數控加工是指在cnc數控車床上進行零件加工的一種工藝方法，cnc數(shu)控(kong)車床加工與傳統機床加工的工藝規程從總體上說是一致的，但也發生了明顯的變化。用數字信息控制零件和刀具位移的機械加工方法。是解決零件品種多變、批量小、形狀復雜、精度高等問題和實現自動化加工的有效途徑。

三線加(jia)工(gong)中(zhong)心(xin)是一種先進的加(jia)工(gong)設備(bei)，它以高(gao)精度、高(gao)可靠性、可加(jia)工(gong)復雜(za)曲面工(gong)件等(deng)(deng)特(te)(te)點(dian)得到廣泛應(ying)用。但若選(xuan)(xuan)型(xing)(xing)不當，則不能發揮(hui)其(qi)應(ying)有的效益，且使(shi)資金大量積壓，從(cong)而產生風(feng)險。廣義(yi)的選(xuan)(xuan)型(xing)(xing)主(zhu)要包括機(ji)型(xing)(xing)選(xuan)(xuan)擇(ze)(ze)、數控系統選(xuan)(xuan)擇(ze)(ze)、機(ji)床(chuang)精度選(xuan)(xuan)擇(ze)(ze)、主(zhu)要特(te)(te)征規格選(xuan)(xuan)擇(ze)(ze)等(deng)(deng)。其(qi)中(zhong)機(ji)型(xing)(xing)選(xuan)(xuan)擇(ze)(ze)和數控系統選(xuan)(xuan)擇(ze)(ze)風(feng)險，機(ji)床(chuang)精度和主(zhu)要特(te)(te)征規格選(xuan)(xuan)擇(ze)(ze)次之，故要減少選(xuan)(xuan)型(xing)(xing)風(feng)險，可從(cong)以下(xia)幾方(fang)面著手。

一、機型選擇

在滿(man)足加(jia)(jia)(jia)工工藝(yi)(yi)要(yao)(yao)求的(de)前提下設(she)備越簡單風(feng)(feng)險(xian)(xian)越小(xiao)，車削加(jia)(jia)(jia)工中(zhong)心和(he)數(shu)(shu)控(kong)(kong)(kong)(kong)(kong)車床(chuang)(chuang)(chuang)(chuang)都可以加(jia)(jia)(jia)工軸類(lei)(lei)零(ling)件(jian)(jian)(jian)(jian)，但(dan)一(yi)臺滿(man)足同樣(yang)加(jia)(jia)(jia)工規格的(de)車削中(zhong)心價格要(yao)(yao)比數(shu)(shu)控(kong)(kong)(kong)(kong)(kong)車床(chuang)(chuang)(chuang)(chuang)貴(gui)幾倍，如果沒(mei)有進(jin)一(yi)步工藝(yi)(yi)要(yao)(yao)求，肯定選(xuan)(xuan)擇數(shu)(shu)控(kong)(kong)(kong)(kong)(kong)車床(chuang)(chuang)(chuang)(chuang)風(feng)(feng)險(xian)(xian)較小(xiao)。同樣(yang)在經濟(ji)型和(he)普通型數(shu)(shu)控(kong)(kong)(kong)(kong)(kong)車床(chuang)(chuang)(chuang)(chuang)中(zhong)要(yao)(yao)盡量選(xuan)(xuan)擇經濟(ji)型數(shu)(shu)控(kong)(kong)(kong)(kong)(kong)車床(chuang)(chuang)(chuang)(chuang)。在加(jia)(jia)(jia)工箱體(ti)、型腔(qiang)(qiang)、模(mo)具零(ling)件(jian)(jian)(jian)(jian)中(zhong)，同規格的(de)數(shu)(shu)控(kong)(kong)(kong)(kong)(kong)銑(xian)(xian)床(chuang)(chuang)(chuang)(chuang)和(he)加(jia)(jia)(jia)工中(zhong)心都能(neng)滿(man)足基本加(jia)(jia)(jia)工要(yao)(yao)求，但(dan)兩種機床(chuang)(chuang)(chuang)(chuang)價格相差約一(yi)半（不(bu)(bu)包括氣源、刀庫等配(pei)套費用(yong)），所(suo)以模(mo)具加(jia)(jia)(jia)工中(zhong)只有非常頻繁地(di)換(huan)刀具的(de)工藝(yi)(yi)才選(xuan)(xuan)用(yong)加(jia)(jia)(jia)工中(zhong)心，固(gu)定一(yi)把(ba)刀具長(chang)時(shi)間銑(xian)(xian)削的(de)，選(xuan)(xuan)用(yong)數(shu)(shu)控(kong)(kong)(kong)(kong)(kong)銑(xian)(xian)床(chuang)(chuang)(chuang)(chuang)。目前很多加(jia)(jia)(jia)工中(zhong)心都在作數(shu)(shu)控(kong)(kong)(kong)(kong)(kong)銑(xian)(xian)床(chuang)(chuang)(chuang)(chuang)使用(yong)。數(shu)(shu)控(kong)(kong)(kong)(kong)(kong)車床(chuang)(chuang)(chuang)(chuang)能(neng)加(jia)(jia)(jia)工的(de)零(ling)件(jian)(jian)(jian)(jian)普通車床(chuang)(chuang)(chuang)(chuang)往(wang)往(wang)也(ye)能(neng)加(jia)(jia)(jia)工，但(dan)數(shu)(shu)控(kong)(kong)(kong)(kong)(kong)銑(xian)(xian)床(chuang)(chuang)(chuang)(chuang)能(neng)加(jia)(jia)(jia)工的(de)零(ling)件(jian)(jian)(jian)(jian)普通銑(xian)(xian)床(chuang)(chuang)(chuang)(chuang)大多不(bu)(bu)能(neng)加(jia)(jia)(jia)工，故(gu)在既(ji)有軸類(lei)(lei)零(ling)件(jian)(jian)(jian)(jian)又有箱體(ti)、型腔(qiang)(qiang)類(lei)(lei)零(ling)件(jian)(jian)(jian)(jian)的(de)綜合(he)機加(jia)(jia)(jia)工企業(ye)中(zhong)應優先選(xuan)(xuan)擇數(shu)(shu)控(kong)(kong)(kong)(kong)(kong)銑(xian)(xian)床(chuang)(chuang)(chuang)(chuang)。

二、數控系統選(xuan)擇

在(zai)選(xuan)(xuan)購(gou)CNC加工中(zhong)(zhong)(zhong)心時(shi)，同一(yi)(yi)種(zhong)機(ji)床本(ben)(ben)體可(ke)(ke)配置多(duo)(duo)(duo)種(zhong)數(shu)(shu)控(kong)(kong)(kong)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)。在(zai)可(ke)(ke)供選(xuan)(xuan)擇(ze)的(de)(de)(de)(de)(de)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)中(zhong)(zhong)(zhong)，性能高低差別很大(da)(da)，直接影響(xiang)到設備(bei)價(jia)格構成。目前(qian)數(shu)(shu)控(kong)(kong)(kong)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)種(zhong)類(lei)、規(gui)格極其繁多(duo)(duo)(duo)，進口系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)主要(yao)(yao)有(you)日本(ben)(ben)FANUC、德國(guo)SINUMERIK、日本(ben)(ben)MITSUBISHI、法國(guo)NUM、意大(da)(da)利(li)FIDIA、西班牙(ya)FAGOR、美國(guo)A-B等。國(guo)產(chan)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)主要(yao)(yao)有(you)廣州系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)、航天系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)、華(hua)(hua)中(zhong)(zhong)(zhong)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)、遼寧(ning)藍天系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)、南京大(da)(da)方系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)、北方凱奇系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)、清華(hua)(hua)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)、KND系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)等，每家公司都有(you)一(yi)(yi)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)列各種(zhong)規(gui)格的(de)(de)(de)(de)(de)產(chan)品。減少數(shu)(shu)控(kong)(kong)(kong)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)選(xuan)(xuan)型(xing)風(feng)險的(de)(de)(de)(de)(de)基(ji)本(ben)(ben)原則是(shi)(shi)：性能價(jia)格比大(da)(da)，使用(yong)維修方便，系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)的(de)(de)(de)(de)(de)市場壽命長(chang)。因此不(bu)能片面(mian)追求(qiu)(qiu)高水(shui)平、新系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)。而應(ying)該以滿足主機(ji)性能為主，對(dui)(dui)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)性能和價(jia)格等作一(yi)(yi)個綜合(he)分析，選(xuan)(xuan)用(yong)合(he)適(shi)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)。同時(shi)應(ying)逐(zhu)漸少選(xuan)(xuan)傳統(tong)(tong)(tong)(tong)的(de)(de)(de)(de)(de)封閉體系(xi)(xi)(xi)(xi)(xi)(xi)(xi)結構的(de)(de)(de)(de)(de)數(shu)(shu)控(kong)(kong)(kong)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)或PC嵌入NC結構的(de)(de)(de)(de)(de)數(shu)(shu)控(kong)(kong)(kong)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)，因為這類(lei)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)的(de)(de)(de)(de)(de)功能擴展、改變和維修都必須借(jie)助于(yu)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)供應(ying)商。應(ying)盡可(ke)(ke)能選(xuan)(xuan)用(yong)NC嵌入PC結構或SOFT結構的(de)(de)(de)(de)(de)開放式數(shu)(shu)控(kong)(kong)(kong)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)，這類(lei)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)的(de)(de)(de)(de)(de)CNC軟件全部(bu)裝(zhuang)在(zai)計(ji)(ji)算機(ji)中(zhong)(zhong)(zhong)，而硬件部(bu)分僅是(shi)(shi)計(ji)(ji)算機(ji)與伺服驅動(dong)和外(wai)部(bu)1/O之間的(de)(de)(de)(de)(de)標(biao)準化通(tong)用(yong)接口，就像計(ji)(ji)算機(ji)上可(ke)(ke)以安裝(zhuang)各種(zhong)品牌的(de)(de)(de)(de)(de)聲卡(ka)、顯卡(ka)和對(dui)(dui)應(ying)的(de)(de)(de)(de)(de)驅動(dong)程序(xu)一(yi)(yi)樣，用(yong)戶(hu)可(ke)(ke)以在(zai)WINDOWSNT平臺上，利(li)用(yong)開放的(de)(de)(de)(de)(de)CNC內核，開發所需(xu)的(de)(de)(de)(de)(de)功能，構成各種(zhong)類(lei)型(xing)的(de)(de)(de)(de)(de)數(shu)(shu)控(kong)(kong)(kong)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)。另外(wai)數(shu)(shu)控(kong)(kong)(kong)系(xi)(xi)(xi)(xi)(xi)(xi)(xi)統(tong)(tong)(tong)(tong)中(zhong)(zhong)(zhong)基(ji)本(ben)(ben)功能以外(wai)還(huan)有(you)很多(duo)(duo)(duo)選(xuan)(xuan)擇(ze)功能，用(yong)戶(hu)可(ke)(ke)以根據自己的(de)(de)(de)(de)(de)工件加工要(yao)(yao)求(qiu)(qiu)、測量要(yao)(yao)求(qiu)(qiu)、程序(xu)編制要(yao)(yao)求(qiu)(qiu)等，額外(wai)再選(xuan)(xuan)擇(ze)一(yi)(yi)些(xie)功能列入訂(ding)貨合(he)同附(fu)件中(zhong)(zhong)(zhong)，特別是(shi)(shi)實時(shi)傳輸的(de)(de)(de)(de)(de)DNC功能等。

三、精度選擇

CNC加(jia)工中(zhong)心(xin)精(jing)(jing)(jing)(jing)(jing)度(du)(du)(du)等級(ji)的(de)(de)(de)(de)(de)選擇取決于典型零件(jian)的(de)(de)(de)(de)(de)加(jia)工精(jing)(jing)(jing)(jing)(jing)度(du)(du)(du)。一般CNC加(jia)工中(zhong)心(xin)精(jing)(jing)(jing)(jing)(jing)度(du)(du)(du)檢驗(yan)項目都有20~30項，但(dan)其有特征的(de)(de)(de)(de)(de)項目是：單(dan)軸(zhou)(zhou)定(ding)位(wei)(wei)精(jing)(jing)(jing)(jing)(jing)度(du)(du)(du)、單(dan)軸(zhou)(zhou)重(zhong)(zhong)復定(ding)位(wei)(wei)精(jing)(jing)(jing)(jing)(jing)度(du)(du)(du)、兩軸(zhou)(zhou)以(yi)上(shang)聯動(dong)加(jia)工出來(lai)試件(jian)的(de)(de)(de)(de)(de)圓(yuan)度(du)(du)(du)。定(ding)位(wei)(wei)精(jing)(jing)(jing)(jing)(jing)度(du)(du)(du)和(he)重(zhong)(zhong)復定(ding)位(wei)(wei)精(jing)(jing)(jing)(jing)(jing)度(du)(du)(du)綜合(he)(he)反(fan)映(ying)了該軸(zhou)(zhou)各運動(dong)部件(jian)的(de)(de)(de)(de)(de)綜合(he)(he)精(jing)(jing)(jing)(jing)(jing)度(du)(du)(du)。單(dan)軸(zhou)(zhou)定(ding)位(wei)(wei)精(jing)(jing)(jing)(jing)(jing)度(du)(du)(du)是指在該軸(zhou)(zhou)行程(cheng)內任意一個點(dian)定(ding)位(wei)(wei)時的(de)(de)(de)(de)(de)誤(wu)差范圍(wei)，它直接反(fan)映(ying)了機床的(de)(de)(de)(de)(de)加(jia)工精(jing)(jing)(jing)(jing)(jing)度(du)(du)(du)能(neng)(neng)力，而重(zhong)(zhong)復定(ding)位(wei)(wei)精(jing)(jing)(jing)(jing)(jing)度(du)(du)(du)則反(fan)映(ying)了該軸(zhou)(zhou)在行程(cheng)內任意定(ding)位(wei)(wei)點(dian)的(de)(de)(de)(de)(de)定(ding)位(wei)(wei)穩(wen)定(ding)性，這是衡(heng)量該軸(zhou)(zhou)能(neng)(neng)否(fou)穩(wen)定(ding)可靠工作(zuo)的(de)(de)(de)(de)(de)基本指標。以(yi)上(shang)兩個指標中(zhong)，重(zhong)(zhong)復定(ding)位(wei)(wei)精(jing)(jing)(jing)(jing)(jing)度(du)(du)(du)尤為重(zhong)(zhong)要。目前數(shu)控系(xi)統中(zhong)軟件(jian)都有豐富的(de)(de)(de)(de)(de)誤(wu)差補償功(gong)能(neng)(neng)，能(neng)(neng)對進給傳動(dong)鏈(lian)上(shang)各環節系(xi)統誤(wu)差進行穩(wen)定(ding)的(de)(de)(de)(de)(de)補償。如絲杠的(de)(de)(de)(de)(de)螺(luo)(luo)距誤(wu)差和(he)累計誤(wu)差可以(yi)用(yong)螺(luo)(luo)距補償功(gong)能(neng)(neng)補償，進給傳動(dong)鏈(lian)的(de)(de)(de)(de)(de)反(fan)向死(si)區可用(yong)反(fan)向間隙補償來(lai)xx。

但電(dian)控(kong)方(fang)(fang)(fang)面(mian)(mian)誤(wu)差(cha)(cha)補(bu)償(chang)功能不可(ke)能補(bu)償(chang)隨(sui)機(ji)誤(wu)差(cha)(cha)（如(ru)(ru)傳動(dong)(dong)鏈各環(huan)節的(de)(de)(de)間(jian)隙、彈性變形和(he)接觸剛度(du)等(deng)因(yin)素(su)(su)變化產生的(de)(de)(de)誤(wu)差(cha)(cha)），它們往往隨(sui)著工(gong)(gong)作(zuo)臺(tai)的(de)(de)(de)負載大(da)(da)(da)小、移(yi)(yi)動(dong)(dong)距離長短(duan)、移(yi)(yi)動(dong)(dong)定(ding)位(wei)速度(du)的(de)(de)(de)快(kuai)慢等(deng)反(fan)映出(chu)不同的(de)(de)(de)運動(dong)(dong)量(liang)損(sun)失。在一些開環(huan)和(he)半閉(bi)環(huan)進給伺(si)服系統(tong)中(zhong)(zhong)，測(ce)量(liang)元件(jian)(jian)(jian)以后的(de)(de)(de)機(ji)械驅(qu)動(dong)(dong)元件(jian)(jian)(jian)，受(shou)各種偶然(ran)因(yin)素(su)(su)影響(xiang)，也有相當大(da)(da)(da)的(de)(de)(de)隨(sui)機(ji)誤(wu)差(cha)(cha)影響(xiang)，例如(ru)(ru)滾珠(zhu)絲(si)杠熱伸長引(yin)起的(de)(de)(de)工(gong)(gong)作(zuo)臺(tai)實(shi)際(ji)定(ding)位(wei)位(wei)置(zhi)漂移(yi)(yi)等(deng)。所以重復定(ding)位(wei)精(jing)(jing)度(du)的(de)(de)(de)合理選(xuan)擇可(ke)大(da)(da)(da)大(da)(da)(da)減少(shao)精(jing)(jing)度(du)選(xuan)擇風險(xian)。銑(xian)削(xue)圓(yuan)(yuan)(yuan)(yuan)柱面(mian)(mian)精(jing)(jing)度(du)或銑(xian)削(xue)空(kong)間(jian)螺(luo)旋槽（螺(luo)紋）精(jing)(jing)度(du)是綜合評價(jia)該(gai)機(ji)床有關數(shu)控(kong)軸(zhou)（兩軸(zhou)或三軸(zhou)）伺(si)服跟隨(sui)運動(dong)(dong)特性和(he)數(shu)控(kong)系統(tong)插補(bu)功能的(de)(de)(de)指標，評價(jia)指標采用(yong)測(ce)量(liang)加(jia)(jia)(jia)工(gong)(gong)出(chu)的(de)(de)(de)圓(yuan)(yuan)(yuan)(yuan)柱面(mian)(mian)的(de)(de)(de)圓(yuan)(yuan)(yuan)(yuan)度(du)。在數(shu)控(kong)銑(xian)床試(shi)切件(jian)(jian)(jian)中(zhong)(zhong)還(huan)(huan)有銑(xian)斜方(fang)(fang)(fang)形四邊加(jia)(jia)(jia)工(gong)(gong)，這(zhe)也是判(pan)斷兩個可(ke)控(kong)軸(zhou)在直線(xian)插補(bu)運動(dong)(dong)時精(jing)(jing)度(du)的(de)(de)(de)一種方(fang)(fang)(fang)法(fa)。對于數(shu)控(kong)銑(xian)床，兩軸(zhou)以上聯動(dong)(dong)加(jia)(jia)(jia)工(gong)(gong)出(chu)來試(shi)件(jian)(jian)(jian)的(de)(de)(de)圓(yuan)(yuan)(yuan)(yuan)度(du)指標也不容忽(hu)略。定(ding)位(wei)精(jing)(jing)度(du)要求較高的(de)(de)(de)機(ji)床還(huan)(huan)必須注意它的(de)(de)(de)進給伺(si)服系統(tong)采用(yong)半閉(bi)環(huan)方(fang)(fang)(fang)式(shi)(shi)還(huan)(huan)是全閉(bi)環(huan)方(fang)(fang)(fang)式(shi)(shi)，注意使用(yong)檢測(ce)元件(jian)(jian)(jian)的(de)(de)(de)精(jing)(jing)度(du)及(ji)穩(wen)定(ding)性。如(ru)(ru)機(ji)床采用(yong)半閉(bi)環(huan)伺(si)服驅(qu)動(dong)(dong)方(fang)(fang)(fang)式(shi)(shi)，則精(jing)(jing)度(du)穩(wen)定(ding)性要受(shou)到(dao)(dao)一些外界因(yin)素(su)(su)影響(xiang)，如(ru)(ru)傳動(dong)(dong)鏈中(zhong)(zhong)滾珠(zhu)絲(si)杠受(shou)工(gong)(gong)作(zuo)溫度(du)變化造成(cheng)絲(si)杠伸長，對工(gong)(gong)作(zuo)臺(tai)實(shi)際(ji)定(ding)位(wei)位(wei)置(zhi)造成(cheng)漂移(yi)(yi)影響(xiang)，使加(jia)(jia)(jia)工(gong)(gong)件(jian)(jian)(jian)的(de)(de)(de)加(jia)(jia)(jia)工(gong)(gong)精(jing)(jing)度(du)受(shou)到(dao)(dao)影響(xiang)。

四、CNC加工中心(xin)主要特征(zheng)規格選擇

CNC加工中心的主要特征規格應根據確定的典型工件族加工尺寸范圍而選擇。CNC加工中心的主要規格是幾個數控軸的行程范圍和主軸電機功率。機床的三個基本直線坐標（X、Y、Z）行程反映該機床允許的加工空間，在車床中兩個坐標X、Z反映允許回轉體的大小。一般情況下加工件的輪廓尺寸應在機床的加工空間范圍之內，如典型工件是450mm×450mm×450mm的箱體，那么應選取工作臺面尺寸為500mm×500mm的加工中心，選用工作臺面比典型工件稍大一些是考慮到安裝夾具所需的空間。機床工作臺面尺寸和三個直線坐標行程都有一定比例關系，如上述工作臺500mm×500mm的機床，X軸行程一般為700~800mm,，Y軸為500~700mm，Z軸為500~600mm。因此，工作臺面的大小基本上確定了加工空間的大小。個別情況下也可以有工件尺寸大于坐標行程，這時必須要求零件上的加工區域處在行程范圍之內，而且要考慮機床工作臺的允許承載能力，以及工件是否與機床換刀空間干涉、與機床防護罩等附件干涉等一系列問題。CNC加工中心的主電機功率在同類規格機床上也可以有各種不同配置，一般情況下反映了該機床的切削剛性和主軸高速性能。輕型機床比標準型機床主軸電機功率就可能小1~2級。目前一般加工中心主軸轉速在4000~8000r/min，高速型機床立式機床可達2萬~7萬r/min，臥式機床1萬~2萬r/min，其主軸電機功率也成倍加大。主軸電機功率反映了機床的切削效率，從另一個側面也反映了切削剛性和機床整體剛度。在現代中小型CNC加工中心中，主軸箱的機械變速已較少采用，往往都采用功率較大的直流或交流可調速電機直聯主軸，甚至采用電主軸結構，這樣的結構在低速切削中扭矩受到限制，即調速電機在低轉速時輸出功率下降，為了確保低速輸出扭矩，必須采用大功率電機。所以同規格機床CNC加工中心（cnc數控車床）主軸電機比普通機床大幾倍。當典型工件上有大量的低速加工時，必須對機床的低速輸出扭矩進行校核。            //taomeizhuang.cn/