Analysis On Dynamics Of Turning And Grinding Machine Tool

With the development of high speed, high accuracy and new industrialization of CNC machine tool, less-freedom machine tools get their attentions. For high speed and high accuracy machining, dynamic performance of machine tool is the key topics that must be considered. Besides the inherent characteristics of the structure, the dynamic performance of machine tool is more influence by the combination of surface characteristics. This paper introduces the influence of the whole machine by bearing surface and linear rolling guide surface.We study on the turning and grinding combined machine tool which belongs to the Mechanical Engineering and Automation academic, Northeastern University. Turning and grinding combined machine tool is composed of machine tool bed, parallel mechanism, and spindle box and so on. On the basis of3D solid model and finite model, this paper introduces the dynamic performance of key components, joint surface and the whole machine.Firstly, this paper introduces the dynamic of key component. We get the first10steps natural frequency and modal mode shape of spindle system, linear rolling guide and parallel mechanism, as well as the response of spindle in the harmonic force excitation. Compare the cases of consider joint surface factors and do not consider joint surface factors, we find in the former situation, natural frequency is higher, and modal mode shape do not include relative vibration. Refer to related reference and experiment data, the result which consider joint surface factors approach true value.Secondly, this paper uses spring-damping unit COMBIN14to simulate joint surface. We establish the spring-damping model of typical joint surface—bearing surface and linear rolling guide surface, and parameter is also given.Last, this paper introduces the dynamic performance of the whole machine, mainly the modal analysis. We get the natural frequency and principal mode. The study point out the weaknesses of machine tool:spindle stiffness is insufficient, parallel mechanism stiffness is insufficient, machine bed stiffness is insufficient, and improvements are given. This paper provides a basis for dynamic performance analysis and optimization of turning and grinding combined machine tool, and provides a reference for dynamic analysis of less-freedom machine tools.