輥式冷彎成型是以金屬薄板或帶卷為原料,并通過多架裝配了具有一定形狀的成型輥對坯料逐架次進行彎曲變形,從而得到均一最面的產品的塑性加工方法。
一般每架(jia)成型(xing)(xing)機(ji)裝有(you)一對或多對成型(xing)(xing)輥,每列成型(xing)(xing)機(ji)組(zu)由兩架(jia)以(yi)上的成型(xing)(xing)機(ji)組(zu)線。在(zai)輥式冷彎(wan)(wan)成型(xing)(xing)過程(cheng)中(zhong)只有(you)彎(wan)(wan)曲變(bian)形(xing)。除坯(pi)料彎(wan)(wan)曲角局部有(you)輕微(wei)減薄外,變(bian)形(xing)材料的厚度在(zai)成型(xing)(xing)過程(cheng)中(zhong)保持不變(bian)。這種加(jia)工方(fang)法(fa)特別適合(he)于外形(xing)縱長、批量(liang)較大的高精度產品的加(jia)工,此外,在(zai)輥式冷彎(wan)(wan)成型(xing)(xing)過程(cheng)中(zhong),可以(yi)很容易地將沖裁、打(da)孔、壓(ya)印、縱彎(wan)(wan)等輔助加(jia)工引入進來(lai)。
輥式冷彎成型工(gong)(gong)藝(yi)(yi)可分為四種,即(ji)單(dan)張(或(huo)單(dan)件)成型工(gong)(gong)藝(yi)(yi)、成卷成型工(gong)(gong)藝(yi)(yi)、連續成型工(gong)(gong)藝(yi)(yi)和聯(lian)合(he)加工(gong)(gong)工(gong)(gong)藝(yi)(yi)。每一種工(gong)(gong)藝(yi)(yi)都可分為3個階(jie)段(duan),即(ji)成型前坯料準備階(jie)段(duan)、成型加工(gong)(gong)階(jie)段(duan)、型材(cai)精整階(jie)段(duan)。
單張(zhang)成(cheng)(cheng)型(xing)(xing)(xing)(xing)工藝(yi)(yi)就是預定尺坯(pi)料的成(cheng)(cheng)型(xing)(xing)(xing)(xing)方(fang)(fang)法。這(zhe)種(zhong)方(fang)(fang)法在坯(pi)料成(cheng)(cheng)型(xing)(xing)(xing)(xing)之前(qian)將坯(pi)料切(qie)成(cheng)(cheng)定尺長度(du),然后(hou)(hou)用(yong)送料輥將坯(pi)料送進成(cheng)(cheng)型(xing)(xing)(xing)(xing)輥,成(cheng)(cheng)型(xing)(xing)(xing)(xing)后(hou)(hou)的型(xing)(xing)(xing)(xing)材(cai)不必經剪切(qie)即(ji)可收(shou)集入庫。采用(yong)這(zhe)種(zhong)成(cheng)(cheng)型(xing)(xing)(xing)(xing)工藝(yi)(yi)的成(cheng)(cheng)型(xing)(xing)(xing)(xing)輥的速(su)度(du)一般在15~75m/min.這(zhe)種(zhong)工藝(yi)(yi)主要應(ying)用(yong)于(yu)小批量、成(cheng)(cheng)型(xing)(xing)(xing)(xing)后(hou)(hou)型(xing)(xing)(xing)(xing)材(cai)鋸切(qie)比較(jiao)困難的情況下。采用(yong)單張(zhang)成(cheng)(cheng)型(xing)(xing)(xing)(xing)工藝(yi)(yi)成(cheng)(cheng)型(xing)(xing)(xing)(xing)機組的設(she)備較(jiao)簡單、工具費(fei)用(yong)少、投資低(di)。但用(yong)這(zhe)種(zhong)生產工藝(yi)(yi)得(de)到的型(xing)(xing)(xing)(xing)材(cai)邊部縱向拉伸較(jiao)大,因而只有(you)利(li)用(yong)側(ce)立輥才能得(de)到比較(jiao)精確(que)的產品(pin)形。
成(cheng)(cheng)(cheng)卷(juan)(juan)成(cheng)(cheng)(cheng)型工(gong)(gong)藝和連續(xu)成(cheng)(cheng)(cheng)型工(gong)(gong)藝基本相(xiang)同,所不同的(de)是(shi)連續(xu)成(cheng)(cheng)(cheng)型時(shi)前一(yi)卷(juan)(juan)帶(dai)材的(de)尾部與后一(yi)卷(juan)(juan)帶(dai)材的(de)頭部經過齊(qi)對焊,使坯料帶(dai)材連續(xu)不斷(duan)地進(jin)人(ren)成(cheng)(cheng)(cheng)型機(ji)進(jin)行(xing)成(cheng)(cheng)(cheng)型。而(er)成(cheng)(cheng)(cheng)卷(juan)(juan)成(cheng)(cheng)(cheng)型時(shi)帶(dai)卷(juan)(juan)頭尾不對焊,進(jin)行(xing)單卷(juan)(juan)供料成(cheng)(cheng)(cheng)型。與單張成(cheng)(cheng)(cheng)型工(gong)(gong)藝相(xiang)比,這兩(liang)種(zhong)成(cheng)(cheng)(cheng)型工(gong)(gong)藝更加高效(xiao)、高產、通(tong)用。這兩(liang)種(zhong)成(cheng)(cheng)(cheng)型工(gong)(gong)藝的(de)主要優點是(shi):
①. 帶卷成(cheng)(cheng)本(ben)低、切損少,因而(er)降低了材料總成(cheng)(cheng)本(ben)。
②. 由(you)于需要的成型機架數少且不需要額外的導衛裝置,因(yin)而工具成本低。
③. 可(ke)以(yi)加工形狀(zhuang)比單張成型工藝更復雜的型材(cai)。
④. 型(xing)材(cai)的頭(tou)尾部扭曲及張(zhang)開度(du)減(jian)小。
⑤. 由于操作幾乎是連續的,因而生(sheng)產率得到提高(gao)。
但這(zhe)兩種成(cheng)型(xing)工(gong)藝(yi)(yi)(yi)需要開卷機(ji)(ji)、活(huo)套器(qi)、對焊(han)機(ji)(ji)、定(ding)尺飛鋸(ju)或飛剪等輔助設備,因而其(qi)機(ji)(ji)組設備投資較(jiao)大(da)、占(zhan)地較(jiao)大(da)。成(cheng)型(xing)機(ji)(ji)組的成(cheng)型(xing)速(su)度一般為30~90m/min.目前投產的絕大(da)多數(shu)輥式冷彎成(cheng)型(xing)機(ji)(ji)組均是采用這(zhe)兩種工(gong)藝(yi)(yi)(yi),因此(ci)后面將以這(zhe)兩種成(cheng)型(xing)工(gong)藝(yi)(yi)(yi)為例進行重(zhong)點闡述,圖5-1給出了其(qi)工(gong)藝(yi)(yi)(yi)流程示意圖。
聯合加(jia)(jia)工工藝(yi)用(yong)于加(jia)(jia)工具有特定要(yao)求的冷(leng)(leng)(leng)彎(wan)(wan)型鋼(gang),如高強(qiang)度(du)冷(leng)(leng)(leng)彎(wan)(wan)型鋼(gang)、閉口(kou)焊(han)接冷(leng)(leng)(leng)彎(wan)(wan)型鋼(gang)、熱處理(li)強(qiang)化冷(leng)(leng)(leng)彎(wan)(wan)型鋼(gang)、周期波(bo)紋板沖孔(kong)冷(leng)(leng)(leng)彎(wan)(wan)型鋼(gang),涂層冷(leng)(leng)(leng)彎(wan)(wan)型鋼(gang)等。聯合加(jia)(jia)工成型機(ji)(ji)組(zu)的設備最復(fu)雜(za)、投資最高。根(gen)據產品的要(yao)求這種機(ji)(ji)組(zu)可(ke)包括如下設備:直縫焊(han)機(ji)(ji)、對焊(han)機(ji)(ji)、輥式沖孔(kong)機(ji)(ji)、輥式壓(ya)印(yin)機(ji)(ji)、涂層機(ji)(ji)、熱處理(li)設備等。
輥(gun)(gun)式冷彎成(cheng)型是用一(yi)組成(cheng)型輥(gun)(gun)將(jiang)帶(dai)材(cai)逐(zhu)漸壓(ya)(ya)彎成(cheng)所需的(de)斷面型材(cai),現以冷彎角鋼為(wei)例,圖(tu)5-2是由4個機(ji)(ji)(ji)架組成(cheng)的(de)輥(gun)(gun)式冷彎成(cheng)型機(ji)(ji)(ji)組,第(di)(di)一(yi)機(ji)(ji)(ji)架完成(cheng)帶(dai)材(cai)的(de)平整和送進工作,第(di)(di)二~第(di)(di)四機(ji)(ji)(ji)架各承擔一(yi)定(ding)的(de)壓(ya)(ya)彎成(cheng)型任務,使帶(dai)材(cai)通過(guo)后被(bei)彎曲壓(ya)(ya)制成(cheng)角型材(cai)。每一(yi)對(dui)成(cheng)型輥(gun)(gun)所分擔的(de)彎曲變形量(liang),決定(ding)了(le)該(gai)機(ji)(ji)(ji)架孔型設計的(de)基本尺寸。不(bu)過(guo)至今的(de)孔型設計主要還是依靠經(jing)驗的(de)積(ji)累,尚缺乏理論解析方法。