凸轮轴高速磨削加工质量影响因素分析及关键技术研究

发布时间：2018-03-04 15:19

本文选题：凸轮轴磨削　切入点：加工质量　出处：《湖南大学》2016年博士论文　论文类型：学位论文

【摘要】：凸轮轴作为汽车、内燃机等行业的一种量大面广的关键零部件,其精度和质量稳定性直接影响到发动机的质量、寿命、废气排放和节能。随着能源危机的爆发以及新标准的施行,如何提高加工质量和加工效率是凸轮轴加工亟待解决的问题。为了保证凸轮轴的加工质量和加工效率,一般采用高性能凸轮轴数控磨床对其进行高效精密磨削加工。但是由于凸轮轴属于细长杆件,其刚性较差,同时轮廓型面复杂给磨削加工带来极大困难。本文以凸轮轴高速数控磨削加工为研究对象,进行凸轮轴磨削加工质量的影响因素分析及关键技术研究,在凸轮轴原始升程数据拟合优化、多圈磨削减少弹性退让、磨削稳定性分析与颤振抑制、工件转速优化、磨削加工误差分析与补偿等提高磨削加工质量的关键技术上形成突破,解决当前凸轮轴磨削加工中存在较大的原始升程数据测量误差、砂轮架进给弹性退让、磨削振动、磨削轮廓误差等问题。本文所做的研究工作内容主要包括:1)分析了凸轮轴磨削加工方式和工艺特点,对包含测量误差的原始离散凸轮升程数据进行三次样条函数插值法光顺,实现凸轮轴原始升程数据的拟合优化;在近似恒线速度数学模型的基础上,介绍了凸轮轴X-C轴联动数控磨削工艺流程。2)建立了凸轮轴磨削法向磨削力的数学模型,开展了磨削力和砂轮弹性退让位移实验研究;探讨了凸轮轴在不同转角、磨削深度及磨削圈数的弹性退让规律;通过多圈进给磨削减少了砂轮弹性退让。通过动刚度测试对凸轮轴磨床各主要部件的共振频率和临界转速进行分析,找出了机床加工过程中整机动刚度的主要薄弱环节,并对这些薄弱环节提出了优化措施。3)建立了凸轮轴高速磨削过程的动力学模型,分析了凸轮轴磨削加工的稳定性区域与不稳定性区域;通过模态分析求解磨削工艺系统的固有振型与固有频率,得到其薄弱环节;结合稳定性叶瓣图、系统薄弱环节和控制理论提出了相关的抑振方法。4)建立了凸轮轴磨削系统的Simulink仿真模型,得到凸轮轴高速磨削加工的临界磨削深度,验证了变速磨削的抑振效果;通过实验研究了磨削工艺参数对加工波纹度和粗糙度的影响规律,验证了稳定性叶瓣图的正确性,得到了凸轮轴高速磨削的最优速比和最佳砂轮线速度区间。5)分析发现凸轮轴X-C轴联动恒线速度磨削中,某些凸轮转角区间的砂轮架进给速度、加速度、加加速度超出砂轮架进给伺服系统允许的最大值;基于砂轮架进给不同加速方式的计算模型对该区间工件主轴转速进行积分反求,替换该区间的工件主轴转速并进行整体的三次样条曲线拟合;通过工件主轴转速优化前后的对比实验,验证了凸轮工件主轴转速优化方法的正确性。6)分析了凸轮升程与轮廓在磨削误差方面的变化趋势;建立了凸轮虚拟升程的构建模型及其最小二乘多项式拟合的光顺算法,建立了凸轮轴X-C轴联动磨削升程误差分析与补偿模型;利用误差补偿处理后的虚拟升程进行凸轮轴磨削加工实验,验证了模型的正确性。
[Abstract]:As the key parts of automobile camshaft, a large volume of internal combustion engine industry wide, the precision and stability of quality directly affects the quality of life of the engine, exhaust emission and energy saving. With the outbreak of the energy crisis and the implementation of new standards, how to improve the machining quality and machining efficiency is the Camshaft Machining urgent the problem. In order to ensure machining quality and efficiency of the camshaft by high performance camshaft CNC grinding machine for high precision grinding on it. But because the camshaft belongs to the slender rods, the less rigid, with complex shape contour grinding to bring great difficulties. In this paper, high speed CNC grinding for camshaft study of cam grinding quality influence factor analysis and key technology research, in the original cam lift data fitting optimization, multi circle grinding less elastic Yield analysis and inhibition of grinding chatter stability, workpiece speed optimization, machining error analysis and compensation to improve the formation of a breakthrough key technology of grinding quality, solve the camshaft grinding in the presence of the original lift measurement error is large, the grinding wheel grinding vibration, elastic yielding, grinding contour error. Research the main works of this paper include: 1) analysis of the camshaft grinding mode and process characteristics, three spline interpolation smoothing process of original discrete data cam contain measurement errors rise, realize the optimization of camshaft lift fitting original data; based on the approximate mathematical model of constant line speed on the camshaft, X-C axis NC grinding process.2) established a mathematical model of cam shaft grinding method to the grinding force, grinding force and grinding wheel to carry out elastic yielding a Experimental study on shift; cam shaft at different rotation angles, grinding depth and grinding of elastic yielding turns; through feed grinding wheel ring reduces the elastic yielding. Through the analysis of the dynamic stiffness test of the resonance frequency of the main components of the camshaft grinder and critical speed, find out the main weak links in the machining process the dynamic stiffness, and the optimization measures of.3 of these weak links) established a dynamic model of cam shaft high speed grinding process, analysis of the regional stability region of camshaft grinding and instability; analysis of natural vibration mode and natural frequency for the grinding process system through the modal, the combination of weak links; the stability lobes diagram, system of the weak link and control theory put forward.4 method in vibration suppression related) Simulink simulation model was established for camshaft grinding system, get the camshaft speed The critical grinding depth of grinding, verify the vibration suppression effect of variable speed grinding; grinding process parameters through the experimental study on machining waviness and roughness were investigated, verified the stability lobes, the optimal ratio of the camshaft speed grinding wheel speed and the best interval.5) analysis camshaft X-C axis constant linear velocity grinding, the grinding wheel speed, some cam angle interval acceleration, jerk beyond the grinding wheel feed servo system of the maximum allowed value; the grinding wheel based on different speed computation model for the range of workpiece spindle speed reverse integral, replace the workpiece spindle speed range and the whole three spline curve fitting; through the contrast experiment before and after the workpiece spindle speed optimization, validate the.6 cam spindle speed optimization method) points Analysis of the changing trend of cam lift and contour error in grinding cam; virtual lift model and least square polynomial fitting smoothing algorithm is established, a cam shaft X-C axis grinding lift error analysis and compensation model; for camshaft grinding experiment using virtual lift error compensation after treatment and verify the correctness of the model.

【学位授予单位】：湖南大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG580.6

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