冷(leng)彎(wan)成型(xing)產(chan)(chan)品在生產(chan)(chan)加工時一定要注意產(chan)(chan)品的彈性(xing)變形和在成型(xing)過程中形成的張力，主要特點(dian)如下：
1. 產品(pin)的彈性變(bian)形
冷彎(wan)產(chan)品質量很(hen)大程度(du)上取決于(yu)冷彎(wan)成(cheng)型機的(de)(de)(de)(de)(de)精度(du)。欲正確調整冷彎(wan)成(cheng)型機，必須要(yao)預先(xian)確定(ding)金屬對(dui)輥(gun)(gun)的(de)(de)(de)(de)(de)壓力與輥(gun)(gun)縫(feng)之(zhi)間的(de)(de)(de)(de)(de)變(bian)(bian)(bian)化(hua)關系(xi)，即彈(dan)(dan)性(xing)(xing)(xing)變(bian)(bian)(bian)形(xing)情況。成(cheng)型機的(de)(de)(de)(de)(de)彈(dan)(dan)性(xing)(xing)(xing)變(bian)(bian)(bian)形(xing)由工作輥(gun)(gun)、軸承及軸承座、機架牌坊(fang)、壓下(xia)裝置(zhi)等的(de)(de)(de)(de)(de)彈(dan)(dan)性(xing)(xing)(xing)變(bian)(bian)(bian)形(xing)和安裝間隙(xi)組成(cheng)。研究表(biao)明，當總負載(zai)不大時，軋(ya)輥(gun)(gun)彈(dan)(dan)性(xing)(xing)(xing)變(bian)(bian)(bian)形(xing)僅占總彈(dan)(dan)性(xing)(xing)(xing)變(bian)(bian)(bian)形(xing)的(de)(de)(de)(de)(de)25%;而當載(zai)荷大時（達200kN),成(cheng)型輥(gun)(gun)彈(dan)(dan)性(xing)(xing)(xing)變(bian)(bian)(bian)形(xing)占總彈(dan)(dan)性(xing)(xing)(xing)變(bian)(bian)(bian)形(xing)的(de)(de)(de)(de)(de)70%。可見成(cheng)型輥(gun)(gun)的(de)(de)(de)(de)(de)彈(dan)(dan)性(xing)(xing)(xing)變(bian)(bian)(bian)形(xing)是成(cheng)型機彈(dan)(dan)性(xing)(xing)(xing)變(bian)(bian)(bian)形(xing)中的(de)(de)(de)(de)(de)主要(yao)部分。
生產實(shi)際及(ji)理論計算表明，對于（1~4)mm×(400~1500)mm冷彎成型(xing)機，當冷彎集中載荷為200kN時，成型(xing)輥彈性(xing)變(bian)形達1.49mm.
成(cheng)(cheng)型(xing)(xing)(xing)機(ji)彈(dan)性(xing)變形(xing)(xing)對產品質量(liang)的影響可在成(cheng)(cheng)型(xing)(xing)(xing)輥孔型(xing)(xing)(xing)設(she)計中設(she)置輥縫時(shi)加以補償。它應等(deng)于金屬料厚(hou)度與彈(dan)跳間(jian)距差值。另(ling)外，冷彎(wan)生產實(shi)踐及理(li)論研(yan)究表明，冷彎(wan)過(guo)程中除塑(su)性(xing)變形(xing)(xing)外，還存在彈(dan)性(xing)變形(xing)(xing)和彈(dan)塑(su)性(xing)變形(xing)(xing)共存的狀(zhuang)況，當金屬移(yi)出(chu)孔型(xing)(xing)(xing)后(hou)，彎(wan)曲(qu)角(jiao)(jiao)要(yao)發生變化。如(ru)圖(tu)5-16(a)所示(shi)，設(she)計彎(wan)曲(qu)角(jiao)(jiao)為β,移(yi)出(chu)孔型(xing)(xing)(xing)后(hou)會回(hui)彈(dan)γ角(jiao)(jiao)度，因此欲(yu)得精確形(xing)(xing)狀(zhuang)產品，成(cheng)(cheng)品道次應考慮過(guo)量(liang)彎(wan)角(jiao)(jiao)度，以彌補回(hui)彈(dan)，見圖(tu)5-16(b).實(shi)踐證明，材料彈(dan)性(xing)極限越(yue)(yue)大，回(hui)彈(dan)就越(yue)(yue)大，材料越(yue)(yue)厚(hou)回(hui)彈(dan)越(yue)(yue)大，彎(wan)曲(qu)臂越(yue)(yue)長回(hui)彈(dan)越(yue)(yue)大，彎(wan)曲(qu)角(jiao)(jiao)越(yue)(yue)多回(hui)彈(dan)也會越(yue)(yue)大。
此外(wai)工藝過(guo)程的不(bu)同，材料彎(wan)(wan)曲時應(ying)力、應(ying)變狀態不(bu)同，回(hui)(hui)彈(dan)(dan)量亦不(bu)同。一(yi)般認為，對于簡單斷(duan)面冷(leng)彎(wan)(wan)型鋼(gang)，由(you)于彎(wan)(wan)折處及邊部存在拉(la)應(ying)力，回(hui)(hui)彈(dan)(dan)較小(xiao)，所以一(yi)般可不(bu)取過(guo)量彎(wan)(wan)角度，或者僅考慮(lv)30'~1°即可。而(er)對于波(bo)(bo)紋型鋼(gang)，中(zhong)心波(bo)(bo)要考慮(lv)向內過(guo)彎(wan)(wan)1°,邊波(bo)(bo)要大30'。
2. 機(ji)組張力
在(zai)冷彎成(cheng)(cheng)型(xing)(xing)機組上，帶(dai)鋼(gang)(gang)前(qian)進的驅動力(li)是通(tong)過驅動輥(gun)和(he)帶(dai)鋼(gang)(gang)之間(jian)(jian)的摩擦力(li)傳(chuan)遞的。為了(le)(le)在(zai)成(cheng)(cheng)型(xing)(xing)過程中形成(cheng)(cheng)張力(li)、不(bu)產生堆鋼(gang)(gang)、使(shi)成(cheng)(cheng)型(xing)(xing)后型(xing)(xing)鋼(gang)(gang)平直，成(cheng)(cheng)型(xing)(xing)輥(gun)的平均輥(gun)徑要加工成(cheng)(cheng)從第一(yi)架開始(shi)逐漸增大的趨勢，即Dn+1稍大于Dn,使(shi)后一(yi)架對前(qian)一(yi)架有一(yi)個拉伸作用。由于直徑增加其(qi)線速度就會增加，因此(ci)在(zai)架次之間(jian)(jian)就形成(cheng)(cheng)了(le)(le)張力(li)，從而帶(dai)鋼(gang)(gang)能(neng)平直地運(yun)行。
Dn+1=(1.005~1.010)Dn
式(shi)中 Dn 第n架成型輥平(ping)均直徑(jing)；
Dn+1 第n+1架成型輥平均直徑。
