冷彎成型產(chan)品在生產(chan)加工(gong)時一定要注意產(chan)品的彈(dan)性變形和(he)在成型過(guo)程中形成的張(zhang)力，主要特點如(ru)下：
1. 產(chan)品的(de)彈(dan)性變形
冷(leng)彎(wan)產品質(zhi)量很大程度上取決于冷(leng)彎(wan)成(cheng)型(xing)機(ji)的(de)精度。欲正(zheng)確(que)調整冷(leng)彎(wan)成(cheng)型(xing)機(ji)，必須(xu)要預先確(que)定金屬對(dui)輥(gun)(gun)的(de)壓(ya)力與輥(gun)(gun)縫之間的(de)變(bian)化關系，即(ji)彈(dan)(dan)(dan)(dan)性(xing)(xing)(xing)(xing)(xing)變(bian)形(xing)(xing)情(qing)況。成(cheng)型(xing)機(ji)的(de)彈(dan)(dan)(dan)(dan)性(xing)(xing)(xing)(xing)(xing)變(bian)形(xing)(xing)由工作輥(gun)(gun)、軸承及軸承座(zuo)、機(ji)架(jia)牌坊、壓(ya)下裝置等的(de)彈(dan)(dan)(dan)(dan)性(xing)(xing)(xing)(xing)(xing)變(bian)形(xing)(xing)和(he)安裝間隙組(zu)成(cheng)。研(yan)究表明(ming)，當總(zong)負(fu)載(zai)不(bu)大時，軋輥(gun)(gun)彈(dan)(dan)(dan)(dan)性(xing)(xing)(xing)(xing)(xing)變(bian)形(xing)(xing)僅占總(zong)彈(dan)(dan)(dan)(dan)性(xing)(xing)(xing)(xing)(xing)變(bian)形(xing)(xing)的(de)25%;而當載(zai)荷大時（達200kN),成(cheng)型(xing)輥(gun)(gun)彈(dan)(dan)(dan)(dan)性(xing)(xing)(xing)(xing)(xing)變(bian)形(xing)(xing)占總(zong)彈(dan)(dan)(dan)(dan)性(xing)(xing)(xing)(xing)(xing)變(bian)形(xing)(xing)的(de)70%。可見成(cheng)型(xing)輥(gun)(gun)的(de)彈(dan)(dan)(dan)(dan)性(xing)(xing)(xing)(xing)(xing)變(bian)形(xing)(xing)是成(cheng)型(xing)機(ji)彈(dan)(dan)(dan)(dan)性(xing)(xing)(xing)(xing)(xing)變(bian)形(xing)(xing)中的(de)主要部(bu)分。
生產實際及理(li)論計算表明，對于（1~4)mm×(400~1500)mm冷(leng)(leng)彎(wan)(wan)成型機，當(dang)冷(leng)(leng)彎(wan)(wan)集中載荷為200kN時(shi)，成型輥彈性變(bian)形達1.49mm.
成型機彈(dan)(dan)(dan)性變(bian)(bian)形(xing)對(dui)產品質(zhi)量(liang)(liang)的(de)影響可在成型輥(gun)孔型設(she)計中設(she)置輥(gun)縫時加以(yi)補償。它應等于(yu)金屬(shu)料(liao)(liao)厚(hou)度(du)與彈(dan)(dan)(dan)跳間距差值(zhi)。另外(wai)，冷(leng)彎生(sheng)(sheng)產實(shi)踐及(ji)理論研究表明，冷(leng)彎過程中除塑(su)性變(bian)(bian)形(xing)外(wai)，還(huan)存在彈(dan)(dan)(dan)性變(bian)(bian)形(xing)和彈(dan)(dan)(dan)塑(su)性變(bian)(bian)形(xing)共存的(de)狀(zhuang)況，當金屬(shu)移(yi)出(chu)孔型后(hou)，彎曲角要發生(sheng)(sheng)變(bian)(bian)化。如圖5-16(a)所示，設(she)計彎曲角為β,移(yi)出(chu)孔型后(hou)會回(hui)(hui)(hui)彈(dan)(dan)(dan)γ角度(du)，因(yin)此欲得精確形(xing)狀(zhuang)產品，成品道次應考慮過量(liang)(liang)彎角度(du)，以(yi)彌補回(hui)(hui)(hui)彈(dan)(dan)(dan)，見圖5-16(b).實(shi)踐證明，材料(liao)(liao)彈(dan)(dan)(dan)性極限越(yue)(yue)(yue)(yue)大(da)，回(hui)(hui)(hui)彈(dan)(dan)(dan)就越(yue)(yue)(yue)(yue)大(da)，材料(liao)(liao)越(yue)(yue)(yue)(yue)厚(hou)回(hui)(hui)(hui)彈(dan)(dan)(dan)越(yue)(yue)(yue)(yue)大(da)，彎曲臂越(yue)(yue)(yue)(yue)長回(hui)(hui)(hui)彈(dan)(dan)(dan)越(yue)(yue)(yue)(yue)大(da)，彎曲角越(yue)(yue)(yue)(yue)多回(hui)(hui)(hui)彈(dan)(dan)(dan)也會越(yue)(yue)(yue)(yue)大(da)。
此外工藝過程(cheng)的不(bu)(bu)同，材(cai)料(liao)彎曲時應力(li)、應變狀態不(bu)(bu)同，回彈量(liang)亦不(bu)(bu)同。一般(ban)認(ren)為(wei)，對(dui)于簡(jian)單斷面(mian)冷(leng)彎型(xing)鋼，由于彎折處及邊部(bu)存(cun)在拉應力(li)，回彈較小，所以一般(ban)可不(bu)(bu)取過量(liang)彎角度，或(huo)者僅考慮30'~1°即可。而對(dui)于波紋型(xing)鋼，中心波要(yao)考慮向內過彎1°,邊波要(yao)大30'。
2. 機組張力
在(zai)冷彎成(cheng)(cheng)型機組(zu)上，帶鋼(gang)前(qian)進的驅(qu)動力(li)(li)是通過驅(qu)動輥和帶鋼(gang)之(zhi)間(jian)的摩擦力(li)(li)傳遞的。為了在(zai)成(cheng)(cheng)型過程(cheng)中形成(cheng)(cheng)張力(li)(li)、不(bu)產(chan)生堆鋼(gang)、使成(cheng)(cheng)型后(hou)(hou)型鋼(gang)平直，成(cheng)(cheng)型輥的平均輥徑要加工成(cheng)(cheng)從第一(yi)架(jia)開始(shi)逐漸增(zeng)大(da)的趨勢，即(ji)Dn+1稍大(da)于(yu)Dn,使后(hou)(hou)一(yi)架(jia)對前(qian)一(yi)架(jia)有一(yi)個拉(la)伸作用。由(you)于(yu)直徑增(zeng)加其線速度就會(hui)增(zeng)加，因此在(zai)架(jia)次之(zhi)間(jian)就形成(cheng)(cheng)了張力(li)(li)，從而帶鋼(gang)能(neng)平直地運行。
Dn+1=(1.005~1.010)Dn
式(shi)中 Dn 第n架成型輥平均直徑；
Dn+1 第n+1架成型輥平均直徑。
