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. 平均r值--塑性為(wei)異向性的材料深拉深成(cheng)形特性評(ping)價的重要指標。鐵素體(ti)系列(lie)不銹鋼(gang)中(zhong),其(qi)平均r值越(yue)大,其(qi)極(ji)限拉深比就(jiu)越(yue)高。
c. 拉深(shen)皺折(zhe)-鐵素體系列不(bu)(bu)銹鋼(gang)在沖床上進行(xing)深(shen)拉深(shen)加工時,在其表面上容易產生凹凸(tu)不(bu)(bu)平的皺折(zhe)。可認為是組合結(jie)構不(bu)(bu)同而(er)引起的塑性異(yi)向(xiang)性。
d. 時(shi)效(xiao)性斷裂-奧(ao)氏(shi)(shi)體(ti)系列不銹鋼(gang)SUS304等準穩(wen)定型奧(ao)氏(shi)(shi)體(ti)系列不銹鋼(gang),在加工(gong)后有發(fa)生時(shi)效(xiao)性裂紋(wen)的現象。它與晶界晶粒無關(guan)。一般認為是由于加工(gong)感(gan)應而引起(qi)的馬氏(shi)(shi)體(ti)、氫和殘余應力所致。
1. 沖壓加工
沖(chong)壓加(jia)(jia)工行業(ye)是家庭式作(zuo)坊工業(ye)的(de)(de)(de)(de)(de)代表性(xing)(xing)(xing)產(chan)(chan)業(ye),多是從單獨一個一個地加(jia)(jia)工西餐(can)具、器(qi)皿等(deng)所謂(wei)的(de)(de)(de)(de)(de)“洋人筷子”等(deng)開始,發(fa)展(zhan)到餐(can)飲業(ye)的(de)(de)(de)(de)(de)廚(chu)房(fang)用(yong)具以及廚(chu)房(fang)中所使用(yong)的(de)(de)(de)(de)(de)水槽、洗(xi)滌盆、深(shen)(shen)拉(la)(la)深(shen)(shen)加(jia)(jia)工的(de)(de)(de)(de)(de)澡盆以及汽車、電機領域中的(de)(de)(de)(de)(de)零(ling)部件等(deng)。主要(yao)工藝(yi)方法是采(cai)用(yong)剪切、沖(chong)孔(kong)、拉(la)(la)深(shen)(shen)等(deng)進(jin)行連續加(jia)(jia)工。洋餐(can)具、器(qi)皿和鍋的(de)(de)(de)(de)(de)沖(chong)壓加(jia)(jia)工,基本上是屬于(yu)圓(yuan)筒拉(la)(la)深(shen)(shen)制成。原材(cai)料板直(zhi)(zhi)徑(jing)D對容(rong)器(qi)(產(chan)(chan)品)直(zhi)(zhi)徑(jing)d之比(bi),D/d稱(cheng)為拉(la)(la)深(shen)(shen)比(bi)。以可能拉(la)(la)深(shen)(shen)的(de)(de)(de)(de)(de)最(zui)大原材(cai)料板直(zhi)(zhi)徑(jing)為Dmax時,則(ze)Dmax/d稱(cheng)為極(ji)限拉(la)(la)深(shen)(shen)比(bi)(LDR: Limiting Drawing Ratio)作(zuo)為衡(heng)量(liang)加(jia)(jia)工性(xing)(xing)(xing)的(de)(de)(de)(de)(de)指標。不銹鋼產(chan)(chan)品得以大幅(fu)度的(de)(de)(de)(de)(de)增加(jia)(jia)需求與(yu)沖(chong)壓加(jia)(jia)工技術的(de)(de)(de)(de)(de)發(fa)展(zhan)有很大關(guan)系。不銹鋼產(chan)(chan)品生產(chan)(chan)廠家在深(shen)(shen)拉(la)(la)深(shen)(shen)加(jia)(jia)工等(deng)方面,由于(yu)塑性(xing)(xing)(xing)加(jia)(jia)工技術和材(cai)料技術的(de)(de)(de)(de)(de)進(jin)展(zhan)。使得鐵素體系列不銹鋼高加(jia)(jia)工性(xing)(xing)(xing)鋼種,已經產(chan)(chan)品化了。可以選定(ding)平(ping)均r值在1.2~1.8,LDR為2.2~2.5的(de)(de)(de)(de)(de)鋼種。
在(zai)不(bu)(bu)銹(xiu)鋼(gang)(gang)(gang)(gang)制品的(de)沖壓加工(gong)(gong)中,如果(guo)使用奧氏體系(xi)列(lie)(lie)不(bu)(bu)銹(xiu)鋼(gang)(gang)(gang)(gang)或鐵素體系(xi)列(lie)(lie)不(bu)(bu)銹(xiu)鋼(gang)(gang)(gang)(gang)的(de)高(gao)加工(gong)(gong)性能鋼(gang)(gang)(gang)(gang)種時,可以(yi)進行一定(ding)程度的(de)深(shen)拉深(shen)加工(gong)(gong)。奧氏體系(xi)列(lie)(lie)不(bu)(bu)銹(xiu)鋼(gang)(gang)(gang)(gang)的(de)代表型鋼(gang)(gang)(gang)(gang)種 SUS 304(18Cr -18Ni),因(yin)為它(ta)的(de)LDR為2.5,可以(yi)進行相對(dui)較大(da)的(de)深(shen)拉深(shen)加工(gong)(gong)。
但(dan)由于加(jia)工硬(ying)化傾向大而急劇地(di)增加(jia)了(le)加(jia)工難度,有時(shi)竟發(fa)生裂紋或斷(duan)裂。為此,沖壓廠(chang)家就在中間(jian)加(jia)上一(yi)道熱處理工序之后再進(jin)行深(shen)拉深(shen)加(jia)工。還必須注意,奧(ao)(ao)氏體系(xi)列不銹鋼的奧(ao)(ao)氏體穩(wen)定(ding)度低(di)的鋼種經過(guo)拉深(shen)后,有可能發(fa)生時(shi)效斷(duan)裂現象。

近年來,新潟縣(xian)燕(yan)市的(de)沖壓加(jia)工(gong)(gong)(gong)廠和新鴻縣(xian)工(gong)(gong)(gong)業技術(shu)(shu)中(zhong)心共(gong)同開發不銹鋼(gang)熱(re)(re)(re)沖壓技術(shu)(shu),實現了超深拉深加(jia)工(gong)(gong)(gong)。熱(re)(re)(re)沖壓技術(shu)(shu)就(jiu)是(shi)將凹模(mo)或者凸(tu)模(mo)其中(zhong)之一進行加(jia)熱(re)(re)(re),這樣不銹鋼(gang)原來的(de)拉深程度就(jiu)可以提高1.5~2.0倍。熱(re)(re)(re)沖壓加(jia)工(gong)(gong)(gong)設備的(de)工(gong)(gong)(gong)作原理(li)如(ru)圖(tu)6-9所(suo)示(shi)。其加(jia)工(gong)(gong)(gong)特性如(ru)圖(tu)6-10所(suo)示(shi)。
2. 彎曲與連續沖(chong)裁(cai)
奧(ao)氏(shi)體(ti)(ti)系列不(bu)(bu)銹(xiu)鋼進行彎(wan)(wan)曲(qu)(qu)加(jia)(jia)(jia)(jia)(jia)工(gong)是(shi)件簡(jian)單(dan)之事,可(ke)以(yi)(yi)制(zhi)作角鋼、槽鋼等(deng)(deng)(deng)型材使用(yong)。鐵素體(ti)(ti)系列,馬氏(shi)體(ti)(ti)系列不(bu)(bu)銹(xiu)鋼作為(wei)(wei)(wei)(wei)型材加(jia)(jia)(jia)(jia)(jia)工(gong),一(yi)般情況下(xia)沒(mei)有問題,但當彎(wan)(wan)曲(qu)(qu)半徑(jing)R小的(de)(de)(de)時(shi)候(hou),在(zai)折彎(wan)(wan)處有時(shi)會發(fa)生(sheng)斷(duan)(duan)裂(lie)。在(zai)JIS標(biao)準中(zhong)(zhong),對鐵素體(ti)(ti)、馬氏(shi)體(ti)(ti)系列的(de)(de)(de)不(bu)(bu)銹(xiu)鋼彎(wan)(wan)曲(qu)(qu)試驗標(biao)準規定(ding),彎(wan)(wan)曲(qu)(qu)半徑(jing)R為(wei)(wei)(wei)(wei)1.0t(t為(wei)(wei)(wei)(wei)板材厚(hou)度)不(bu)(bu)應發(fa)生(sheng)彎(wan)(wan)曲(qu)(qu)斷(duan)(duan)裂(lie)。還有,必須注意不(bu)(bu)銹(xiu)鋼彎(wan)(wan)曲(qu)(qu)加(jia)(jia)(jia)(jia)(jia)工(gong)回彈量大的(de)(de)(de)特點。落(luo)料(liao)(liao)(liao)(俗稱下(xia)料(liao)(liao)(liao))或(huo)稱為(wei)(wei)(wei)(wei)沖(chong)(chong)(chong)(chong)裁加(jia)(jia)(jia)(jia)(jia)工(gong),大多數(shu)是(shi)采用(yong)沖(chong)(chong)(chong)(chong)床連續加(jia)(jia)(jia)(jia)(jia)工(gong)的(de)(de)(de)方式,有時(shi)在(zai)沖(chong)(chong)(chong)(chong)切斷(duan)(duan)面(mian)上,發(fa)生(sheng)塌邊現(xian)象(即(ji)沖(chong)(chong)(chong)(chong)切面(mian)與基準平面(mian)不(bu)(bu)垂直)。精密(mi)落(luo)料(liao)(liao)(liao)是(shi)從變壓(ya)器等(deng)(deng)(deng)使用(yong)疊層的(de)(de)(de)電磁鋼板的(de)(de)(de)加(jia)(jia)(jia)(jia)(jia)工(gong)技(ji)術(shu)(shu)開展起來(lai)的(de)(de)(de)技(ji)術(shu)(shu),對粒(li)子(zi)(zi)加(jia)(jia)(jia)(jia)(jia)速器的(de)(de)(de)套環(collar)或(huo)電子(zi)(zi)零部(bu)件中(zhong)(zhong)的(de)(de)(de)引線框(lead frame)等(deng)(deng)(deng)等(deng)(deng)(deng),從較厚(hou)的(de)(de)(de)板材到(dao)超薄材,精密(mi)落(luo)料(liao)(liao)(liao)得到(dao)廣泛(fan)應用(yong)。沖(chong)(chong)(chong)(chong)壓(ya)加(jia)(jia)(jia)(jia)(jia)工(gong)機(ji)(ji)械(xie)亦可(ke)以(yi)(yi)進行精密(mi)沖(chong)(chong)(chong)(chong)壓(ya)(落(luo)料(liao)(liao)(liao))加(jia)(jia)(jia)(jia)(jia)工(gong),但由于沖(chong)(chong)(chong)(chong)壓(ya)塌邊的(de)(de)(de)問題,一(yi)般不(bu)(bu)能作為(wei)(wei)(wei)(wei)成(cheng)品直接(jie)使用(yong)。在(zai)精密(mi)沖(chong)(chong)(chong)(chong)壓(ya)中(zhong)(zhong),為(wei)(wei)(wei)(wei)控制(zhi)塌邊,就需加(jia)(jia)(jia)(jia)(jia)一(yi)道機(ji)(ji)械(xie)控制(zhi)的(de)(de)(de)工(gong)藝措(cuo)施(shi),這需要(yao)按產(chan)品用(yong)途以(yi)(yi)及成(cheng)本兩(liang)方面(mian)來(lai)權衡。在(zai)加(jia)(jia)(jia)(jia)(jia)工(gong)方法(fa)競爭(zheng)上,還有一(yi)種“蝕刻”方法(fa),在(zai)電子(zi)(zi)產(chan)品的(de)(de)(de)接(jie)線框等(deng)(deng)(deng)超薄產(chan)品中(zhong)(zhong),在(zai)加(jia)(jia)(jia)(jia)(jia)工(gong)廠家的(de)(de)(de)技(ji)術(shu)(shu)競爭(zheng)中(zhong)(zhong),兩(liang)者幾乎各占(zhan)一(yi)半。
3. 加工油(you)、表面保(bao)護薄(bo)膜(mo)和其他潤滑
a. 表面保(bao)護薄膜-為(wei)(wei)了保(bao)持不銹鋼的匠藝性、防止產(chan)生瑕疵(ci)以及作為(wei)(wei)潤滑而敷(fu)于(yu)材料表面的聚(ju)(ju)氯乙烯或(huo)聚(ju)(ju)乙烯等薄膜。
b. 揮發性加(jia)工(gong)油(you)--加(jia)工(gong)時有潤(run)滑(hua)效果(guo)而后又能(neng)揮發掉的加(jia)工(gong)油(you)。使(shi)用完(wan)全揮發型的,可以省掉清洗工(gong)序。
c. 潤滑不銹(xiu)鋼(gang)板-具有透明(ming)石蠟涂(tu)裝(zhuang)的(de)不銹(xiu)鋼(gang),它比加工油或(huo)表面保護膜有更(geng)好的(de)加工性。
在(zai)沖床(chuang)上進行不(bu)銹鋼板(ban)彎(wan)曲、沖裁(落料)等加工(gong)時,可使用加工(gong)油、表(biao)(biao)(biao)面保(bao)護(hu)(hu)(hu)薄(bo)(bo)膜(mo)(mo)(mo)或直接使用潤滑鋼板(ban)。在(zai)表(biao)(biao)(biao)6-1中(zhong),對(dui)加工(gong)油、表(biao)(biao)(biao)面保(bao)護(hu)(hu)(hu)薄(bo)(bo)膜(mo)(mo)(mo)和(he)潤滑鋼板(ban)進行比較。表(biao)(biao)(biao)面保(bao)護(hu)(hu)(hu)薄(bo)(bo)膜(mo)(mo)(mo)是(shi)(shi)不(bu)銹鋼保(bao)持匠藝性(xing)的(de)(de)一項(xiang)重(zhong)要(yao)措施。所(suo)用樹脂為聚(ju)氯乙烯系列(lie)或聚(ju)乙烯系列(lie)。材(cai)料運轉自(zi)始至終都是(shi)(shi)用表(biao)(biao)(biao)面保(bao)護(hu)(hu)(hu)薄(bo)(bo)膜(mo)(mo)(mo)對(dui)材(cai)料表(biao)(biao)(biao)面施行保(bao)護(hu)(hu)(hu)。使用表(biao)(biao)(biao)面保(bao)護(hu)(hu)(hu)薄(bo)(bo)膜(mo)(mo)(mo),最(zui)容易發生的(de)(de)問題(ti)就(jiu)是(shi)(shi)殘留糊(hu)狀物,貼附后(hou)(hou)長期保(bao)存在(zai)倉庫內的(de)(de)或者是(shi)(shi)不(bu)具備耐候性(xing)能的(de)(de)薄(bo)(bo)膜(mo)(mo)(mo)放置在(zai)室(shi)外的(de)(de),則容易發生損壞。表(biao)(biao)(biao)面保(bao)護(hu)(hu)(hu)薄(bo)(bo)膜(mo)(mo)(mo)要(yao)根(gen)據用途(tu)和(he)加工(gong)方法選定。主要(yao)廠家生產(chan)的(de)(de)表(biao)(biao)(biao)面保(bao)護(hu)(hu)(hu)薄(bo)(bo)膜(mo)(mo)(mo)性(xing)能及其有(you)關事項(xiang)如表(biao)(biao)(biao)6-2所(suo)示。不(bu)使用表(biao)(biao)(biao)面保(bao)護(hu)(hu)(hu)薄(bo)(bo)膜(mo)(mo)(mo)時,一般情況(kuang)下要(yao)使用加工(gong)油。當使用加工(gong)油加工(gong)后(hou)(hou),需進行洗凈。洗凈的(de)(de)方法有(you)多種,最(zui)近在(zai)保(bao)護(hu)(hu)(hu)地球環(huan)境(jing)問題(ti)當中(zhong),規定了保(bao)護(hu)(hu)(hu)環(huan)境(jing)條例,對(dui)于破壞臭氧層的(de)(de)清洗劑做(zuo)出了限制。


因此(ci),當使用(yong)加(jia)工(gong)(gong)(gong)(gong)油(you)(you)(you)時,要考慮到洗(xi)凈和存放問題。在加(jia)工(gong)(gong)(gong)(gong)油(you)(you)(you)選定方面,從前認為(wei)由于(yu)不(bu)銹(xiu)鋼(gang)硬度(du)比普通鋼(gang)要高,加(jia)工(gong)(gong)(gong)(gong)不(bu)銹(xiu)鋼(gang)比普通鋼(gang)困難(nan),所以(yi)要選用(yong)有黏(nian)性(xing)的(de)(de)加(jia)工(gong)(gong)(gong)(gong)油(you)(you)(you)。具有黏(nian)性(xing)的(de)(de)加(jia)工(gong)(gong)(gong)(gong)油(you)(you)(you)往(wang)往(wang)是黏(nian)糊糊的(de)(de),在加(jia)工(gong)(gong)(gong)(gong)過程中不(bu)但(dan)變黑(hei)而且(qie)難(nan)以(yi)清(qing)洗(xi)。另外,其中多(duo)數情況(kuang)下加(jia)入氯系列(lie)添加(jia)劑。因此(ci),更有必要進行充分地(di)清(qing)洗(xi)。近年來,開發了許(xu)多(duo)水溶性(xing)加(jia)工(gong)(gong)(gong)(gong)油(you)(you)(you),在深拉(la)深等加(jia)工(gong)(gong)(gong)(gong)中,其潤滑性(xing)堪比原用(yong)油(you)(you)(you)性(xing)的(de)(de)加(jia)工(gong)(gong)(gong)(gong)油(you)(you)(you)。水溶性(xing)加(jia)工(gong)(gong)(gong)(gong)油(you)(you)(you)比較容易清(qing)洗(xi),應用(yong)效果很好。作為(wei)新(xin)技(ji)術,雖(sui)然加(jia)工(gong)(gong)(gong)(gong)條件受到某種程度(du)的(de)(de)限制,免(mian)清(qing)洗(xi)的(de)(de)揮發型加(jia)工(gong)(gong)(gong)(gong)油(you)(you)(you)仍得到推廣。
在揮(hui)發(fa)(fa)(fa)性加工(gong)油(you)中,有完全(quan)揮(hui)發(fa)(fa)(fa)型和部分(fen)殘留型等(deng)產(chan)品。需根據加工(gong)條件選擇,使用完全(quan)揮(hui)發(fa)(fa)(fa)型的可以(yi)省(sheng)掉加工(gong)后的清洗。在家電生產(chan)廠中,沖制(zhi)全(quan)自動洗衣(yi)機(ji)不銹鋼洗衣(yi)桶(tong)時就(jiu)是采用完全(quan)揮(hui)發(fa)(fa)(fa)型加工(gong)油(you)。在其他(ta)領域中,完全(quan)揮(hui)發(fa)(fa)(fa)型加工(gong)油(you)已實際運用到沖孔、內緣翻邊(bian)、壓(ya)制(zhi)筋板(ban)、彎曲和卷邊(bian)等(deng)沖壓(ya)工(gong)藝中。

由于使(shi)用揮(hui)發性(xing)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)油(you)(you)可(ke)以省掉清(qing)洗(xi)(xi)工(gong)(gong)(gong)(gong)(gong)(gong)序,在流水(shui)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)作(zuo)業線上使(shi)用,可(ke)以降(jiang)低成本。主(zhu)要生產(chan)廠家的(de)(de)揮(hui)發性(xing)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)油(you)(you)產(chan)品如(ru)表6-3所示。如(ru)將揮(hui)發性(xing)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)油(you)(you)的(de)(de)涂(tu)敷方式和加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)條件(jian)進(jin)(jin)行改進(jin)(jin)時(shi),即(ji)可(ke)以完全省掉清(qing)洗(xi)(xi)工(gong)(gong)(gong)(gong)(gong)(gong)作(zuo)。但是(shi),揮(hui)發性(xing)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)油(you)(you)涂(tu)敷方式、加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)條件(jian)及(ji)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)夾具的(de)(de)質量管理(li)(li)不(bu)善(shan)時(shi),由于加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)夾具的(de)(de)磨損等可(ke)能(neng)產(chan)生對(dui)不(bu)銹(xiu)鋼的(de)(de)鐵粉銹(xiu)蝕(shi)事故。關于鐵粉銹(xiu)蝕(shi)檢查(cha)方法,可(ke)參(can)照本書后部章(zhang)節(jie)中的(de)(de)“使(shi)用時(shi)注意重占(zhan)日惠執處理(li)(li)”由的(de)(de)說明。
先前在(zai)沖壓(ya)加工過程(cheng)中使(shi)用(yong)加工油。為了(le)洗(xi)凈這些加工油而使(shi)用(yong)了(le)破壞臭(chou)氧層的(de)(de)三氯(lv)乙(yi)烷(wan),三氯(lv)乙(yi)烯等。后來,洗(xi)凈方法(fa)改為堿性(xing)洗(xi)凈方法(fa)。在(zai)1995年,考(kao)慮到保護(hu)地球環境(jing)問題,開發了(le)潤滑不(bu)銹(xiu)鋼板。在(zai)汽車、電機、燃氣器具領域中,積極推(tui)廣了(le)省掉清洗(xi)工序的(de)(de)潤滑不(bu)銹(xiu)鋼板。特(te)別是在(zai)汽車領域中的(de)(de)排氣分支管的(de)(de)不(bu)銹(xiu)鋼化過程(cheng)中,實踐證明,加工這種(zhong)形(xing)狀(zhuang)復雜(za)的(de)(de)工件,認為潤滑不(bu)銹(xiu)鋼板比以前使(shi)用(yong)潤滑油的(de)(de)加工性(xing)更(geng)優越(yue)。所(suo)以,潤滑不(bu)銹(xiu)鋼板的(de)(de)需要量大幅度增加。

潤(run)滑(hua)不(bu)銹(xiu)鋼板,根據用(yong)途亦有不(bu)涂薄膜的。非脫膜型(xing)和脫膜型(xing)兩類(lei)已經產品化了(le)。潤(run)滑(hua)不(bu)銹(xiu)鋼板種類(lei)和特性如表(biao)6-4所示。在(zai)建(jian)筑材料(liao)領域中,使用(yong)潤(run)滑(hua)不(bu)銹(xiu)鋼板做屋頂時,非脫膜型(xing)和脫膜型(xing)一樣(yang),其(qi)薄膜經過1~2年的紫外線照射就消失了(le)。作為工(gong)(gong)程實(shi)例,用(yong)于西(xi)武百貨大樓和福(fu)岡機(ji)場(chang)候機(ji)大廳(ting)。實(shi)踐證明,潤(run)滑(hua)不(bu)銹(xiu)鋼板的加(jia)工(gong)(gong)性比加(jia)工(gong)(gong)油還要優越(yue),見(jian)表(biao)6-5。
不(bu)(bu)銹鋼(gang)板生產廠家(jia)的潤滑(hua)不(bu)(bu)銹鋼(gang)板產品,在透明(ming)涂裝不(bu)(bu)銹鋼(gang)項目(mu)中有介(jie)紹。

