數控機床的選型風險控製

    數控機床是一種先進的加工設備，它以高精度
、高可靠性
、高效率
、可(ke)加(jia)工(gong)複(fu)雜(za)曲(qu)麵(mian)工(gong)件(jian)等(deng)特(te)點(dian)得(de)到(dao)廣(guang)泛(fan)應(ying)用(yong)。但(dan)若(ruo)選(xuan)型(xing)不(bu)當(dang)，則(ze)不(bu)能(neng)發(fa)揮(hui)其(qi)應(ying)有(you)的(de)效(xiao)益(yi)，且(qie)使(shi)資(zi)金(jin)大(da)量(liang)積(ji)壓(ya)，從(cong)而(er)產(chan)生(sheng)風(feng)險(xian)。廣(guang)義(yi)的(de)選(xuan)型(xing)主(zhu)要(yao)包(bao)括(kuo)機(ji)型(xing)選(xuan)擇(ze)、數控係統選擇、機床精度選擇、主(zhu)要(yao)特(te)征(zheng)規(gui)格(ge)選(xuan)擇(ze)等(deng)。其(qi)中(zhong)機(ji)型(xing)選(xuan)擇(ze)和(he)數(shu)控(kong)係(xi)統(tong)選(xuan)擇(ze)風(feng)險(xian)最(zui)大(da)
，機(ji)床(chuang)精(jing)度(du)和(he)主(zhu)要(yao)特(te)征(zheng)規(gui)格(ge)選(xuan)擇(ze)次(ci)之(zhi)
，故(gu)要(yao)減(jian)少(shao)選(xuan)型(xing)風(feng)險(xian)，可(ke)從(cong)以(yi)下(xia)幾(ji)方(fang)麵(mian)著(zhe)手(shou)。
　　
　一、機型選擇

　zaimanzujiagonggongyiyaoqiudeqiantixiashebeiyuejiandanfengxianyuexiao

，chexuejiagongzhongxinheshukongchechuangdoukeyijiagongzhouleilingjian，danyitaimanzutongyangjiagongguigedechexuezhongxinjiageyaobishukongchechuangguijibei，ruguomeiyoujinyibugongyiyaoqiu，kendingxuanzeshukongchechuangfengxianjiaoxiao。tongyangzaijingjixingheputongxingshukongchechuangzhongyaojinliangxuanzejingjixingshukongchechuang。zaijiagongxiangti、型腔、模具零件中，同規格的數控銑床和加工中心都能滿足基本加工要求

，但兩種機床價格相差約一半（不包括氣源、刀庫等配套費用），suoyimojujiagongzhongzhiyoufeichangpinfandihuandaojudegongyicaixuanyongjiagongzhongxin
，gudingyibadaojuchangshijianxixuede，xuanyongshukongxichuang。muqianhenduojiagongzhongxindouzaizuoshukongxichuangshiyong。shukongchechuangnengjiagongdelingjianputongchechuangwangwangyenengjiagong，danshukongxichuangnengjiagongdelingjianputongxichuangdaduobunengjiagong，guzaijiyouzhouleilingjianyouyouxiangti
、型腔類零件的綜合機加工企業中應優先選擇數控銑床。
　　
　二、數控係統選擇

　在(zai)選(xuan)購(gou)數(shu)控(kong)機(ji)床(chuang)時(shi)，同(tong)一(yi)種(zhong)機(ji)床(chuang)本(ben)體(ti)可(ke)配(pei)置(zhi)多(duo)種(zhong)數(shu)控(kong)係(xi)統(tong)。在(zai)可(ke)供(gong)選(xuan)擇(ze)的(de)係(xi)統(tong)中(zhong)，性(xing)能(neng)高(gao)低(di)差(cha)別(bie)很(hen)大(da)，直(zhi)接(jie)影(ying)響(xiang)到(dao)設(she)備(bei)價(jia)格(ge)構(gou)成(cheng)。目(mu)前(qian)數(shu)控(kong)係(xi)統(tong)種(zhong)類(lei)、規格極其繁多，進口係統主要有日本FANUC、德國SINUMERIK
、日本MITSUBISHI、法國NUM、意大利FIDIA、西班牙FAGOR、美國A-B等。國產係統主要有廣州係統、航天係統、華中係統、遼寧藍天係統、南京大方係統、北方凱奇係統、清華係統

、KND係統等
，每家公司都有一係列各種規格的產品。減少數控係統選型風險的基本原則是：性能價格比大，使用維修方便
，係統的市場壽命長。因此不能片麵追求高水平
、xinxitong。eryinggaiyimanzuzhujixingnengweizhu，duixitongxingnenghejiagedengzuoyigezonghefenxi
，xuanyongheshixitong。tongshiyingzhujianshaoxuanchuantongdefengbitixijiegoudeshukongxitonghuoPC嵌入NC結構的數控係統，因為這類係統的功能擴展、改變和維修都必須借助於係統供應商。應盡可能選用NC嵌入PC結構或SOFT結構的開放式數控係統，這類係統的CNC軟件全部裝在計算機中，而硬件部分僅是計算機與伺服驅動和外部1/O之間的標準化通用接口，就像計算機上可以安裝各種品牌的聲卡、顯卡和對應的驅動程序一樣，用戶可以在WINDOWSNT平台上，利用開放的CNC內nei核he，開kai發fa所suo需xu的de功gong能neng，構gou成cheng各ge種zhong類lei型xing的de數shu控kong係xi統tong。另ling外wai數shu控kong係xi統tong中zhong基ji本ben功gong能neng以yi外wai還hai有you很hen多duo選xuan擇ze功gong能neng
，用yong戶hu可ke以yi根gen據ju自zi己ji的de工gong件jian加jia工gong要yao求qiu、測量要求、程序編製要求等，額外再選擇一些功能列入訂貨合同附件中，特別是實時傳輸的DNC功能等。
　
　三
、精度選擇

　數控機床精度等級的選擇取決於典型零件的加工精度。一般數控機床精度檢驗項目都有20~30項，但其最有特征的項目是：單軸定位精度、單軸重複定位精度、liangzhouyishangliandongjiagongchulaishijiandeyuandu。dingweijingduhezhongfudingweijingduzonghefanyinglegaizhougeyundongbujiandezonghejingdu。danzhoudingweijingdushizhizaigaizhouxingchengneirenyiyigediandingweishidewuchafanwei，tazhijiefanyinglejichuangdejiagongjingdunengli
，erzhongfudingweijingduzefanyinglegaizhouzaixingchengneirenyidingweidiandedingweiwendingxing，zheshihenglianggaizhounengfouwendingkekaogongzuodejibenzhibiao。yishanglianggezhibiaozhong，zhongfudingweijingduyouweizhongyao。muqianshukongxitongzhongruanjiandouyoufengfudewuchabuchanggongneng，nengduijingeichuandonglianshanggehuanjiexitongwuchajinxingwendingdebuchang。rusigangdeluojuwuchaheleijiwuchakeyiyongluojubuchanggongnengbuchang，jingeichuandongliandefanxiangsiqukeyongfanxiangjianxibuchanglaixiaochu。dandiankongfangmianwuchabuchanggongnengbukenengbuchangsuijiwucha（如傳動鏈各環節的間隙
、彈性變形和接觸剛度等因素變化產生的誤差）
，它們往往隨著工作台的負載大小、移動距離長短、yidongdingweisududekuaimandengfanyingchubutongdeyundongliangsunshi。zaiyixiekaihuanhebanbihuanjingeisifuxitongzhong，celiangyuanjianyihoudejixiequdongyuanjian，shougezhongouranyinsuyingxiang，yeyouxiangdangdadesuijiwuchayingxiang，lirugunzhusigangreshenchangyinqidegongzuotaishijidingweiweizhipiaoyideng。suoyizhongfudingweijingdudehelixuanzekedadajianshaojingduxuanzefengxian。xixueyuanzhumianjingduhuoxixuekongjianluoxuancao（螺紋）精度是綜合評價該機床有關數控軸（兩軸或三軸）伺(si)服(fu)跟(gen)隨(sui)運(yun)動(dong)特(te)性(xing)和(he)數(shu)控(kong)係(xi)統(tong)插(cha)補(bu)功(gong)能(neng)的(de)指(zhi)標(biao)
，評(ping)價(jia)指(zhi)標(biao)采(cai)用(yong)測(ce)量(liang)加(jia)工(gong)出(chu)的(de)圓(yuan)柱(zhu)麵(mian)的(de)圓(yuan)度(du)。在(zai)數(shu)控(kong)銑(xi)床(chuang)試(shi)切(qie)件(jian)中(zhong)還(hai)有(you)銑(xi)斜(xie)方(fang)形(xing)四(si)邊(bian)加(jia)工(gong)，這(zhe)也(ye)是(shi)判(pan)斷(duan)兩(liang)個(ge)可(ke)控(kong)軸(zhou)在(zai)直(zhi)線(xian)插(cha)補(bu)運(yun)動(dong)時(shi)精(jing)度(du)的(de)一(yi)種(zhong)方(fang)法(fa)。對(dui)於(yu)數(shu)控(kong)銑(xi)床(chuang)，兩(liang)軸(zhou)以(yi)上(shang)聯(lian)動(dong)加(jia)工(gong)出(chu)來(lai)試(shi)件(jian)的(de)圓(yuan)度(du)指(zhi)標(biao)也(ye)不(bu)容(rong)忽(hu)略(lve)。定(ding)位(wei)精(jing)度(du)要(yao)求(qiu)較(jiao)高(gao)的(de)機(ji)床(chuang)還(hai)必(bi)須(xu)注(zhu)意(yi)它(ta)的(de)進(jin)給(gei)伺(si)服(fu)係(xi)統(tong)采(cai)用(yong)半(ban)閉(bi)環(huan)方(fang)式(shi)還(hai)是(shi)全(quan)閉(bi)環(huan)方(fang)式(shi)，注(zhu)意(yi)使(shi)用(yong)檢(jian)測(ce)元(yuan)件(jian)的(de)精(jing)度(du)及(ji)穩(wen)定(ding)性(xing)。如(ru)機(ji)床(chuang)采(cai)用(yong)半(ban)閉(bi)環(huan)伺(si)服(fu)驅(qu)動(dong)方(fang)式(shi)，則(ze)精(jing)度(du)穩(wen)定(ding)性(xing)要(yao)受(shou)到(dao)一(yi)些(xie)外(wai)界(jie)因(yin)素(su)影(ying)響(xiang)，如(ru)傳(chuan)動(dong)鏈(lian)中(zhong)滾(gun)珠(zhu)絲(si)杠(gang)受(shou)工(gong)作(zuo)溫(wen)度(du)變(bian)化(hua)造(zao)成(cheng)絲(si)杠(gang)伸(shen)長(chang)，對(dui)工(gong)作(zuo)台(tai)實(shi)際(ji)定(ding)位(wei)位(wei)置(zhi)造(zao)成(cheng)漂(piao)移(yi)影(ying)響(xiang)，使(shi)加(jia)工(gong)件(jian)的(de)加(jia)工(gong)精(jing)度(du)受(shou)到(dao)影(ying)響(xiang)。
　　
　四
、數控機床主要特征規格選擇

　數(shu)控(kong)機(ji)床(chuang)的(de)主(zhu)要(yao)特(te)征(zheng)規(gui)格(ge)應(ying)根(gen)據(ju)確(que)定(ding)的(de)典(dian)型(xing)工(gong)件(jian)族(zu)加(jia)工(gong)尺(chi)寸(cun)範(fan)圍(wei)而(er)選(xuan)擇(ze)。數(shu)控(kong)機(ji)床(chuang)的(de)最(zui)主(zhu)要(yao)規(gui)格(ge)是(shi)幾(ji)個(ge)數(shu)控(kong)軸(zhou)的(de)行(xing)程(cheng)範(fan)圍(wei)和(he)主(zhu)軸(zhou)電(dian)機(ji)功(gong)率(lv)。機(ji)床(chuang)的(de)三(san)個(ge)基(ji)本(ben)直(zhi)線(xian)坐(zuo)標(biao)（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範圍之內
，如典型工件是450mm×450mm×450mm的箱體，那麼應選取工作台麵尺寸為500mm×500mm的(de)加(jia)工(gong)中(zhong)心(xin)，選(xuan)用(yong)工(gong)作(zuo)台(tai)麵(mian)比(bi)典(dian)型(xing)工(gong)件(jian)稍(shao)大(da)一(yi)些(xie)是(shi)考(kao)慮(lv)到(dao)安(an)裝(zhuang)夾(jia)具(ju)所(suo)需(xu)的(de)空(kong)間(jian)。機(ji)床(chuang)工(gong)作(zuo)台(tai)麵(mian)尺(chi)寸(cun)和(he)三(san)個(ge)直(zhi)線(xian)坐(zuo)標(biao)行(xing)程(cheng)都(dou)有(you)一(yi)定(ding)比(bi)例(li)關(guan)係(xi)，如(ru)上(shang)述(shu)工(gong)作(zuo)台(tai)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(yin)此(ci)，工(gong)作(zuo)台(tai)麵(mian)的(de)大(da)小(xiao)基(ji)本(ben)上(shang)確(que)定(ding)了(le)加(jia)工(gong)空(kong)間(jian)的(de)大(da)小(xiao)。個(ge)別(bie)情(qing)況(kuang)下(xia)也(ye)可(ke)以(yi)有(you)工(gong)件(jian)尺(chi)寸(cun)大(da)於(yu)坐(zuo)標(biao)行(xing)程(cheng)
，這(zhe)時(shi)必(bi)須(xu)要(yao)求(qiu)零(ling)件(jian)上(shang)的(de)加(jia)工(gong)區(qu)域(yu)處(chu)在(zai)行(xing)程(cheng)範(fan)圍(wei)之(zhi)內(nei)，而(er)且(qie)要(yao)考(kao)慮(lv)機(ji)床(chuang)工(gong)作(zuo)台(tai)的(de)允(yun)許(xu)承(cheng)載(zai)能(neng)力(li)
，以(yi)及(ji)工(gong)件(jian)是(shi)否(fou)與(yu)機(ji)床(chuang)換(huan)刀(dao)空(kong)間(jian)幹(gan)涉(she)、yujichuangfanghuzhaodengfujianganshedengyixiliewenti。shukongjichuangdezhudianjigonglvzaitongleiguigejichuangshangyekeyiyougezhongbutongpeizhi，yibanqingkuangxiafanyinglegaijichuangdeqiexuegangxinghezhuzhougaosuxingneng。qingxingjichuangbibiaozhunxingjichuangzhuzhoudianjigonglvjiukenengxiao1~2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qi主zhu軸zhou電dian機ji功gong率lv也ye成cheng倍bei加jia大da。主zhu軸zhou電dian機ji功gong率lv反fan映ying了le機ji床chuang的de切qie削xue效xiao率lv，從cong另ling一yi個ge側ce麵mian也ye反fan映ying了le切qie削xue剛gang性xing和he機ji床chuang整zheng體ti剛gang度du。在zai現xian代dai中zhong小xiao型xing數shu控kong機ji床chuang中zhong，主zhu軸zhou箱xiang的de機ji械xie變bian速su已yi較jiao少shao采cai用yong，往wang往wang都dou采cai用yong功gong率lv較jiao大da的de直zhi流liu或huo交jiao流liu可ke調tiao速su電dian機ji直zhi聯lian主zhu軸zhou
，甚shen至zhi采cai用yong電dian主zhu軸zhou結jie構gou
，這zhe樣yang的de結jie構gou在zai低di速su切qie削xue中zhong扭niu矩ju受shou到dao限xian製zhi，即ji調tiao速su電dian機ji在zai低di轉zhuan速su時shi輸shu出chu功gong率lv下xia降jiang，為wei了le確que保bao低di速su輸shu出chu扭niu矩ju
，必bi須xu采cai用yong大da功gong率lv電dian機ji。所suo以yi同tong規gui格ge機ji床chuang數shu控kong機ji床chuang主zhu軸zhou電dian機ji比bi普pu通tong機ji床chuang大da幾ji倍bei。當dang典dian型xing工gong件jian上shang有you大da量liang的de低di速su加jia工gong時shi
，必bi須xu對dui機ji床chuang的de低di速su輸shu出chu扭niu矩ju進jin行xing校xiao核he。