Machining Method Based On Compound Spiral Abrasive Flow And Spiral Abrasive Flow Field Modeling

The key aluminum alloy workpieces of aeronautics and astronautics are with high precision and surface quality requirements,and the traditional machining methods are hard to resolve the above matters.This paper proposes a novel compound spiral abrasive flow machining method for the above questions.The proposed method makes the spiral restrictive tooling and axial feeding motion effect on the abrasive flow field,increase the abrasive flow velocity and turbulent intensity,and decrease the initial pressure requirements.The relative tasks are described as follows.(1)Based on the Euler multi-phase flow model,in combination with the circumfluence component,the momentum equations of particle phase and fluid phase oriented to compound spiral flow field are obtained.According to the RNG turbulent flow model,a compound spiral flow field dynamic model that can describe the physical space with large curvature is set up.Referring to the above model,the dynamical pressure and velocity of near-wall region are solved,and the abrasive flow distribution characteristics and variation regulars in the machining process are acquired.(2)According to the pressure and velocity obtained from the flow field computation,a particle-wall collision model for compound spiral flow is built up.Combining the particle collision dynamic theory,the machining mechanism of compound spiral abrasive flow is analyzed.The numerical results prove that the material removal is not apparent in the early stage of collision process;with the increment of the collision times,the material removal quantities are increase gradually;the function of the particle collision frequency and the amounts of material removal is obtained.The thickness of the damage layer and the damage area increases with the particle incident angle increases,but the amounts of material removal are increased first and then decreased,and reaches the peak at 30o.The function of the incident angle and the thickness of the damage layer,the damage area or the amounts of material removal are obtained by curve fitting,respectively.(3)By using the high speed photography and PIV technologies,an observation platform is developed.The particle-wall collision process and particle trajectory are obtained,and the friction and cutting effects are observed.The PIV observation results show that the compound spiral structure can improve the abrasive flow speed and Saffman force,increase the probability the particle-wall interactions,and enhance the machining efficiency.Moreover,the method can increase the vortices of the flow field,and the surface quality is guaranteed.(4)Taking the surface-oxidation aluminum alloy frictionless cylinder as an instance,a machining experimental platform is established,and the buffer apparatus influence to the machining process is analyzed.The machining experiments results prove that the proposed method can provide higher flow velocity and centrifugal force,increase the collision probability of particle and workpiece,and the machining efficiency and surface quality are improved.