【作者】 张杨广；

【导师】 刘战强；

【作者基本信息】 山东大学 ， 机械制造及其自动化， 2013， 硕士

【摘要】 高速铣削加工在工业生产中已经得到了越来越广泛的应用,而制约高速铣削加工效率的一个重要问题就是颤振。获取高速铣削系统尤其是“主轴一刀柄一刀具”系统的动力学特性参数是对颤振现象进行准确预测的关键所在。刀具是铣削加工系统中最活跃的因素,因此有必要系统地分析刀具几何参数对“主轴一刀柄一刀具”系统动力学特性的影响。本文研制应用于铣削系统模态参数测试的电子冲击力锤,并且在建立整体立铣刀几何模型和模态分析模型的基础上,对立铣刀的动态特性进行实验和仿真分析,重点研究立铣刀几何参数对铣削系统动态特性的影响规律,为立铣刀结构优化设计提供理论基础和技术支持。首先,针对铣削系统模态测试中人工锤击法的不足,研制一种工作台式电子冲击力锤测试装置。该装置利用电磁原理,通过控制牵引式电磁铁的通/断电,使牵引力带动冲击力锤实现对被测对象的冲击,并对BT40刀柄、立铣刀杆进行冲击测试实验。该装置能够产生重复性好、可变大小的冲击力,可以取代人工力锤,并且适用于切削刀具系统端点频率响应函数的测试。其次,建立整体立铣刀的三维几何模型。在Pro/E软件中建立立铣刀的三维实体模型,导入到有限元分析软件ANSYS Workbench中进行模态分析,并通过刀具模态参数测试装置对所建立的模型进行实验分析,验证所建立的三维模型的正确性。然后,采用响应耦合子结构分析法(RCSA法)并结合模态试验,获得刀具与刀柄/主轴之间的接合面特性参数,并对铣削系统刀尖点频响函数进行预测。另外,模态试验结果表明,随着刀具悬伸长度的增大,铣削系统一阶固有频率和模态刚度逐渐减小,一阶阻尼比逐渐增大。最后,在立铣刀几何模型的基础上,采用RCSA法研究立铣刀几何参数(刀齿数、刀具直径、刀槽芯部直径以及螺旋切削刃长度)的变化对铣削系统动态特性参数的影响规律。更多还原

【Abstract】 High speed milling (HSM) has been widely used in industry. In the HSM process, a problem known as chatter is frequently encountered. In order to predict chatter in the milling process as accurately as possible, the dynamics of the spindle-tool holder-tool (STT) system need to be known since they are important for the HSM process. As the tool is the most active factor in the milling process, it is necessary to analyze the effect of cutter geometric parameters on the dynamics of STT system. An electric impact hammer which can be used in the modal test of milling systems is developed in this dissertation. A method with combination of experiments with computer simulation is proposed to study the effects of end mill geometric parameters on milling system dynamics. The research could provide a theoretical basis for optimizing and designing the geometric parameters of end mills.In the process of experimental modal analysis, there are many uncertainties by using manual hammer impacting. In order to overcome these difficulties, a bench-type electric impact hammer is developed. It is composed of a workbench, a controller, a trigger, a switch power and an actuator. When the solenoid is energized, it creates an electromagnetic field that causes the ferrous core mass to accelerate. Because the impact force can be changeable and repeatable, so the electric impact hammer may take the place of manual hammer, and it can be used in the modal parameters test of many machining systems.The three-dimensional geometric model of end mill is established. In this dissertation, a3D model which has the same geometric parameters with actual end mill is established using the three-dimensional software Pro/E and verified by experimental modal analysis.A method combined modal experiment with receptance coupling substructure analysis (RCSA) is proposed to predict the tool-point FRF, and the stiffness/damping coefficients for the X direction collet connection between the tool and holder/spindle is validated. It lays a theoretical foundation for simulation analysis. Moreover, the modal parameters of milling systems with different tool overhang length are tested by experimental modal analysis. The results show that, as the tool overhang length are growing, the first-order natural frequency and modal stiffness are decreasing, while the damping ratio is increasing.The method of RCSA is used to study the effects of geometric parameters of end mill including tooth number, tool diameter, core diameter of the flute and flute length on the dynamics of the high speed milling system.更多还原