一、數控銑床刀具種類
數(shu)(shu)控(kong)加(jia)(jia)(jia)工(gong)(gong)中刀(dao)(dao)具的選(xuan)擇(ze)和切削用量(liang)(liang)確(que)(que)定是在人機(ji)交互狀(zhuang)態下完(wan)成,要求(qiu)編程(cheng)(cheng)人員必(bi)須掌(zhang)握刀(dao)(dao)具選(xuan)擇(ze)和切削用量(liang)(liang)確(que)(que)定的基(ji)本(ben)原則,在編程(cheng)(cheng)時(shi)充分考慮數(shu)(shu)控(kong)加(jia)(jia)(jia)工(gong)(gong)特(te)點(dian),正(zheng)確(que)(que)選(xuan)擇(ze)刀(dao)(dao)刃具及切削用量(liang)(liang)。數(shu)(shu)控(kong)加(jia)(jia)(jia)工(gong)(gong)技術(shu)涉及的范圍很(hen)廣,就應用方(fang)面而言,其加(jia)(jia)(jia)工(gong)(gong)技術(shu)的特(te)點(dian)和難(nan)點(dian)仍在于如何(he)高速(su)、高效率地正(zheng)確(que)(que)選(xuan)用數(shu)(shu)控(kong)機(ji)床刀(dao)(dao)具編制(zhi)出符合產品(pin)技術(shu)要求(qiu)的數(shu)(shu)控(kong)加(jia)(jia)(jia)工(gong)(gong)工(gong)(gong)藝(yi)及程(cheng)(cheng)序。數(shu)(shu)控(kong)加(jia)(jia)(jia)工(gong)(gong)可以(yi)大幅(fu)度(du)縮短產品(pin)的制(zhi)造(zao)周期,有效的解決機(ji)械產品(pin)中復(fu)雜(za)、精密、單(dan)件小批量(liang)(liang)、形狀(zhuang)多變的零(ling)件加(jia)(jia)(jia)工(gong)(gong)。
數控銑床加工(gong)(gong)刀(dao)(dao)具(ju)種(zhong)類很(hen)多,為了適應數控機床高(gao)(gao)速、高(gao)(gao)效和自動化(hua)程度高(gao)(gao)的(de)(de)特點(dian),所用(yong)刀(dao)(dao)具(ju)正朝著標準化(hua)、通用(yong)化(hua)和模塊化(hua)的(de)(de)方向(xiang)發展(zhan),主要分為銑削刀(dao)(dao)具(ju)和孔(kong)加工(gong)(gong)刀(dao)(dao)具(ju)兩大類。為了滿足(zu)高(gao)(gao)效和特殊的(de)(de)銑削要求,又發展(zhan)了各種(zhong)特殊用(yong)途(tu)的(de)(de)專用(yong)刀(dao)(dao)具(ju)。
(1)刀柄結構形式
數控銑床(chuang)刀(dao)(dao)具(ju)刀(dao)(dao)柄的結構(gou)形式分為模(mo)(mo)塊(kuai)式與整體(ti)式兩種(zhong)。模(mo)(mo)塊(kuai)式刀(dao)(dao)具(ju)系(xi)統是一種(zhong)較先進的刀(dao)(dao)具(ju)系(xi)統,其每把(ba)刀(dao)(dao)柄都可通過(guo)各種(zhong)系(xi)列(lie)(lie)化的模(mo)(mo)塊(kuai)組裝而(er)成。針對不同(tong)的加工零件和(he)機床(chuang),采取不同(tong)的組裝方案,可獲得多種(zhong)刀(dao)(dao)柄系(xi)列(lie)(lie),從而(er)提高刀(dao)(dao)柄的適(shi)應能力和(he)利用(yong)率。
整(zheng)體式刀(dao)柄(bing)裝(zhuang)夾刀(dao)具(ju)的(de)(de)(de)工作部(bu)分與機床上安(an)裝(zhuang)定位用(yong)(yong)的(de)(de)(de)柄(bing)部(bu)是一體的(de)(de)(de)。這種(zhong)刀(dao)柄(bing)對機床與零件(jian)的(de)(de)(de)變換適應能力較差(cha)。為適應零件(jian)與機床的(de)(de)(de)變換,用(yong)(yong)戶必須儲備各種(zhong)規格的(de)(de)(de)刀(dao)柄(bing),因此刀(dao)柄(bing)的(de)(de)(de)利用(yong)(yong)率較低。
數控銑床刀(dao)(dao)柄(bing)(bing)與主(zhu)軸孔的(de)(de)(de)配合(he)錐(zhui)面(mian)采用(yong)(yong)(yong)(yong)7:24圓錐(zhui)柄(bing)(bing),并采用(yong)(yong)(yong)(yong)相(xiang)(xiang)(xiang)應(ying)型式的(de)(de)(de)拉釘,與機床(chuang)主(zhu)軸相(xiang)(xiang)(xiang)結(jie)合(he)。錐(zhui)柄(bing)(bing)具有(you)(you)不自鎖,換刀(dao)(dao)方(fang)便等特(te)點。刀(dao)(dao)柄(bing)(bing)常(chang)用(yong)(yong)(yong)(yong)的(de)(de)(de)規格有(you)(you)40號、45號和50號。目前在(zai)我國應(ying)用(yong)(yong)(yong)(yong)較為廣泛的(de)(de)(de)有(you)(you)IS07388—1983.MAS403—1982.ANSI/ASME 135.50—1985等,選(xuan)擇時應(ying)考慮刀(dao)(dao)柄(bing)(bing)規格與機床(chuang)主(zhu)軸、機械手(shou)相(xiang)(xiang)(xiang)適(shi)應(ying)。JT:表示采用(yong)(yong)(yong)(yong)國際標準IS07388號加工中心機床(chuang)用(yong)(yong)(yong)(yong)錐(zhui)柄(bing)(bing)柄(bing)(bing)部(bu)(bu)(帶機械手(shou)夾持(chi)槽(cao));其后數字為相(xiang)(xiang)(xiang)應(ying)的(de)(de)(de)ISO錐(zhui)度號。BT:表示采用(yong)(yong)(yong)(yong)日本標準MAS403號加工中心機床(chuang)用(yong)(yong)(yong)(yong)錐(zhui)柄(bing)(bing)柄(bing)(bing)部(bu)(bu)(帶機械手(shou)夾持(chi)槽(cao));其后數字為相(xiang)(xiang)(xiang)應(ying)的(de)(de)(de)ISO錐(zhui)度號。對于高(gao)速(su)切削一般采用(yong)(yong)(yong)(yong)HSK系(xi)列(lie)刀(dao)(dao)柄(bing)(bing)。
為提高(gao)加(jia)工效率,應盡可能選(xuan)用(yong)(yong)高(gao)效率的刀(dao)具和刀(dao)柄(bing)。選(xuan)用(yong)(yong)強力銑(xian)夾(jia)頭刀(dao)柄(bing),夾(jia)持精度(du)(du)高(gao),可以用(yong)(yong)來夾(jia)持直(zhi)柄(bing)刀(dao)具,因卡簧自(zi)(zi)身夾(jia)緊變形小(xiao)自(zi)(zi)鎖性好,夾(jia)緊力大(da),可以用(yong)(yong)于強力銑(xian)削加(jia)工;還可以用(yong)(yong)于高(gao)精度(du)(du)銑(xian)鉸(jiao)孔加(jia)工,也可通(tong)過接桿夾(jia)持帶孔類(lei)刀(dao)具。
選(xuan)用(yong)(yong)(yong)(yong)彈簧卡(ka)頭刀(dao)(dao)(dao)(dao)(dao)(dao)柄,卡(ka)簧彈性(xing)變(bian)形量為(wei)1mm,主要(yao)夾持(chi)小(xiao)規格(ge)(ge)銑(xian)刀(dao)(dao)(dao)(dao)(dao)(dao),如(ru)鉆頭、銑(xian)刀(dao)(dao)(dao)(dao)(dao)(dao)、鉸(jiao)刀(dao)(dao)(dao)(dao)(dao)(dao)、絲錐等。選(xuan)用(yong)(yong)(yong)(yong)模(mo)塊(kuai)式工(gong)(gong)(gong)(gong)具(ju)(ju)系統由(you)于(yu)其定(ding)位精度高(gao),裝卸方便,連(lian)接(jie)剛性(xing)好(hao),具(ju)(ju)有良好(hao)的抗振(zhen)性(xing),是目前用(yong)(yong)(yong)(yong)得較多(duo)的一種型式,它由(you)刀(dao)(dao)(dao)(dao)(dao)(dao)柄、中間接(jie)桿以(yi)及(ji)工(gong)(gong)(gong)(gong)作頭組(zu)成。選(xuan)用(yong)(yong)(yong)(yong)粗鏜孔可(ke)選(xuan)用(yong)(yong)(yong)(yong)雙刃鏜刀(dao)(dao)(dao)(dao)(dao)(dao)刀(dao)(dao)(dao)(dao)(dao)(dao)柄,既可(ke)提高(gao)加工(gong)(gong)(gong)(gong)效率,又(you)有利(li)于(yu)減少切(qie)削(xue)振(zhen)動;對于(yu)批量大(da)、加工(gong)(gong)(gong)(gong)復(fu)雜的典型工(gong)(gong)(gong)(gong)件,應盡(jin)(jin)可(ke)能選(xuan)用(yong)(yong)(yong)(yong)復(fu)合刀(dao)(dao)(dao)(dao)(dao)(dao)具(ju)(ju)。盡(jin)(jin)管(guan)復(fu)合刀(dao)(dao)(dao)(dao)(dao)(dao)具(ju)(ju)與刀(dao)(dao)(dao)(dao)(dao)(dao)柄價格(ge)(ge)較為(wei)昂貴,但在數控(kong)機(ji)床上采用(yong)(yong)(yong)(yong)復(fu)合刀(dao)(dao)(dao)(dao)(dao)(dao)具(ju)(ju)加工(gong)(gong)(gong)(gong),可(ke)以(yi)使工(gong)(gong)(gong)(gong)序集(ji)中,把多(duo)道工(gong)(gong)(gong)(gong)序合并成一道工(gong)(gong)(gong)(gong)序、由(you)一把刀(dao)(dao)(dao)(dao)(dao)(dao)具(ju)(ju)完成,有利(li)于(yu)減少加工(gong)(gong)(gong)(gong)時間和換刀(dao)(dao)(dao)(dao)(dao)(dao)次數,顯著提高(gao)生產效率。
(2)數控銑床刀具的分類
數控銑床刀(dao)(dao)具(ju)的(de)分類(lei)有多種方法,根據刀(dao)(dao)具(ju)結構可(ke)分為(wei):①整體(ti)式(shi)(shi)②鑲(xiang)嵌式(shi)(shi),采(cai)用焊接或機(ji)夾式(shi)(shi)連(lian)接,機(ji)夾式(shi)(shi)又可(ke)分為(wei)可(ke)轉(zhuan)位和不可(ke)轉(zhuan)位兩(liang)種③特殊型式(shi)(shi),如復合式(shi)(shi)刀(dao)(dao)具(ju),減震式(shi)(shi)刀(dao)(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金剛石刀(dao)具④陶瓷(ci)刀(dao)片材料如氮(dan)化硅陶瓷(ci)Si3N4,立方(fang)氮(dan)化硼CBN。
從切(qie)削工藝上(shang)可分為:銑(xian)(xian)削類(lei)刀具(面銑(xian)(xian)刀、立銑(xian)(xian)刀、圓鼻(bi)刀、球頭銑(xian)(xian)刀、錐度銑(xian)(xian)刀)、孔加工類(lei)刀具(麻(ma)花鉆、鉸刀、鏜刀、絲錐等)。
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%,金屬切除量占總數的80%~90%。
二、數控加工刀具的選擇
刀具(ju)(ju)選(xuan)擇的(de)總原則:安裝調(diao)整方便、可靠性好、剛性好、耐用度和精度高。在滿足(zu)加工要求的(de)前提下(xia),盡量(liang)選(xuan)擇刀柄較短的(de)刀具(ju)(ju),以增強加工的(de)剛性。
(1)根據工件的表面尺寸選擇刀具
選取(qu)刀(dao)(dao)(dao)(dao)(dao)(dao)具時,要使刀(dao)(dao)(dao)(dao)(dao)(dao)具的尺(chi)(chi)寸與被加(jia)工(gong)(gong)件(jian)的表(biao)面(mian)(mian)尺(chi)(chi)寸相適應(ying)用(yong)。生產中(zhong),加(jia)工(gong)(gong)平面(mian)(mian)零件(jian)周(zhou)邊的輪廓(kuo),常采(cai)用(yong)立銑(xian)刀(dao)(dao)(dao)(dao)(dao)(dao);銑(xian)削(xue)平面(mian)(mian),應(ying)選硬質合(he)金刀(dao)(dao)(dao)(dao)(dao)(dao)片銑(xian)刀(dao)(dao)(dao)(dao)(dao)(dao)。加(jia)工(gong)(gong)凸臺、凹(ao)槽時,選高(gao)速(su)鋼立銑(xian)刀(dao)(dao)(dao)(dao)(dao)(dao);加(jia)工(gong)(gong)毛坯表(biao)面(mian)(mian)或孔粗(cu)加(jia)工(gong)(gong)時,可選用(yong)鑲硬質合(he)金刀(dao)(dao)(dao)(dao)(dao)(dao)片的玉米銑(xian)刀(dao)(dao)(dao)(dao)(dao)(dao);對一些立體型面(mian)(mian)和變(bian)斜面(mian)(mian)輪廓(kuo)外形(xing)的加(jia)工(gong)(gong),選用(yong)盤(pan)形(xing)銑(xian)刀(dao)(dao)(dao)(dao)(dao)(dao)、圓(yuan)鼻刀(dao)(dao)(dao)(dao)(dao)(dao)、平刀(dao)(dao)(dao)(dao)(dao)(dao)做(zuo)粗(cu)加(jia)工(gong)(gong),選用(yong)球頭(tou)銑(xian)刀(dao)(dao)(dao)(dao)(dao)(dao)、環形(xing)銑(xian)刀(dao)(dao)(dao)(dao)(dao)(dao)、錐形(xing)銑(xian)刀(dao)(dao)(dao)(dao)(dao)(dao)做(zuo)精加(jia)工(gong)(gong)。
(2)根據工件的表面形狀選擇刀具
在進(jin)行(xing)模(mo)具(ju)(ju)(ju)加(jia)(jia)工(gong)(gong)時(shi),由于(yu)球頭(tou)(tou)(tou)刀(dao)(dao)具(ju)(ju)(ju)的(de)(de)端部(bu)切削速度(du)為(wei)零,因此,為(wei)保證加(jia)(jia)工(gong)(gong)精度(du),切削行(xing)距(ju)一般采用(yong)頂端密距(ju),故球頭(tou)(tou)(tou)銑(xian)刀(dao)(dao)常用(yong)于(yu)曲面的(de)(de)精加(jia)(jia)工(gong)(gong)。而平(ping)頭(tou)(tou)(tou)刀(dao)(dao)具(ju)(ju)(ju)在表面加(jia)(jia)工(gong)(gong)質(zhi)量(liang)和(he)(he)切削效率(lv)方面都優于(yu)球頭(tou)(tou)(tou)刀(dao)(dao),因此,只要在保證不過切的(de)(de)前提下,無論是(shi)曲面的(de)(de)粗加(jia)(jia)工(gong)(gong)還是(shi)精加(jia)(jia)工(gong)(gong),都應(ying)優先選(xuan)擇平(ping)頭(tou)(tou)(tou)刀(dao)(dao)。另(ling)外,刀(dao)(dao)具(ju)(ju)(ju)的(de)(de)耐用(yong)度(du)和(he)(he)精度(du)與刀(dao)(dao)具(ju)(ju)(ju)價(jia)格(ge)關系極大,必(bi)須引(yin)起注意(yi)的(de)(de)是(shi),在大多數情況下,選(xuan)擇好的(de)(de)刀(dao)(dao)具(ju)(ju)(ju)雖(sui)然增加(jia)(jia)了刀(dao)(dao)具(ju)(ju)(ju)成本,但由此帶來的(de)(de)加(jia)(jia)工(gong)(gong)質(zhi)量(liang)和(he)(he)加(jia)(jia)工(gong)(gong)效率(lv)的(de)(de)提高(gao),則(ze)可以使整個加(jia)(jia)工(gong)(gong)成本大大降低。
(3)合理安排刀具的排列順序
在經濟型數控機(ji)床(chuang)的(de)加工過程中,由于刀(dao)(dao)具(ju)(ju)的(de)磨損、測量和更換多為人(ren)工手(shou)動進(jin)行,占用輔助時間(jian)較長,因此,必須(xu)合(he)理安排(pai)刀(dao)(dao)具(ju)(ju)的(de)排(pai)列順序(xu)。一(yi)(yi)般應(ying)(ying)遵循(xun)以下原則:①工序(xu)集中一(yi)(yi)次裝夾(jia),同一(yi)(yi)把刀(dao)(dao)具(ju)(ju)能完成其進(jin)行的(de)所有(you)加工步驟;②粗精加工的(de)刀(dao)(dao)具(ju)(ju)應(ying)(ying)分開使用;③先面后孔(kong);④先進(jin)行曲面精加工,后進(jin)行二維輪廓(kuo)精加工;⑤合(he)理利用數控機(ji)床(chuang)的(de)自(zi)動換刀(dao)(dao)功(gong)能,以提高生(sheng)產效率;⑥盡(jin)量減少刀(dao)(dao)具(ju)(ju)數量。