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)(gun)(gun)式冷彎(wan)(wan)(wan)成(cheng)型(xing)(xing)(xing)和(he)普通(tong)軋(ya)(ya)(ya)制過(guo)(guo)(guo)(guo)(guo)程一樣，冷彎(wan)(wan)(wan)成(cheng)型(xing)(xing)(xing)時帶(dai)坯(pi)(pi)(pi)(pi)(pi)(pi)任意斷(duan)面(mian)上(shang)的(de)(de)金(jin)屬(shu)流動(dong)是(shi)穩定(ding)的(de)(de)，不(bu)(bu)(bu)隨時間(jian)而(er)(er)變(bian)(bian)(bian)(bian)(bian)化(hua)，相鄰兩(liang)(liang)道(dao)(dao)(dao)次之間(jian)帶(dai)坯(pi)(pi)(pi)(pi)(pi)(pi)進(jin)(jin)入(ru)軋(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)位置，如圖(tu)5-10所示，彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)角(jiao)由(you)上(shang)一道(dao)(dao)(dao)次的(de)(de)αn-1增大(da)(da)(da)到下一道(dao)(dao)(dao)次的(de)(de)αn,彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)圓弧半(ban)徑由(you)rn-1,減小為(wei)rn.由(you)于(yu)板(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)前端(duan)部(bu)(bu)上(shang)拾，彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)角(jiao)增大(da)(da)(da)，而(er)(er)產生的(de)(de)張(zhang)力(li)作(zuo)(zuo)用于(yu)邊部(bu)(bu)，在(zai)(zai)相對旋(xuan)轉的(de)(de)軋(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)的(de)(de)作(zuo)(zuo)用下，板(ban)帶(dai)坯(pi)(pi)(pi)(pi)(pi)(pi)沿軋(ya)(ya)(ya)制方向(xiang)前進(jin)(jin)并實現(xian)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)。實現(xian)板(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)的(de)(de)軋(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)工作(zuo)(zuo)部(bu)(bu)分稱(cheng)為(wei)軋(ya)(ya)(ya)槽(cao)（輥(gun)(gun)(gun)(gun)槽(cao)），由(you)兩(liang)(liang)個(ge)和(he)兩(liang)(liang)個(ge)以上(shang)通(tong)過(guo)(guo)(guo)(guo)(guo)軋(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)面(mian)所構成(cheng)的(de)(de)軋(ya)(ya)(ya)槽(cao)斷(duan)面(mian)變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)區(qu)稱(cheng)為(wei)孔(kong)型(xing)(xing)(xing)。因此，輥(gun)(gun)(gun)(gun)式冷彎(wan)(wan)(wan)成(cheng)型(xing)(xing)(xing)亦可視為(wei)板(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)經若干孔(kong)型(xing)(xing)(xing)實現(xian)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)的(de)(de)穩態變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)過(guo)(guo)(guo)(guo)(guo)程。從(cong)上(shang)一道(dao)(dao)(dao)輥(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)面(mian)（孔(kong)型(xing)(xing)(xing)）到下一道(dao)(dao)(dao)輥(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)面(mian)（孔(kong)型(xing)(xing)(xing)）間(jian)距離L稱(cheng)為(wei)平(ping)(ping)緩過(guo)(guo)(guo)(guo)(guo)渡區(qu)長度。L的(de)(de)大(da)(da)(da)小與(yu)(yu)機架間(jian)距有關，L愈(yu)大(da)(da)(da)變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)愈(yu)緩和(he)。而(er)(er)平(ping)(ping)緩過(guo)(guo)(guo)(guo)(guo)渡區(qu)又可細分為(wei)L1和(he)L2兩(liang)(liang)個(ge)區(qu)（見圖(tu)5-11).板(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)從(cong)前道(dao)(dao)(dao)孔(kong)型(xing)(xing)(xing)（對應(ying)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)角(jiao)an-1)進(jin)(jin)入(ru)下道(dao)(dao)(dao)孔(kong)型(xing)(xing)(xing)（對應(ying)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)角(jiao)αn),開始時坯(pi)(pi)(pi)(pi)(pi)(pi)料前端(duan)部(bu)(bu)分與(yu)(yu)軋(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)下軋(ya)(ya)(ya)槽(cao)接觸(chu)，在(zai)(zai)坯(pi)(pi)(pi)(pi)(pi)(pi)料中形(xing)(xing)成(cheng)數值不(bu)(bu)(bu)大(da)(da)(da)的(de)(de)彈性(xing)應(ying)力(li)。軋(ya)(ya)(ya)件前行與(yu)(yu)上(shang)軋(ya)(ya)(ya)槽(cao)接觸(chu)，在(zai)(zai)上(shang)下軋(ya)(ya)(ya)槽(cao)作(zuo)(zuo)用下產生塑(su)性(xing)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)，即板(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)在(zai)(zai)輥(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)面(mian)前（未通(tong)過(guo)(guo)(guo)(guo)(guo)an孔(kong)型(xing)(xing)(xing)）已開始了塑(su)性(xing)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)，原(yuan)(yuan)來(lai)平(ping)(ping)直的(de)(de)邊部(bu)(bu)產生縱向(xiang)扭(niu)曲(qu)(qu)(qu)(qu)(qu)(qu)，形(xing)(xing)成(cheng)復(fu)雜的(de)(de)曲(qu)(qu)(qu)(qu)(qu)(qu)線(xian)表面(mian)。坯(pi)(pi)(pi)(pi)(pi)(pi)料的(de)(de)橫(heng)截面(mian)形(xing)(xing)狀(zhuang)逐漸(jian)按孔(kong)型(xing)(xing)(xing)輪廓形(xing)(xing)狀(zhuang)變(bian)(bian)(bian)(bian)(bian)化(hua)。彎(wan)(wan)(wan)折處金(jin)屬(shu)連(lian)續經受彈性(xing)到彈塑(su)性(xing)變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)。隨彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)角(jiao)增大(da)(da)(da)，彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)(qu)圓弧半(ban)徑減小，彎(wan)(wan)(wan)折處切向(xiang)正應(ying)力(li)和(he)彎(wan)(wan)(wan)矩(ju)增加，在(zai)(zai)板(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)料前端(duan)已變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)部(bu)(bu)分與(yu)(yu)軋(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)壓(ya)緊軋(ya)(ya)(ya)件的(de)(de)共同作(zuo)(zuo)用下，板(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)邊部(bu)(bu)出現(xian)拉(la)(la)應(ying)力(li)，引起(qi)邊部(bu)(bu)拉(la)(la)伸，板(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)通(tong)過(guo)(guo)(guo)(guo)(guo)軋(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)面(mian)之后(hou)（通(tong)過(guo)(guo)(guo)(guo)(guo)孔(kong)型(xing)(xing)(xing)后(hou)），原(yuan)(yuan)來(lai)產生縱向(xiang)扭(niu)曲(qu)(qu)(qu)(qu)(qu)(qu)的(de)(de)邊部(bu)(bu)被拉(la)(la)平(ping)(ping)，輥(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)面(mian)前變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)區(qu)長度不(bu)(bu)(bu)再增加而(er)(er)保持長度不(bu)(bu)(bu)變(bian)(bian)(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.

坯料橫截面各(ge)個直線部分受縱向拉伸(shen)或壓(ya)縮變形，與之(zhi)相(xiang)鄰的曲(qu)(qu)線部分受彎曲(qu)(qu)變形，弄清板(ban)坯在相(xiang)鄰兩道(dao)次間彎曲(qu)(qu)變形行為，對于制(zhi)定成型方案和設計(ji)孔型具有一定的意義。

為將(jiang)板(ban)帶材(cai)經連續輥彎(wan)變形加(jia)工(gong)成(cheng)合格冷彎(wan)型(xing)鋼而進行的(de)(de)(de)成(cheng)型(xing)方(fang)法及工(gong)具的(de)(de)(de)設計(ji)稱為冷彎(wan)成(cheng)型(xing)輥孔型(xing)設計(ji)。冷彎(wan)成(cheng)型(xing)輥孔型(xing)設計(ji)的(de)(de)(de)依據是：冷彎(wan)型(xing)材(cai)產品標準、成(cheng)型(xing)材(cai)料(liao)的(de)(de)(de)性(xing)能、技術(shu)要(yao)求、生產機組配(pei)置(zhi)及主要(yao)參數。

1. 孔(kong)型設(she)計的(de)要(yao)求

 ①. 能(neng)夠(gou)生產(chan)出符合(he)技術要求的(de)產(chan)品(pin)斷(duan)面形(xing)狀及尺寸(cun)精(jing)度(du)。

 ②. 產品在全長上無水(shui)平(ping)垂直瓢曲及縱向扭轉。

 ③. 彎(wan)折處(chu)減薄及斷(duan)面殘余(yu)應力最(zui)小，產品(pin)無(wu)邊波、皺折及裂紋(wen)。

 ④. 金屬出(chu)人(ren)孔型順利，軋輥安(an)裝調(diao)整方便。

 ⑤. 孔型組(zu)合配置合理、孔型磨(mo)損(sun)小、輥耗低、能耗小。

 ⑥. 操(cao)作方便(bian)，可達最(zui)大機組生產率。

2. 冷彎成型輥孔型設計步(bu)驟

 ①. 確定坯料寬(kuan)度。

 ②. 確定型(xing)鋼對水平輥中心線的位置。

 ③. 選擇型鋼(gang)成型基(ji)本中(zhong)心線（簡稱基(ji)軸）及基(ji)準線段(duan)。

 ④. 確定型鋼過渡斷面(mian)數量和形(xing)狀（俗稱花(hua)形(xing)圖）。

 ⑤. 畫(hua)斷面(mian)配輥圖和單個軋輥及(ji)輥片(pian)圖。

 ⑥. 導衛(wei)及輔助工具設計及圖(tu)紙的繪制。

 ⑦. 必要的(de)校核。