1.異型口模

口(kou)(kou)(kou)模(mo)異型(xing)(xing)(xing)化是指擠出機頭的口(kou)(kou)(kou)模(mo)或芯棒局部位置(zhi)開設凹槽，增大(da)對應(ying)制(zhi)(zhi)件拐角處的口(kou)(kou)(kou)模(mo)間隙，以(yi)增加(jia)型(xing)(xing)(xing)坯(pi)局部位置(zhi)的壁(bi)(bi)厚，得到異型(xing)(xing)(xing)化的型(xing)(xing)(xing)坯(pi)，彌補吹脹(zhang)比不一致造成的徑向壁(bi)(bi)厚不均(jun)，從(cong)而得到壁(bi)(bi)厚較為均(jun)勻的制(zhi)(zhi)件。針對性地采(cai)用異型(xing)(xing)(xing)口(kou)(kou)(kou)模(mo)，并通過多次試(shi)模(mo)、優化、設計加(jia)工出合理的異型(xing)(xing)(xing)口(kou)(kou)(kou)模(mo)，可以(yi)極大(da)提高制(zhi)(zhi)件壁(bi)(bi)厚分布的均(jun)勻性。

2.軸(zhou)向壁厚控(kong)制(zhi)技(ji)術

軸向壁厚(hou)(hou)(hou)控制(zhi)技術(shu)的(de)(de)(de)作用是使得擠出的(de)(de)(de)塑料(liao)型(xing)坯，根據(ju)制(zhi)品(pin)不(bu)同的(de)(de)(de)吹脹比(bi)(bi)沿軸向獲得不(bu)同的(de)(de)(de)厚(hou)(hou)(hou)度，從而保證(zheng)最終制(zhi)品(pin)有比(bi)(bi)較均勻的(de)(de)(de)壁厚(hou)(hou)(hou)。它是通過使芯棒或(huo)口模根據(ju)預設位置作軸向運動而改(gai)變(bian)機(ji)頭的(de)(de)(de)開口量，達到改(gai)變(bian)塑料(liao)型(xing)坯壁厚(hou)(hou)(hou)的(de)(de)(de)目的(de)(de)(de)。目前(qian)中空成(cheng)形機(ji)的(de)(de)(de)儲料(liao)機(ji)頭一般都具有軸向型(xing)坯控制(zhi)功能(neng)，其控制(zhi)點(dian)從30點(dian)到256點(dian)不(bu)等。

3.徑向壁(bi)厚控制技(ji)術

采用軸向(xiang)壁(bi)厚(hou)(hou)控制技術(shu)雖然能改(gai)善吹塑制品高度方向(xiang)上的壁(bi)厚(hou)(hou)分布(bu)，但(dan)由于其擠(ji)出(chu)塑料型(xing)坯的水平(ping)截面仍呈等厚(hou)(hou)圓(yuan)形，對部(bu)分在徑向(xiang)某(mou)一部(bu)位有較大吹脹比要求的制品顯得仍不是最(zui)佳(jia)，因此(ci)便產生了(le)徑向(xiang)壁(bi)厚(hou)(hou)控制技術(shu)。徑向(xiang)壁(bi)厚(hou)(hou)控制技術(shu)可以使(shi)擠(ji)出(chu)的型(xing)坯在所要求的區段內(nei)呈非圓(yuan)截面的變化。徑向(xiang)壁(bi)厚(hou)(hou)程序(xu)控制技術(shu)發展至今，大致形成了(le)2種典(dian)型(xing)的設(she)計，一種稱(cheng)為柔性環式，另(ling)一種稱(cheng)為口緣修形式。

(1)柔性環技術

柔性(xing)環式是通(tong)過電液伺(si)服控(kong)(kong)制(zhi)薄壁撓性(xing)環在1個(ge)方向(xiang)或2個(ge)對稱方向(xiang)上的變(bian)形(xing)(xing)來改(gai)變(bian)擠出型坯(pi)的厚(hou)度(du)。它(ta)的特點(dian)(dian)(dian)是無論吹(chui)制(zhi)什么形(xing)(xing)狀的制(zhi)品，只要口模直徑(jing)不變(bian)，徑(jing)向(xiang)控(kong)(kong)制(zhi)都(dou)能(neng)發揮作用。對中空成形(xing)(xing)塑料(liao)型坯(pi)徑(jing)向(xiang)壁厚(hou)控(kong)(kong)制(zhi)系統(tong)的研制(zhi)工作，最近在江蘇獲得了關鍵性(xing)的技術(shu)突破。這項控(kong)(kong)制(zhi)技術(shu)可(ke)以實現(xian)塑料(liao)型坯(pi)徑(jing)向(xiang)壁厚(hou)的多(duo)點(dian)(dian)(dian)準確控(kong)(kong)制(zhi)，控(kong)(kong)制(zhi)點(dian)(dian)(dian)可(ke)以方便地實現(xian)2～16點(dian)(dian)(dian)控(kong)(kong)制(zhi)甚至更多(duo)點(dian)(dian)(dian)控(kong)(kong)制(zhi)，目前(qian)正在產(chan)業(ye)化(hua)中。

(2)口緣修形技術

口緣修形(xing)是靠修形(xing)口模環(huan)的(de)(de)(de)上下(xia)移動(dong)來實(shi)現型坯壁厚改變的(de)(de)(de)。與撓(nao)性環(huan)結構(gou)相(xiang)比，其最(zui)大(da)的(de)(de)(de)優點是使用壽命(ming)長，加工技術難度低(di)。在(zai)某(mou)些設計中(zhong)，口模環(huan)的(de)(de)(de)修緣部分做成活動(dong)塊(kuai)嵌入式(shi)，方便更(geng)換(huan)(huan)，減(jian)少更(geng)換(huan)(huan)時的(de)(de)(de)成本。這種(zhong)形(xing)式(shi)的(de)(de)(de)設計，還需要進行(xing)深入研究，降低(di)成本，加快推廣步伐。

徑向壁(bi)(bi)厚控(kong)制(zhi)(zhi)技(ji)術對于提(ti)高大(da)(da)型(xing)(xing)中(zhong)空(kong)制(zhi)(zhi)品的(de)(de)(de)品質是一(yi)個(ge)有效的(de)(de)(de)方法，還能(neng)減輕制(zhi)(zhi)品的(de)(de)(de)質量。以200L塑料(liao)(liao)桶(tong)容器為例，至少可節(jie)省5%～10%的(de)(de)(de)原料(liao)(liao)。目(mu)前加工一(yi)套(tao)大(da)(da)型(xing)(xing)徑向壁(bi)(bi)厚控(kong)制(zhi)(zhi)裝置的(de)(de)(de)附加費用較高，隨著徑向壁(bi)(bi)厚控(kong)制(zhi)(zhi)技(ji)術的(de)(de)(de)深(shen)入研究和發(fa)展，將在更多的(de)(de)(de)大(da)(da)中(zhong)型(xing)(xing)擠(ji)出吹塑中(zhong)空(kong)成(cheng)形機上應用。

軸向(xiang)壁(bi)(bi)(bi)厚控制(zhi)與(yu)徑向(xiang)壁(bi)(bi)(bi)厚控制(zhi)的聯合作用，可獲(huo)得最(zui)佳的塑料型坯，即可獲(huo)得更(geng)為理想的制(zhi)品壁(bi)(bi)(bi)厚分布。目(mu)前國內(nei)多(duo)家中(zhong)空成形機制(zhi)造廠家可在大型中(zhong)空成形機上選擇(ze)配套徑向(xiang)壁(bi)(bi)(bi)厚控制(zhi)系統(tong)。

(3)型坯溫差法

型(xing)坯的(de)變(bian)(bian)(bian)(bian)形(xing)(xing)抗(kang)力可(ke)用粘(zhan)度(du)(du)(du)來(lai)表示，粘(zhan)度(du)(du)(du)的(de)大(da)(da)(da)(da)(da)小(xiao)(xiao)(xiao)與其(qi)溫(wen)(wen)(wen)度(du)(du)(du)的(de)高低(di)有(you)關。型(xing)坯溫(wen)(wen)(wen)度(du)(du)(du)高，黏度(du)(du)(du)小(xiao)(xiao)(xiao)，變(bian)(bian)(bian)(bian)形(xing)(xing)抗(kang)力小(xiao)(xiao)(xiao)，吹(chui)塑過(guo)程中(zhong)容易(yi)變(bian)(bian)(bian)(bian)形(xing)(xing)，變(bian)(bian)(bian)(bian)形(xing)(xing)量(liang)(liang)(liang)(liang)較(jiao)(jiao)(jiao)(jiao)(jiao)(jiao)大(da)(da)(da)(da)(da);相反，型(xing)坯溫(wen)(wen)(wen)度(du)(du)(du)低(di)，黏度(du)(du)(du)大(da)(da)(da)(da)(da)，變(bian)(bian)(bian)(bian)形(xing)(xing)抗(kang)力大(da)(da)(da)(da)(da)，吹(chui)塑過(guo)程中(zhong)不容易(yi)變(bian)(bian)(bian)(bian)形(xing)(xing)，變(bian)(bian)(bian)(bian)形(xing)(xing)量(liang)(liang)(liang)(liang)較(jiao)(jiao)(jiao)(jiao)(jiao)(jiao)小(xiao)(xiao)(xiao)。在擠(ji)出過(guo)程中(zhong)，通過(guo)冷卻設備(bei)強制(zhi)冷卻型(xing)坯吹(chui)脹(zhang)(zhang)比(bi)(bi)較(jiao)(jiao)(jiao)(jiao)(jiao)(jiao)大(da)(da)(da)(da)(da)的(de)部(bu)位(wei)(wei)，使型(xing)坯具有(you)合(he)理的(de)溫(wen)(wen)(wen)度(du)(du)(du)梯度(du)(du)(du)。型(xing)坯吹(chui)脹(zhang)(zhang)比(bi)(bi)較(jiao)(jiao)(jiao)(jiao)(jiao)(jiao)大(da)(da)(da)(da)(da)的(de)部(bu)位(wei)(wei)溫(wen)(wen)(wen)度(du)(du)(du)低(di)，粘(zhan)度(du)(du)(du)增(zeng)大(da)(da)(da)(da)(da)，變(bian)(bian)(bian)(bian)形(xing)(xing)抗(kang)力增(zeng)大(da)(da)(da)(da)(da)。在自由(you)吹(chui)脹(zhang)(zhang)階(jie)段(duan)，吹(chui)脹(zhang)(zhang)比(bi)(bi)較(jiao)(jiao)(jiao)(jiao)(jiao)(jiao)大(da)(da)(da)(da)(da)的(de)部(bu)位(wei)(wei)難于變(bian)(bian)(bian)(bian)形(xing)(xing)，變(bian)(bian)(bian)(bian)形(xing)(xing)量(liang)(liang)(liang)(liang)減(jian)小(xiao)(xiao)(xiao)，而(er)吹(chui)脹(zhang)(zhang)比(bi)(bi)較(jiao)(jiao)(jiao)(jiao)(jiao)(jiao)小(xiao)(xiao)(xiao)的(de)部(bu)位(wei)(wei)變(bian)(bian)(bian)(bian)形(xing)(xing)量(liang)(liang)(liang)(liang)增(zeng)大(da)(da)(da)(da)(da)。當變(bian)(bian)(bian)(bian)形(xing)(xing)量(liang)(liang)(liang)(liang)較(jiao)(jiao)(jiao)(jiao)(jiao)(jiao)小(xiao)(xiao)(xiao)部(bu)位(wei)(wei)完成變(bian)(bian)(bian)(bian)形(xing)(xing)，進入(ru)約束吹(chui)脹(zhang)(zhang)階(jie)段(duan)，吹(chui)脹(zhang)(zhang)比(bi)(bi)較(jiao)(jiao)(jiao)(jiao)(jiao)(jiao)大(da)(da)(da)(da)(da)部(bu)位(wei)(wei)繼(ji)續變(bian)(bian)(bian)(bian)形(xing)(xing)，直至吹(chui)脹(zhang)(zhang)成形(xing)(xing)制(zhi)件(jian)，以此提(ti)高制(zhi)件(jian)壁厚分布的(de)均勻性。

(4)真空(kong)吸塑與擠(ji)出(chu)吹塑相結(jie)合(he)

型(xing)(xing)(xing)坯(pi)(pi)(pi)(pi)各部位吹(chui)(chui)脹(zhang)比不同(tong)導致(zhi)制(zhi)(zhi)(zhi)(zhi)品壁厚(hou)(hou)不均勻。制(zhi)(zhi)(zhi)(zhi)品的(de)(de)吹(chui)(chui)脹(zhang)過程可分(fen)為(wei)(wei)(wei)自(zi)由吹(chui)(chui)脹(zhang)和約(yue)束(shu)吹(chui)(chui)脹(zhang)2個(ge)階(jie)段。從(cong)壓(ya)縮空氣進入型(xing)(xing)(xing)坯(pi)(pi)(pi)(pi)到型(xing)(xing)(xing)坯(pi)(pi)(pi)(pi)與(yu)模(mo)具內(nei)壁開始接(jie)觸(chu)(chu)為(wei)(wei)(wei)止稱為(wei)(wei)(wei)自(zi)由吹(chui)(chui)脹(zhang)階(jie)段。在(zai)(zai)這(zhe)一階(jie)段，型(xing)(xing)(xing)坯(pi)(pi)(pi)(pi)具有相(xiang)同(tong)的(de)(de)吹(chui)(chui)脹(zhang)比，在(zai)(zai)各個(ge)方(fang)向的(de)(de)變(bian)(bian)(bian)形(xing)(xing)都不受(shou)約(yue)束(shu)，可在(zai)(zai)任意(yi)方(fang)向膨脹(zhang)變(bian)(bian)(bian)形(xing)(xing)，且較均勻。從(cong)型(xing)(xing)(xing)坯(pi)(pi)(pi)(pi)與(yu)模(mo)具型(xing)(xing)(xing)腔開始接(jie)觸(chu)(chu)到型(xing)(xing)(xing)坯(pi)(pi)(pi)(pi)完全與(yu)模(mo)具內(nei)壁貼(tie)合(he)為(wei)(wei)(wei)止稱之為(wei)(wei)(wei)約(yue)束(shu)吹(chui)(chui)脹(zhang)階(jie)段。在(zai)(zai)這(zhe)一階(jie)段，型(xing)(xing)(xing)坯(pi)(pi)(pi)(pi)外表面(mian)受(shou)模(mo)具冷卻作(zuo)用，溫(wen)度下降，粘度增大，變(bian)(bian)(bian)形(xing)(xing)較為(wei)(wei)(wei)困難，甚至不再變(bian)(bian)(bian)形(xing)(xing)，導致(zhi)制(zhi)(zhi)(zhi)(zhi)品壁厚(hou)(hou)較大;沒有接(jie)觸(chu)(chu)模(mo)具型(xing)(xing)(xing)腔的(de)(de)坯(pi)(pi)(pi)(pi)料，溫(wen)度相(xiang)對(dui)較高，粘度較小，變(bian)(bian)(bian)形(xing)(xing)較為(wei)(wei)(wei)容易，迅速變(bian)(bian)(bian)薄，緊貼(tie)模(mo)具內(nei)表面(mian)，導致(zhi)制(zhi)(zhi)(zhi)(zhi)品壁厚(hou)(hou)較小，最終使整個(ge)制(zhi)(zhi)(zhi)(zhi)件(jian)壁厚(hou)(hou)不均勻。如果型(xing)(xing)(xing)坯(pi)(pi)(pi)(pi)同(tong)時(shi)結束(shu)自(zi)由吹(chui)(chui)脹(zhang)，就能(neng)得到壁厚(hou)(hou)完全均勻的(de)(de)制(zhi)(zhi)(zhi)(zhi)件(jian)。使型(xing)(xing)(xing)坯(pi)(pi)(pi)(pi)在(zai)(zai)真空負(fu)壓(ya)的(de)(de)拉力作(zuo)用下，先向吹(chui)(chui)脹(zhang)比較大部位發生(sheng)變(bian)(bian)(bian)形(xing)(xing)，然后注入壓(ya)縮空氣，改善型(xing)(xing)(xing)坯(pi)(pi)(pi)(pi)各處的(de)(de)吹(chui)(chui)脹(zhang)比，成(cheng)功(gong)得到壁厚(hou)(hou)較為(wei)(wei)(wei)均勻的(de)(de)制(zhi)(zhi)(zhi)(zhi)件(jian)。