模具(ju)制造精(jing)加(jia)工工序，你知道多少？

　　具(ju)零(ling)件(jian)的(de)加工(gong)，根據零(ling)件(jian)的(de)外觀形狀不同(tong)，大(da)致可把零(ling)件(jian)分三類(lei)(lei)：板類(lei)(lei)、異形零(ling)件(jian)及(ji)軸類(lei)(lei)，其共同(tong)的(de)工(gong)藝(yi)過程大(da)致為：粗加工(gong)——熱處(chu)理(淬火、調質(zhi))——精磨——電加工(gong)——鉗工(gong)(表面處(chu)理)——組配加工(gong)。

　　1、零件熱處理

　　零(ling)件(jian)的(de)(de)熱(re)處(chu)(chu)理工序，在使零(ling)件(jian)獲得要求(qiu)的(de)(de)硬度的(de)(de)同(tong)時(shi)，還需(xu)對(dui)內應力(li)進(jin)行控制(zhi)，保證零(ling)件(jian)加工時(shi)尺寸(cun)的(de)(de)穩定性，不同(tong)的(de)(de)材(cai)(cai)(cai)質分(fen)別(bie)有不同(tong)的(de)(de)處(chu)(chu)理方式。隨著(zhu)近年來(lai)模(mo)(mo)具工業(ye)的(de)(de)發展，使用的(de)(de)材(cai)(cai)(cai)料(liao)(liao)種類(lei)(lei)增多了(le)，除了(le)Cr12、40Cr、Cr12MoV、硬質合(he)金外，對(dui)一些工作強(qiang)度大，受力(li)苛刻的(de)(de)凸(tu)、凹模(mo)(mo)，可選用新材(cai)(cai)(cai)料(liao)(liao)粉末合(he)金鋼，如V10、ASP23等，此類(lei)(lei)材(cai)(cai)(cai)質具有較高的(de)(de)熱(re)穩定性和(he)良好的(de)(de)組(zu)織(zhi)狀態。

　　針對(dui)(dui)以(yi)Cr12MoV為材質的零件(jian)(jian)，在(zai)粗加(jia)工后(hou)進(jin)行淬火(huo)(huo)(huo)處(chu)理，淬火(huo)(huo)(huo)后(hou)工件(jian)(jian)存(cun)在(zai)很大的存(cun)留應(ying)力，容(rong)易導(dao)致精(jing)加(jia)工或工作中開裂，零件(jian)(jian)淬火(huo)(huo)(huo)后(hou)應(ying)趁熱回(hui)火(huo)(huo)(huo)，消除(chu)淬火(huo)(huo)(huo)應(ying)力。淬火(huo)(huo)(huo)溫度控制在(zai)900-1020℃，然(ran)后(hou)冷卻(que)至200-220℃出(chu)爐空冷，隨后(hou)迅速回(hui)爐220℃回(hui)火(huo)(huo)(huo)，這種方法(fa)稱為一次硬化(hua)工藝，可以(yi)獲得較(jiao)高的強度及耐(nai)磨(mo)性，對(dui)(dui)于以(yi)磨(mo)損為主(zhu)要失效(xiao)形式(shi)的模具效(xiao)果較(jiao)好。生(sheng)產中遇(yu)到一些(xie)拐角(jiao)較(jiao)多(duo)、形狀復雜(za)的工件(jian)(jian)，回(hui)火(huo)(huo)(huo)還不足以(yi)消除(chu)淬火(huo)(huo)(huo)應(ying)力，精(jing)加(jia)工前(qian)還需進(jin)行去應(ying)力退火(huo)(huo)(huo)或多(duo)次時效(xiao)處(chu)理，充分釋放應(ying)力。

　　針對(dui)V10、APS23等粉末(mo)合金(jin)鋼零(ling)件，因(yin)其(qi)(qi)能承受高溫(wen)回火(huo)，淬(cui)火(huo)時可采(cai)用(yong)(yong)二次硬化工藝，1050-1080℃淬(cui)火(huo)，再用(yong)(yong)490-520℃高溫(wen)回火(huo)并(bing)進(jin)行多次，可以獲得較高的(de)沖擊韌性及穩定(ding)性，對(dui)以崩刃為主(zhu)要(yao)失效形(xing)式的(de)模具很適用(yong)(yong)。粉末(mo)合金(jin)鋼的(de)造價較高，但其(qi)(qi)性能好，正(zheng)在形(xing)成一種廣泛運用(yong)(yong)趨勢。

　　2、零件的磨削(xue)加工

　　磨(mo)削(xue)(xue)加(jia)工(gong)(gong)采(cai)用的(de)機床(chuang)有(you)(you)三種主要(yao)類型(xing)：平面磨(mo)床(chuang)、內外圓(yuan)磨(mo)床(chuang)及工(gong)(gong)具磨(mo)具。精(jing)加(jia)工(gong)(gong)磨(mo)削(xue)(xue)時要(yao)嚴格控制(zhi)磨(mo)削(xue)(xue)變形(xing)和磨(mo)削(xue)(xue)裂紋的(de)產(chan)生，即(ji)使是十分微小(xiao)(xiao)的(de)裂紋，在后續的(de)加(jia)工(gong)(gong)使用中也(ye)會顯露(lu)出來。因(yin)此(ci)，精(jing)磨(mo)的(de)進刀要(yao)小(xiao)(xiao)，不能大，冷卻液(ye)要(yao)充分，尺寸公差在0.01mm以(yi)內的(de)零件(jian)要(yao)盡量(liang)恒(heng)溫(wen)磨(mo)削(xue)(xue)。由(you)計算(suan)可(ke)知，300mm長的(de)鋼件(jian)，溫(wen)差3℃時，材料有(you)(you)10.8μm左右的(de)變化，10.8=1.2×3×3(每(mei)100mm變形(xing)量(liang)1.2μm/℃)，各(ge)精(jing)加(jia)工(gong)(gong)工(gong)(gong)序(xu)都(dou)需充分考慮這一因(yin)素的(de)影響。

　　精磨(mo)時選擇好(hao)(hao)(hao)恰當的(de)(de)磨(mo)削(xue)砂(sha)輪(lun)(lun)(lun)(lun)(lun)十(shi)分(fen)(fen)重(zhong)要，針對模具鋼材的(de)(de)高(gao)釩高(gao)鉬(mu)狀況，選用(yong)GD單晶剛(gang)玉砂(sha)輪(lun)(lun)(lun)(lun)(lun)比較適用(yong)，當加(jia)(jia)工(gong)(gong)(gong)硬質合金、淬火(huo)硬度高(gao)的(de)(de)材質時，優先采用(yong)有機粘(zhan)結劑的(de)(de)金剛(gang)石砂(sha)輪(lun)(lun)(lun)(lun)(lun)，有機粘(zhan)結劑砂(sha)輪(lun)(lun)(lun)(lun)(lun)自磨(mo)利(li)性好(hao)(hao)(hao)，磨(mo)出(chu)(chu)的(de)(de)工(gong)(gong)(gong)件粗糙(cao)可達Ra=0.2μm，近年來，隨著新(xin)材料(liao)的(de)(de)應用(yong)，CBN砂(sha)輪(lun)(lun)(lun)(lun)(lun)，也即立方氮化(hua)硼砂(sha)輪(lun)(lun)(lun)(lun)(lun)顯示(shi)出(chu)(chu)十(shi)分(fen)(fen)好(hao)(hao)(hao)的(de)(de)加(jia)(jia)工(gong)(gong)(gong)效果，在數控成型磨(mo)，坐(zuo)標磨(mo)床(chuang)，CNC內外(wai)圓磨(mo)床(chuang)上(shang)精加(jia)(jia)工(gong)(gong)(gong)，效果優于其它種類砂(sha)輪(lun)(lun)(lun)(lun)(lun)。磨(mo)削(xue)加(jia)(jia)工(gong)(gong)(gong)中，要注意(yi)及(ji)時修整砂(sha)輪(lun)(lun)(lun)(lun)(lun)，保持(chi)砂(sha)輪(lun)(lun)(lun)(lun)(lun)的(de)(de)銳利(li)，當砂(sha)輪(lun)(lun)(lun)(lun)(lun)鈍化(hua)后(hou)，會在工(gong)(gong)(gong)件表面滑擦、擠壓，造成工(gong)(gong)(gong)件表面燒(shao)傷，強度降低。

　　板類零件(jian)的(de)加(jia)(jia)工(gong)(gong)大部分(fen)采用(yong)(yong)平面(mian)(mian)磨(mo)床加(jia)(jia)工(gong)(gong)，在(zai)(zai)加(jia)(jia)工(gong)(gong)中常會遇到(dao)(dao)一(yi)種(zhong)長而(er)薄的(de)薄板零件(jian)，此類零件(jian)的(de)加(jia)(jia)工(gong)(gong)較(jiao)難。因為加(jia)(jia)工(gong)(gong)時，在(zai)(zai)磁(ci)力的(de)吸(xi)附(fu)作用(yong)(yong)下(xia)(xia)，工(gong)(gong)件(jian)產(chan)生形(xing)變(bian)，緊貼(tie)于工(gong)(gong)作臺表面(mian)(mian)，當拿(na)下(xia)(xia)工(gong)(gong)件(jian)后，工(gong)(gong)件(jian)又會產(chan)生回復變(bian)形(xing)，厚(hou)度(du)測量一(yi)致，但平行度(du)達不到(dao)(dao)要(yao)求(qiu)，解(jie)決的(de)辦法可(ke)采用(yong)(yong)隔磁(ci)磨(mo)削(xue)(xue)法，磨(mo)削(xue)(xue)時以等高塊墊在(zai)(zai)工(gong)(gong)件(jian)下(xia)(xia)面(mian)(mian)，四面(mian)(mian)擋塊抵死，加(jia)(jia)工(gong)(gong)時小進刀，多光刀，加(jia)(jia)工(gong)(gong)好(hao)一(yi)面(mian)(mian)后，可(ke)不用(yong)(yong)再墊等高塊，直接吸(xi)附(fu)加(jia)(jia)工(gong)(gong)，這樣可(ke)改善磨(mo)削(xue)(xue)效(xiao)果，達到(dao)(dao)平行度(du)要(yao)求(qiu)。

　　軸類零件(jian)(jian)(jian)具有(you)回轉面，其(qi)加工(gong)(gong)(gong)(gong)廣泛采(cai)用內(nei)外圓磨(mo)(mo)(mo)床(chuang)及工(gong)(gong)(gong)(gong)具磨(mo)(mo)(mo)床(chuang)。加工(gong)(gong)(gong)(gong)過程中(zhong)，頭架(jia)及頂(ding)尖相當于(yu)母線(xian)，如果其(qi)存(cun)在(zai)(zai)跳動問題(ti)，加工(gong)(gong)(gong)(gong)出來的(de)工(gong)(gong)(gong)(gong)件(jian)(jian)(jian)同(tong)樣會(hui)產(chan)生此問題(ti)，影響零件(jian)(jian)(jian)的(de)質量，因此在(zai)(zai)加工(gong)(gong)(gong)(gong)前要(yao)做(zuo)好(hao)頭架(jia)及頂(ding)尖的(de)檢(jian)測工(gong)(gong)(gong)(gong)作。進行內(nei)孔磨(mo)(mo)(mo)削時，冷(leng)卻液(ye)要(yao)充分澆到磨(mo)(mo)(mo)削接觸位置，以利于(yu)磨(mo)(mo)(mo)削的(de)順利排出。加工(gong)(gong)(gong)(gong)薄壁軸類零件(jian)(jian)(jian)，最好(hao)采(cai)用夾(jia)持工(gong)(gong)(gong)(gong)藝臺，夾(jia)緊力不可過大，否則容(rong)易在(zai)(zai)工(gong)(gong)(gong)(gong)件(jian)(jian)(jian)圓周上產(chan)生“內(nei)三(san)角”變(bian)形。

　　3、電加(jia)工控制(zhi)

　　現代(dai)的模具工廠，不能缺少電(dian)加(jia)工，電(dian)加(jia)工可以對(dui)各類異形、高硬(ying)度零件進行加(jia)工，它分為線切割與電(dian)火花二(er)種。

　　慢走絲線(xian)切割(ge)加(jia)工(gong)(gong)精度(du)可(ke)達±0.003mm，粗糙度(du)Ra0.2μm。加(jia)工(gong)(gong)開始時(shi)(shi)，要先檢查機床(chuang)的狀況(kuang)，查看水(shui)的去(qu)離子度(du)，水(shui)溫，絲的垂(chui)直度(du)，張力(li)等各個因(yin)素，確保良(liang)好的加(jia)工(gong)(gong)狀態。線(xian)切割(ge)加(jia)工(gong)(gong)是在(zai)一(yi)整(zheng)塊材(cai)料上去(qu)除加(jia)工(gong)(gong)，它破壞了工(gong)(gong)件原有的應力(li)平(ping)衡，很容易(yi)引起應力(li)集中(zhong)(zhong)，特(te)別(bie)是在(zai)拐角處，因(yin)此(ci)當R＜0.2(特(te)別(bie)是尖角)時(shi)(shi)，應向設計部門提出(chu)改(gai)善建議(yi)。加(jia)工(gong)(gong)中(zhong)(zhong)處理應力(li)集中(zhong)(zhong)的方法，可(ke)運用矢量平(ping)移(yi)原理，精加(jia)工(gong)(gong)前先留(liu)余量1mm左(zuo)右，預加(jia)工(gong)(gong)出(chu)大致形狀，然后再進行(xing)熱處理，讓加(jia)工(gong)(gong)應力(li)在(zai)精加(jia)工(gong)(gong)前先行(xing)釋放(fang)，保證熱穩定性(xing)。

　　加(jia)(jia)工(gong)(gong)(gong)凸模時(shi)，絲的切(qie)入(ru)位置(zhi)及路徑的選(xuan)擇要仔(zi)細考慮。采用打孔(kong)穿絲加(jia)(jia)工(gong)(gong)(gong)，效果最佳。高精(jing)線切(qie)割加(jia)(jia)工(gong)(gong)(gong)，通常切(qie)割遍(bian)數為四次，可以保證零(ling)件質量。當加(jia)(jia)工(gong)(gong)(gong)帶有(you)錐度(du)的凹模時(shi)，本(ben)(ben)著快速高效的立場，第一遍(bian)粗加(jia)(jia)工(gong)(gong)(gong)直邊(bian)，第二(er)遍(bian)錐度(du)加(jia)(jia)工(gong)(gong)(gong)，接著再(zai)精(jing)加(jia)(jia)工(gong)(gong)(gong)直邊(bian)，這樣可不需進行X段(duan)垂直向精(jing)加(jia)(jia)工(gong)(gong)(gong)，只精(jing)加(jia)(jia)工(gong)(gong)(gong)刃口段(duan)直邊(bian)，既節(jie)約時(shi)間(jian)又節(jie)約成本(ben)(ben)。

　　電(dian)(dian)(dian)(dian)(dian)火花加(jia)(jia)工(gong)(gong)先要(yao)(yao)制(zhi)作電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)，電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)有粗、精之分。精加(jia)(jia)工(gong)(gong)電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)要(yao)(yao)求形狀符合(he)(he)性好(hao)(hao)，最好(hao)(hao)用CNC數控機(ji)床(chuang)加(jia)(jia)工(gong)(gong)完成。電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)的(de)材質(zhi)選擇上，紫銅(tong)電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)主要(yao)(yao)用于(yu)一(yi)般鋼件加(jia)(jia)工(gong)(gong)。Cu-W合(he)(he)金電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)，綜合(he)(he)性能好(hao)(hao)，特別(bie)是加(jia)(jia)工(gong)(gong)過(guo)程中(zhong)消耗量(liang)明顯比紫銅(tong)小(xiao)，配合(he)(he)足量(liang)的(de)沖刷液(ye)，很(hen)適合(he)(he)難加(jia)(jia)工(gong)(gong)材料加(jia)(jia)工(gong)(gong)及截面形狀復(fu)雜件精加(jia)(jia)工(gong)(gong)。制(zhi)作電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)時，需要(yao)(yao)計(ji)算電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)的(de)間(jian)隙量(liang)及電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)數量(liang)，當進(jin)(jin)行(xing)大(da)面積或重電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)加(jia)(jia)工(gong)(gong)時，工(gong)(gong)件和電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)裝(zhuang)夾要(yao)(yao)牢固，保證具有足夠的(de)強度，防止加(jia)(jia)工(gong)(gong)松動。進(jin)(jin)行(xing)深臺階加(jia)(jia)工(gong)(gong)時，對(dui)電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)各(ge)處(chu)的(de)損耗及因排(pai)液(ye)不暢引起的(de)電(dian)(dian)(dian)(dian)(dian)弧放電(dian)(dian)(dian)(dian)(dian)，要(yao)(yao)予以注意。

　　4、表面(mian)處理(li)及組配

　　零(ling)(ling)件(jian)(jian)表(biao)面在加工(gong)時(shi)留下刀痕(hen)、磨痕(hen)是(shi)應力(li)集中的地方，是(shi)裂(lie)紋(wen)擴展的源頭，因此在加工(gong)結束后，需(xu)要(yao)(yao)對零(ling)(ling)件(jian)(jian)進行(xing)表(biao)面強化(hua)(hua)(hua)，通過鉗(qian)工(gong)打磨，處理掉(diao)加工(gong)隱患(huan)。對工(gong)件(jian)(jian)的一些棱(leng)邊、銳角、孔口進行(xing)倒鈍，R化(hua)(hua)(hua)。一般地，電加工(gong)表(biao)面會產(chan)生6-10μm左右的變質硬化(hua)(hua)(hua)層，顏色(se)呈灰白色(se)，硬化(hua)(hua)(hua)層脆而且帶有殘留應力(li)，在使用(yong)之前(qian)要(yao)(yao)充(chong)分消除(chu)硬化(hua)(hua)(hua)層，方法為(wei)表(biao)面拋光(guang)，打磨去(qu)掉(diao)硬化(hua)(hua)(hua)層。

　　在磨削加(jia)(jia)工(gong)(gong)、電(dian)加(jia)(jia)工(gong)(gong)過程中，工(gong)(gong)件(jian)會有一定(ding)磁化(hua)，具有微弱磁力，十(shi)分容易吸(xi)著一些小東西，因此(ci)在組裝(zhuang)(zhuang)之前(qian)，要對(dui)工(gong)(gong)件(jian)作退磁處理，并用(yong)乙(yi)酸(suan)乙(yi)脂清洗表(biao)面。組裝(zhuang)(zhuang)過程中，先參看(kan)裝(zhuang)(zhuang)配(pei)(pei)(pei)圖(tu)，找(zhao)齊各零件(jian)，然(ran)后(hou)列出(chu)(chu)各零件(jian)相互之間的(de)(de)裝(zhuang)(zhuang)備順序，列出(chu)(chu)各項應(ying)注意事項，然(ran)后(hou)著手裝(zhuang)(zhuang)配(pei)(pei)(pei)模(mo)(mo)具，裝(zhuang)(zhuang)配(pei)(pei)(pei)一般先裝(zhuang)(zhuang)導柱導套，然(ran)后(hou)裝(zhuang)(zhuang)模(mo)(mo)架和凸凹模(mo)(mo)，然(ran)后(hou)再對(dui)各處間隙，特別是(shi)凸凹模(mo)(mo)間隙進行組配(pei)(pei)(pei)調整，裝(zhuang)(zhuang)配(pei)(pei)(pei)完成后(hou)要實(shi)施模(mo)(mo)具檢測，寫出(chu)(chu)整體情(qing)況(kuang)報(bao)告(gao)。對(dui)發(fa)現的(de)(de)問題，可采(cai)用(yong)逆(ni)向(xiang)思維(wei)法，即從后(hou)工(gong)(gong)序向(xiang)前(qian)工(gong)(gong)序，從精加(jia)(jia)工(gong)(gong)到(dao)粗加(jia)(jia)工(gong)(gong)，逐一檢查，直到(dao)找(zhao)出(chu)(chu)癥結，解決(jue)問題。

　　實踐證明，良好(hao)的(de)精(jing)加工(gong)過程控制，可(ke)以有效(xiao)減少零件超差、報廢(fei)，有效(xiao)提高模具的(de)一次(ci)成(cheng)功率及使用壽命。