本文關鍵詞： 高精機床 熱力耦合 數值模擬 接觸剛度 進給單元 動態(tài)精度　出處：《哈爾濱工業(yè)大學》2016年博士論文　論文類型：學位論文

【摘要】：高速、高精數控機床是影響和制約電子制造業(yè)水平和電子信息產業(yè)基礎配套能力的重要因素。近年來,隨著信息、通訊、醫(yī)療、航空航天等領域的電子產品向高功能、高密度及高可靠性發(fā)展,對數控機床加工精度、效率及穩(wěn)定性提出了更高要求。熱誤差是影響高精機床動態(tài)加工精度的決定性因素,占全部加工誤差的70%。因此,開展工程熱誤差機理的研究對于解決高精機床普遍存在熱穩(wěn)定性差的技術瓶頸具有重要意義。整機熱動態(tài)性能是溫度場在結構上產生的復雜熱應力、非線性變形及構件間熱力耦合效應的綜合體現(xiàn),因此不能孤立研究局部系統(tǒng)的熱現(xiàn)象。本文從全局角度分析了機床系統(tǒng)內部結構單元及整機在熱力耦合效應下的靜、動態(tài)精度特性及演變規(guī)律,主要內容如下:直線滾動導軌非線性剛度分析�；贖ertz接觸理論,考慮接觸體彈性變形及預緊效應建立了導軌初始剛度模型,量化了上、下滾道初始剛度隨外載呈相反趨勢的非線性變化特性。通過對導軌滾珠差動滑動、彈性滯后及自旋運動的摩擦能解析,計算了滾動界面的等效熱源強度,并基于Achard磨損理論建立了導軌接觸界面磨損量計算模型�；趯к墴崃︸詈蠑抵的M及磨損深度解析建立了最終剛度模型,結果顯示,上、下滾道接觸剛度在摩擦熱傳遞、熱彈接觸變形及磨損綜合作用下隨行程而呈現(xiàn)不同程度的非線性遞減。通過LMS振動測試完成剛度模型的頻域驗證,成功探測到導軌由于接觸剛度下降剛體模態(tài)由(2.36-6.58)k Hz遷移至(2.05-5.66)k Hz,并基于提出的剛度模型建立了更為精確的導軌剛體模態(tài)頻率解析式,實測頻率與解析值最大誤差為15.2%。同時,結果表明,摩擦熱和磨損效應對導軌剛度變化的影響具有時序性。將熱影響研究拓展至整機基礎結構,分析了環(huán)境熱波動下新型礦物鑄件材料機架的熱力學性能及結構靜態(tài)精度。通過平面度測試和線性模態(tài)分析驗證了此材料替代傳統(tǒng)材料應用于精密機床的可靠性。結果表明,礦物鑄件結構靜態(tài)剛度可滿足精密機床大型基礎構件50μm平面度的精度要求,其動力學特性優(yōu)于鑄鐵,模態(tài)特性略遜于天然花崗石,低階自然振動頻率高于90Hz,保證了其在系統(tǒng)典型激振頻率下的動力學穩(wěn)定性。基于有限元法推導了礦物鑄件結構溫度場解析方程,通過熱傳遞及熱力耦合數值模擬結合激光干涉儀測試,量化了礦物鑄件機架在外部熱源波動、表面對流及熱力耦合效應下的非線性變形機理,揭示了恒溫控制對保證大型構件在環(huán)境熱波動下結構精度的至關重要性。進一步將熱研究拓展至進給系統(tǒng),量化高精平臺在復雜熱環(huán)境下的熱力學行為及動態(tài)精度。通過建立結合部混合支撐下進給系統(tǒng)動力學微分方程,揭示了重心驅動的重要性。為避免孤立平臺結構,建立了包含完整進給系統(tǒng)的熱力耦合數值模型,考慮了電機熱、導軌摩擦熱及環(huán)境熱波動。通過動力學沖擊分析量化了平臺在熱力耦合作用下的非線性變形及動態(tài)偏擺機制,并通過激光干涉儀進行了驗證。結果顯示,平臺動態(tài)誤差隨環(huán)境溫升非線性遞增,溫變4°C-8°C,平均偏擺誤差達5.12-10.67μm/m,且保證高精平臺理想動態(tài)精度的溫度波動上限為4℃。同時,從電機多通道溫度測試和導軌熱通量解析發(fā)現(xiàn),外部環(huán)境熱波動是影響進給系統(tǒng)動態(tài)精度的最關鍵熱源,而非系統(tǒng)內部熱源。從全局角度定量研究了高精機床在真實工況下加工精度的變化機理。通過整機熱力耦合建模及求解,量化了系統(tǒng)在綜合熱源波動、接觸熱阻及熱力耦合效應下的溫度場分布及結構的非線性變形。結果表明,環(huán)境溫升5℃,平臺呈二階彎曲變形,顯著影響其動態(tài)精度�；谶\動結構的動力學沖擊熱力耦合數值模擬,得到了TCP(刀具中心)點在內、外部熱源及熱力耦合效應下的動態(tài)位置精度。數值和測試結果一致表明,孔位精度隨外界環(huán)境溫升而衰減,溫升5℃時,部分軸位已經無法達到25.4μm的孔位精度要求。通過微孔鉆實驗進一步分析了不同熱環(huán)境下機床動態(tài)鉆孔精度的CPK(制程能力指數)值及變化規(guī)律,再次揭示了環(huán)境熱波動對其自身加工精度的極端重要性。
[Abstract]:High speed, high precision CNC machine tool is an important factor affecting and restricting the level of electronic manufacturing industry and electronic information industry base supporting capacity. In recent years, along with the information, communications, medical, aerospace and other fields of electronic products to high function, high density and high reliability, the machining accuracy of NC machine tool, put forward higher requirements the efficiency and stability. The thermal error is the decisive factor affecting the dynamic high precision machining precision of the machine tool, the total error of 70%. therefore, to carry out research on engineering thermal error mechanism to solve the high precision machine tool exists is important technical bottleneck of poor thermal stability. The thermal and dynamic properties are complex temperature field in the structure of production the stress, comprehensive reflection of nonlinear deformation and thermo mechanical coupling effect between components, so the thermal phenomena cannot be isolated to study local system. This paper analyzes the machine system from a global perspective The internal structure of the unit and in the thermal coupling effect under static and dynamic accuracy characteristics and evolution, the main contents are as follows: the analysis of nonlinear stiffness of linear rolling guide. Based on Hertz contact theory, considering the contact elastic deformation and preload effect established rail initial stiffness model, quantization, initial stiffness of raceway the nonlinear change characteristics with loads. The contrary tendency ball differential sliding friction, elastic hysteresis and spin energy analysis, equivalent heat intensity calculation of the rolling interface, and Achard wear theory calculation model was established based on wear of rail contact interface. Numerical simulation and thermodynamic coupling rail wear depth analysis was established the final results show that the stiffness model based on lower raceway contact stiffness transfer in friction heat, thermal elastic contact deformation and abrasion with different degree of stroke The nonlinear decreasing vibration test by LMS. Complete the verification frequency stiffness model, successfully detected guide because the contact stiffness decreased by rigid mode (2.36-6.58) k Hz (2.05-5.66) k migrated to Hz, and the stiffness model is put forward based on a more rigid guide mode frequency analytical precision, the measured frequency with the analytical value of the maximum error is 15.2%. at the same time, the results show that the effect of friction heat and wear effect of track stiffness change with time. The effect of thermal expansion to the basic structure, the new type of mineral casting material under dynamic thermal environment frame thermodynamic properties and structural static analysis. The reliability of precision materials to replace conventional materials used in the precision machine tool is verified by the flatness measurement and linear modal analysis. The results show that the mineral casting structure static stiffness can meet the precision machine tool large foundation member 50 m flatness The precision, the dynamic characteristics of the modal characteristics were better than cast iron, natural granite, low order natural vibration frequency is higher than 90Hz, which in a typical vibration system under dynamic stability. The temperature field of mineral casting structure based on the finite element method is deduced by means of heat transfer and thermal mechanical coupling numerical simulation combined with laser interferometer testing, to quantify the mineral casting frame in external heat wave, the deformation mechanism of nonlinear surface convection and thermal coupling effect, reveals the temperature control to ensure the vital importance of large dynamic structure in the environment. The accuracy of thermal wave will further expand to the hot research feed system, thermodynamic behavior quantitative high precision platform in complex thermal environment and the dynamic precision. Dynamic differential equation of mixed feed system supported by establishing a connection, and reveals the importance of gravity driven. Avoid isolated platform structure, established the thermal mechanical coupling numerical model including complete feed system, considering the motor heat, friction heat and thermal environment fluctuation. Through dynamic impact analysis to quantify the nonlinear deformation and dynamic platform under thermo mechanical coupling deflection mechanism, and through the laser interferometer was verified. The results show that the platform the dynamic error with the environment temperature increasing, temperature of 4 DEG C-8 DEG C, the average yaw error reached 5.12-10.67 mu m/m, and ensure the maximum temperature fluctuation and high precision platform ideal dynamic accuracy is 4 DEG C. At the same time, found from the motor multi-channel temperature testing and guide heat flux analysis, thermal fluctuation is the external environment the pivotal effect of the drive system dynamic accuracy, rather than the internal heat source system. The change mechanism of processing in the real working condition of high precision precision machine tool research from a global perspective. Through the quantitative thermodynamic Ou Hejian Model and solution, quantitative fluctuation of system in heat deformation, thermal contact resistance and thermal coupling effect under the nonlinear temperature field distribution and structure. The results show that the environment temperature is 5 DEG C, platform two order bending deformation, significantly affect the dynamic precision. Dynamic motion of structure impact thermo mechanical coupled numerical simulation based on the obtained TCP (tool center point), the dynamic position precision of external heat source and thermal coupling effect. The numerical and test results show that the accuracy of hole position with the external environment temperature rise and decay, the temperature rise of 5 degrees, some axis has been unable to reach 25.4 mu m. Through the micro hole drilling hole position accuracy the further analysis of the machine tool dynamic precision drilling in different thermal environments CPK (process capability index) value and change the regulation, once again reveals the extreme importance of environmental thermal fluctuations on its machining precision.

【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：TG502.13

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