Simulation And Experimental Study Of Soft Abrasive Flow Conical Micropore Finishing

As a finishing technology,abrasive flow technology has been widely used in industrial production,mainly to complete the cavity of the parts of the deburring,entry and other finishing.With the development of high and new technology toward miniaturization,small cone holes are widely used in some components to meet certain functional requirements,and have higher requirements for the surface quality of the channels.The soft abrasive has a certain micro cutting effect on the micro channel,finishing for the fine machining,chamfering and deburring of the microporous.And the removal of the microporous surface material decreases gradually from the entrance to the exit.In the process of machining cone holes with soft abrasives,the results of micro holes forming can be changed by changing the processing parameters of soft abrasive.But the actual change of the micro pores after soft abrasive machining is unknown.In this paper,the research of soft abrasive flow technology at home and abroad and the flow characteristics of two-phase soft abrasive flow machining micro cone is analyzed.While the soft abrasive machining micro hole test,equipment configuration,test results,test of micro hole boring numerical simulation experiments has been researched.The main research contents,methods and conclusions are as follows:(1)The flow characteristics of soft solid-liquid abrasive flow in a micro channel and its motion characteristics of the abrasive particles are investigated,and the material removal method of abrasive flow machining microporous is clarified.The kinetic characteristics of the abrasive grains and the kinematic characteristics of the liquid phase are analyzed in detail from the solid and liquid phases.The force equation of the single abrasive grain and the velocity distribution of the soft liquid phase are clarified.The formula and method of Preston coefficient of soft solid-liquid abrasive flow were determined by experiment.The k_p of Preston equation based on soft abrasive flow was modified,and the k_p based on the Preston equation parameters of the soft abrasive with different mass fraction flow are measured and calculated.(2)The various equipment used in the conical micro-pore test of soft abrasive flow and the structure,material of test-piece and tungsten steel drill used in the specimen are introduced.The medium used in soft abrasive force,abrasive particle and preparation method are also introduced.The viscosity of different grades of mass is determined by viscometer,and the mass fraction of soft abrasive is directly proportional to its viscosity.This paper also introduces the abrasive extrusion equipment for the processing of conical micro-pore with soft abrasive flow.At the same time,the equipment and method for cleaning and measuring relevant parameters after the completion of micro abrasive machining are also introduced.(3)The simulation analysis of the micro-pore forming fof soft abrasive was carried out.The distribution of the pressure and velocity of the abrasive grains in the soft abrasive stream at the microporous wall was obtained under the action of a certain cylinder pressure.The results show that the pressure of the abrasive particles at the micro-pore wall decreases gradually from the inlet to the outlet under at a certain pressure,and the velocity of the abrasive particles at the micro wall varies little from the inlet to the outlet.The pressure distribution of the abrasive grains on the micro-pore wall and the material removal on the microporous surface were analyzed under different particle sizes and different abrasive mass fractions.The simulation based on Preston equation,The amount of material removal at the different locations of the micro-pore along the channels was calculated in the state where the cylinder pressure was 3 MPa,the mass fraction was 30%,and the abrasive grain size was 2000 mesh,and the influencing factors of micro-shaped taper forming are analyzed.Finally the taper angle formed under certain processing conditions is obtained.Meanwhile A three-dimensional reconstruction technique of micro-pore for soft abrasive processing is also proposed,so that the amount of material removed by the Preston equation can be calculated.(4)The effects of the cylinder pressure,the mass fraction of the abrasive flow and the particle size on the taper machining of the micro hole were analyzed by experiments.The results show that the micro-pore taper increases with the increase of the cylinder pressure when the processing time is constant.With the increase of mass fraction of soft abrasive,the conical micro-pore taper becomes more and more large,and increasing the mass fraction can improve the material removal rate of the soft abrasive on the microporous wall.With the increase of abrasive particle diameter in soft abrasive,the conical micro-pore taper becomes more and more larger,and material removal rate of the micro-pore wall will show a downward trend when the size of the abrasive affects the smoothness of the abrasive through the micro=pore.(5)The comparison of the test and simulation under different processing parameters was carried out,the contrast error is less than 20%,and most of which errors are about 10%.The theoretical simulation is in good agreement with the actual test.The degree of influence on the size of the micro-pore angle is from large to small are:,cylinder pressure,mass fraction,abrasive grain size.