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橡胶片材挤出机 橡胶片材机
橡胶片材挤出成型定义
在纤维化学工业中也有用挤出机向喷丝头供料，以进行熔体纺丝。挤出应用于热塑性塑料和橡胶的加工，可进行配料、造粒、胶料过滤等，可连续化生产，制造各种连续制品如板材(或片材)、薄膜、电线电缆包覆、橡胶轮胎胎面条、内胎胎筒、密封条等，其生产效率高。在合成树脂生产中，挤出机可作为反应器，连续完成聚合和成型加工,在橡胶工业中压缩比不同的挤出机可以用来塑炼天然胶.不同材料的挤出机器的压缩比有些不同.
橡胶片材挤出成型原理
料自料斗进入料筒，在螺杆旋转作用下，通过料筒内壁和螺杆表面摩擦剪切作用向前输送到加料段，在此松散固体向前输送同时被压实；在压缩段，螺槽深度变浅，进一步压实，同时在料筒外加热和螺杆与料筒内壁摩擦剪切作用，料温升高开始熔融，压缩段结束；均化段使物料均匀，定温、定量、定压挤出熔体，到机头后成型，经定型得到制品。
１、挤出方法
按塑化方式：干法挤出与湿法挤出
按加压方式：连续挤出与间歇挤出
2、特点
生产连续、效率高、操作简单、应用范围广
挤出成型设备
1、主机
挤出系统：由螺杆与料筒组成，是挤出机关键部分。其作用是塑化物料，定量、定压、定温挤出熔体
传动系统：驱动螺杆，提高所需的纽矩和转矩
加热和冷却系统：保证塑料和挤出系统在成型过程中温度达工艺要求
2、辅机
由机头、定型装置、冷却装置、牵引装置、卷取装置、切割组成
3、控制系统
由电器、仪表和执行机构组成
作用：控制主、辅机电动机、以满足所需转速和功率；控制主辅机温度、压力、流量，保证制品质量；实现挤出机组的自动控制，保证主、辅机协调运行。
橡胶片材挤出机的概述
橡胶片材挤出机的主机是橡胶片材机，它由挤压系统、传动系统和加热冷却系统组成。
1.挤压系统 挤压系统包括螺杆、机筒、料斗、机头、和模具，塑料通过挤压系统而塑化成均匀的熔体，并在这一过程中所建立压力下，被螺杆连续的挤出机头。
（1） 螺杆：是橡胶片材机的最主要部件，它直接关系到橡胶片材机的应用范围和生产率，由高强度耐腐蚀的合金钢制成。
（2）机筒：是一金属圆筒，一般用耐热、耐压强度较高、坚固耐磨、耐腐蚀的合金钢或内衬合金钢的复合钢管制成。机筒与螺杆配合，实现对塑料的粉碎、软化、熔融、塑化、排气和压实，并向成型系统连续均匀输送胶料。一般机筒的长度为其直径的15～30 倍，以使塑料得到充分加热和充分塑化为原则。
（3） 料斗：料斗底部装有截断装置，以便调整和切断料流，料斗的侧面装有视孔和标定计量装置。
（4）机头和模具：机头由合金钢内套和碳素钢外套构成，机头内装有成型模具。机头的作用是将旋转运动的塑料熔体转变为平行直线运动，均匀平稳的导入模套中，并赋予塑料以必要的成型压力。塑料在机筒内塑化压实，经多孔滤板沿一定的流道通过机头脖颈流入机头成型模具，模芯模套适当配合，形成截面不断减小的环形空隙，使塑料熔体在芯线的周围形成连续密实的管状包覆层。为保证机头内塑料流道合理，消除积存塑料的死角，往往安置有分流套筒，为消除塑料挤出时压力波动，也有设置均压环的。机头上还装有模具校正和调整的装置，便于调整和校正模芯和模套的同心度。
橡胶片材机按照机头料流方向和螺杆中心线的夹角，将机头分成斜角机头（夹角120o）和直角机头。机头的外壳是用螺栓固定在机身上，机头内的模具有模芯坐，并用螺帽固定在机头进线端口，模芯座的前面装有模芯，模芯及模芯座的中心有孔，用于通过芯线；在机头前部装有均压环，用于均衡压力；挤包成型部分由模套座和模套组成，模套的位置可由螺栓通过支撑来调节，以调整模套对模芯的相对位置，便于调节挤包层厚度的均匀性。机头外部装有加热装置和测温装置。
2.传动系统 传动系统的作用是驱动螺杆，供给螺杆在挤出过程中所需要的力矩和转速，通常由电动机、减速器和轴承等组成。
3.加热冷却装置 加热与冷却是塑料挤出过程能够进行的必要条件。
（1） 现在橡胶片材机通常用的是电加热，分为电阻加热和感应加热，加热片装于机身、机脖、机头各部分。加热装置由外部加热筒内的塑料，使之升温，以达到工艺操作所需要的温度。
（2）冷却装置是为了保证塑料处于工艺要求的温度范围而设置的。具体说是为了排除螺杆旋转的剪切摩擦产生的多余热量，以避免温度过高使塑料分解、焦烧或定型困难。机筒冷却分为水冷与风冷两种，一般中小型橡胶片材机采用风冷比较合适，大型则多采用水冷或两种形式结合冷却；螺杆冷却主要采用中心水冷，目的是增加物料固体输送率，稳定出胶量，同时提高产品质量；但在料斗处的冷却，一是为了加强对固体物料的输送作用，防止因升温使塑料粒发粘堵塞料口，二是保证传动部分正常工作。
二、 辅助设备
橡胶片材挤出机组的辅机主要包括放线装置、校直装置、预热装置、冷却装置、牵引装置、计米器、火花试验机、收线装置。挤出机组的用途不同其选配用的辅助设备也不尽相同。如还有切断器、吹干器、印字装置等。
校直装置：塑料挤出废品类型中最常见的一种是偏心，而线芯各种型式的弯曲则是产生绝缘偏心的重要原因之一。在护套挤出中，护套表面的刮伤也往往是由缆芯的弯曲造成的。因此，各种橡胶片材机组中的校直装置是必不可少。校直装置的主要型式有：滚筒式（分为水平式和垂直式）；滑轮式（分为单滑轮和滑轮组）；绞轮式，兼起拖动、校直、稳定张力等多种作用；压轮式（分为水平式和垂直式）等。
预热装置：缆芯预热对于绝缘挤出和护套挤出都是必要的。对于绝缘层，尤其是薄层绝缘，不能允许气孔的存在，线芯在挤包前通过高温预热可以彻底清除表面的水份、油污。对于护套挤出来讲，其主要作用在于烘干缆芯，防止由于潮气（或绕包垫层的湿气）的作用使护套中出现气孔的可能。预热还可防止挤出中塑料因骤冷而残留内压力的作用。在挤塑料过程中，预热可消除冷线进入高温机头，在模口处与塑胶接触时形成的悬殊温差，避免塑胶温度的波动而导致挤出压力的波动，从而稳定挤出量，保证挤出质量。橡胶片材机组中均采用电加热线芯预热装置，要求有足够的容量并保证升温迅速，使线芯预热和缆芯烘干效率高。预热温度受放线速度的制约，一般与机头温度相仿即可。
冷却装置：成型的塑料挤包层在离开机头后，应立即进行冷却定型，否则会在重力的作用下发生变形。冷却的方式通常采用水冷却，并根据水温不同，分为急冷和缓冷。急冷就是冷水直接冷却，急冷对塑料挤包层定型有利，但对结晶高聚物而言，因骤热冷却，易在挤包层组织内部残留内应力，导致使用过程中产生龟裂，一般 PVC塑胶层采用急冷。缓冷则是为了减少制品的内应力，在冷却水槽中分段放置不同温度的水，使制品逐渐降温定型，对PE、PP的挤出就采用缓冷进行，即经过热水、温水、冷水三段冷却。
三、 控制系统
橡胶片材挤出机的控制系统包括加热系统、冷却系统及工艺参数测量系统，主要由电器、仪表和执行机构（即控制屏和操作台）组成。其主要作用是：控制和调节主辅机的拖动电机，输出符合工艺要求的转速和功率，并能使主辅机协调工作；检测和调节橡胶片材机中塑料的温度、压力、流量；实现对整个机组的控制或自动控制。
挤出机组的电气控制大致分为传动控制和温度控制两大部分，实现对挤塑工艺包括温度、压力、螺杆转数、螺杆冷却、机筒冷却、制品冷却和外径的控制，以及牵引速度、整齐排线和保证收线盘上从空盘到满盘的恒张力收线控制。
1. 橡胶片材机主机的温度控制
电线电缆绝缘和护套的塑料挤出是根据热塑性塑料变形特性，使之处于粘流态进行的。除了要求螺杆和机筒外部加热，传到塑料使之融化挤出，还要考虑螺杆挤出塑料时其本身的发热，因此要求主机的温度应从整体来考虑，既要考虑加热器加热的开与关，又要考虑螺杆的挤出热量外溢的因素予以冷却，要有有效的冷却设施。并要求正确合理的确定测量元件热电偶的位置和安装方法，能从控温仪表读数准确反映主机各段的实际温度。以及要求温控仪表的精度与系统配合好，使整个主机温度控制系统的波动稳定度达到各种塑料的挤出温度的要求。
2. 橡胶片材机的压力控制
为了反映机头的挤出情况，需要检测挤出时的机头压力，由于国产橡胶片材机没有机头压力传感器，一般是对螺杆挤出后推力的测量替代机头压力的测量，螺杆负荷表（电流表或电压表）能正确反映挤出压力的大小。挤出压力的波动，也是引起挤出质量不稳的重要因素之一，挤出压力的波动与挤出温度、冷却装置的使用，连续运转时间的长短等因素密切相关。当发生异常现象时，能排除的迅速排除，必须重新组织生产的则应果断停机，不但可以避免废品的增多，更能预防事故的发生。通过检测的压力表读数，就可以知道塑料在挤出时的压力状态，一般取后推力极限值报警控制。
3. 螺杆转速的控制
螺杆转速的调节与稳定是主机传动的重要工艺要求之一。螺杆转速直接决定出胶量和挤出速度，正常生产总希望尽可能实现最高转速及实现高产，对橡胶片材机要求螺杆转速从起动到所需工作转速时，可供使用的调速范围要大。而且对转速的稳定性要求高，因为转速的波动将导致挤出量的波动，影响挤出质量，所以在牵引线速度没有变化情况下，就会造成线缆外径的变化。同理如牵引装置线速波动大也会造成线缆外径的变化，螺杆和牵引线速度可通过操作台上相应仪表反映出来，挤出时应密切观察，确保优质高产。
4. 外径的控制
如上所述为了保证制品线缆外径的尺寸，除要求控制线芯（缆芯）的尺寸公差外，在挤出温度、螺杆转速、牵引装置线速度等方面应有所控制保证，而外径的测量控制则综合反映上述控制的精度和水平。在橡胶片材机组设备中，特别是高速挤塑生产线上，应配用在线外径检测仪，随时对线缆外径进行检测，并且将超差信号反馈以调整牵引或螺杆的转速，纠正外径超差。
5. 收卷要求的张力控制
为了保证不同线速下的收线，从空盘到满盘工作的恒张力要求，希望收排线装置有贮线张力调整机构，或在电气上考虑恒线速度系统和恒张力系统的收卷等等。
6. 整机的电气自动化控制
这是实现高速挤出生产线应具备的工艺控制要求，主要是：开机温度联锁；工作压力保护与联锁；挤出、牵引两大部件传动的比例同步控制；收线与牵引的同步控制；外径在线检测与反馈控制；根据各种不同需要组成部件的单机与整机跟踪的控制。
挤出机分类
按数量分：无螺杆、单螺杆、双螺杆
按空间位置：卧式和立式
按螺杆转速：普通、高速和超高速
可否排气：排气式和非排气式
按装配结构：整体式和分开式
最常用卧式单螺杆非排气式整体式挤出机
挤出机的主要零部件
一、螺杆
1、评价螺杆性能的标准和设计螺杆应考虑的因素
1）评价螺杆性能标准
①塑化质量：必须满足质量要求。制品质量与机头、辅机有关，但与螺杆的塑化质量关系更大，如温度不均、轴向压力波动、径向温度大、染色等分散不均匀，这都直接影响制品质量。
②产量：在保证质量前提下，通过机头挤出量。好的螺杆，应具有高的塑化能力
③名义比功率单耗：每挤1Kg塑料消耗的产量即P/Q（功率/产量），保证质量下，单耗越少越好。
④适应性：对加工不同塑料、匹配不同机头和不同制品的适应能力。但一般适应性强，往往塑化效率低。
⑤制造难易：必须易制造、成本低
2）设计螺杆应考虑
①物料特性及加工时的几何形状、尺寸、温度状况。由于不同物料物理特性不同，因此加工性能不同，对螺杆结构和几何参数有不同要求。
②口模的几何形式和机头阻力特性。螺杆形状要与他们相匹配。
料筒的结构形式和加热冷却情况。如在加料段料筒内壁加工出锥度和纵向沟槽并冷却，则提高固体输送效率，螺杆在设计时应考虑提高熔融速率、均化能力，使之与加料段输送相匹配。
③螺杆转速
④挤出机用途：作混炼、造粒和喂料等作用，螺杆结构有所不同
2、常规全螺纹三段螺杆设计
指螺杆由加料段、压缩段、均化段三段螺纹组成，其挤出过程完全依靠螺纹的形式来完成的一种螺杆。
1）螺杆类型确定
按螺槽深度从加料段较深向均化段较浅的过渡情况分：
①渐变型：螺槽深度变化在较长距离逐渐变浅。用于无定型、热敏性塑料加工、也可用结晶型。
②突变型：用于熔点突变、粘度低的塑料。如PA、PE、PP，不适于PVC等热敏性塑料
2）螺杆直径
已经标准化，其大小一般根据所加工制品的断面尺寸、加工塑料种类、所需挤出量确定
3）螺杆长径比L/Db
长径比越大，则塑料在料筒中停留时间越长，塑化更充分、均匀，以保证制品质
单螺杆挤出机技术参数和型号
1、单螺杆挤出机技术参数
螺杆直径Db：指大径，系列标准20、30、45、65、90、120、150、165、200、250、300
螺杆长径比L/Db：螺杆工作部分长度与螺杆直径比值
螺杆转速范围：nmin-nmax r/min
驱动螺杆电机功率P：KW
挤出机生产能力Q：每小时挤出的塑料量
比流量每小时每转一周挤出机生产能力
名义比功率 每小时加工kg塑料所需电机功率
2、型号
SL-150表示螺杆直径为150mm，长径比为20：1塑料挤出
挤出工艺参数
1、温度
挤出成型温度有料筒温度、塑料温度、螺杆温度，一般我们测料筒温度。温度由加热冷却系统控制，由于螺杆结构、加热冷却系统不稳定、螺杆转速变化等原因使挤出物料温度在径向和轴向都存在波动，从而影响制品质量，制品各点强度不一样，产生残余应力，表面灰暗无光泽。为保证制品质量，温度应稳定。
2、压力
由于螺杆和料筒结构，机头、过滤网、过滤板的阻力，使塑料内部存在压力。压力变化如图，压力同样存在波动。
3、挤出速率
单位时间内由挤出机口模挤出的塑料质量或长度。影响挤出速率因素：机头阻力、螺杆与料筒结构、螺杆转速、加热、冷却系统、塑料特性。但当产品已定，挤出速率仅与螺杆转速有关。挤出速率也存在波动，影响制品几何形状和尺寸。
温度、压力、挤出速率都存在波动现象，为了保证制品质量，应正确设计螺杆、控制好加热冷却系统和螺杆转速稳定性，以减少参数波动。
挤出成型工艺
一般根据所加工聚合物的类型和制品或半成品的形状，选定挤出机、机头和口模，以及定型和牵引等相应的辅助装置，然后确定挤出工艺条件如螺杆转速、机头压力、物料温度，以及定型温度、牵引速度等。在挤出过程中，物料一般都要经过塑炼，但定型方法则有所不同。例如，挤出的塑料常需冷却定型，使其固化，而挤出橡胶的半成品，则尚需进一步硫化。采用不同的挤出设备和工艺，可得到不同的制品。
粒料
聚合物与各种添加剂混合后，送入挤出机中熔化，并进一步混合均匀。通过多孔口模，形成多根条料，再切断成粒料。切断有热切粒和冷切粒之分。前者条料离口模后，一边用空气或水冷却，一边立即用旋转刀切断。后者是将条料全部冷却后，再送入切粒机切粒。
片材和薄膜
凡厚度在0.25mm以上，长度比宽度大很多的扁平制品称片材；厚度小于0.25mm者称薄膜。如将扁平口模出来的膜状物，通过一表面十分光洁的冷却转鼓冷却定型,即可制得平膜,此法也称挤出流延法。这是制造聚丙烯薄膜常用方法。如果将所得平膜送入拉幅机，在纵向及横向同时拉伸 4～10倍（也可先纵向拉伸，再横向拉伸）,则可制得双轴定向薄膜。由于拉伸时,大分子取向，因此薄膜强度很高，但透水、透气性有所降低。常用于制造聚丙烯和聚酯薄膜。如物料内加发泡剂，并采用特殊螺杆和口模，也可制得低发泡沫塑料板材。
包覆线
当金属裸线通过一个 T形口模时，熔融塑料即围绕裸线而形成包覆层（图3[包覆线用机头]）,包覆线被冷却卷绕后，即得各种电线电缆制品。
管材挤出工艺
设备：挤出机、机头、定型装置、冷却槽、牵引设备和切割设备
1、成型
由挤出模具实现。熔体经过滤网和过滤板，分流区、压缩区、成型区而成为管状物。
2、定型
方法：内径定径与外径定径（内压法与真空法）
3、管材挤出工艺条件控制
温度：料筒、机头和口模温度，是影响塑化和制品质量的主要因素。挤出管材温度一般较低，粘度高，有利于定型。
挤出速率：影响产量和质量，其值决定于螺杆转速
牵引速度：影响管材壁厚和直径的的精确性，要与挤出速度相适应。
压缩空气压力：内压法压力0.02~0.05MPa
吹塑薄膜法成型工艺
1、挤出与吹胀
设备：挤出机及机头、冷却装置、夹板、牵引辊、导向辊、卷取装置。
2、吹塑薄膜挤出工艺条件
温度：料筒、机头和机颈温度。温度过高，薄膜发脆，抗拉强度下降；过高，抗拉强度低、表面光泽差、透明度下降、有熔接痕。
吹胀比与牵伸比：吹胀比—管膜直径与口模之比（2-3）；牵伸比—薄膜伸长倍数（4-6）。
冷却速度：由冷却装置调节。冷冻线—吹胀管膜上已冷却定型的线；冷冻线越远，冷却速度越慢，薄膜横向易撕裂。
挤出成型工艺应用
采用几台挤出机,同时供应几种塑料,再通过共用机头挤出，形成一个整体的复合制品。例如用A、B、C三种塑料共挤出，可生产各种复合薄膜、复合片材、板材、型材和管材。
胶料过滤
在制造薄壁橡胶制品时，为了防止制品发生漏气、漏水，胶料不能含有杂质，一般在加入硫化剂前用挤出机过滤胶料，即在机头处放置一层或多层滤网，以滤去塑化物料中杂质。
轮胎胎面和内胎制造 胎面分整体挤出和分层挤出。整体挤出可用一台挤出机将一种胶料经扁平口模挤出；也可用两种胶料（胎冠料和胎侧料）两台挤出机共挤出，在共挤出机头内结合成一个整体胎面。分层挤出则用两台挤出机分别将两种胶料挤成胎冠和胎侧，再在运输带上进行热贴合，并经多圆盘活络辊压为整体。内胎挤出和管子挤出相似，胎筒挤成后，经切断，再接头成型。
熔体纺丝
一些粘度大的树脂在熔体纺丝时，常用挤出机来熔融物料。熔好的物料直接经过过滤器进入喷丝头，或用喷丝泵打入喷丝头
Rubber sheet extrusion molding definition
In chemical fiber industry are also useful to the spinneret material feeding extruder, to melt spinning. Extrusion is applied to the thermoplastic plastic and rubber processing, can be carried out ingredients, granulation, rubber filtration, etc., can be continuous production, and manufacturing for all kinds of products such as plate (or sheet), thin film, wire and cable, coating, rubber tire noodles, inner tube, tire tube, seals, etc., the production efficiency is high. In synthetic resin production, extruder as reactor, continuous polymerization and forming, different compression ratio in the rubber industry of plastic extruding machine can be used to refined natural rubber. Extrusion machine somewhat different compression ratio of different materials.
Rubber sheet extrusion molding principle
Since the hopper into the cylinder, under the effect of screw rotation, through the inner wall of the cylinder and the screw surface friction shearing action forward to feeding section, the loose solid conveying forward by compaction; at the same time In the compression section, spiral groove depth becomes shallow, further compaction, at the same time in cylinder plus heat and screw with a nitrogen-treated barrel wall friction shearing action, high temperature began to melt, period is over; Homogenization section materials uniform, constant temperature, quantitative and constant pressure extruding melt, after the head forming, the finalize the design product.
1, the extrusion method
By way of plasticizing: dry and wet extrusion came out
According to pressure mode: continuous extrusion and intermittent extrusion
2, the characteristics of
The production of continuous, high efficiency, simple operation, wide application range
Extrusion molding equipment
1, host,
Extrusion system: consists of a screw with a nitrogen-treated barrel, is a key part of extruder. Role is its plasticizing materials, quantitative and constant pressure, constant temperature extrusion melt
Transmission system: drive screw, improve the new torque and torque required
Heating and cooling system: ensure that the plastic and extrusion system in the process of forming temperature of technological requirements
2, auxiliary engine
By the nose, finalize the design equipment, cooling device, traction device, take-up device, cutting
3, the control system
Consists of electrical appliances, instruments and actuators
Function: main, auxiliary engine motor control, to meet the required speed and power; Control the main auxiliary engine temperature, pressure, flow, ensure the quality of products; Realize automatic control of extrusion unit, ensure main, auxiliary engine coordination operation.
An overview of the rubber sheet extruder
Rubber sheet extruder host is rubber sheet machine, it is composed of extrusion system, transmission system and heating cooling system.
1. Squeezing extrusion system, including screw, barrel, hopper, the nose, and mould, plastic plastic into homogeneous melt by extrusion system, and established in the process, under pressure by the screw continuous extrusion head.
Screw (1) : is the main component of the rubber sheet machine, it is directly related to the application range of the rubber sheet machine and productivity, is made from high strength and corrosion resistance of alloy steel.
(2) the barrel: is a metal cylinder, generally with heat resistant, high crushing strength, strong wear resistance, corrosion resistance of alloy steel or lining made of alloy steel composite pipe. Barrel and screw, implementation of plastic crushing, softening and melting and plasticizing, exhaust and compaction, and to the continuous uniform conveying rubber molding system. General barrel length is the diameter of 15 ~ 30 times, in order to make fully heating and fully plastic into a principle.
(3) the hopper: at the bottom of the hopper is equipped with cutting device, in order to adjust and stop the flow of material, the side of the hopper is equipped with sight hole measuring device and calibration.
And mould (4) the nose: the nose consists of alloy steel inner sleeve and carbon steel jacket, inside the nose with molding. Is the role of head rotation movement of the plastic melt into a parallel straight line, import the die set is steady, and give necessary to plastic molding pressure. Plastic plasticizing compaction in the barrel, is approved by the flow of porous filter plate along a certain head neck into the head forming die, die core die set appropriate coordination, the formation of cross section and decreases the annular space, make the plastic melt around the conductor to form a continuous solid tubular cladding layer. In order to ensure the nose in plastic flow is reasonable, eliminate accumulated plastic corner, placed tend to have a split sleeve, to eliminate the plastics extrusion pressure fluctuations, also has a set of equalizing ring. The nose is also equipped with mold correction and adjustment device, easy adjustment and correction of mold core and mold set of concentricity.
Rubber sheet machine according to the head material flow direction and the Angle of the center line of the screw, will head into bevel head Angle of 120 o and crosshead. The nose of the shell is bolted on the fuselage, the mold has a mold core inside the head, with a nut fixed in the nose into the line port, the front of the mold core cities with mold core, mold core and mold core of the center hole, used by conductor; In the front of the nose with equalizing ring for balanced pressure; Extrusion molding package part is composed of die sleeve and die set, the location of the die set can be made of bolt support to adjust, to adjust the die set of the relative position of mold core, easy to adjust the uniformity of extrusion cladding thickness. Starting from an external is equipped with heating device and temperature measuring device.
2. The role of the transmission system transmission system is a screw driver, and supply the screw in the required torque and rotational speed in the process, usually composed of motor, reducer and bearing, etc.
3. The heating cooling device heating and cooling is necessary for plastics extrusion process can be.
(1) rubber sheet machine is commonly used now is electric heating, divided into resistance heating and induction heating, heating tablets in the fuselage, machine neck, in all parts of the nose. Heating device by the plastic inside the external heating tube, heating, in order to achieve the temperature of the process operation need.
(2) the cooling device is to ensure that the plastic in the temperature range of technical requirement. Specifically to rule out the screw rotating the excess heat generated by the shear friction, in order to avoid high temperature make plastic decomposition, charred or difficult to finalize the design. Barrel cooling into the water and air cooling two, general small and medium-sized rubber sheet machine adopts air cooling is more appropriate, large use water more or two forms combined with cooling; Screw water cooled mainly adopts center, the purpose is to increase the rate of solid conveying material, the quantity of adhesive stability, improve the quality of products at the same time; But the cooling in the hopper, one is to strengthen the transport of solid materials, prevent make jam the material plastic grains sticky with heating, 2 it is to guarantee the normal work of the transmission parts.
Second, the auxiliary equipment
Rubber sheet extrusion unit auxiliary machine mainly includes pay-off device, straightening device, preheating device, cooling device, traction device, the meter machine, sparks machine, take-up device. Extrusion unit USES its matching with different auxiliary equipment are also different. If there are cutter, blow dry device, printing equipment, etc.
Straightening device: plastic extruding waste is one of the most common eccentric type, and various types of bending line core is one of the important reasons for the insulation eccentricity. In sheathed extrusion, scratches on the surface of the sheath tend to be caused by a cable bending. Therefore, all kinds of rubber sheet unit in the straightening device is essential. Straightening device of the main types are: drum (divided into horizontal and vertical); Pulley (divided into single block and block and tackle); Ground wheel, and a variety of action such as drag, straightening and stable tension; Pressure wheel (divided into horizontal and vertical), etc.
Preheating device: preheat for insulation extrusion and cable core sheathed extrusion is necessary. For insulation, especially the thin layer of insulation, can not allow the existence of the porosity, wire core before extruded through high temperature preheating can completely remove the surface of the water and oil. For sheathed extrusion, the main function is to dry the cable core, prevent the moisture (or winding and the moisture content in the cushion layer) role in the sheath may appear porosity. Preheating can also prevent extrusion plastic due to quenching residual stress in the role. In the process of extrusion plastic, preheating can eliminate cold line into the nose by high temperature, in gate in contact with the plastic forming of wide temperature difference, avoid plastic temperature fluctuations caused by extrusion pressure fluctuations, thus stable extrusion quantity, ensure the quality of extrusion. Rubber sheet in the unit adopts electric hotline core preheating device, have enough capacity required and ensure warming rapidly, make the line core preheating and core drying efficiency is high. The restriction of the feeding speed, preheat temperature is similar with the nose temperature.
Cooling device: molding of plastic extrusion cladding after leaving the nose should be performed immediately after heating, otherwise it will occur deformation under the effect of gravity. Usually adopts water cooling, cooling way and according to the water temperature is different, divided into mild cold. Quenching is cold water cooling, direct quenching is good for plastic extrusion cladding to finalize the design, but for crystal polymer, because of the sudden heat cooling, easy in extrusion cladding organization internal residual stress, leading to cracks in the course of using, general PVC plastic layer by rapid cooling. Slow cooling is to reduce the internal stress of products, block placed different temperature of the water in the cooling water tank, cooling the products gradually to finalize the design, extrusion of PE, PP, with a slow cooling which three sections of cooling after hot water, warm water, cold water.
Three, the control system
Rubber sheet extruder control system including the heating system, cooling system and the process parameters measurement system, is mainly composed of electrical appliances, instruments and actuators (i.e., control panel and work station). Its main role is: control and adjustment of the main auxiliary drive motor, the output meet the technological requirements of speed and power, and can make the main auxiliary coordination; To detect and adjust the temperature of the plastic in the rubber sheet machine, pressure, flow rate; Implementation of the entire unit control or automatic control.
Extrusion unit electrical control is roughly divided into drive control and temperature control of two parts, realize the extrusion process including temperature, pressure, screw revolution, cooling, cooling, machine barrel screw products control, cooling and diameter and drawing speed, neat row line and ensure the line plate from the line in empty plate to a plateful of constant tension control.
1. Rubber sheet machine temperature control
Wire and cable insulation and sheath of plastics extrusion is based on the characteristics of thermoplastic deformation make of viscous flow. Except for screw and barrel external heating, to the plastic melt extrusion, but also the screw extrusion plastic itself fever, temperature requirements of the host should consider from overall, therefore, should not only consider the heater heating on and off, and to consider the screw of the factors of cooling the heat, to be effective cooling facilities. And requires correct and reasonable to determine the location of the measuring element thermocouple and installation method, can from the temperature control meter reading to reflect the actual temperature of the host's components. And require the precision of temperature control instrument and system cooperate well, the whole host fluctuations in temperature control system stability reached the requirements of all kinds of plastic extrusion temperature.
2. Rubber sheet machine pressure control
In order to reflect the extrusion of the nose, need to detect the head pressure of extrusion, due to the domestic rubber sheet machine without head pressure sensor, generally is the thrust measurement of screw extrusion head pressure measurements, screw load table (ammeter or a voltmeter) can correctly reflect the size of the extrusion pressure. Extrusion pressure fluctuations, also is one of the important factors of instability caused by extrusion quality, extrusion pressure fluctuations and the use of the extrusion temperature, cooling device, closely related to factors such as the length of the continuous operation time. When abnormal phenomenon occurs, can eliminate quickly ruled out, must reorganize the production should be decisive stop, not only can avoid the waste, can prevent the happening of the accident. By measuring the pressure gauge reading, can know when plastic extrusion stress, generally take after thrust limit alarm control.
3. The screw rotation speed control
The screw rotation speed and stability is the regulation of host drive one of the important technological requirements. The screw rotation speed directly decide the quantity of glue and the speed, the normal production always wanted to achieve the highest rotational speed and achieve high yield as much as possible, requirements for rubber sheet machine screw rotation speed from the starting to the required working speed, speed range that can be used. And demand is high, to the stability of the speed because the rotation speed fluctuations will lead to the fluctuation of impact extrusion quality, so in the case of traction linear speed did not change, can cause the change of the cable diameter. Large fluctuations in the same way as traction device wire speed can cause the change of the cable diameter, screw and traction linear velocity can be reflected on the corresponding instrument, should be closely observed when it is squeezed, ensure good quality and high yield.
4. The diameter control
As mentioned above in order to guarantee the products size of cable diameter, in addition to the required control line core (core) size tolerance, the extrusion temperature, screw speed and traction device linear velocity should be controlled to ensure, and outer diameter measuring control comprehensively reflect the control precision and level. In rubber sheet unit equipment, high speed extrusion production line, in particular, should be with online diameter detector, at any time to test the cable outer diameter, and the error signal feedback to adjust traction or screw speed, out-of-tolerance correct diameter.
5. The requirements of the winding tension control
In order to ensure that under the different wire speed take-up, from empty to plateful job requires constant tension and hope to receive wiring device have storage line tension adjustment mechanism, or consider constant linear velocity and constant tension on electric system of winding and so on.
6. Electrical automation control of the machine
This is to realize the high speed extrusion line should have the process control requirements, mainly: start temperature interlock; Working pressure protection and interlock; Out of the proportion of two parts, traction drive synchronous control; Take-up and traction synchronous control; Outside diameter on-line detection and feedback control; According to the requirements of the various components of the single machine and control the machine track.
Extruder classification
According to the number of points: no screw, single screw, twin-screw
According to the spatial location: horizontal and vertical
According to the screw rotation speed: ordinary, high speed and ultra-high speed
Can exhaust, and the discharge
According to the assembly structure: monolithic and separate type
The most commonly used horizontal single screw not exhaust type integral extruding machine
Main component of the extruder
A, the screw
1, evaluate the performance of screw standards and design factors should be taken into consideration when the screw
1) to evaluate the screw performance standards
Plasticizing quality: (1) must meet the quality requirements. Product quality is related to the nose, auxiliary engine, but with screw bigger plasticizing quality relationship, such as uneven temperature, large axial pressure fluctuation, the radial temperature, dyeing and other scattered unevenly, it directly affects the quality of products.
(2) production: in the guarantee quality premise, through the nose out. A good screw, should have high plasticizing capability
(3) than power consumption: in the name of each with 1 kg plastic production including P/Q (power/output), ensure the quality, consumption, less is more.
(4) adaptation: to process different plastic, matching the nose, and adaptability of different products. But generally strong adaptability, often plasticizing efficiency is low.
(5) manufacturing difficulty: must be easy manufacturing, low cost
2) design screw should be considered
(1) the material characteristics and the status of the geometric shape, size, temperature when machining. Due to the different physical properties of material is different, so the processing performance is different, have different request for the screw structure and geometric parameters.
(2) the mouth of the geometric forms and the resistance to the nose. Screw shape to match with them.
The structure of cylinder cooling and heating conditions. As in the feeding section of cylinder wall machining taper and longitudinal grooves and cooling, is improve the efficiency of solid conveying, screw should be considered in the design of improve the ability of melting rate, homogenization, make it match the charging period of delivery.
(3) the screw rotation speed
(4) extruder USES: do effects such as mixing, granulation and feeding, screw structure is different
2, regular full thread three screw design
Refers to the screw by charging period, compression, homogenization of thread three paragraphs, the extrusion process depend entirely on the thread to finish, in the form of a screw.
1) determine the screw type
According to the spiral groove depth from the charging period of deep section homogenization of shallow transition points:
(1) the gradient type: screw groove depth changes in the distance gradually becomes shallow. For the amorphous, heat-sensitive plastic processing, also can use crystal type.
(2) the mutation type: used for melting point mutation, low viscosity of plastic. Is not suitable for such as PA, PE, PP, PVC and other heat-sensitive plastic
2) screw diameter
Has been standardized, its size according to the general kind of section size, processing plastic products processing, the extrusion amount needed for sure
3) the screw length to diameter ratio L/Db
The length to diameter ratio, the greater the plastic in the longer you stay in the cylinder, plasticizing, even more fully, to ensure the quality
Single screw extrusion machine technical parameters and models
1, single screw extruder technology parameters
Db: screw diameter refers to the large diameter, series standard 20, 30, 45, 65, 90, 120, 90, 165, 200, 250, 200
Screw length to diameter ratio L/Db: working parts of screw length and the screw diameter ratio
The screw rotation speed range: nmin - nmax r/min
Drive screw motor power P: KW
Extruder production capacity Q: the amount of plastic extrusion per hour
Than the flow per hour per week extruder production capacity
Nominal rating Processing kg plastic motor power needed for an hour
2, model
SL - 150 indicates the screw diameter of 150 mm, length to diameter ratio systematically plastic extruding
Extrusion process parameters
1, the temperature
Extrusion temperature has a nitrogen-treated barrel temperature and plastic temperature, the temperature of screw, usually we measure cylinder temperature. Temperature controlled by heating cooling systems, due to the screw structure, heating and cooling system is not stable, the screw rotation speed change makes extrusion materials such as fluctuations in radial and axial temperature, which affect products quality, the products is not the same as the intensity of each point, residual stress, surface gray matte. In order to guarantee the product quality, temperature should be stable.
2, pressure
Due to the screw and cylinder structure, the nose, the resistance of the filter, filter plate, make plastic internal pressure exists. Pressure changes as shown in figure, there is also volatile.
3, extrusion rate,
Per unit time by the extruder die extrusion plastic quality or length. Factors influencing the extrusion rate: the nose resistance, the structure of the screw with a nitrogen-treated barrel, screw speed, heating, cooling system, plastic properties. But when the product is set, the extrusion rate is only related to the screw rotation speed. Extrusion rate fluctuations, also affect products geometric shapes and sizes.
Temperature, pressure, extrusion rate, there is a wave phenomenon, in order to ensure the quality of products, should be properly designed screw and screw speed, good control of heating cooling system stability, in order to reduce parameter fluctuations.
Extrusion molding process
General according to the type of polymer and the shape of the products or semi-finished products, selected extruder, the nose and mouth mold, and finalize the design and drawing the corresponding auxiliary device, and then determine the extrusion processing conditions such as screw speed, head pressure, material temperature, and finalize the design temperature, pulling speed, etc. In extrusion process, the material is typically through plasticate, but to finalize the design method is different. Plastic extrusion, for example, often need cooling finalize the design, make its curing, and extruding rubber semi-finished products, it still needs further sulfide. Adopt different extrusion equipment and process, can get different products.
aggregate
After polymer mixed with various additives, to melt in the extrusion machine, and further mixing. Through the mode, the orifice form root stock, then cut into aggregate. And cold cut cut have eagerly grain. The former stock from the mouth after the mould, with air or water cooling, side immediately with rotating knife cut off. The latter is to strip all after cooling, and then into the dicing machine cut grain.
Sheet and film
Every thickness above 0.25 mm, length is much greater than the width of the flat sheet products said; According to thin film thickness is less than 0.25 mm. Such as the flat die out membrane, through a very bright and clean the surface of the cooling drum after heating, flat membrane can be obtained, this method is also called LiuYanFa came out. This is a manufacturing polypropylene film commonly used method. If the income into the stenter flat membrane, at the same time in the longitudinal and transverse tensile 4 ~ 10 times (also can be longitudinal tensile first, again transverse tensile), the biaxial oriented film can be obtained from. Due to stretching, the macromolecular orientation, so the film strength is high, but the floods, permeability is reduced. Often used in the manufacture of polypropylene and polyester film. Such as materials and foaming agent, and the use of special screw and die, also can be obtained low foam plank.
Coating line
When the metal bare wire through a tee mold, molten plastic is around bare wire to form a cladding layer (figure 3 [coated wire with the nose]), the coating line is cooled after winding, a quick all kinds of wire and cable products.
Pipe extrusion process
Equipment: extruder, head, finalize the design equipment, cooling tank, traction device and cutting device
1, molding
By the extrusion die. Melt through the filter and filter plate, diversion area, compression area, become tube forming zone.
2, finalize the design
Methods: bore diameter and outer diameter sizing method (internal pressure and vacuum)
3, pipe extrusion process condition control
Temperature: cylinder, the nose and mouth, mold temperature is the main factor affecting the quality of plasticizing and products. Extrusion pipe generally low temperature, high viscosity, is helpful to finalize the design.
Extrusion rate, affect the yield and quality, its value is determined by the screw rotational speed
Traction speed: influence the accuracy of the wall thickness and diameter of tube, should be compatible with the extrusion speed.
The compressed air pressure: the pressure stress within 0.02 ~ 0.05 MPa
Blown film method of molding process
1, extrusion and blowing
Equipment: extruder, head, cooling device, splint, traction roller, guide roller, winding device.
2, blown film extrusion process conditions
Temperature: cylinder temperature, head and neck. Temperature is too high, thin film brittle, tensile strength decreased; Too high and low tensile strength, surface gloss and transparency decline, a weld marks.
Blowing ratio and draw ratio: blowing ratio - the ratio of diameter to mouth mould tube membrane (2-3); Draft ratio - membrane elongation ratio (4-6).
Cooling rate: the cooling device regulation. Frozen line - blowing tube membrane has been cooling line shape; The farther the frozen line, the slower cooling rate, lateral film easy to tear.
Extrusion molding process applications
Use a few extrusion machine, at the same time supply several kinds of plastic, then by sharing out the nose, form an integral part of the composite products. For example with A, B, C three kinds of plastic extrusion, can produce all kinds of composite film, composite sheet, plate, profiles and pipes.
Rubber filter
In manufacturing thin-wall rubber products, in order to prevent gas leakage, leakage in products, rubber not contain impurities, general before joining vulcanizing agent filtering rubber extruder, put a layer or multi-layer mesh in the nose, to filter the impurities in the plasticizing material.
Tire tread and inner tube manufacturing tread points overall extrusion and layered extrusion. Overall will make available a extruder a rubber by flat die extrusion; Also can use two kinds of rubber, tire crown and sidewall material) two extrusion machine, extrusion, within the total of the extrusion combined into a whole tread. Layered extrusion with two sets of two kinds of rubber extruder respectively to squeeze into the tire crown and sidewall, hot laminating in conveyor belt, and the more disk adjustable roller as whole. Tube extrusion and pipe extrusion, tire tube squeeze into, after the cut, the joint forming again.
Melt spinning
Some in melt spinning, the viscosity of resin commonly used extruder to molten material. The molten material directly through the filter into the spinneret, or use the jet pump into the spinneret
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