【作者】 罗红平；

【导师】 周志雄；

【作者基本信息】 湖南大学 ， 机械制造及其自动化， 2002， 硕士

【摘要】 本论文针对曲轴类零件的现有磨削加工方法中存在的定位误差大、加工效率低、设备投资多、厂房投入大、调整时间长、表面质量难以保证等缺陷，研究了一种新型高效的磨削原理——切点跟踪磨削法来一次装夹依次磨出曲轴的主轴颈和连杆颈，对于切点跟踪磨削理论和保证实现该磨削原理的若干关键技术作了初步的探讨。论文首先通过对切点跟踪磨削运动开展理论分析，建立了恒磨除率磨削条件下切点跟踪磨削法的运动模型，得出了运动误差的变化规律及其数控补偿的方法；其次针对切点跟踪磨削运动时曲轴旋转与砂轮往复直线跟踪运动联动所形成的特殊曲线的数控插补，研究了专门的插补算法及相应的控制策略；然后，对切点跟踪磨削过程中由于磨削过程中曲轴刚性的不足而产生的工件刚度误差及其补偿方法进行了详细的分析，同时讨论了砂轮半径变化、砂轮中心安装高度、磨削力、连杆颈磨削加工尺寸与计算数控程序时的尺寸不一致等对加工精度的影响规律；在上述理论分析的基础上，对切点跟踪磨削原理开展了试验研究，对切点跟踪磨削的运动方式进行了验证，在试验用磨床上实际加工出了曲轴的连杆颈。同时测量分析了不同角度上的曲轴刚度大小及其分布规律。最后，在上述理论分析与试验研究的基础上，对切点跟踪磨削运动状态和加工过程的分析进行了初步的计算机仿真研究。更多还原

【Abstract】 Conventionally, crankshafts have to be ground using several positioning and clamping operations because of the differences in axes orientations of the journal and the crankpin. In this operation, there are many problems such as relatively excessive errors of positioning and clamping, low productivity, large investment of equipment and workshops, long period in the adjustment of the machine tool and fixtures and poor surface finish of the ground part etc. To help with conquering these mentioned shortcomings, a new grinding principle named grinding of tracing tangent point is studied, which allows both crankpin and journal of the crankshaft to be ground in only one positioning and clamping operation. Theory of grinding of tracing tangent point and some key techniques in the realization and application of this new method are focused on. At first, a mathematical model of motion in the grinding of tracing tangent point is established according to the principle of constant removal rate of grinding based on the analyses of the grinding motion. Taking the characteristics of the motion model into carefully considered, the variation law of the machining error caused by tangential point tracing and its NC compensation methods are presented. Secondly, the NC interpolation algorithms of the special curve, which is formed by the rotational motion of crankshaft and to-and-fro motion of grinding wheel in the grinding of crankpin, and a corresponding controlling strategy of interpolation are studied. Then, the stiffness-error caused by the elasticity displacement of crankshaft because of its poor rigidity and the grinding forces etc and the error compensation method are preliminary analyzed, at the same time, factors which may cause the machining error hi the processiiof grinding, such as the variation of diameters of grinding wheel, the deviation of the height between the center of grinding wheel and the rotational center of crankshaft, grinding forces, the difference between the real radius of crankpin and the one used to calculate the motion data for CNC, are took into account for the error analyses. Based on these analyses, experimental study is carried out. The correctness of the motion model is verified by the realization of this new principle for grinding of tracing tangent point on the grinding machine tool. The stiffness of crankshaft is measured and its characteristics are analyzed. Finally, based on theoretical and experimental studies mentioned above, preliminary researches on the computer simulation concerning the motion state and machining process of grinding tangential point tracing are carried out.更多还原