將板、帶鋼在輥式冷彎成(cheng)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(leng)彎(wan)(wan)(wan)成(cheng)型(xing)和(he)(he)(he)普通(tong)軋(ya)(ya)(ya)(ya)制(zhi)過(guo)(guo)(guo)程(cheng)一樣，冷(leng)彎(wan)(wan)(wan)成(cheng)型(xing)時(shi)帶坯(pi)(pi)(pi)任意斷面(mian)上(shang)(shang)(shang)的(de)(de)(de)(de)金屬流動是(shi)穩定的(de)(de)(de)(de)，不隨時(shi)間(jian)(jian)而(er)變(bian)(bian)(bian)化，相(xiang)鄰(lin)兩(liang)道(dao)(dao)次(ci)之間(jian)(jian)帶坯(pi)(pi)(pi)進(jin)(jin)入(ru)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)位置，如圖(tu)5-10所示，彎(wan)(wan)(wan)曲(qu)角(jiao)(jiao)由(you)上(shang)(shang)(shang)一道(dao)(dao)次(ci)的(de)(de)(de)(de)αn-1增(zeng)大到下(xia)一道(dao)(dao)次(ci)的(de)(de)(de)(de)αn,彎(wan)(wan)(wan)曲(qu)圓(yuan)弧半徑(jing)由(you)rn-1,減(jian)小(xiao)為rn.由(you)于(yu)板(ban)坯(pi)(pi)(pi)前(qian)(qian)端(duan)部(bu)(bu)上(shang)(shang)(shang)拾，彎(wan)(wan)(wan)曲(qu)角(jiao)(jiao)增(zeng)大，而(er)產(chan)生(sheng)的(de)(de)(de)(de)張(zhang)力作(zuo)用于(yu)邊部(bu)(bu)，在(zai)(zai)相(xiang)對(dui)(dui)旋(xuan)轉(zhuan)的(de)(de)(de)(de)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)的(de)(de)(de)(de)作(zuo)用下(xia)，板(ban)帶坯(pi)(pi)(pi)沿軋(ya)(ya)(ya)(ya)制(zhi)方向(xiang)前(qian)(qian)進(jin)(jin)并實(shi)(shi)現彎(wan)(wan)(wan)曲(qu)變(bian)(bian)(bian)形(xing)(xing)。實(shi)(shi)現板(ban)坯(pi)(pi)(pi)彎(wan)(wan)(wan)曲(qu)變(bian)(bian)(bian)形(xing)(xing)的(de)(de)(de)(de)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)工作(zuo)部(bu)(bu)分(fen)(fen)(fen)稱(cheng)為軋(ya)(ya)(ya)(ya)槽(cao)(cao)(cao)（輥(gun)(gun)(gun)(gun)槽(cao)(cao)(cao)），由(you)兩(liang)個(ge)和(he)(he)(he)兩(liang)個(ge)以上(shang)(shang)(shang)通(tong)過(guo)(guo)(guo)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)軸(zhou)(zhou)平(ping)(ping)(ping)面(mian)所構成(cheng)的(de)(de)(de)(de)軋(ya)(ya)(ya)(ya)槽(cao)(cao)(cao)斷面(mian)變(bian)(bian)(bian)形(xing)(xing)區(qu)(qu)稱(cheng)為孔(kong)(kong)(kong)(kong)型(xing)。因此(ci)，輥(gun)(gun)(gun)(gun)式冷(leng)彎(wan)(wan)(wan)成(cheng)型(xing)亦(yi)可視為板(ban)坯(pi)(pi)(pi)經若(ruo)干(gan)孔(kong)(kong)(kong)(kong)型(xing)實(shi)(shi)現彎(wan)(wan)(wan)曲(qu)的(de)(de)(de)(de)穩態(tai)變(bian)(bian)(bian)形(xing)(xing)過(guo)(guo)(guo)程(cheng)。從(cong)上(shang)(shang)(shang)一道(dao)(dao)輥(gun)(gun)(gun)(gun)軸(zhou)(zhou)平(ping)(ping)(ping)面(mian)（孔(kong)(kong)(kong)(kong)型(xing)）到下(xia)一道(dao)(dao)輥(gun)(gun)(gun)(gun)軸(zhou)(zhou)平(ping)(ping)(ping)面(mian)（孔(kong)(kong)(kong)(kong)型(xing)）間(jian)(jian)距離L稱(cheng)為平(ping)(ping)(ping)緩(huan)過(guo)(guo)(guo)渡(du)區(qu)(qu)長度。L的(de)(de)(de)(de)大小(xiao)與機(ji)架間(jian)(jian)距有關，L愈大變(bian)(bian)(bian)形(xing)(xing)愈緩(huan)和(he)(he)(he)。而(er)平(ping)(ping)(ping)緩(huan)過(guo)(guo)(guo)渡(du)區(qu)(qu)又可細分(fen)(fen)(fen)為L1和(he)(he)(he)L2兩(liang)個(ge)區(qu)(qu)（見圖(tu)5-11).板(ban)坯(pi)(pi)(pi)從(cong)前(qian)(qian)道(dao)(dao)孔(kong)(kong)(kong)(kong)型(xing)（對(dui)(dui)應(ying)彎(wan)(wan)(wan)曲(qu)角(jiao)(jiao)an-1)進(jin)(jin)入(ru)下(xia)道(dao)(dao)孔(kong)(kong)(kong)(kong)型(xing)（對(dui)(dui)應(ying)彎(wan)(wan)(wan)曲(qu)角(jiao)(jiao)αn),開(kai)始時(shi)坯(pi)(pi)(pi)料(liao)前(qian)(qian)端(duan)部(bu)(bu)分(fen)(fen)(fen)與軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)下(xia)軋(ya)(ya)(ya)(ya)槽(cao)(cao)(cao)接(jie)觸，在(zai)(zai)坯(pi)(pi)(pi)料(liao)中形(xing)(xing)成(cheng)數(shu)值不大的(de)(de)(de)(de)彈(dan)性應(ying)力。軋(ya)(ya)(ya)(ya)件前(qian)(qian)行與上(shang)(shang)(shang)軋(ya)(ya)(ya)(ya)槽(cao)(cao)(cao)接(jie)觸，在(zai)(zai)上(shang)(shang)(shang)下(xia)軋(ya)(ya)(ya)(ya)槽(cao)(cao)(cao)作(zuo)用下(xia)產(chan)生(sheng)塑(su)(su)性彎(wan)(wan)(wan)曲(qu)，即板(ban)坯(pi)(pi)(pi)在(zai)(zai)輥(gun)(gun)(gun)(gun)軸(zhou)(zhou)平(ping)(ping)(ping)面(mian)前(qian)(qian)（未通(tong)過(guo)(guo)(guo)an孔(kong)(kong)(kong)(kong)型(xing)）已(yi)開(kai)始了塑(su)(su)性彎(wan)(wan)(wan)曲(qu)變(bian)(bian)(bian)形(xing)(xing)，原來平(ping)(ping)(ping)直的(de)(de)(de)(de)邊部(bu)(bu)產(chan)生(sheng)縱向(xiang)扭曲(qu)，形(xing)(xing)成(cheng)復雜的(de)(de)(de)(de)曲(qu)線(xian)表面(mian)。坯(pi)(pi)(pi)料(liao)的(de)(de)(de)(de)橫截(jie)面(mian)形(xing)(xing)狀逐漸按孔(kong)(kong)(kong)(kong)型(xing)輪廓形(xing)(xing)狀變(bian)(bian)(bian)化。彎(wan)(wan)(wan)折處(chu)金屬連續(xu)經受(shou)彈(dan)性到彈(dan)塑(su)(su)性變(bian)(bian)(bian)形(xing)(xing)。隨彎(wan)(wan)(wan)曲(qu)角(jiao)(jiao)增(zeng)大，彎(wan)(wan)(wan)曲(qu)圓(yuan)弧半徑(jing)減(jian)小(xiao)，彎(wan)(wan)(wan)折處(chu)切向(xiang)正應(ying)力和(he)(he)(he)彎(wan)(wan)(wan)矩(ju)增(zeng)加，在(zai)(zai)板(ban)坯(pi)(pi)(pi)料(liao)前(qian)(qian)端(duan)已(yi)變(bian)(bian)(bian)形(xing)(xing)部(bu)(bu)分(fen)(fen)(fen)與軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)壓(ya)緊(jin)軋(ya)(ya)(ya)(ya)件的(de)(de)(de)(de)共(gong)同作(zuo)用下(xia)，板(ban)坯(pi)(pi)(pi)邊部(bu)(bu)出現拉應(ying)力，引起邊部(bu)(bu)拉伸，板(ban)坯(pi)(pi)(pi)通(tong)過(guo)(guo)(guo)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)(gun)軸(zhou)(zhou)平(ping)(ping)(ping)面(mian)之后(hou)（通(tong)過(guo)(guo)(guo)孔(kong)(kong)(kong)(kong)型(xing)后(hou)），原來產(chan)生(sheng)縱向(xiang)扭曲(qu)的(de)(de)(de)(de)邊部(bu)(bu)被拉平(ping)(ping)(ping)，輥(gun)(gun)(gun)(gun)軸(zhou)(zhou)平(ping)(ping)(ping)面(mian)前(qian)(qian)變(bian)(bian)(bian)形(xing)(xing)區(qu)(qu)長度不再增(zeng)加而(er)保持長度不變(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)橫截(jie)面各個直線(xian)部分(fen)受(shou)縱(zong)向拉伸或壓(ya)縮變(bian)形，與(yu)之相鄰的曲(qu)(qu)(qu)線(xian)部分(fen)受(shou)彎曲(qu)(qu)(qu)變(bian)形，弄清板坯(pi)在相鄰兩道次間彎曲(qu)(qu)(qu)變(bian)形行為(wei)，對于制(zhi)定(ding)成型(xing)方案(an)和設計孔型(xing)具(ju)有一(yi)定(ding)的意義(yi)。

為(wei)(wei)將(jiang)板帶材經(jing)連續(xu)輥彎變(bian)形加(jia)工(gong)成(cheng)(cheng)(cheng)合(he)格冷(leng)(leng)彎型(xing)(xing)鋼(gang)而進行的成(cheng)(cheng)(cheng)型(xing)(xing)方法及工(gong)具的設(she)計(ji)稱為(wei)(wei)冷(leng)(leng)彎成(cheng)(cheng)(cheng)型(xing)(xing)輥孔型(xing)(xing)設(she)計(ji)。冷(leng)(leng)彎成(cheng)(cheng)(cheng)型(xing)(xing)輥孔型(xing)(xing)設(she)計(ji)的依據是：冷(leng)(leng)彎型(xing)(xing)材產(chan)品標準(zhun)、成(cheng)(cheng)(cheng)型(xing)(xing)材料的性(xing)能、技術要求、生產(chan)機組配置(zhi)及主(zhu)要參數。

1. 孔型設計的要求(qiu)

 ①. 能夠生(sheng)產出符(fu)合技(ji)術要(yao)求的產品(pin)斷(duan)面形(xing)狀(zhuang)及尺寸精度(du)。

 ②. 產品在全長(chang)上(shang)無水平垂直瓢(piao)曲及縱向扭轉(zhuan)。

 ③. 彎折(zhe)處減薄及(ji)斷面殘余應力最(zui)小，產品無邊波、皺折(zhe)及(ji)裂紋。

 ④. 金屬出人孔型順利，軋輥安裝(zhuang)調整方便。

 ⑤. 孔型(xing)組合配(pei)置合理、孔型(xing)磨損小、輥耗低、能耗小。

 ⑥. 操作方便，可達最大機組生產(chan)率。

2. 冷彎成(cheng)型輥孔型設計步驟(zou)

 ①. 確定坯(pi)料寬度。

 ②. 確(que)定(ding)型(xing)鋼對水(shui)平輥(gun)中心線的位(wei)置(zhi)。

 ③. 選擇(ze)型鋼成型基本中(zhong)心線（簡稱基軸(zhou)）及基準線段。

 ④. 確定型(xing)鋼過渡斷面數(shu)量(liang)和形狀（俗稱花形圖）。

 ⑤. 畫斷面(mian)配輥圖(tu)和單個(ge)軋輥及(ji)輥片圖(tu)。

 ⑥. 導衛及輔助工具設計及圖(tu)紙的繪制。

 ⑦. 必(bi)要的校(xiao)核(he)。