y7063齒輪磨床分度機(jī)構(gòu)設(shè)計含6張CAD圖
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附錄1：外文翻譯
一種先進(jìn)的超精密磨床
蘭迪斯.隆德公司的生產(chǎn)精密機(jī)械的克蘭菲爾德部門，最近生產(chǎn)了一種超精密的端面磨床，該機(jī)床擁有幾個自動監(jiān)控功能。該公司免費給克蘭菲爾德大學(xué)的精密工程小組提供機(jī)床，以便他們進(jìn)行研究，特別是里外都完整的無損害的端面區(qū)部分。
本文論述了機(jī)械的設(shè)計、初加工試驗以及可能的研究項目。這些項目將因為這種先進(jìn)的機(jī)械系統(tǒng)的應(yīng)用而受益，系統(tǒng)結(jié)合了最先進(jìn)的自動檢測功能與控制加工過程功能。
關(guān)鍵詞：自動檢測 磨削 機(jī)械設(shè)計 精密機(jī)器
1 緒論
生產(chǎn)精密機(jī)械的克蘭菲爾德是UNOVA的一個子公司，它的專長是用先進(jìn)的原料生產(chǎn)和制造出價格合理的機(jī)器元件，包括陶瓷、玻璃、金屬互化物及硬質(zhì)合金鋼?？颂m菲爾德大學(xué)是以工業(yè)和制造業(yè)著稱的大學(xué)，它重視與工業(yè)界的密切聯(lián)系，而且現(xiàn)在正在開展超精密的、超高速加工的機(jī)械研究項目，包括超硬材料加工、脆性材料的韌性加工以及汽車產(chǎn)業(yè)的精密加工。這兩個團(tuán)體互補(bǔ)的研究興趣導(dǎo)致了生產(chǎn)精密機(jī)械的克蘭菲爾德公司設(shè)計和生產(chǎn)了一種先進(jìn)的超精密端面磨床給屬于SIMS的精密工程研究小組。這使得該小組擁有一系列的研究項目，特別是對于里外都完整的無損害的端面區(qū)部分。
原料的納米分散加工及控制被看作是一種中期至長期解決成本和時間問題的方法，這兩個問題折磨著電光學(xué)與其它精密零件的制造。例如：易碎原料的延展拋光能夠提供光滑的表面，事實上，它比一般的材料擁有較高的平滑度和外形精確度[1]。更重要的是,一個球表面很少或沒有經(jīng)歷表面下的損傷,因此消除了聯(lián)合傳統(tǒng)拋光進(jìn)行后續(xù)拋光的步驟。許多的“微小精密”產(chǎn)品(如半導(dǎo)體、光纖通信系統(tǒng)、計算機(jī)輔助系統(tǒng)等),以及較大的被航空、汽車等應(yīng)用的元件的性能越來越依賴于更高的幾何精度和微-納米表面。最近,汽車工業(yè)已經(jīng)顯示了未來對元件表面的要求，它需要具有幾個關(guān)鍵的傳輸元件，這種傳輸性能屬于光學(xué)性質(zhì),它的目標(biāo)是用10納米的Ra表面經(jīng)濟(jì)地完成對硬鋼的直接機(jī)械加工，而且無需對硬鋼進(jìn)行拋光。玻璃和陶瓷有無損害的表面，硬鋼有光學(xué)性質(zhì)表面，這種條件是非常嚴(yán)格的，它需要(a)一系列的機(jī)械工具，它們不是一般的最好的生產(chǎn)工具，例如，精度高、運動順暢、環(huán)硬度高[2]；(b)輔助設(shè)備的加入，人、特別是為了適應(yīng)特殊的應(yīng)用，例如砂輪的打磨維修和調(diào)節(jié)；以及(c) 使用正確的磨削技術(shù)（許多的變量—車輪的型號；冷凍劑；速度；供給等）。所有的條件都必須被滿足，現(xiàn)在能夠滿足這些條件的晶圓磨機(jī)器已經(jīng)生產(chǎn)出來。
2 目標(biāo)
為了滿足上面所提及的表面完整性和生產(chǎn)率的要求,這些要求適用于一系列的元件,主要的發(fā)展目標(biāo)包括:
1）．一個有高標(biāo)準(zhǔn)（上表面和下表面）完整性的較大的元件產(chǎn)品的機(jī)械加工效率
2）對易碎材料(眼鏡、陶瓷)優(yōu)先選擇柔軟的方式進(jìn)行機(jī)械加工
3）一個只有一個設(shè)置的單一過程來取代典型的三級研磨、腐蝕和拋光過程，能夠?qū)崿F(xiàn)更高的生產(chǎn)率。
3過程
這個過程的一個主要要求是它應(yīng)該能夠在350毫米直徑元件上進(jìn)行極度平滑表面加工的能力。而且,表面應(yīng)該是光滑的(小于50Ra)以及有最小的表面損傷。理論上，其表面的性質(zhì)應(yīng)接近于拋光表面的性質(zhì)。為了滿足這些嚴(yán)格的要求，旋轉(zhuǎn)磨削已被應(yīng)用。旋轉(zhuǎn)磨削的特性是它不像傳統(tǒng)的表面拋光，它有一個恒接觸長度和恒切削力。如圖1所示的磨削原理。砂輪、工件的旋轉(zhuǎn)以及砂輪的軸供給去除工件的表面余量，直到達(dá)到它的最后幾何厚度。
4 本機(jī)
該進(jìn)程和組件的較高要求需要質(zhì)量非常高的環(huán)剛度機(jī)。
研磨機(jī)（圖2）面的設(shè)計目標(biāo)是：
圖1關(guān)于研磨作業(yè)問題
1. 要求為達(dá)到亞微米亞表面損傷，環(huán)剛度應(yīng)該優(yōu)于200 N /m_1具有良好的動態(tài)阻尼。
2. 要實現(xiàn)總厚度 變化（TTV）的0.5 m公差，控制間距（輪部件的表面）應(yīng)該大于0.333弧秒。
3. 要實現(xiàn)亞微米亞表面損傷，切深度控制應(yīng)該優(yōu)于0.1 m。
4. 需要軸向誤差議案實現(xiàn)亞微米亞表面損傷,錠數(shù)應(yīng)該優(yōu)于0.1 m。
5. 測量與反饋元件厚度為0.5 m，以達(dá)到微米的厚度公差。
在地面幾何平面取決于相對位置的砂輪和旋轉(zhuǎn)軸工件。圖3顯示的相對運動和機(jī)軸。共有11個軸，再加上三個數(shù)字遙控加載項（未顯示），隨動控制下的所有驅(qū)動。
它們是：
S1磨削主軸
C Workhead主軸
Z進(jìn)料
X砂輪
S2修整主軸
W軸修整
A傾斜間距
B傾斜偏航
S3驅(qū)動洗刷
P探頭厚度 洗刷臂
如下所述，平面精確度可以由旋轉(zhuǎn)軸加上旋轉(zhuǎn)的疊加有適當(dāng)?shù)闹鬏S路線方法實現(xiàn)。此外，這原型研究納入機(jī)受益于以下國家的最先進(jìn)的自動功能 監(jiān)督和加工過程的控制。
4.1 調(diào)整工件和磨削 轉(zhuǎn)動平衡性
因為地面幾何表面可描述幾何方程，這兩個旋轉(zhuǎn)軸S1和C中一相對對齊（圖3）已進(jìn)行簡化。研磨進(jìn)程需要平面砂輪和工件的平面要保持作為Z軸進(jìn)給的應(yīng)用之間的特定角度。這是典型的多角度小于1度，使得工件和車輪接近于平行。這個角度是由三個測量LVDT的監(jiān)測傳感器，測量位移之間的磨主軸防護(hù)外罩，并就精密加工表面外罩。該測量傳感器放置在磨削主軸外罩周圍，大約從中心等距離輪子的主軸在車輪平面軸，處于已知的分離位置。從這些傳感器的信息是返回到控制系統(tǒng)修改控制的A - （節(jié)距），B組，（偏航）和Z -（料）軸。這是一個具有獨特的保持工件平整度功能的機(jī)器，它減少和亞表面損傷工件表面光潔度并且提高了磨削力。這扭曲影響磨削主軸workhead路線，而當(dāng)時生產(chǎn)非平坦表面。按照常規(guī)機(jī)械通過機(jī)械調(diào)整對齊和依靠力量和撓度一般可以均衡。然而，如果在這臺機(jī)器的工藝條件變化時，將會自動校準(zhǔn)補(bǔ)償。這可以通過優(yōu)化以適應(yīng)材料和車輪條件在控制系統(tǒng)軟件的變化。
如圖4..所示為Z軸伺服控制功能框圖 超精密磨床641工作面
圖2. 面對磨床
圖3. 軸的名稱
圖4 Z軸功能框圖
4.2 砂輪
粗加工和精加工的車輪是通過對一個軸的專利系統(tǒng)同心安裝,其中包括一前進(jìn)/收回機(jī)制的粗加工輪，如圖5.所示 。
為了最大限度地組成生產(chǎn)量， 將運用第一輪來獲得高的材料去除率。進(jìn)行細(xì)粒度砂輪整理，然后用獲得成品尺寸和表面完整性。
圖5單軸雙滾輪系統(tǒng)
4.3 檢測砂輪聯(lián)系
聲波放射（AE）傳感器用于建立初始 砂輪之間的接觸和組件。由于建立第一個接觸到非常精細(xì)的限制的重要性，當(dāng)完成磨削，環(huán)傳感器是用于workhead 和磨削主軸。這些都非常敏感，在主軸的正對面，靠近信號源。對機(jī)砂輪修整裝置主軸也是以使聲波放射傳感器“觸摸衣”磨輪。
4.4 磨削力自動測量
通過磨削力測量傳感器內(nèi)放置力循環(huán)以遠(yuǎn)離外部力量，例如絲杠螺母，及其相關(guān)的摩擦。測量研磨力度給出了砂輪磨損很好的體現(xiàn)。
4.5 測量砂輪磨損以及構(gòu)件厚度
砂輪磨損監(jiān)測組件一起的厚度。一個特別設(shè)計的鐵砧和LVDT探頭集會用來衡量組成部分的厚度。這是所做的最初基準(zhǔn)到鐵砧和探針的多孔陶瓷真空吸盤面臨哪些組件是固定的。
在測量元件厚度時，砧是在同一滑道為探針，接觸卡盤基準(zhǔn)與LVDT的探頭使得與面對面接觸組成部分，從而使一厚度測量。磨削車輪磨損，可讀出的位置
Z軸以及與這夾頭面對基準(zhǔn)的地位并且熱增長是衡量渦流探頭對安裝在工作砂輪和磨削主軸。任何增長都會由自動補(bǔ)償調(diào)整相對兩錠的位置。
參考資料
1. J. Corbett and D. J. Stephenson, “The control of surface integrity by precision machining and machine design”, Sbornik Predna′s?ek, Proceedings 1st International Conference of Precision Machining, Usti nad Labem, Czech Republic, pp. 31–43, 5–7 September 2001.
2. P. A. McKeown et al, “Ultra-precision, high stiffness CNC grinding machines for ductile mode grinding of brittle materials”, SPIE 1320, Infrared Technology and Applications, pp. 30–313, 1990.
3. Private communications, Xaar Technology Ltd, Cambridge, UK, 2000.
4. P. M. Rhead et al., “A long range, low noise, non contact capacitance position sensor” Proceedings, 1st Euspen Topical Conference on Fabrication and Metrology and Nanotechnology, Copenhagen, Technical University of Denmark, IPT.028.00, pp. 458–463, 28–30 May, 2000.
5. R. W. Whatmore, “Ferroelectrics, microsystems and nanotechnology”, Ferroelectrics 225, pp. 179–192 (Proceedings ECAPD, Montreux, Switzerland, August 1998).
6. P. A. Beltrao, A. E. Gee, J. Corbett, R. W. Whatmore, C. A. Goat and S. A. Impey, “Ductile mode machining of ferroelectric materials”, Proceedings, American Society for Precision Engineering
18, pp. 598-601. (Presented at the 13th Annual Meeting of the American Society for Precision Engineering St. Louis, Missouri, October 1998.)
7. C. A. Goat and R. W. Whatmore, “The effect of grinding conditions on lead zirconate titanate machinability”, Journal of the European Ceramics Society 19, pp. 1311–1313 (Proceedings Electroceramics 5, Montreux, Switzerland, August 1998).
8. P. A. Beltrao, A. E. Gee, J. Corbett and R. W. Whatmore, “The use of the ELID method to assist in the ductile machining of ferroelectric ceramics”, Proceedings, 1st International Conference and general Meeting of the European Society for Precision Engineering and Nanotechnology, pp. 470–473, 1999.
9. P. A. Beltrao, A. E. Gee, J. Corbett, R. W. Whatmore, C. A.Goat and S. A. Impey, “Ductile mode machining of commercial PZT ceramics”, Annals of the CIRP 48 (1), pp. 43–440, 1998.
10. G. F. Archer and D. J. Stephenson, “Surfacing of twin-screw extruder barrels”, Surface Engineering, 10(4), p. 221, 1994.
11. Metals Handbook, Volume 16, Machining, ASM, 1989.
12. A. P. V. Baker, private communication.
13. M. C. Shaw, Principles of Abrasive Processing, Oxford University Press, New York. 1996.
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附錄2：外文原文
An Advanced Ultraprecision Face Grinding Machine
J. Corbett1, P. Morantz1, D. J. Stephenson1 and R. F. Read2
1School of Industrial & Manufacturing Science, Cranfield University, Bedford, UK; 2Cranfield Precision, Division of Landis Lund, Cranfield University, Cranfield, Bedford, UK
Cranfield Precision, Division of Landis Lund, has recently developed an ultraprecision face grinding machine which incor-porates several automatic supervision features. The company supplied the machine to Cranfield University’s Precision Engin-eering Group in order that the group can undertake research, particularly in the area of damage-free grinding with high surface and subsurface integrity. The paper discusses the design of the machine, initial machining trials and potential research projects. Such projects will benefit from the avail-ability of such an advanced machine system which incorporates many state-of-the-art features for the automatic supervision and control of the machining process.
Keywords: Automatic supervision; Grinding; Machine tool design; Precision machining
1. Introduction
Cranfield Precision, which is a UNOVA Company, specialises in the design and manufacture of machines for cost-effective production of components in advanced materials including ceramics, glasses, intermetallics and hard alloy steels. The School of Industrial and Manufacturing Science (SIMS), Cran-field University, places great importance on developing close collaborative links with industry and is currently undertaking a range of ultraprecision and high-speed machining research projects including superabrasive machining, ductile machining of brittle materials and precision machining for the automotive industry. The complementary research interests of the two organisations have resulted in Cranfield Precision developing and supplying an advanced ultraprecision face grinding machine to the Precision Engineering Research Group within SIMS. This will enable the group to undertake a wide range of research programmes, particularly in the area of damage-free grinding with high surface and sub surface integrity.
Correspondence and offprint requests to: Prof. J. Corbett, School of Industrial and Manufacturing Science, Cranfield University, Bedford MK43 0AL, UK. E-mail: j.corbett cranfield.ac.uk.
Materials processing with nanometric resolution and control is viewed as a mid- to long-term solution to the cost and time problems that plague the manufacturing of electro-optics and other precision components. For example, ductile grinding of brittle materials can provide surfaces, as ground, to nanometre smoothness and figure accuracy at higher production rates than usually encountered [1]. More significantly, a ductile ground surface experiences little or no subsurface damage, thereby eliminating the need for the subsequent polishing step associa-ted with conventional grinding. The performance of many “microfeatured” products (e.g. semiconductor, optical communi-cations systems, computer peripherals, etc.), as well as larger components for aerospace and automotive applications, depends increasingly on higher geometric accuracies and micro- and nanostructured surfaces. Recently, the automotive industry has indicated a future requirement for the surfaces of certain key transmission components to be of “optical” quality, with targets of 10 nm Ra surface finish to be economically produced on hardened steel by direct machining, without polishing.
The conditions under which damage-free surfaces can be produced on glasses and ceramics, and “optical” surfaces can be produced on hardened steel, are exacting, requiring (a) the use of a class of machine tool not normally found in even the best production facilities, e.g. high accuracy, smoothness of motion, loop stiffness [2], (b) the incorporation of ancillary features specially developed to suit the particular application (e.g. grinding wheel truing and conditioning), and (c) the use of the correct grinding technology for the application (many variables – wheel type, coolant, speeds, feeds, etc). All the conditions must be satisfied and the wafer face grinding machine has been developed to meet them.
2. Objectives
In order to meet the demands of surface integrity and pro-ductivity mentioned above, for a wide range of components, the principal objectives include the development of:
1. A machining process capability for the manufacture of sizeable components with high levels of surface/subsurface integrity.
640 J. Corbett et al.
2. Optimised “ductile mode” machining processes for brittle materials (glasses and ceramics).
3. A single process, with only one set-up, to replace the typical three-stage lapping, etching and polishing process, resulting in much higher productivity.
3. The Process
A prime requirement of the process is that it should be capable of machining extremely flat surfaces on workpieces up to 350 mm diameter. Further, the surfaces should be smooth (<50 nm Ra) and have minimum subsurface damage. Ideally the surface should be close to the quality obtained by polishing. In order to meet these demanding requirements rotation grinding is utilised. A feature of rotation grinding is that unlike conven-tional surface grinding, it has a constant contact length and constant cutting force. Figure 1 illustrates the grinding prin-ciple. Both the cup grinding wheel and workpiece rotate and the axial feed of the grinding wheel removes stock from the surface of the workpiece until it reaches its final thickness/geometry.
4. The Machine
The demanding requirements of the process and component quality necessitate a machine of extremely high loop stiffness. The design targets for the face grinding machine (Fig. 2) are:
Fig. 1. Face grinding operation.
1. Loop stiffness better than 200 N mm21 with good dynamic damping, required to achieve submicron subsurface damage.
2. Control of pitch (wheel to component surface) to better than 0.333 arc seconds, required to achieve a total thickness variation (TTV) tolerance of 0.5 mm.
3. Control of cut-depth to better than 0.1 mm, required to achieve submicron subsurface damage.
4. Axial error motions of spindles better than 0.1 mm, required to achieve submicron subsurface damage.
5. Measurement and feedback of component thickness to 0.5 mm, required to achieve micron thickness tolerance.
The geometry of the ground flat surface is determined by the relative position of the rotary axes of the grinding wheel and workpiece. Figure 3 indicates the relative machine motions and axes. There are 11 axes, plus three automatic robot loading motions (not shown), all driven under servo control. These are:
S1 Grinding spindle
C Workhead spindle
Z Infeed
X Crossfeed
S2 Truing spindle
W Dressing axis
A Tilt pitch
B Tilt yaw
S3 Chuck wash brush
P Probe thickness
Wash arm
As described below, the flatness accuracy can be achieved by the superimposed rotations of the rotary axes coupled with an appropriate spindle alignment strategy. Further, this prototype research machine benefits from the incorporation of the following state-of-the-art features for the automatic supervision and control of the machining process.
4.1 Adjustment of the Workpiece and Grinding
Wheel Planarity
The relative alignment of the two rotary spindles S1 and C (Fig. 3) is simplified because the geometry of the ground surface can be described by geometrical equations. The grind-ing process requires a specific angle between the plane of the grinding wheel and the plane of the workpiece to be maintained as the Z-axis infeed is applied. This angle is typically much less than a degree, so that the workpiece and wheel are nearly parallel. This angle is monitored by three gauging LVDT sensors which measure the displacement between the grinding spindle housing, and a precision-machined surface on the work-spindle housing. The gauging sensors are placed around the grinding spindle housing, roughly equidistant from the centre of the wheel spindle axis in the plane of the wheel, at a known separation. The information from these sensors is fed back into the control system to amend the control for the A-(pitch), B- (yaw) and Z- (infeed) axes. This is a unique feature of the machine, to maintain workpiece flatness because, as the workpiece subsurface damage reduces and the surface finish improves the grinding forces increase significantly. This has the effect of distorting the grinding spindle to workhead align-ment, which then produces non-flat surfaces. On conventional machines this alignment is adjusted by mechanical trial-and-error adjustment, and relies on the force and deflection always being uniform. However, on this machine if the process con-ditions are changed, the alignment is automatically compensated for. This can then be optimised to suit the material and wheel conditions by changes in the software of the control system. A functional block diagram for the servo control of the Z-axis is illustrated in Fig. 4.
Fig. 2. Face grinding machine.
Fig. 3. Axes nomenclatu
642 J. Corbett et al.
Fig. 4
. Z-axis functiona block diagram.
ig. 5. Single axis dual wheel system.
4.6 Ancillary Features
The machine also has facilities for on machine component and chuck washing and also a robotic loading and unloading capa-bility to load and unload automatically components onto and from the workhead spindle.
References
1. J. Corbett and D. J. Stephenson, “The control of surface integrity by precision machining and machine design”, Sbornik Predna′s?ek, Proceedings 1st International Conference of Precision Machining, Usti nad Labem, Czech Republic, pp. 31–43, 5–7 September 2001.
2. P. A. McKeown et al, “Ultra-precision, high stiffness CNC grind-ing machines for ductile mode grinding of brittle materials”, SPIE 1320, Infrared Technology and Applications, pp. 30–313, 1990.
3. Private communications, Xaar Technology Ltd, Cambridge, UK, 2000.
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