橡膠片材擠出機

橡膠片材擠出機  橡膠片材機

橡膠片材擠出成型定義
  在纖維化學工業中也有用擠出機向噴絲頭供料，以進行熔體紡絲。擠出應用于熱塑性塑料和橡膠的加工，可進行配料、造粒、膠料過濾等，可連續化生產，制造各種連續制品如板材(或片材)、薄膜、電線電纜包覆、橡膠輪胎胎面條、內胎胎筒、密封條等，其生產效率高。在合成樹脂生產中，擠出機可作為反應器，連續完成聚合和成型加工,在橡膠工業中壓縮比不同的擠出機可以用來塑煉天然膠.不同材料的擠出機器的壓縮比有些不同.
橡膠片材擠出成型原理
  料自料斗進入料筒，在螺桿旋轉作用下，通過料筒內壁和螺桿表面摩擦剪切作用向前輸送到加料段，在此松散固體向前輸送同時被壓實；在壓縮段，螺槽深度變淺，進一步壓實，同時在料筒外加熱和螺桿與料筒內壁摩擦剪切作用，料溫升高開始熔融，壓縮段結束；均化段使物料均勻，定溫、定量、定壓擠出熔體，到機頭后成型，經定型得到制品。
  １、擠出方法
  按塑化方式：干法擠出與濕法擠出
  按加壓方式：連續擠出與間歇擠出
  2、特點
  生產連續、效率高、操作簡單、應用范圍廣
擠出成型設備
  1、主機
  擠出系統：由螺桿與料筒組成，是擠出機關鍵部分。其作用是塑化物料，定量、定壓、定溫擠出熔體
  傳動系統：驅動螺桿，提高所需的紐矩和轉矩
  加熱和冷卻系統：保證塑料和擠出系統在成型過程中溫度達工藝要求
  2、輔機
  由機頭、定型裝置、冷卻裝置、牽引裝置、卷取裝置、切割組成
  3、控制系統
  由電器、儀表和執行機構組成
  作用：控制主、輔機電動機、以滿足所需轉速和功率；控制主輔機溫度、壓力、流量，保證制品質量；實現擠出機組的自動控制，保證主、輔機協調運行。
橡膠片材擠出機的概述
  橡膠片材擠出機的主機是橡膠片材機，它由擠壓系統、傳動系統和加熱冷卻系統組成。
  1.擠壓系統 擠壓系統包括螺桿、機筒、料斗、機頭、和模具，塑料通過擠壓系統而塑化成均勻的熔體，并在這一過程中所建立壓力下，被螺桿連續的擠出機頭。
  （1） 螺桿：是橡膠片材機的最主要部件，它直接關系到橡膠片材機的應用范圍和生產率，由高強度耐腐蝕的合金鋼制成。
  （2）機筒：是一金屬圓筒，一般用耐熱、耐壓強度較高、堅固耐磨、耐腐蝕的合金鋼或內襯合金鋼的復合鋼管制成。機筒與螺桿配合，實現對塑料的粉碎、軟化、熔融、塑化、排氣和壓實，并向成型系統連續均勻輸送膠料。一般機筒的長度為其直徑的15～30 倍，以使塑料得到充分加熱和充分塑化為原則。
  （3） 料斗：料斗底部裝有截斷裝置，以便調整和切斷料流，料斗的側面裝有視孔和標定計量裝置。
  （4）機頭和模具：機頭由合金鋼內套和碳素鋼外套構成，機頭內裝有成型模具。機頭的作用是將旋轉運動的塑料熔體轉變為平行直線運動，均勻平穩的導入模套中，并賦予塑料以必要的成型壓力。塑料在機筒內塑化壓實，經多孔濾板沿一定的流道通過機頭脖頸流入機頭成型模具，模芯模套適當配合，形成截面不斷減小的環形空隙，使塑料熔體在芯線的周圍形成連續密實的管狀包覆層。為保證機頭內塑料流道合理，消除積存塑料的死角，往往安置有分流套筒，為消除塑料擠出時壓力波動，也有設置均壓環的。機頭上還裝有模具校正和調整的裝置，便于調整和校正模芯和模套的同心度。
  橡膠片材機按照機頭料流方向和螺桿中心線的夾角，將機頭分成斜角機頭（夾角120o）和直角機頭。機頭的外殼是用螺栓固定在機身上，機頭內的模具有模芯坐，并用螺帽固定在機頭進線端口，模芯座的前面裝有模芯，模芯及模芯座的中心有孔，用于通過芯線；在機頭前部裝有均壓環，用于均衡壓力；擠包成型部分由模套座和模套組成，模套的位置可由螺栓通過支撐來調節，以調整模套對模芯的相對位置，便于調節擠包層厚度的均勻性。機頭外部裝有加熱裝置和測溫裝置。
  2.傳動系統 傳動系統的作用是驅動螺桿，供給螺桿在擠出過程中所需要的力矩和轉速，通常由電動機、減速器和軸承等組成。
  3.加熱冷卻裝置 加熱與冷卻是塑料擠出過程能夠進行的必要條件。
  （1） 現在橡膠片材機通常用的是電加熱，分為電阻加熱和感應加熱，加熱片裝于機身、機脖、機頭各部分。加熱裝置由外部加熱筒內的塑料，使之升溫，以達到工藝操作所需要的溫度。
  （2）冷卻裝置是為了保證塑料處于工藝要求的溫度范圍而設置的。具體說是為了排除螺桿旋轉的剪切摩擦產生的多余熱量，以避免溫度過高使塑料分解、焦燒或定型困難。機筒冷卻分為水冷與風冷兩種，一般中小型橡膠片材機采用風冷比較合適，大型則多采用水冷或兩種形式結合冷卻；螺桿冷卻主要采用中心水冷，目的是增加物料固體輸送率，穩定出膠量，同時提高產品質量；但在料斗處的冷卻，一是為了加強對固體物料的輸送作用，防止因升溫使塑料粒發粘堵塞料口，二是保證傳動部分正常工作。
  二、 輔助設備
  橡膠片材擠出機組的輔機主要包括放線裝置、校直裝置、預熱裝置、冷卻裝置、牽引裝置、計米器、火花試驗機、收線裝置。擠出機組的用途不同其選配用的輔助設備也不盡相同。如還有切斷器、吹干器、印字裝置等。
  校直裝置：塑料擠出廢品類型中最常見的一種是偏心，而線芯各種型式的彎曲則是產生絕緣偏心的重要原因之一。在護套擠出中，護套表面的刮傷也往往是由纜芯的彎曲造成的。因此，各種橡膠片材機組中的校直裝置是必不可少。校直裝置的主要型式有：滾筒式（分為水平式和垂直式）；滑輪式（分為單滑輪和滑輪組）；絞輪式，兼起拖動、校直、穩定張力等多種作用；壓輪式（分為水平式和垂直式）等。
  預熱裝置：纜芯預熱對于絕緣擠出和護套擠出都是必要的。對于絕緣層，尤其是薄層絕緣，不能允許氣孔的存在，線芯在擠包前通過高溫預熱可以徹底清除表面的水份、油污。對于護套擠出來講，其主要作用在于烘干纜芯，防止由于潮氣（或繞包墊層的濕氣）的作用使護套中出現氣孔的可能。預熱還可防止擠出中塑料因驟冷而殘留內壓力的作用。在擠塑料過程中，預熱可消除冷線進入高溫機頭，在模口處與塑膠接觸時形成的懸殊溫差，避免塑膠溫度的波動而導致擠出壓力的波動，從而穩定擠出量，保證擠出質量。橡膠片材機組中均采用電加熱線芯預熱裝置，要求有足夠的容量并保證升溫迅速，使線芯預熱和纜芯烘干效率高。預熱溫度受放線速度的制約，一般與機頭溫度相仿即可。
  冷卻裝置：成型的塑料擠包層在離開機頭后，應立即進行冷卻定型，否則會在重力的作用下發生變形。冷卻的方式通常采用水冷卻，并根據水溫不同，分為急冷和緩冷。急冷就是冷水直接冷卻，急冷對塑料擠包層定型有利，但對結晶高聚物而言，因驟熱冷卻，易在擠包層組織內部殘留內應力，導致使用過程中產生龜裂，一般 PVC塑膠層采用急冷。緩冷則是為了減少制品的內應力，在冷卻水槽中分段放置不同溫度的水，使制品逐漸降溫定型，對PE、PP的擠出就采用緩冷進行，即經過熱水、溫水、冷水三段冷卻。
  三、 控制系統
  橡膠片材擠出機的控制系統包括加熱系統、冷卻系統及工藝參數測量系統，主要由電器、儀表和執行機構（即控制屏和操作臺）組成。其主要作用是：控制和調節主輔機的拖動電機，輸出符合工藝要求的轉速和功率，并能使主輔機協調工作；檢測和調節橡膠片材機中塑料的溫度、壓力、流量；實現對整個機組的控制或自動控制。
  擠出機組的電氣控制大致分為傳動控制和溫度控制兩大部分，實現對擠塑工藝包括溫度、壓力、螺桿轉數、螺桿冷卻、機筒冷卻、制品冷卻和外徑的控制，以及牽引速度、整齊排線和保證收線盤上從空盤到滿盤的恒張力收線控制。
  1. 橡膠片材機主機的溫度控制
  電線電纜絕緣和護套的塑料擠出是根據熱塑性塑料變形特性，使之處于粘流態進行的。除了要求螺桿和機筒外部加熱，傳到塑料使之融化擠出，還要考慮螺桿擠出塑料時其本身的發熱，因此要求主機的溫度應從整體來考慮，既要考慮加熱器加熱的開與關，又要考慮螺桿的擠出熱量外溢的因素予以冷卻，要有有效的冷卻設施。并要求正確合理的確定測量元件熱電偶的位置和安裝方法，能從控溫儀表讀數準確反映主機各段的實際溫度。以及要求溫控儀表的精度與系統配合好，使整個主機溫度控制系統的波動穩定度達到各種塑料的擠出溫度的要求。
  2. 橡膠片材機的壓力控制
  為了反映機頭的擠出情況，需要檢測擠出時的機頭壓力，由于國產橡膠片材機沒有機頭壓力傳感器，一般是對螺桿擠出后推力的測量替代機頭壓力的測量，螺桿負荷表（電流表或電壓表）能正確反映擠出壓力的大小。擠出壓力的波動，也是引起擠出質量不穩的重要因素之一，擠出壓力的波動與擠出溫度、冷卻裝置的使用，連續運轉時間的長短等因素密切相關。當發生異常現象時，能排除的迅速排除，必須重新組織生產的則應果斷停機，不但可以避免廢品的增多，更能預防事故的發生。通過檢測的壓力表讀數，就可以知道塑料在擠出時的壓力狀態，一般取后推力極限值報警控制。
  3. 螺桿轉速的控制
  螺桿轉速的調節與穩定是主機傳動的重要工藝要求之一。螺桿轉速直接決定出膠量和擠出速度，正常生產總希望盡可能實現最高轉速及實現高產，對橡膠片材機要求螺桿轉速從起動到所需工作轉速時，可供使用的調速范圍要大。而且對轉速的穩定性要求高，因為轉速的波動將導致擠出量的波動，影響擠出質量，所以在牽引線速度沒有變化情況下，就會造成線纜外徑的變化。同理如牽引裝置線速波動大也會造成線纜外徑的變化，螺桿和牽引線速度可通過操作臺上相應儀表反映出來，擠出時應密切觀察，確保優質高產。
  4. 外徑的控制
  如上所述為了保證制品線纜外徑的尺寸，除要求控制線芯（纜芯）的尺寸公差外，在擠出溫度、螺桿轉速、牽引裝置線速度等方面應有所控制保證，而外徑的測量控制則綜合反映上述控制的精度和水平。在橡膠片材機組設備中，特別是高速擠塑生產線上，應配用在線外徑檢測儀，隨時對線纜外徑進行檢測，并且將超差信號反饋以調整牽引或螺桿的轉速，糾正外徑超差。
  5. 收卷要求的張力控制
  為了保證不同線速下的收線，從空盤到滿盤工作的恒張力要求，希望收排線裝置有貯線張力調整機構，或在電氣上考慮恒線速度系統和恒張力系統的收卷等等。
  6. 整機的電氣自動化控制
  這是實現高速擠出生產線應具備的工藝控制要求，主要是：開機溫度聯鎖；工作壓力保護與聯鎖；擠出、牽引兩大部件傳動的比例同步控制；收線與牽引的同步控制；外徑在線檢測與反饋控制；根據各種不同需要組成部件的單機與整機跟蹤的控制。
擠出機分類
  按數量分：無螺桿、單螺桿、雙螺桿
  按空間位置：臥式和立式
  按螺桿轉速：普通、高速和超高速
  可否排氣：排氣式和非排氣式
  按裝配結構：整體式和分開式
  最常用臥式單螺桿非排氣式整體式擠出機
擠出機的主要零部件
  一、螺桿
  1、評價螺桿性能的標準和設計螺桿應考慮的因素
  1）評價螺桿性能標準
  ①塑化質量：必須滿足質量要求。制品質量與機頭、輔機有關，但與螺桿的塑化質量關系更大，如溫度不均、軸向壓力波動、徑向溫度大、染色等分散不均勻，這都直接影響制品質量。
  ②產量：在保證質量前提下，通過機頭擠出量。好的螺桿，應具有高的塑化能力
  ③名義比功率單耗：每擠1Kg塑料消耗的產量即P/Q（功率/產量），保證質量下，單耗越少越好。
  ④適應性：對加工不同塑料、匹配不同機頭和不同制品的適應能力。但一般適應性強，往往塑化效率低。
  ⑤制造難易：必須易制造、成本低
  2）設計螺桿應考慮
  ①物料特性及加工時的幾何形狀、尺寸、溫度狀況。由于不同物料物理特性不同，因此加工性能不同，對螺桿結構和幾何參數有不同要求。
  ②口模的幾何形式和機頭阻力特性。螺桿形狀要與他們相匹配。
  料筒的結構形式和加熱冷卻情況。如在加料段料筒內壁加工出錐度和縱向溝槽并冷卻，則提高固體輸送效率，螺桿在設計時應考慮提高熔融速率、均化能力，使之與加料段輸送相匹配。
  ③螺桿轉速
  ④擠出機用途：作混煉、造粒和喂料等作用，螺桿結構有所不同
  2、常規全螺紋三段螺桿設計
  指螺桿由加料段、壓縮段、均化段三段螺紋組成，其擠出過程完全依靠螺紋的形式來完成的一種螺桿。
  1）螺桿類型確定
  按螺槽深度從加料段較深向均化段較淺的過渡情況分：
  ①漸變型：螺槽深度變化在較長距離逐漸變淺。用于無定型、熱敏性塑料加工、也可用結晶型。
  ②突變型：用于熔點突變、粘度低的塑料。如PA、PE、PP，不適于PVC等熱敏性塑料
  2）螺桿直徑
  已經標準化，其大小一般根據所加工制品的斷面尺寸、加工塑料種類、所需擠出量確定
  3）螺桿長徑比L/Db
  長徑比越大，則塑料在料筒中停留時間越長，塑化更充分、均勻，以保證制品質
單螺桿擠出機技術參數和型號
  1、單螺桿擠出機技術參數
  螺桿直徑Db：指大徑，系列標準20、30、45、65、90、120、150、165、200、250、300
  螺桿長徑比L/Db：螺桿工作部分長度與螺桿直徑比值
  螺桿轉速范圍：nmin-nmax r/min
  驅動螺桿電機功率P：KW
  擠出機生產能力Q：每小時擠出的塑料量
  比流量每小時每轉一周擠出機生產能力
  名義比功率 每小時加工kg塑料所需電機功率
  2、型號
  SL-150表示螺桿直徑為150mm，長徑比為20：1塑料擠出
擠出工藝參數
  1、溫度
  擠出成型溫度有料筒溫度、塑料溫度、螺桿溫度，一般我們測料筒溫度。溫度由加熱冷卻系統控制，由于螺桿結構、加熱冷卻系統不穩定、螺桿轉速變化等原因使擠出物料溫度在徑向和軸向都存在波動，從而影響制品質量，制品各點強度不一樣，產生殘余應力，表面灰暗無光澤。為保證制品質量，溫度應穩定。
  2、壓力
  由于螺桿和料筒結構，機頭、過濾網、過濾板的阻力，使塑料內部存在壓力。壓力變化如圖，壓力同樣存在波動。
  3、擠出速率
  單位時間內由擠出機口模擠出的塑料質量或長度。影響擠出速率因素：機頭阻力、螺桿與料筒結構、螺桿轉速、加熱、冷卻系統、塑料特性。但當產品已定，擠出速率僅與螺桿轉速有關。擠出速率也存在波動，影響制品幾何形狀和尺寸。
  溫度、壓力、擠出速率都存在波動現象，為了保證制品質量，應正確設計螺桿、控制好加熱冷卻系統和螺桿轉速穩定性，以減少參數波動。
擠出成型工藝
  一般根據所加工聚合物的類型和制品或半成品的形狀，選定擠出機、機頭和口模，以及定型和牽引等相應的輔助裝置，然后確定擠出工藝條件如螺桿轉速、機頭壓力、物料溫度，以及定型溫度、牽引速度等。在擠出過程中，物料一般都要經過塑煉，但定型方法則有所不同。例如，擠出的塑料常需冷卻定型，使其固化，而擠出橡膠的半成品，則尚需進一步硫化。采用不同的擠出設備和工藝，可得到不同的制品。
  粒料
  聚合物與各種添加劑混合后，送入擠出機中熔化，并進一步混合均勻。通過多孔口模，形成多根條料，再切斷成粒料。切斷有熱切粒和冷切粒之分。前者條料離口模后，一邊用空氣或水冷卻，一邊立即用旋轉刀切斷。后者是將條料全部冷卻后，再送入切粒機切粒。
  片材和薄膜
  凡厚度在0.25mm以上，長度比寬度大很多的扁平制品稱片材；厚度小于0.25mm者稱薄膜。如將扁平口模出來的膜狀物，通過一表面十分光潔的冷卻轉鼓冷卻定型,即可制得平膜,此法也稱擠出流延法。這是制造聚丙烯薄膜常用方法。如果將所得平膜送入拉幅機，在縱向及橫向同時拉伸 4～10倍（也可先縱向拉伸，再橫向拉伸）,則可制得雙軸定向薄膜。由于拉伸時,大分子取向，因此薄膜強度很高，但透水、透氣性有所降低。常用于制造聚丙烯和聚酯薄膜。如物料內加發泡劑，并采用特殊螺桿和口模，也可制得低發泡沫塑料板材。
  包覆線
  當金屬裸線通過一個 T形口模時，熔融塑料即圍繞裸線而形成包覆層（圖3[包覆線用機頭]）,包覆線被冷卻卷繞后，即得各種電線電纜制品。
管材擠出工藝
  設備：擠出機、機頭、定型裝置、冷卻槽、牽引設備和切割設備
  1、成型
  由擠出模具實現。熔體經過濾網和過濾板，分流區、壓縮區、成型區而成為管狀物。
  2、定型
  方法：內徑定徑與外徑定徑（內壓法與真空法）
  3、管材擠出工藝條件控制
  溫度：料筒、機頭和口模溫度，是影響塑化和制品質量的主要因素。擠出管材溫度一般較低，粘度高，有利于定型。
  擠出速率：影響產量和質量，其值決定于螺桿轉速
  牽引速度：影響管材壁厚和直徑的的精確性，要與擠出速度相適應。
  壓縮空氣壓力：內壓法壓力0.02~0.05MPa
吹塑薄膜法成型工藝
  1、擠出與吹脹
  設備：擠出機及機頭、冷卻裝置、夾板、牽引輥、導向輥、卷取裝置。
  2、吹塑薄膜擠出工藝條件
  溫度：料筒、機頭和機頸溫度。溫度過高，薄膜發脆，抗拉強度下降；過高，抗拉強度低、表面光澤差、透明度下降、有熔接痕。
  吹脹比與牽伸比：吹脹比—管膜直徑與口模之比（2-3）；牽伸比—薄膜伸長倍數（4-6）。
  冷卻速度：由冷卻裝置調節。冷凍線—吹脹管膜上已冷卻定型的線；冷凍線越遠，冷卻速度越慢，薄膜橫向易撕裂。
擠出成型工藝應用
  采用幾臺擠出機,同時供應幾種塑料,再通過共用機頭擠出，形成一個整體的復合制品。例如用A、B、C三種塑料共擠出，可生產各種復合薄膜、復合片材、板材、型材和管材。
  膠料過濾
  在制造薄壁橡膠制品時，為了防止制品發生漏氣、漏水，膠料不能含有雜質，一般在加入硫化劑前用擠出機過濾膠料，即在機頭處放置一層或多層濾網，以濾去塑化物料中雜質。
  輪胎胎面和內胎制造 胎面分整體擠出和分層擠出。整體擠出可用一臺擠出機將一種膠料經扁平口模擠出；也可用兩種膠料（胎冠料和胎側料）兩臺擠出機共擠出，在共擠出機頭內結合成一個整體胎面。分層擠出則用兩臺擠出機分別將兩種膠料擠成胎冠和胎側，再在運輸帶上進行熱貼合，并經多圓盤活絡輥壓為整體。內胎擠出和管子擠出相似，胎筒擠成后，經切斷，再接頭成型。
  熔體紡絲
  一些粘度大的樹脂在熔體紡絲時，常用擠出機來熔融物料。熔好的物料直接經過過濾器進入噴絲頭，或用噴絲泵打入噴絲頭

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