The Experimental Study Of Surface Integrity On Narrow Deep Groove With Creep Feed Grinding Of AISI 1045 Steel

As a special structure of important parts such as pump body and engine,the geometric accuracy and processing surface quality of narrow deep groove directly influence the reliability and service life of components,which affects the stable operation of the whole structure.The traditional machining process combining milling and grinding has low production efficiency and insufficient processing precision,which cannot fulfill the requirements of modern industry.In this paper,CBN is used as the abrasive to make single-layer electroplated CBN grinding wheel by electroplating process.The experiment of high-speed creep feed processing of AISI 1045 steel was carried out,and the surface morphology,surface roughness,the hardness of groove bottom and subsurface structure of narrow deep groove were observed.The friction and wear properties of the matrix and groove side were tested respectively,and the relationship between the surface integrity of narrow deep groove and the process parameters was analyzed.At the same time,the finite element model of grinding by single abrasive was established to simulate the grinding force and temperature history under different grinding parameters during the grinding process.The main research work and results of this paper are as follows:(1)The grinding theoretical model of narrow deep groove was established.The length of contact arc between the grinding wheel and workpiece in the grinding process was derived,and the material removal mechanism of the top and side edge areas of the grinding wheel was analyzed.The formula for calculating the grinding force of a single abrasive grain was deduced,and several typical formulas for the creep feed grinding force and the maximum thickness of the undeformed chip are summarized.(2)The finite element model of CBN single abrasive grinding AISI 1045steel was established.The grinding speed,the grinding depth and the rake angle are set to four levels respectively,and the simulation data of the grinding force and temperature under different grinding parameters are obtained.The results show that under high-speed grinding conditions,increasing the grinding speed can reduce the grinding force effectively,but the grinding temperature will increase accordingly.As the grinding depth increases,the thickness of chip increases,and the anti-plastic deformation of material is enhanced,therefore the grinding force and the grinding temperature both increase.With the increase of negative rake angle of abrasive grains,the shearing action of the abrasive front blade against the material is weakened,thereby the material is not easily separated from the workpiece and the thickness of chip is increased.The grinding force and temperature also increase.(3)The effects of grinding parameters on the surface profile,surface roughness,the hardness of groove bottom and subsurface structure of the narrow deep grooves were studied.The surface characteristics of narrow deep grooves under different grinding conditions were tested.The results show that the surface roughness of the narrow deep groove obtained under the condition of v_s=70m/s,v_w=1.5mm/min and a_p=10mm is the lowest.Surface scratches are shallow and sparsely distributed,and the surface quality is better.When the feed speed of the workpiece and the depth of grooves are lager,the size of surface scratch is large and disorderly distributed,so surface quality is poor.Compared with the hardness of the matrix,hardening occurs at different positions along the groove bottom in the grinding direction,and the hardness is highest in the middle position of the workpiece.Under the condition of v_s=50m/s,v_w=3mm/min,a_p=10mm,the hardness of the bottom area in the middle area can reach 387HV;When the machining condition is v_s=50m/s,v_w=1.5mm/min,a_p=15mm,the hardness of of the workpiece in the middle area is 361 HV,which is about twice than the hardness of the matrix.The observation results show that the subsurface structure of the narrow deep groove is similar to the matrix structure,and no tissue transformation occurs.The subsurface layer of the groove bottom has a distinct stratification phenomenon,and the structure near the bottom of the groove is dense with the generation of microcracks.The lower area is the transition layer,the matrix and the hardened layer are mixed and distributed,away from the bottom of the groove is a typical matrix structure.(4)Perform friction and wear experiments on the sides of narrow and deep grooves.The surface friction coefficient,wear scar width,wear scar depth and material removal volume of the workpiece under different process conditions were compared and analyzed.The research shows that the initial roughness of the surface has a direct influence on the friction coefficient,and the smaller surface roughness value can obtain a larger friction coefficient,indicating that the wear resistance of the material is improved.The larger workpiece feed speed and the narrow depth of the groove make the surface roughness value higher,and the workpiece surface material removal volume is larger,and the wear resistance is reduced.