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。

 輥式冷(leng)彎(wan)(wan)(wan)成型(xing)(xing)(xing)(xing)(xing)和(he)(he)普(pu)通(tong)軋(ya)(ya)制過(guo)(guo)程一樣，冷(leng)彎(wan)(wan)(wan)成型(xing)(xing)(xing)(xing)(xing)時(shi)帶(dai)(dai)坯(pi)(pi)(pi)任意斷面(mian)上(shang)(shang)的(de)(de)金屬流(liu)動是穩定的(de)(de)，不(bu)隨時(shi)間而變(bian)(bian)(bian)(bian)化，相(xiang)鄰(lin)兩(liang)道(dao)次(ci)之(zhi)間帶(dai)(dai)坯(pi)(pi)(pi)進(jin)入軋(ya)(ya)輥位(wei)置，如(ru)圖5-10所示(shi)，彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)角(jiao)由(you)(you)上(shang)(shang)一道(dao)次(ci)的(de)(de)αn-1增(zeng)大(da)到下(xia)(xia)一道(dao)次(ci)的(de)(de)αn,彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)圓弧半徑由(you)(you)rn-1,減小為(wei)(wei)rn.由(you)(you)于板(ban)(ban)坯(pi)(pi)(pi)前(qian)(qian)(qian)端(duan)部(bu)(bu)(bu)上(shang)(shang)拾，彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)角(jiao)增(zeng)大(da)，而產生(sheng)的(de)(de)張力作(zuo)(zuo)用于邊部(bu)(bu)(bu)，在相(xiang)對旋轉的(de)(de)軋(ya)(ya)輥的(de)(de)作(zuo)(zuo)用下(xia)(xia)，板(ban)(ban)帶(dai)(dai)坯(pi)(pi)(pi)沿(yan)軋(ya)(ya)制方向(xiang)前(qian)(qian)(qian)進(jin)并實(shi)(shi)現(xian)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)。實(shi)(shi)現(xian)板(ban)(ban)坯(pi)(pi)(pi)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)的(de)(de)軋(ya)(ya)輥工作(zuo)(zuo)部(bu)(bu)(bu)分(fen)(fen)稱(cheng)(cheng)為(wei)(wei)軋(ya)(ya)槽(cao)(cao)(cao)（輥槽(cao)(cao)(cao)），由(you)(you)兩(liang)個和(he)(he)兩(liang)個以上(shang)(shang)通(tong)過(guo)(guo)軋(ya)(ya)輥軸(zhou)平(ping)面(mian)所構(gou)成的(de)(de)軋(ya)(ya)槽(cao)(cao)(cao)斷面(mian)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)區(qu)(qu)(qu)稱(cheng)(cheng)為(wei)(wei)孔(kong)(kong)型(xing)(xing)(xing)(xing)(xing)。因此，輥式冷(leng)彎(wan)(wan)(wan)成型(xing)(xing)(xing)(xing)(xing)亦可(ke)視(shi)為(wei)(wei)板(ban)(ban)坯(pi)(pi)(pi)經(jing)若(ruo)干孔(kong)(kong)型(xing)(xing)(xing)(xing)(xing)實(shi)(shi)現(xian)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)的(de)(de)穩態變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)過(guo)(guo)程。從上(shang)(shang)一道(dao)輥軸(zhou)平(ping)面(mian)（孔(kong)(kong)型(xing)(xing)(xing)(xing)(xing)）到下(xia)(xia)一道(dao)輥軸(zhou)平(ping)面(mian)（孔(kong)(kong)型(xing)(xing)(xing)(xing)(xing)）間距(ju)離L稱(cheng)(cheng)為(wei)(wei)平(ping)緩(huan)過(guo)(guo)渡區(qu)(qu)(qu)長(chang)度。L的(de)(de)大(da)小與(yu)(yu)機架間距(ju)有關(guan)，L愈(yu)大(da)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)愈(yu)緩(huan)和(he)(he)。而平(ping)緩(huan)過(guo)(guo)渡區(qu)(qu)(qu)又(you)可(ke)細分(fen)(fen)為(wei)(wei)L1和(he)(he)L2兩(liang)個區(qu)(qu)(qu)（見圖5-11).板(ban)(ban)坯(pi)(pi)(pi)從前(qian)(qian)(qian)道(dao)孔(kong)(kong)型(xing)(xing)(xing)(xing)(xing)（對應(ying)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)角(jiao)an-1)進(jin)入下(xia)(xia)道(dao)孔(kong)(kong)型(xing)(xing)(xing)(xing)(xing)（對應(ying)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)角(jiao)αn),開始時(shi)坯(pi)(pi)(pi)料(liao)(liao)前(qian)(qian)(qian)端(duan)部(bu)(bu)(bu)分(fen)(fen)與(yu)(yu)軋(ya)(ya)輥下(xia)(xia)軋(ya)(ya)槽(cao)(cao)(cao)接觸(chu)，在坯(pi)(pi)(pi)料(liao)(liao)中形(xing)(xing)(xing)成數(shu)值不(bu)大(da)的(de)(de)彈(dan)性(xing)(xing)(xing)應(ying)力。軋(ya)(ya)件(jian)前(qian)(qian)(qian)行與(yu)(yu)上(shang)(shang)軋(ya)(ya)槽(cao)(cao)(cao)接觸(chu)，在上(shang)(shang)下(xia)(xia)軋(ya)(ya)槽(cao)(cao)(cao)作(zuo)(zuo)用下(xia)(xia)產生(sheng)塑性(xing)(xing)(xing)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)，即板(ban)(ban)坯(pi)(pi)(pi)在輥軸(zhou)平(ping)面(mian)前(qian)(qian)(qian)（未通(tong)過(guo)(guo)an孔(kong)(kong)型(xing)(xing)(xing)(xing)(xing)）已(yi)開始了塑性(xing)(xing)(xing)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)，原來平(ping)直(zhi)的(de)(de)邊部(bu)(bu)(bu)產生(sheng)縱向(xiang)扭(niu)曲(qu)(qu)(qu)(qu)，形(xing)(xing)(xing)成復雜的(de)(de)曲(qu)(qu)(qu)(qu)線(xian)表面(mian)。坯(pi)(pi)(pi)料(liao)(liao)的(de)(de)橫截面(mian)形(xing)(xing)(xing)狀逐(zhu)漸(jian)按孔(kong)(kong)型(xing)(xing)(xing)(xing)(xing)輪(lun)廓形(xing)(xing)(xing)狀變(bian)(bian)(bian)(bian)化。彎(wan)(wan)(wan)折(zhe)處金屬連續經(jing)受彈(dan)性(xing)(xing)(xing)到彈(dan)塑性(xing)(xing)(xing)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)。隨彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)角(jiao)增(zeng)大(da)，彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)圓弧半徑減小，彎(wan)(wan)(wan)折(zhe)處切(qie)向(xiang)正應(ying)力和(he)(he)彎(wan)(wan)(wan)矩(ju)增(zeng)加，在板(ban)(ban)坯(pi)(pi)(pi)料(liao)(liao)前(qian)(qian)(qian)端(duan)已(yi)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)部(bu)(bu)(bu)分(fen)(fen)與(yu)(yu)軋(ya)(ya)輥壓(ya)緊軋(ya)(ya)件(jian)的(de)(de)共同作(zuo)(zuo)用下(xia)(xia)，板(ban)(ban)坯(pi)(pi)(pi)邊部(bu)(bu)(bu)出現(xian)拉應(ying)力，引起邊部(bu)(bu)(bu)拉伸，板(ban)(ban)坯(pi)(pi)(pi)通(tong)過(guo)(guo)軋(ya)(ya)輥軸(zhou)平(ping)面(mian)之(zhi)后（通(tong)過(guo)(guo)孔(kong)(kong)型(xing)(xing)(xing)(xing)(xing)后），原來產生(sheng)縱向(xiang)扭(niu)曲(qu)(qu)(qu)(qu)的(de)(de)邊部(bu)(bu)(bu)被拉平(ping)，輥軸(zhou)平(ping)面(mian)前(qian)(qian)(qian)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)區(qu)(qu)(qu)長(chang)度不(bu)再增(zeng)加而保持(chi)長(chang)度不(bu)變(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(pi)(pi)料橫截面各(ge)個直(zhi)線部分(fen)受縱向拉(la)伸(shen)或(huo)壓縮變形(xing)，與之相鄰(lin)(lin)的曲線部分(fen)受彎(wan)曲變形(xing)，弄清板坯(pi)(pi)在相鄰(lin)(lin)兩道次間彎(wan)曲變形(xing)行(xing)為，對于(yu)制定成型方(fang)案和設(she)計孔型具有一定的意義。

為將板帶材經(jing)連續輥彎(wan)變(bian)形加(jia)工成(cheng)合格冷(leng)彎(wan)型(xing)(xing)鋼而進行的成(cheng)型(xing)(xing)方法(fa)及工具的設(she)計稱為冷(leng)彎(wan)成(cheng)型(xing)(xing)輥孔(kong)型(xing)(xing)設(she)計。冷(leng)彎(wan)成(cheng)型(xing)(xing)輥孔(kong)型(xing)(xing)設(she)計的依據(ju)是：冷(leng)彎(wan)型(xing)(xing)材產品標準、成(cheng)型(xing)(xing)材料的性(xing)能(neng)、技術要(yao)求(qiu)、生產機組配置及主要(yao)參數(shu)。

1. 孔型設計的要求(qiu)

 ①. 能夠生產出(chu)符合技術要求的(de)產品斷面形狀(zhuang)及尺寸精度。

 ②. 產品在全長上無水平垂直瓢曲及(ji)縱向(xiang)扭轉。

 ③. 彎折(zhe)處減薄及斷面殘余(yu)應力最小，產(chan)品無邊波、皺折(zhe)及裂紋。

 ④. 金(jin)屬出人孔型順利，軋輥(gun)安裝調整方便。

 ⑤. 孔型組合(he)配(pei)置(zhi)合(he)理、孔型磨損小(xiao)、輥耗(hao)低(di)、能耗(hao)小(xiao)。

 ⑥. 操作方便(bian)，可達最大機組(zu)生產率(lv)。

2. 冷彎成(cheng)型輥孔(kong)型設(she)計步驟

 ①. 確定坯料寬度(du)。

 ②. 確(que)定型鋼(gang)對水平輥中心線的位置。

 ③. 選擇型鋼成型基本中心線(xian)（簡稱(cheng)基軸）及基準線(xian)段(duan)。

 ④. 確定型鋼過渡斷面數(shu)量和形(xing)狀（俗(su)稱花形(xing)圖）。

 ⑤. 畫斷面配輥圖(tu)和(he)單個軋輥及輥片圖(tu)。

 ⑥. 導衛及輔助工具設計及圖紙(zhi)的繪制。

 ⑦. 必(bi)要的校核(he)。