÞC T m Þ2T ðt Þ2$ðT m K T ðt ÞÞð10ÞEqs.(7)and (10)have the same form,however the values of the constants are different.The nucleation mechanism can be either homo-geneous or heterogeneous.In the case of heterogeneous nucleation,two equations are reported in the literature,both describing the nucleation density as a function of temperature [37,50]:N ðT ðt ÞÞZ N 0exp ½j $ðT m K T ðt ÞÞ (11)N ðT ðt ÞÞZ N 0exp K 3$T mT ðt ÞðT m K T ðt ÞÞ(12)In the case of homogeneous nucleation,the nucleation rate rather than the nucleation density is function of temperature,and a Hoffman–Lauritzen expression isadoptedd N ðT ðt ÞÞd t Z N 0exp K C 1ðT ðt ÞK T N Þ!exp KC 2$ðT ðt ÞC T m ÞT ðt Þ$ðT m K T ðt ÞÞð13ÞConcentration of nucleating particles is usually quite significant in commercial polymers,and thus hetero-geneous nucleation becomes the dominant mechanism.When Kolmogoroff’s approach is followed,the number N a of active nuclei at the end of the crystal-lization process can be calculated as [48]N a ;final Zðt final 0d N ½T ðs Þd sð1K x ðs ÞÞd s (14)and the average dimension of crystalline structures can be attained by geometrical considerations.Pantani et al.[51]and Zuidema et al.[22]exploited this method to describe the distribution of crystallinity and the final average radius of the spherulites in injection moldings of polypropylene;in particular,they adopted the following equationR Z ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi3x a ;final 4p N a ;final 3s (15)A different approach is also present in the literature,somehow halfway between Nakamura’s and Kolmo-goroff’s models:the growth rate (G )and the kinetic constant (K )are described independently,and the number of active nuclei (and consequently the average dimensions of crystalline entities)can be obtained by coupling Eqs.(4)and (9)asN a ðT ÞZ 3ln 24p K ðT ÞG ðT Þ 3(16)where heterogeneous nucleation and spherical growth is assumed (Avrami’s index Z 3).Guo et al.[43]adopted this approach to describe the dimensions of spherulites in injection moldings of polypropylene.1.1.4.Modeling of the effect of crystallinity on rheology As mentioned above,crystallization has a dramatic influence on material viscosity.This phenomenon must obviously be taken into account and,indeed,the solidification of a semi-crystalline material is essen-tially caused by crystallization rather than by tempera-ture in normal processing conditions.Despite of the importance of the subject,the relevant literature on the effect of crystallinity on viscosity isR.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221192rather scarce.This might be due to the difficulties in measuring simultaneously rheological properties and crystallinity evolution during the same tests.Apart from some attempts to obtain simultaneous measure-ments of crystallinity and viscosity by special setups [52,53],more often viscosity and crystallinity are measured during separate tests having the same thermal history,thus greatly simplifying the experimental approach.Nevertheless,very few works can be retrieved in the literature in which(shear or complex) viscosity can be somehow linked to a crystallinity development.This is the case of Winter and co-workers [54],Vleeshouwers and Meijer[55](crystallinity evolution can be drawn from Swartjes[56]),Boutahar et al.[57],Titomanlio et al.[15],Han and Wang[36], Floudas et al.[58],Wassner and Maier[59],Pantani et al.[60],Pogodina et al.[61],Acierno and Grizzuti[62].All the authors essentially agree that melt viscosity experiences an abrupt increase when crystallinity degree reaches a certain‘critical’value,x c[15]. However,little agreement is found in the literature on the value of this critical crystallinity degree:assuming that x c is reached when the viscosity increases of one order of magnitude with respect to the molten state,it is found in the literature that,for iPP,x c ranges from a value of a few percent[15,62,60,58]up to values of20–30%[58,61]or even higher than40%[59,54,57].Some studies are also reported on the secondary effects of relevant variables such as temperature or shear rate(or frequency)on the dependence of crystallinity on viscosity.As for the effect of temperature,Titomanlio[15]found for an iPP that the increase of viscosity for the same crystallinity degree was higher at lower temperatures,whereas Winter[63] reports the opposite trend for a thermoplastic elasto-meric polypropylene.As for the effect of shear rate,a general agreement is found in the literature that the increase of viscosity for the same crystallinity degree is lower at higher deformation rates[62,61,57].Essentially,the equations adopted to describe the effect of crystallinity on viscosity of polymers can be grouped into two main categories:–equations based on suspensions theories(for a review,see[64]or[65]);–empirical equations.Some of the equations adopted in the literature with regard to polymer processing are summarized in Table1.Apart from Eq.(17)adopted by Katayama and Yoon [66],all equations predict a sharp increase of viscosity on increasing crystallinity,sometimes reaching infinite (Eqs.(18)and(21)).All authors consider that the relevant variable is the volume occupied by crystalline entities(i.e.x),even if the dimensions of the crystals should reasonably have an effect.1.1.5.Modeling of the molecular orientationOne of the most challenging problems to present day polymer science regards the reliable prediction of molecular orientation during transformation processes. Indeed,although pressure and velocity distribution during injection molding can be satisfactorily described by viscous models,details of the viscoelastic nature of the polymer need to be accounted for in the descriptionTable1List of the most used equations to describe the effect of crystallinity on viscosityEquation Author Derivation Parameters h=h0Z1C a0x(17)Katayama[66]Suspensions a Z99h=h0Z1=ðx K x cÞa0(18)Ziabicki[67]Empirical x c Z0.1h=h0Z1C a1expðK a2=x a3Þ(19)Titomanlio[15],also adopted byGuo[68]and Hieber[25]Empiricalh=h0Z expða1x a2Þ(20)Shimizu[69],also adopted byZuidema[22]and Hieber[25]Empiricalh=h0Z1Cðx=a1Þa2=ð1Kðx=a1Þa2Þ(21)Tanner[70]Empirical,basedon suspensionsa1Z0.44for compact crystallitesa1Z0.68for spherical crystallitesh=h0Z expða1x C a2x2Þ(22)Han[36]Empiricalh=h0Z1C a1x C a2x2(23)Tanner[71]Empirical a1Z0.54,a2Z4,x!0.4h=h0Zð1K x=a0ÞK2(24)Metzner[65],also adopted byTanner[70]Suspensions a Z0.68for smooth spheresR.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221193。
聚丙烯挤出成型实验报告(3篇)

第1篇一、实验目的本次实验旨在了解聚丙烯(PP)材料的挤出成型工艺,掌握挤出成型的基本原理和操作方法,并通过对实验结果的分析,探讨影响挤出成型质量的因素。
二、实验原理聚丙烯是一种热塑性树脂,具有良好的力学性能、耐化学性和耐热性。
挤出成型是聚丙烯材料常用的成型方法之一,通过挤出机将熔融的聚丙烯树脂经过模具成型,得到所需的塑料制品。
三、实验材料与设备1. 实验材料:聚丙烯(PP)颗粒2. 实验设备:- 聚丙烯挤出机- 温控装置- 模具- 冷却水循环系统- 切割机- 电子天平- 光学显微镜四、实验步骤1. 准备工作- 将聚丙烯颗粒过筛,去除杂质。
- 将挤出机预热至设定温度。
2. 原料塑化- 将过筛的聚丙烯颗粒加入挤出机料斗。
- 启动挤出机,使聚丙烯颗粒在挤出机内塑化熔融。
3. 挤出成型- 调整模具,使其符合所需产品的形状和尺寸。
- 控制挤出机的转速和温度,使熔融的聚丙烯树脂通过模具成型。
4. 冷却和切割- 将成型后的产品通过冷却水循环系统冷却至室温。
- 使用切割机将冷却后的产品切割成所需长度。
5. 检验- 使用电子天平称量产品的重量,检查其尺寸精度。
- 使用光学显微镜观察产品的表面和断面,检查其外观和内部结构。
五、实验结果与分析1. 产品外观- 产品表面光滑,无气泡、裂纹等缺陷。
2. 产品尺寸- 产品尺寸符合设计要求,尺寸精度较高。
3. 产品内部结构- 产品内部结构均匀,无分层、杂质等缺陷。
4. 影响因素分析- 温度:温度对挤出成型质量有较大影响。
过高或过低的温度都会导致产品出现缺陷。
实验中发现,当温度过高时,产品易出现熔融流淌;温度过低时,产品易出现结晶不良。
- 转速:转速对产品的尺寸和外观有较大影响。
转速过高或过低都会导致产品出现尺寸偏差和表面缺陷。
- 模具:模具的形状和尺寸对产品的形状和尺寸有直接影响。
模具设计不合理会导致产品出现尺寸偏差和表面缺陷。
六、实验结论本次实验成功地进行了聚丙烯挤出成型,得到了符合设计要求的产品。
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在工业上和实验室中,螺杆挤出机都应用及其普遍,是塑料加工设备的重要元部件之一。
作为工业中使用的双螺杆挤出机,在设计过程中,除了要求能够完成固体输送、增压、熔融、熔体输送和泵压等一系列通用过程以外,还要求涉及到复合塑料与聚合物颗粒之间的混合,以及物料喂料量的控制。
物料喂料量的控制则是通过控制主螺杆及其辅助喂料螺杆的转速来完成的。
同时,双螺杆挤出机具有分布混合和分散混合效果良好、自洁作用较强、可实现高速运转、产量高等特点,特别适合聚合物的改性,如共混、填料、增强及反应挤出。
有利于增加挤出机的挤出产量,提高塑化质量。
关键词:双螺杆挤出机;辅助喂料螺杆;工业;同向啮合23目录1、绪论 (1)1.1 塑料挤出成型概述 (1)1.2塑料挤出成型的基本特点 (1)1.3塑料挤出成型设备的组成 (1)1.4 挤出机的分类 (2)1.5 挤出机的选择原则和方法 (3)1.6 挤出螺杆的选择 (3)2、同向啮合双螺杆挤出机 (4)2.1 挤出机型号说明 (4)2.2 挤出成型基本原理 (4)2.3 同向啮合双螺杆挤出机工作原理及其特性 (6)2.4本次所设计挤出机类型的确定 (6)2.5 同向啮合双螺杆挤出机的主要技术参数和规格 (6)3、同向啮合双螺杆挤出机性能参数的选择 (7)3.1螺杆直径的选择 (7)3.2螺杆中心距公称尺寸的选择 (7)3.3螺杆长径比的选择 (7)3.4螺杆转速要求及范围的选择 (8)3.5 挤出机功率的确定 (8)3.6挤出机加热功率的确定 (8)4、同向啮合双螺杆挤出机主要零部件的设计 (8)4.1 主螺杆的设计 (9)4.2机筒的设计 (10)4.3 螺杆与机筒的配合要求 (11)4.4分流板及过滤网 (11)4.5料斗的设计 (11)5 挤出机电机的选择 (12)6 减速器的设计 (12)6.1 传动方案的总体设计 (12)6.2齿轮设计 (12)6.3 齿轮轴的设计 (22)6.6 箱体的设计 (34)结束语 (36)1参考文献 (37)致谢 (37)21、绪论1.1 塑料挤出成型概述挤出成型是在挤出机中通过加热、加压使各种塑料以熔融流动状态连续通过口模成型的方法。
当今世界四大材料体系(木材、硅酸盐、金属和聚合物)中,聚合物和金属是应用最广泛和最重要的两种材料。
其中不仅包括板、管、膜、丝、和型材等制品的直接成型,还包括热成型、中空吹塑等坯料的挤出加工。
挤出机几乎成为任何一个塑料有关公司或研究所最基本的装备之一。
挤出成型有如此发展趋势主要原因为:螺杆挤出机能将一系列化工基本单元过程,如固体输送、增压、熔融、排气、脱湿、熔体输送和泵出等物理过程集中在挤出机内的螺杆上来进行。
螺杆挤出工艺装备逐步取代了一些由多台经典化工装备组成的生产线。
连续生产代替间歇生产,必然有较高的生产率和较低的能耗,减少生产面积和操作人员数量,降低生产成本,也易于实现生产自动化,创造好的劳动条件和减少的环境污染。
正因如此,螺杆挤出这种工艺不仅广泛地用于聚合物加工,而且在建材、食品、纺织、军工、和造纸等工业部门中都得到了愈来愈多的应用。
1.2塑料挤出成型的基本特点与其他成型方法比较,挤出成型具有以下的特点:(1)挤出成型可实现生产的连续化和自动化。
生产操作简单,工艺控制容易,效率高,产品质量稳定。
(2)可以根据产品的不同要求,改变产品的断面形状。
其产品为管材、薄膜、电缆、单丝、棒材、板材、片材、中空制品及异型材等。
(3)连续的生产操作,特别适合于较长尺寸的制(4)应用范围广泛。
如可以加工大多数热塑性塑料及部分热固性塑料,用挤出法进行共混改性、塑化、造粒、脱水和着色等。
(5)设备成本低、投资少、见效快,生产占地面积小,生产环境清洁。
(6)可进行综合性生产。
伴随着塑料工业的迅猛发展,还将具有更广阔的应用前景。
1.3塑料挤出成型设备的组成一套完整的挤出设备由主机、辅机及控制系统组成。
1.3.1 主机挤出机是塑料挤出成型的主要设备,即主机。
由挤压系统、传动系统及加热冷却系统和主机控制系统组成。
①挤压系统由机筒、螺杆和料斗组成,是挤出机的核心工作部分。
②传动系统由电机、调速装置和传动装置组成。
作用是给螺杆提供所需转速和扭矩。
③加热冷却系统由温控设备组成。
作用是通过对机筒进行加热和冷却,以保证挤出系统成型在工艺要求的温度范围内进行。
④控制系统主要由仪表、电器及执行机构组成。
作用是调节控制机筒温度、机头压力和螺杆转速。
1.3.2辅机通常包括:机头、冷却系统、定型装置、牵引装置、切割装置和卷曲装置等。
①机头是制品成型的主要部件,熔融塑料通过机头获得断面与流道几何形状相似的塑料制品。
②定型装置作用是将机头中挤出的制品的形状稳定下来,并对其进行精确调整,从而得获得断面尺寸精确且表面光滑的塑料制品。
③冷却装置从定型装置出来的制品冷却,获得最终的形状和尺寸。
④牵引装置作用是均匀的牵引制品,使挤出过程稳定。
⑤切割装置作用是将挤出的连续硬制品切成所需长度及宽度。
⑥卷取装备作用是将软制品(薄膜、单丝等)卷绕成卷。
1.3.3 控制系统由各种电器、仪表及执行机构组成。
根据自动化水平的高低,可控制挤出机、辅机的拖动电机、油(汽)缸、驱动油泵及其他各种执行机构按所需的速度、功率和轨迹运行监控主辅机的流量、温度及压力,最终实现对整个挤出成型设备的自动控制和对产品质量的控制。