首先想了解不銹鋼沖壓、彎曲和連續沖裁加工工藝,必須要知道以下幾點:
a. 極限拉深比--拉深加工時,相對于容器直徑d可能拉深的最大原料板直徑為Dmax時,Dmax/d則稱為極限拉深比(LDR).
b. 平(ping)均r值--塑性(xing)為(wei)異向性(xing)的材(cai)料深拉深成形特(te)性(xing)評價的重要指標(biao)。鐵(tie)素體系列不銹(xiu)鋼(gang)中,其平(ping)均r值越大(da),其極(ji)限拉深比就(jiu)越高。
c. 拉(la)深(shen)皺折-鐵素體系列(lie)不(bu)銹(xiu)鋼在沖(chong)床上(shang)進行深(shen)拉(la)深(shen)加工時,在其表面上(shang)容易產生凹凸不(bu)平的皺折。可(ke)認為是組合結(jie)構不(bu)同而引起的塑性異向(xiang)性。
d. 時(shi)效(xiao)性斷裂-奧(ao)(ao)氏體(ti)系(xi)列不銹(xiu)鋼(gang)SUS304等(deng)準穩(wen)定型(xing)奧(ao)(ao)氏體(ti)系(xi)列不銹(xiu)鋼(gang),在加(jia)工(gong)后有發生時(shi)效(xiao)性裂紋(wen)的(de)現象。它與(yu)晶(jing)(jing)界晶(jing)(jing)粒(li)無關。一般認為是由于(yu)加(jia)工(gong)感(gan)應(ying)而引(yin)起的(de)馬氏體(ti)、氫和殘余應(ying)力所致(zhi)。
1. 沖壓加工
沖(chong)(chong)壓加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)行業(ye)是(shi)家庭式(shi)作(zuo)(zuo)坊(fang)工(gong)(gong)(gong)(gong)(gong)業(ye)的(de)(de)(de)代(dai)表性(xing)產(chan)業(ye),多是(shi)從單獨一個(ge)一個(ge)地加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)西餐(can)(can)具(ju)(ju)、器(qi)皿等(deng)(deng)所謂的(de)(de)(de)“洋(yang)人筷子”等(deng)(deng)開始,發展到餐(can)(can)飲(yin)業(ye)的(de)(de)(de)廚房(fang)用(yong)具(ju)(ju)以(yi)及廚房(fang)中(zhong)所使用(yong)的(de)(de)(de)水(shui)槽、洗滌盆、深(shen)(shen)拉(la)(la)深(shen)(shen)加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)的(de)(de)(de)澡盆以(yi)及汽車(che)、電機領域中(zhong)的(de)(de)(de)零部件等(deng)(deng)。主要(yao)工(gong)(gong)(gong)(gong)(gong)藝方法是(shi)采用(yong)剪切、沖(chong)(chong)孔(kong)、拉(la)(la)深(shen)(shen)等(deng)(deng)進行連續(xu)加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)。洋(yang)餐(can)(can)具(ju)(ju)、器(qi)皿和鍋的(de)(de)(de)沖(chong)(chong)壓加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong),基本上是(shi)屬(shu)于圓筒拉(la)(la)深(shen)(shen)制(zhi)成。原(yuan)材(cai)(cai)料板直徑(jing)D對容器(qi)(產(chan)品)直徑(jing)d之比(bi)(bi),D/d稱(cheng)為(wei)拉(la)(la)深(shen)(shen)比(bi)(bi)。以(yi)可(ke)能(neng)拉(la)(la)深(shen)(shen)的(de)(de)(de)最大(da)原(yuan)材(cai)(cai)料板直徑(jing)為(wei)Dmax時,則Dmax/d稱(cheng)為(wei)極限(xian)拉(la)(la)深(shen)(shen)比(bi)(bi)(LDR: Limiting Drawing Ratio)作(zuo)(zuo)為(wei)衡量加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)性(xing)的(de)(de)(de)指標。不銹(xiu)(xiu)鋼(gang)產(chan)品得以(yi)大(da)幅度的(de)(de)(de)增加(jia)(jia)(jia)(jia)需求與沖(chong)(chong)壓加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)技(ji)(ji)術的(de)(de)(de)發展有(you)很大(da)關系。不銹(xiu)(xiu)鋼(gang)產(chan)品生(sheng)產(chan)廠家在(zai)深(shen)(shen)拉(la)(la)深(shen)(shen)加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)等(deng)(deng)方面(mian),由于塑性(xing)加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)技(ji)(ji)術和材(cai)(cai)料技(ji)(ji)術的(de)(de)(de)進展。使得鐵素體系列(lie)不銹(xiu)(xiu)鋼(gang)高加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)性(xing)鋼(gang)種,已經(jing)產(chan)品化了。可(ke)以(yi)選(xuan)定平均r值在(zai)1.2~1.8,LDR為(wei)2.2~2.5的(de)(de)(de)鋼(gang)種。
在不(bu)(bu)(bu)銹(xiu)鋼(gang)制品(pin)的(de)(de)沖(chong)壓(ya)加(jia)工中,如果(guo)使(shi)用奧氏體系(xi)列(lie)不(bu)(bu)(bu)銹(xiu)鋼(gang)或鐵素體系(xi)列(lie)不(bu)(bu)(bu)銹(xiu)鋼(gang)的(de)(de)高加(jia)工性(xing)能鋼(gang)種(zhong)(zhong)時,可(ke)以進行(xing)(xing)一定程度的(de)(de)深拉深加(jia)工。奧氏體系(xi)列(lie)不(bu)(bu)(bu)銹(xiu)鋼(gang)的(de)(de)代表型鋼(gang)種(zhong)(zhong) SUS 304(18Cr -18Ni),因為它的(de)(de)LDR為2.5,可(ke)以進行(xing)(xing)相對(dui)較大的(de)(de)深拉深加(jia)工。
但由于加(jia)(jia)工硬(ying)化(hua)傾向(xiang)大(da)而急劇地增加(jia)(jia)了加(jia)(jia)工難度(du),有(you)時竟發生裂紋(wen)或斷(duan)裂。為此,沖壓廠家就在中間加(jia)(jia)上一道熱處理工序之(zhi)后再進行深拉深加(jia)(jia)工。還必(bi)須注意,奧氏體系列不(bu)銹鋼的奧氏體穩定度(du)低的鋼種經過拉深后,有(you)可能發生時效斷(duan)裂現象(xiang)。
近(jin)年來(lai),新潟縣(xian)燕市的(de)(de)沖(chong)壓(ya)(ya)加(jia)工廠和新鴻縣(xian)工業技術(shu)中(zhong)(zhong)心共(gong)同開(kai)發不銹鋼熱(re)沖(chong)壓(ya)(ya)技術(shu),實現(xian)了超深(shen)拉深(shen)加(jia)工。熱(re)沖(chong)壓(ya)(ya)技術(shu)就是將凹模(mo)或者凸模(mo)其中(zhong)(zhong)之一(yi)進行加(jia)熱(re),這(zhe)樣不銹鋼原(yuan)來(lai)的(de)(de)拉深(shen)程(cheng)度就可以提高1.5~2.0倍。熱(re)沖(chong)壓(ya)(ya)加(jia)工設備(bei)的(de)(de)工作原(yuan)理如圖(tu)6-9所示。其加(jia)工特性如圖(tu)6-10所示。
2. 彎曲與連續沖裁
奧氏(shi)(shi)體(ti)(ti)系(xi)列不(bu)銹鋼進行彎(wan)(wan)曲(qu)加(jia)工(gong)(gong)(gong)是(shi)件(jian)簡單(dan)之事(shi),可以(yi)制作(zuo)角鋼、槽鋼等(deng)(deng)(deng)型材使用(yong)。鐵素體(ti)(ti)系(xi)列,馬氏(shi)(shi)體(ti)(ti)系(xi)列不(bu)銹鋼作(zuo)為型材加(jia)工(gong)(gong)(gong),一般情況下沒有問題,但當彎(wan)(wan)曲(qu)半徑(jing)R小的(de)時候(hou),在(zai)(zai)折(zhe)彎(wan)(wan)處有時會發生(sheng)(sheng)斷(duan)裂。在(zai)(zai)JIS標(biao)(biao)準(zhun)中,對鐵素體(ti)(ti)、馬氏(shi)(shi)體(ti)(ti)系(xi)列的(de)不(bu)銹鋼彎(wan)(wan)曲(qu)試驗(yan)標(biao)(biao)準(zhun)規定(ding),彎(wan)(wan)曲(qu)半徑(jing)R為1.0t(t為板材厚度)不(bu)應發生(sheng)(sheng)彎(wan)(wan)曲(qu)斷(duan)裂。還有,必須注意不(bu)銹鋼彎(wan)(wan)曲(qu)加(jia)工(gong)(gong)(gong)回(hui)彈量大的(de)特點。落(luo)料(liao)(俗稱(cheng)下料(liao))或稱(cheng)為沖(chong)裁(cai)加(jia)工(gong)(gong)(gong),大多(duo)數是(shi)采用(yong)沖(chong)床連續加(jia)工(gong)(gong)(gong)的(de)方(fang)式,有時在(zai)(zai)沖(chong)切(qie)(qie)斷(duan)面(mian)上,發生(sheng)(sheng)塌(ta)邊現象(即沖(chong)切(qie)(qie)面(mian)與基準(zhun)平(ping)面(mian)不(bu)垂直(zhi))。精(jing)(jing)密(mi)落(luo)料(liao)是(shi)從(cong)變壓(ya)(ya)(ya)器等(deng)(deng)(deng)使用(yong)疊(die)層的(de)電(dian)磁鋼板的(de)加(jia)工(gong)(gong)(gong)技術(shu)開展起來的(de)技術(shu),對粒子(zi)加(jia)速器的(de)套環(huan)(collar)或電(dian)子(zi)零部(bu)件(jian)中的(de)引線框(kuang)(lead frame)等(deng)(deng)(deng)等(deng)(deng)(deng),從(cong)較厚的(de)板材到(dao)超薄材,精(jing)(jing)密(mi)落(luo)料(liao)得到(dao)廣泛應用(yong)。沖(chong)壓(ya)(ya)(ya)加(jia)工(gong)(gong)(gong)機(ji)械亦可以(yi)進行精(jing)(jing)密(mi)沖(chong)壓(ya)(ya)(ya)(落(luo)料(liao))加(jia)工(gong)(gong)(gong),但由于沖(chong)壓(ya)(ya)(ya)塌(ta)邊的(de)問題,一般不(bu)能作(zuo)為成品(pin)直(zhi)接使用(yong)。在(zai)(zai)精(jing)(jing)密(mi)沖(chong)壓(ya)(ya)(ya)中,為控(kong)制塌(ta)邊,就需加(jia)一道(dao)機(ji)械控(kong)制的(de)工(gong)(gong)(gong)藝措施(shi),這需要按產(chan)品(pin)用(yong)途以(yi)及成本兩(liang)方(fang)面(mian)來權衡(heng)。在(zai)(zai)加(jia)工(gong)(gong)(gong)方(fang)法競爭(zheng)上,還有一種“蝕刻”方(fang)法,在(zai)(zai)電(dian)子(zi)產(chan)品(pin)的(de)接線框(kuang)等(deng)(deng)(deng)超薄產(chan)品(pin)中,在(zai)(zai)加(jia)工(gong)(gong)(gong)廠家的(de)技術(shu)競爭(zheng)中,兩(liang)者(zhe)幾乎各(ge)占(zhan)一半。
3. 加工油、表面保護薄膜和(he)其他(ta)潤(run)滑
a. 表面保(bao)護薄膜-為(wei)了保(bao)持不銹鋼的匠藝性、防止產(chan)生瑕疵以及(ji)作為(wei)潤滑而敷于(yu)材料表面的聚氯乙烯或聚乙烯等薄膜。
b. 揮(hui)發性加工(gong)油--加工(gong)時有潤滑效果而后又(you)能揮(hui)發掉(diao)的加工(gong)油。使用完(wan)全揮(hui)發型的,可以省掉(diao)清洗工(gong)序。
c. 潤滑不(bu)銹鋼(gang)板-具有透(tou)明石(shi)蠟涂(tu)裝(zhuang)的不(bu)銹鋼(gang),它比加工油或表面保(bao)護膜有更好的加工性。
在沖(chong)床(chuang)上進行不銹鋼(gang)(gang)板(ban)彎曲、沖(chong)裁(落料(liao))等加(jia)工時(shi),可使用(yong)加(jia)工油、表(biao)(biao)(biao)(biao)面(mian)保(bao)(bao)(bao)護(hu)(hu)薄(bo)(bo)(bo)(bo)膜(mo)(mo)(mo)(mo)或(huo)直接使用(yong)潤滑(hua)鋼(gang)(gang)板(ban)。在表(biao)(biao)(biao)(biao)6-1中,對加(jia)工油、表(biao)(biao)(biao)(biao)面(mian)保(bao)(bao)(bao)護(hu)(hu)薄(bo)(bo)(bo)(bo)膜(mo)(mo)(mo)(mo)和潤滑(hua)鋼(gang)(gang)板(ban)進行比較。表(biao)(biao)(biao)(biao)面(mian)保(bao)(bao)(bao)護(hu)(hu)薄(bo)(bo)(bo)(bo)膜(mo)(mo)(mo)(mo)是(shi)不銹鋼(gang)(gang)保(bao)(bao)(bao)持匠藝性的(de)(de)(de)一(yi)(yi)項重要措施(shi)(shi)。所用(yong)樹(shu)脂(zhi)為聚氯乙烯(xi)系列或(huo)聚乙烯(xi)系列。材(cai)料(liao)運轉自始至終都是(shi)用(yong)表(biao)(biao)(biao)(biao)面(mian)保(bao)(bao)(bao)護(hu)(hu)薄(bo)(bo)(bo)(bo)膜(mo)(mo)(mo)(mo)對材(cai)料(liao)表(biao)(biao)(biao)(biao)面(mian)施(shi)(shi)行保(bao)(bao)(bao)護(hu)(hu)。使用(yong)表(biao)(biao)(biao)(biao)面(mian)保(bao)(bao)(bao)護(hu)(hu)薄(bo)(bo)(bo)(bo)膜(mo)(mo)(mo)(mo),最(zui)容易發生(sheng)的(de)(de)(de)問題(ti)就(jiu)是(shi)殘留糊狀(zhuang)物,貼附后長(chang)期保(bao)(bao)(bao)存在倉庫內的(de)(de)(de)或(huo)者是(shi)不具備耐候(hou)性能(neng)的(de)(de)(de)薄(bo)(bo)(bo)(bo)膜(mo)(mo)(mo)(mo)放置在室外的(de)(de)(de),則(ze)容易發生(sheng)損壞。表(biao)(biao)(biao)(biao)面(mian)保(bao)(bao)(bao)護(hu)(hu)薄(bo)(bo)(bo)(bo)膜(mo)(mo)(mo)(mo)要根據用(yong)途和加(jia)工方法選定(ding)(ding)。主(zhu)要廠家生(sheng)產(chan)的(de)(de)(de)表(biao)(biao)(biao)(biao)面(mian)保(bao)(bao)(bao)護(hu)(hu)薄(bo)(bo)(bo)(bo)膜(mo)(mo)(mo)(mo)性能(neng)及其有關事項如表(biao)(biao)(biao)(biao)6-2所示。不使用(yong)表(biao)(biao)(biao)(biao)面(mian)保(bao)(bao)(bao)護(hu)(hu)薄(bo)(bo)(bo)(bo)膜(mo)(mo)(mo)(mo)時(shi),一(yi)(yi)般情(qing)況下要使用(yong)加(jia)工油。當使用(yong)加(jia)工油加(jia)工后,需進行洗(xi)凈(jing)。洗(xi)凈(jing)的(de)(de)(de)方法有多種(zhong),最(zui)近(jin)在保(bao)(bao)(bao)護(hu)(hu)地球環(huan)境問題(ti)當中,規定(ding)(ding)了(le)保(bao)(bao)(bao)護(hu)(hu)環(huan)境條例(li),對于破(po)壞臭氧層的(de)(de)(de)清洗(xi)劑做出了(le)限(xian)制。
因此,當使(shi)用(yong)加(jia)(jia)(jia)工(gong)(gong)油(you)(you)(you)(you)(you)時,要(yao)(yao)考(kao)慮到洗凈(jing)和存放問題。在(zai)加(jia)(jia)(jia)工(gong)(gong)油(you)(you)(you)(you)(you)選定方面,從前(qian)認(ren)為由于(yu)不(bu)銹(xiu)鋼(gang)硬(ying)度(du)比普通(tong)鋼(gang)要(yao)(yao)高,加(jia)(jia)(jia)工(gong)(gong)不(bu)銹(xiu)鋼(gang)比普通(tong)鋼(gang)困難,所以(yi)要(yao)(yao)選用(yong)有(you)黏(nian)性的(de)(de)加(jia)(jia)(jia)工(gong)(gong)油(you)(you)(you)(you)(you)。具(ju)有(you)黏(nian)性的(de)(de)加(jia)(jia)(jia)工(gong)(gong)油(you)(you)(you)(you)(you)往往是黏(nian)糊糊的(de)(de),在(zai)加(jia)(jia)(jia)工(gong)(gong)過程(cheng)中不(bu)但變(bian)黑(hei)而且難以(yi)清(qing)(qing)洗。另外,其中多數情(qing)況下加(jia)(jia)(jia)入(ru)氯系列添加(jia)(jia)(jia)劑。因此,更有(you)必(bi)要(yao)(yao)進行充分地清(qing)(qing)洗。近年來,開發了許多水溶性加(jia)(jia)(jia)工(gong)(gong)油(you)(you)(you)(you)(you),在(zai)深拉深等加(jia)(jia)(jia)工(gong)(gong)中,其潤滑性堪比原用(yong)油(you)(you)(you)(you)(you)性的(de)(de)加(jia)(jia)(jia)工(gong)(gong)油(you)(you)(you)(you)(you)。水溶性加(jia)(jia)(jia)工(gong)(gong)油(you)(you)(you)(you)(you)比較(jiao)容易清(qing)(qing)洗,應用(yong)效果(guo)很好。作為新技術,雖然加(jia)(jia)(jia)工(gong)(gong)條件受到某(mou)種程(cheng)度(du)的(de)(de)限制,免(mian)清(qing)(qing)洗的(de)(de)揮發型(xing)加(jia)(jia)(jia)工(gong)(gong)油(you)(you)(you)(you)(you)仍得到推廣(guang)。
在揮(hui)發(fa)性加工油(you)中,有完全(quan)(quan)揮(hui)發(fa)型(xing)(xing)(xing)和部分(fen)殘留型(xing)(xing)(xing)等產品(pin)。需根據(ju)加工條件選擇,使用完全(quan)(quan)揮(hui)發(fa)型(xing)(xing)(xing)的可(ke)以(yi)省(sheng)掉(diao)加工后的清洗。在家電生產廠中,沖制全(quan)(quan)自動洗衣機不(bu)銹鋼洗衣桶時就是采(cai)用完全(quan)(quan)揮(hui)發(fa)型(xing)(xing)(xing)加工油(you)。在其他領域中,完全(quan)(quan)揮(hui)發(fa)型(xing)(xing)(xing)加工油(you)已(yi)實際運(yun)用到(dao)沖孔、內緣翻(fan)邊、壓(ya)制筋板、彎曲(qu)和卷(juan)邊等沖壓(ya)工藝中。
由于使(shi)用(yong)揮(hui)發性(xing)加(jia)工油(you)可(ke)以(yi)(yi)省(sheng)掉清洗工序,在(zai)流水加(jia)工作業線上使(shi)用(yong),可(ke)以(yi)(yi)降低成本(ben)。主要生產(chan)廠家的揮(hui)發性(xing)加(jia)工油(you)產(chan)品如表6-3所(suo)示。如將揮(hui)發性(xing)加(jia)工油(you)的涂敷方(fang)式(shi)和加(jia)工條(tiao)(tiao)件進(jin)行改進(jin)時(shi)(shi),即可(ke)以(yi)(yi)完全省(sheng)掉清洗工作。但是,揮(hui)發性(xing)加(jia)工油(you)涂敷方(fang)式(shi)、加(jia)工條(tiao)(tiao)件及加(jia)工夾具(ju)(ju)的質量管(guan)理不善時(shi)(shi),由于加(jia)工夾具(ju)(ju)的磨(mo)損等可(ke)能產(chan)生對不銹(xiu)鋼(gang)的鐵(tie)粉銹(xiu)蝕(shi)事故(gu)。關于鐵(tie)粉銹(xiu)蝕(shi)檢查(cha)方(fang)法(fa),可(ke)參照本(ben)書后部章(zhang)節中的“使(shi)用(yong)時(shi)(shi)注意重(zhong)占日惠執處理”由的說明。
先前在沖壓加(jia)(jia)工(gong)(gong)過程中(zhong)使(shi)用(yong)加(jia)(jia)工(gong)(gong)油(you)。為(wei)了(le)洗凈(jing)這(zhe)些加(jia)(jia)工(gong)(gong)油(you)而使(shi)用(yong)了(le)破(po)壞臭(chou)氧層的(de)三氯乙(yi)烷,三氯乙(yi)烯等。后(hou)來,洗凈(jing)方法改為(wei)堿(jian)性(xing)洗凈(jing)方法。在1995年,考慮到保(bao)護(hu)地球環境問(wen)題,開發了(le)潤(run)(run)(run)滑不(bu)銹(xiu)鋼(gang)板(ban)(ban)。在汽車、電(dian)機、燃氣(qi)器具(ju)領域中(zhong),積極推廣(guang)了(le)省掉清(qing)洗工(gong)(gong)序的(de)潤(run)(run)(run)滑不(bu)銹(xiu)鋼(gang)板(ban)(ban)。特別是在汽車領域中(zhong)的(de)排氣(qi)分支管的(de)不(bu)銹(xiu)鋼(gang)化(hua)過程中(zhong),實踐(jian)證明,加(jia)(jia)工(gong)(gong)這(zhe)種形(xing)狀復(fu)雜的(de)工(gong)(gong)件,認為(wei)潤(run)(run)(run)滑不(bu)銹(xiu)鋼(gang)板(ban)(ban)比以(yi)前使(shi)用(yong)潤(run)(run)(run)滑油(you)的(de)加(jia)(jia)工(gong)(gong)性(xing)更優(you)越。所以(yi),潤(run)(run)(run)滑不(bu)銹(xiu)鋼(gang)板(ban)(ban)的(de)需要量大幅度增(zeng)加(jia)(jia)。
潤(run)(run)滑(hua)(hua)不銹鋼(gang)板,根據用(yong)途亦有不涂(tu)薄膜(mo)的(de)。非脫膜(mo)型和(he)脫膜(mo)型兩(liang)類(lei)已經(jing)產品化了。潤(run)(run)滑(hua)(hua)不銹鋼(gang)板種類(lei)和(he)特性如表6-4所示(shi)。在(zai)建(jian)筑材料領域中,使(shi)用(yong)潤(run)(run)滑(hua)(hua)不銹鋼(gang)板做屋頂(ding)時,非脫膜(mo)型和(he)脫膜(mo)型一樣,其薄膜(mo)經(jing)過1~2年(nian)的(de)紫外線照射就消失了。作為(wei)工(gong)程實例,用(yong)于西武百貨大樓和(he)福岡機場候機大廳(ting)。實踐證明(ming),潤(run)(run)滑(hua)(hua)不銹鋼(gang)板的(de)加(jia)(jia)工(gong)性比(bi)加(jia)(jia)工(gong)油還(huan)要優越(yue),見表6-5。
不(bu)銹(xiu)鋼板生產廠(chang)家的潤滑不(bu)銹(xiu)鋼板產品,在透明涂裝不(bu)銹(xiu)鋼項目中(zhong)有介紹。