發(fā)布時(shí)間：2018-08-17 17:27

【摘要】：隨著驅(qū)動(dòng)技術(shù)的發(fā)展，機(jī)床電主軸已逐步成為現(xiàn)代機(jī)床與電氣系統(tǒng)之間結(jié)合的重要部件，它在數(shù)控機(jī)床發(fā)展中占有重要地位。車床手工裝卡時(shí)間在整個(gè)加工過(guò)程中占用比例較大。為了縮短工件裝卡時(shí)間、提高機(jī)床自動(dòng)化程度，設(shè)計(jì)制造帶有自動(dòng)夾取功能、用于加工小型盤類零件的專用機(jī)床，具有廣泛的應(yīng)用前景。機(jī)床電主軸具有結(jié)構(gòu)簡(jiǎn)單、電機(jī)直接驅(qū)動(dòng)主軸等優(yōu)點(diǎn)，是設(shè)計(jì)具有自動(dòng)夾取功能專用機(jī)床的首選主軸方案。自動(dòng)化專用機(jī)床電主軸的工作過(guò)程使其熱平衡過(guò)程處在有源傳熱與無(wú)源傳熱交替進(jìn)行的狀態(tài)。專用機(jī)床電主軸采用間歇工作制，減輕了主軸自身平均熱負(fù)荷的同時(shí)，也緩解了電主軸溫升問(wèn)題對(duì)加工精度影響。主軸加工工件時(shí)內(nèi)裝電機(jī)處于有源傳熱狀態(tài)，內(nèi)裝電機(jī)產(chǎn)生的銅耗和鐵耗通過(guò)各部件之間的熱傳遞散發(fā)出去；主軸停機(jī)夾取工件過(guò)程中，內(nèi)裝電機(jī)沒有損耗產(chǎn)生，各部件內(nèi)部?jī)?chǔ)存的熱能由于主軸內(nèi)外溫度差的存在而繼續(xù)進(jìn)行熱傳遞。因此有效的計(jì)算電主軸在自動(dòng)化專用機(jī)床實(shí)際加工過(guò)程中溫升狀態(tài)是電主軸設(shè)計(jì)和機(jī)床熱誤差補(bǔ)償?shù)年P(guān)鍵。 結(jié)合具有自動(dòng)上下料功能的卡盤倒置立式車床研發(fā)項(xiàng)目，，在對(duì)機(jī)床加工工況、電主軸散熱結(jié)構(gòu)及散熱過(guò)程詳細(xì)分析之后。以瞬態(tài)熱網(wǎng)絡(luò)法建立車床電主軸溫升計(jì)算模型，并用有限單元法進(jìn)行模擬，對(duì)比驗(yàn)證模型計(jì)算結(jié)果。對(duì)設(shè)計(jì)方案在多種模擬實(shí)際工況下進(jìn)行了溫升校核，并計(jì)算了主軸軸向熱變形。為了改善卡盤倒置立式車床加工精度，以間歇載荷下電主軸瞬態(tài)溫升計(jì)算為基礎(chǔ)提出一種熱誤差實(shí)時(shí)補(bǔ)償方法。最后以車床內(nèi)裝電主軸樣機(jī)為實(shí)驗(yàn)對(duì)象進(jìn)行模擬實(shí)際加工工況的溫升實(shí)驗(yàn)，驗(yàn)證溫升計(jì)算模型的正確性。 研究?jī)?nèi)容及結(jié)論包括以下幾個(gè)方面： （1）本文對(duì)立式車床的動(dòng)態(tài)加工過(guò)程、主要加工參數(shù)進(jìn)行了詳細(xì)分析，確定了在電主軸內(nèi)裝電機(jī)的類型及電氣參數(shù)，運(yùn)用有限單元法計(jì)算了車床電主軸設(shè)計(jì)過(guò)程中主軸剛度及固有頻率，進(jìn)而對(duì)設(shè)計(jì)方案中內(nèi)裝電機(jī)散熱結(jié)構(gòu)進(jìn)行分析，最終結(jié)合機(jī)床整體使用工況，確定了散熱方案為自然冷卻。對(duì)永磁同步主軸散熱過(guò)程進(jìn)行了詳細(xì)分析，利用分離變量法求解了定轉(zhuǎn)子非穩(wěn)定傳熱方程級(jí)數(shù)解，對(duì)后續(xù)確定邊界條件及求解方法提供理論基礎(chǔ)。 （2）應(yīng)用傳熱學(xué)理論以瞬態(tài)熱網(wǎng)絡(luò)法建立計(jì)算模型，分別計(jì)算了間歇載荷時(shí)高速輕載，低速重載等多種實(shí)際工況下電主軸內(nèi)部各部分溫升情況。用有限單元法對(duì)相同工況進(jìn)行分析，初步驗(yàn)證了熱網(wǎng)絡(luò)模型的計(jì)算結(jié)果。在多種模擬實(shí)際工況下對(duì)設(shè)計(jì)方案進(jìn)行了溫升校核，結(jié)果表明有限單元法計(jì)算結(jié)果比熱網(wǎng)絡(luò)法略高。 （3）應(yīng)用熱彈性力學(xué)及有限元理論，建立了基于熱結(jié)構(gòu)耦合的電主軸有限元分析模型，計(jì)算了車床電主軸在卡盤倒置立式車床實(shí)際加工過(guò)程中溫度場(chǎng)變化引起的軸向熱變形。 （4）對(duì)主軸加工時(shí)熱變形進(jìn)行了詳細(xì)分析，主軸徑向熱變形在允許范圍內(nèi)，軸向熱變形從加工開始直到主軸到達(dá)動(dòng)態(tài)熱平衡時(shí)持續(xù)增大。在加工單個(gè)零件時(shí)由于加工時(shí)間短主軸尚未發(fā)生較大熱變形，單個(gè)零件的加工精度在誤差允許范圍內(nèi)。自動(dòng)化機(jī)床加工整批零件時(shí)，后加工的零件將由于主軸熱變形造成精度超出誤差允許范圍。針對(duì)這種情況，提出了一種基于車床內(nèi)裝電主軸瞬態(tài)熱特性計(jì)算的誤差補(bǔ)償方法，以減小卡盤倒置立式車床主軸熱變形引起的軸向尺寸誤差。為車床內(nèi)裝電主軸應(yīng)用于各種不同工況的熱誤差預(yù)測(cè)和誤差補(bǔ)償提供了一種新方法。 （5）在不同轉(zhuǎn)速及負(fù)載轉(zhuǎn)矩下以車床電主軸樣機(jī)為研究對(duì)象，進(jìn)行了模擬自動(dòng)化加工過(guò)程的瞬態(tài)溫升實(shí)驗(yàn)。用實(shí)驗(yàn)數(shù)據(jù)與熱網(wǎng)絡(luò)模型對(duì)應(yīng)的計(jì)算值進(jìn)行對(duì)比，分析表明車床內(nèi)裝電主軸間歇載荷下熱傳遞模型計(jì)算結(jié)果在誤差允許范圍內(nèi)。在參數(shù)及邊界條件選擇正確的前提下，可以有效的計(jì)算車床電主軸在自動(dòng)化加工過(guò)程中的瞬態(tài)溫升。 綜上所述，本文主要應(yīng)用熱網(wǎng)絡(luò)法及有限單元法揭示了車床電主軸的結(jié)構(gòu)參數(shù)設(shè)計(jì)及間歇載荷對(duì)熱態(tài)性能的影響機(jī)理和規(guī)律，以車床電主軸溫升實(shí)驗(yàn)證實(shí)了理論計(jì)算結(jié)果在誤差允許范圍內(nèi)，為電主軸在卡盤倒置立式車床加工過(guò)程中熱誤差補(bǔ)償研究提供了理論基礎(chǔ)。
[Abstract]:With the development of drive technology, the motorized spindle of machine tools has gradually become an important part of the combination between modern machine tools and electrical systems. It plays an important role in the development of CNC machine tools. The machine tool motorized spindle has the advantages of simple structure and direct motor drive. It is the preferred spindle scheme for designing the machine tool with automatic clamping function. The working process of the motorized spindle of the automated machine tool makes its thermal balance excessive. The motorized spindle of the special machine tool adopts the intermittent working system, which reduces the average heat load of the spindle itself and alleviates the influence of the temperature rise of the motorized spindle on the machining accuracy. The heat transfer between the components is emitted; during the process of the spindle stopping and clamping the workpiece, there is no loss of the built-in motor, and the heat stored in the components continues to be transferred because of the temperature difference between the inside and outside of the spindle. The key of shaft design and thermal error compensation of machine tools.
Based on the research and development project of the chuck inverted vertical lathe with automatic loading and unloading function, the working condition of the lathe, the heat dissipation structure of the motorized spindle and the heat dissipation process are analyzed in detail. The calculation model of the temperature rise of the motorized spindle of the lathe is established by the transient thermal network method, and the results of the model are compared and verified by the finite element method. In order to improve the machining accuracy of the chuck inverted vertical lathe, a real-time thermal error compensation method is proposed based on the transient temperature rise calculation of the motorized spindle under intermittent load. Finally, the prototype of the motorized spindle installed in the lathe is used as the experimental object to simulate the actual addition. The temperature rise test of the working condition verified the correctness of the temperature rise calculation model.
The research contents and conclusions include the following aspects:
(1) In this paper, the dynamic machining process of the vertical lathe, the main processing parameters are analyzed in detail, the type of motor installed in the spindle and the electrical parameters are determined, the spindle stiffness and natural frequency in the design process of the spindle are calculated by the finite element method, and then the heat dissipation structure of the motor installed in the design scheme is analyzed. The heat dissipation process of permanent magnet synchronous spindle is analyzed in detail, and the unsteady heat transfer equation of stator and rotor is solved by the method of separation of variables, which provides a theoretical basis for determining boundary conditions and solving methods.
(2) Based on the theory of heat transfer, the transient heat network method is used to establish the calculation model, and the temperature rise of each part of the motorized spindle is calculated under various practical conditions, such as high speed, light load, low speed and heavy load. The results show that the finite element method is slightly higher than the thermal network method.
(3) Based on thermoelasticity and finite element theory, the finite element analysis model of the motorized spindle is established, and the axial thermal deformation of the motorized spindle caused by the change of temperature field in the actual processing of the chuck inverted vertical lathe is calculated.
(4) The thermal deformation of the spindle during machining is analyzed in detail. The radial thermal deformation of the spindle is within the allowable range, and the axial thermal deformation increases continuously from the beginning of machining until the spindle reaches the dynamic thermal balance. In order to reduce the axial dimension error caused by the thermal deformation of the spindle of a chuck inverted lathe, an error compensation method based on the calculation of the transient thermal characteristics of the spindle installed in the lathe is proposed. A new method for predicting and compensating the thermal errors of lathe with motorized spindle under various working conditions is provided.
(5) Taking the prototype of lathe motorized spindle as the research object under different rotational speeds and load torque, the transient temperature rise experiment of simulating the process of automatic machining was carried out. On the premise of choosing the correct parameters and boundary conditions, the transient temperature rise of lathe motorized spindle in the process of automatic machining can be calculated effectively.
In summary, this paper mainly uses the thermal network method and the finite element method to reveal the mechanism and law of the structure parameter design of the lathe motorized spindle and the influence of intermittent load on the thermal performance. The temperature rise experiment of the lathe motorized spindle confirms that the theoretical calculation results are within the allowable error range and the motorized spindle is in the process of the chuck inverted vertical lathe. Thermal error compensation provides a theoretical basis.
【學(xué)位授予單位】：沈陽(yáng)工業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TG51

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