一、數控銑床刀具種類
數(shu)控(kong)(kong)(kong)加(jia)(jia)(jia)工中(zhong)刀具(ju)的(de)(de)選(xuan)擇和切(qie)削用(yong)量(liang)(liang)(liang)確(que)(que)定是在(zai)人機交互(hu)狀態下完成,要求(qiu)編(bian)程人員必須掌握刀具(ju)選(xuan)擇和切(qie)削用(yong)量(liang)(liang)(liang)確(que)(que)定的(de)(de)基(ji)本原則,在(zai)編(bian)程時充(chong)分考(kao)慮數(shu)控(kong)(kong)(kong)加(jia)(jia)(jia)工特點(dian)(dian),正(zheng)確(que)(que)選(xuan)擇刀刃具(ju)及切(qie)削用(yong)量(liang)(liang)(liang)。數(shu)控(kong)(kong)(kong)加(jia)(jia)(jia)工技術(shu)涉及的(de)(de)范圍很廣,就應用(yong)方面而言(yan),其加(jia)(jia)(jia)工技術(shu)的(de)(de)特點(dian)(dian)和難(nan)點(dian)(dian)仍在(zai)于(yu)如(ru)何高(gao)速、高(gao)效率(lv)地正(zheng)確(que)(que)選(xuan)用(yong)數(shu)控(kong)(kong)(kong)機床刀具(ju)編(bian)制(zhi)出(chu)符合(he)產(chan)品(pin)技術(shu)要求(qiu)的(de)(de)數(shu)控(kong)(kong)(kong)加(jia)(jia)(jia)工工藝(yi)及程序。數(shu)控(kong)(kong)(kong)加(jia)(jia)(jia)工可以大幅度縮短(duan)產(chan)品(pin)的(de)(de)制(zhi)造(zao)周期,有效的(de)(de)解決機械產(chan)品(pin)中(zhong)復雜、精密、單件(jian)小批量(liang)(liang)(liang)、形狀多變的(de)(de)零(ling)件(jian)加(jia)(jia)(jia)工。
數控銑床加(jia)工(gong)刀(dao)具(ju)種(zhong)類很多,為(wei)(wei)了(le)適應(ying)數控機床(chuang)高(gao)(gao)速、高(gao)(gao)效(xiao)和自動化(hua)程(cheng)度高(gao)(gao)的(de)特點,所用刀(dao)具(ju)正(zheng)朝著標準化(hua)、通(tong)用化(hua)和模塊化(hua)的(de)方向發展,主要(yao)分為(wei)(wei)銑削刀(dao)具(ju)和孔加(jia)工(gong)刀(dao)具(ju)兩大類。為(wei)(wei)了(le)滿足高(gao)(gao)效(xiao)和特殊的(de)銑削要(yao)求,又(you)發展了(le)各種(zhong)特殊用途的(de)專(zhuan)用刀(dao)具(ju)。
(1)刀柄結構形式
數(shu)控(kong)銑床刀(dao)(dao)(dao)具刀(dao)(dao)(dao)柄的結構(gou)形式(shi)分為模(mo)塊(kuai)式(shi)與整體式(shi)兩種(zhong)。模(mo)塊(kuai)式(shi)刀(dao)(dao)(dao)具系(xi)統(tong)是一種(zhong)較先進的刀(dao)(dao)(dao)具系(xi)統(tong),其(qi)每把刀(dao)(dao)(dao)柄都可通過(guo)各(ge)種(zhong)系(xi)列化(hua)的模(mo)塊(kuai)組裝而成。針對不同(tong)(tong)的加工零件(jian)和(he)機床,采取不同(tong)(tong)的組裝方案(an),可獲得多種(zhong)刀(dao)(dao)(dao)柄系(xi)列,從(cong)而提(ti)高(gao)刀(dao)(dao)(dao)柄的適應能(neng)力和(he)利用(yong)率。
整體式刀(dao)柄(bing)裝夾(jia)刀(dao)具的工(gong)作部分與(yu)機(ji)床上安裝定位用的柄(bing)部是一體的。這種(zhong)刀(dao)柄(bing)對機(ji)床與(yu)零件的變換(huan)適(shi)應能力較差。為(wei)適(shi)應零件與(yu)機(ji)床的變換(huan),用戶必須(xu)儲備各種(zhong)規格的刀(dao)柄(bing),因(yin)此刀(dao)柄(bing)的利用率較低。
數控銑床刀柄(bing)(bing)與(yu)(yu)主(zhu)(zhu)軸孔的配合錐(zhui)面(mian)采(cai)(cai)(cai)用(yong)(yong)7:24圓錐(zhui)柄(bing)(bing),并采(cai)(cai)(cai)用(yong)(yong)相應(ying)(ying)(ying)型式的拉(la)釘,與(yu)(yu)機(ji)床主(zhu)(zhu)軸相結合。錐(zhui)柄(bing)(bing)具有(you)不自鎖(suo),換刀方(fang)便等特(te)點。刀柄(bing)(bing)常(chang)用(yong)(yong)的規(gui)格有(you)40號(hao)(hao)、45號(hao)(hao)和50號(hao)(hao)。目(mu)前在(zai)我國應(ying)(ying)(ying)用(yong)(yong)較(jiao)為(wei)廣泛的有(you)IS07388—1983.MAS403—1982.ANSI/ASME 135.50—1985等,選擇時(shi)應(ying)(ying)(ying)考慮刀柄(bing)(bing)規(gui)格與(yu)(yu)機(ji)床主(zhu)(zhu)軸、機(ji)械手(shou)相適(shi)應(ying)(ying)(ying)。JT:表示采(cai)(cai)(cai)用(yong)(yong)國際標(biao)準IS07388號(hao)(hao)加(jia)工(gong)中(zhong)(zhong)心機(ji)床用(yong)(yong)錐(zhui)柄(bing)(bing)柄(bing)(bing)部(bu)(帶(dai)機(ji)械手(shou)夾持槽);其(qi)(qi)后數字為(wei)相應(ying)(ying)(ying)的ISO錐(zhui)度號(hao)(hao)。BT:表示采(cai)(cai)(cai)用(yong)(yong)日(ri)本標(biao)準MAS403號(hao)(hao)加(jia)工(gong)中(zhong)(zhong)心機(ji)床用(yong)(yong)錐(zhui)柄(bing)(bing)柄(bing)(bing)部(bu)(帶(dai)機(ji)械手(shou)夾持槽);其(qi)(qi)后數字為(wei)相應(ying)(ying)(ying)的ISO錐(zhui)度號(hao)(hao)。對于(yu)高速(su)切(qie)削(xue)一(yi)般采(cai)(cai)(cai)用(yong)(yong)HSK系列刀柄(bing)(bing)。
為(wei)提高(gao)加(jia)(jia)工效率,應盡可能選用(yong)(yong)高(gao)效率的刀具(ju)和(he)刀柄(bing)。選用(yong)(yong)強(qiang)力(li)(li)銑(xian)夾(jia)(jia)(jia)頭(tou)刀柄(bing),夾(jia)(jia)(jia)持(chi)精度高(gao),可以用(yong)(yong)來夾(jia)(jia)(jia)持(chi)直柄(bing)刀具(ju),因卡(ka)簧(huang)自身夾(jia)(jia)(jia)緊變形小(xiao)自鎖性好,夾(jia)(jia)(jia)緊力(li)(li)大,可以用(yong)(yong)于強(qiang)力(li)(li)銑(xian)削(xue)加(jia)(jia)工;還(huan)可以用(yong)(yong)于高(gao)精度銑(xian)鉸孔加(jia)(jia)工,也可通過接桿夾(jia)(jia)(jia)持(chi)帶孔類刀具(ju)。
選用(yong)彈(dan)簧卡頭(tou)刀(dao)(dao)(dao)柄,卡簧彈(dan)性(xing)變形(xing)量(liang)為1mm,主要(yao)夾(jia)持小規格銑(xian)刀(dao)(dao)(dao),如鉆(zhan)頭(tou)、銑(xian)刀(dao)(dao)(dao)、鉸刀(dao)(dao)(dao)、絲錐等(deng)。選用(yong)模塊式(shi)工(gong)(gong)(gong)具系統由(you)于(yu)其(qi)定位精度高(gao),裝卸方便(bian),連接剛性(xing)好,具有(you)良好的抗(kang)振性(xing),是(shi)目前用(yong)得較多的一種型式(shi),它由(you)刀(dao)(dao)(dao)柄、中間接桿以(yi)及(ji)工(gong)(gong)(gong)作頭(tou)組成(cheng)(cheng)。選用(yong)粗鏜(tang)孔可(ke)選用(yong)雙刃鏜(tang)刀(dao)(dao)(dao)刀(dao)(dao)(dao)柄,既可(ke)提(ti)(ti)高(gao)加(jia)工(gong)(gong)(gong)效(xiao)率(lv),又有(you)利于(yu)減(jian)少切(qie)削(xue)振動;對(dui)于(yu)批量(liang)大、加(jia)工(gong)(gong)(gong)復(fu)(fu)雜的典型工(gong)(gong)(gong)件,應(ying)盡可(ke)能(neng)選用(yong)復(fu)(fu)合(he)刀(dao)(dao)(dao)具。盡管復(fu)(fu)合(he)刀(dao)(dao)(dao)具與(yu)刀(dao)(dao)(dao)柄價格較為昂貴(gui),但(dan)在數(shu)控機床上采用(yong)復(fu)(fu)合(he)刀(dao)(dao)(dao)具加(jia)工(gong)(gong)(gong),可(ke)以(yi)使工(gong)(gong)(gong)序(xu)集(ji)中,把(ba)多道(dao)工(gong)(gong)(gong)序(xu)合(he)并成(cheng)(cheng)一道(dao)工(gong)(gong)(gong)序(xu)、由(you)一把(ba)刀(dao)(dao)(dao)具完(wan)成(cheng)(cheng),有(you)利于(yu)減(jian)少加(jia)工(gong)(gong)(gong)時間和換刀(dao)(dao)(dao)次數(shu),顯著(zhu)提(ti)(ti)高(gao)生產(chan)效(xiao)率(lv)。
(2)數控銑床刀具的分類
數控銑(xian)床刀(dao)具(ju)的分(fen)類(lei)有多種方法,根(gen)據刀(dao)具(ju)結構可(ke)(ke)分(fen)為(wei):①整體式(shi)(shi)②鑲嵌式(shi)(shi),采用焊(han)接或機(ji)夾式(shi)(shi)連(lian)接,機(ji)夾式(shi)(shi)又可(ke)(ke)分(fen)為(wei)可(ke)(ke)轉位(wei)和不可(ke)(ke)轉位(wei)兩(liang)種③特殊(shu)型式(shi)(shi),如復合式(shi)(shi)刀(dao)具(ju),減震(zhen)式(shi)(shi)刀(dao)具(ju)等(deng)。
根據制造刀具所用的材料可分為:①高速鋼刀具②硬質合金刀具:硬質合金根據國際標準ISO分類,把所有牌號分成用顏色標識的六大類,分別以字母P、M、K、N、S、H表示。P類用于加工長切屑的鋼件;M類用于加工不銹鋼件;K類用于加工短切屑的鑄鐵件;N類用于加工短切屑的非鐵材料;s類用于加工難加工材料H類用于加工硬材料。鍍層硬質合金刀具又分為:化學氣相沉積CVD和物理氣相沉積PVD兩種。③金剛(gang)石刀(dao)具(ju)④陶瓷刀(dao)片材(cai)料如(ru)氮(dan)化硅陶瓷Si3N4,立方氮(dan)化硼CBN。
從切削工(gong)藝上可分(fen)為:銑削類刀(dao)(dao)具(ju)(面銑刀(dao)(dao)、立銑刀(dao)(dao)、圓(yuan)鼻刀(dao)(dao)、球頭(tou)銑刀(dao)(dao)、錐(zhui)度銑刀(dao)(dao))、孔加工(gong)類刀(dao)(dao)具(ju)(麻(ma)花鉆、鉸刀(dao)(dao)、鏜刀(dao)(dao)、絲錐(zhui)等)。
為了滿足數控機床對刀具耐用、易調、穩定、可換等要求,機夾式可轉位刀具得到廣泛的應用,占整個數控刀具的40%-50%,金屬切除(chu)量占總數的80%~90%。
二、數控加工刀具的選擇
刀具選擇的(de)總原則:安(an)裝調(diao)整方便、可(ke)靠性(xing)好、剛(gang)性(xing)好、耐(nai)用(yong)度和精(jing)度高(gao)。在滿足加工(gong)要求的(de)前提下(xia),盡量選擇刀柄較短(duan)的(de)刀具,以增強(qiang)加工(gong)的(de)剛(gang)性(xing)。
(1)根據工件的表面尺寸選擇刀具
選(xuan)取(qu)刀(dao)(dao)(dao)(dao)(dao)具時(shi)(shi),要使刀(dao)(dao)(dao)(dao)(dao)具的(de)(de)尺(chi)寸(cun)與被(bei)加工(gong)件(jian)的(de)(de)表面(mian)(mian)尺(chi)寸(cun)相(xiang)適應用(yong)。生產中(zhong),加工(gong)平(ping)(ping)面(mian)(mian)零件(jian)周邊的(de)(de)輪廓,常采(cai)用(yong)立銑刀(dao)(dao)(dao)(dao)(dao);銑削平(ping)(ping)面(mian)(mian),應選(xuan)硬質(zhi)合金刀(dao)(dao)(dao)(dao)(dao)片銑刀(dao)(dao)(dao)(dao)(dao)。加工(gong)凸臺、凹槽時(shi)(shi),選(xuan)高速(su)鋼立銑刀(dao)(dao)(dao)(dao)(dao);加工(gong)毛(mao)坯(pi)表面(mian)(mian)或(huo)孔粗加工(gong)時(shi)(shi),可選(xuan)用(yong)鑲(xiang)硬質(zhi)合金刀(dao)(dao)(dao)(dao)(dao)片的(de)(de)玉米(mi)銑刀(dao)(dao)(dao)(dao)(dao);對一些立體型面(mian)(mian)和變(bian)斜面(mian)(mian)輪廓外形的(de)(de)加工(gong),選(xuan)用(yong)盤形銑刀(dao)(dao)(dao)(dao)(dao)、圓鼻刀(dao)(dao)(dao)(dao)(dao)、平(ping)(ping)刀(dao)(dao)(dao)(dao)(dao)做粗加工(gong),選(xuan)用(yong)球頭銑刀(dao)(dao)(dao)(dao)(dao)、環形銑刀(dao)(dao)(dao)(dao)(dao)、錐形銑刀(dao)(dao)(dao)(dao)(dao)做精加工(gong)。
(2)根據工件的表面形狀選擇刀具
在進行模具(ju)(ju)加工時,由于(yu)球(qiu)(qiu)(qiu)頭刀(dao)具(ju)(ju)的(de)端(duan)部切削速(su)度(du)為零,因(yin)此(ci)(ci),為保證加工精(jing)(jing)度(du),切削行距一般(ban)采用(yong)頂(ding)端(duan)密距,故(gu)球(qiu)(qiu)(qiu)頭銑刀(dao)常(chang)用(yong)于(yu)曲(qu)面(mian)(mian)的(de)精(jing)(jing)加工。而平(ping)(ping)頭刀(dao)具(ju)(ju)在表面(mian)(mian)加工質量和(he)切削效率(lv)方(fang)面(mian)(mian)都優(you)于(yu)球(qiu)(qiu)(qiu)頭刀(dao),因(yin)此(ci)(ci),只要在保證不過切的(de)前提(ti)下,無論(lun)是曲(qu)面(mian)(mian)的(de)粗加工還是精(jing)(jing)加工,都應優(you)先選擇平(ping)(ping)頭刀(dao)。另(ling)外,刀(dao)具(ju)(ju)的(de)耐用(yong)度(du)和(he)精(jing)(jing)度(du)與(yu)刀(dao)具(ju)(ju)價格(ge)關系(xi)極(ji)大,必須(xu)引起注意的(de)是,在大多數情況(kuang)下,選擇好的(de)刀(dao)具(ju)(ju)雖然增加了刀(dao)具(ju)(ju)成本,但由此(ci)(ci)帶(dai)來的(de)加工質量和(he)加工效率(lv)的(de)提(ti)高,則可以(yi)使整個加工成本大大降低(di)。
(3)合理安排刀具的排列順序
在經濟(ji)型(xing)數(shu)控(kong)機床的(de)加(jia)工(gong)(gong)過程(cheng)中,由(you)于刀(dao)(dao)(dao)具(ju)的(de)磨(mo)損、測(ce)量(liang)和更換(huan)多為人工(gong)(gong)手動進行,占(zhan)用(yong)(yong)輔助時間較長(chang),因此,必須合理(li)安排(pai)刀(dao)(dao)(dao)具(ju)的(de)排(pai)列順序。一(yi)般應遵循以下原(yuan)則:①工(gong)(gong)序集中一(yi)次裝(zhuang)夾(jia),同一(yi)把(ba)刀(dao)(dao)(dao)具(ju)能完成(cheng)其進行的(de)所(suo)有(you)加(jia)工(gong)(gong)步驟;②粗精(jing)加(jia)工(gong)(gong)的(de)刀(dao)(dao)(dao)具(ju)應分開使用(yong)(yong);③先面后(hou)孔;④先進行曲面精(jing)加(jia)工(gong)(gong),后(hou)進行二(er)維輪(lun)廓精(jing)加(jia)工(gong)(gong);⑤合理(li)利用(yong)(yong)數(shu)控(kong)機床的(de)自動換(huan)刀(dao)(dao)(dao)功能,以提高生產效率;⑥盡量(liang)減少刀(dao)(dao)(dao)具(ju)數(shu)量(liang)。