本文選題：漸開線齒輪 + 混合彈流潤滑��； 參考：《北京理工大學(xué)》2014年博士論文

【摘要】：漸開線斜齒輪因傳動平穩(wěn)、承載能力強被廣泛應(yīng)用于高速重載傳動。隨著傳動系統(tǒng)對轉(zhuǎn)速和轉(zhuǎn)矩的大幅度提高，斜齒輪傳動的嚙合平穩(wěn)性、效率特性及疲勞壽命等問題成為高速重載齒輪研究的重點和熱點。在高速大功率運行工況下，齒輪傳動表現(xiàn)出強非線性動力學(xué)特征。齒面在大范圍變滑滾比狀態(tài)下作高速剪切運動并產(chǎn)生瞬時高溫，導(dǎo)致潤滑油粘度大幅度降低，油膜厚度顯著減小，潤滑狀態(tài)復(fù)雜多變。本文全面考慮了漸開線斜齒輪在混合潤滑狀態(tài)下的彈流潤滑特性、熱效應(yīng)以及摩擦學(xué)特性與動力學(xué)行為的耦合關(guān)系，建立了齒輪的摩擦動力學(xué)模型；考慮殘余應(yīng)力和硬度梯度的影響以及裂紋在不同階段的生長機制建立了齒輪接觸疲勞壽命的全過程預(yù)估模型。 本文首先建立了嚙合接觸區(qū)二維有限長線接觸混合彈流潤滑模型，基于最小彈性勢能原理確定了低速穩(wěn)態(tài)工況的載荷分布規(guī)律，并對彈流潤滑模型進行數(shù)值求解，獲得了接觸區(qū)的穩(wěn)態(tài)潤滑特性。在求解過程中，采用Reynolds方程的統(tǒng)一差分格式解決了混合彈流潤滑中粗糙峰接觸區(qū)的判定問題，應(yīng)用多重網(wǎng)格積分法加速了表面彈性變形的計算，并對多重網(wǎng)格法和Gauss-Seidel松弛迭代法聯(lián)立求解，獲得了接觸區(qū)的潤滑特性，揭示了齒面粗糙峰的峰值、方向相關(guān)特征和分布密度等因素對潤滑特性的影響規(guī)律。 當(dāng)齒輪在高速大轉(zhuǎn)矩工況下工作時，由于潤滑油膜內(nèi)部的高剪切作用以及混合潤滑狀態(tài)下粗糙峰間的摩擦剪切作用，接觸區(qū)將產(chǎn)生大量的熱。在彈流潤滑狀態(tài)下，入口區(qū)的剪切熱將降低潤滑劑的粘度，并導(dǎo)致由卷吸速度帶入接觸區(qū)的油量減少，從而使油膜厚度減薄。為了對齒面進行熱分析，將能量方程、移動點熱源法和熱流分配系數(shù)相結(jié)合，建立了齒面溫升模型，并與彈流潤滑方程相耦合，通過求解獲得了油膜中層溫升和兩齒面的溫升分布特征，進而揭示了熱流在齒面不同位置的傳導(dǎo)規(guī)律。 在實際運轉(zhuǎn)中，尤其在高速工況下，由于齒形和裝配誤差的存在，以及油膜的瞬態(tài)擠壓效應(yīng)，齒輪嚙合副在運動過程中將不可避免地產(chǎn)生動態(tài)傳遞誤差，進而引起載荷沖擊和振動。為了深入剖析潤滑特性與動力學(xué)行為的耦合關(guān)系，綜合考慮嚙合剛度的時變特性、油膜瞬態(tài)擠壓效應(yīng)，齒面形貌特征以及摩擦轉(zhuǎn)矩對動力學(xué)行為的影響，建立了漸開線斜齒輪的摩擦動力學(xué)模型。在數(shù)值求解過程中，建立了油膜變形量的解析模型，實現(xiàn)了動力學(xué)方程與彈流潤滑方程的解耦，以相對線位移滿足嚙合周期性的假設(shè)為依據(jù)，確定了動力學(xué)方程的邊界約束條件。對摩擦動力學(xué)模型進行迭代求解，獲得了嚙合過程中動態(tài)嚙合力的變化特征以及接觸區(qū)油膜壓力和溫升分布的動態(tài)變化過程，揭示了動態(tài)工況下斜齒輪接觸區(qū)的潤滑規(guī)律。 從齒輪失效形式來看，點蝕、剝落等接觸疲勞失效是最常見的失效形式，其失效機理較為復(fù)雜，與基體材料的晶體組織結(jié)構(gòu)、材料缺陷以及局部應(yīng)力分布有關(guān)。本文針對滲碳淬火齒輪的表面材料屬性，考慮殘余應(yīng)力和硬度梯度的影響，以次表面最大剪切應(yīng)力為評價參數(shù)，基于風(fēng)險疲勞累積理論建立了裂紋萌生壽命模型，用以預(yù)測沿齒面深度方向微裂紋的萌生位置和形核壽命。在裂紋擴展壽命模型中，，考慮裂紋在晶粒內(nèi)部的非線性擴展規(guī)律以及相鄰晶粒間的非連續(xù)擴展特征，建立了短裂紋擴展模型。綜合考慮疲勞裂紋擴展速率的不同階段，建立了長裂紋擴展的統(tǒng)一方程，進而完成了對齒輪接觸疲勞壽命的預(yù)估。
[Abstract]:The involute helical gear is widely used in high speed heavy load transmission because of its smooth transmission and strong bearing capacity. With the great improvement of the speed and torque of the transmission system, the meshing stability, efficiency characteristics and fatigue life of the helical gear transmission have become the focus and hot spot in the research of high speed heavy load gear. The wheel transmission shows strong nonlinear dynamic characteristics. The tooth surface performs high speed shear movement and produces instantaneous high temperature under the state of large range slip ratio. The viscosity of lubricating oil is greatly reduced, the thickness of oil film decreases significantly, and the lubrication state is complex and changeable. The elastohydrodynamic lubrication characteristics of involute helical gear in mixed lubrication state are fully considered in this paper. The thermal effect, the coupling relationship between the tribological characteristics and the dynamic behavior, the friction dynamic model of the gear is established, and the full process prediction model of the gear contact fatigue life is established by considering the influence of the residual stress and the hardness gradient and the growth mechanism of the crack in different stages.
In this paper, a two dimensional finite long line contact hybrid elastohydrodynamic lubrication model is established. Based on the principle of minimum elastic potential energy, the load distribution law of the low speed steady state is determined. The elastohydrodynamic lubrication model is solved numerically to obtain the steady state lubrication characteristics of the contact area. The unified difference of Reynolds equation is adopted in the solution process. The determination of the contact area of the rough peak in mixed elastohydrodynamic lubrication is solved by the fractional format. The multi grid integration method is applied to accelerate the calculation of the elastic deformation of the surface. The lubrication characteristics of the contact area are obtained by the simultaneous solution of the multigrid method and the Gauss-Seidel relaxation iteration method. The peak of the rough peak, the direction correlation feature and the distribution density are revealed. The influence of degree and other factors on the lubrication characteristics.
When the gear is working at high speed and high torque, the contact zone will produce a lot of heat due to the high shear inside the lubricating oil film and the friction shear between the rough peaks in the mixed lubrication state. In the elastohydrodynamic lubrication state, the shear heat of the entrance area will reduce the viscosity of the lubricant and lead to the oil from the entrainment velocity into the contact area. In order to make the thickness of the oil film thinner, the temperature rise model of the tooth surface is established by combining the energy equation, the moving point heat source method and the heat flow distribution coefficient, and the temperature rise of the middle layer of the oil film and the temperature rise distribution of the two tooth surface are obtained by solving the equation of the energy equation, the moving point heat source method and the heat flow distribution coefficient, and the heat flow is revealed in the tooth surface. The law of conduction in different positions.
In the actual operation, especially in high speed conditions, due to the existence of tooth shape and assembly error and the transient extrusion effect of oil film, the gear meshing pair will inevitably produce dynamic transfer error in the process of motion, and then cause the load impact and vibration. Considering the time-varying characteristics of the meshing stiffness, the transient extrusion effect of the oil film, the profile of the tooth surface and the influence of the friction torque on the dynamic behavior, the dynamic model of the involute helical gear is established. In the numerical solution, the analytical model of the deformation of the oil film is established, and the decoupling of the dynamic equation and the elastohydrodynamic lubrication equation is realized. On the basis of the assumption that the line displacement satisfies the meshing periodicity, the boundary constraint conditions of the dynamic equation are determined. The dynamic variation of the dynamic meshing force in the meshing process, the dynamic changing process of the oil film pressure and the temperature rise distribution in the contact area are obtained by iterative solution of the friction dynamic model, and the contact gear contact under dynamic conditions is revealed. The law of lubrication in the area.
From the form of gear failure, contact fatigue failure, such as pitting and peeling, is the most common failure form. Its failure mechanism is more complex, which is related to the crystal structure, material defects and local stress distribution of the matrix material. In this paper, the effects of the surface material properties of carburized quench gear and the influence of residual stress and hardness gradient are taken into consideration. The maximum shear stress is the evaluation parameter. Based on the risk fatigue accumulation theory, the crack initiation life model is established to predict the initiation position and the nucleation life of the micro cracks in the depth of the tooth surface. In the crack propagation life model, the nonlinear propagation law of the crack in the grain and the discontinuous expansion between the adjacent grains are considered. Characteristics, a short crack propagation model is established. Considering the different stages of fatigue crack growth rate, a unified equation for long crack propagation is established, and then the fatigue life of gear contact is estimated.
【學(xué)位授予單位】：北京理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TH132.413

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