機床主軸設計及相關技術研究-數控銑床的主軸結構【含8張cad圖紙+文檔全套資料】
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畢 業(yè) 設 計 任 務 書
1.畢業(yè)設計的任務和要求:
掌握機床主軸的基本知識;掌握機床主軸設計的技術關鍵;研究數控機床主軸單元的關鍵技術,掌握其相關知識及選型、應用、設計方法等;完成一種數控銑床主軸單元的設計,要求主軸工作的轉速可達8000r/min,輸出功率可達5kW,使用40柄刀具。
2.畢業(yè)設計的具體工作內容:
1) 分析題目要求,查閱相關的國內外文獻、設計資料、有關專利文獻等,在此基礎上,了解開題報告的撰寫方法、基本要求,完成開題報告;
2) 學習和掌握機床主軸的有關知識,了解主軸單元、電主軸的有關知識及發(fā)展現狀;了解數控機床、加工中心對主軸的要求;總結機床主軸的設計要點、技術關鍵及發(fā)展方向;力爭提出主軸設計的發(fā)展方向;
3) 按題目要求,設計一種數控銑床的主軸單元,完成裝配圖及主要零件圖,給出功率、強度、剛度、軸承等必要的計算;
4) 編寫設計說明書;
5) 翻譯本專業(yè)外文科技文獻一份。
畢 業(yè) 設 計 任 務 書
3.對畢業(yè)設計成果的要求:
1)主軸裝配圖、主要零件圖;
2)主軸技術的研究及設計說明書一份;
3)本專業(yè)外文科技文獻譯文一份。
4.畢業(yè)設計工作進度計劃:
起 迄 日 期
工 作 內 容
2016年
02月29日 ~03月21日
03月22日 ~04月30日
05月01日 ~05月20日
05月21日 ~05月31日
06月01日 ~06月05日
分析課題要求,查閱相關文獻資料,了解機床主軸設計的國內外現狀及發(fā)展趨勢,提出自己的設計思路,完成開題報告;
全面掌握主軸相關的基本知識,了解高速主軸的關鍵技術,了解主軸單元的設計特點;分析總結主軸技術的發(fā)展方向;
設計主軸,完成裝配圖和主要零件圖;
完成研究總結及設計說明書
撰寫答辯講稿,準備答辯;
學生所在系審查意見:
同意下發(fā)任務書
系主任:
2016年 2 月 29 日
畢 業(yè) 設 計 開 題 報 告
1.結合畢業(yè)設計課題情況,根據所查閱的文獻資料,撰寫2000字左右的文獻綜述:
文 獻 綜 述
1.1國內外機床主軸研究現狀
(1)國內研究現狀
目前國內研究高速電主軸的科研機構有我國河南省洛陽軸承研究所 ,他們能自行研究開發(fā)電主軸 ,其DmN值達到了很高的水平 ;廣州鉅聯高速電主軸有限公司研發(fā)的大功率靜壓軸承電主軸曾獲得日內瓦國際專利技術博覽會金獎 ;廣東工業(yè)大學高速加工和機床研究所也開發(fā)了數控銑床高速電主軸。其主要技術指標為 :電主軸的額定功率是 13.5kW ,最高轉速為 180 0 0r/min ,在額定轉速 5 0 0r/min時產生最大輸出轉矩為 85Nm。在我國的安陽市 ,有一家中外合資的電主軸生產廠家———安陽萊必泰機械有限公司 ,它擁有先進的電主軸、機床主軸設計和制造技術。該公司研制生產的加工中心電主軸 ,采用先進技術 ,配有矢量閉環(huán)控制系統 ,能對主軸實行恒功率調速 ,準停制動。功率為 3.7~ 2 5kW ,恒功率段 15 0 0~ 12 0 0 0r/min。采用進口高速精密軸承 ,旋轉件經高精度平衡。該系列產品具有高精度、高剛度、高速度、低噪聲、低振動、低溫升等優(yōu)點 ,系99國家火炬計劃項目。
(2)國外研究現狀
國外高速電主軸技術由于研究較早 ,技術水平也處于領先地位 ,電主軸已越來越多地應用到工業(yè)制造業(yè)中。著名的有瑞士的Fisher公司、Ibag公司、德 國的GMN公司、Hofer公司、Siemens公司、意大利Faemat公司、Gamfior公司及美國Ingersoll公司、日本Okuma公司和Fanuc公司等,它們的技術水平代表了這個領域的世界先進水平。
這些公司生產的電主軸較之國內生產的有以下幾個特點 :①功率大、轉速高。②采用高速、高剛度軸承。國外高速精密主軸上采用高速、高剛度軸承 ,主要有陶瓷軸承和液體動靜壓軸承 ,特殊場合采用空氣潤滑軸承和磁懸浮軸承。③精密加工與精密裝配工藝水平高。④配套控制系統水平高。這些控制系統包括轉子自動平衡系統、軸承油氣潤滑與精密控制系統、定轉子冷卻溫度精密控制系統、主軸變形溫度補償精密控制系統等。并在此基礎之上,這些外國廠家如美國、日本、德國、意大利和瑞士等工業(yè)發(fā)達國家已生產了多種商品化高速機床。如瑞士米克朗公司 ,就是世界上著名的精密機床制造商。它生產的機床配備最高達 6 0 0 0 0r/min的高速電主軸 ,可以滿足不同的切削要求 ,所有的電主軸均裝有恒溫冷卻水套對主軸電機和軸承進行冷卻 ,并通過高壓油霧對復合陶瓷軸承進行潤滑。所有的電主軸均采用矢量控制技術 ,可以在低轉速時輸出大扭矩。
國產電主軸和國外產品相比較 ,無論是性能、品種和質量都有較大差距 ,國產電主軸產品和國外的相比較 ,主要存在以下差距 :(1)國外電主軸低速段的輸出扭矩最大可達 30 0Nm ,而我國目前僅在 10 0Nm以內。(2 )在高轉速方面 ,國外用于加工中心的電主軸轉速已達 75 0 0 0r/min ,我國則多在15 0 0 0r/min以內。(3)電主軸的軸承潤滑 ,國外普遍采用油氣潤滑 ,而我國仍用油脂潤滑。(4 )其他配套技術也有較大差距 ,如主軸電機矢量控制、交流伺服控制技術、精確定向技術、快速啟動、停止等。(5 )在產品的品種、規(guī)格、數量和制造規(guī)模等方面 ,國產電主軸仍然處于小量研發(fā)試制階段 ,沒有形成系列化、專業(yè)化 ,遠不能滿足國內數控機床和加工中心發(fā)展的需求。所以目前國產的高轉速、高精度數控機床和加工中心所用的電主軸 ,仍然主要從國外進口。
1.2主軸技術的發(fā)展趨勢
1)繼續(xù)向高速度、高剛度方向發(fā)展
由于高速切削和實際應用的需要,隨著主軸軸承及其潤滑技術、精密加工技術、精密動平衡技術、高速刀具及其接口技術等相關技術的發(fā)展,數控機床用電主軸高速化已成為目前發(fā)展的普遍趨勢,如鉆、銑用電主軸,瑞士IBAG的HF42的轉速達到140000r/min,英國WestWind公司的PCB鉆孔機電主軸D1733更是達到了250000r/min;加工中心用電主軸,瑞士FISCHER最高轉速達到42000r/min,意大利CAMFIOR達到了75000r/min。在電主軸的系統剛度方面,由于軸承及其潤滑技術的發(fā)展,電主軸的系統剛度越來越大,滿足了數控機床高速、高效和精密加工發(fā)展的需要。
2) 向高速大功率、低速大轉矩方向發(fā)展
根據實際使用的需要,多數數控機床需要同時能夠滿足低速粗加工時的重切削、高速切削時精加工的要求,因此,機床電主軸應該具備低速大轉矩、高速大功率的性能。如意大利CAMFIOR、瑞士Step—Tec、德國GMN等制造商生產的加工中心用電主軸,低速段輸出轉矩到200Nm以上的已經不是難事,德國CYTEC的數控銑床和車床用電主軸的最大扭矩更是達到了630N·m;在高速段大功率方面,一般在l0~50kW;CYTEC電主軸的最大輸出功率為50kW;瑞士Step—Tec電主軸的最大功率更是達到65kW(S1),用于航空器制造和模具加工;更有電主軸功率達到80kW 的報道。
3) 進一步向高精度、高可靠性和延長工作壽命方向發(fā)展
用戶對數控機床的精度和使用可靠性提出了越來越高的要求,作為數控機床核心功能部件之一的電主軸,要求其本身的精度和可靠性隨之越來越高。如主軸徑向跳動在0.001mm 以內、軸向定位精度<0.0005mm以下。同時,由于采用了特殊的精密主軸軸承、先進的潤滑方法以及特殊的預負荷施加方式,電主軸的壽命相應得到了延長,其使用可靠性越來越高。Step—Tec的電主軸還加裝了加速度傳感器,降低軸承振動加速度水平,為了監(jiān)視和限制軸承上的振動,安裝了振動監(jiān)測模塊,以延長電主軸工作壽命。
4) 快速啟動、停止響應速度加快
為縮短輔助時間,提高效率,要求數控機床電主軸的啟、停時間越短越好,因此需要很高的啟動和停機加(減)速度。目前,國外機床電主軸的啟、停加速度可達到lg以上,全速啟、停時間在ls以內。
5) 軸承及其預加載荷方式、潤滑方式多樣化
除了常規(guī)的鋼制滾動軸承外,近年來陶瓷球混合軸承越來越得到廣泛的應用,潤滑方式有油脂、油霧、油氣等,尤其是油氣潤滑方法(又Oil-air),由于具有適應高速、環(huán)保節(jié)能的特點,得到越來越廣泛的推廣和應用;滾動軸承的預負荷施加方式除了剛性預負荷(又稱定位預負荷)、彈性預負荷(又稱定壓預負荷)之外,又發(fā)展了一種智能預負荷方式,即利用液壓油缸對軸承施加預負荷,并且可以根據主軸的轉速、負載等具體工況控制預負荷的大小,使軸承的支承性能更加優(yōu)良。在非接觸形式軸承支承的電主軸方面,如磁浮軸承、氣浮軸承電主軸(瑞士IBAG等)、液浮軸承電主軸(美國Ingersoll等)等已經有系列商品供應市場。
6)向多功能、智能化方向發(fā)展
在多功能方面,有角向停機精確定位(準停)、C軸傳動、換刀中空吹氣、中空通冷卻液、軸端氣體密封、低速轉矩放大、軸向定位精密補償、換刀自動動平衡技術等。在智能化方面,主要表現在各種安全保護和故障監(jiān)測診斷措施,如換刀聯鎖保護、軸承溫度監(jiān)控、電機過載和過熱保護、松刀時軸承卸荷保護、主軸振動信號監(jiān)測和故障異常診斷、軸向位置變化自動補償、砂輪修整過程信號監(jiān)測和自動控制、刀具磨損和損壞信號監(jiān)控等,如Step-Tec 電主軸安裝有診斷模塊,維修人員可通過紅外接口讀取數據,識別過載,統計電主軸工作壽命。
參考文獻
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[2]韓秋實.械制造技術基礎.北京:機械工業(yè)出版社,2010
[3] 谷玉芳.立式加工中心主軸箱的抗振特性研究和拓撲優(yōu)化設計[D].陜西科技大學 2012.
[4]秦大同.謝里陽.現代機械設計手冊(第1卷).化學工業(yè)出版社,2011,03
[5]孫開元.駱素君.常見機構設計及應用圖例.化學工業(yè)出版社,2010,07
[6]凌云.朱金生.機械設計實用機構運動仿真圖解.電子工業(yè)出版社,2014,01
[7]楊雪寶.機械制造裝備與設計.西北工業(yè)大學出版社,2010.
[8] 李國斌.機械設計基礎.機械工業(yè)出版社出版,2010
[9]辛文彤.Solidworks2012中文版從入門到精通.人民郵電出版社, 2012,01
[10]詹迪維.Solid Works高級應用教程(2012中文版).機械工業(yè)出版社,2012,03
[11] 呂建法,閆兵,王文芝.鏜銑床有限元建模及其瞬態(tài)動力學分析[J].機械工程師. 2012(12).
[12] 任小星.BFK150/2鏜銑床主軸夾緊裝置的改造[J].制造技術與機床.2016(02).
[13] 劉超峰,張功學,張淳,陳英.DVG850高速立式加工中心主軸箱靈敏度分析[J].組合機床與自動化加工技術.2010(10).
[14] 張霄.機床主軸箱的固定聯接及其結構方案設計[D].大連理工大學2015.
[15] 張樂平.面向重載數控車床的主軸箱結構優(yōu)化[D].南京航空航天大學2014.
[16] 陸暢.重型數控車床主軸箱的分析及優(yōu)化[D].沈陽航空航天大學2014.
[17] 梁東旭.球面車磨床主軸箱及其關鍵零件的有限元分析與優(yōu)化[D].蘭州理工大學 2013.
[18] 韓君.組合機床主軸箱智能設計系統的研究[D]. 河北農業(yè)大學 2012
畢 業(yè) 設 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):
2.1研究或解決的問題
(1)通過對自己所查找的相關資料,了解掌握銑床主軸的基本知識。
(2)熟悉銑床主軸單元的關鍵技術,掌握其相關知識及選型、應用、設計方法等。
(3)學會CAD設計軟件,完成相應的工程圖設計。
(4)編寫說明書。
2.2擬采用的設計方案
(1)本次設計擬采用數控銑床的電主軸,其結構如圖所示:
圖1 數控銑床主軸結構圖
(2)主軸伺服驅動器的選擇:由于本次設計要求主軸工作轉速達8000r/min,輸出功率達5KW,可采用深圳步科的伺服驅動器。具體的相關的技術參數如下:控制器等級,0.75Kw~75Kw;調速范圍,0r/min~15000r/min(四級電機);0r/min~30000r/min(二級電機);本次的電機的主功率為5Kw,轉速8000r/min。
(3)確定主軸的主要結構參數:確定主軸的軸徑、主軸前端懸伸量和主軸主要支承間的跨距。
(4)利用CAD軟件繪制工程圖。
2.3擬采用的研究思路和手段
初步擬采用理論分析和結構設計相結合的研究方法。針對銑床主軸單元設計主要采取以下方法:
①收集國內外相關研究資料,對其進行詳細分析并總結各自方案的優(yōu)缺點;通過對比國內外研究情況,提出自己的看法,擁有自己的創(chuàng)新點。
②通過對機構進行總體分析并詳細設計,初步確定本設計的研究思路。
③總結自己的思路,并與指導老師、同學們進行交流,最終確保本畢業(yè)設計思路的正確性和可行性。
④在做畢業(yè)設計的過程中,如果遇到疑問或問題,及時與老師溝通交流;最終完成銑床主軸變速箱設計。
⑤撰寫畢業(yè)設計說明書,準備答辯。
進度安排:
2月29日-3月3日:查閱資料
3月4日-3月21日 :撰寫開題報告
3月22日-5月18日:確定優(yōu)化方案
5月19日-6月1日: 完成畢業(yè)論文初稿
6月2日—6月5日:根據指導老師意見,修改論文初稿,完成終稿,準備答辯
畢 業(yè) 設 計 開 題 報 告
指導教師意見:
報告表明,該同學近期查閱了大量文獻資料,特別是企業(yè)產品的技術資料,對數控機床、電主軸等有了一些新認識。對國內外采用了什么新技術,關鍵技術等還有些不足。
但對設計任務基本明確。
同意開題。
指導教師:
2016 年 3 月 22 日
所在學院審查意見:
同意開題
負責人:
2016 年 3 月 22 日
Machine tool spindle units1 IntroductionMachine tool spindles basically fulfill two tasks:rotate the tools (drilling, milling and grinding) or work piece (turning) precisely inspace transmit the required energy to the cutting zone for metal removalObviously spindles have a strong influence on metal removal rates and quality of the machinedparts. This paper reviews the current state.and presents research challenges of spindle technology.1.1.Historical reviewClassically, main spindles were driven by belts or gears and the rotational speeds could only bevaried by changing either the transmission ratio or the number of driven poles by electricalswitches.Later simple electrical or hydraulic controllers were developed and the rotational speed of thespindle could be changed by means of infinitely adjustable rotating transformers (Ward Leonardsystem of motor control).The need for increased productivity led to higher speed machiningrequirements which led to the development of new bearings, power electronics and invertersystems. The progress in the field of the power electronics (static frequency converter) led to thedevelopment of compact drives with low-cost maintenance using high frequency three-phaseasynchronous motors.Through the early 1980s high spindle speeds were achievable only by usingactive magnetic bearings. Continuous developments in bearings, lubrication, the rolling elementmaterials and drive systems (motors and converters) have allowed the construction of direct drivemotor spindles which currently fulfill a wide range of requirements.1.2. Principal setupToday, the overwhelming majority of machine tools are equipped with motorized spindles.Unlike externally driven spindles, the motorized spindles do not require mechanical transmissionelements like gears and couplings.The spindles have at least two sets of mainly ball bearing systems. The bearing system is thecomponent with the greatest influence on the lifetime of a spindle. Most commonly the motor isarranged between the two bearing systems.Due to high ratio of power to volume active cooling is often required, which is generallyimplemented through water based cooling. The coolant flows through a cooling sleeve around thestator of the motor and often the outer bearing rings.Seals at the tool end of the spindle prevent the intrusion of chips and cutting fluid. Often this isdone with purge air and a labyrinth seal.A standardized tool interface such as HSK and SK is placed at the spindles front end. Aclamping system is used for fast automatictool changes. Ideally, an unclamping unit (drawbar)which can also monitor the clamping force is needed for reliable machining. If cutting fluid has tobe transmitted through the tool to the cutter, adequate channels and a rotary union become requiredfeatures of the clamping system.Today, nearly every spindle is equipped with sensors for monitoring the motor temperature(thermistors or thermocouples) and the position of the clamping system. Additional sensors formonitoring the bearings, the drive and the process stability can be attached, but are not common inmany industrial applications.1.3. State of the artSpindles with high power and high speeds are mainly developed for the machining of largealuminum frames in the aerospace industry. Spindles with extremely high speeds and low powerare used in electronics industry for drilling printed circuit boards (PCB).1.4. Actual development areas in industryCurrent developments in motor spindle industrial application focus on motor technology,improving total cost of ownership(TCO) and condition monitoring for predictive maintenanceAnother central issue is the development of drive systems which neutralize the existing constraintsof power and output frequency while reducing the heating of the spindle shaft.Particular attention was paid to the increase of the reliable reachable rotational speeds in the past.However, the focus has changed towards higher torque at speeds up to 15,000 rpm. Because ofIncreased requirements in reliability, life-cycle and predictable maintenance the conditionmonitoring systems in motor spindles have become more important. Periodic and/or continuousobservation of the spindle status parameters is allowing detection of wear, overheating andimminent failures.Understanding the life cycle cost (LCC) of the spindles has steadily gained importance inpredicting their service period with maintenance, failure and operational costs.2. Fields of application and specific demandsSpindles are developed and manufactured for a wide range of machine tool applications with acommon goal of maximizing the metal removal rates and part machining accuracy.The work materials range from easy to machine materials like aluminum at high speeds withhigh power spindles, to nickel and titanium alloys which require spindles having high torque andstiffness at low speeds. Cutting work materials with abrasive carbon or fiber-reinforced plastics(FRP) content need good seals at the spindle front end.Spindles for drilling printed circuit boards operate in the angular speed range of 100,000 to300,000 rpm. The increase in productivity and speed in this application field over the last fewyears was possible with the development of precision air bearings.Spindles used in die and mould machining have to fulfill the roughing operations (highperformance cutting, HPC) at high feed rates as well as the finishing processes (high-speed cutting,HSC) at high cutting speeds. Depending on the strategy and the machinery of the mould and dieshop either two different machine tools equipped with two different spindles are used or onemachine is equipped with a spindle changing unit. Another possibility is to use a spindle which canfulfill both, HSC and HPC conditions, but this still remains a compromise regarding overallproductivity.Aerospace spindles are defined by high power as well as high rotational speeds. Todaysspindles allow a material removal rate(MRR) of more than 10 l of aluminum per minute.Grinding is a finishing operation where high accuracy is necessary, which requires stiff spindleswith bearings having minimum runout. The present internal cylindrical grinding spindles have arunout requirement of less than 1 mm.Spindle units which are used mainly for boring and drilling operations require high axialstiffness, which is achieved by using angular contact bearings with high contact angles. On thecontrary, high-speed milling operations use spindles with bearings having small contact angles inorder to reduce the dependency of radial stiffness on the centrifugal forces.Contemporary machining centers tend to have multi functions where milling, drilling, grindingand sometimes honing operations can be realized on the same work piece. The bottleneck for theenhancement of the multi-technology machines is still the spindle, which cannot satisfy all themachining operations with the same degree of performance. Reconfigurable and modular machinetools require interchangeable spindles with standardized mechanical, hydraulic, pneumatic andelectrical interfaces.3. Spindle analysisThe aim of modeling and analysis of spindle units is to simulate the performance of the spindleand optimize its dimensions during the design stage in order to achieve maximum dynamicstiffness and increased material removal rate with minimal dimensions and power consumption.The mechanical part of the spindle assembly consists of hollow spindle shaft mounted to a housingwith bearings. Angular contact ball bearings are most commonly used in high-speed spindles dueto their low-friction properties and ability to withstand external loads in both axial and radialdirections. The spindle shaft is modeled by beam, brick or pipe elements in finite elementenvironment. The bearing stiffness is modeled as a function of ball bearing contact angle, preloadcaused by the external load or thermal expansion of the spindle during operation. The equation ofmotion is derived in matrix form by including gyroscopic and centrifugal effects, and solved toobtain natural frequencies, vibration mode shapes and frequency response function at the toolattached to the spindle. If the bearing stiffness is dependent on the speed, or if the spindle needs tobe simulated under cutting loads, the numerical methods are used to predict the vibrations alongthe spindle axis as well as contact loads on the bearings.Spindle simulation models allow for the optimization of spindle design parameters either toachieve maximum dynamic stiffness at all speeds for general operation, or to reach maximum axialdepth of cut at the specified speed with a designated cutter for a specificmachining application.The objective of cutting maximum material at the desired speed without damaging the bearingsand spindle is the main goal of spindle design while maintaining all other quality and performancemetrics, e.g. accuracy and reliability.does not always lead to accurate identification of the spindles dynamicparameters; A.3.2. Theoretical modelingTheoretical models are based on physical laws, and used to predict and improve theperformance of spindles during the design stage. The models provide mathematical relationbetween the inputs F (force, speed) and the outputs q (deflections, bearing loads, and temperature).The mathematical models can be expressed in state space forms or by a set of ordinary differentialequations. In both cases linear or nonlinear behavior of the spindles can be modeled.3.2.1. Mechanical modeling of shaft and housingFinite element (FE) methods are most commonly used to model structural mechanics anddynamics of the spindles. The method is based on discretization of the structure at finite elementlocations by partial derivative differential equations. The analysis belongs to the class of rotor-dynamic studies where the axis-symmetric shaft is usually modeled by beam elements, which leadto construction of mass (Me) and stiffness (Ke) matrices.Timoshenko beam element is most commonly used because it considers the bending, rotaryinertia and shear effects, hence leads to improved prediction of natural frequencies and modeshapes of the spindle .The element PIPE16 of the commonly known FEA software ANSYS is alsoan implementation of the Timoshenko theory and use the mass matrix and stiffness matrixAs an example in the finite element model in Fig. 1, the black dots represent nodes, and eachnode has three Cartesian translational displacements and two rotations . The pulley is modeled as arigid disk, the bearing spacer as a bar element, and the nut and sleeve as a lumped mass. Thespindle in this case has two front bearings in tandem and three bearings in tandem at the rear. Thefive bearings are in overall back-to-back configuration. The tool is assumed to be rigidlyconnected to the tool holder which is fixed to the spindle shaft rigidly or through springs withstiffness in both directions translation and rotation. The flexibility of the spindle mounting has tobe reflected in the model of the spindle-machine system. Springs are also used between the spindlehousing and spindle head, whose stiffness is obtained from experience.Fig. 1. The finite element model of the spindle-bearing-machine-tool system
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