發(fā)布時(shí)間：2018-09-05 18:58

【摘要】：機(jī)床主軸系統(tǒng)的高精度主要受主軸軸承的預(yù)緊狀態(tài)和熱態(tài)特性穩(wěn)定性的影響。分析機(jī)床主軸系統(tǒng)在工作時(shí)的溫升和熱變形等熱特性是提高數(shù)控機(jī)床加工精度的關(guān)鍵,且能有效改進(jìn)數(shù)控機(jī)床產(chǎn)品的性能。主軸系統(tǒng)中的軸承摩擦熱是主要的內(nèi)部熱源,軸承摩擦發(fā)熱使得主軸系統(tǒng)中各個(gè)部件之間出現(xiàn)不同的溫升,而溫升又引起各部件的熱膨脹,進(jìn)而導(dǎo)致主軸產(chǎn)生熱位移。為了進(jìn)一步研究機(jī)床主軸系統(tǒng)各部件之間溫度隨時(shí)間變化的規(guī)律與其自身熱變形的變化特征,本文以MGK7120×6高精度臥軸矩臺平面磨床為研究對象,對其砂輪主軸-軸承系統(tǒng)進(jìn)行了溫度場與熱變形的仿真,并對主軸系統(tǒng)進(jìn)行了溫度測量試驗(yàn)以驗(yàn)證溫度場仿真的正確性。本文主要研究工作如下:(1)基于滾動(dòng)軸承熱態(tài)特性理論,對軸承的摩擦起因與摩擦力矩進(jìn)行了詳細(xì)介紹與計(jì)算。以傳熱學(xué)理論為基礎(chǔ),對具有不同導(dǎo)熱系數(shù)的物質(zhì)之間的三種基本傳熱模式做了理論闡釋與分析,且進(jìn)一步總結(jié)了傳熱分析的四種分析方法。(2)基于溫度場熱傳導(dǎo)與邊界條件理論,對主軸-軸承系統(tǒng)進(jìn)行了穩(wěn)態(tài)和瞬態(tài)的溫度場仿真計(jì)算。從穩(wěn)態(tài)溫度場仿真結(jié)果分析了主軸沿軸線方向上的溫度分布規(guī)律,且改變主軸的轉(zhuǎn)速后得到了不同轉(zhuǎn)速下軸承部件的溫度變化。從瞬態(tài)溫度場仿真結(jié)果分析了軸承滾子與內(nèi)外圈滾道溫度隨時(shí)間的變化規(guī)律,進(jìn)一步得到了時(shí)間t=600s、1800s、3600s和4800s時(shí)的主軸沿軸線方向的溫度分布曲線對比圖。(3)基于Hertz彈性接觸理論,對滾動(dòng)軸承的應(yīng)力與變形進(jìn)行了計(jì)算公式的分析。根據(jù)熱-結(jié)構(gòu)耦合分析理論且在溫度場仿真的基礎(chǔ)上,對主軸-軸承系統(tǒng)進(jìn)行了熱-結(jié)構(gòu)耦合分析。由仿真得到的結(jié)果有:軸承滾子表面熱應(yīng)力分布為橢圓形狀,且與Hertz彈性接觸應(yīng)力的描述相同;建立軸承內(nèi)外圈沿圓周方向的路徑,得到軸承內(nèi)外圈在徑向、切向與軸向三個(gè)方向的熱位移大小,且進(jìn)一步得出了軸承內(nèi)外圈在三個(gè)方向的熱位移變化形狀;最后建立主軸沿軸線方向的路徑,得到了主軸在徑向、切向與軸向三個(gè)方向的熱位移與熱應(yīng)力的變化規(guī)律。(4)針對主軸-軸承系統(tǒng)溫度場仿真結(jié)果,對MGK7120×6高精度臥軸矩臺平面磨床砂輪主軸系統(tǒng)進(jìn)行了溫度測量試驗(yàn),以此驗(yàn)證主軸-軸承系統(tǒng)溫度場仿真的正確性。改變主軸轉(zhuǎn)速,重復(fù)試驗(yàn),得到了轉(zhuǎn)速與熱平衡時(shí)間兩者之間的關(guān)系。
[Abstract]:The high accuracy of machine tool spindle system is mainly affected by the preload state and thermal characteristic stability of spindle bearing. The analysis of the temperature rise and thermal deformation of the spindle system is the key to improve the machining accuracy of the NC machine tool, and the performance of the CNC machine tool product can be improved effectively. The friction heat of bearing in spindle system is the main internal heat source. The friction heat of bearing causes different temperature rise among the parts of spindle system, and temperature rise causes the thermal expansion of each component, which leads to the thermal displacement of spindle. In order to further study the variation of temperature with time between parts of machine tool spindle system and the variation characteristics of its own thermal deformation, this paper takes MGK7120 脳 6 high-precision horizontal grinding machine with lying shaft moment table as the research object. The temperature field and thermal deformation of the spindle bearing system of the grinding wheel are simulated, and the temperature measurement test of the spindle system is carried out to verify the correctness of the temperature field simulation. The main work of this paper is as follows: (1) based on the theory of hot state characteristic of rolling bearing, the friction cause and friction moment of bearing are introduced and calculated in detail. Based on the theory of heat transfer, three basic heat transfer modes between materials with different thermal conductivity are theoretically explained and analyzed. Furthermore, four methods of heat transfer analysis are summarized. (2) based on the theory of heat conduction and boundary conditions of temperature field, the steady and transient temperature field simulation of spindle bearing system is carried out. Based on the simulation results of steady state temperature field, the temperature distribution of the spindle along the axis is analyzed, and the temperature change of bearing parts under different rotational speeds is obtained by changing the rotation speed of the spindle. From the simulation results of transient temperature field, the temperature variation law of bearing roller and inner and outer ring raceway with time is analyzed, and the temperature distribution curves of spindle along axis direction at time t ~ (600s) ~ 1800s ~ (36) s) and 4800s are further obtained. (3) based on Hertz's elastic contact theory, The stress and deformation of rolling bearing are analyzed. Based on the thermal-structural coupling analysis theory and temperature field simulation, the thermal-structural coupling analysis of the spindle bearing system is carried out. The results obtained from the simulation are as follows: the thermal stress distribution on the bearing roller surface is elliptical, which is the same as the description of the Hertz elastic contact stress, the path of the inner and outer ring of the bearing along the circumferential direction is established, and the radial direction of the inner and outer ring of the bearing is obtained. The magnitude of the thermal displacement in the tangential and axial directions, and the shape of the thermal displacement of the inner and outer rings of the bearing in the three directions are further obtained. Finally, the path of the spindle along the axis is established, and the radial direction of the spindle is obtained. The variation of thermal displacement and thermal stress in three directions of tangential and axial direction. (4) according to the simulation results of temperature field of spindle bearing system, the temperature measurement test of MGK7120 脳 6 high precision horizontal grinding wheel spindle system for horizontal grinding machine is carried out. The correctness of temperature field simulation of spindle bearing system is verified. The relationship between rotational speed and heat balance time is obtained by changing the spindle speed and repeating the test.
【學(xué)位授予單位】：湘潭大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG596

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