Study On The Process Of Sintered NdFeB With Magnetic Field Assisted EDM

Sintered Nd Fe B,as one of the common permanent magnet materials,is a tetragonal crystal composed of neodymium,iron,and boron,which has a high magnetic energy product.The material has the advantages of low production cost,small size,high energy density,etc.;but its shortcomings are also obvious,such as brittleness,difficult processing,and poor thermal stability.Sintered Nd Fe B is a typical difficult-to-process material,and it is difficult to process with traditional processing methods.Scholars at home and abroad have little research on the processing method of sintered Nd Fe B and the magnetic properties after processing.According to the characteristics of sintered Nd Fe B materials,this research uses the non-contact processing method of EDM,and uses the magnetic field as an auxiliary means to realize high efficiency,high quality and high performance processing of sintered Nd Fe B materials.This study analyzes the machining mechanism of transverse magnetic field and longitudinal magnetic field assisted EDM,and derives the trajectory of the charged particles in the discharge channel under the combined action of electric field force and magnetic field force.Studies have found that the action of the transverse magnetic field will shift the movement trajectory of the charged particles,while the action of the longitudinal magnetic field can make the movement of the charged particles spiral.The magnetic field increases the discharge energy by increasing the chance of particle collisions in the discharge channel.On the basis of theory,a test platform was built to form a transverse magnetic field and a longitudinal magnetic field respectively.By changing the magnetic induction intensity,peak current,pulse width,pulse interval and other parameters of the magnetic field,the effects of processing parameters on processing efficiency were experimentally studied.Analyze the machining efficiency change law of transverse magnetic field and longitudinal magnetic field-assisted EDM,and compare it with non-magnetic field EDM.The test results show that both the transverse magnetic field and the longitudinal magnetic field will improve the processing efficiency,and the processing efficiency of the transverse magnetic field is higher than that of the longitudinal magnetic field and the non-magnetic field EDM.As a hot working method,EDM will affect the surface magnetic flux density of sintered Nd Fe B,and the effect has regularity.Through experimental research methods,the influence of processing parameters such as transverse magnetic field and longitudinal magnetic field,peak current,pulse width,pulse interval,etc.,on the surface flux density of sintered Nd Fe B EDM is studied.The study found that the surface magnetic flux density is greatly affected by heat.The greater the discharge energy in EDM,the more obvious the effect on the surface magnetic flux density of Nd Fe B.The transverse magnetic field and the longitudinal magnetic field can slow down the decrease of the magnetic flux density of the machined surface.The surface magnetic flux density of the longitudinal magnetic field EDM is higher than that of the transverse magnetic field and the non-magnetic field EDM.Surface quality is an important indicator for the research of EDM effects.Research and compare the surface roughness,surface morphology,cross-section,etc.of transverse magnetic field,longitudinal magnetic field and magnetic field-free EDM.The study found that the surface roughness of transverse magnetic field EDM is lower than that of longitudinal magnetic field and non-magnetic field EDM,and the thickness of the surface recast layer is thinner.There are more surface microcracks and pores when there is no magnetic field.The analysis found that the transverse magnetic field and the longitudinal magnetic field have the effect of reducing surface micro-cracks and pores.