Vibration Analysis And Optimal Design For Boring Bar Of Deep Hole Pulling Boring Machine

Pulling boring machine is one of the most important equipment to manufacture deep hole parts. The quality of work piece is depended on machining accuracy of tool, but the special machining environment restrains boring bar's size and shape which needs small diameter and long extended length, that makes boring bar's rigidity weak, then it is easy to vibration in the processing, and affect machining quality seriously, so how to reduce the vibration becomes a critical issue needed to resolve.The object of study in this paper is the boring bar whose draw ratio is 50. In order to study on the cutting process of boring bar, it is need to create a dynamic equation for boring bar system. On the basis of it, the dynamic equation of boring bar system is solved accurately; its dynamics performance is analyzed and its structure optimized by use of the finite element analysis software ANSYS. Including:Firstly, presents theoretical analysis of boring bar vibrating system, creates the simplified model for pulling boring bar and on the light of these, the equations of motion for various vibration presenting in the boring process are created.Secondly, some factors are researched such as cutting angles and forces as well as elasticity coefficients of elastic supports, all of these affect the boring bar vibration system. This paper builds the mathematical model for the cutting angles, makes static analysis for boring head and presents the coupled equations of motion for system to determine the conditions which cause self-excited vibration and to define the functional relation between conditions and elasticity coefficients of elastic supports.Thirdly, static analysis is made to determine places where stress concentrations appeared in boring bar whose intensity and stiffness are checked. By dynamic characteristics, the first ten step natural frequencies and model patterns are obtained by modal analysis. Boring bar's resonant frequencies presented under the action of a external excitation are gotten by harmonic response analysis, and transient dynamic responses are obtained for boring bar's starting and ending cutting.Finally, the boring bar's parameterization model is build by the ANSYS parametric design language, and the section diameter of hollow boring bar is regarded as design variable to optimize for getting the optimal solution.