將板、帶鋼在輥式冷(leng)彎成型機上，經若干架次相對旋轉的成型輥（水平輥、立輥、組合輥）連續彎曲變形以得到要求的形狀尺寸的冷彎型鋼的過程稱為輥式冷彎成型。輥式冷彎成型是金屬壓力加工工藝的一種，其成型過程如圖5-9所示。平板坯的特定部位經漸次彎曲成角度a2、a2、α3、···an,最后成為所要求的斷面。輥式冷彎成型與型鋼熱軋不同之處是，其各道次金屬橫截面積從理論上可視為不變。這種變形也不同于非穩態變形的沖壓成型，從一個角度彎至下一道的某一角度，在板坯全長上不是同時成型的，而是經過一個平緩過渡后，逐漸彎成需要的角度。

 輥(gun)(gun)(gun)式冷彎(wan)(wan)(wan)(wan)成型(xing)(xing)(xing)和普通(tong)軋(ya)(ya)(ya)(ya)制過(guo)(guo)(guo)(guo)(guo)程(cheng)(cheng)一(yi)(yi)樣，冷彎(wan)(wan)(wan)(wan)成型(xing)(xing)(xing)時(shi)帶坯(pi)(pi)任意斷面(mian)(mian)(mian)上(shang)的(de)(de)(de)金(jin)屬流動是穩(wen)定的(de)(de)(de)，不(bu)(bu)隨時(shi)間(jian)而(er)變(bian)(bian)(bian)化(hua)，相(xiang)鄰(lin)兩(liang)(liang)道次之間(jian)帶坯(pi)(pi)進(jin)入軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)位置，如圖5-10所示，彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)角(jiao)(jiao)由上(shang)一(yi)(yi)道次的(de)(de)(de)αn-1增(zeng)大(da)(da)到(dao)下一(yi)(yi)道次的(de)(de)(de)αn,彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)圓弧半徑由rn-1,減小為(wei)rn.由于板(ban)(ban)坯(pi)(pi)前(qian)(qian)端部(bu)上(shang)拾，彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)角(jiao)(jiao)增(zeng)大(da)(da)，而(er)產生(sheng)(sheng)(sheng)的(de)(de)(de)張力(li)作用(yong)(yong)于邊(bian)部(bu)，在(zai)相(xiang)對(dui)旋轉的(de)(de)(de)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)的(de)(de)(de)作用(yong)(yong)下，板(ban)(ban)帶坯(pi)(pi)沿軋(ya)(ya)(ya)(ya)制方向前(qian)(qian)進(jin)并實現(xian)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)變(bian)(bian)(bian)形(xing)(xing)。實現(xian)板(ban)(ban)坯(pi)(pi)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)變(bian)(bian)(bian)形(xing)(xing)的(de)(de)(de)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)工作部(bu)分(fen)(fen)稱(cheng)(cheng)為(wei)軋(ya)(ya)(ya)(ya)槽(cao)（輥(gun)(gun)(gun)槽(cao)），由兩(liang)(liang)個和兩(liang)(liang)個以上(shang)通(tong)過(guo)(guo)(guo)(guo)(guo)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)軸平(ping)面(mian)(mian)(mian)所構(gou)成的(de)(de)(de)軋(ya)(ya)(ya)(ya)槽(cao)斷面(mian)(mian)(mian)變(bian)(bian)(bian)形(xing)(xing)區(qu)稱(cheng)(cheng)為(wei)孔(kong)(kong)(kong)型(xing)(xing)(xing)。因(yin)此，輥(gun)(gun)(gun)式冷彎(wan)(wan)(wan)(wan)成型(xing)(xing)(xing)亦可視(shi)為(wei)板(ban)(ban)坯(pi)(pi)經若(ruo)干孔(kong)(kong)(kong)型(xing)(xing)(xing)實現(xian)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)的(de)(de)(de)穩(wen)態變(bian)(bian)(bian)形(xing)(xing)過(guo)(guo)(guo)(guo)(guo)程(cheng)(cheng)。從(cong)上(shang)一(yi)(yi)道輥(gun)(gun)(gun)軸平(ping)面(mian)(mian)(mian)（孔(kong)(kong)(kong)型(xing)(xing)(xing)）到(dao)下一(yi)(yi)道輥(gun)(gun)(gun)軸平(ping)面(mian)(mian)(mian)（孔(kong)(kong)(kong)型(xing)(xing)(xing)）間(jian)距(ju)離L稱(cheng)(cheng)為(wei)平(ping)緩(huan)過(guo)(guo)(guo)(guo)(guo)渡區(qu)長(chang)度。L的(de)(de)(de)大(da)(da)小與(yu)機架(jia)間(jian)距(ju)有關，L愈(yu)大(da)(da)變(bian)(bian)(bian)形(xing)(xing)愈(yu)緩(huan)和。而(er)平(ping)緩(huan)過(guo)(guo)(guo)(guo)(guo)渡區(qu)又可細分(fen)(fen)為(wei)L1和L2兩(liang)(liang)個區(qu)（見圖5-11).板(ban)(ban)坯(pi)(pi)從(cong)前(qian)(qian)道孔(kong)(kong)(kong)型(xing)(xing)(xing)（對(dui)應(ying)(ying)(ying)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)角(jiao)(jiao)an-1)進(jin)入下道孔(kong)(kong)(kong)型(xing)(xing)(xing)（對(dui)應(ying)(ying)(ying)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)角(jiao)(jiao)αn),開始時(shi)坯(pi)(pi)料(liao)前(qian)(qian)端部(bu)分(fen)(fen)與(yu)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)下軋(ya)(ya)(ya)(ya)槽(cao)接觸，在(zai)坯(pi)(pi)料(liao)中形(xing)(xing)成數值不(bu)(bu)大(da)(da)的(de)(de)(de)彈性(xing)應(ying)(ying)(ying)力(li)。軋(ya)(ya)(ya)(ya)件前(qian)(qian)行與(yu)上(shang)軋(ya)(ya)(ya)(ya)槽(cao)接觸，在(zai)上(shang)下軋(ya)(ya)(ya)(ya)槽(cao)作用(yong)(yong)下產生(sheng)(sheng)(sheng)塑性(xing)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)，即(ji)板(ban)(ban)坯(pi)(pi)在(zai)輥(gun)(gun)(gun)軸平(ping)面(mian)(mian)(mian)前(qian)(qian)（未(wei)通(tong)過(guo)(guo)(guo)(guo)(guo)an孔(kong)(kong)(kong)型(xing)(xing)(xing)）已開始了塑性(xing)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)變(bian)(bian)(bian)形(xing)(xing)，原來(lai)平(ping)直(zhi)的(de)(de)(de)邊(bian)部(bu)產生(sheng)(sheng)(sheng)縱(zong)向扭曲(qu)(qu)(qu)(qu)(qu)，形(xing)(xing)成復雜的(de)(de)(de)曲(qu)(qu)(qu)(qu)(qu)線表面(mian)(mian)(mian)。坯(pi)(pi)料(liao)的(de)(de)(de)橫截面(mian)(mian)(mian)形(xing)(xing)狀逐(zhu)漸按孔(kong)(kong)(kong)型(xing)(xing)(xing)輪廓形(xing)(xing)狀變(bian)(bian)(bian)化(hua)。彎(wan)(wan)(wan)(wan)折(zhe)處金(jin)屬連續(xu)經受彈性(xing)到(dao)彈塑性(xing)變(bian)(bian)(bian)形(xing)(xing)。隨彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)角(jiao)(jiao)增(zeng)大(da)(da)，彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)圓弧半徑減小，彎(wan)(wan)(wan)(wan)折(zhe)處切向正應(ying)(ying)(ying)力(li)和彎(wan)(wan)(wan)(wan)矩增(zeng)加，在(zai)板(ban)(ban)坯(pi)(pi)料(liao)前(qian)(qian)端已變(bian)(bian)(bian)形(xing)(xing)部(bu)分(fen)(fen)與(yu)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)壓緊軋(ya)(ya)(ya)(ya)件的(de)(de)(de)共同作用(yong)(yong)下，板(ban)(ban)坯(pi)(pi)邊(bian)部(bu)出現(xian)拉應(ying)(ying)(ying)力(li)，引起邊(bian)部(bu)拉伸，板(ban)(ban)坯(pi)(pi)通(tong)過(guo)(guo)(guo)(guo)(guo)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)軸平(ping)面(mian)(mian)(mian)之后(hou)（通(tong)過(guo)(guo)(guo)(guo)(guo)孔(kong)(kong)(kong)型(xing)(xing)(xing)后(hou)），原來(lai)產生(sheng)(sheng)(sheng)縱(zong)向扭曲(qu)(qu)(qu)(qu)(qu)的(de)(de)(de)邊(bian)部(bu)被拉平(ping)，輥(gun)(gun)(gun)軸平(ping)面(mian)(mian)(mian)前(qian)(qian)變(bian)(bian)(bian)形(xing)(xing)區(qu)長(chang)度不(bu)(bu)再增(zeng)加而(er)保持長(chang)度不(bu)(bu)變(bian)(bian)(bian)（L)。

 這是平緩過渡區第一階段，整個過程中彎曲角單方向增大（從（an-1增至an+Δan),見圖5-12,并且坯料中性層彎曲圓弧半徑從rn-1減小至rn.通過軸平面后，變形區長度仍有增加，形成平緩過渡區第二階段，彎曲角從an+Δan減小為αn.坯料前端出現彈性變形特征，內應力重新分布，第二階段長度不再增加（L2),在此長度范圍內整個橫截面上內應力彼此相等，呈現第一類殘應力特征。成型過程繼續下去，平緩過渡區保持形狀尺寸不變，其長度通常小于兩機架間距離。

 彎曲角變化呈S形，分為三段。在平緩過渡區任一位置上彎曲角大小可用下式表示.

坯料(liao)橫截面各個直線部分受(shou)縱向(xiang)拉伸(shen)或壓縮變(bian)(bian)形，與之相鄰的(de)曲(qu)線部分受(shou)彎曲(qu)變(bian)(bian)形，弄清板坯在相鄰兩道次(ci)間(jian)彎曲(qu)變(bian)(bian)形行為，對(dui)于(yu)制定成(cheng)型方案和設計孔型具有一定的(de)意義。

為(wei)將板帶材(cai)(cai)經(jing)連續輥彎(wan)(wan)變形加工成(cheng)(cheng)(cheng)合(he)格冷(leng)彎(wan)(wan)型鋼而進行的(de)成(cheng)(cheng)(cheng)型方法及工具的(de)設(she)計(ji)稱(cheng)為(wei)冷(leng)彎(wan)(wan)成(cheng)(cheng)(cheng)型輥孔(kong)型設(she)計(ji)。冷(leng)彎(wan)(wan)成(cheng)(cheng)(cheng)型輥孔(kong)型設(she)計(ji)的(de)依據是(shi)：冷(leng)彎(wan)(wan)型材(cai)(cai)產品標準、成(cheng)(cheng)(cheng)型材(cai)(cai)料的(de)性能、技術要求、生產機組配置及主要參(can)數。

1. 孔型設計的要求

 ①. 能夠(gou)生(sheng)產出符合技(ji)術(shu)要求的產品斷面形(xing)狀(zhuang)及尺寸精度。

 ②. 產品在全(quan)長上無水平垂直瓢曲及縱向(xiang)扭(niu)轉。

 ③. 彎折(zhe)處減(jian)薄及斷(duan)面殘(can)余應力最小，產品無邊波、皺折(zhe)及裂紋。

 ④. 金屬出人孔(kong)型順利，軋(ya)輥(gun)安裝調(diao)整方便。

 ⑤. 孔(kong)型(xing)(xing)組合配置(zhi)合理、孔(kong)型(xing)(xing)磨損小、輥耗(hao)低、能(neng)耗(hao)小。

 ⑥. 操(cao)作(zuo)方便，可達最大機組生產率。

2. 冷彎成型輥(gun)孔型設計步驟

 ①. 確定(ding)坯料(liao)寬度。

 ②. 確定型鋼對水平輥中(zhong)心線的位置(zhi)。

 ③. 選擇型(xing)鋼成(cheng)型(xing)基(ji)本(ben)中心線（簡稱基(ji)軸）及基(ji)準線段。

 ④. 確定(ding)型鋼過渡斷面數(shu)量(liang)和形狀（俗稱花形圖(tu)）。

 ⑤. 畫(hua)斷面配輥(gun)(gun)圖和(he)單個軋輥(gun)(gun)及輥(gun)(gun)片圖。

 ⑥. 導衛及輔(fu)助工(gong)具設計及圖紙的繪制。

 ⑦. 必要的校(xiao)核。