| Powder metallurgy is a near net forming process that outperforms traditional casting processes in terms of energy conservation,material efficiency,product accuracy,and mass production due to its characteristics of minimal and no cutting.However,under current technological conditions,parts produced by powder metallurgy cannot be directly used,so a small amount of mechanical processing is required to meet production and usage requirements.As a kind of difficult to machine material,due to the high hardness of sintered P/M parts,problems such as serious tool wear,chip accretion,and many defects on the machined surface are easy to occur during machining.How to reduce the loss of powder metallurgy processing,improve its production efficiency,solve the problems of enterprise production and processing,and promote its wider application is currently a problem faced by the industry.This article focuses on the cutting technology of powder metallurgy green materials,using finite element simulation technology as the main research method,combined with experimental methods,to study the cutting process of powder metallurgy green materials,develop the processing technology of powder metallurgy green materials,optimize cutting parameters,and other work.The main research content includes:(1)Choose to use ABAQUS software to establish a two-dimensional orthogonal cutting simulation model for powder metallurgy raw materials.Construct a constitutive model of powder metallurgy green materials and simulate the pore structure in the matrix.Obtain the relevant material properties of powder metallurgy green billets through preliminary experiments and literature review,and modify the relevant parameters of the model.(2)Perform finite element simulation on the green model,and verify the accuracy of the powder metallurgy green finite element model based on the validation experimental results and the previous summary of the green material removal model.Based on simulation results and experimental verification,it is found that the size of the chip is mainly related to the cutting thickness.When the cutting thickness is small,the chip morphology is mainly a mixture of small particles and powder,and the size of the pits on the processed surface is relatively small;As the cutting thickness increases,the number of small particles in the chip increases significantly,and the number of pits on the machined surface also increases accordingly.In addition,the simulation results indicate that there are defects on the cutting surface,such as holes left by material fragmentation and cutting,and burrs formed by matrix tearing,resulting in many randomly distributed and varying size pits on the machined surface.(3)Through the analysis of simulation experimental results on cutting force,it was found that as the cutting speed increases,the change in cutting force is not significant,while as the cutting depth increases,the cutting force increases linearly.The single factor analysis of variance method was used to analyze the effects of cutting speed and cutting depth on cutting force,and it was found that the impact of cutting speed on cutting force was not significant,while the impact of cutting depth on cutting force was very significant.Based on the analysis results,the cutting speed and depth were optimized and selected,and the optimal cutting parameters were obtained: cutting speed of 100 m/min,cutting depth of 0.2 mm,and cutting force of 2.65 k N. |
