Study On Cutting Process Of Rare Earth Modified Ultra High Strength Steel With High Pressure Abrasive Water Jet

Abrasive water jet processing technology is essentially different from thermal processing technology.Due to the cooling effect of water,the processed surface will not cause chemical reactions due to high temperature,resulting in the loss of material elements.This makes the technology have strong counterparts and broad application prospects in the field of special materials processing and precision processing.For the research of new material processing technology is necessary,this paper selects a new type of rare earth alloy material as the target material,studies the effect of abrasive water jet process parameters on cutting quality,and preliminary explores the performance of the material in abrasive water jet cutting.This paper mainly studies the process of cutting rare earth metamorphic ultra-high strength steel by post-mixed abrasive water jet and the erosion damage mechanism of cutting section.Firstly,the force of abrasive particles in the fluid is analyzed.The ICFD fluid module of LS-DYNA is used to establish a high-pressure water jet fluid model.The process of mixing and accelerating the abrasive particles with the high-speed water jet in the mixing chamber and the inner and outer flow fields of the sand tube was explored.Combining the abrasive water jet erosion mechanism and the SPH method theory,a post-mixed highpressure abrasive water jet cutting model was constructed using the coupling method of the finite element model,SPH particle model and discrete particle model.The process of cutting the target material by abrasive water jet was numerically simulated.The roughness of the cutting section was obtained by extracting the position information of the node.The influence of cutting parameters on the quality of the section was studied.Due to the unique mechanical properties of the selected target material,a comparative analysis method is used in this paper to explore the abrasive water jet cutting process of this rare earth alloy material and three other metal materials from two macro aspects of cutting performance and erosion damage morphology Performance.From the macroscopic abrasive motion trajectory,the changes of abrasive particle erosion angle and motion speed are mastered.Using the method of coupling SPH particles with the finite element model,the collision model of abrasive impact target was established,and the damage mechanism and surface roughness distribution law of the cutting section were analyzed from the particle level.The results show that in the flow field in the sand tube,the jet realizes the transition from fluid kinetic energy to pressure to kinetic energy at the convergent section of the cone.At the same time,the acceleration process of the abrasive particles also shows a staged change,and the speed eventually reaches about 90% of the fluid speed.After the abrasive particles enter the external flow field of the sand tube,they will continue to do accelerated motion and the acceleration will be greater.In terms of cutting quality,with the increase of jet pressure and abrasive flow,the roughness value of the section decreases nonlinearly,and when the jet pressure exceeds 380 MPa and the abrasive flow exceeds 350 g/min,the effect on the roughness of the section is not significant;When the target distance is 5 mm,the best cutting cross-section quality is obtained;the traverse speed has the most significant effect on the cross-section quality,and the larger traverse speed will quickly deteriorate the crosssection quality.The cutting performance of rare earth metamorphic ultra-high-strength steel is relatively poor.In the same time,the cutting depth and cutting efficiency of No.45 steel can reach about twice.During the erosion damage of the material,there are a large number of high-speed abrasive particles with an impact angle in the upper half of the cut.The microplowing effect of these particles makes the roughness of the section smaller;the lower half of the cut has a part of the low velocity with the impact angle Abrasive particles,the impact deformation of these particles makes the section roughness larger,forming erosion stripes.