Design And Performance Of Large Clearance Magnetic Liquid Sealing For Rotating Shaft Based On Axis-diameter Combined Structure

With China’s coal industry upgrading continuously,mine equipment presents the development trend of being large-scale,high-speed and intelligent.In order to meet the development requirements of mine equipment,its key rotating parts are also developing in the direction of high reliability,long life and low energy consumption.Mine equipment usually works in harsh environment,and reliable sealing is an important guarantee for its normal work.Once water vapor,dust and other pollutants break through the sealing and invade the interior of the rotating parts,the bearing lubrication will fail,resulting in increased rotating resistance and even stuck failure.Therefore,in view of the working conditions and environmental characteristics of mine equipment,this thesis takes the belt conveyor idlers which are more common in mine equipment as an example,the research on the high reliability sealing method of rotating parts is of great practical significance to improving the reliability of the sealing device.This thesis aims to improve the service life and sealing reliability of the sealing device of the key rotating component of mine equipment.Based on the principle of magnetic liquid sealing,this paper breaks through the traditional axial single type magnetic liquid sealing structure,and designs a large clearance magnetic liquid sealing structure of axis-diameter combined rotating shaft.The sealing performance of the sealing structure is studied by theoretical analysis,simulation and experimental verification.Firstly,the magnetic fluid with good stability,high saturation magnetization,good temperature resistance and suitable for large clearance magnetic fluid sealing structure was prepared.The influence of temperature,material ratio,p H value and other factors on the properties of magnetic particles were analyzed.VSM,XRD,SEM and other methods were used to characterize and analyze the magnetic particles.The results show that the magnetic liquid has good stability and magnetism when the concentration of magnetic particles is 5%.Secondly,the structural scheme of the axis-diameter combined large clearance magnetic fluid sealing and its main sealing components are designed.The dimensional parameters of the sealing components are optimized by ANSYS finite element simulation software.and the magnetic field line distribution,magnetic induction intensity distribution and the magnetic induction intensity in the sealing clearance were simulated and analyzed after optimization,which verified the rationality of the design of the sealing structure.According to the pressure resistance theory,the pressure resistance capacity of the sealing structure is 0.121 MPa,which is 41.03% higher than that of the single axial sealing structure.Finally,the sealing performance test of the sealing structure under simulated mine environment was carried out by using the roller rotating resistance test bench.The results show that the rotating resistance of the axis-diameter combined large clearance magnetic liquid sealing structure decreases by 7.6% on average and 18.7% on maximum compared with the traditional labyrinth seal structure in the constant load test.In the constant speed test,the rotating resistance of the axis-diameter combined large clearance magnetic liquid sealing structure decreases by 34.3% on average and 50.2% on maximum than that of the traditional labyrinth seal structure.In the long time running test,the mean value of rotating resistance of the axis-diameter combined large clearance magnetic liquid sealing structure is reduced by 16.2% compared with the traditional labyrinth sealing structure.and the magnetic liquid prepared in this paper shows better stability and heat resistance than the coal-oil magnetic liquid sealing structure in the three tests.In the test under vibration environment,the axis-diameter combined large clearance magnetic liquid sealing structure has more reliable sealing performance than the single axial magnetic liquid sealing structure with smaller clearance.The research results are of great significance for broadening the application field of nano-magnetic liquid,making up for the deficiency of traditional sealing device structure,reducing energy loss during equipment operation,reducing transportation cost and improving work efficiency.There are 69 figures,16 tables and 110 references in this thesis.