Study On Packing Density Of Metal Powder Particles Used In Metal 3D Printing

The Discrete Element Method(DEM)was used to numerically simulate on the packing density of spherical particle with different size distribution,include analyze the effect of sphere stiffness,packing depth,container size on the packing density of the normally distributed spherical particles by the visual programming software PFC5.0.The dynamic characteristics and optimal parameters of the particle packing under different spherical model were obtained,and the spherical particles with normal distribution for particle size were physically experimented on the threedimensional vibration test rig to obtain the density distribution under different vibration conditions.The purpose is to discuss the high-density of metal powder particle packing in vary vibration condition with normal particle size distribution,further extensively study the packing density of metal powder particles,and improve the performance of metal 3D printing molding parts.Firstly,the spherical particle accumulation model was established by using the spherical particle accumulation theory and the actual metal powder particles.Secondly,through the discrete element visual programming software of particle flow,the dynamic analysis of the particle packing density with normal particle size distribution was carried out to accurately characterize the stress,movement and arrangement of particles during the process of particle packing.By changing the experimental parameters of numerical simulation,the influencing factors of particle packing were compared and analyzed.Finally,through the vibration experiments to get different optimization vibration parameters value about the packing density,meanwhile,the numerical simulation results are verified.The research results are as following:(1)By analyzing the porosity change curve of particle packing with mean value of 0.3mm and variable variance,the result show s that with the increase of variance,the porosity tends to decrease firstly and then increase.In contrast to the packing density trend,the maximum value of packing density is 0.795 when the particle model with mean value of 0.3mm and variance of 0.2.(2)As for mono-sized sphere model,when the packing depth is constant,the packing density first decreases with the increase of the sphere stiffness.When K is greater than or equal to 5e9N/m,the packing density increases slowly and tends to be stable.When K is greater than or equal to 9e10N/m,the packing density of the spheres remains 0.63 and does not change.When the packing depth is different,with the increase of spherical particle stiffness,the porosity difference value of vary packing depths gradually shrinks and approaches 0.(3)As for the spherical particles size with normal distribution,the porosity of particle in the packing container generally increases first and then stabilizes.When the stiffness value K is greater than 5e9N/m,the growth trend is faster.When the stiffness value K is more than 1e10N/m,it remains basically stable,Particle Packing density finally tends to 0.346.(4)When the vibration condition is applied to the particle packing,there is an optimal matching parameter between the vibration frequency and amplitude,and for the particle with packing density,the larger the vibration frequency is,the smaller the corresponding matching amplitude parameter is.