數控銑床加(jia)工(gong)的(de)工(gong)件(jian)(jian)一(yi)般都比較(jiao)復雜(za),也(ye)(ye)經常(chang)用到一(yi)些夾具,這樣既(ji)有(you)利(li)于(yu)提高加(jia)工(gong)效率也(ye)(ye)利(li)于(yu)保證加(jia)工(gong)精度(du)。本(ben)人在實際批(pi)量(liang)生產加(jia)工(gong)一(yi)種電子秤(cheng)的(de)零(ling)件(jian)(jian)時,就曾遇到了帶有(you)曲線對(dui)稱零(ling)件(jian)(jian)的(de)正(zheng)、反面加(jia)工(gong)倒角的(de)問題(ti)。
針對這類零(ling)件我設計了一(yi)套(tao)夾具(ju),用此夾具(ju)裝(zhuang)夾工(gong)(gong)件進行加工(gong)(gong)時(shi),能有(you)效(xiao)地減少工(gong)(gong)件的裝(zhuang)夾和(he)定(ding)位時(shi)間,提高了加工(gong)(gong)效(xiao)率和(he)加工(gong)(gong)精度,工(gong)(gong)件批(pi)量較大(da)(da)時(shi)價值更加明顯。下面將具(ju)體闡述以供(gong)大(da)(da)家參(can)考。
1.問題提出
數控銑(xian)床加(jia)(jia)工(gong)(gong)(gong)(gong)吊耳零件(如(ru)圖1所(suo)示)時(shi)要求倒(dao)角(jiao)(jiao)2mm×45°,工(gong)(gong)(gong)(gong)件其他(ta)工(gong)(gong)(gong)(gong)序已經(jing)完成,兩大面(mian)已經(jing)加(jia)(jia)工(gong)(gong)(gong)(gong)好,兩個孔已經(jing)鏜削加(jia)(jia)工(gong)(gong)(gong)(gong)完畢(bi),外(wai)(wai)圓(yuan)(yuan)弧余量2～3mm。在數控銑(xian)床上(shang)要求加(jia)(jia)工(gong)(gong)(gong)(gong)周邊圓(yuan)(yuan)弧和倒(dao)角(jiao)(jiao),圓(yuan)(yuan)弧邊一(yi)次(ci)裝夾可(ke)以加(jia)(jia)工(gong)(gong)(gong)(gong)完成,但是倒(dao)角(jiao)(jiao)需要正(zheng)、反(fan)兩次(ci)裝夾才(cai)可(ke)以完成。在加(jia)(jia)工(gong)(gong)(gong)(gong)時(shi)外(wai)(wai)圓(yuan)(yuan)弧采用直徑40mm的銑(xian)刀全(quan)厚度(du)加(jia)(jia)工(gong)(gong)(gong)(gong),為了提高效率(lv)不分層(ceng)。具體(ti)加(jia)(jia)工(gong)(gong)(gong)(gong)工(gong)(gong)(gong)(gong)藝過程:工(gong)(gong)(gong)(gong)件找正(zheng)→加(jia)(jia)工(gong)(gong)(gong)(gong)外(wai)(wai)圓(yuan)(yuan)弧→倒(dao)角(jiao)(jiao)→翻面(mian)裝夾→進行反(fan)面(mian)倒(dao)角(jiao)(jiao)。這時(shi)關(guan)鍵就在于正(zheng)、反(fan)兩面(mian)要求倒(dao)角(jiao)(jiao)均勻一(yi)致(zhi),在加(jia)(jia)工(gong)(gong)(gong)(gong)過程中(zhong)會存在以下幾(ji)個問(wen)題:
(1)工件在找(zhao)正時存在不便(bian)。從圖(tu)1可以看(kan)出(chu)這個工件只能以中(zhong)心孔(kong)(kong)來(lai)進行定(ding)位(wei)裝夾,而找(zhao)平(ping)兩個孔(kong)(kong)中(zhong)心連線(xian)是(shi)(shi)比較費時、費事的,更何(he)況(kuang)是(shi)(shi)批量生(sheng)產。
(2)就算找(zhao)正了工(gong)件,加(jia)工(gong)中也會(hui)出(chu)現問題,外圓(yuan)弧還好控(kong)制,但(dan)是兩邊的(de)倒角就不好保(bao)證了。經常(chang)是正面(mian)(mian)加(jia)工(gong)合格,反面(mian)(mian)加(jia)工(gong)的(de)時候(hou),反面(mian)(mian)的(de)圓(yuan)弧就會(hui)出(chu)現一邊過切一邊切不到的(de)情況。
(3)此工件基本上每(mei)個月(yue)都要加工一(yi)批(pi),每(mei)批(pi)在50～100件不等。
綜上所述,在實(shi)際加(jia)工過(guo)程中有(you)必(bi)要設計和制作一(yi)個(ge)簡單(dan)的夾具,能使(shi)工件(jian)進行簡便、快(kuai)速、準確的定位裝夾,以保證加(jia)工時(shi)的圓弧精(jing)度和倒角精(jing)度,而且夾具力(li)求結構簡單(dan),制作方便,有(you)一(yi)定的通(tong)用性,可供長期使(shi)用。
2.問題分析
于這種加工要求的(de)工件,首(shou)先是(shi)如(ru)何能準(zhun)確(que)地進(jin)行(xing)(xing)定位裝夾(jia)(jia)(jia),找正是(shi)關鍵(jian)。工件以兩個(ge)孔來進(jin)行(xing)(xing)定位裝夾(jia)(jia)(jia),一(yi)般都采用(yong)一(yi)柱一(yi)銷的(de)方(fang)法。所以我們首(shou)先采用(yong)了圖2所示的(de)夾(jia)(jia)(jia)具來進(jin)行(xing)(xing)工件的(de)裝夾(jia)(jia)(jia)、加工。
墊板(ban)(ban)1支撐工(gong)(gong)(gong)(gong)件(jian),為加工(gong)(gong)(gong)(gong)外(wai)圓弧給刀具留出走刀空(kong)間,兩個孔由鏜(tang)床加工(gong)(gong)(gong)(gong),保證孔距為工(gong)(gong)(gong)(gong)件(jian)標(biao)準孔距。圓柱定位(wei)銷2、削邊定位(wei)銷5用來(lai)定位(wei)工(gong)(gong)(gong)(gong)件(jian);開口壓(ya)板(ban)(ban)3可(ke)以(yi)快速裝卸工(gong)(gong)(gong)(gong)件(jian)提高效(xiao)率(lv);T形塊6將夾具固(gu)定在工(gong)(gong)(gong)(gong)作臺上。