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)為異向性(xing)的(de)材料深拉深成(cheng)形特性(xing)評價的(de)重要指標(biao)。鐵素體系列不銹鋼中,其平(ping)均r值越大,其極(ji)限拉深比就越高。
c. 拉深(shen)皺折-鐵素體系列不銹鋼在(zai)沖床上進行深(shen)拉深(shen)加工時,在(zai)其表(biao)面上容易產生凹凸不平的皺折。可(ke)認為是組合結構不同而引起的塑性(xing)異向性(xing)。
d. 時(shi)效性斷裂-奧氏體(ti)系(xi)列不銹鋼SUS304等準(zhun)穩定型奧氏體(ti)系(xi)列不銹鋼,在加(jia)工(gong)后有發生時(shi)效性裂紋的現象。它與晶界(jie)晶粒無(wu)關。一(yi)般認為是由于加(jia)工(gong)感(gan)應(ying)而引起(qi)的馬氏體(ti)、氫和殘余應(ying)力所(suo)致。
1. 沖壓加工
沖(chong)壓(ya)(ya)加(jia)(jia)(jia)工(gong)(gong)行業(ye)是家(jia)庭(ting)式作坊(fang)工(gong)(gong)業(ye)的(de)代表(biao)性產(chan)業(ye),多是從(cong)單獨一(yi)個一(yi)個地(di)加(jia)(jia)(jia)工(gong)(gong)西餐(can)具(ju)、器(qi)(qi)皿(min)等所謂的(de)“洋人(ren)筷子”等開始,發展到餐(can)飲業(ye)的(de)廚房(fang)用(yong)具(ju)以(yi)及(ji)廚房(fang)中所使用(yong)的(de)水槽、洗滌盆、深拉(la)深加(jia)(jia)(jia)工(gong)(gong)的(de)澡盆以(yi)及(ji)汽車、電機(ji)領域中的(de)零(ling)部件等。主(zhu)要(yao)工(gong)(gong)藝方法是采用(yong)剪(jian)切、沖(chong)孔、拉(la)深等進(jin)行連續加(jia)(jia)(jia)工(gong)(gong)。洋餐(can)具(ju)、器(qi)(qi)皿(min)和(he)鍋的(de)沖(chong)壓(ya)(ya)加(jia)(jia)(jia)工(gong)(gong),基本上(shang)是屬于(yu)圓(yuan)筒(tong)拉(la)深制成(cheng)。原(yuan)材(cai)料(liao)板(ban)直(zhi)徑(jing)D對(dui)容器(qi)(qi)(產(chan)品)直(zhi)徑(jing)d之比,D/d稱為拉(la)深比。以(yi)可(ke)能(neng)拉(la)深的(de)最(zui)大原(yuan)材(cai)料(liao)板(ban)直(zhi)徑(jing)為Dmax時,則Dmax/d稱為極限(xian)拉(la)深比(LDR: Limiting Drawing Ratio)作為衡(heng)量加(jia)(jia)(jia)工(gong)(gong)性的(de)指(zhi)標。不(bu)銹(xiu)鋼(gang)產(chan)品得(de)以(yi)大幅(fu)度的(de)增(zeng)加(jia)(jia)(jia)需求與沖(chong)壓(ya)(ya)加(jia)(jia)(jia)工(gong)(gong)技術(shu)的(de)發展有很大關系。不(bu)銹(xiu)鋼(gang)產(chan)品生產(chan)廠家(jia)在(zai)深拉(la)深加(jia)(jia)(jia)工(gong)(gong)等方面(mian),由于(yu)塑性加(jia)(jia)(jia)工(gong)(gong)技術(shu)和(he)材(cai)料(liao)技術(shu)的(de)進(jin)展。使得(de)鐵素體系列不(bu)銹(xiu)鋼(gang)高加(jia)(jia)(jia)工(gong)(gong)性鋼(gang)種,已經產(chan)品化了(le)。可(ke)以(yi)選定平均r值在(zai)1.2~1.8,LDR為2.2~2.5的(de)鋼(gang)種。
在不銹鋼(gang)(gang)制品的(de)(de)沖壓加(jia)工(gong)中,如果使用奧氏體系列不銹鋼(gang)(gang)或鐵(tie)素體系列不銹鋼(gang)(gang)的(de)(de)高(gao)加(jia)工(gong)性能鋼(gang)(gang)種時,可以進(jin)行一定程度的(de)(de)深拉(la)深加(jia)工(gong)。奧氏體系列不銹鋼(gang)(gang)的(de)(de)代表型鋼(gang)(gang)種 SUS 304(18Cr -18Ni),因為(wei)它的(de)(de)LDR為(wei)2.5,可以進(jin)行相對(dui)較大的(de)(de)深拉(la)深加(jia)工(gong)。
但由于加工(gong)硬化傾向大而急劇地(di)增加了加工(gong)難(nan)度(du),有時(shi)竟發生裂(lie)紋(wen)或斷裂(lie)。為此(ci),沖(chong)壓廠家就在中間加上一道熱(re)處理(li)工(gong)序(xu)之后再進行深(shen)拉深(shen)加工(gong)。還必須注意,奧(ao)氏體系列(lie)不銹(xiu)鋼的奧(ao)氏體穩定度(du)低的鋼種經過拉深(shen)后,有可(ke)能發生時(shi)效(xiao)斷裂(lie)現(xian)象。

近年來,新潟縣燕市的(de)(de)沖(chong)(chong)壓加工(gong)(gong)廠和新鴻縣工(gong)(gong)業(ye)技術中心共同開發不銹鋼(gang)熱沖(chong)(chong)壓技術,實現了超深拉深加工(gong)(gong)。熱沖(chong)(chong)壓技術就(jiu)(jiu)是將凹(ao)模或者凸模其中之一進行加熱,這樣(yang)不銹鋼(gang)原(yuan)來的(de)(de)拉深程度就(jiu)(jiu)可以(yi)提(ti)高(gao)1.5~2.0倍。熱沖(chong)(chong)壓加工(gong)(gong)設備(bei)的(de)(de)工(gong)(gong)作原(yuan)理(li)如(ru)圖(tu)6-9所(suo)示(shi)。其加工(gong)(gong)特性如(ru)圖(tu)6-10所(suo)示(shi)。
2. 彎(wan)曲與連續沖裁
奧氏(shi)(shi)體(ti)(ti)系(xi)列不(bu)銹(xiu)鋼(gang)(gang)進(jin)(jin)行彎(wan)(wan)(wan)曲加(jia)(jia)工(gong)(gong)(gong)(gong)是(shi)(shi)件簡單(dan)之(zhi)事,可以(yi)制作角鋼(gang)(gang)、槽鋼(gang)(gang)等型材(cai)(cai)使用(yong)。鐵素體(ti)(ti)系(xi)列,馬(ma)氏(shi)(shi)體(ti)(ti)系(xi)列不(bu)銹(xiu)鋼(gang)(gang)作為(wei)(wei)(wei)型材(cai)(cai)加(jia)(jia)工(gong)(gong)(gong)(gong),一般(ban)情(qing)況下沒有問(wen)題,但(dan)(dan)當彎(wan)(wan)(wan)曲半徑R小的(de)(de)(de)時(shi)候(hou),在(zai)折彎(wan)(wan)(wan)處(chu)有時(shi)會發(fa)(fa)生(sheng)斷(duan)裂。在(zai)JIS標準(zhun)中,對鐵素體(ti)(ti)、馬(ma)氏(shi)(shi)體(ti)(ti)系(xi)列的(de)(de)(de)不(bu)銹(xiu)鋼(gang)(gang)彎(wan)(wan)(wan)曲試(shi)驗標準(zhun)規定,彎(wan)(wan)(wan)曲半徑R為(wei)(wei)(wei)1.0t(t為(wei)(wei)(wei)板材(cai)(cai)厚(hou)度(du))不(bu)應發(fa)(fa)生(sheng)彎(wan)(wan)(wan)曲斷(duan)裂。還(huan)有,必須注意(yi)不(bu)銹(xiu)鋼(gang)(gang)彎(wan)(wan)(wan)曲加(jia)(jia)工(gong)(gong)(gong)(gong)回彈量(liang)大的(de)(de)(de)特點。落(luo)料(liao)(liao)(俗稱下料(liao)(liao))或稱為(wei)(wei)(wei)沖(chong)裁加(jia)(jia)工(gong)(gong)(gong)(gong),大多數(shu)是(shi)(shi)采用(yong)沖(chong)床(chuang)連續加(jia)(jia)工(gong)(gong)(gong)(gong)的(de)(de)(de)方(fang)式(shi),有時(shi)在(zai)沖(chong)切斷(duan)面(mian)上,發(fa)(fa)生(sheng)塌邊(bian)現象(即沖(chong)切面(mian)與基準(zhun)平面(mian)不(bu)垂直)。精(jing)密落(luo)料(liao)(liao)是(shi)(shi)從變壓器(qi)等使用(yong)疊(die)層的(de)(de)(de)電(dian)磁(ci)鋼(gang)(gang)板的(de)(de)(de)加(jia)(jia)工(gong)(gong)(gong)(gong)技(ji)術(shu)(shu)開展起(qi)來的(de)(de)(de)技(ji)術(shu)(shu),對粒子加(jia)(jia)速器(qi)的(de)(de)(de)套環(collar)或電(dian)子零部件中的(de)(de)(de)引線框(lead frame)等等,從較厚(hou)的(de)(de)(de)板材(cai)(cai)到超薄(bo)(bo)材(cai)(cai),精(jing)密落(luo)料(liao)(liao)得到廣泛應用(yong)。沖(chong)壓加(jia)(jia)工(gong)(gong)(gong)(gong)機械亦(yi)可以(yi)進(jin)(jin)行精(jing)密沖(chong)壓(落(luo)料(liao)(liao))加(jia)(jia)工(gong)(gong)(gong)(gong),但(dan)(dan)由于(yu)沖(chong)壓塌邊(bian)的(de)(de)(de)問(wen)題,一般(ban)不(bu)能作為(wei)(wei)(wei)成品(pin)直接使用(yong)。在(zai)精(jing)密沖(chong)壓中,為(wei)(wei)(wei)控(kong)制塌邊(bian),就需(xu)加(jia)(jia)一道機械控(kong)制的(de)(de)(de)工(gong)(gong)(gong)(gong)藝措施,這需(xu)要按產品(pin)用(yong)途以(yi)及成本兩方(fang)面(mian)來權(quan)衡。在(zai)加(jia)(jia)工(gong)(gong)(gong)(gong)方(fang)法(fa)競(jing)爭(zheng)上,還(huan)有一種“蝕刻”方(fang)法(fa),在(zai)電(dian)子產品(pin)的(de)(de)(de)接線框等超薄(bo)(bo)產品(pin)中,在(zai)加(jia)(jia)工(gong)(gong)(gong)(gong)廠(chang)家的(de)(de)(de)技(ji)術(shu)(shu)競(jing)爭(zheng)中,兩者幾乎各(ge)占一半。
3. 加工油、表面保護(hu)薄(bo)膜和其他潤滑
a. 表面保護(hu)薄膜(mo)-為(wei)了保持不銹鋼的(de)匠藝性、防止產生瑕疵以(yi)及作為(wei)潤滑而敷(fu)于(yu)材料表面的(de)聚氯乙烯或(huo)聚乙烯等(deng)薄膜(mo)。
b. 揮(hui)發(fa)性加(jia)工油(you)--加(jia)工時有潤滑(hua)效果而后又能揮(hui)發(fa)掉的加(jia)工油(you)。使用完全(quan)揮(hui)發(fa)型的,可以(yi)省掉清洗工序(xu)。
c. 潤滑(hua)不(bu)銹(xiu)鋼(gang)板-具有透明石(shi)蠟涂裝的(de)(de)不(bu)銹(xiu)鋼(gang),它比加(jia)工(gong)油或表面(mian)保護(hu)膜有更好的(de)(de)加(jia)工(gong)性。
在(zai)沖(chong)床上進(jin)行(xing)不銹鋼(gang)板(ban)彎(wan)曲、沖(chong)裁(cai)(落料)等(deng)加(jia)工(gong)時,可使用加(jia)工(gong)油、表(biao)(biao)面(mian)(mian)(mian)保(bao)(bao)護(hu)薄膜(mo)(mo)(mo)或(huo)(huo)直接使用潤(run)滑鋼(gang)板(ban)。在(zai)表(biao)(biao)6-1中,對(dui)(dui)(dui)加(jia)工(gong)油、表(biao)(biao)面(mian)(mian)(mian)保(bao)(bao)護(hu)薄膜(mo)(mo)(mo)和潤(run)滑鋼(gang)板(ban)進(jin)行(xing)比(bi)較。表(biao)(biao)面(mian)(mian)(mian)保(bao)(bao)護(hu)薄膜(mo)(mo)(mo)是不銹鋼(gang)保(bao)(bao)持匠(jiang)藝性(xing)(xing)的一(yi)項重要措(cuo)施。所用樹脂為聚氯乙烯(xi)系列或(huo)(huo)聚乙烯(xi)系列。材料運轉自(zi)始至終都是用表(biao)(biao)面(mian)(mian)(mian)保(bao)(bao)護(hu)薄膜(mo)(mo)(mo)對(dui)(dui)(dui)材料表(biao)(biao)面(mian)(mian)(mian)施行(xing)保(bao)(bao)護(hu)。使用表(biao)(biao)面(mian)(mian)(mian)保(bao)(bao)護(hu)薄膜(mo)(mo)(mo),最容(rong)易發生(sheng)(sheng)的問題就(jiu)是殘留糊(hu)狀物(wu),貼附后(hou)長期(qi)保(bao)(bao)存在(zai)倉庫(ku)內的或(huo)(huo)者是不具備耐候性(xing)(xing)能(neng)的薄膜(mo)(mo)(mo)放置在(zai)室外的,則(ze)容(rong)易發生(sheng)(sheng)損壞(huai)(huai)。表(biao)(biao)面(mian)(mian)(mian)保(bao)(bao)護(hu)薄膜(mo)(mo)(mo)要根據用途和加(jia)工(gong)方(fang)法選定。主(zhu)要廠(chang)家生(sheng)(sheng)產的表(biao)(biao)面(mian)(mian)(mian)保(bao)(bao)護(hu)薄膜(mo)(mo)(mo)性(xing)(xing)能(neng)及其有關事項如表(biao)(biao)6-2所示(shi)。不使用表(biao)(biao)面(mian)(mian)(mian)保(bao)(bao)護(hu)薄膜(mo)(mo)(mo)時,一(yi)般情(qing)況下要使用加(jia)工(gong)油。當使用加(jia)工(gong)油加(jia)工(gong)后(hou),需進(jin)行(xing)洗凈(jing)。洗凈(jing)的方(fang)法有多種,最近在(zai)保(bao)(bao)護(hu)地球環(huan)境問題當中,規定了(le)保(bao)(bao)護(hu)環(huan)境條例,對(dui)(dui)(dui)于(yu)破壞(huai)(huai)臭(chou)氧層的清洗劑做出了(le)限制。


因此,當(dang)使用加(jia)(jia)(jia)(jia)(jia)工(gong)(gong)(gong)油(you)時,要(yao)考慮到洗凈和存放問題。在(zai)加(jia)(jia)(jia)(jia)(jia)工(gong)(gong)(gong)油(you)選(xuan)定(ding)方(fang)面,從前認為(wei)由于不(bu)銹鋼(gang)硬(ying)度(du)(du)比(bi)普通鋼(gang)要(yao)高,加(jia)(jia)(jia)(jia)(jia)工(gong)(gong)(gong)不(bu)銹鋼(gang)比(bi)普通鋼(gang)困難(nan),所以(yi)要(yao)選(xuan)用有(you)黏性(xing)(xing)的(de)加(jia)(jia)(jia)(jia)(jia)工(gong)(gong)(gong)油(you)。具有(you)黏性(xing)(xing)的(de)加(jia)(jia)(jia)(jia)(jia)工(gong)(gong)(gong)油(you)往往是黏糊(hu)糊(hu)的(de),在(zai)加(jia)(jia)(jia)(jia)(jia)工(gong)(gong)(gong)過程(cheng)中(zhong)不(bu)但變黑而且難(nan)以(yi)清洗。另外(wai),其(qi)中(zhong)多數情況下加(jia)(jia)(jia)(jia)(jia)入氯系(xi)列(lie)添加(jia)(jia)(jia)(jia)(jia)劑。因此,更有(you)必(bi)要(yao)進(jin)行充(chong)分地(di)清洗。近年來(lai),開發(fa)了許(xu)多水溶性(xing)(xing)加(jia)(jia)(jia)(jia)(jia)工(gong)(gong)(gong)油(you),在(zai)深拉深等加(jia)(jia)(jia)(jia)(jia)工(gong)(gong)(gong)中(zhong),其(qi)潤滑性(xing)(xing)堪比(bi)原用油(you)性(xing)(xing)的(de)加(jia)(jia)(jia)(jia)(jia)工(gong)(gong)(gong)油(you)。水溶性(xing)(xing)加(jia)(jia)(jia)(jia)(jia)工(gong)(gong)(gong)油(you)比(bi)較容易(yi)清洗,應(ying)用效果(guo)很好。作為(wei)新技術,雖然加(jia)(jia)(jia)(jia)(jia)工(gong)(gong)(gong)條件受到某種(zhong)程(cheng)度(du)(du)的(de)限制,免清洗的(de)揮發(fa)型(xing)加(jia)(jia)(jia)(jia)(jia)工(gong)(gong)(gong)油(you)仍得到推廣(guang)。
在揮(hui)發(fa)(fa)性加(jia)(jia)工(gong)油中,有(you)完全揮(hui)發(fa)(fa)型和(he)部分(fen)殘(can)留(liu)型等(deng)產(chan)品。需根據加(jia)(jia)工(gong)條件選擇,使用(yong)(yong)完全揮(hui)發(fa)(fa)型的可以省(sheng)掉(diao)加(jia)(jia)工(gong)后的清洗(xi)(xi)。在家電生產(chan)廠中,沖制(zhi)(zhi)全自動(dong)洗(xi)(xi)衣機(ji)不銹鋼洗(xi)(xi)衣桶時就是采(cai)用(yong)(yong)完全揮(hui)發(fa)(fa)型加(jia)(jia)工(gong)油。在其(qi)他領(ling)域(yu)中,完全揮(hui)發(fa)(fa)型加(jia)(jia)工(gong)油已(yi)實際運用(yong)(yong)到沖孔、內緣翻邊(bian)、壓制(zhi)(zhi)筋板、彎曲和(he)卷邊(bian)等(deng)沖壓工(gong)藝中。

由于使用揮發(fa)性(xing)加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)油(you)(you)可以(yi)省掉(diao)清(qing)洗(xi)工(gong)(gong)(gong)(gong)(gong)序,在流(liu)水加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)作(zuo)業線上(shang)使用,可以(yi)降低成本。主(zhu)要生產(chan)廠(chang)家的揮發(fa)性(xing)加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)油(you)(you)產(chan)品如表(biao)6-3所(suo)示。如將揮發(fa)性(xing)加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)油(you)(you)的涂(tu)敷方式和加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)條件(jian)進行改進時,即可以(yi)完全(quan)省掉(diao)清(qing)洗(xi)工(gong)(gong)(gong)(gong)(gong)作(zuo)。但(dan)是,揮發(fa)性(xing)加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)油(you)(you)涂(tu)敷方式、加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)條件(jian)及加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)夾具的質量(liang)管理不善時,由于加(jia)(jia)(jia)(jia)工(gong)(gong)(gong)(gong)(gong)夾具的磨(mo)損(sun)等可能產(chan)生對不銹鋼(gang)的鐵粉銹蝕(shi)事故。關(guan)于鐵粉銹蝕(shi)檢(jian)查(cha)方法,可參照本書后(hou)部章(zhang)節中的“使用時注意重占(zhan)日惠執處理”由的說明(ming)。
先前在(zai)沖(chong)壓加工(gong)(gong)過程中(zhong)使用加工(gong)(gong)油。為(wei)了洗(xi)凈這些加工(gong)(gong)油而(er)使用了破壞臭(chou)氧層的(de)三(san)氯(lv)乙烷,三(san)氯(lv)乙烯等。后來,洗(xi)凈方(fang)(fang)法(fa)改為(wei)堿性洗(xi)凈方(fang)(fang)法(fa)。在(zai)1995年(nian),考慮到保護地球(qiu)環境問(wen)題(ti),開發(fa)了潤滑(hua)不(bu)(bu)銹鋼板。在(zai)汽(qi)車、電機(ji)、燃氣器具領(ling)域中(zhong),積(ji)極推廣了省掉清洗(xi)工(gong)(gong)序(xu)的(de)潤滑(hua)不(bu)(bu)銹鋼板。特別是(shi)在(zai)汽(qi)車領(ling)域中(zhong)的(de)排(pai)氣分支管(guan)的(de)不(bu)(bu)銹鋼化(hua)過程中(zhong),實踐證明(ming),加工(gong)(gong)這種形(xing)狀復雜的(de)工(gong)(gong)件,認(ren)為(wei)潤滑(hua)不(bu)(bu)銹鋼板比以(yi)前使用潤滑(hua)油的(de)加工(gong)(gong)性更(geng)優越。所以(yi),潤滑(hua)不(bu)(bu)銹鋼板的(de)需要量大(da)幅度增加。

潤(run)(run)(run)滑(hua)不銹鋼(gang)(gang)(gang)板(ban),根據用(yong)途(tu)亦(yi)有(you)不涂(tu)薄(bo)膜的(de)。非脫膜型和脫膜型兩(liang)類已經產品(pin)化了(le)。潤(run)(run)(run)滑(hua)不銹鋼(gang)(gang)(gang)板(ban)種類和特性(xing)如(ru)表6-4所(suo)示。在建筑(zhu)材料領(ling)域中,使用(yong)潤(run)(run)(run)滑(hua)不銹鋼(gang)(gang)(gang)板(ban)做(zuo)屋頂(ding)時,非脫膜型和脫膜型一樣,其(qi)薄(bo)膜經過1~2年的(de)紫外線照射就消失了(le)。作為工程實例,用(yong)于西武百貨(huo)大(da)樓和福岡(gang)機場(chang)候機大(da)廳。實踐證明,潤(run)(run)(run)滑(hua)不銹鋼(gang)(gang)(gang)板(ban)的(de)加(jia)(jia)工性(xing)比加(jia)(jia)工油還要(yao)優越,見表6-5。
不(bu)銹(xiu)鋼板生產廠家的潤滑(hua)不(bu)銹(xiu)鋼板產品,在透明涂裝不(bu)銹(xiu)鋼項目中有介紹。

