Comparative Experimental Investigations On Milling And Mill-grinding Processing Of Aramid Fiber Composites

Aramid fiber composite materials are more and more widely used in military,aerospace and sports equipment due to their excellent mechanical,physical and chemical properties.The structural complexity of components is gradually increasing,and the requirements of cutting processing are becoming stricter.However,the heterogeneity and complexity of the aramid fiber composite material leads to inhomogeneity and anisotropy.The basic principles of metal cutting are no longer applicable,resulting in low cutting quality,serious defects,severe tool wear and other problems.Therefore,it is very important to improve the cutting quality,reveal the cutting mechanism,and study the fracture mode of composite materials.In this paper,two processes of milling and mill-grinding are selected for comparison,in order to obtain the changing principle of cutting force and chip shape during the cutting processing,study the material fracture mode,and analyze the material forming mechanism.The research content of this article mainly includes the following parts(1)An analysis model of the cutting process of aramid fiber composites was established by analyzing the composition of the material and the characteristics of each phase.The functional relationship between fiber strength and strain rate was established through mathematical deriving,the material forming mechanism under different cutting conditions was described,the relationship between macro-process parameters and meso-mechanical behavior was established,and calculation method of internal stress state of materials based on macro-process parameters and real-time cutting force data was proposed.(2)In order to study the mechanical behavior of aramid fiber composite materials in cutting processing,the cutting force signals of two processes were compared and analyzed.The cutting force fluctuation,oscillation,amplitude characteristics and frequency domain characteristics were analyzed to establish the relationship between cutting force signal characteristics and the cutting state.It was proved the existence of single-tooth cutting and multi-tooth cutting in milling,and revealed the mechanism of action about multiple blades and materials in the mill-grinding process.(3)The chip morphology and micro-fracture morphology were summarized.The distribution and change trend of the chip morphology of the two processes in the process parameter window were found.The differences between metal and aramid fiber composite cutting chips were explained.(4)The meso-morphological characteristics of the processed surface of the aramid fiber composite material were predicted through the theoretical calculating and analyzing of the internal stress state of the material,results between calculating and cutting test were compared,and a certain consistency was existence.