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文 獻 綜 述
1.1課題研究背景
由于滾珠絲杠副獨特的優(yōu)良技術(shù)性能,其研究迅速得到了世界許多國家的高度重視,滾珠絲杠傳動的應(yīng)用也隨之?dāng)U展到其它領(lǐng)域中。隨著機床自動化的發(fā)展,特別是1965年數(shù)控機床的出現(xiàn),促進了滾珠絲杠副產(chǎn)品的品種和規(guī)格的發(fā)展。質(zhì)量和產(chǎn)量的提高,推動了設(shè)計技術(shù)和制造工藝的進步,迅速研制了加工和磨削滾珠螺母的專用機床。隨著新工藝的發(fā)展,制造技術(shù)的進步,大幅度的提高了滾珠絲杠副的生產(chǎn)效率和質(zhì)量,同時縮短了生產(chǎn)的周期,降低了成本,反過來又促進了滾珠絲杠副品種和規(guī)格的擴大、質(zhì)量和產(chǎn)量的進一步提高、系列化等方面的重大發(fā)展。
早在19世紀末就發(fā)明了滾珠絲杠副,但很長一段時間未能實際應(yīng)用,因制造難度太大。世界上第一個使用滾珠絲杠副的是美國通用汽車公司薩吉諾分廠,它將滾珠絲杠副用于汽車的轉(zhuǎn)向機構(gòu)上。
由于設(shè)計制造等技術(shù)的進步,滾珠絲杠副的結(jié)構(gòu)也有著一定的改進和變化,比如說日本THK公司已經(jīng)將帶有保持架的滾珠絲杠副產(chǎn)品化,其產(chǎn)品的綜合性能得到了很大的提高。隨著機械產(chǎn)品向高速、高效、自動化方向發(fā)展,工業(yè)機器人、數(shù)控鍛壓機械、加工中心以及機電一體化自動機械等,其進給驅(qū)動速度不斷提高,大導(dǎo)程滾珠絲杠副的出現(xiàn),滿足了高速化的要求。日本NSK公司已開發(fā)出公稱直徑×導(dǎo)程為:15mm×40mm、16mm×50mm、20mm×60mm、25mm× 80mm超大導(dǎo)程滾珠絲杠副,快速進給速度達180m/min。從前,擔(dān)心大導(dǎo)程滾珠絲杠副驅(qū)動對加工中心精度的影響,設(shè)計時取導(dǎo)程Ph≤10mm。隨著科學(xué)技術(shù)的進步,從1999年日本國際機床展覽會上可看出,設(shè)計與研究現(xiàn)在大部分高速加工中心都使用大導(dǎo)程滾珠絲杠副[4]。
1.2課題研究的意義
1.2.1滾珠絲杠的優(yōu)點
它是一種新的滾動摩擦傳動機構(gòu),與滑動絲杠螺母機構(gòu)相比具有以下特點:
1.傳動效率高,摩擦損失小 滾珠絲杠螺母傳動效率92%~96% ,比滑動絲杠螺母的20%~40%提高2~4倍,而消耗的功率僅為滑動絲杠螺母的1/4~1/3
2.動作靈敏無爬行現(xiàn)象 滾動摩擦的啟動阻力很?。◣缀跖c運動速度完全無關(guān)),運動平穩(wěn)、動作靈敏,在低速下能均勻運動且不易出現(xiàn)爬行現(xiàn)象,特別適于位移速度較低的高精度傳動。
3.精度保持性好 滾動摩擦的磨損小,壽命長在長期運轉(zhuǎn)中能保持較好的精度
4.經(jīng)適當(dāng)預(yù)緊能實現(xiàn)無間隙傳動 采用雙螺母加預(yù)緊力控制彈性變形,經(jīng)調(diào)整后能基本上消除軸向間隙,提高軸向精度,在無間隙和過盈下能正常運轉(zhuǎn),并具有較高的定位精度和位移精度。機床上采用滾珠絲杠螺母傳動,是一種精密而又省力的運動轉(zhuǎn)換裝置。
性。
1.2.2研究滾珠絲杠的實用意義
機電一體化技術(shù)是機械工業(yè)發(fā)展的必然趨勢,有廣闊的技術(shù)前景。滾珠絲桿副是為了適應(yīng)機電一體化機械傳動系統(tǒng)的要求而發(fā)展起來的一種新型傳動機構(gòu),由滾珠絲杠、滾珠螺母(組件)和滾珠組成,可以將旋轉(zhuǎn)運動變?yōu)橹本€運動,或者將直線運動轉(zhuǎn)變成旋轉(zhuǎn)運動。它具有傳動效率高、啟動力矩小、傳動靈敏平穩(wěn)、工作壽命長等優(yōu)點。但是由于制造和裝配的誤差,滾珠絲杠副總是存在間隙,同時,滾珠絲杠在軸向載荷的作用下,滾珠和螺紋滾道接觸部位會產(chǎn)生彈性變形,影響滾珠絲杠的傳動精度。
滾珠絲杠副不僅是各類數(shù)控裝備的核心功能部件,還是機械工業(yè)領(lǐng)域中資本密集型和技術(shù)密集型的重要通用零部件。在線性傳動家族中滾珠絲杠副是應(yīng)用面很廣,產(chǎn)業(yè)化程度較高的產(chǎn)品。
參考文獻:
[1] 寧立偉.滾珠絲杠副. 機床數(shù)控技術(shù),高等教育出版社.2010.1
[2] 2012滾珠絲杠副的發(fā)展報告. http://www.hqew.com ,
[3] 百度百科. 滾珠絲杠副.http://baike.baidu.com/view/3835478.htm
[4] 肖正義.滾珠絲杠副的發(fā)展趨勢.制作技術(shù)與機床.2000.04
[5] 黃祖堯.21世紀初海外滾動功能部件發(fā)展動態(tài).世界制作技術(shù)與裝備市場.2003.2
[6] 程光仁.施祖康.滾珠螺旋傳動設(shè)計基礎(chǔ).北京.機械工業(yè)出版社.1987.08
[7] 喻忠志.我國滾動功能部件產(chǎn)業(yè)現(xiàn)狀分析.制造技術(shù)與機床.2004.04
[8] 中國藝工滾動功能部件產(chǎn)品綜合樣本及資料
[9] 肖正義.焦?jié)?高速滾珠絲杠副的研發(fā)與測試技術(shù).制造技術(shù)與機床.2004。04
[10] 滾珠絲杠譯文集.南京工藝裝備廠.1980.08
畢 業(yè) 設(shè) 計 開 題 報 告
2.本課題要研究或解決的問題和擬采用的研究手段(途徑):
1.在圖書館借閱相關(guān)書籍、論文等,并進行整理。
2.在學(xué)校數(shù)據(jù)庫查找相關(guān)資料。
3.在網(wǎng)上查找相關(guān)資料。
4.對找到的資料和數(shù)據(jù)進行分析和計算。
5.整合查到的數(shù)據(jù)和資料開始寫畢業(yè)論文。
6.論文撰寫按構(gòu)思框架、編寫提綱、專題研討幾個步驟進行。在編寫過程中征求老師和同學(xué)的意見使論文內(nèi)容更加全面。
畢 業(yè) 設(shè) 計 開 題 報 告
指導(dǎo)教師意見:
對滾珠絲杠的初步認識比較明確,希望能將畢業(yè)設(shè)計做得更好。
指導(dǎo)教師:
2016年 3 月20日
所在系審查意見:同意
系主任:
2016年3月20日
滾珠絲杠副設(shè)計及相關(guān)技術(shù)研究
摘要:滾珠絲杠是因其自身良好的可靠性,精度等級高,使用及維護成本都比較低的優(yōu)勢被廣泛應(yīng)用于多種場合,其中高精密機床上應(yīng)用甚多。所以研究和優(yōu)化滾珠絲杠具有巨大的前景。本設(shè)計中具體對滾珠絲杠進行了多方面的學(xué)習(xí),包括滾珠絲杠相關(guān)各種參數(shù)的計算及其校核。并對絲杠周圍部件進行了了解。除此之外,本設(shè)計還對滾珠絲杠的高速化及其優(yōu)化方案也進行了簡述。
關(guān)鍵詞:滾珠絲杠 設(shè)計方案 高速化
II
中北大學(xué)信息商務(wù)學(xué)院2016屆畢業(yè)設(shè)計說明書
Abstract:Ball is due to its own good reliability, high level of accuracy, use, and maintenance costs are relatively high advantages are widely used in a variety of situations, many of which use high-precision machine tools. Therefore, research and optimization ball screw has great prospects. The specific design of the ball screw conducted extensive research, including the calculation of various parameters related to ball screws and check. And screw around parts of the inquiry. In addition, this design also on the high-speed ball screw and its optimization program has also been outlined.
Keywords: high-speed ball screw design
目 錄
摘要 ……………………………………………………………………………I
Abstract ……………………………………………………………………………II
目錄………………………………………………………………………………III
1.緒論 ……………………………………………………………………………1
1.1滾珠絲杠概述………………………………………………………………3
1.2本課題研究的意義…………………………………………………………8
2.滾珠絲杠的設(shè)計 ………………………………………………………………8
2.1原始數(shù)據(jù)與技術(shù)條件………………………………………………………9
2.2滾珠絲杠的主體參數(shù)設(shè)計…………………………………………………9
2.2.1導(dǎo)程的選擇 ……………………………………………………10
2.2.2 絲杠軸長度的選擇 ………………………………………………11
2.2.3絲杠軸直徑的選擇 ………………………………………………13
2.2.4絲杠軸支撐方式的選擇 …………………………………………12
2.2.5螺母的選擇 ………………………………………………………13
3.各零部件的校核………………………………………………………………14
3.1容許軸向負載的計算 ……………………………………………………14
3.2絲杠軸容許轉(zhuǎn)速的計算 …………………………………………………15
3.3螺母運行距離的計算 ……………………………………………………15
3.4螺母軸向平均負荷及其壽命校核 ………………………………………16
4.定位精度的探討……………………………………………………………18
4.1導(dǎo)程精度的探討 …………………………………………………………18
4.2軸向間隙的校核 …………………………………………………………18
4.3軸向剛性的校核 …………………………………………………………18
4.4運行姿態(tài)的探討 …………………………………………………………19
4.5旋轉(zhuǎn)扭矩的校核 …………………………………………………………19
5.電動機的選擇 …………………………………………………………………20
5.1旋轉(zhuǎn)速度 …………………………………………………………………20
5.2最小進給量 ………………………………………………………………20
5.3電動機扭矩……………………………………………………………20
5.4扭矩的有效值 ……………………………………………………………21
6.滾珠絲杠高速化研究 ………………………………………………………21
1.精密滾珠絲杠副實現(xiàn)高速化要解決的主要矛盾 …………………………21
2.滾珠絲杠副高速化的技術(shù)對策 …………………………………………22
7.總結(jié) ……………………………………………………………………23
參考文獻 ……………………………………………………………………24
致謝 …………………………………………………………………25
V
1.緒論
1.1滾珠絲杠的概述
滾珠絲桿是一種能在直線進給和周轉(zhuǎn)運動之間互相轉(zhuǎn)換的理想的機械產(chǎn)品。因具有傳動效率、運動平穩(wěn)、高精度、高耐磨性、高同步、高可靠性、無背隙和高剛性的諸多優(yōu)點,并被廣泛應(yīng)用于機械行業(yè)。
傳統(tǒng)的滾珠絲杠采用循環(huán)方式主要有三種。
第一,外循環(huán),(管路式)其結(jié)構(gòu)簡單易于使用。在滾珠滾道內(nèi)通過一根插管將進口和出口相連接,從而達到無限循環(huán)。
圖1-5外循環(huán)
第二,內(nèi)循環(huán),(哥德式)其結(jié)構(gòu)緊湊,也比較易于小型化,但制造成本較高。
圖1-6 內(nèi)循環(huán)
第三,端蓋式。(端面式)
1
圖1-7 端蓋式
滾珠絲杠至誕生以來,就得到了世人的許多關(guān)注,也進行了比較大的改進和融合。并發(fā)展出了許多不同用途,不同型號的滾珠絲杠產(chǎn)品。如在日本相關(guān)專利方面就有除了傳統(tǒng)內(nèi)外循環(huán)的滾珠絲杠外,還出現(xiàn)了不使用循環(huán)的滾珠方案,并且得到了諸多應(yīng)用。以下以舉例的形式表達一種非循環(huán)的滾珠絲杠方式:如圖,該發(fā)明滾珠絲杠螺母內(nèi)加入彈性元件,并使其能夠很方便放入滾道內(nèi),使之隨著滾珠體一起進行運動。在1-1、1-2圖中,當(dāng)滾珠體逆時針旋轉(zhuǎn)時,會壓迫彈性元件也向逆時針運動。當(dāng)該方向運動結(jié)束后,彈性元件便會將滾珠體再壓回原來位置。同理也有另外一個方向,如圖1-3所示。
2
圖1-1 一種非循環(huán)方式的滾珠絲杠裝置
循環(huán)軌道中的彈性元件能夠在運動的開始和結(jié)束狀態(tài)起到儲能的作用,也是實現(xiàn)非循環(huán)方式運動的關(guān)鍵。
3
圖1-2 一種非循環(huán)方式逆時針方向動態(tài)圖解
圖1-3 一種非循環(huán)方式順時針方向動態(tài)圖解
可以想象如此設(shè)計能夠最大限度地縮小螺母的徑向長度,從而為滾珠絲杠的小型化開辟了道路。
圖1-4 一種非循環(huán)方式滾珠絲杠三維圖例
1.2本課題研究目的
CNC數(shù)控機床中,進給系統(tǒng)的主體實現(xiàn)元件是滾珠絲杠副。雖然滾珠絲杠已經(jīng)出現(xiàn)了近百年的歷史,但其優(yōu)越性能仍然是現(xiàn)在許多元件無法替代的,并且具有很大的優(yōu)勢,啟動力矩小,定位精度高,運行可靠。并且隨著其他相關(guān)技術(shù)的成熟進步,尤其是材料性能的改善和工藝技術(shù)的改進優(yōu)化,滾珠絲杠副的優(yōu)勢將更加凸顯,所以我們很有必要將滾珠絲杠副的優(yōu)化設(shè)計放在自己的設(shè)計理念中,并將其優(yōu)點發(fā)揚光大。
2.滾珠絲杠的設(shè)計
2.1原始數(shù)據(jù)與技術(shù)條件
表1.1滾珠絲杠的主體設(shè)計要求
工作臺重量W1
25kg
工作及夾具最大重量W2
80kg
工作臺最大行程 LK
1000mm
快速進給速度Vmax
60m/min
動摩擦系數(shù)
μ=0.003
定位精度
0.02mm/300mm
重復(fù)定位精度
0.01mm
全行程定位精度
0.025mm
要求壽命
30000 h
導(dǎo)向面阻力
15N
額定轉(zhuǎn)速
3000 r/min
驅(qū)動電動機
AC伺服電機
減速器A
1
電動機的慣性扭矩
0.001
圖2-1 滾珠絲杠裝置整體受力圖
表1.2滾珠絲杠的主體參數(shù)
絲杠軸直徑
導(dǎo)程
螺母型號
精度
軸向間隙
絲杠軸支撐方式
電動機功率
2.2.1導(dǎo)程的選擇
導(dǎo)程的選擇必須與所需要的最高速度相配合,本設(shè)計中的滾珠絲杠裝置最高速度選取1m/s,也即60000mm/min。電動機擬采用AC伺服電機,其最大轉(zhuǎn)速為3000r/min。綜上,可計算出導(dǎo)程的許用最小值L為:
mm
在這里,根據(jù)機械手冊中查表數(shù)據(jù)可得滾珠絲杠的導(dǎo)程取L=20mm。
2.2.2絲杠軸長度選擇
絲杠軸的選擇必須考慮到螺母的長度,現(xiàn)在暫定其長度為160mm,絲杠軸兩末端支撐長度為160mm。
根據(jù)實際需求,絲杠長度行程長度選擇為1000mm。
則絲杠軸全長為:
2.2.3絲杠軸直徑的選擇
本設(shè)計中絲杠軸擬采用一端固定,一端支撐的方式
(公式2.1)
當(dāng)安裝方式為固定,支撐時,查表:f=15.1
則Dr21.9mm
由機械設(shè)計手冊所示滾珠絲杠型號∶
絲杠軸直徑 導(dǎo)程
20mm —— 20mm
20mm —— 40mm
30mm —— 60mm
由上所述,根據(jù)機械手冊查表最終確定絲杠軸直徑40mm/導(dǎo)程20mm的設(shè)計方案。絲杠軸的設(shè)計到此為止,總體的設(shè)計圖例見下
圖4-1絲杠軸
2.2.4軸支撐方法的選擇
本設(shè)計中滾珠絲杠的最大行程為1000mm,屬于遠跨距安裝;速度為1m/s,屬高速使用;而且考慮到升溫比較有可能會導(dǎo)致絲杠軸變形彎曲。故而確定該支撐方法采用固定-支撐的方式。
圖2-2 絲杠形變
上圖為固定-支撐安裝方式的絲杠允許最大變形量的安裝間距,從圖上可以看出,安裝間距為1000mm的該滾珠絲杠符合要求。
圖紙設(shè)方案如圖:
圖2-3 絲杠軸左端支撐方式
圖2-4 絲杠軸右端支撐方式
絲杠軸被固定于四個軸承上,左邊的一端被緊固落螺母固定,從而達到固定的目的,如圖2-3右端為支撐端。如圖2-4所示為滾珠絲杠右端支撐方式,與左端不同之處在于這端并未采用緊固螺母,為自由端。兩端都采用角接觸球軸承和深溝球軸承疊加安裝,這樣既能夠使軸既能夠承受軸向載荷,又能夠承受徑向載荷,從而滿足滾珠絲杠正常工作時的實際要求。
2.2.5螺母的選擇
螺母旋轉(zhuǎn)型滾珠絲杠,是把滾珠絲杠螺母與支撐軸承一體的螺母旋轉(zhuǎn)式滾珠絲杠裝置。其螺母為使用外循環(huán)方式的鋼球循環(huán)結(jié)構(gòu),鋼球沿著滾道從入口到出口完成不間斷的循環(huán)。而傳統(tǒng)螺母外周嵌套有一個套筒。套筒外徑與一個調(diào)心滾子軸承相連接,通過調(diào)心滾子軸承將傳統(tǒng)螺母的徑向旋轉(zhuǎn)運動,與軸向的進給運動相互分離,從而達到螺母一邊旋轉(zhuǎn),一邊軸向進給,而不影響與之相連接的工作臺只有軸向進給的需求。
圖3-1 螺母旋轉(zhuǎn)方式實現(xiàn)方案
兩臺電動機允許和絲杠軸、滾珠絲杠的螺母進行獨立聯(lián)接,并通過與螺母套筒相連接的齒輪將旋轉(zhuǎn)力矩傳遞給螺母和套筒,并可以使微量進給控制在電動機的穩(wěn)定旋轉(zhuǎn)范圍內(nèi)。因其獨立運動的特性,該設(shè)計方案可以使用兩個伺服電機驅(qū)動,令兩臺電機同時驅(qū)動的方案,將兩個速度進行組合,可以擴大整個運動副的速度控制范圍。
3.零件的初步校核
3.1容許軸向負載的計算
最大軸向負荷的計算
導(dǎo)向面的阻力 (無負荷時)
工作臺質(zhì)量
工件質(zhì)量
導(dǎo)向面上的摩擦系數(shù)
最大速度
重力加速度
加速時間
由此可知,所需數(shù)值如下。
加速度(公式3.1)
去路加速時
去路等速時
去路減速時
返程加速時
返程等速時
返程減速時
作用在滾珠絲杠上的最大軸向負荷如下所示∶
現(xiàn)在選定直徑為40mm的絲杠軸、導(dǎo)程為20mm(最小溝槽谷徑37.4mm)的絲杠軸進行撓曲載荷和容許壓縮拉伸負荷的計算:
絲杠軸撓曲載荷:
與安裝方法相關(guān)的系數(shù)
絲杠軸溝槽谷徑
(公式3.2)
容許壓縮拉伸負荷:
由此可見, 絲杠軸的挫曲載荷和容許拉伸壓縮負荷至少等于最大軸向負,因此, 滿足這些條件的滾珠絲杠在使用上沒有問題。
3.2 絲杠軸容許轉(zhuǎn)速的計算
絲杠軸直徑:40mm; 導(dǎo)程:20mm;最大速度:60000mm/min
由絲杠軸的危險速度所決定的容許轉(zhuǎn)速:
與安裝方法(安裝方法按固定-支撐)相關(guān)的系數(shù)
安裝間距(推算)
絲杠軸直徑∶40mm;導(dǎo)程∶20mm
則許用的絲杠軸的最大轉(zhuǎn)速為:
(公式3.3)
絲杠軸直徑∶40mm;導(dǎo)程∶20mm和40mm(大導(dǎo)程滾珠絲杠)
按絲杠軸的危險速度計算可得選用絲杠軸直徑為40mm和導(dǎo)程為20mm的絲杠軸沒有問題。
3.3螺母運行距離的計算
最大速度
加速時間
減速時間
加速時的運行距離:
(公式3.4)
等加速時的運行距離:
(公式3.5)
減速時的運行距離:
(公式3.6)
3.4螺母軸向平均負荷及其壽命校核
正符號方向的軸向平均負荷
因載荷方向相異,取,計算軸向平均負荷:
(公式3.7)
負符號方向的軸向平均負荷
因載荷方向相異,取,計算軸向平均負荷:
(公式3.8)
因 ,所以軸向平均負荷為。
平均轉(zhuǎn)速
每分鐘往返次數(shù)
行程 LS =1000 mm
導(dǎo)程∶
(公式3.9)
工作額定壽命
額定壽命
每分鐘平均轉(zhuǎn)數(shù)
(公式3.10)
額定運行距離壽命
額定壽命
導(dǎo)程∶
(公式3.11)
4.定位精度的探討
4.1軸向剛性的探討
對軸向剛度影響最大的是發(fā)熱變形,所以在此僅對熱變形進行校核。
假設(shè)在滾珠絲杠在轉(zhuǎn)動過程中,系統(tǒng)溫度升高5℃。這時引起的軸向定位誤差為:
(公式4.1)
4.2運行中姿勢變化的探討
假設(shè)垂直公差在±10秒以下,絲杠L因垂直公差而引起的定位誤差為∶
Δa=L×sinθ
=150×sin(±10′′)
=±0.007 mm (公式4.2)
由此可知,定位精度如下∶
(公式4.3)
4.3旋轉(zhuǎn)扭矩的探討
由外部負荷引起的摩擦扭矩如下∶
(公式4.4)
滾珠絲杠副加速時所需的慣性力矩為,則絲杠軸全長1320mm的慣性力矩如下∶
= (公式4.5)
(公式4.6)
(公式4.7)
根據(jù)上述,加速所需要的扭矩如下∶
=4.61× N·mm (公式4.8)
因此,所需扭矩如下∶
加速時,
等速時,
減速時,
5.電動機的選擇
5.1旋轉(zhuǎn)速度
電動機選擇使用AC伺服電機。最高使用轉(zhuǎn)速∶3000 r/min,電動機額定轉(zhuǎn)速∶3000 rad/min
5.2電動機扭矩
設(shè)計中選擇的AC伺服電機能產(chǎn)生的最大扭矩為
5.3扭矩的有效值
加速時
等速時
減速時
停止時∶
(公式5.1)
電動機的額定扭矩通過以上計算必須為1305N·mm,而正常使用時電動機產(chǎn)生的扭矩必須為此數(shù)值之上。市面上CA伺服電機的種類繁多,選擇余地也比較大,所以在這里我們的選擇只需滿足上述條件的精度和扭矩即可。
6.滾珠絲杠高速化研究方案
6.1 精密滾珠絲杠副實現(xiàn)高速化要解決的主要矛盾
高速化不僅僅只是將滾珠絲杠副所連接的電動機的轉(zhuǎn)速提高了這一種實現(xiàn)方案,而應(yīng)該采用整體優(yōu)化的設(shè)計方案。
1)速度較高時,整個滾珠絲杠系統(tǒng)可能會出 現(xiàn)加大的震動
系統(tǒng)共振時與臨界轉(zhuǎn)速的關(guān)系式為:
(公式6.1)
式中:
,支承系數(shù);
L,支承間距,mm;
E,材料縱向彈性模量,;
I,小徑最小慣性矩,mm4;
g,重力加速度,mm/s2;
γ,材料密度,N/mm3;
A,小徑橫截面積,mm2。
從上式可以看出,滾珠絲杠速度的控制因素不止一種[3]。
2)滾珠受安全轉(zhuǎn)速的限制
滾珠絲杠副通常使用d0n值(此處d0為絲杠的名義直徑,n為絲杠的轉(zhuǎn)速)表示滾珠絲杠副的速度極限,也稱作DN值。滾珠絲杠系統(tǒng)中的DN值越大,表明其運行的最高速度也最大,承載能力也最強。
3)溫升和熱變形的限制
高速轉(zhuǎn)動下的滾珠絲杠螺母副會發(fā)熱變形,進而降低滾珠絲杠的運動精度。
圖6-1 不同安裝方式下滾珠絲杠副的熱變形
從上圖可以看出,滾珠絲杠在不同安裝方式下,在正常工作狀態(tài)下,都會發(fā)熱變形,而不同的安裝方式下,其滾珠絲杠副的變形類型和性質(zhì)又不近相同,其中固定-支承方式下可以允許絲杠副有微小的軸向變形,但不能過大;而固定-固定形式的支承方式因為軸向的變形不允許,其發(fā)生的彎曲變形較前者則大的多;而固定-自由型的安裝方法因其自身的類似懸臂梁的結(jié)構(gòu),所以決定了它并不能承受過大的載荷而只能使用在很小的范圍內(nèi)。
4)噪聲較大,環(huán)保性差
任何機械在運行過程中都會或多或少地發(fā)出噪聲,而滾珠絲杠也不例外,高速條件下,其本身會隨著速度的提高而發(fā)出過多的噪音。
6.2 滾珠絲杠副高速化的技術(shù)對策
上述面臨的問題是滾珠絲杠副高速化的優(yōu)化目的最大的障礙。本設(shè)計依據(jù)以上的分析有針對性地提出了以下的技術(shù)和對策:
1)增大絲杠的導(dǎo)程和螺紋頭數(shù)
絲杠方面的資料和實際經(jīng)驗告訴我們提高滾珠絲杠轉(zhuǎn)速或是加大滾珠絲杠導(dǎo)程都能夠提高滾珠絲杠的運行速度。
而導(dǎo)程的增加,會導(dǎo)致絲杠的運行精度下降,而且絲杠系統(tǒng)啟動力矩也會隨之升高,影響整體傳動的平穩(wěn)性。所以我們必須在轉(zhuǎn)速和導(dǎo)程之間取得一個平衡點。從而達到滾珠絲杠副的最優(yōu)化設(shè)計。
有設(shè)計方案采用雙頭螺紋,這既能提高其剛度和承載能力,又能提高運行中的平穩(wěn)性[5]。但也不是完全一味地增大。
2)采用強冷技術(shù)
圖6-2 螺母空心冷卻液強冷方式
如圖為滾珠絲杠的發(fā)明裝置。該裝置利用加在螺母上的空心孔,通過孔中流動的冷卻液達到為滾珠絲杠副降溫的目的。
4)改進滾珠循環(huán)返向裝置和滾珠的流暢性
5)優(yōu)化滾珠反向器的結(jié)構(gòu)
發(fā)熱和噪聲都是由摩擦造成的,所以依據(jù)此原理,可以將滾道內(nèi)的摩擦系數(shù)降到最低,從而達到最根本改善和優(yōu)化滾珠絲杠副。傳統(tǒng)的滾珠絲杠使用的都有一個反向器,而其精度也決定了滾珠在滾道內(nèi)的順利運行。
6)無循環(huán)反向裝置
傳統(tǒng)循環(huán)方式中采用循環(huán)滾道的設(shè)計方案對 DN值有極大的制約,所以有人提出了無返向裝置的滾珠絲杠副。而本設(shè)計說明中緒論部分也進行過介紹,在此,將不再贅述。
圖6-3 行星滾柱絲杠副
上圖為一種新型的滾珠絲杠裝置,其使用非循環(huán)的滾柱絲杠形式,具有與滾珠絲杠不同的支撐部件,使用滾柱,加強了絲杠副的剛性和承載能力。使用壽命和正常使用速度也較普通滾珠絲杠有了很大的提升。
7)采用雙電動機驅(qū)動
兩臺獨立于絲杠軸和滾珠絲杠的螺母的電動機分別連接,并通過與螺母套筒相連接的齒輪將旋轉(zhuǎn)力矩傳遞給螺母和套筒,這樣做擴大了進給控制系統(tǒng)的穩(wěn)定旋轉(zhuǎn)速度范圍。因其獨立運動的特性,該設(shè)計方案可以使用兩個伺服電機驅(qū)動,令兩臺電機同時驅(qū)動的方案,將兩個速度進行組合,可以擴大整個運動副的速度控制范圍。
所以本課題的研究方向是探究一種能夠?qū)崿F(xiàn)滾珠絲杠的高速運行的創(chuàng)新裝置。能夠在保證精度和機械運行的穩(wěn)定性的基礎(chǔ)上,達到高速,自鎖的優(yōu)化型滾珠絲杠。
總 結(jié)
經(jīng)過這段時間的系統(tǒng)性公關(guān),對自己能力又是一次新的歷練。經(jīng)過這段時間,在老師的教導(dǎo)下,我也學(xué)會了許多新的知識和技能,畢業(yè)設(shè)計促進了自己對所學(xué)知識的掌握,并且學(xué)到了許多實踐性的東西,對自己是很有意義的。其中,有老師的諄諄教誨,龐老師對我也很嚴格,自己的也在虛心接受老師的指導(dǎo),我最應(yīng)該謝謝的人便是我的老師,他不僅僅是一個學(xué)術(shù)專業(yè)的教授,更是我在日后從事機械行業(yè)研究工作的人生導(dǎo)師。在此我也對我學(xué)到的東西進行一下簡單的總結(jié):
1) 經(jīng)過了本次畢業(yè)設(shè)計,更加鞏固了我對CAD制圖技術(shù)的熟練程度,為我日后進一步學(xué)習(xí)打下來堅實的基礎(chǔ)。
2) 老師的學(xué)術(shù)品格深深把我折服,這將是我以后人生道路中又一個指路明燈,這里我應(yīng)該好好謝謝老師。
3) 嚴謹?shù)墓接嬎闶菑氖聶C械研究的重要品行,小到微米級的計算單位大到米級的大型機械,每一個裝配尺寸都是嚴格有依據(jù)的,決不能憑空捏造,應(yīng)做到實事求是。
4) 機械工程是份神圣的行業(yè),我們每一個中國人在現(xiàn)在嚴峻的技術(shù)革命形勢下,決不能無動于衷,甘于沉浸在已經(jīng)取得的成就中,而應(yīng)該向前看,以不一樣的思維,開拓創(chuàng)新,為新機械制造業(yè)注入自己強大的動力。
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[16]THK綜合產(chǎn)品目錄.臺灣THK滾珠絲杠設(shè)計公司.互聯(lián)網(wǎng).2013-06/2016-05
[17]PMI產(chǎn)品目錄.PMI滾珠絲杠設(shè)計公司.互聯(lián)網(wǎng).2013-05/2016-05
[18]上銀產(chǎn)品目錄.上銀滾珠絲杠設(shè)計公司.互聯(lián)網(wǎng).2013-06/2016-05
致 謝
這次畢業(yè)設(shè)計中,我領(lǐng)悟了很多東西。要十分感謝我的導(dǎo)師的指導(dǎo),還有他的理解與包容。沒有老師我很難完成這篇設(shè)計。從設(shè)計資料的搜集,到最后設(shè)計的修改的整個過程中,耗費了老師很多心血和努力,我在這里表達我最真摯的感情。以后我一定以自己最大的努力,積極獻身新型機械制造業(yè),為實現(xiàn)自己的人生價值和社會價值而奮斗。以報答您對我的恩情。
九層之臺,起于累土,沒有前面其他機械老師的努力培養(yǎng),我也不可能學(xué)到如此有用的知識和能力,也非常感謝曾經(jīng)幫助過我的老師的悉心教導(dǎo)。設(shè)計過程中也有其他同學(xué)的幫助,在這里我也非常謝謝他們在大學(xué)四年最后時光的陪伴。
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International Journal of Machine Tools fax: +88656311500. E-mail addresses: jywe@sunws.nfu.edu.tw (W. Jywe), table was rotated counterclockwise. In general, one rotary table calibration for a 3601 full circle requires 36 recording if the sampled period of measurement system is 101.Ifa 0890-6955/$-see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijmachtools.2007.02.004 pmc2@sunws.nfu.edu.tw (C.J. Chen), allen@nfu.edu.tw (W.H. Hsieh), pdlin@mail.ncku.edu.tw (P.D. Lin), schong@nfu.edu.tw (H.H. Jwo), jeyang@ (T.Y. Yang). instruments are the rotary encoder, the laser interferom- eter, the autocollimator and the precision level. A rotary encoder [1] is commonly used in indexing measurement in a rotary machine, e.g. a rotary table of the multi-axis machine tool, the joint of a robot, the spindles of machine tools and the indexing of a ball screw. However, the rotary encoder is only suitable for the indexing error measure- ment. A laser interferometer [2] has often been used to measure a small angle, but it can only obtain indexing error either one dimensional (1D) error or 2D errors. The complete calibration procedure of a rotary table requires 6 DOF measurement for a 3601 full circle, but the measure- ment range of most measurement systems is smaller than 101. Therefore the measurement range of the laser interferometer and autocollimator are not enough and, in addition, they are expensive. The conventional calibration technique of the rotary table for a 3601 full circle requires one reference rotary table, which must have high accuracy and high repeatability. The error of the reference rotary C3 and the reference rotary table could be obtained. The system calibration, stability test, system verification and full circle test were completed. The angular stability of this system was less then 2arcsec, while the displacement stability was less than 1.2mm. r 2007 Elsevier Ltd. All rights reserved. Keywords: Rotary table calibration; Full circle test; Grating; Position sensing detector; 4 Degree of freedom measurement; Error separation 1. Introduction A rotary table is frequently used in industry in such things as machine tools, CMM and assembly lines. Therefore, the calibration of the rotary table is very important. The calibration of the rotary table requires an during an indexing test. An autocollimator [3] is frequently used to measure small angles and it can be applied to two dimensional (2D) angle measurement (pitch error and yaw error), but its measurement range is small and it require one standard polygon mirror. A rotary table has 6 DOF errors (3 linear position errors and 3 angular position reference rotary table, but with good repeatability is needed. After two full circle tests, the 4-DOF errors of both the target rotary table A novel simple and low cost 4 degree calibrating technique for W. Jywe a,C3 , C.J. Chen b , W.H. Hsieh a National Formosa University, Department of Automation b National Cheng-Kung University, Department of Mechanical Received 30 October 2006; received in revised form Available online Abstract For calibrating an angular rotary table, either a high precision standard employed at high cost. This paper establishes a novel, simple and low of a rotary table (three angular position errors and one linear position one 1 dimensional (1D) grating and two 2 dimensional (2D) position-sensing-detectors ture 47 (2007) 1978–1987 of freedom angular indexing a precision rotary table P.D. Lin b , H.H. Jwo a , T.Y. Yang a g, No. 64 Wenhua Rd., Huwei, Taiwan, ROC Engineering, No. 1, University Rd., Tainan, Taiwan, ROC 1 February 2007; accepted 13 February 2007 February 2007 table or a laser interferometer and related optics are normally cost technique to calibrate the 4-degrees-of-freedom (DOF) errors error) for a 3601full circle by employing one reference rotary table, (PSD). With this technique, no highly accurate ARTICLE IN PRESS more complete test is implemented, the calibration process will takes a long time. In general, the rotary table includes the index error, wobble error and eccentricity. But conventional rotary table calibration techniques (laser interferometer or auto- collimator) only calibrate the index error and the wobble error. However, the high precision rotary table must be calibrated in more details. Through the complete rotary table calibration, the errors of rotary table can be compensated. In this paper, the errors of rotary table were defined by 6 DOF, i.e. three linear position errors (d x , d y , d z ) and three angular position errors (e x , e y , e z ). The index error was represented by e z , the wobble error was represented by e x and e y , the eccentricity was represented by d x and d y . In recent years, angular measuring techniques have focused on the interferometric methods. In 1992, Huang et al. [4] developed a small angle measurement system which was based on the internal reflection effect in a glass boundary and Fresnel’s law. In Huang’s system, the resolution was 0.2arcsec and the measuring range was 3arcsec. In 1996, Xiaoli et al. [5] established a 2D small rotation angle-measurement system using two different parallel interference patterns (PIP) that were orthogonal to each other. The standard deviation of Xiaoli’s system was 0.6arcsec. In the following year Xiaoli et al. [6] improved their system so that its resolution was 0.2arcsec and measuring range was 730arcmin. In 1997, Chiu et al. [7] established a modified angle measurement technique with a resolution of 0.333arcsec and a measuring range of75.61. At its optimum performance, the system’s resolution was 0.288arcsec. In 1998, Zhou and Cai [8] established an angle measurement technique which was based on the total-internal reflection effect and heterodyne interferome- try. The system resolution was better than 0.3arcsec, depending on the refractive index selected. In 1998, Huang et al. [9] established a method of angle measurement, based on the internal reflection effects, that used a single right- angle prism. They demonstrated that angle measurement with a range of 7500arcmin, a nonlinearity error of 70.1%, and a resolution of 0.1arcsec could be readily achieved. In 1999, Guo et al. [10] developed an optical method for small angle measurement based on surface- plasma resonance (SPR), and a measurement resolution of 0.2arcsec was achieved experimentally. In 2003, Ge and Makeda [11] developed an angle-measurement tech- nique based on fringe analysis for phase-measuring profilometry. The measurement range was 72160arcsec and the deviation from linearity was better than 70.02 arcsec. In 2004, Chiu et al. [12] developed an instru- ment for measuring small angles using multiple total internal reflections in heterodyne interferometry, and the angular resolution was better than 0.454arcsec over the measurement range C02.121pyp2.121 for 20 total-internal reflections. W. Jywe et al. / International Journal of Machine Most angle-measurement technique research focuses on 1D angle measurement and interferometric angle measurement, and 2D measurement also focuses on interferometric techniques. However, interferometric systems are expensive and complex, and cannot be used extensively in industry. Therefore, the low cost and multiple DOF measurement system is needed for rotary table calibration. The position sensing detector (PSD) could be used to measure the rotary part error, the speed of rotary part, the rotation direction of rotary part, the angular position, and the indexing error [13,14]. Jywe et al. employed two PSDs and one reflective grating to test rotary table performance [15], but its measurement range was small (o11). In [15], no full circle test was implemented and no analytic solution was provided. However, for the general rotary table calibra- tion, the 3601 full circle test is necessary. This paper both describes the building of one 4-DOF measurement system and establishes a novel technique for rotary table full circle test. The 4-DOF system presented in this paper comprises one 1D reflection grating, one laser diode, four PSDs and one reference rotary table. The laser interferometer and the autocollimator were most used rotary table measurement system. However, in rotary table calibration process, the laser interferometer and the autocollimator need a high accuracy reference rotary table and a polygon mirror, respectively. Therefore, using the laser interferometer or autocollimator to calibrate rotary table is expensive. Because , the cost of 1D reflection grating, PSD, signal conditioning unit of PSD and laser diode and rotary table is about 1 5 of one laser interferometer system or 1 2 of one autocollimator system. Moreover, in the presented method, no high accurate reference rotary table, but with good repeatability is needed. Even the indexing error and the geometric error of the reference rotary table is large, they will be obtained by the presented method. 2. The 4-DOF measurement system In this paper, the 4-DOF measurement system includes one reference rotary table, one 1D grating, one laser diode, two PSDs, two PSD processors, one A/D card and one personal computer (PC). Fig. 1 shows the schematic diagram. The reference rotary table was placed on the target rotary table then the 1D grating was mounted on the rotary table by the fixture. The laser diode and PSDs were placed near the 1D grating. The laser beam from the laser diode was projected onto a 1D grating and then the 1D grating produced many diffraction light beams. In this paper, the +1 order and C01 order diffraction light beam are used, and two PSDs were used to detect the diffraction light beam. Generally six geometric errors are defined on a rotary table, namely three linear position errors and three angular position errors (pitch, roll, and yaw). The three linear position errors are d x , d y and d z , and the three angular position errors are e x , e y and e z , respectively. In addition, there are eccentricity between the grating and the axis of the rotary table, which are defined as D x and D y . Tools d x ? d xt t d xr , C15 y ? C15 yt t C15 yr ; d y ? d yt t d yr , C15 z ? C15 zt C0 C15 zr ; d z ? d zt t d zr , e13T where e z is the index difference between the target rotary table and the reference rotary table, and it accumulatively varies during the calibration procedure. The e x , e y , d x , d y and d z are not accumulative. Because one full circle test needs two tests, the repeatability of the target rotary table and the reference rotary table must be good, otherwise the measured results will not repeat. The basic requirement of the calibrating technique is that the target rotary table under calibration can be rotated the same step size as the reference rotary table in different orientations, say on for clockwise and the other counter-clockwise. Each sector of the table under test has been compared with every sector of the reference one in order to build the first set of data. For example, one rotary table was tested at 12 angular position points around 3601 (i.e. at 01,301,601,y,3301), which were equally spaced segmented in the target rotary table and the reference rotary table. At the start in 1000 C1C1C1 C010000C1C1C1 0 0100 C1C1C1 0 C010 00C1C1C1 0 0010 C1C1C1 00C0100C1C1C1 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1000 C1C1C1 0 C010 00C1C1C1 0 0100 C1C1C1 00C0100C1C1C1 0 0010 C1C1C1 000C010C1C1C1 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 4 0 0 0 0 C1C1C11 C01 0 0 0 0 C1C1C1 0 . . . C15 z1n ? C15 ztn C0 C15 zrn , e14T where e z1n is the first set of angular readings and n is the number of increments over 3601. The subscript ‘t’ of the symbol e zt1 means the error of the target rotary table and the subscript ‘r’ means the error of the reference rotary table. In the second test of full circle test, the target rotary table and reference rotary table was set to 01 again and the reference rotary table was incremented by one nominal step (ex. 301). After the rotation of the reference rotary table, the first set of sample was taken. Then, the target rotary table was rotated 301 clockwise and the reference rotary table was rotated 301 counter-clock- wise and the other sets of sample were taken. From the above experiment process, the results of second test were obtained. Then, the flowing relationship can be derived: C15 z21 ? C15 zt1 C0 C15 zr2 , C15 z22 ? C15 zt2 C0 C15 zr3 , . . . C15 z2n ? C15 ztn C0 C15 zr1 , e15T where e z2n is the second set of angular readings and n is the number of increments over 3601. The two sets of measured data can then be rearranged as follows: C15 zt1 C15 zt2 C15 zt3 . . . C15 zr1 C15 zr2 C15 zr3 . . . 2 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 4 3 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 5 ? C15 z11 C15 z12 C15 z13 . . . C15 z21 C15 z22 C15 z23 . . . 2 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 4 3 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 5 (16) C15 zrn C15 z2n and the original augmented matrix is shown as: 1000 C1C1C1 C010000C1C1C1 C15 z11 0100 C1C1C1 0 C010 00C1C1C1 C15 z12 0010 C1C1C1 00C0100C1C1C1 C15 z13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1000 C1C1C1 0 C010 00C1C1C1 C15 z21 0100 C1C1C1 00C0100C1C1C1 C15 z22 0010 C1C1C1 000C010C1C1C1 C15 z23 . . . 0 . . . 0 . . . 0 . . . 0 C1C1C11 . . . C01 . . . 0 . . . 0 . . . 0 . . . 0 C1C1C1 . . . C15 z2n 2 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 4 3 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 5 . (17) An augmented matrix of the reduced system can then be derived as follows: Since Eq. (18) is linear-dependent, more equations are required. An assumption is again made to presume that no closing error exists within the reference rotary table and consequently the following equation can be derived: C15 zr1 t C15 zr2 t C15 zr3 tC1C1C1tC15 zrnC01 t C15 zrn ? 360 C14 . (20) ARTICLE IN PRESS Table 1 Components of the prototype 4-DOF measurement system PSD UDT SC-10D, active area 100mm 2 PSD signal processor On-Trak OT-301 PC Intel Pentium4 2.0G 256MB RAM 40G HD A/D Card Advantech PCI-1716, 16 bit, sampling range 710V, Max. sampling frequency 250kHz Laser diode l ? 635nm, 5mW 1D Grating Rolled diffraction grating, 600grooves per mm, Autocollimator NewPort LDS Vector, measurement range: 2000mrad W. Jywe et al. / International Journal of Machine Tools & Manufacture 47 (2007) 1978–19871982 1000C1C1C1 C010000C1C1C1 0 C15 z11 0100C1C1C1 0 C010 00C1C1C1 0 C15 z12 0010C1C1C1 00C0100C1C1C1 0 C15 z13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0000C1C1C1 1 C010 00C1C1C1 0 C15 z21 C0 C15 z11 0000C1C1C1 01C0100C1C1C1 0 C15 z22 C0 C15 z12 0000C1C1C1 001C010C1C1C1 0 C15 z23 C0 C15 z13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0000C1C1C1 10000C1C1C1 C01 P nC01 i?1 eC15 z2i C0 C15 z1i T 0000C1C1C1 C010000C1C1C1 1 C15 z2n C0 C15 z1n 2 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 4 3 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 5 . (18) From the last two rows in the reduced matrix, it can be shown that C15 zr1 C0 C15 zrn ? X nC01 i?1 eC15 z2i C0 C15 z1i T?C0eC15 z2n C0 C15 z1n T, (19) or X nC01 i?1 eC15 z2i C0 C15 z1i T?0. Fig. 2. Photograph of the 4DOF measurement system with 4 PSD. Fig. 3. Calibration results (b) standard deviation. Eq. (20) is then incorporated into the augmented matrix in Eq. (18) to give the following: 1000 C1C1C1 C010 0 00C1C1C1 0 C15 z11 0100 C1C1C1 0 C010 00C1C1C1 0 C15 z12 0010 C1C1C1 00C0100C1C1C1 0 C15 z13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1000 C1C1C1 0 C010 00C1C1C1 0 C15 z21 0100 C1C1C1 00C0100C1C1C1 0 C15 z22 0010 C1C1C1 000C010C1C1C1 0 C15 z23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0000C1C1C11 C010 0 00C1C1C1 0 C15 z2n 0000C1C1C1011111C1C1C1 1 360 2 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 4 3 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 5 . (21) Finally, using the Gaussian Elimination method, the actual individual angle e zti and e zri at each target position can be calculated. The calculation of e xti , e xri , e yti , e yri , d xti , d xri , d yti , d yri , d zti and d zri is different to e zti and e zri . For instance, C15 x11 ? C15 xt1 t C15 xr1 , C15 x12 ? C15 xt2 t C15 xr2 , . . . C15 x1n ? C15 xtn t C15 xrn e22T and C15 x21 ? C15 xt1 C0 C15 xr2 , C15 x22 ? C15 xt2 C0 C15 xr3 , . . . C15 x2n ? C15 xtn C0 C15 xr1 . e23T The summation of e xri is C15 xr1 t C15 xr2 t C15 xr3 tC1C1C1tC15 xrnC01 t C15 xrn ? 0 C14 . (24) ARTICLE IN PRESS W. Jywe et al. / International Journal of Machine Tools & Manufacture 47 (2007) 1978–1987 1983 Fig. 4. Stability test results (a)–(d). 4. Experimental results and discussion In this paper, the calibration of the 4-DOF measurement system, system stability, system verification and full circle test were accomplished. The photograph of this system was shown in Fig. 2. Components not shown in Fig. 2 include a desktop PC connected to the PSD signal processor via an A/D card. The component specifications were listed in Table 1. 4.1. System calibration System calibration was the first experiment. In this experiment, the NewPort autocollimator was used to provide the reference angular position. Its measurement range was 7410arcsec, resolution was 0.02arcsec and accuracy was 0.5arcsec. Fig. 3(a) shows the calibration result and Fig. 3(b) gives the standard deviations for ARTICLE IN PRESS Tools & Manufacture 47 (2007) 1978–1987 Therefore, the matrix of e xti and e xri is 1000 C1C1C1 C010000C1C1C1 0 C15 x11 0100 C1C1C1 0 C010 00C1C1C1 0 C15 x12 0010 C1C1C1 00C0100C1C1C1 0 C15 x13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1000 C1C1C1 0 C010 00C1C1C1 0 C15 x21 0100 C1C1C1 00C0100C1C1C1 0 C15 x22 0010 C1C1C1 000C010C1C1C1 0 C15 x23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0000C1C1C11 C010000C1C1C1 0 C15 x2n 0000C1C1C1011111C1C1C1 10 2 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 4 3 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 5 . (25) Similarly, 1000 C1C1C1 C010 0 00C1C1C1 0 C15 y11 0100 C1C1C1 0 C010 00C1C1C1 0 C15 y12 0010 C1C1C1 00C0100C1C1C1 0 C15 y13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1000 C1C1C1 0 C010 00C1C1C1 0 C15 y21 0100 C1C1C1 00C0100C1C1C1 0 C15 y22 0010 C1C1C1 000C010C1C1C1 0 C15 y23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0000C1C1C11 C010 0 00C1C1C1 0 C15 y2n 0000C1C1C1011111C1C1C1 10 2 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 4 3 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 5 , (26) 1000 C1C1C1 C010000C1C1C1 0 d y11 0100 C1C1C1 0 C010 00C1C1C1 0 d y12 0010 C1C1C1 00C0100C1C1C1 0 d y13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1000 C1C1C1 0 C010 00C1C1C1 0 d y21 0100 C1C1C1 00C0100C1C1C1 0 d y22 0010 C1C1C1 000C010C1C1C1 0 d y23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0000C1C1C11 C010000C1C1C1 0 d y2n 0000C1C1C1011111C1C1C1 10 2 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 4 3 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 5 . (27) This technique can be used in the rotary table 6-DOF calibration, but in this paper, the measurement system could only measure 4-DOF errors, so this paper lists only four equations (Eqs. (21), (25)–(27)). The recorded count was based on the measurement range of the system. For example, the measurement range of Lin’s system (laser interferometer) [16] was about 101. W. Jywe et al. / International Journal of Machine1984 Therefore, one full circle test must record at least 36 points during the first and second tests, respectively. Fig. 5. Verification result (a) and (b). ARTICLE IN PRESS W. Jywe et al. / International Journal of Machine system uncertainty. Throughout the calibration process, it was clear that the linearity of e z was good and the uncertainty of e z was about 1.5arcsec. The angular Fig. 6. Full circle test Tools & Manufacture 47 (2007) 1978–1987 1985 position (e z ) measurement range of the 4-DOF measure- ment system was about 11 because almost all measurement r