【作者】 蒋永翔；

【导师】 唐委校；

【作者基本信息】 山东大学 ， 化工过程机械， 2007， 硕士

【摘要】 外圆磨削过程中，由于不稳定磨削产生的振动，导致加工工件尺寸精度、形位精度、表面粗糙度和表面波纹度现象的恶化。基于与XX机床厂合作课题“MGB1412×250型高精度外圆磨床动态优化”的研究，对该类型机床的磨削振动尤其是颤振抑制进行分析探讨，提高了外圆磨床的加工精度。通过对外圆磨床进行的结构动态特性分析和磨削过程的稳定性预测，完成了以稳定磨削条件下的高生产效率和高加工质量为优化目标的动态优化，探讨了设计、制造、检验、加工生产与维护的整个生命周期中的动态优化方法。本课题采用动态子结构法将结构及联接方式复杂的外圆磨床按各部件功能及其组合方式不同，划分为砂轮主轴系统、头架-主轴系统、尾架、砂轮架、滑鞍、工作台和床身等将相对简单的子结构，便于确保计算结果的准确性及进一步子结构动态优化的实施。在边界条件的确定上，通过动态试验频响函数法识别了刚度、阻尼等等效动力学参数，并利用试验测试结果修正边界条件，获得了接近真实工况的结构动态特性数值计算结果，为结构动态优化提供依据。在外圆磨削系统稳定性研究中，基于对磨削过程中颤振机理、特性的分析及切入磨、纵磨加工中颤振导致的不稳定磨削现象的研究，分别建立外圆切入磨及纵磨的工件颤振和砂轮颤振动力学模型，并通过对模型的求解分析预测颤振频率，建立适合外圆切入磨和纵磨特点的稳定性预测理论及稳定性判据，进而通过外圆磨削稳定性极限图解法分析磨床结构和磨削过程工艺参数对磨削稳定性的影响，提出外圆磨削稳定性的评价方法，为磨削稳定性的预测分析、动态优化及其工程应用提供理论依据和方法。设计并实施了MGB1412×250型高精度半自动外圆磨床的模态试验、空转试验和磨削动态试验。通过模态试验识别外圆磨床整机及各子结构的各阶固有频率，验证了外圆磨床结构动态特性分析的理论计算结果。对不同工艺参数匹配下的空转及磨削试验数据变化规律的分析，为磨削稳定性理论提供试验数据验证，此外，分析故障频率现象及其规律，获得了消除故障频率的减振方法。基于结构动态特性分析、稳定性理论研究及动态试验，采用结构动态优化结合磨削过程工艺参数动态优化的方法，对MGB1412×250型高精度半自动外圆磨床进行了动态优化以提高外圆磨床的动态特性，降低和消除了该磨床磨削振动引起的工件表面波纹度现象，提高了磨削精度。更多还原

【Abstract】 Vibration is an unfavorable dynamic phenomenon encountered in grinding operation. It influences the quality parameters of work pieces surface spoiling its dimension precision and surface roughness, resulting in surface waviness. As the cooperation with XX CNC Co.Ltd. in the "Research on dynamics optimization of MGB1412×250 high precision cylindrical grinding machine ", the grinding vibration suppressing especially chatter suppressing is analyzed. Structure dynamic analysis and stability predication is necessarily used to restrain vibration especially chatter and improve precision of grinding work pieces. Therefore, a new conception of stability optimization based on stable grinding of high production efficiency and precision is used in the whole life cycle of the design, manufacture, inspection, machining operation and maintenance.Sub-structure dynamic method is used to analyze grinding wheel- principal axis system, lathe hedd, tail stock, grinding wheel stock, saddle, workbench and lathe bed etc. The simplicity of analyzing its dynamic characteristics and the precision of numerical value calculation is guaranteed by dividing complicated grinding machine into pieces. The boundary conditions are determined by dynamic experiments, based on frequency-response function, the equivalent dynamic parameters of stiffness and damping are recognized which are compared and modified by the boundary conditions obtained in dynamic experiments. The numerical value calculation results used by sub-structure dynamic methods and boundary conditions recognition technique agree well with modal experiential results which lay the foundation of structure dynamic optimization.Stability investigation is based on displacement feedback regenerative chatter principle. Considering work piece regenerative chatter and grinding wheel regenerative chatter, the plunging grinding closed loop system dynamic model is set up. The traverse grinding dynamic model is also set up with the simplified of plunging grinding to the sum of plunging grinding. Using frequency-response function which is expressed by grinding parameters and structure parameters, the characteristic equations are calculated. The predicting method of stability criterion with respect to the rate of chatter waviness increase is proposed. In this way, the influence of grinding parameters to grinding stability is portrayed.Experiments of modal analysis are designed and carried out to investigate and validate the dynamics model, stability theory. With the modal, racing and grinding experiments, the nature frequencies calculated by numerical value calculation of the whole grinding machine and its sub-structures is validated. The matching of grinding parameters designed in racing and grinding experiments are used to validate stability theory. Experiments are also used to diagnose the experimental grinding machine, the faults leading to surface waviness as well as vibration eliminate methods are pointed out.Dynamic optimization technique in cylindrical grinding is based on structure dynamics, stability analysis and dynamic experiments with technique of structure dynamic modification and grinding parameter modification. As an example, dynamic optimization technique is used for MGB1412×250 high precision cylindrical grinding machine to improve its dynamic characteristics.更多还原