Research On The Supporting And Lubrication Properties Of Magnetic Fluids Bearing

The magnetic fluid is a relatively stable colloidal liquid formed by uniformly dispersing nanometer-scale magnetic particles in a base carrier liquid.As a new functional material that is distinct from traditional liquid lubricants,magnetic fluids accumulate and magnetize under the action of an external magnetic field,which is equivalent to the work of the magnetic field,and the energy is stored in the magnetic fluid in the form of magnetostatic force.Starting from the actual demand of lubrication,the magnetostatic force inside the liquid can provide support for the friction pair,which can better achieve the effect of lubrication and friction reduction.Because of its good sealing performance,magnetic fluids are widely used in the field of sealing and lubrication.Combined with the excellent sealing properties of magnetic fluid,good static support force and lubrication characteristics,this study proposes a liquid/gas hybrid support and lubrication bearing structure based on magnetic fluid seal.By designing suitable permanent magnets,the magnetic fluid is rubbed.The secondary surface forms a closed liquid structure.In the magnetic fluid under the action of a magnetic field,in addition to self-magnetization and cohesion to generate liquid supporting force,the gas sealed by the magnetic fluid in its liquid structure will further enhance the supporting ability.The magnetic fluid-sealed liquid/gas support structure transforms the traditional binary solid/liquid lubrication interface into a solid/liquid/gas ternary interface,and the resulting mixed support force is independent of the sliding speed between the pair of carbon pairs,even if the air cavity bearing can also carry the other surface and achieve low friction at rest or at low speed.The research verified the above ideas through experiments,and obtained the key factors affecting the support and lubrication effects,which laid a foundation for the realization of liquid/gas hybrid support and lubrication design based on magnetic fluid seals.This study has application value for solving the "cold welding" phenomenon that often occurs in precision sliding mechanisms and the "crawling" phenomenon existing in low speed state.The study mainly obtained the following conclusions:(1)Under the action of external magnetic field,in addition to the supporting ability of the magnetic fluid itself,the air cavity generated by the magnetic fluid seal can withstand a certain load.The supporting force of the fluid/gas-filled fluid/gas hybrid bearing is the same condition.More than twice the static magnetic force of the magnetic fluid.(2)Theoretical analysis shows that the sealing ability of the magnetic fluid determines the supporting ability of the ferrofluid pocket bearing,which has also been verified by experiments.The static support force experiment shows that the support capacity of the magnetic fluid sealed air cavity bearing varies with the amount of magnetic fluid and the volume of the magnetic fluid sealed air cavity.The enhancement of the magnetic field on the surface of the magnetic ring changes the viscosity of the magnetic fluid,and the sealing ability and supporting ability of the magnetic fluid are effectively improved.(3)The experimental results of static support force were verified by tribological experiments.The participation of the sealed air chamber makes the lubrication state between the contact surfaces change from the traditional liquid lubrication to the liquid and gas mixed lubrication,which improves the lubrication effect of the magnetic fluid.The higher the surface magnetic field strength of the permanent magnet,the stronger the ability of the magnetic fluid to seal the air inside the cavity,which improves the bearing support force and also plays a good lubrication and drag reduction effect.(4)The multi-ring array arrangement has obvious advantages over the single magnetic ring in terms of static support force and lubrication.The magnetic ring NS-level staggered adjacent arrangement not only improves the magnetic fluids sealing performance,but also obtains more air chambers.The sealing dam formed by the multi-ring array has synergistic effects,which greatly expands the application of magnetic fluid in the fields of sealing,support and lubrication.