旋(xuan)(xuan)壓成(cheng)型是一種(zhong)歷史悠久的(de)(de)工(gong)(gong)藝方法(fa)，我(wo)國古時在10世(shi)紀(ji)就有了(le)這(zhe)種(zhong)成(cheng)型方法(fa)，后來于14世(shi)紀(ji)才傳入歐洲(zhou)。用(yong)旋(xuan)(xuan)壓成(cheng)型方法(fa)可制造各種(zhong)不同(tong)形狀的(de)(de)旋(xuan)(xuan)轉面工(gong)(gong)件(jian)，如發動機罩、螺旋(xuan)(xuan)槳(jiang)槳(jiang)帽等。圖4-18是采用(yong)旋(xuan)(xuan)壓成(cheng)型工(gong)(gong)藝加工(gong)(gong)的(de)(de)典型器件(jian)的(de)(de)示(shi)意圖。


圖 18.jpg


1. 旋壓成型原理


  旋(xuan)(xuan)壓(ya)成型用(yong)的設備(bei)類似于(yu)車(che)床(chuang)或(huo)由車(che)床(chuang)改裝而成的，但最(zui)新發展有數控(kong)旋(xuan)(xuan)壓(ya)床(chuang)。旋(xuan)(xuan)壓(ya)床(chuang)的工作原理如圖4-19所(suo)示。用(yong)機(ji)床(chuang)尾頂座2通過(guo)頂塊3將(jiang)平板毛(mao)坯1壓(ya)緊于(yu)旋(xuan)(xuan)壓(ya)模4上，毛(mao)坯連同模具(ju)一起(qi)旋(xuan)(xuan)轉，操(cao)作者(zhe)用(yong)手操(cao)作旋(xuan)(xuan)壓(ya)棒，將(jiang)毛(mao)坯順次壓(ya)向(xiang)旋(xuan)(xuan)壓(ya)模，這時毛(mao)坯發生周向(xiang)收縮和徑向(xiang)延伸變形(xing)(xing)，最(zui)后旋(xuan)(xuan)壓(ya)成型為(wei)要求的形(xing)(xing)狀。


圖 19.jpg


2. 旋壓(ya)注(zhu)意事項


  旋(xuan)(xuan)(xuan)壓(ya)成(cheng)(cheng)型(xing)過(guo)程(cheng)的主要問(wen)題是起(qi)皺和(he)局(ju)部(bu)(bu)變(bian)薄以(yi)及(ji)拉(la)裂。如圖(tu)4-19所示的旋(xuan)(xuan)(xuan)壓(ya)壓(ya)延過(guo)程(cheng)，凸(tu)(tu)緣周(zhou)邊(bian)(bian)(bian)起(qi)皺決定于收縮變(bian)形(xing)程(cheng)度（即(ji)工(gong)(gong)(gong)件直(zhi)(zhi)徑(jing)和(he)毛(mao)坯(pi)直(zhi)(zhi)徑(jing)之比值(zhi)）、毛(mao)坯(pi)的穩(wen)(wen)定性(xing)（如l./D.數(shu)值(zhi)）、毛(mao)料(liao)轉(zhuan)速(su)以(yi)及(ji)操(cao)(cao)(cao)作者(zhe)的經驗。提高毛(mao)坯(pi)的轉(zhuan)速(su)會增(zeng)(zeng)加毛(mao)坯(pi)凸(tu)(tu)緣的穩(wen)(wen)定性(xing)，但由(you)手工(gong)(gong)(gong)操(cao)(cao)(cao)作不能保證均勻(yun)的縱向送(song)進，會造(zao)成(cheng)(cheng)局(ju)部(bu)(bu)過(guo)度輾薄，一般成(cheng)(cheng)型(xing)加工(gong)(gong)(gong)所用(yong)的轉(zhuan)速(su)多(duo)在200~600r/min的范(fan)圍內。為了(le)防(fang)止起(qi)皺和(he)旋(xuan)(xuan)(xuan)壓(ya)模(mo)(mo)圓(yuan)角處材(cai)料(liao)變(bian)薄或(huo)拉(la)裂，操(cao)(cao)(cao)作順序(xu)應按如下(xia)進行：首次操(cao)(cao)(cao)作時將(jiang)凸(tu)(tu)模(mo)(mo)圓(yuan)角處材(cai)料(liao)趕形(xing)貼模(mo)(mo)形(xing)成(cheng)(cheng)帽形(xing)件；第二步操(cao)(cao)(cao)作時將(jiang)帽形(xing)件凸(tu)(tu)緣趕形(xing)成(cheng)(cheng)圓(yuan)錐面以(yi)增(zeng)(zeng)加這部(bu)(bu)分材(cai)料(liao)的剛度；第三(san)(san)步操(cao)(cao)(cao)作（防(fang)起(qi)皺）是旋(xuan)(xuan)(xuan)壓(ya)棒(bang)從毛(mao)料(liao)周(zhou)邊(bian)(bian)(bian)向凸(tu)(tu)模(mo)(mo)圓(yuan)角處趕并使毛(mao)料(liao)向凸(tu)(tu)模(mo)(mo)靠攏。以(yi)后(hou)(hou)的操(cao)(cao)(cao)作是重(zhong)復上述第二、三(san)(san)步驟。逐步地將(jiang)材(cai)料(liao)旋(xuan)(xuan)(xuan)壓(ya)至貼模(mo)(mo)為止，最后(hou)(hou)再加以(yi)修(xiu)整(zheng)趕形(xing)和(he)工(gong)(gong)(gong)件切(qie)邊(bian)(bian)(bian)。因為旋(xuan)(xuan)(xuan)壓(ya)過(guo)程(cheng)的變(bian)形(xing)情況極其(qi)復雜，多(duo)半(ban)又(you)是手工(gong)(gong)(gong)操(cao)(cao)(cao)作，故成(cheng)(cheng)型(xing)之成(cheng)(cheng)敗與操(cao)(cao)(cao)作者(zhe)的經驗有直(zhi)(zhi)接的關系(xi)。


  旋壓還可用于對(dui)工(gong)件(jian)進行縮口(kou)、卷(juan)邊、擴口(kou)等項成型加工(gong)作業(ye)。


3. 旋壓(ya)的優缺點


  旋(xuan)壓的缺(que)(que)點是零(ling)件(jian)變薄(bo)量較(jiao)大，勞動強度較(jiao)大，對操作技術水平要(yao)(yao)求(qiu)較(jiao)高，而勞動生產率低等。旋(xuan)壓工(gong)作雖有這(zhe)些(xie)缺(que)(que)點，但是由于(yu)旋(xuan)壓模(mo)具簡單(dan)，特別能適(shi)應于(yu)加工(gong)某(mou)些(xie)比(bi)較(jiao)復雜的旋(xuan)轉面零(ling)件(jian)，所以至今還是航空(kong)工(gong)業中不(bu)可(ke)缺(que)(que)少的成型工(gong)藝方法。旋(xuan)壓設備的改進和(he)旋(xuan)壓過程的自動化能夠克服上述的主要(yao)(yao)缺(que)(que)點，并且使(shi)旋(xuan)壓工(gong)藝得(de)到新的發展(zhan)。


4. 旋壓模


  旋(xuan)壓模一般(ban)用(yong)鑄鐵、鋼和銅合(he)金制(zhi)造。有時在試制(zhi)時，也可用(yong)硬(ying)木(mu)制(zhi)造。旋(xuan)壓模按反(fan)切內樣板進(jin)行加工，零件按反(fan)切外樣板進(jin)行檢驗。


  對于變形程(cheng)度較大的工(gong)件可用一套模具(ju)經(jing)多次旋壓成型并經(jing)中間退火工(gong)序，有(you)時還可增加模具(ju)套數，即采(cai)用中間過渡模等方(fang)法解決。