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臥(wo)(wo)臥(wo)(wo)式(shi)擠(ji)(ji)壓(ya)(ya)(ya)機錠(ding)(ding)坯(pi)(pi)(pi)在填(tian)(tian)充擠(ji)(ji)壓(ya)(ya)(ya)階段的(de)(de)(de)(de)流(liu)動(dong)(dong)(dong)行(xing)(xing)為與(yu)(yu)立式(shi)的(de)(de)(de)(de)相(xiang)近(jin),但是(shi)臥(wo)(wo)式(shi)擠(ji)(ji)壓(ya)(ya)(ya)機上(shang)錠(ding)(ding)坯(pi)(pi)(pi)在裝人擠(ji)(ji)壓(ya)(ya)(ya)筒內(nei)由于自重必然與(yu)(yu)擠(ji)(ji)壓(ya)(ya)(ya)筒產生(sheng)面(mian)接觸(chu),并(bing)隨填(tian)(tian)充過(guo)程的(de)(de)(de)(de)繼續,錠(ding)(ding)坯(pi)(pi)(pi)與(yu)(yu)擠(ji)(ji)壓(ya)(ya)(ya)筒接觸(chu)面(mian)越來越大,工(gong)業(ye)鋁型材填(tian)(tian)充過(guo)程的(de)(de)(de)(de)變(bian)形(xing)(xing)除向(xiang)錠(ding)(ding)坯(pi)(pi)(pi)與(yu)(yu)擠(ji)(ji)壓(ya)(ya)(ya)筒間(jian)隙(xi)流(liu)動(dong)(dong)(dong)之(zhi)外,接觸(chu)面(mian)上(shang)會逐漸(jian)產生(sheng)沿(yan)錠(ding)(ding)坯(pi)(pi)(pi)周向(xiang)的(de)(de)(de)(de)流(liu)動(dong)(dong)(dong)趨勢。當錠(ding)(ding)坯(pi)(pi)(pi)原始(shi)長度與(yu)(yu)直徑(jing)之(zhi)比小(xiao)(xiao)(xiao)于4:1,即鐓粗比在合理范圍內(nei)時(shi),錠(ding)(ding)坯(pi)(pi)(pi)在填(tian)(tian)充階段的(de)(de)(de)(de)流(liu)動(dong)(dong)(dong)過(guo)程在軸向(xiang)壓(ya)(ya)(ya)力作(zuo)用下首(shou)先形(xing)(xing)成(cheng)單鼓形(xing)(xing),金(jin)(jin)屬(shu)向(xiang)錠(ding)(ding)坯(pi)(pi)(pi)與(yu)(yu)擠(ji)(ji)壓(ya)(ya)(ya)筒內(nei)壁(bi)間(jian)隙(xi)流(liu)動(dong)(dong)(dong)的(de)(de)(de)(de)同時(shi)有一小(xiao)(xiao)(xiao)部(bu)分金(jin)(jin)屬(shu)流(liu)向(xiang)模孔,隨著填(tian)(tian)充過(guo)程的(de)(de)(de)(de)進行(xing)(xing),前(qian)端(duan)(duan)面(mian)圓(yuan)周與(yu)(yu)模具接觸(chu)的(de)(de)(de)(de)金(jin)(jin)屬(shu)逐漸(jian)轉(zhuan)移到(dao)與(yu)(yu)工(gong)作(zuo)帶相(xiang)接觸(chu)的(de)(de)(de)(de)表(biao)面(mian)上(shang),形(xing)(xing)成(cheng)前(qian)端(duan)(duan)面(mian)側翻(fan)現象。在進入平流(liu)擠(ji)(ji)壓(ya)(ya)(ya)階段后,側翻(fan)的(de)(de)(de)(de)金(jin)(jin)屬(shu)成(cheng)為制品頭部(bu)的(de)(de)(de)(de)側表(biao)面(mian),工(gong)業(ye)鋁型材由于填(tian)(tian)充初始(shi)階段頭端(duan)(duan)外圓(yuan)周金(jin)(jin)屬(shu)的(de)(de)(de)(de)流(liu)動(dong)(dong)(dong)特點,導致(zhi)此階段錠(ding)(ding)坯(pi)(pi)(pi)頭端(duan)(duan)面(mian)金(jin)(jin)屬(shu)受到(dao)徑(jing)向(xiang)附加拉應力的(de)(de)(de)(de)作(zuo)用。當擠(ji)(ji)壓(ya)(ya)(ya)比較小(xiao)(xiao)(xiao)時(shi),在附加拉應力的(de)(de)(de)(de)作(zuo)用下制品前(qian)端(duan)(duan)易產生(sheng)開裂。
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