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(yi)(yi)般(ban)每架成(cheng)型(xing)機(ji)裝(zhuang)有一(yi)(yi)對(dui)或多(duo)對(dui)成(cheng)型(xing)輥,每列成(cheng)型(xing)機(ji)組由兩(liang)架以上的(de)成(cheng)型(xing)機(ji)組線(xian)。在輥式(shi)冷彎(wan)成(cheng)型(xing)過程(cheng)中(zhong)(zhong)只(zhi)有彎(wan)曲變(bian)(bian)形(xing)。除(chu)坯料彎(wan)曲角局部(bu)有輕(qing)微(wei)減薄外,變(bian)(bian)形(xing)材料的(de)厚度在成(cheng)型(xing)過程(cheng)中(zhong)(zhong)保持不變(bian)(bian)。這種加工方法特別(bie)適合于外形(xing)縱長、批量較大的(de)高精度產品的(de)加工,此外,在輥式(shi)冷彎(wan)成(cheng)型(xing)過程(cheng)中(zhong)(zhong),可以很容易(yi)地將沖裁(cai)、打(da)孔、壓印、縱彎(wan)等輔助加工引入進來(lai)。
輥式(shi)冷彎(wan)成型(xing)工(gong)藝(yi)可(ke)分為四(si)種(zhong)(zhong),即(ji)單張(或(huo)單件)成型(xing)工(gong)藝(yi)、成卷成型(xing)工(gong)藝(yi)、連續成型(xing)工(gong)藝(yi)和聯合加工(gong)工(gong)藝(yi)。每一種(zhong)(zhong)工(gong)藝(yi)都可(ke)分為3個階(jie)段,即(ji)成型(xing)前坯料準備階(jie)段、成型(xing)加工(gong)階(jie)段、型(xing)材精(jing)整階(jie)段。
單(dan)張成(cheng)(cheng)型(xing)工(gong)(gong)藝就是預定(ding)尺坯(pi)料(liao)(liao)的(de)(de)成(cheng)(cheng)型(xing)方(fang)(fang)法(fa)。這(zhe)(zhe)種(zhong)方(fang)(fang)法(fa)在坯(pi)料(liao)(liao)成(cheng)(cheng)型(xing)之前將坯(pi)料(liao)(liao)切成(cheng)(cheng)定(ding)尺長度(du),然后(hou)用送料(liao)(liao)輥(gun)(gun)將坯(pi)料(liao)(liao)送進(jin)成(cheng)(cheng)型(xing)輥(gun)(gun),成(cheng)(cheng)型(xing)后(hou)的(de)(de)型(xing)材(cai)不必經剪切即可收集入庫(ku)。采(cai)用這(zhe)(zhe)種(zhong)成(cheng)(cheng)型(xing)工(gong)(gong)藝的(de)(de)成(cheng)(cheng)型(xing)輥(gun)(gun)的(de)(de)速度(du)一般在15~75m/min.這(zhe)(zhe)種(zhong)工(gong)(gong)藝主要(yao)應用于(yu)小批量、成(cheng)(cheng)型(xing)后(hou)型(xing)材(cai)鋸切比較(jiao)困(kun)難(nan)的(de)(de)情況下。采(cai)用單(dan)張成(cheng)(cheng)型(xing)工(gong)(gong)藝成(cheng)(cheng)型(xing)機組的(de)(de)設備(bei)較(jiao)簡單(dan)、工(gong)(gong)具(ju)費(fei)用少、投資低。但用這(zhe)(zhe)種(zhong)生產工(gong)(gong)藝得到(dao)的(de)(de)型(xing)材(cai)邊部縱向拉伸較(jiao)大,因而只有(you)利用側立(li)輥(gun)(gun)才能(neng)得到(dao)比較(jiao)精確的(de)(de)產品形。
成卷(juan)(juan)成型(xing)(xing)工(gong)藝(yi)和連(lian)(lian)(lian)續(xu)成型(xing)(xing)工(gong)藝(yi)基本相(xiang)同,所不(bu)同的(de)(de)是(shi)連(lian)(lian)(lian)續(xu)成型(xing)(xing)時(shi)(shi)前一(yi)卷(juan)(juan)帶材的(de)(de)尾部與(yu)后一(yi)卷(juan)(juan)帶材的(de)(de)頭部經(jing)過齊(qi)對焊,使坯(pi)料帶材連(lian)(lian)(lian)續(xu)不(bu)斷地進(jin)人成型(xing)(xing)機進(jin)行成型(xing)(xing)。而成卷(juan)(juan)成型(xing)(xing)時(shi)(shi)帶卷(juan)(juan)頭尾不(bu)對焊,進(jin)行單(dan)卷(juan)(juan)供料成型(xing)(xing)。與(yu)單(dan)張(zhang)成型(xing)(xing)工(gong)藝(yi)相(xiang)比,這兩種(zhong)成型(xing)(xing)工(gong)藝(yi)更加(jia)高效、高產、通用。這兩種(zhong)成型(xing)(xing)工(gong)藝(yi)的(de)(de)主要(yao)優點是(shi):
①. 帶卷成(cheng)本(ben)低、切損少,因而降低了材料(liao)總成(cheng)本(ben)。
②. 由于需要(yao)的成(cheng)型機架數少(shao)且(qie)不需要(yao)額(e)外的導衛裝(zhuang)置,因而工具成(cheng)本(ben)低。
③. 可以加工(gong)形(xing)狀比單張成型工(gong)藝更復(fu)雜的型材。
④. 型材的頭尾部扭曲及張開度減小。
⑤. 由(you)于(yu)操作幾乎(hu)是連續的(de),因(yin)而生產率得到(dao)提(ti)高(gao)。
但這兩(liang)種(zhong)(zhong)成(cheng)(cheng)型工藝(yi)需要開卷機(ji)、活套器、對焊機(ji)、定尺飛鋸或(huo)飛剪等輔助設(she)備(bei),因而(er)其機(ji)組(zu)設(she)備(bei)投資較大(da)、占地較大(da)。成(cheng)(cheng)型機(ji)組(zu)的(de)成(cheng)(cheng)型速度一般為30~90m/min.目前投產(chan)的(de)絕大(da)多數輥式冷彎成(cheng)(cheng)型機(ji)組(zu)均是采(cai)用這兩(liang)種(zhong)(zhong)工藝(yi),因此(ci)后面將(jiang)以這兩(liang)種(zhong)(zhong)成(cheng)(cheng)型工藝(yi)為例(li)進行重點闡述,圖5-1給出了其工藝(yi)流程示意(yi)圖。
聯(lian)合加工(gong)工(gong)藝用于加工(gong)具有特定要(yao)求的(de)冷(leng)(leng)(leng)彎(wan)型(xing)鋼(gang),如高(gao)強度(du)冷(leng)(leng)(leng)彎(wan)型(xing)鋼(gang)、閉口焊接(jie)冷(leng)(leng)(leng)彎(wan)型(xing)鋼(gang)、熱處(chu)理強化冷(leng)(leng)(leng)彎(wan)型(xing)鋼(gang)、周(zhou)期波紋板沖孔冷(leng)(leng)(leng)彎(wan)型(xing)鋼(gang),涂(tu)層冷(leng)(leng)(leng)彎(wan)型(xing)鋼(gang)等。聯(lian)合加工(gong)成型(xing)機(ji)組的(de)設備最復雜、投資最高(gao)。根據產品的(de)要(yao)求這種(zhong)機(ji)組可包括如下設備:直縫焊機(ji)、對焊機(ji)、輥(gun)(gun)式沖孔機(ji)、輥(gun)(gun)式壓(ya)印(yin)機(ji)、涂(tu)層機(ji)、熱處(chu)理設備等。
輥(gun)式(shi)冷(leng)彎(wan)成(cheng)型(xing)(xing)是(shi)用(yong)一(yi)組成(cheng)型(xing)(xing)輥(gun)將(jiang)帶材(cai)(cai)逐漸壓(ya)彎(wan)成(cheng)所(suo)需的(de)斷面型(xing)(xing)材(cai)(cai),現以冷(leng)彎(wan)角鋼(gang)為(wei)例,圖5-2是(shi)由4個機(ji)(ji)(ji)架(jia)(jia)組成(cheng)的(de)輥(gun)式(shi)冷(leng)彎(wan)成(cheng)型(xing)(xing)機(ji)(ji)(ji)組,第(di)一(yi)機(ji)(ji)(ji)架(jia)(jia)完成(cheng)帶材(cai)(cai)的(de)平(ping)整(zheng)和送進工作(zuo),第(di)二~第(di)四(si)機(ji)(ji)(ji)架(jia)(jia)各承擔一(yi)定的(de)壓(ya)彎(wan)成(cheng)型(xing)(xing)任務,使帶材(cai)(cai)通過后被(bei)彎(wan)曲壓(ya)制成(cheng)角型(xing)(xing)材(cai)(cai)。每一(yi)對成(cheng)型(xing)(xing)輥(gun)所(suo)分擔的(de)彎(wan)曲變(bian)形量,決定了該機(ji)(ji)(ji)架(jia)(jia)孔型(xing)(xing)設(she)計(ji)的(de)基(ji)本尺寸。不過至今的(de)孔型(xing)(xing)設(she)計(ji)主(zhu)要還是(shi)依(yi)靠經(jing)驗的(de)積累,尚(shang)缺(que)乏(fa)理論解析方法。