將板、帶鋼在輥式冷彎成型機上，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)式冷彎(wan)(wan)(wan)(wan)(wan)成(cheng)型(xing)(xing)(xing)(xing)和普通(tong)軋(ya)(ya)制過(guo)程(cheng)一(yi)(yi)樣，冷彎(wan)(wan)(wan)(wan)(wan)成(cheng)型(xing)(xing)(xing)(xing)時帶(dai)坯(pi)(pi)任(ren)意斷面(mian)(mian)上的(de)(de)(de)(de)金屬(shu)流動是穩定(ding)的(de)(de)(de)(de)，不隨時間而(er)變(bian)化(hua)，相鄰兩(liang)(liang)道次(ci)之間帶(dai)坯(pi)(pi)進(jin)入軋(ya)(ya)輥(gun)(gun)位置，如(ru)圖5-10所(suo)示，彎(wan)(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)角(jiao)由(you)(you)上一(yi)(yi)道次(ci)的(de)(de)(de)(de)αn-1增(zeng)大(da)到下(xia)一(yi)(yi)道次(ci)的(de)(de)(de)(de)αn,彎(wan)(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)圓(yuan)弧(hu)半(ban)徑由(you)(you)rn-1,減小為rn.由(you)(you)于板(ban)(ban)坯(pi)(pi)前端(duan)部(bu)(bu)(bu)上拾，彎(wan)(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)角(jiao)增(zeng)大(da)，而(er)產(chan)(chan)生(sheng)(sheng)的(de)(de)(de)(de)張力(li)作(zuo)用(yong)于邊(bian)部(bu)(bu)(bu)，在(zai)(zai)(zai)(zai)相對旋轉的(de)(de)(de)(de)軋(ya)(ya)輥(gun)(gun)的(de)(de)(de)(de)作(zuo)用(yong)下(xia)，板(ban)(ban)帶(dai)坯(pi)(pi)沿軋(ya)(ya)制方(fang)向前進(jin)并實(shi)現(xian)彎(wan)(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)變(bian)形(xing)(xing)(xing)。實(shi)現(xian)板(ban)(ban)坯(pi)(pi)彎(wan)(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)變(bian)形(xing)(xing)(xing)的(de)(de)(de)(de)軋(ya)(ya)輥(gun)(gun)工作(zuo)部(bu)(bu)(bu)分(fen)稱為軋(ya)(ya)槽(cao)（輥(gun)(gun)槽(cao)），由(you)(you)兩(liang)(liang)個和兩(liang)(liang)個以上通(tong)過(guo)軋(ya)(ya)輥(gun)(gun)軸(zhou)(zhou)(zhou)平(ping)(ping)面(mian)(mian)所(suo)構成(cheng)的(de)(de)(de)(de)軋(ya)(ya)槽(cao)斷面(mian)(mian)變(bian)形(xing)(xing)(xing)區稱為孔(kong)(kong)(kong)型(xing)(xing)(xing)(xing)。因此，輥(gun)(gun)式冷彎(wan)(wan)(wan)(wan)(wan)成(cheng)型(xing)(xing)(xing)(xing)亦可(ke)視(shi)為板(ban)(ban)坯(pi)(pi)經(jing)若干孔(kong)(kong)(kong)型(xing)(xing)(xing)(xing)實(shi)現(xian)彎(wan)(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)的(de)(de)(de)(de)穩態變(bian)形(xing)(xing)(xing)過(guo)程(cheng)。從(cong)上一(yi)(yi)道輥(gun)(gun)軸(zhou)(zhou)(zhou)平(ping)(ping)面(mian)(mian)（孔(kong)(kong)(kong)型(xing)(xing)(xing)(xing)）到下(xia)一(yi)(yi)道輥(gun)(gun)軸(zhou)(zhou)(zhou)平(ping)(ping)面(mian)(mian)（孔(kong)(kong)(kong)型(xing)(xing)(xing)(xing)）間距離L稱為平(ping)(ping)緩(huan)(huan)過(guo)渡區長度。L的(de)(de)(de)(de)大(da)小與(yu)機(ji)架間距有關，L愈大(da)變(bian)形(xing)(xing)(xing)愈緩(huan)(huan)和。而(er)平(ping)(ping)緩(huan)(huan)過(guo)渡區又可(ke)細(xi)分(fen)為L1和L2兩(liang)(liang)個區（見圖5-11).板(ban)(ban)坯(pi)(pi)從(cong)前道孔(kong)(kong)(kong)型(xing)(xing)(xing)(xing)（對應彎(wan)(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)角(jiao)an-1)進(jin)入下(xia)道孔(kong)(kong)(kong)型(xing)(xing)(xing)(xing)（對應彎(wan)(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)角(jiao)αn),開始(shi)時坯(pi)(pi)料(liao)前端(duan)部(bu)(bu)(bu)分(fen)與(yu)軋(ya)(ya)輥(gun)(gun)下(xia)軋(ya)(ya)槽(cao)接(jie)觸，在(zai)(zai)(zai)(zai)坯(pi)(pi)料(liao)中形(xing)(xing)(xing)成(cheng)數(shu)值(zhi)不大(da)的(de)(de)(de)(de)彈性應力(li)。軋(ya)(ya)件(jian)(jian)前行與(yu)上軋(ya)(ya)槽(cao)接(jie)觸，在(zai)(zai)(zai)(zai)上下(xia)軋(ya)(ya)槽(cao)作(zuo)用(yong)下(xia)產(chan)(chan)生(sheng)(sheng)塑性彎(wan)(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)，即板(ban)(ban)坯(pi)(pi)在(zai)(zai)(zai)(zai)輥(gun)(gun)軸(zhou)(zhou)(zhou)平(ping)(ping)面(mian)(mian)前（未(wei)通(tong)過(guo)an孔(kong)(kong)(kong)型(xing)(xing)(xing)(xing)）已(yi)開始(shi)了塑性彎(wan)(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)變(bian)形(xing)(xing)(xing)，原(yuan)來(lai)平(ping)(ping)直(zhi)的(de)(de)(de)(de)邊(bian)部(bu)(bu)(bu)產(chan)(chan)生(sheng)(sheng)縱向扭(niu)曲(qu)(qu)(qu)(qu)(qu)，形(xing)(xing)(xing)成(cheng)復雜(za)的(de)(de)(de)(de)曲(qu)(qu)(qu)(qu)(qu)線(xian)表面(mian)(mian)。坯(pi)(pi)料(liao)的(de)(de)(de)(de)橫截(jie)面(mian)(mian)形(xing)(xing)(xing)狀逐漸(jian)按孔(kong)(kong)(kong)型(xing)(xing)(xing)(xing)輪廓形(xing)(xing)(xing)狀變(bian)化(hua)。彎(wan)(wan)(wan)(wan)(wan)折處(chu)金屬(shu)連續經(jing)受彈性到彈塑性變(bian)形(xing)(xing)(xing)。隨彎(wan)(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)角(jiao)增(zeng)大(da)，彎(wan)(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)圓(yuan)弧(hu)半(ban)徑減小，彎(wan)(wan)(wan)(wan)(wan)折處(chu)切(qie)向正應力(li)和彎(wan)(wan)(wan)(wan)(wan)矩增(zeng)加，在(zai)(zai)(zai)(zai)板(ban)(ban)坯(pi)(pi)料(liao)前端(duan)已(yi)變(bian)形(xing)(xing)(xing)部(bu)(bu)(bu)分(fen)與(yu)軋(ya)(ya)輥(gun)(gun)壓緊(jin)軋(ya)(ya)件(jian)(jian)的(de)(de)(de)(de)共(gong)同(tong)作(zuo)用(yong)下(xia)，板(ban)(ban)坯(pi)(pi)邊(bian)部(bu)(bu)(bu)出現(xian)拉(la)應力(li)，引(yin)起(qi)邊(bian)部(bu)(bu)(bu)拉(la)伸，板(ban)(ban)坯(pi)(pi)通(tong)過(guo)軋(ya)(ya)輥(gun)(gun)軸(zhou)(zhou)(zhou)平(ping)(ping)面(mian)(mian)之后（通(tong)過(guo)孔(kong)(kong)(kong)型(xing)(xing)(xing)(xing)后），原(yuan)來(lai)產(chan)(chan)生(sheng)(sheng)縱向扭(niu)曲(qu)(qu)(qu)(qu)(qu)的(de)(de)(de)(de)邊(bian)部(bu)(bu)(bu)被拉(la)平(ping)(ping)，輥(gun)(gun)軸(zhou)(zhou)(zhou)平(ping)(ping)面(mian)(mian)前變(bian)形(xing)(xing)(xing)區長度不再增(zeng)加而(er)保持長度不變(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.

坯料橫(heng)截面各個直線(xian)部分受(shou)縱向拉伸(shen)或(huo)壓縮變形(xing)，與之相(xiang)鄰的曲(qu)(qu)(qu)線(xian)部分受(shou)彎曲(qu)(qu)(qu)變形(xing)，弄清(qing)板(ban)坯在相(xiang)鄰兩(liang)道(dao)次間彎曲(qu)(qu)(qu)變形(xing)行為(wei)，對于制(zhi)定成型(xing)(xing)方案和設計(ji)孔型(xing)(xing)具有(you)一定的意(yi)義(yi)。

為將板(ban)帶材(cai)經連續輥彎(wan)(wan)變形(xing)加工成(cheng)(cheng)合格冷(leng)(leng)彎(wan)(wan)型鋼而進行的(de)成(cheng)(cheng)型方法及(ji)工具(ju)的(de)設(she)計(ji)稱為冷(leng)(leng)彎(wan)(wan)成(cheng)(cheng)型輥孔(kong)型設(she)計(ji)。冷(leng)(leng)彎(wan)(wan)成(cheng)(cheng)型輥孔(kong)型設(she)計(ji)的(de)依據是：冷(leng)(leng)彎(wan)(wan)型材(cai)產品標(biao)準、成(cheng)(cheng)型材(cai)料(liao)的(de)性能(neng)、技術(shu)要求、生產機(ji)組配置及(ji)主(zhu)要參數。

1. 孔型設計(ji)的要(yao)求

 ①. 能(neng)夠生產(chan)出符(fu)合技術要求的產(chan)品斷面形(xing)狀及(ji)尺寸精度。

 ②. 產品在全(quan)長上無(wu)水(shui)平(ping)垂直(zhi)瓢(piao)曲及(ji)縱向扭轉。

 ③. 彎折處減薄及斷面殘余應力最小，產品無邊波、皺折及裂紋(wen)。

 ④. 金屬出人孔型順利，軋(ya)輥安(an)裝調整方(fang)便。

 ⑤. 孔型組合(he)配置合(he)理、孔型磨損(sun)小、輥(gun)耗(hao)低(di)、能耗(hao)小。

 ⑥. 操(cao)作方便，可(ke)達最大機組生產率。

2. 冷(leng)彎成(cheng)型輥孔型設計步(bu)驟

 ①. 確(que)定坯料寬度。

 ②. 確定(ding)型鋼(gang)對水平輥中(zhong)心(xin)線(xian)的位(wei)置(zhi)。

 ③. 選擇型(xing)鋼成型(xing)基(ji)本中心線(xian)（簡稱基(ji)軸）及基(ji)準線(xian)段。

 ④. 確定型鋼過渡斷面(mian)數量(liang)和形狀（俗(su)稱花形圖(tu)）。

 ⑤. 畫斷面配輥(gun)(gun)圖(tu)和單個軋(ya)輥(gun)(gun)及輥(gun)(gun)片(pian)圖(tu)。

 ⑥. 導(dao)衛及輔助工具設計及圖紙的繪制。

 ⑦. 必要(yao)的校(xiao)核。