浙江至德鋼業有限公司為了減少不銹鋼管坯(pi)料與工模具接觸表面的溫降，有利于玻璃潤滑劑的軟化，提高潤滑效果，降低工模具表面熱沖擊引起的溫度應力，提高工模具的使用壽命，擠壓工模具使用前應進行預熱，其預熱溫度與擠壓材料和工模具的材質有關。擠壓不銹鋼管和型材時，工模具的預熱溫度見表2-25。

 美(mei)國PMAC公司的(de)2500噸擠壓(ya)(ya)(ya)機推薦的(de)預熱(re)(re)(re)溫(wen)度如下：工具鋼制作的(de)擠壓(ya)(ya)(ya)模(mo)和穿(chuan)孔頭為200℃，擠壓(ya)(ya)(ya)芯棒為250~320℃，擠壓(ya)(ya)(ya)筒為260~320℃，穿(chuan)孔筒為360~370℃。擠壓(ya)(ya)(ya)模(mo)、擠壓(ya)(ya)(ya)墊、芯棒等小(xiao)型工模(mo)具的(de)預熱(re)(re)(re)一般采用(yong)箱式電(dian)爐。擠壓(ya)(ya)(ya)筒的(de)預熱(re)(re)(re)主要有電(dian)阻加熱(re)(re)(re)和感(gan)(gan)應(ying)加熱(re)(re)(re)兩種。感(gan)(gan)應(ying)加熱(re)(re)(re)是將感(gan)(gan)應(ying)線圈(quan)放入擠壓(ya)(ya)(ya)筒內進行加熱(re)(re)(re)，加熱(re)(re)(re)時熱(re)(re)(re)流由(you)內襯(chen)向外傳導，擠壓(ya)(ya)(ya)簡內的(de)溫(wen)度分(fen)布(bu)較電(dian)阻加熱(re)(re)(re)合(he)(he)理（圖(tu)2-41),因為內襯(chen)、中(zhong)和外套之間(jian)的(de)過盈(ying)配合(he)(he)應(ying)力不會降低，但感(gan)(gan)應(ying)加熱(re)(re)(re)時操作不便，感(gan)(gan)應(ying)圈(quan)易損(sun)壞，所以目前主要還是采用(yong)電(dian)阻加熱(re)(re)(re)。

 在(zai)(zai)正常擠(ji)(ji)(ji)(ji)壓(ya)(ya)生產不(bu)銹鋼管(guan)過程(cheng)(cheng)中，擠(ji)(ji)(ji)(ji)壓(ya)(ya)工(gong)(gong)(gong)模(mo)(mo)具(ju)(ju)連續使(shi)(shi)(shi)用(yong)(yong)時(shi)，溫(wen)(wen)(wen)度將會(hui)逐漸升高(gao)，而(er)(er)引(yin)起工(gong)(gong)(gong)模(mo)(mo)具(ju)(ju)材質(zhi)高(gao)溫(wen)(wen)(wen)回火(huo)，降低了紅硬性，導致工(gong)(gong)(gong)模(mo)(mo)具(ju)(ju)產生變(bian)形而(er)(er)影響擠(ji)(ji)(ji)(ji)壓(ya)(ya)過程(cheng)(cheng)的(de)(de)順利進(jin)行。如擠(ji)(ji)(ji)(ji)壓(ya)(ya)墊(dian)的(de)(de)使(shi)(shi)(shi)用(yong)(yong)溫(wen)(wen)(wen)度過高(gao)，因(yin)熱(re)膨脹(zhang)過大產生變(bian)形而(er)(er)引(yin)起擠(ji)(ji)(ji)(ji)壓(ya)(ya)墊(dian)卡在(zai)(zai)擠(ji)(ji)(ji)(ji)壓(ya)(ya)筒(tong)(tong)內(nei)(nei)(nei)。為此，擠(ji)(ji)(ji)(ji)壓(ya)(ya)工(gong)(gong)(gong)模(mo)(mo)具(ju)(ju)在(zai)(zai)使(shi)(shi)(shi)用(yong)(yong)過程(cheng)(cheng)中又(you)需要進(jin)行必(bi)要的(de)(de)冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)卻(que)(que)，使(shi)(shi)(shi)其保持(chi)在(zai)(zai)所要求的(de)(de)溫(wen)(wen)(wen)度范圍內(nei)(nei)(nei)工(gong)(gong)(gong)作。對于外(wai)(wai)套內(nei)(nei)(nei)襯(chen)(chen)擠(ji)(ji)(ji)(ji)壓(ya)(ya)墊(dian)，擠(ji)(ji)(ji)(ji)壓(ya)(ya)模(mo)(mo)和小直(zhi)徑的(de)(de)芯(xin)棒一(yi)般(ban)可以(yi)采用(yong)(yong)3~4個(ge)循環(huan)(huan)輪(lun)流使(shi)(shi)(shi)用(yong)(yong)，必(bi)要時(shi)也(ye)可以(yi)在(zai)(zai)擠(ji)(ji)(ji)(ji)壓(ya)(ya)結束后進(jin)行水(shui)冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)或噴水(shui)冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)卻(que)(que)。對于擠(ji)(ji)(ji)(ji)壓(ya)(ya)筒(tong)(tong)和大直(zhi)徑的(de)(de)芯(xin)棒等大型(xing)工(gong)(gong)(gong)模(mo)(mo)具(ju)(ju)，在(zai)(zai)使(shi)(shi)(shi)用(yong)(yong)過程(cheng)(cheng)中吸熱(re)量大，更換又(you)不(bu)方便，故(gu)只(zhi)能采用(yong)(yong)專門(men)的(de)(de)冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)卻(que)(que)裝置(zhi)來進(jin)行冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)卻(que)(que)。如擠(ji)(ji)(ji)(ji)壓(ya)(ya)筒(tong)(tong)的(de)(de)冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)卻(que)(que)方式(shi)有(you)(you)內(nei)(nei)(nei)部通(tong)水(shui)冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)卻(que)(que)（內(nei)(nei)(nei)冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)式(shi)）和內(nei)(nei)(nei)襯(chen)(chen)噴水(shui)冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)卻(que)(que)（外(wai)(wai)冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)式(shi)）兩種。內(nei)(nei)(nei)冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)式(shi)（圖(tu)2-42)是在(zai)(zai)中襯(chen)(chen)內(nei)(nei)(nei)孔表面加工(gong)(gong)(gong)有(you)(you)螺旋形冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)卻(que)(que)槽(cao)，當(dang)擠(ji)(ji)(ji)(ji)壓(ya)(ya)筒(tong)(tong)溫(wen)(wen)(wen)度過高(gao)時(shi)，通(tong)入水(shui)溫(wen)(wen)(wen)不(bu)低于60~65℃的(de)(de)冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)卻(que)(que)水(shui)，以(yi)防止(zhi)過冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)引(yin)起裂紋，設有(you)(you)電(dian)加熱(re)器與(yu)水(shui)冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)卻(que)(que)裝置(zhi)的(de)(de)擠(ji)(ji)(ji)(ji)壓(ya)(ya)筒(tong)(tong)，如圖(tu)2-43所示；外(wai)(wai)冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)式(shi)是當(dang)擠(ji)(ji)(ji)(ji)壓(ya)(ya)循環(huan)(huan)結束時(shi)，采用(yong)(yong)環(huan)(huan)狀噴嘴(zui)在(zai)(zai)擠(ji)(ji)(ji)(ji)壓(ya)(ya)筒(tong)(tong)一(yi)端向筒(tong)(tong)內(nei)(nei)(nei)噴入壓(ya)(ya)力水(shui)冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)卻(que)(que)，這種方法比較簡單，但內(nei)(nei)(nei)襯(chen)(chen)的(de)(de)材質(zhi)要具(ju)(ju)有(you)(you)良(liang)好的(de)(de)耐急冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)急熱(re)性能。擠(ji)(ji)(ji)(ji)壓(ya)(ya)芯(xin)棒的(de)(de)冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)卻(que)(que)也(ye)有(you)(you)內(nei)(nei)(nei)冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)式(shi)和外(wai)(wai)冷(leng)(leng)(leng)(leng)(leng)(leng)(leng)式(shi)兩種（圖(tu)2-44)。