Design And Research Of Special Equipment For Deep Hole Internal Cogging Of CFRP Parts

CFRP have a wide application prospect in military industries and aerospace due to their high specific strength,high specific modulus etc.Its characteristics such as laminated structure and anisotropy leads to extremely uneven cutting force during processing.The structure and size of the boring bar are restricted because of the deep-hole structure of CFRP.This produces the low stiffness of the bar,which can easily lead to stress deformation and vibration in the cutting.A large quantity of inner tooth grooves are distributed on the surface of the deep-hole,which requires repeated radial feeding and retracting.As a result,difficulties are considerably increased on the processing.This article has made a study on the design of specialized technological equipment for CFRP part deep-hole alveolar machining.Firstly,this article researched the machining mechanism of CFRP.According to the structure features of CFRP part deep-hole alveolar,the processing scheme of deep-hole alveolar was analysed.The small chisel-edge molding blade was designed for it and a reasonable processing technological route was formulated.Secondly,considering the processing difficulties of the alveolars,a specialized boring bar was designed.The mechanical model were established,which turned out that the static deformation and steady-state response of the specialized boring bar were reduced obviously.The finite element simulation has been used to analyse the characteristics of various boring bars,drawing a conclusion that the three-edge specialized boring bar achieved the best statics performance.Compared with the ordinary bar,its total deformation and radial deformation of the blade bit was reduced by 29.9%and 39.1%.With similar inherent frequency of the first two stages,the amplitude of the specialized bar has been decreased greatly to ensure an excellent dynamic property.Consequently,The overall layout proposal for the specialized machine tool was formulated in accordance with the processing requirement of the alveolars,each component part of the machine tool was designed and the virtual assembly was completed.The dynamical model of the linear feed system was established and the dynamic properties of various feed systems were analyzed by finite element simulative analysis method.Results have shown that the O-shaped feed system with a distance of 250mm between sliding blocks achieved an optimal dynamic characteristics.And a statics checking calculation was also carried out for this system.