Technology Of Magnetic Rolling On The Inner Surface Of Long Pipes

Research shows that the surface quality mainly affects the wear resistance,corrosion resistance,contact stiffness,fatigue strength and coordination properties of parts.There is much oxide skin on the inner surface of stainless steel pipes,which widely used in industrial areas,due to the high temperature solution treatment for the stainless steel pipe production,a layer of compact oxide skin formed on the inner surface of stainless steel pipes,which results the decrease of roughness and corrosion resistance for the pipes.Thus,the stainless steel pipe can not meet the occasion which requires the high quality of the inner surface,seriously affected the use of stainless steel pipe.To remove the oxide skin,the inner surface of stainless steel pipe has been grinded by magnetic grinding,the preliminary study found that the oxide skin was adequately removed by magnetic grinding,but the surface hardness was low and there were a lot of clear scratches and waviness on the inner surface of stainless steel pipe after magnetic grinding,therefore the magnetic rolling technology has been put forward to further improve the quality of the inner surface of stainless steel pipe and increase the use value of the pipe.Magnetic rolling technology,which applies magnetic force into rolling processing,is an organic combination of magnetic field control technology and rolling processing technology.In this paper,studies mainly from the aspect of mechanism of magnetic rolling,the influencing factors of processing effect,the process of designing magnetic rolling system,the magnetic rolling test:? Implemented an analysis of the mechanism of magnetic rolling processing.Based on the influencing factors of the effect of traditional rolling processing,and combined with the characteristics of the magnetic rolling processing,the influencing factors of the effect of magnetic rolling are deeply analyzed.? Based on the mechanism of magnetic rolling,the influencing factors of processing effect and the characteristics of permanent magnet,and combined with magnetic circuit designing and structure designing of magnetic system,the overall scheme of magnetic rolling test platform is determined;Aiming at the magnetic rolling test platform and basing on the principle of high magnetic circuit matching and favorable rolling performance,the structure for the rolling tool is determined.Based on Ansoft Maxwell software,the finite element simulation of the whole magnetic rolling system is carried out.The simulation results showed that the magnetic field distribution and magnetic flux density distribution of magnetic rolling system met the requirements of magnetic circuit design.The magnetic rolling system had favorable force characteristics,meeting the rolling processing requirements,could achieve the rolling processing on the inner surface of workpiece.? Built the magnetic rolling test platform,researched and developed a rolling tool,the magnetic rolling test with the test object of long stainless steel pipe(0Cr18Ni9)provided by users is conducted,the test results showed that: the rolling tool rotated with the rotary magnetic field generator synchronously,changing the input frequency through the inverter,the rolling tool could get different speed to meet the different processing requirements,which verified the feasibility of magnetic rolling processing.? The magnetic rolling process parameters are studied in this paper,the effects of rotating speed of rolling tool,axial feeding speed and rolling stroke on the surface roughness and surface hardness of the workpiece are investigated via magnetic rolling tests,the optimum process parameters of 0Cr18Ni9 stainless steel pipe have been obtained,laid the foundation for the subsequent research on magnetic rolling technology.? Conducting the magnetic rolling test with the best optimum process parameters(input frequency of the inverter is 20 Hz,axial feeding speed is 0.4m / min,rolling stroke is 8),the results show the inner surface roughness Ra of stainless steel pipe is reduced from 1.860?m to 0.665?m,reaching the fine machining level,the surface hardness is increased from 82 HRB to 97 HRB,the quality of the inner surface of stainless steel pipe has been greatly improved,the useful value of stainless steel pipe has been greatly improved.The technology of magnetic rolling provides an effective finishing and strengthening method for the inner surface of long pipes.