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中國地質(zhì)大學(xué)長城學(xué)院
本科畢業(yè)設(shè)計外文資料翻譯
系 別： 工程技術(shù)系
專 業(yè)： 機(jī)械設(shè)計制造及其自動化
姓 名： 王嘉顯
學(xué) 號： 05208311
2011 年 12 月 18 日
外文資料翻譯譯文
五軸磨床加工工具運(yùn)動鏈的設(shè)計和分析
E.L.J. Bohez，設(shè)計與制造工程部門，亞洲技術(shù)研究所
摘 要
五軸CNC加工中心現(xiàn)在應(yīng)用得非常廣泛。大多數(shù)機(jī)器的運(yùn)動學(xué)原理都是以直角笛卡兒坐標(biāo)系統(tǒng)為基礎(chǔ)的。這篇文章對有可能的概念上的設(shè)計和基于理論上有可能的自由度的結(jié)合并且真實存在的器械進(jìn)行了分類。本文還定義了一些有用的定量參數(shù)，例如：工作空間利用因素、機(jī)器加工工具的空間利用率、方位空間的指標(biāo)和方位角。同時還分析了不同概念的優(yōu)缺點(diǎn)，給出了選擇的標(biāo)準(zhǔn)和機(jī)器結(jié)構(gòu)的設(shè)計。最近在工業(yè)中提出的一些基于斯圖爾特平臺的概念也將在這篇文章中進(jìn)行簡要的論述。
關(guān)鍵詞：五軸；機(jī)器加工工具；運(yùn)動鏈；工作空間；CNC；旋轉(zhuǎn)軸
1.介紹
機(jī)器加工工具的主要設(shè)計規(guī)范應(yīng)該滿足以下法則：
1） 運(yùn)動件在工具和零件的定位和安置上應(yīng)該
有足夠的彈性。
2） 以可能的最快的速度進(jìn)行定位和安置。
3） 以可能的最高的精確度進(jìn)行定位和安置。
4） 加工工具和工件的快速切換。
5） 保護(hù)環(huán)境。
6） 可能的高速材料移動率。
一臺機(jī)器的加工工具的軸的個數(shù)通常是由機(jī)器自由度數(shù)或者是在機(jī)器滑動過程中獨(dú)立可控的運(yùn)動數(shù)來決定的。隨著加工工具軸對應(yīng)Z坐標(biāo)軸的產(chǎn)生，ISO軸命名法推薦使用右手坐標(biāo)法則。一個三軸磨床有三個方向的線性滑動：X、Y和Z，這使得機(jī)器能放置在相應(yīng)軸向滑動范圍內(nèi)的任何一個位置。加工工具軸的方向在加工的時候保持不變。這就限制了與工件連接的加工工具的彈性，并最終導(dǎo)致很多不同的結(jié)構(gòu)。為了增加在可能的加工工具、工件定位中的彈性而不用重新設(shè)計結(jié)構(gòu)，我們將要在增加更多的機(jī)器的自由度。對于一個傳統(tǒng)的三線性軸機(jī)器，能通過提供旋轉(zhuǎn)滑動來實現(xiàn)。圖1就展示了一個五軸磨床的例子。
2.運(yùn)動鏈接圖
制作一個機(jī)器的運(yùn)動鏈接圖對于分析機(jī)器是很有用的。從運(yùn)動鏈接圖中我們可以很快區(qū)別兩組軸：圖2展示了在圖1中五軸磨床的運(yùn)動鏈接圖。從圖中我們可以看到，工件由四根軸運(yùn)載，而加工工具只由一根軸運(yùn)載。
五軸機(jī)器就像兩個相互協(xié)作的機(jī)器人，一個機(jī)器人運(yùn)載工件，另一個機(jī)器人則運(yùn)載加工工具。
為了得到工件和工具定位上最大的彈性，機(jī)器至少需要5個自由度，這意味著工具和工件能在任何角度下連接起來。從一個剛性的物體運(yùn)動連接點(diǎn)的觀點(diǎn)來說，我們也可以理解對軸的個數(shù)的最低要求。為了定位兩個在空間上相互連接的剛體，每個剛體（工具和工件）需要6個自由度或者12個自由度。然而，任何不改變兩者之間定位的共同的平移和旋轉(zhuǎn)的存在將會使自由度數(shù)目減少6個。兩個剛體之間的距離是由工具的加工路徑來決定的，這個距離也將會允許減少一個多余自由度，這樣就使得最小的自由度數(shù)為5。
3.五軸機(jī)器運(yùn)動結(jié)構(gòu)的分類
按照機(jī)器的旋轉(zhuǎn)和平移軸分類，我們可以把機(jī)器運(yùn)動結(jié)構(gòu)分為四大類：（1）三個平移軸和兩個旋轉(zhuǎn)軸；（2）兩個平移軸和三個旋轉(zhuǎn)軸；（3）一個平移軸和四個旋轉(zhuǎn)軸；（4）五個旋轉(zhuǎn)軸。近乎所有存在的五軸機(jī)器設(shè)備都屬于（1）類。很多的定位焊接機(jī)器人、圈絲機(jī)器和激光加工中心也屬于這一類。只有有限的一些用來加工輪船推進(jìn)器的五軸機(jī)器屬于（2）類。（3）和（4）類只有在設(shè)計需要增加更多自由度的機(jī)器人的時候才會用到。
五根軸可以分布在工具和工件之間的結(jié)合處。第一種分類是根據(jù)運(yùn)載軸的工具和工件的數(shù)量和在運(yùn)動鏈中各個軸的次序來劃分的。另一種分類是根據(jù)旋轉(zhuǎn)軸放置的位置（是在工具那邊還是在工件那邊）來劃分的?；诘芽▋鹤鴺?biāo)的機(jī)器中的五個自由度是：三個平移運(yùn)動X、Y、Z（一般表示為TTT）和兩個旋轉(zhuǎn)運(yùn)動AB、AC、BC（一般表示為RR）。三個旋轉(zhuǎn)軸（RRR）和兩個直線運(yùn)動軸（TT）的結(jié)合是很少見的。如果一根軸承載著工件，習(xí)慣上是用一個附加的標(biāo)記來注釋它。圖1中的機(jī)器能以X’Y’A’B’Z。XYAB軸運(yùn)載著工件，Z軸運(yùn)載著工具。圖3中展示的是XYZA’B’，三根直線運(yùn)動軸運(yùn)載工具,兩根旋轉(zhuǎn)軸運(yùn)載著工件。
3.1基于工件和工具運(yùn)載軸次序的分類
理論上，如果認(rèn)為在工具和工件運(yùn)載軸的兩個運(yùn)動鏈上的軸的次序有不同的結(jié)構(gòu)，可能的結(jié)構(gòu)的數(shù)目會非常大。同時只有兩根直線運(yùn)動軸和三根旋轉(zhuǎn)軸結(jié)合也包括在內(nèi)。
在一個五軸機(jī)器中能以以下方式將一根工具運(yùn)載軸和四根工件運(yùn)載軸結(jié)合：對于X，Y，Z，A，B，C中任意一個可能作為工具運(yùn)載的軸，其他工件運(yùn)載軸可以在剩下的五根軸中選取。所以，對于任意可能的工具運(yùn)載軸選擇（六選一或者有六種可能），在剩下的五根軸中選取四根進(jìn)行不同結(jié)構(gòu)的排列個數(shù)為5*4！=120。所以，理論上只有一根工具運(yùn)載軸的五軸機(jī)器就有6*120=720種可能。其他的結(jié)合方式也可以用這種方法分析。假設(shè)t代表工具運(yùn)載軸的數(shù)目，w表示工件運(yùn)載軸的數(shù)目（w+t=5），那么全部可能的結(jié)合數(shù)如下所示：
這個方程式的值恒等于6！或者當(dāng)w+t=5時這個值等于720。在這些720的結(jié)合中，有一些只包含兩根直線運(yùn)動軸。如果只考慮有三根直線運(yùn)動軸的五軸機(jī)器，只有3*5！=360的結(jié)合也是仍是有可能的。這些結(jié)合的預(yù)設(shè)值Gt主要是由t的預(yù)設(shè)值決定的。這個預(yù)設(shè)值和由w的預(yù)設(shè)值所決定的G`w 的預(yù)設(shè)值是一致的，其中w=5-t。運(yùn)用以上的定義，我們可以把五軸機(jī)器分為以下小群：（1）G0/G`5組；（2）G1/G`4組；（3）G2/G`3組；（4）G3/G`2組；（5）G4/G`1組；（6）G5/G`0組。
3.2基于旋轉(zhuǎn)軸的位置的分類
我們能根據(jù)旋轉(zhuǎn)軸裝配的位置對機(jī)器進(jìn)行分類。
只有那些有兩根旋轉(zhuǎn)軸和三根線性軸的機(jī)器我們才會進(jìn)一步考慮?？赡艿慕Y(jié)構(gòu)如下：
（a）旋轉(zhuǎn)軸裝配在工具桿上；
（b）旋轉(zhuǎn)軸裝配在機(jī)器平臺；
（c）兩者的結(jié)合。
如果機(jī)器的軸的R或者T的類型一樣，那么在工具或者工件運(yùn)載運(yùn)動鏈中軸的次序就不重要了。一般來說，如果在工件運(yùn)載運(yùn)動鏈中有根平移軸和根旋轉(zhuǎn)軸，在工具運(yùn)動鏈中有根平移軸和根旋轉(zhuǎn)軸，那么結(jié)合的個數(shù)為[11]：
其中
每一組的結(jié)合的個數(shù)在下面中將會一個個給出。所有組的結(jié)合總數(shù)為60。從設(shè)計的觀點(diǎn)來說，這是我們所考慮的選擇的數(shù)量中較為容易處理的一個。
4.五軸機(jī)器的工作空間
在定義五軸機(jī)器設(shè)備的工作空間之前，要適當(dāng)?shù)亩x加工工具的工作空間和工件的工作空間。加工工具的工作空間就是通過沿著工具運(yùn)載軸路線描繪出工具掃過參考點(diǎn)（例如工具尖端）而得到的。工件運(yùn)載軸的工作空間也是用同樣方法定義的（把機(jī)器平臺的中心選擇作為參考點(diǎn)）。這些工作空間能由計算掃過過的體積決定[6]。
基于以上的定義，我們能定義一些對于不同類型機(jī)器比較、選擇和設(shè)計有用的定量參數(shù)。
4.1.工作空間利用因素
這個因素可以定義為，工件空間和工具空間的交集與工具空間和工件空間的并集的比。公式為
4.2.可加工的體積大小
一旦工件相對于工件參考點(diǎn)是固定的，并且一個特殊的工具相對于工具參考點(diǎn)也是固定的，那么我們就有可能確定可加工的體積的大小?？杉庸さ捏w積就是能夠在工件上切除的全部體積。機(jī)器工具空間和工件的交集給出了可以切除的材料的總量，或者說是可加工的體積（這是對于特殊的工件和工具機(jī)構(gòu)來說的）。
4.3.機(jī)器工具空間效率
機(jī)器工具空間效率的定義為：機(jī)器工具空間（省略了一部分）和包含著機(jī)器的最小凸起體積。
4.4.五軸機(jī)器的定位空間指數(shù)
一個我們用來估計定位的最大范圍的方法是為了決定能在機(jī)器上用兩根旋轉(zhuǎn)軸加工的球的最大部分?？臻g定位指數(shù)定義為能夠由用所有旋轉(zhuǎn)軸加工的機(jī)器來加工的最大的球頂體積除以機(jī)器工具空間。
如果這個指數(shù)趨近于1，這就意味著所有的旋轉(zhuǎn)軸能夠在整個機(jī)器工具空間中運(yùn)用。如果這個指數(shù)比1小，這就意味著大概百分之的工作空間能運(yùn)用所有的旋轉(zhuǎn)軸。
以上的定義都是理論上的定義。實際上的定位空間指數(shù)會因為避免零件和機(jī)器、工具和工件之間的碰撞而進(jìn)一步受到限制。能夠加工的球頂變小就說明了這一點(diǎn)。
5.五軸機(jī)器的選擇標(biāo)準(zhǔn)
我們的目的不是對五軸機(jī)器對于某一項特定的運(yùn)用的選擇或者設(shè)計進(jìn)行一個徹底的研究。我們只是論述能用來判斷五軸機(jī)器的選擇的主要的標(biāo)準(zhǔn)。
5.1.五軸機(jī)器設(shè)備的應(yīng)用
應(yīng)用能在布置和造型上進(jìn)行區(qū)分。圖12和圖13說明了五軸的布置和五軸造型上的區(qū)別。
5.1.1.五軸布置
如圖12所示，一個在不同角度有著很多孔和平面板的零件，僅僅用一臺三軸磨床來加工這個零件是不可能的。如果我們在用一臺五軸機(jī)器，那么工具能在任何方向和工件定位連接起來。一旦達(dá)到了正確的位置，在大多數(shù)軸固定的情況下，我們就可以對孔和平面板進(jìn)行加工了。平面板中能包括獨(dú)立結(jié)構(gòu)的2D平面。如果我們僅僅是要鉆孔，那么理論上一軸CNC同步控制就足夠了，而加工2D平面時兩軸同步控制就夠了。然而，三軸同步現(xiàn)在也很普遍了。當(dāng)我們把工件和工具放置在連接在一起的時候，這就增加了在開始切削前的快進(jìn)的速度。
5.1.2.五軸造型
圖13所示為一個五軸造型的例子，為了加工這個形狀復(fù)雜的表面，我們需要在切削時控制好與零件接觸的刀具的位置。刀具工件的位置在每一步工序中都會改變。CNC控制器需要在材料切除過程中同步控制五軸。更多關(guān)于造型的細(xì)節(jié)能在參考文獻(xiàn)[13]中找到。五軸的機(jī)器有如下的應(yīng)用：（1）生產(chǎn)刀刃，如： 壓縮機(jī)和渦輪的漿；（2）燃料泵的注射器；（3）頭飾的外形；（4）醫(yī)學(xué)器官例如人造心臟閥；（5）復(fù)雜表面的鑄型。
5.2.軸結(jié)構(gòu)的選擇
在設(shè)計和選擇一個結(jié)構(gòu)時，零件的尺寸和重量是首要的標(biāo)準(zhǔn)。重型工件要求工件運(yùn)動鏈短。同時，水平加工平面又是較好的一種設(shè)計，這種設(shè)計會使定位和處理工件變得很便利。把一個重型工件放在一個單獨(dú)旋轉(zhuǎn)軸運(yùn)動鏈上將會很大程度上增加定位的彈性。從圖4中我們可以看出，用一個單獨(dú)水平旋轉(zhuǎn)軸來運(yùn)載工件會使得機(jī)器更加具有彈性。
在很多情況下，我們應(yīng)該把工具運(yùn)動鏈保持得盡量短，因為我們還必須運(yùn)載工具軸驅(qū)動裝置。
6.結(jié)論
理論上，五軸機(jī)器有很多構(gòu)成方式。近乎所有經(jīng)典的笛卡兒坐標(biāo)五軸機(jī)器都屬于由三根線性軸和兩根旋轉(zhuǎn)軸，或者三根旋轉(zhuǎn)軸和兩根線性軸組成的系列。這個系列又可以細(xì)分為有著720種情況的六組。就算只考慮三根線性軸的情況，在每個系列中仍然有360種組合。這些不同的組合是根據(jù)在工具和工件運(yùn)載運(yùn)動鏈中軸的次序來區(qū)分的。
如果在對由三根線性軸和兩根旋轉(zhuǎn)軸組成的五軸機(jī)械進(jìn)行分組時，只考慮在工具和工件運(yùn)動鏈中旋轉(zhuǎn)軸的位置，那么我們能五軸機(jī)器分為三組。在第一組中，兩根旋轉(zhuǎn)軸安置在工件運(yùn)動鏈。在第二組中，兩根旋轉(zhuǎn)軸安置在工具運(yùn)動鏈。在第三組中，每個運(yùn)動鏈都安置一根旋轉(zhuǎn)軸。每一組仍然有20種可能的情況。對于一個特定的應(yīng)用領(lǐng)域，要從這些組合中選出一組最好的是一項很復(fù)雜的工作。為了使這項工作變得容易些，我們定義了一些用于比較的指數(shù)，例如：機(jī)器刀具空間、空間利用因素、定位空間指數(shù)、定位角度指數(shù)和機(jī)器刀具空間效率。列出了用來計算機(jī)器刀具空間和在機(jī)器上能加工的最大球頂?shù)闹睆降乃惴?。詳?xì)論述了兩個運(yùn)用這些指數(shù)的例子。第一個例子論述的是加工珠寶的五軸機(jī)器的設(shè)計。第二個例子則闡明了一臺機(jī)器在線性軸中有著相同范圍，在這種情況下，旋轉(zhuǎn)軸選項的選擇（略）。
運(yùn)用得最廣泛的五軸機(jī)器的兩根旋轉(zhuǎn)軸安置在運(yùn)動鏈末端處的工件一側(cè)。這種結(jié)構(gòu)給出了一種對于機(jī)器刀具結(jié)構(gòu)的模塊設(shè)計。然而，從應(yīng)用的觀點(diǎn)來說，這種模塊設(shè)計并不總是最理想的。因為理論上存在很多可能的結(jié)構(gòu)，很明顯的是，對于一個特殊的工件裝置需要一個合適的特定的五軸機(jī)器。模塊設(shè)計應(yīng)該以在所有的五軸結(jié)合中的模塊性為基礎(chǔ)。當(dāng)前在設(shè)計中的模塊性是以三線性軸機(jī)器為基礎(chǔ)的。
五軸磨床使得機(jī)器結(jié)構(gòu)的數(shù)量變小。這對增加精確度和減小大部分尺寸是有幫助的。然而，它也有一些缺點(diǎn)：（1）五軸機(jī)器的高價；（2）增加的旋轉(zhuǎn)軸的同時也增加了定位誤差；（3）在同等的進(jìn)給下，在機(jī)器軸上的切削速度更高。
在購買五軸機(jī)器之前必須要對需要加工的產(chǎn)品的范圍進(jìn)行深入的研究。那些零件也應(yīng)該分為五軸定位或者是五軸造型，或者兩者都是。例如，有著旋轉(zhuǎn)平臺的機(jī)器對于生產(chǎn)諸如壓縮機(jī)的旋轉(zhuǎn)工件是很好的。一根旋轉(zhuǎn)軸在刀具側(cè)，一根旋轉(zhuǎn)軸在工件側(cè)，這樣的布置將會提供更大的工作空間利用因素。
最近所介紹的虛擬軸機(jī)器有著一個主要的優(yōu)點(diǎn)：潛在的更高的動力響應(yīng)和更高的硬度。然而，它的工作空間利用因素比經(jīng)典的五軸機(jī)器要低。這些機(jī)器的更高強(qiáng)度使得他們非常適于高速磨所需要的高速桿[19]的設(shè)計。
外文原文
Five axis grinding machining tools sports chain design and analysis
Abstract: five axis CNC processing center now very widely applied in most machine of the kinematic theory is right Angle Descartes coordinate system is the basis of this article to likely conceptual designs and based on the theory of the combination of may have freedom and real devices are classified this paper also define some useful quantitative parameters, such as: work space use machine tools factors space utilization orientation of the space index and azimuth and analyzes the advantages and disadvantages of different concepts are given, and the standard of the choice and machine structure design in industry recently proposed some based on the concept of Stewart platform will also in this article briefly discussed.
Keywords: five axis; Machine tools; Sports chain; Working space; CNC; axis
1. Introduction
The main machine tool design code should meet the following rules:
1) moving parts in the tool and parts localization and placed it should be
Have enough flexibility.
2) may be the fastest speed positioning and placement.
3) the accuracy of the highest possible location and placement.
4) processing tools and workpieces quickly switch.
5) to protect the environment.
6) possible high-speed materials mobile rate.
A machine processing tools of the number of shaft is usually free degree or by machine is in the machine in the process of independent controllable sliding movement to the number of decision. Along with the machining tools shaft corresponding Z coordinate transformation of produce, ISO shaft nomenclature recommend using the right hand coordinate law. A three axis grinding machine has three of the direction of linear slide: X, Y and Z, which make the machine should be placed in the corresponding axial sliding range of any one place. The direction of the axis machining tools in processing remain unchanged. This limits the workpiece machining tools of connection with the flexibility, and eventually lead to a lot of different structure. In order to increase the processing tools in May, workpiece position of elastic and need not to design structure, we are going to add more machine of freedom. For a traditional three linear axis machine, can provide rotation to realize by sliding. Figure 1 shows a five axis grinding machine example.
2. Sports link figure
Make a machine for the movement of the link chart analysis machine is very useful. Links from sports graph, we can quickly difference between two groups of shaft: figure 2 shows in figure 1 5 axis grinding machine movement link figure. We can see from the graph, the four shaft by carrier, and only by machining tools to carry a shaft.
Five axis machine like two cooperation robot, a robot carrying workpiece, the other a robot is carrying machining tools.
In order to get the workpiece and tools on the elasticity of the largest position, the machine will need at least five degrees of freedom, this means that the tool and workpiece can connect all the way down. From a rigid motion connection point point of view, we can also understand the number of shaft of the minimum requirements. In order to positioning two in space connected rigid body, each rigid body (tool and workpiece) need six degrees of freedom or 12 degrees of freedom. However, any not change the location of the common between translation and rotation of the existence of freedom will make cutting the number six. The distance between the two rigid bodies is the tools to the processing route, this distance will also allow reduce a redundant freedom, this make the smallest degree freedom for five.
3、Five axis machine movement structure of the classification
According to the rotation of the machine moving axis peace classification, we can get the machine movement structure are divided into four categories: (1) three translation axis and two axis; (2) two translation axis and three axis; (3) a translation axis and four axis; (4) five axis of revolution. Almost all existing five axis machine equipment belong to (1) type. A lot of positioning welding robot, silk machine and laser processing center also belong to this category. Only limited some used to ship propulsion five axis of processing machine belong to (2) class. (3) and (4) class only in design needs to increase more degrees of freedom when the robot will be used.
Five shaft can be spread in the tool and workpiece department between. The first kind of classification is carrying the shaft according to the number of tool and workpiece and in sports in the order of the chain of each axis to differentiate. Another classification is placed on the axis of the position (is there or in the workpiece in tool there) to differentiate. Based on Descartes coordinates of machine five of the degree of freedom is: three translation movement X, Y, Z (usually expressed as TTT) and two rotation movement AB, AC, BC (usually expressed as RR). Three degrees of rotation (RRR) and two linear motion axes (TT) is a rare combination of. If a root bearing carrying workpiece, the custom is with an additional signs to note it. The machine in figure 1 to X "Y 'A' B 'Z. XYAB axis is carrying the Z axis is carrying tools. Figure 3 shows XYZA "B", three straight line moving axis vehicles, carrying two of the axis of the workpiece.
3.1 the workpiece and tools based on the classification of the carrier shaft order
In theory, if think tool and workpiece axis in carrying the two movement on the order of the chain of shaft have different structure, the number of possible structure will be very big. And only two straight line moving axis and three root the axis of the combination is also included.
In A five axis machine in the following way can put A tool carrier axis and the four pillars carry axial workpiece with: for X, Y, Z, A, B, and C at any of the shaft may be as A tool to carry, other workpiece axis can carry in the remaining five selected from the shaft. So, for any possible tool carrier shaft choice (six choose a or are six may), in the rest of the five shaft from the four pillars of different structure arrangement for 5 * number 4! = 120. So, in theory only a piece of the five shaft carrying tool axis machine will have six * 120 = 720 possible. The combination of the other way also can use this method analysis. Assumption t represent tool carrier to the number of the shaft, w said the number of carrying the axis (w + t = 5), so all the possible combination number shown below:
The value of this equation in identical 6! Or when w + t = 5 when the value is equal to 720. In the combination of these 720, some contain only two straight line moving axis. If only consider three straight line moving axis five axis machine, only 3 x 5! The combination of = 360 also is still possible. The combination of the default value Gt is mainly composed of t the default value of the decision. The default value and the default value by w determined G ` w the default value is consistent, including w = 5-t. Using the above definition, we can put the five axis machine divided into the following a small group of: (1) G0 / G ` 5 groups; (2) the G1 / G ` 4 groups; (3) the G2 / G ` 3 groups; (4) G3 / G ` 2 groups; (5) G4 / G ` 1 group; (6) G5 / G ` 0 group.
3.2 Based on the classification of the axis of the position
We can on the axis of the position of the assembly of the machine are classified.
Only those who have the two root and the axis of the three pillars of the linear axis machine we will further consideration. The structure of the may be as follows:
(a) the axis of the assembly in the tool pole;
(b) the axis of the assembly in machine platform;
(c) the combination of both.
If the machine of shaft or the type of T R, so in the tool carrier movement or the axis of the order of the chain is not important. Generally speaking, if the carrier movement in the chain with roots translation axis and the axis of the root, the tools of kinematic chains root translation axis and the axis of the root, so the number of combination for [11] :
Among them
Each of the combination of the number below will give one. All set for the total number of combinations of the 60. From a design point of view, this is what we consider the number of choice in to deal with a relatively easy.
4. Five axis machine work space
Five axis machine equipment in the definition of the work before space, to the proper definition machining tools work space and the work space. Machining tools work space is along the tool carrier axis line through paint tools swept reference points (such as tool tips) and get. The carrier of shaft space also is working with the same methods defined (the center of the machine platform choice as a reference point). These work space can have the volume by calculating and decision [6].
Based on the above definition, we can define some for different types of machine more, selection and design of useful quantitative parameters.
4.1. Work space using factor
This factor can be defined as the work space and tools of the space with tools with space and the space and set than. Formula for
4.2. Can be processed to the volume of the size
Once the relative to the workpiece reference point is fixed, and a special tool relative to tool reference point is fixed, so we probably can determine the size of the processing. But the volume of processing is to the all the volume resection. The machine tool and workpiece with space of given the amount of material can be removed, or is it can be processed to volume (this is the special workpiece and tools for institutions).
4.3. Machine tools space efficiency
The machine tool is the definition of "efficiency of space for: machine tools space (omitted part) and contains the minimum volume machine raised
4.4. Five axis machine positioning space index
A we used to estimate the positioning of the maximum range of method is to determine in the machine with two of the processing of the axis of the ball the most. Space positioning index is defined as can use all of the processing by axis machine to the biggest ball processing top volume divided by machine tools space.
If the index is approaching to 1, this means that all the axis in the whole machine tool can be used in space. If the index greater than 1 small, that means about of working space can use all the axis of revolution.
The above definition is theoretical definition. In fact the positioning of the space index will avoid components and machine, because the collision between tool and workpiece and further limited. Can the header smaller processing is showed this point.
5. Five axis machine selection criteria
Our purpose is not to the five axis machine to one a specific use of choice or design for a thorough research. We just discussed five axis machine can be used to judge the choice of the main criteria.
5.1. Five axis machine equipment used
Application in decorate on modelling and can distinguish. Figure 12 and figure 13 shows the five axis decorate and five axis modelling difference.
5.1.1. Five axis layout
As shown in figure 12 shows, a different Angle in a very porous peace panel parts, with only a three axis grinding machine to processing the parts is impossible. If we use a five axis machine, so tools can in any direction and workpiece positioning joined up. Once reached the correct position,
In the most fixed a number line, we can carry on the processing of hole peace panel. Graphic board can include independence structure of 2 D plane. If we merely to drilling, so in theory a axis CNC synchronous control is enough, and processing 2 D plane two-axle synchronous control is enough. However, three axis synchronous now also very popular. When we put the workpiece and tools placed in together, this increases the start before cutting in the speed of fast forward.
5.1.2. Five axis modelling
Figure 13 shows is a 5 axis of modelling example, in order to processing the complex shape of the surface, we need to be in control when the cutting tool parts contact with good position. The position of the tool workpiece in every step process will change. CNC controller needs in the material removal process of synchronous control five axis. More about the details of the modelling in reference [13] find. Five axis machine has the following: (1) the application of blade production, such as: the compressor and turbine blades; (2) the fuel pump injector; (3) tire appearance; (4) medical organs such as artificial heart valve; (5) complex surface of the casting.
5.2. The choice of shaft structure
In the design and choose a structure, part size and weight is the first standard. Heavy workpiece requirements workpiece sports chain short. At the same time, the plane is a good level processing a design, the design can make positioning and processing workpiece become very convenient. Put a heavy work in a single axis motion chain will greatly increase the elasticity of the positioning. In figure 4 we can see that, with a single level to carry workpiece axis will make the machine more flexible.
In many cases, we should put the tool to keep sports chain short, because we must also the vehicle shaft drive device.
6. Conclusion
In theory, the five axis machine has many structure mode. Almost all the classic Descartes coordinates five axis machines are belong to by three root linear axis and the axis of the two root, and two or three root the axis of the root of linear axis of the series. This series can be divided into 720 and has a sort of six group. Even if only consider three pillars of linear axis, and in every series 360 is still kind of combination. These different combinations is according to the tool and workpiece axis of the chain carrying movement order distinguish.
If in the three pillars of linear axis and the two root of the axis of the five shaft machinery group, considering only in the tool and workpiece movement in the position of the axis of the chain, then we can five axis machine into three groups. In one group, the two root placed on the axis of the workpiece sports chain. In the second group, the two root placed in tool axis motion chain. In the third group, each movement chains find a place for the root the axis of revolution. Each group still have 20 May. For a particular application fields, from the combination of the best choose a group is a very complicated work. In order to make the work become easier, we define some used to compare the index, for