數(shù)控車床自動回轉刀架結構設計【四工位立式回轉刀架】
數(shù)控車床自動回轉刀架結構設計【四工位立式回轉刀架】,四工位立式回轉刀架,數(shù)控車床自動回轉刀架結構設計【四工位立式回轉刀架】,數(shù)控車床,自動,回轉,刀架,結構設計,四工位,立式
機電05-1班
哈爾濱理工大學
課程設計說明書
設計題目：數(shù)控車床自動回轉刀架結構設計
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學號：
姓名：
指導老師：
日期：2008.9.24
設計任務
題目：數(shù)控車床自動回轉刀架結構設計
任務：設計一臺四工位立式回轉刀架，適用于C616或C6132經(jīng)濟型數(shù)空車床。要求繪制自動回轉刀架的機械結構圖。推薦刀架所用電動機的額定功率為
90W，額定轉速1480r/min，換刀時要求刀架轉動的速度為40r/min，減速裝置的傳動比為i=37。
總體結構設計
1、 減速傳動機構的設計
普通的三項異步電動機因轉速太快，不能直接驅動刀架進行換刀，必須經(jīng)過適當?shù)臏p速。根據(jù)立式轉位刀架的結構特點，采用蝸桿副減速時最佳選擇。蝸桿副傳動可以改變運動的方向，獲得較大的傳動比，保證傳動精度和平穩(wěn)性，并且具有自鎖功能，還可以實現(xiàn)整個裝置的小型化。
2、 上刀體鎖緊與精定位機構的設計
由于刀具直接安裝在上刀體上，所以上刀體要承受全部的切削力，其鎖緊與定位的精度將直接影響工件的加工精度。本設計上刀體的鎖進玉定位機構選用端面齒盤，將上刀體和下刀體的配合面加工成梯形端面齒。當?shù)都芴幱阪i緊狀態(tài)時，上下端面齒相互嚙合，這時上刀體不能繞刀架的中心軸旋轉；換刀時電動機正轉，抬起機構使上刀體抬起，等上下端面齒脫開后，上刀體才可以繞刀架中心軸轉動，完成轉位動作。
3、 刀架抬起機構的設計
要想使上、下刀體的兩個端面齒脫離，就必須設計適合的機構使上刀體抬起。本設計選用螺桿-螺母副，在上刀體內部加工出內螺紋，當電動機通過蝸桿-渦輪帶動蝸桿繞中心軸轉動時，作為螺母的上刀體要么轉動，要么上下移動。當?shù)都芴幱阪i緊狀態(tài)時，上刀體與下刀體的端面齒相互嚙合，因為這時上刀體不能與螺桿一起轉動，所以螺桿的轉動會使上刀體向上移動。當端面齒脫離嚙合時，上刀體就與螺桿一起轉動。
設計螺桿時要求選擇適當?shù)穆菥啵员惝斅輻U轉動一定的角度時，使得上刀梯與下刀體的端面齒能夠完全脫離嚙合狀態(tài)。
下圖為自動回轉刀架的傳動機構示意圖，詳細的裝配圖在一號圖紙上。
三、自動回轉刀架的工作原理
自動回轉刀架的換刀流程如下圖。
圖上表示自動回轉刀架在換刀過程中有關銷的位置。其中上部的圓柱銷2和下部的反靠銷6起著重要作用。
當?shù)都芴幱阪i緊狀態(tài)時，兩銷的情況如圖A所示，此時反靠銷6落在圓盤7的十字槽內，上刀體4的端面齒和下刀體的端面齒處于嚙合狀態(tài)（上下端面齒在圖中未畫出）。
需要換刀時，控制系統(tǒng)發(fā)出刀架轉位信號，三項異步電動機正向旋轉，通過蝸桿副帶動蝸桿正向轉動，與螺桿配合的上刀體4逐漸抬起，上刀體4與下刀體之間的端面齒慢慢脫開；與此同時，上蓋圓盤1也隨著螺桿正向轉動（上蓋圓盤1通過圓柱銷與螺桿聯(lián)接），當轉過約時，上蓋圓盤1直槽的另一端轉到圓柱銷2的正上方，由于彈簧3的作用，圓柱銷2落入直槽內，于是上蓋圓盤1就通過圓柱銷2使得上刀體4轉動起來（此時端面齒已完全脫開）。
上蓋圓盤1、圓柱銷2以及上刀體4在正轉的過程中，反靠銷6能夠從反靠圓盤7中十字槽的左側斜坡滑出，而不影響上刀體4尋找刀位時的正向轉動。
上刀體4帶動磁鐵轉到需要的刀位時，發(fā)信盤上對應的霍爾元件輸出低電平信號，控制系統(tǒng)收到后，立即控制刀架電動機反轉，上蓋圓盤1通過圓柱銷2帶動上刀體4開始反轉，反靠銷6馬上就會落入反靠圓盤7的十字槽內，至此，完成粗定位。此時，反靠銷6從反靠圓盤7的十字槽內爬不上來，于是上刀體4停止轉動，開始下降，而上蓋圓盤1繼續(xù)反轉，其直槽的左側斜坡將圓柱銷2的頭部壓入上刀體4的銷空內，之后，上蓋圓盤1是下表面開始與圓柱銷2的頭部滑動。再次期間，上、下刀體的端面齒逐漸嚙合，實現(xiàn)精定位，經(jīng)過設定的延時時間后，刀架電動機停轉，整個換刀過程結束。
由于蝸桿副具有自鎖功能，所以刀架可以穩(wěn)定地工作。
蝸桿-渦輪減速 銷連接
上蓋圓盤旋轉
螺桿正轉
刀架電動機正轉
上刀體抬起
螺桿-螺母
端面齒錯開
霍爾元件觸發(fā)
上刀體旋轉
到位回答
圓柱銷落入上蓋圓盤
蝸桿-渦輪減速
反靠銷反靠端面齒嚙合
螺桿反轉
刀架電動機旋轉
上刀體下降，粗定位
精定位
延時鎖緊
電動機停轉
圖：自動回轉刀架的換刀流程
主要傳動部件的設計
1. 蝸桿副的設計計算
自動回轉刀架的動力源是三相異步電動機。其中蝸桿與電動機直聯(lián)，刀架轉位時蝸輪與上刀體直聯(lián)。已知電動機額定功率=90W。,額定轉速=1480r/min，上刀體設計轉速=40r/min，蝸桿副的傳動比i=/=37。刀架從轉位到鎖緊時，需要蝸桿反向，工作載荷不均勻，啟動時沖擊較大，今要求蝸桿副的使用壽命=10000h。
（1） 蝸桿的選型 GB/T10085-1988推薦采用漸開線蝸桿和錐面包絡蝸桿。本設計采用結構簡單，制造方便的漸開線型圓柱蝸桿。
（2） 蝸桿副的材料 刀架中的蝸桿副傳動的功率不大，但蝸桿轉速干，一次，蝸桿的材料選用45鋼，其螺旋齒面要淬火，硬度為45～55HRC,以提高其表面耐磨行；蝸輪的轉速較低，其材料主要考慮耐磨性，選用鑄錫磷青銅ZCuSn10P1，采用金屬模制造。
（3） 按齒面接觸疲勞強度進行設計 刀架中的蝸桿副采用閉式傳動，多因齒面膠合或點蝕而失效。因此，進行載荷計算時，先按齒面接觸疲勞強度進行設計，再按齒根彎曲疲勞強度進行校核。
按蝸輪接觸疲勞強度條件設計計算的公式
a
(4-1)
式中 a——蝸桿副的傳動中心距，單位mm；
K——載荷系數(shù)；
——作用在渦輪上的轉矩，單位N.mm；
——彈性影響系數(shù)ZE；
[]——許用接觸應力，單位為MPa。
從式4-1算出蝸桿副的中心距a之后，根據(jù)已知的傳動比i=35，
查表選擇一個合適的中心距a值，以及相應的蝸桿，蝸輪參數(shù)。
1） 確定作用在蝸輪上的轉矩,設蝸桿頭數(shù)=1，蝸桿副的傳動效率η=0.8，由電動機的額定功率=90W，可以算出蝸輪傳動的功率=η，再由蝸輪的轉速=40r/min求得作用在蝸輪上的轉矩
=9.55=9.55=25.47N·m=22923N·mm
2） 確定載荷系數(shù)K 載荷系數(shù)K= KA KB K。其中KA為使用系數(shù)，有表6-3查得， 由于工作載荷不均勻，啟動時沖擊較大，因此取KA=1.15； 為齒向分布系數(shù)，因工作載荷在啟動和停止時有變化，故取KB=1.15； 為動載系數(shù)，由于轉數(shù)不高。沖擊不大，可取K=1.05。則載荷系數(shù)K=KA KB K ≈1.39
使用系數(shù)
工作類型
I
II
III
載荷性質
均勻，無沖擊
不均勻，小沖擊
不均勻，大沖擊
每小時起動次數(shù)
<25
25-50
>50
起動載荷
小
較大
大
KA
1
1.15
1.2
3） 確定彈性影響系數(shù)ZE，鑄錫磷青銅蝸輪與鋼蝸桿相配時，從有關手冊查的彈性影響系數(shù) ZE=160Mpa 1/2；
4） 確定接觸系數(shù) 先假設蝸桿分度圓直徑d1 和傳動中心距a的比值d1/a=0.35。查表的Zp=2.9
鑄錫青銅蝸輪的基本許用接觸應力[σ]H'(MPa)
蝸輪材料
鑄造方法
蝸桿螺旋面的硬度
≤45HRC
>45HRC
鑄錫磷青銅ZCuSn10P1
砂模鑄造
150
180
金屬模鑄造
220
268
鑄錫鋅鉛青銅ZCuSn5Pb5Zn5
砂模鑄造
113
135
金屬模鑄造
128
140
5）確定許用接觸應力[] 根據(jù)蝸輪材料為鑄錫磷青銅ZCuSn10P1金屬模制造蝸桿螺旋齒面硬度大于45HRC可查表的蝸輪的基本許用應力=268MPa已知蝸桿為單頭，蝸輪每轉一轉時每個輪齒嚙合的次數(shù)j=1；蝸輪轉數(shù)=40r/min；蝸桿副的使用壽命=10000h。
則應力循環(huán)次數(shù)：
N=60j n2 =2.4 ×10 7
壽命系數(shù)：
KHN =0.693
許用接觸應力：
[σ ]=KHN×=186MPa
6）計算中心距 將以上各參數(shù)帶入4-1，求得中心距：
a = 47.1 mm
查表取a=63，已知蝸桿頭數(shù)=1，設模數(shù)m=1.6mm，得蝸桿分度圓直徑d1=28mm。這時d1/a=0.59，查表得接觸系數(shù)=2.35。因為較大，所以上述計算結果可用。
（4）蝸桿和渦輪的主要參數(shù)與幾何尺寸 由蝸桿和渦輪的基本尺寸和主要參數(shù)，算的蝸桿和渦輪的主要幾何尺寸后，即可繪制蝸桿副的工作圖。
1）蝸桿的參數(shù)與尺寸 頭數(shù)=1，模數(shù)m=1.6mm，軸向齒距=m=5.027mm軸向齒厚=0.5m=2.514mm，分度圓直徑=28，
直徑系數(shù)q==17.5，
分度圓導程角==。
取齒頂高系數(shù)=1，徑向間隙系數(shù)=0.2，
則齒頂圓直徑=+2m=31.2mm，
齒根圓直徑=-2m（+）=24.314mm。
2）渦輪參數(shù)與尺寸 齒數(shù)=60，模數(shù)m=1.6mm，
分度圓直徑為=m=96mm，
變位系數(shù)=[a-()/2]/m=0.6，
渦輪喉圓直徑為=+2m（）=101.12mm，
渦輪齒根圓直徑=-2m（-+）=94.08mm，
渦輪咽喉母圓半徑=a-/2=12.44mm。
（5）校核渦輪齒根彎曲疲勞強度 即檢驗下式是否成立：
=[]
由蝸桿頭數(shù)=1，傳動比i=35，可以計算出渦輪齒數(shù)=i=35
則渦輪的當量齒數(shù)：
==35.17
根據(jù)渦輪變位系數(shù)=0.6和當量齒數(shù)=35.17，查表的齒形系數(shù)
=2.08
螺旋角影響系數(shù)
=1-=0.977
根據(jù)渦輪的材料和制造方法，查表得渦輪基本許用彎曲應力：
=56MPa
渦輪的壽命系數(shù)：
==0.702
渦輪的許用彎曲應力：
= =39.3MPa
將數(shù)據(jù)帶入得：
可見， ，渦輪齒根的彎曲強度滿足要求。
蝸輪的基本許用彎曲應力（MPa）
蝸輪材料
鑄造方法
單側工作
雙側工作
鑄錫青銅ZCuSn10P1
砂模鑄造
40
29
金屬模鑄造
56
40
鑄錫鋅鉛青銅ZCuSn5Pb5Zn5
砂模鑄造
26
22
金屬模鑄造
32
26
鑄鋁鐵青銅ZCuAl10Fe3
砂模鑄造
80
57
金屬模鑄造
90
64
灰鑄鐵
HT150
砂模鑄造
40
28
HT200
砂模鑄造
48
34
2.螺桿的設計計算
（1） 螺距的確定 刀架轉位時，要求螺桿在轉動約 的情況下，上刀體的端面齒與下刀體的端面齒完全脫離;在鎖緊的時候，要求上下端面的嚙合深度達2mm。因此，螺桿的螺距P應滿足P>2.4mm，今取螺桿的螺距P=6mm。
（2） 確定其他參數(shù) 采用單頭梯形螺桿，頭數(shù)n=1，牙側角= 150，外螺紋大徑=50mm，牙頂間隙=0.5mm，基本牙型高度=0.5P=3mm，外螺紋牙高=3.5mm，外螺紋中徑=47mm，外螺紋小徑=43mm，螺桿螺紋部分長度H=50mm。
（3） 自鎖性能校核 螺桿-螺母材料均用45鋼，查表取摩擦系數(shù)f=0.11；再求得梯形螺旋副的當量摩擦角：
= 6.50
而螺紋升角：
= 2.33
小于當量摩擦角。因此滿足自鎖條件。
編號
無錫太湖學院
畢業(yè)設計（論文）
相關資料
題目： 換刀機器人機械系統(tǒng)的設計
信機 系 機械工程及自動化專業(yè)
學 號： 0923006
學生姓名： 王維維
指導教師： 過金超 （職稱：副教授）
（職稱： ）
2013年5月25日
目 錄
一、畢業(yè)設計（論文）開題報告
二、畢業(yè)設計（論文）外文資料翻譯及原文
三、學生“畢業(yè)論文（論文）計劃、進度、檢查及落實表”
四、實習鑒定表
無錫太湖學院
畢業(yè)設計（論文）
開題報告
題目： 換刀機器人機械系統(tǒng)的設計
信機 系 機械工程及自動化專業(yè)
學 號： 0923006
學生姓名： 王維維
指導教師： 過金超 （職稱：副教授）
（職稱： ）
2013年5月25日
課題來源
實驗室課題。
科學依據(jù)（包括課題的科學意義；國內外研究概況、水平和發(fā)展趨勢；應用前景等）
（1）課題的科學意義
當今的世界，制造業(yè)在經(jīng)濟發(fā)展中占有十分重要的地位，機械制造業(yè)更加是制造業(yè)中的支柱與核心。
（2）國內外研究概況、水平和發(fā)展趨勢
從近幾年世界上推出的機器人產(chǎn)品來看，工業(yè)機器人技術正在向智能化、模塊化和系統(tǒng)化的方向發(fā)展。其發(fā)展趨勢為：結構的模塊化和可重構化；工作環(huán)境設計的優(yōu)化和作業(yè)的柔性化，以及網(wǎng)絡化和智能化等方面。：
（3）應用現(xiàn)狀及其前景
目前工業(yè)機械手主要用于機床加工、鑄造、熱處理等方面，無論數(shù)量、品種和性能方面還是不能滿足工業(yè)發(fā)展的需要。
在國內主要是逐步擴大應用范圍，重點發(fā)展鑄造、熱處理方面的機械手，以減輕勞動強度，改善作業(yè)條件，在應用專用機械手的同時，相應的發(fā)展通用機械手，有條件的還要研制示教式機械手、計算機控制機械手和組合機械手等。將機械手各運動構件，如伸縮、擺動、升降、橫移、俯仰等機構以及根據(jù)不同類型的加緊機構，設計成典型的通用機構，所以便根據(jù)不同的作業(yè)要求選擇不同類型的基加緊機構，即可組成不同用途的機械手。既便于設計制造，有便于更換工件，擴大應用范圍。同時要提高速度，減少沖擊，正確定位，以便更好的發(fā)揮機械手的作用。
研究內容
自動換刀機器人的機械系統(tǒng),結構，機構，受力，驅動形式，傳動系統(tǒng)。
擬采取的研究方法、技術路線、實驗方案及可行性分析
（1）實驗方案
通過對目前最常用的幾種數(shù)控車床自動換刀系統(tǒng)的研究，對所研究的數(shù)控機床提出幾個最為可行的工作系統(tǒng)，通過對方案的論證分析，選擇最為理想的完成整個設計。對整個換刀裝置，各組成機構，及各個自由度的實現(xiàn)進行分析。對換刀機械手的手指夾緊力進行分析，計算，對系統(tǒng)的關鍵部位進行校核，以確保換刀可靠性。對整個設計中涉及到的液壓缸，計算確定其各個部分結構的具體尺寸，同時對活塞桿的強度，穩(wěn)定性及螺栓的強度進行校核，以確保整個系統(tǒng)工作狀態(tài)的準確可靠。
（2）研究方法
選擇最合理的換刀系統(tǒng)，通過比較，計算，設計出關鍵零件，結合前人的換刀系統(tǒng)設計出整個換刀裝置，系統(tǒng)。
研究計劃及預期成果
研究計劃：
2012年11月12日-2012年12月2日：教師下達畢業(yè)設計任務，學生初步閱讀資料，完成畢業(yè)設計開題報告。
2013年1月21日-2013年3月1日：指導畢業(yè)實習。
2013年3月4日-2013年3月15日：確定總設計方案。
2013年3月18日-2013年3月22日：總體設計（包括參數(shù)計算及結構分析計算）。
2013年3月25日-2013年4月5日：總體設計（完成參數(shù)計算及結構分析計算后繪制草圖：裝配圖）。
2013年4月8日-2013年4月26日：零件設計。
2013年4月29日-2013年5月20日：畢業(yè)論文說明書撰寫和修改工作。
預期成果：
跟緊老師的腳步，認真的完成每一步設計，完善整個機械手的設計，熟悉掌握整個系統(tǒng)的原理。在學業(yè)將要完成之時，我將大幅提高我的機械研究能力，將會成為一名優(yōu)秀的機械技術工作者。
特色或創(chuàng)新之處
快速，精確，大容量，的換刀系統(tǒng)。兼容隨機刀具定位和固定刀具定位到位達到±
0．05mm。
已具備的條件和尚需解決的問題
我已學習數(shù)控專業(yè)三年之久，掌握了一些這專業(yè)的部分知識，老師也給了一些參照資料，可以進行這方面的研究。
尚需解決的問題：
（1）設計水平移動系統(tǒng)、垂直升降系統(tǒng)和末端操作器的驅動及傳動系統(tǒng)；
（2）設計水平移動系統(tǒng)、垂直升降系統(tǒng)和末端操作器的結構；
（3）自動換刀機械手的升降機構的繪圖
（4）裝卸刀手手臂和手部結構的設計
指導教師意見
指導教師簽名：
年 月 日
教研室（學科組、研究所）意見
教研室主任簽名：
年 月 日
系意見
主管領導簽名：
年 月 日
英文原文
On the NC lathe and tool changing system
CNC machine tool numerical control machine tools (Computer numerical control machine tools) abbreviation, is provided with a program control system of automatic machine tools. The logic control system can deal with the control code or other symbolic instruction specified program, and decoding the digital code, said information carrier, through the numerical control device input. After processing by CNC device control signals, control the machine movements, by drawing the shape and size requirements, will be automatically processed by the parts.
Features: CNC machine tool operation and monitoring of all completed in the numerical control unit, it is the brain of CNC machine tools. Compared with the general machine tools, CNC machine tools has the following characteristics:
● the processing object adaptability, adapt to the characteristics of mold products such as a single production, provide the appropriate processing method for die and mould manufacturing;
● high machining accuracy, processing with stable quality;
● can coordinate linkage, processing complex shape parts;
● machining parts change, only need to change the program, can save the preparation time of production;
● the machine itself high precision, rigidity, can choose the amount of processing good, high productivity (typically 3 to 5 times that of ordinary machine tool);
The machine is a high degree of automation, reducing labor intensity;
● conducive to the production management modernization. The use of CNC machine tools and the standard code of digital information processing, information transmission, the use of computer control method, has laid the foundation for the integration of computer aided design, manufacturing and management;
● on the operators of higher quality, higher demands for the repair of the technical staff;
● high reliability.
Composition: CNC machine tools in general by the input medium, man-machine interactive equipment, CNC equipment, feed servo drive system, spindle servo drive system, the auxiliary control device, feedback apparatus and adaptive control device etc.. [4] in NC machining, NC milling processing is the most complex, need to solve most problems. NC programming of NC line in addition to CNC milling, cutting, CNC EDM, CNC lathe, CNC grinding, each with its own characteristics, servo system is the role of the motion signal is converted into the machine moving parts from the numerical control device of pulse. Concrete has the following parts: the structure of CNC machine tools.
Driver: he is driving parts of CNC machine tools, actuator, including spindle drive unit, feeding unit, spindle motor and feed motor. He through the electric or electro-hydraulic servo system to realize the spindle and feed drive under the control of numerical control device. When several feed linkage, can complete the positioning, processing line, plane curve and space curve.
The main performance
(1) the main dimensions.
(2) the spindle system.
(3) feed system.
(4) tool system.
(5) electrical. Including the main motor, servo motor specifications and power etc..
(6) cooling system. Including the cooling capacity, cooling pump output.
(7) dimensions. Expressed as length * width * height.
Development trend of CNC lathe:
High speed, precision, complex, intelligent and green is the general trend in the development of CNC machine tool technology, in recent years, made gratifying achievements in practicality and industrialization. Mainly in the:
1 machine tool composite technology to further expand with the CNC machine tool technology, composite processing technology matures, including milling - car compound, car milling compound, car - boring - drill - gear cutting compound, composite grinding, forming, composite processing, precision and efficiency of machining is greatly improved. "One machine is a processing factory", "one card, complete processing" concept is being accepted by more people, the development of compound processing machine tool is the trend of diversified.
Intelligent technology 2 CNC machine tools have a new breakthrough, in the performance of NC system has been reflected more. Such as: automatically adjust the interference anti-collision function, after the power of workpiece automatically exit safety power-off protection function, machining parts detection and automatic compensation function of learning, high precision machining parts intelligent parameter selection function, process automatic elimination of machine vibration functions into the practical stage, intelligent upgrade the function of machine and quality.
The 3 robots enable flexible combination of flexible combination of higher efficiency of robot and the host are widely used, make flexible line more flexible, extending the function, flexible line shorten further, more efficient. Robot and machining center, milling composite machine, grinder, gear processing machine tool, tool grinding machine, electric machine, sawing machine, punching machine, laser cutting machine, water cutting machine etc. various forms of flexible unit and flexible production line has already begun the application.
4 precision machining technology has the machining precision of CNC metal cutting machine tools from the yarn in the original (0.01mm) up to micron level (0.001mm), some varieties has reached about 0.05 μ M. Micro cutting and grinding machining of ultra precision CNC machine tools, precision can reach about 0.05 μ m, shape precision can reach about 0.01 μ M. Special processing precision by using optical, electrical, chemical, energy can reach nanometer level (0.001 μ m). By optimizing the design of machine tool structure, machine tool parts of ultra precision machining and precision assembly, using high precision closed loop control and temperature, vibration and other dynamic error compensation technology, improve the geometric accuracy of machine tool processing, reduce the shape of error, surface roughness, and into the submicron, nano super finishing ti
The 5 functional component to improve the performance of functional components are at a high speed, high precision, high power and intelligent direction, and obtain the mature application. A full digital AC servo motor and drive device, high technology content of the electric spindle, linear motor, torque motor, linear motion components with high performance, application of high precision spindle unit and other function parts, greatly improving the technical level of CNC machine tools.
The feed drive system of CNC lathe:
Effect of feed drive system,
The feed drive system of CNC machine tools will be received pulse command issued by the numerical control system, and the amplification and conversion machine movements carry the expected movement.
Two, the feeding transmission system requirements
In order to guarantee the machining accuracy of NC machine tool is high, the feed drive system of transmission accuracy, sensitivity high (fast response), stable work, high stiffness and friction and inertia small, service life, and can remove the transmission gap.
Category three, feed drive system
1, stepping motor servo system
Generally used for NC machine tools.
2, DC servo motor servo system
Power is stable, but because of the brush, the wear resulting in use need to change. Generally used for middle-grade CNC machine tools.
3, AC servo motor servo system
The application is extremely widespread, mainly used in high-end CNC machine tools.
4, the linear motor servo system
No intermediate transmission chain, high precision, the feed speed, no length limit; but the poor heat dissipation, protection requirements are particularly high, mainly used for high-speed machine.
Driving component four, feed system
1, the ball screw nut pair
NC machining, the rotary motion into linear motion, so the use of screw nut transmission mechanism. NC machine tools are commonly used on the ball screw, as shown in Figure 1-25, it can be a sliding friction into rolling friction, meet the basic requirements of the feed system to reduce friction. The transmission side of high efficiency, small friction, and can eliminate the gap, no reverse air travel; but the manufacturing cost is high, can not lock, size is not too big, generally used for linear feed in small CNC machine tool.
2, rotary table
In order to expand the scope of the process of NC machine tools, CNC machine tools in addition to make linear feed along the X, Y, Z three coordinate axes, often also need a circumferential feed movement around Y or Z axis. Circular feed motion of CNC machine tools in general by the rotary table to realize, for machining center, rotary table has become an indispensable part of.
Rotary table of commonly used CNC machine tools in the indexing table and NC rotary table.
(1) indexing table
Indexing table can only finish dividing movement, not circular feed, it is in accordance with the instructions in the NC system, when indexing will work together with the workpiece rotation angle. When indexing can also use manual indexing. Provisions of indexing table is generally only rotary angle (such as 90, 60 and 45 degree).
(2) NC rotary table
NC rotary table appearance similar to the indexing table, but the internal structure and function is not the same. The main function of the NC rotary table is based on the numerical control device sends command pulse signal, complete circumferential feed movement, various arc processing and surface processing, it can also be graduation work.
3, guide
Rail is an important part of feed drive system, is one of the basic elements of the structure of machine tool, rigidity, precision and accuracy of NC machine tool which determines to a large extent retention. At present, guide the NC machine tool are sliding rail, rolling guideway and hydrostatic guideway.
(1) sliding guide
Sliding guide rail has the advantages of simple structure, easy manufacture, good stiffness, vibration resistance and high performance, widely used in CNC machine tools, the use of most metal plastic form, known as the plastic guide rail, as shown in figure 1-26.
On characteristics of the plastic sliding guide: friction characteristic is good, good wear resistance, stable movement, good manufacturability, low speed.
(2) rolling guide
Rolling guide is placed in the rail surface between the ball, roller or needle roller, roller, the rolling friction instead of sliding surface of the guide rail between wipe.
Rolling guide rail and the sliding rail, high sensitivity, small friction coefficient, and the dynamic, static friction coefficient is very small, so the motion is uniform, especially in the low speed movement, the stick-slip phenomenon is not easy to occur; high positioning accuracy, repeatability positioning accuracy is up to 0.2 μ m; traction force is small, wear small, portable in movement; good precision, long service life. But the vibration of rolling guide, high requirements on protection, complicated structure, difficult manufacture, high cost
Automatic tool changer:
One, the function of automatic tool changer
Automatic tool changing device can help save the auxiliary time of CNC machine tools, and meet in an installation completed procedure, step processing requirements.
Two, on the requirement of automatic tool changer
Numerical control machine tool for automatic tool changer requirement is: tool change quickly, time is short, high repetitive positioning accuracy, tool storage capacity is sufficient, small occupation space, stable and reliable work.
Three, change the knife form
1, rotary cutter replacement
Its structure is similar to the ordinary lathe turret saddle, according to the processing of different objects can be designed into square or six angle form, consists of the NC system sends out the instruction to the rotary cutter.
2, the replacement of the spindle head tool change
The spindle head pre-loaded required tools, in order to machining position, the main motor is switched on, drives the cutter to rotate. The advantage of this method is that eliminates the need for automatic clamping, cutting tool, clamping and cutting tool moving and a series of complex operation, reduce tool change time, improve the reliability of the tool change.
3, the use of changing tool
The processing required tools are respectively arranged in the standard tool, adjust the size of the machine after certain way add to the knife, the exchange device from the knife and the spindle take knife switch.
Four, the tool switching device
Automatic tool change device, device for knife library and the main shaft transmission and handling tool for tool exchange device. Tool exchange often have two kinds: mechanical hand tool exchange and by relative motion of knife and machine tool spindle exchange tool (cutter to the spindle tool change or movement of the spindle to the knife knife tool change position), the mechanical hand tool change is most common.
Five, the knife
The knife is one of the most important parts in automatic tool changer, have great influence on the overall design of NC machine tool and its capacity, layout and structure.
1, the capacity of the tool storage
A number of knife inventory cutters, generally depending on the processing requirements. The capacity of small knife, can not meet the processing needs; capacity is too large, will make the knife database size, covers an area of large, tool selection process for a long time, and the knife library utilization rate is low, the structure is too complex, causing great waste.
2, the knife type
Generally, the chain disc and drum type knife several.
Disc cutter tool was circular arrangement, low utilization of space, size is not large but simple structure.
Chain magazine compact structure, large capacity, link shape can also be random bed made of various forms and flexible layout, but also will change the cutter location prominent for tool change, widely used.
Drum type or lattice type knife, covers an area of small, compact structure, large capacity, but cutter selection, tool movements are complicated, for centralized knife system for FMS.
3, tool selection
Often order tool selection and random selection tool two.
The order of tool selection is before processing, the processing required tools to process sequence of insert knife knife, order not wrong, processing adjust knife in order. The work piece changes, the need to reset the tool sequence, the operation is simple, and the processing tool with a workpiece can not be repeated use.
A knife is the cutting tool has its own code, optional and can be repeatedly used in processing, also do not put in the fixed knife, knife, the knife is convenient.
Technology file is the guiding file workers during processing, process scheme is reasonable, not only affect the efficiency of NC machining, and will directly affect the machining quality. Therefore, before NC programming, NC machining process follows the process of certain principles and combined with the characteristics of CNC lathe seriously and develop in detail the good parts.
In the CNC lathe processing parts, should according to the principle of dividing process concentrated, in a fixture as far as possible to complete the most or even all of the surface processing. Part positioning, according to the structure of different shapes, usually cylindrical, face or end clamping, and strive to design basis, process reference and programming the unification datum.
The main contents are: analysis of NC machining technology of part drawings, clear processing content; determination method, workpiece on lathe the surface processing sequence and tool feed line and cutting tools, fixtures and cutting the amount of choice.
Analysis, part drawing process
In the machining process planning of parts, first of all to carry on in-depth analysis to the processing object. For NC turning process should consider the following aspects:
1 reading part drawing, analysis of geometric conditions of part contour
In turning process of manual programming, to calculate each node coordinates; in automatic programming, to define the components outline all geometric elements. Therefore, in the analysis of parts should pay attention to:
Parts of the map is missing a dimension, the geometric conditions are not sufficient to constitute the part outline, influence;
Map location map parts of the ambiguity or dimension is not clear, so that the program can't start;
The part drawing geometry given is not reasonable, resulting in mathematical difficulties.
The part drawing dimensioning methods should adapt to the characteristics of CNC lathe processing, should size or directly given coordinate dimension with the same standard.
2 dimensional accuracy requirements
Analysis of the pattern of parts size precision requirements, to determine whether achieve the turning process, and determine the process method to control the dimension precision. In the analysis process, but also can convert some dimensions such as size, incremental and absolute size and dimension chain calculation. In the use of NC lathe turning parts, average value of components often required size and maximum and minimum limit of size size as the basis of programming.
3 shape and position accuracy requirements
Pattern of parts tolerance of shape and lo
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