將板、帶鋼在輥式冷彎成型(xing)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(leng)彎(wan)(wan)(wan)(wan)成型(xing)(xing)(xing)(xing)和(he)(he)普通(tong)軋(ya)(ya)(ya)制過(guo)程一(yi)(yi)樣，冷(leng)彎(wan)(wan)(wan)(wan)成型(xing)(xing)(xing)(xing)時帶(dai)坯(pi)(pi)任(ren)意斷面上(shang)(shang)的(de)(de)(de)(de)金(jin)屬流(liu)動是(shi)穩(wen)定的(de)(de)(de)(de)，不(bu)隨(sui)時間(jian)(jian)而變(bian)(bian)(bian)化(hua)(hua)，相鄰兩(liang)道(dao)次(ci)之(zhi)間(jian)(jian)帶(dai)坯(pi)(pi)進入(ru)軋(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)位置，如(ru)圖5-10所示，彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)角(jiao)由(you)(you)上(shang)(shang)一(yi)(yi)道(dao)次(ci)的(de)(de)(de)(de)αn-1增(zeng)(zeng)(zeng)大到(dao)下(xia)(xia)一(yi)(yi)道(dao)次(ci)的(de)(de)(de)(de)αn,彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)圓(yuan)(yuan)弧半徑(jing)由(you)(you)rn-1,減(jian)(jian)小(xiao)為(wei)(wei)rn.由(you)(you)于板(ban)(ban)坯(pi)(pi)前(qian)(qian)端(duan)部(bu)(bu)上(shang)(shang)拾，彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)角(jiao)增(zeng)(zeng)(zeng)大，而產(chan)生(sheng)的(de)(de)(de)(de)張力(li)作用于邊部(bu)(bu)，在相對旋(xuan)轉的(de)(de)(de)(de)軋(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)的(de)(de)(de)(de)作用下(xia)(xia)，板(ban)(ban)帶(dai)坯(pi)(pi)沿軋(ya)(ya)(ya)制方向(xiang)(xiang)前(qian)(qian)進并實(shi)(shi)現彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)變(bian)(bian)(bian)形(xing)(xing)(xing)。實(shi)(shi)現板(ban)(ban)坯(pi)(pi)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)變(bian)(bian)(bian)形(xing)(xing)(xing)的(de)(de)(de)(de)軋(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)工作部(bu)(bu)分(fen)(fen)稱為(wei)(wei)軋(ya)(ya)(ya)槽(cao)(cao)（輥(gun)(gun)(gun)(gun)槽(cao)(cao)），由(you)(you)兩(liang)個(ge)和(he)(he)兩(liang)個(ge)以(yi)上(shang)(shang)通(tong)過(guo)軋(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)面所構成的(de)(de)(de)(de)軋(ya)(ya)(ya)槽(cao)(cao)斷面變(bian)(bian)(bian)形(xing)(xing)(xing)區稱為(wei)(wei)孔(kong)型(xing)(xing)(xing)(xing)。因此，輥(gun)(gun)(gun)(gun)式冷(leng)彎(wan)(wan)(wan)(wan)成型(xing)(xing)(xing)(xing)亦可(ke)視為(wei)(wei)板(ban)(ban)坯(pi)(pi)經若干孔(kong)型(xing)(xing)(xing)(xing)實(shi)(shi)現彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)的(de)(de)(de)(de)穩(wen)態(tai)變(bian)(bian)(bian)形(xing)(xing)(xing)過(guo)程。從上(shang)(shang)一(yi)(yi)道(dao)輥(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)面（孔(kong)型(xing)(xing)(xing)(xing)）到(dao)下(xia)(xia)一(yi)(yi)道(dao)輥(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)面（孔(kong)型(xing)(xing)(xing)(xing)）間(jian)(jian)距(ju)離L稱為(wei)(wei)平(ping)(ping)(ping)緩(huan)過(guo)渡區長(chang)(chang)度(du)。L的(de)(de)(de)(de)大小(xiao)與機架間(jian)(jian)距(ju)有關，L愈大變(bian)(bian)(bian)形(xing)(xing)(xing)愈緩(huan)和(he)(he)。而平(ping)(ping)(ping)緩(huan)過(guo)渡區又可(ke)細分(fen)(fen)為(wei)(wei)L1和(he)(he)L2兩(liang)個(ge)區（見圖5-11).板(ban)(ban)坯(pi)(pi)從前(qian)(qian)道(dao)孔(kong)型(xing)(xing)(xing)(xing)（對應(ying)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)角(jiao)an-1)進入(ru)下(xia)(xia)道(dao)孔(kong)型(xing)(xing)(xing)(xing)（對應(ying)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)角(jiao)αn),開始時坯(pi)(pi)料(liao)前(qian)(qian)端(duan)部(bu)(bu)分(fen)(fen)與軋(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)下(xia)(xia)軋(ya)(ya)(ya)槽(cao)(cao)接觸，在坯(pi)(pi)料(liao)中形(xing)(xing)(xing)成數值不(bu)大的(de)(de)(de)(de)彈性(xing)(xing)應(ying)力(li)。軋(ya)(ya)(ya)件前(qian)(qian)行與上(shang)(shang)軋(ya)(ya)(ya)槽(cao)(cao)接觸，在上(shang)(shang)下(xia)(xia)軋(ya)(ya)(ya)槽(cao)(cao)作用下(xia)(xia)產(chan)生(sheng)塑性(xing)(xing)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)，即板(ban)(ban)坯(pi)(pi)在輥(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)面前(qian)(qian)（未通(tong)過(guo)an孔(kong)型(xing)(xing)(xing)(xing)）已開始了塑性(xing)(xing)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)變(bian)(bian)(bian)形(xing)(xing)(xing)，原(yuan)(yuan)來(lai)平(ping)(ping)(ping)直的(de)(de)(de)(de)邊部(bu)(bu)產(chan)生(sheng)縱向(xiang)(xiang)扭(niu)曲(qu)(qu)(qu)，形(xing)(xing)(xing)成復雜的(de)(de)(de)(de)曲(qu)(qu)(qu)線表(biao)面。坯(pi)(pi)料(liao)的(de)(de)(de)(de)橫截面形(xing)(xing)(xing)狀逐漸(jian)按孔(kong)型(xing)(xing)(xing)(xing)輪廓形(xing)(xing)(xing)狀變(bian)(bian)(bian)化(hua)(hua)。彎(wan)(wan)(wan)(wan)折處(chu)金(jin)屬連續經受彈性(xing)(xing)到(dao)彈塑性(xing)(xing)變(bian)(bian)(bian)形(xing)(xing)(xing)。隨(sui)彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)角(jiao)增(zeng)(zeng)(zeng)大，彎(wan)(wan)(wan)(wan)曲(qu)(qu)(qu)圓(yuan)(yuan)弧半徑(jing)減(jian)(jian)小(xiao)，彎(wan)(wan)(wan)(wan)折處(chu)切向(xiang)(xiang)正應(ying)力(li)和(he)(he)彎(wan)(wan)(wan)(wan)矩增(zeng)(zeng)(zeng)加(jia)，在板(ban)(ban)坯(pi)(pi)料(liao)前(qian)(qian)端(duan)已變(bian)(bian)(bian)形(xing)(xing)(xing)部(bu)(bu)分(fen)(fen)與軋(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)壓(ya)緊軋(ya)(ya)(ya)件的(de)(de)(de)(de)共同(tong)作用下(xia)(xia)，板(ban)(ban)坯(pi)(pi)邊部(bu)(bu)出現拉應(ying)力(li)，引(yin)起邊部(bu)(bu)拉伸，板(ban)(ban)坯(pi)(pi)通(tong)過(guo)軋(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)面之(zhi)后(hou)（通(tong)過(guo)孔(kong)型(xing)(xing)(xing)(xing)后(hou)），原(yuan)(yuan)來(lai)產(chan)生(sheng)縱向(xiang)(xiang)扭(niu)曲(qu)(qu)(qu)的(de)(de)(de)(de)邊部(bu)(bu)被拉平(ping)(ping)(ping)，輥(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)面前(qian)(qian)變(bian)(bian)(bian)形(xing)(xing)(xing)區長(chang)(chang)度(du)不(bu)再增(zeng)(zeng)(zeng)加(jia)而保(bao)持長(chang)(chang)度(du)不(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(pi)料(liao)橫(heng)截面(mian)各(ge)個直線部分(fen)受縱向拉(la)伸或壓縮變形(xing)，與之相鄰的曲(qu)線部分(fen)受彎(wan)曲(qu)變形(xing)，弄清板坯(pi)在相鄰兩道次間彎(wan)曲(qu)變形(xing)行為，對(dui)于制定(ding)成型方案和設計(ji)孔型具有一定(ding)的意義(yi)。

為(wei)將板帶(dai)材經連續輥(gun)彎(wan)變形加工成(cheng)合(he)格冷彎(wan)型(xing)(xing)鋼(gang)而進行(xing)的(de)成(cheng)型(xing)(xing)方法及工具的(de)設計稱為(wei)冷彎(wan)成(cheng)型(xing)(xing)輥(gun)孔型(xing)(xing)設計。冷彎(wan)成(cheng)型(xing)(xing)輥(gun)孔型(xing)(xing)設計的(de)依據是：冷彎(wan)型(xing)(xing)材產(chan)品標準(zhun)、成(cheng)型(xing)(xing)材料的(de)性能、技術(shu)要求、生產(chan)機(ji)組配(pei)置及主要參(can)數。

1. 孔型(xing)設計的(de)要求

 ①. 能夠生產出符(fu)合技術要求的產品斷面形狀及(ji)尺寸精度。

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

 ③. 彎折處減薄及斷面殘余應(ying)力(li)最小，產品無(wu)邊(bian)波、皺折及裂紋(wen)。

 ④. 金(jin)屬出人(ren)孔(kong)型順利(li)，軋(ya)輥安裝(zhuang)調整方(fang)便。

 ⑤. 孔(kong)型組合配置合理、孔(kong)型磨損小、輥(gun)耗(hao)低、能(neng)耗(hao)小。

 ⑥. 操作方便，可(ke)達最大(da)機(ji)組(zu)生產率。

2. 冷彎(wan)成型輥孔(kong)型設計步驟

 ①. 確定(ding)坯料寬度。

 ②. 確定型鋼對水平輥中心線的位置。

 ③. 選擇(ze)型鋼成(cheng)型基(ji)本中心線(xian)(xian)（簡稱基(ji)軸）及(ji)基(ji)準(zhun)線(xian)(xian)段。

 ④. 確定型鋼過渡斷面數量和形(xing)狀(zhuang)（俗稱花形(xing)圖）。

 ⑤. 畫斷面配輥(gun)圖和單個軋輥(gun)及輥(gun)片圖。

 ⑥. 導衛及(ji)輔(fu)助工具設(she)計及(ji)圖(tu)紙(zhi)的(de)繪制(zhi)。

 ⑦. 必要的校核。