基于RCSA的主轴刀具系统刀尖点频响函数预测

发布时间：2018-05-17 20:50

本文选题：机床主轴 + 刀尖点频响函数　；参考：《大连理工大学》2016年硕士论文

【摘要】：发生在铣刀与工件接触面之间的再生颤振会导致铣削加工过程出现不稳定现象,降低工件表面质量和材料去除率,降低生产效率,甚至损坏刀具和机床主轴系统。抑制再生颤振已经成为机床稳定性主要研究方向。用来预测铣削加工稳定域的稳定性叶瓣图为抑制颤振的产生起到了指导作用。构建已知刀具组合方式的稳定性叶瓣图则需要刀尖点频响函数。因此,本文针对刀尖点频响函数预测过程中所涉及的动力学模型,耦合理论与预测方法等方面进行了研究。建立了铣削系统的动力学模型,并进行了模态实验。根据刀具与工件的刚性,将动力学模型分别划分为柔性刀具刚性工件与柔性刀具柔性工件铣削动力学模型；给出了基于锤击实验的模态分析法,获取了后续需要进行刀尖点频响函数预测的实验刀具前四阶固有频率。在分析响应耦合方法获取的机床主轴系统结构响应时,考虑了剪切力和转动惯量对计算结构响应的影响。主轴中的结构受力后变形复杂,响应耦合方法能全面地反映出结构的弯曲和扭转响应；与此同时,相比于采用Euler-Bernoulli模型获取的结构响应,考虑到剪切力和转动惯量的Timoshenko模型能够更准确地反应梁在受力情况下的弯曲与剪切变形。尤其是在主轴中长径比较低的梁部件和部件经装配后长径比降低的情况。提出一种将数值计算与敲击实验结合的刀尖点频响函数预测方法。通过对刀柄和测试刀具敲击实验,结合对测试刀具响应的数值计算结果,实现对刀具和刀柄结合面的参数识别。随后利用参数辨识的结果,综合对预测刀具响应的数值计算,从而实现对刀尖点频响函数的预测。此预测方法可以在保证精度的同时,减少重复敲击实验,实现刀尖点频晌函数的快速预测。最后,对刀尖点频响函数预测方法进行实验验证。预测的结果与直接通过敲击实验获得的频响函数具有很好的一致性,并且在频率和幅值上都较基于Euler-Bernoulli模型的预测结果更为精确,幅值上的精度提高尤为显著。通过实验验证了预测方法的有效性与精确性。
[Abstract]:The regenerative chatter between the milling cutter and the workpiece interface will lead to the instability of the milling process, reduce the surface quality of the workpiece and the material removal rate, reduce the production efficiency, and even damage the tool and the spindle system of the machine tool. Restraining regenerative flutter has become the main research direction of machine tool stability. The stable flaps used to predict the stable region of milling play a guiding role in suppressing flutter. The frequency response function of the tip point is required to construct the stable leaf flap plan of the known tool combination. Therefore, the dynamic model, coupling theory and prediction method involved in the prediction of the frequency response function of the knife tip are studied in this paper. The dynamic model of milling system is established and the modal experiment is carried out. According to the rigidity of tool and workpiece, the dynamic model is divided into two dynamic models: flexible tool rigid workpiece and flexible cutting tool flexible workpiece milling dynamics model, and the modal analysis method based on hammering experiment is given. The first four natural frequencies of the experimental tool which need to predict the frequency response function of the tool tip are obtained. The influence of shear force and moment of inertia on the structural response of the machine tool spindle system is considered in the analysis of the structural response obtained by the coupling response method. The deformation of the structure in the main shaft is complex, and the response coupling method can fully reflect the bending and torsional response of the structure, and at the same time, compared with the structural response obtained by the Euler-Bernoulli model, the coupling method can fully reflect the bending and torsional response of the structure. The Timoshenko model, which takes into account the shear force and the moment of inertia, can reflect the bending and shear deformation of the beam more accurately. In particular, the ratio of length to diameter of beam parts and components with low length and diameter is reduced after assembly. A method for predicting the frequency response function of knife tip is presented, which combines numerical calculation with percussion experiment. Based on the impact experiments of the tool handle and the test tool, and the numerical results of the response of the testing tool, the parameter identification of the tool and the joint surface of the tool holder is realized. Based on the result of parameter identification, the numerical calculation of predicting tool response is synthesized, and the frequency response function of tool tip is predicted. This prediction method can not only guarantee the accuracy but also reduce the repeated tapping experiments and realize the fast prediction of the frequency function of the knife tip. Finally, the prediction method of frequency response function of knife tip is verified by experiment. The predicted results are in good agreement with the frequency response function obtained from the percussion experiment, and are more accurate in frequency and amplitude than those based on Euler-Bernoulli model, especially in amplitude. The validity and accuracy of the prediction method are verified by experiments.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG659

【参考文献】