冷彎(wan)成型產(chan)品在生產(chan)加工時(shi)一定要(yao)(yao)注意產(chan)品的(de)彈性變形(xing)和在成型過程中(zhong)形(xing)成的(de)張力，主(zhu)要(yao)(yao)特點如下：
1. 產(chan)品的(de)彈(dan)性變(bian)形(xing)
冷彎產品質量很大(da)程(cheng)度上取決于冷彎成(cheng)(cheng)(cheng)型(xing)機(ji)的(de)(de)(de)精(jing)度。欲正確調整冷彎成(cheng)(cheng)(cheng)型(xing)機(ji)，必須要預(yu)先確定(ding)金屬對輥(gun)的(de)(de)(de)壓(ya)力與輥(gun)縫之(zhi)間的(de)(de)(de)變(bian)(bian)化(hua)關系，即彈(dan)(dan)性(xing)變(bian)(bian)形(xing)情況。成(cheng)(cheng)(cheng)型(xing)機(ji)的(de)(de)(de)彈(dan)(dan)性(xing)變(bian)(bian)形(xing)由工(gong)作輥(gun)、軸承及軸承座、機(ji)架牌坊、壓(ya)下裝置等的(de)(de)(de)彈(dan)(dan)性(xing)變(bian)(bian)形(xing)和安裝間隙組(zu)成(cheng)(cheng)(cheng)。研究表(biao)明(ming)，當總(zong)負載不大(da)時，軋輥(gun)彈(dan)(dan)性(xing)變(bian)(bian)形(xing)僅占總(zong)彈(dan)(dan)性(xing)變(bian)(bian)形(xing)的(de)(de)(de)25%;而(er)當載荷大(da)時（達200kN),成(cheng)(cheng)(cheng)型(xing)輥(gun)彈(dan)(dan)性(xing)變(bian)(bian)形(xing)占總(zong)彈(dan)(dan)性(xing)變(bian)(bian)形(xing)的(de)(de)(de)70%。可見成(cheng)(cheng)(cheng)型(xing)輥(gun)的(de)(de)(de)彈(dan)(dan)性(xing)變(bian)(bian)形(xing)是(shi)成(cheng)(cheng)(cheng)型(xing)機(ji)彈(dan)(dan)性(xing)變(bian)(bian)形(xing)中(zhong)的(de)(de)(de)主要部分。
生產實際及理論計(ji)算表明，對于（1~4)mm×(400~1500)mm冷彎成(cheng)(cheng)型機，當(dang)冷彎集中載(zai)荷為(wei)200kN時，成(cheng)(cheng)型輥(gun)彈性(xing)變形達1.49mm.
成(cheng)型(xing)(xing)(xing)機彈(dan)(dan)性(xing)(xing)變(bian)形(xing)(xing)對產品質量(liang)的(de)影響(xiang)可在成(cheng)型(xing)(xing)(xing)輥孔型(xing)(xing)(xing)設計(ji)中(zhong)(zhong)設置輥縫時(shi)加以補償。它應(ying)等于金屬料厚度與彈(dan)(dan)跳(tiao)間距差值(zhi)。另(ling)外，冷(leng)彎(wan)(wan)(wan)生產實踐及理論研究表明，冷(leng)彎(wan)(wan)(wan)過程中(zhong)(zhong)除塑性(xing)(xing)變(bian)形(xing)(xing)外，還存在彈(dan)(dan)性(xing)(xing)變(bian)形(xing)(xing)和彈(dan)(dan)塑性(xing)(xing)變(bian)形(xing)(xing)共存的(de)狀況(kuang)，當金屬移出(chu)孔型(xing)(xing)(xing)后，彎(wan)(wan)(wan)曲角(jiao)要發生變(bian)化。如圖5-16(a)所示，設計(ji)彎(wan)(wan)(wan)曲角(jiao)為(wei)β,移出(chu)孔型(xing)(xing)(xing)后會回(hui)彈(dan)(dan)γ角(jiao)度，因此欲得精確形(xing)(xing)狀產品，成(cheng)品道(dao)次應(ying)考慮過量(liang)彎(wan)(wan)(wan)角(jiao)度，以彌補回(hui)彈(dan)(dan)，見圖5-16(b).實踐證明，材(cai)料彈(dan)(dan)性(xing)(xing)極(ji)限越(yue)(yue)大，回(hui)彈(dan)(dan)就越(yue)(yue)大，材(cai)料越(yue)(yue)厚回(hui)彈(dan)(dan)越(yue)(yue)大，彎(wan)(wan)(wan)曲臂越(yue)(yue)長回(hui)彈(dan)(dan)越(yue)(yue)大，彎(wan)(wan)(wan)曲角(jiao)越(yue)(yue)多回(hui)彈(dan)(dan)也會越(yue)(yue)大。
此外(wai)工(gong)藝(yi)過程的不(bu)同(tong)(tong)(tong)，材料彎曲時應(ying)力、應(ying)變狀態(tai)不(bu)同(tong)(tong)(tong)，回彈量亦不(bu)同(tong)(tong)(tong)。一般認為，對于簡(jian)單斷面(mian)冷彎型鋼，由于彎折(zhe)處及邊(bian)部存在拉應(ying)力，回彈較小(xiao)，所(suo)以一般可不(bu)取過量彎角度，或者(zhe)僅考慮(lv)30'~1°即可。而對于波紋型鋼，中心波要(yao)考慮(lv)向內(nei)過彎1°,邊(bian)波要(yao)大30'。
2. 機(ji)組(zu)張力
在(zai)冷彎成型(xing)機(ji)組(zu)上，帶(dai)鋼(gang)(gang)(gang)前(qian)進的(de)驅(qu)動力(li)是通(tong)過驅(qu)動輥(gun)和帶(dai)鋼(gang)(gang)(gang)之間的(de)摩擦(ca)力(li)傳遞的(de)。為了在(zai)成型(xing)過程中(zhong)形(xing)成張(zhang)力(li)、不產生堆鋼(gang)(gang)(gang)、使(shi)成型(xing)后(hou)型(xing)鋼(gang)(gang)(gang)平(ping)直(zhi)，成型(xing)輥(gun)的(de)平(ping)均輥(gun)徑要加工成從第一(yi)架(jia)開始(shi)逐漸增大的(de)趨(qu)勢，即(ji)Dn+1稍大于Dn,使(shi)后(hou)一(yi)架(jia)對(dui)前(qian)一(yi)架(jia)有一(yi)個拉(la)伸作用(yong)。由(you)于直(zhi)徑增加其線速度就(jiu)會增加，因此在(zai)架(jia)次(ci)之間就(jiu)形(xing)成了張(zhang)力(li)，從而(er)帶(dai)鋼(gang)(gang)(gang)能平(ping)直(zhi)地運行。
Dn+1=(1.005~1.010)Dn
式中 Dn 第n架(jia)成型輥平(ping)均直(zhi)徑；
Dn+1 第n+1架成型輥平均直徑。
