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)(gun)式(shi)冷(leng)彎(wan)(wan)(wan)成(cheng)(cheng)型(xing)和普通(tong)軋(ya)(ya)(ya)(ya)制過(guo)程(cheng)一(yi)樣，冷(leng)彎(wan)(wan)(wan)成(cheng)(cheng)型(xing)時(shi)帶坯(pi)(pi)(pi)(pi)(pi)(pi)(pi)任意斷面(mian)上(shang)(shang)的(de)(de)(de)(de)金屬(shu)流動是(shi)穩(wen)定的(de)(de)(de)(de)，不(bu)隨時(shi)間而變(bian)(bian)(bian)(bian)(bian)化，相(xiang)鄰兩道(dao)次之間帶坯(pi)(pi)(pi)(pi)(pi)(pi)(pi)進(jin)入軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)(gun)位置，如圖(tu)5-10所示(shi)，彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)角(jiao)(jiao)(jiao)由上(shang)(shang)一(yi)道(dao)次的(de)(de)(de)(de)αn-1增大(da)(da)(da)到(dao)(dao)下(xia)(xia)(xia)(xia)(xia)一(yi)道(dao)次的(de)(de)(de)(de)αn,彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)圓(yuan)弧半徑(jing)由rn-1,減(jian)小為(wei)rn.由于板(ban)(ban)(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)(pi)前(qian)(qian)(qian)(qian)端(duan)部(bu)上(shang)(shang)拾，彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)角(jiao)(jiao)(jiao)增大(da)(da)(da)，而產生(sheng)(sheng)的(de)(de)(de)(de)張(zhang)力(li)作(zuo)(zuo)用(yong)于邊(bian)部(bu)，在(zai)相(xiang)對旋(xuan)轉(zhuan)的(de)(de)(de)(de)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)(gun)的(de)(de)(de)(de)作(zuo)(zuo)用(yong)下(xia)(xia)(xia)(xia)(xia)，板(ban)(ban)(ban)帶坯(pi)(pi)(pi)(pi)(pi)(pi)(pi)沿軋(ya)(ya)(ya)(ya)制方向(xiang)(xiang)前(qian)(qian)(qian)(qian)進(jin)并實(shi)現(xian)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)變(bian)(bian)(bian)(bian)(bian)形(xing)。實(shi)現(xian)板(ban)(ban)(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)(pi)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)變(bian)(bian)(bian)(bian)(bian)形(xing)的(de)(de)(de)(de)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)(gun)工作(zuo)(zuo)部(bu)分(fen)稱為(wei)軋(ya)(ya)(ya)(ya)槽(cao)(cao)(cao)（輥(gun)(gun)(gun)(gun)(gun)槽(cao)(cao)(cao)），由兩個和兩個以上(shang)(shang)通(tong)過(guo)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)(ping)(ping)面(mian)所構(gou)成(cheng)(cheng)的(de)(de)(de)(de)軋(ya)(ya)(ya)(ya)槽(cao)(cao)(cao)斷面(mian)變(bian)(bian)(bian)(bian)(bian)形(xing)區稱為(wei)孔型(xing)。因此，輥(gun)(gun)(gun)(gun)(gun)式(shi)冷(leng)彎(wan)(wan)(wan)成(cheng)(cheng)型(xing)亦可(ke)視為(wei)板(ban)(ban)(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)(pi)經(jing)若(ruo)干孔型(xing)實(shi)現(xian)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)的(de)(de)(de)(de)穩(wen)態變(bian)(bian)(bian)(bian)(bian)形(xing)過(guo)程(cheng)。從(cong)上(shang)(shang)一(yi)道(dao)輥(gun)(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)(ping)(ping)面(mian)（孔型(xing)）到(dao)(dao)下(xia)(xia)(xia)(xia)(xia)一(yi)道(dao)輥(gun)(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)(ping)(ping)面(mian)（孔型(xing)）間距(ju)離(li)L稱為(wei)平(ping)(ping)(ping)(ping)(ping)緩(huan)過(guo)渡(du)區長(chang)度。L的(de)(de)(de)(de)大(da)(da)(da)小與(yu)機架(jia)間距(ju)有關，L愈(yu)(yu)大(da)(da)(da)變(bian)(bian)(bian)(bian)(bian)形(xing)愈(yu)(yu)緩(huan)和。而平(ping)(ping)(ping)(ping)(ping)緩(huan)過(guo)渡(du)區又可(ke)細(xi)分(fen)為(wei)L1和L2兩個區（見圖(tu)5-11).板(ban)(ban)(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)(pi)從(cong)前(qian)(qian)(qian)(qian)道(dao)孔型(xing)（對應(ying)(ying)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)角(jiao)(jiao)(jiao)an-1)進(jin)入下(xia)(xia)(xia)(xia)(xia)道(dao)孔型(xing)（對應(ying)(ying)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)角(jiao)(jiao)(jiao)αn),開始時(shi)坯(pi)(pi)(pi)(pi)(pi)(pi)(pi)料(liao)(liao)(liao)前(qian)(qian)(qian)(qian)端(duan)部(bu)分(fen)與(yu)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)(gun)下(xia)(xia)(xia)(xia)(xia)軋(ya)(ya)(ya)(ya)槽(cao)(cao)(cao)接觸(chu)，在(zai)坯(pi)(pi)(pi)(pi)(pi)(pi)(pi)料(liao)(liao)(liao)中形(xing)成(cheng)(cheng)數值不(bu)大(da)(da)(da)的(de)(de)(de)(de)彈性(xing)(xing)應(ying)(ying)力(li)。軋(ya)(ya)(ya)(ya)件前(qian)(qian)(qian)(qian)行(xing)與(yu)上(shang)(shang)軋(ya)(ya)(ya)(ya)槽(cao)(cao)(cao)接觸(chu)，在(zai)上(shang)(shang)下(xia)(xia)(xia)(xia)(xia)軋(ya)(ya)(ya)(ya)槽(cao)(cao)(cao)作(zuo)(zuo)用(yong)下(xia)(xia)(xia)(xia)(xia)產生(sheng)(sheng)塑(su)性(xing)(xing)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)，即板(ban)(ban)(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)(pi)在(zai)輥(gun)(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)(ping)(ping)面(mian)前(qian)(qian)(qian)(qian)（未(wei)通(tong)過(guo)an孔型(xing)）已(yi)開始了塑(su)性(xing)(xing)彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)變(bian)(bian)(bian)(bian)(bian)形(xing)，原來平(ping)(ping)(ping)(ping)(ping)直的(de)(de)(de)(de)邊(bian)部(bu)產生(sheng)(sheng)縱向(xiang)(xiang)扭(niu)(niu)曲(qu)(qu)(qu)(qu)(qu)，形(xing)成(cheng)(cheng)復雜(za)的(de)(de)(de)(de)曲(qu)(qu)(qu)(qu)(qu)線表(biao)面(mian)。坯(pi)(pi)(pi)(pi)(pi)(pi)(pi)料(liao)(liao)(liao)的(de)(de)(de)(de)橫截(jie)面(mian)形(xing)狀逐漸(jian)按孔型(xing)輪廓形(xing)狀變(bian)(bian)(bian)(bian)(bian)化。彎(wan)(wan)(wan)折處金屬(shu)連續經(jing)受彈性(xing)(xing)到(dao)(dao)彈塑(su)性(xing)(xing)變(bian)(bian)(bian)(bian)(bian)形(xing)。隨彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)角(jiao)(jiao)(jiao)增大(da)(da)(da)，彎(wan)(wan)(wan)曲(qu)(qu)(qu)(qu)(qu)圓(yuan)弧半徑(jing)減(jian)小，彎(wan)(wan)(wan)折處切向(xiang)(xiang)正(zheng)應(ying)(ying)力(li)和彎(wan)(wan)(wan)矩增加(jia)，在(zai)板(ban)(ban)(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)(pi)料(liao)(liao)(liao)前(qian)(qian)(qian)(qian)端(duan)已(yi)變(bian)(bian)(bian)(bian)(bian)形(xing)部(bu)分(fen)與(yu)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)(gun)壓緊軋(ya)(ya)(ya)(ya)件的(de)(de)(de)(de)共同作(zuo)(zuo)用(yong)下(xia)(xia)(xia)(xia)(xia)，板(ban)(ban)(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)(pi)邊(bian)部(bu)出現(xian)拉應(ying)(ying)力(li)，引起邊(bian)部(bu)拉伸，板(ban)(ban)(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)(pi)通(tong)過(guo)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)(ping)(ping)面(mian)之后（通(tong)過(guo)孔型(xing)后），原來產生(sheng)(sheng)縱向(xiang)(xiang)扭(niu)(niu)曲(qu)(qu)(qu)(qu)(qu)的(de)(de)(de)(de)邊(bian)部(bu)被(bei)拉平(ping)(ping)(ping)(ping)(ping)，輥(gun)(gun)(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)(ping)(ping)面(mian)前(qian)(qian)(qian)(qian)變(bian)(bian)(bian)(bian)(bian)形(xing)區長(chang)度不(bu)再(zai)增加(jia)而保(bao)持(chi)長(chang)度不(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(pi)料橫截面(mian)各個直線(xian)部分受縱向拉伸或(huo)壓縮變(bian)形(xing)，與之相(xiang)鄰的(de)曲(qu)線(xian)部分受彎(wan)曲(qu)變(bian)形(xing)，弄清(qing)板坯(pi)在(zai)相(xiang)鄰兩道次間彎(wan)曲(qu)變(bian)形(xing)行為，對于制定成型(xing)方案和設計孔(kong)型(xing)具有一(yi)定的(de)意義。

為將板帶材經連續(xu)輥彎(wan)變形加工成合格冷彎(wan)型鋼而進行(xing)的成型方法及工具的設(she)計稱(cheng)為冷彎(wan)成型輥孔(kong)型設(she)計。冷彎(wan)成型輥孔(kong)型設(she)計的依(yi)據是：冷彎(wan)型材產(chan)品標準、成型材料的性能(neng)、技(ji)術要求、生(sheng)產(chan)機組配置及主(zhu)要參數。

1. 孔型(xing)設計的要求

 ①. 能夠(gou)生產出符合技(ji)術要(yao)求的(de)產品(pin)斷面形狀及尺寸精度(du)。

 ②. 產品在全長上無水(shui)平垂直瓢曲及(ji)縱向扭轉(zhuan)。

 ③. 彎折處減薄及斷面(mian)殘余應(ying)力最小，產品(pin)無(wu)邊(bian)波、皺折及裂(lie)紋。

 ④. 金屬出人孔型(xing)順利(li)，軋輥安裝調整方便。

 ⑤. 孔型組合配置合理、孔型磨(mo)損小、輥(gun)耗低、能耗小。

 ⑥. 操作方便，可達最(zui)大機組生產率(lv)。

2. 冷彎成型(xing)輥孔型(xing)設計步驟

 ①. 確定坯料(liao)寬度。

 ②. 確定型鋼(gang)對(dui)水平(ping)輥(gun)中(zhong)心線的位置。

 ③. 選擇型鋼(gang)成型基(ji)本中心線(xian)（簡稱基(ji)軸）及基(ji)準線(xian)段。

 ④. 確(que)定(ding)型鋼(gang)過(guo)渡斷面(mian)數(shu)量和(he)形(xing)狀（俗稱花形(xing)圖(tu)）。

 ⑤. 畫斷面配輥(gun)圖(tu)和單個(ge)軋輥(gun)及輥(gun)片圖(tu)。

 ⑥. 導衛及輔助工具(ju)設計(ji)及圖紙的繪(hui)制。

 ⑦. 必(bi)要(yao)的校核。