將板、帶鋼在輥式(shi)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)式冷(leng)彎(wan)(wan)(wan)成(cheng)型(xing)(xing)(xing)和(he)(he)普通軋(ya)(ya)(ya)(ya)制過程(cheng)一(yi)樣，冷(leng)彎(wan)(wan)(wan)成(cheng)型(xing)(xing)(xing)時(shi)(shi)帶(dai)(dai)坯(pi)(pi)(pi)(pi)(pi)(pi)任(ren)意斷面(mian)(mian)上(shang)(shang)(shang)的(de)(de)(de)(de)(de)金(jin)(jin)屬(shu)流動是穩(wen)定的(de)(de)(de)(de)(de)，不(bu)(bu)隨(sui)時(shi)(shi)間(jian)而(er)變(bian)(bian)化，相鄰兩(liang)道次(ci)之間(jian)帶(dai)(dai)坯(pi)(pi)(pi)(pi)(pi)(pi)進入軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)位(wei)置(zhi)，如圖5-10所示，彎(wan)(wan)(wan)曲(qu)(qu)角由(you)上(shang)(shang)(shang)一(yi)道次(ci)的(de)(de)(de)(de)(de)αn-1增大到下(xia)(xia)一(yi)道次(ci)的(de)(de)(de)(de)(de)αn,彎(wan)(wan)(wan)曲(qu)(qu)圓(yuan)(yuan)弧半徑(jing)由(you)rn-1,減小(xiao)為(wei)rn.由(you)于板(ban)(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)前(qian)(qian)端(duan)部(bu)(bu)(bu)上(shang)(shang)(shang)拾，彎(wan)(wan)(wan)曲(qu)(qu)角增大，而(er)產(chan)(chan)生(sheng)(sheng)的(de)(de)(de)(de)(de)張力作(zuo)用(yong)于邊(bian)部(bu)(bu)(bu)，在(zai)(zai)(zai)相對(dui)旋(xuan)轉的(de)(de)(de)(de)(de)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)的(de)(de)(de)(de)(de)作(zuo)用(yong)下(xia)(xia)，板(ban)(ban)帶(dai)(dai)坯(pi)(pi)(pi)(pi)(pi)(pi)沿(yan)軋(ya)(ya)(ya)(ya)制方向(xiang)(xiang)前(qian)(qian)進并實現(xian)(xian)彎(wan)(wan)(wan)曲(qu)(qu)變(bian)(bian)形(xing)。實現(xian)(xian)板(ban)(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)彎(wan)(wan)(wan)曲(qu)(qu)變(bian)(bian)形(xing)的(de)(de)(de)(de)(de)軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)工作(zuo)部(bu)(bu)(bu)分(fen)稱(cheng)為(wei)軋(ya)(ya)(ya)(ya)槽(cao)（輥(gun)(gun)(gun)槽(cao)），由(you)兩(liang)個(ge)和(he)(he)兩(liang)個(ge)以上(shang)(shang)(shang)通過軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)(ping)(ping)面(mian)(mian)所構成(cheng)的(de)(de)(de)(de)(de)軋(ya)(ya)(ya)(ya)槽(cao)斷面(mian)(mian)變(bian)(bian)形(xing)區(qu)稱(cheng)為(wei)孔(kong)型(xing)(xing)(xing)。因(yin)此(ci)，輥(gun)(gun)(gun)式冷(leng)彎(wan)(wan)(wan)成(cheng)型(xing)(xing)(xing)亦可(ke)視為(wei)板(ban)(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)經若干孔(kong)型(xing)(xing)(xing)實現(xian)(xian)彎(wan)(wan)(wan)曲(qu)(qu)的(de)(de)(de)(de)(de)穩(wen)態(tai)變(bian)(bian)形(xing)過程(cheng)。從(cong)上(shang)(shang)(shang)一(yi)道輥(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)(ping)(ping)面(mian)(mian)（孔(kong)型(xing)(xing)(xing)）到下(xia)(xia)一(yi)道輥(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)(ping)(ping)面(mian)(mian)（孔(kong)型(xing)(xing)(xing)）間(jian)距(ju)離L稱(cheng)為(wei)平(ping)(ping)(ping)(ping)(ping)緩(huan)(huan)過渡區(qu)長度。L的(de)(de)(de)(de)(de)大小(xiao)與機架間(jian)距(ju)有關，L愈大變(bian)(bian)形(xing)愈緩(huan)(huan)和(he)(he)。而(er)平(ping)(ping)(ping)(ping)(ping)緩(huan)(huan)過渡區(qu)又可(ke)細(xi)分(fen)為(wei)L1和(he)(he)L2兩(liang)個(ge)區(qu)（見圖5-11).板(ban)(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)從(cong)前(qian)(qian)道孔(kong)型(xing)(xing)(xing)（對(dui)應(ying)(ying)彎(wan)(wan)(wan)曲(qu)(qu)角an-1)進入下(xia)(xia)道孔(kong)型(xing)(xing)(xing)（對(dui)應(ying)(ying)彎(wan)(wan)(wan)曲(qu)(qu)角αn),開始時(shi)(shi)坯(pi)(pi)(pi)(pi)(pi)(pi)料(liao)(liao)前(qian)(qian)端(duan)部(bu)(bu)(bu)分(fen)與軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)下(xia)(xia)軋(ya)(ya)(ya)(ya)槽(cao)接(jie)觸，在(zai)(zai)(zai)坯(pi)(pi)(pi)(pi)(pi)(pi)料(liao)(liao)中(zhong)形(xing)成(cheng)數值不(bu)(bu)大的(de)(de)(de)(de)(de)彈性應(ying)(ying)力。軋(ya)(ya)(ya)(ya)件前(qian)(qian)行與上(shang)(shang)(shang)軋(ya)(ya)(ya)(ya)槽(cao)接(jie)觸，在(zai)(zai)(zai)上(shang)(shang)(shang)下(xia)(xia)軋(ya)(ya)(ya)(ya)槽(cao)作(zuo)用(yong)下(xia)(xia)產(chan)(chan)生(sheng)(sheng)塑性彎(wan)(wan)(wan)曲(qu)(qu)，即板(ban)(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)在(zai)(zai)(zai)輥(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)(ping)(ping)面(mian)(mian)前(qian)(qian)（未通過an孔(kong)型(xing)(xing)(xing)）已(yi)開始了(le)塑性彎(wan)(wan)(wan)曲(qu)(qu)變(bian)(bian)形(xing)，原來(lai)平(ping)(ping)(ping)(ping)(ping)直的(de)(de)(de)(de)(de)邊(bian)部(bu)(bu)(bu)產(chan)(chan)生(sheng)(sheng)縱(zong)向(xiang)(xiang)扭曲(qu)(qu)，形(xing)成(cheng)復雜的(de)(de)(de)(de)(de)曲(qu)(qu)線表面(mian)(mian)。坯(pi)(pi)(pi)(pi)(pi)(pi)料(liao)(liao)的(de)(de)(de)(de)(de)橫截面(mian)(mian)形(xing)狀(zhuang)逐漸按孔(kong)型(xing)(xing)(xing)輪廓形(xing)狀(zhuang)變(bian)(bian)化。彎(wan)(wan)(wan)折處金(jin)(jin)屬(shu)連續經受彈性到彈塑性變(bian)(bian)形(xing)。隨(sui)彎(wan)(wan)(wan)曲(qu)(qu)角增大，彎(wan)(wan)(wan)曲(qu)(qu)圓(yuan)(yuan)弧半徑(jing)減小(xiao)，彎(wan)(wan)(wan)折處切向(xiang)(xiang)正應(ying)(ying)力和(he)(he)彎(wan)(wan)(wan)矩增加，在(zai)(zai)(zai)板(ban)(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)料(liao)(liao)前(qian)(qian)端(duan)已(yi)變(bian)(bian)形(xing)部(bu)(bu)(bu)分(fen)與軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)壓緊軋(ya)(ya)(ya)(ya)件的(de)(de)(de)(de)(de)共同作(zuo)用(yong)下(xia)(xia)，板(ban)(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)邊(bian)部(bu)(bu)(bu)出現(xian)(xian)拉應(ying)(ying)力，引起邊(bian)部(bu)(bu)(bu)拉伸，板(ban)(ban)坯(pi)(pi)(pi)(pi)(pi)(pi)通過軋(ya)(ya)(ya)(ya)輥(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)(ping)(ping)面(mian)(mian)之后(hou)（通過孔(kong)型(xing)(xing)(xing)后(hou)），原來(lai)產(chan)(chan)生(sheng)(sheng)縱(zong)向(xiang)(xiang)扭曲(qu)(qu)的(de)(de)(de)(de)(de)邊(bian)部(bu)(bu)(bu)被拉平(ping)(ping)(ping)(ping)(ping)，輥(gun)(gun)(gun)軸(zhou)平(ping)(ping)(ping)(ping)(ping)面(mian)(mian)前(qian)(qian)變(bian)(bian)形(xing)區(qu)長度不(bu)(bu)再增加而(er)保持(chi)長度不(bu)(bu)變(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(mian)各個直線部分(fen)受(shou)縱向拉伸或壓縮變形，與之相鄰的曲線部分(fen)受(shou)彎(wan)曲變形，弄清板坯在(zai)相鄰兩道次間彎(wan)曲變形行為(wei)，對于(yu)制定成型方案和設計孔型具有一定的意義。

為(wei)將板(ban)帶材經連(lian)續(xu)輥(gun)彎(wan)變形(xing)加工(gong)成合格(ge)冷彎(wan)型(xing)鋼(gang)而進行的(de)成型(xing)方(fang)法及工(gong)具的(de)設計稱(cheng)為(wei)冷彎(wan)成型(xing)輥(gun)孔(kong)型(xing)設計。冷彎(wan)成型(xing)輥(gun)孔(kong)型(xing)設計的(de)依據(ju)是：冷彎(wan)型(xing)材產(chan)品(pin)標(biao)準、成型(xing)材料的(de)性能、技術(shu)要求、生產(chan)機組配置及主要參數。

1. 孔型設計的要求

 ①. 能夠生產出符合技(ji)術要求的產品斷面(mian)形狀(zhuang)及尺寸精度(du)。

 ②. 產品在(zai)全長上無水平(ping)垂直瓢曲及縱向扭轉(zhuan)。

 ③. 彎折處(chu)減(jian)薄及斷面(mian)殘余應力最(zui)小(xiao)，產品無邊波、皺折及裂紋。

 ④. 金屬(shu)出人(ren)孔型順利，軋輥安(an)裝調(diao)整方便。

 ⑤. 孔型組(zu)合配置(zhi)合理、孔型磨損小(xiao)、輥耗低、能耗小(xiao)。

 ⑥. 操作方便，可達最大機組生產率(lv)。

2. 冷彎成型輥孔型設計步(bu)驟(zou)

 ①. 確定坯料寬度。

 ②. 確定型鋼對水平輥(gun)中心線(xian)的位(wei)置。

 ③. 選擇型鋼成(cheng)型基本中(zhong)心線（簡(jian)稱基軸）及基準線段(duan)。

 ④. 確定型鋼過渡斷面數量和形狀（俗稱花形圖）。

 ⑤. 畫斷面配輥圖(tu)和單個軋(ya)輥及(ji)輥片圖(tu)。

 ⑥. 導衛(wei)及(ji)輔助(zhu)工具設計及(ji)圖紙的繪制。

 ⑦. 必要的(de)校核。