| Porous material can supply millions of micro-hole regarded as countless restrictor,therefore,porous aerostatic bearings have higher load capacity and static stiffness and better stability than traditional orifice restrictor and slot restrictor aerostatic bearings.It is needed for porous material to have good air permeability and high strength and stiffness if it acts as the restrictor of porous aerostatic bearings requires ensuring that the porous material will not be deformed or destroyed under high pressure.At present,the existing graphite porous restrictor and sintered metal powder porous restrictor can only work under low pressure and cannot withstand high pressure.The wire mesh itself has a pore structure,and the continuous non-breakage of the wire that forms the network makes the wire mesh have high mechanical properties.In order to obtain a metal porous material with metal wire mesh as raw material,and simple preparation process,high strength and stiffness,and that can be directly used in shaping and processing,this paper proposed a new method for processing sintered metal porous plates,and investigated the effects of parameters of preparation technology on pore structure,structural characterization,mechanical properties,and molding properties of the materials.Finally,the static bearing capacity of air thrust bearing which use the porous plate as restrictor was studied.In this study,a set of stainless steel wire mesh and powder preformed green body manufacturing devices were designed,which included a powder spreading platform,a powder rolling equipment and mesh,and powder winding device.The device has high automation degree,high efficiency,simple structure and convenient use,and is convenient for automation and large-scale production of the green bodies.This paper proposed a process for preparing a new sintered stainless steel porous plate by pressing and rolling,and finally sintering the composite green body with the composite green body of stainless steel wire mesh and a stainless steel powder as raw materials.The sintered stainless steel porous plates with porosities from 10% to 40% and thickness from 0.5 mm to 4.5 mm were prepared by the processing,including the sintered multi-layer stainless steel mesh porous plates that contain no powder,and the sintered stainless steel mesh and powder porous plates.The parameters of porosity pore and skeletal structure,and pore diameter of porous materials determine material functional applications.In this paper,the porosity and skeleton structure of sintered stainless steel porous plates were studied by macroscopic measurement and microscopic observation.The surface pore shape of sintered stainless steel mesh porous plates was regular square.As the surface wires being rolled into flat shape,the internal pores were rectangular in different sizes due to the random distribution of wire,where the pores were connected to each other.The surface pore shape of sintered stainless steel wire mesh and powder porous plate showed irregularity and different shape due to powder embedded into the mesh.The internal pores had body-centered cubic and face-centered cubic shape.The effect of preparation technology parameters on the porosity of sintered stainless steel porous plates was studied.The larger the rolling amount during rolling,the lower the porosity of the material was.The porosity of the material decreases with an increase of sintering temperature.The data comparison showed that the choice of rolling amount had the greatest significant effect on the porosity of the porous plate,and the effect of sintering temperature on the porosity was relatively weak.The parameters of pore diameters of the sintered stainless steel porous plate were studied through the bubble experiment.The pore diameter of multi-microporous stainless steel plate decreases with the decrease of raw material wire diameter and the increase of sintering temperature.The average size of sintered mesh porous stainless steel plates ranges from 4.16 ?m to 5.51 ?m;most porouss are less than 10 ?m,and the size is uniformly distributed.The average diameter of sintered stainless steel mesh and powder composite porous plate is about 20 ?m,the minimum and maximum diameters are 2.3 ?m and 86.3 ?m,respectively.The gas permeability of sintered stainless steel porous plates was studied through gas permeation.The higher the porosity,the better the permeability is.The wire diameter of the raw material also had an effect on the gas permeability,but is not as significant as the the porosity.The sintered stainless steel mesh and powder porous plate have the best gas permeability.The mechanical performance of the material is an important factor to evaluate its performance.The tensile mechanical behavior of sintered stainless steel porous plate was studied through uniaxial tensile test in this article.The effects of parameters such as sintering temperature,wire diameter and porosity of raw material on tensile performance were studied.The tensile strength of multi-microporous stainless steel increases with the increase of sintering temperature and raw material diameter,and the decrease of porosity.Among them,the raw materials with 60 mesh screen,sintering temperature of 1330 ?,porosity of 15% of the stainless steel porous plate had tensile strength of 380 MPa and the density is 70% of stainless steel materials.The impact mechanical behavior of sintered stainless steel porous plates was studied through impact mechanics experiments.The test data show that the impact toughness of multi-microporous stainless steel plate changes with sintering temperature,raw material diameter and porosity.The changing rule is similar to the tensile test.Compared with the sintered stainless steel powder and fiber porous materials,the sinstered stainless steel wire mesh porous plate shows that the tensile strength and impact toughness are greatly improved.The stamping forming performance of the sintered stainless steel mesh porous plate were studied through the bulging test and the tube drawing experiment.The experiments showed that the blank material with a porosity of 15%,a body diameter of 180 mm and a thickness of 1.5 mm,didn't break at a bulging height of 30 mm under a die with a diameter of 110 mm,indicating that the sintered stainless steel mesh porous plate has good plasticity.Single side porous aerostatic bearing with air cavity was designed and prepared with sintered stainless steel mesh porous plate as restrictor,and the static bearing performances of the bearing were studied experimentally.The bearing capacity and static stiffness of a single-side porous aerostatic bearing increased with the increase of the external air supply pressure and the throttle surface.When the area of the restrictor surface was same,both the bearing capacity and static stiffness of partial porous aerostatic bearing increased,so the structural design of the porous restrictor has an important positive effect on improving the static bearing performance of the bearing.Compared with the static bearing performance data of other types of porous aerostatic thrust bearing,the multi-microporous stainless steel plate as a porous retrictor bearing has a higher bearing capacity.The maximum bearing capacity of restrictor with a diameter of 30 mm for the bearing is 5108 N.Based on the theory of fluid mechanics,the mathematical model of the static performance of porous gas hydrostatic bearing is established.By using the computational fluid dynamics software FLUENT,the static performance of the porous gas hydrostatic bearing was simulated and compared with the experimental results,verifying the correctness of the numerical simulation.Finally,the pneumatic thrust bearing made of multi-microporous stainless steel plate is used for vibration reduction test of high-speed motorized spindle.The test results show that the pneumatic bearing has a good inhibitory effect on vibration of high-speed motorized spindle,which is guiding significance for the application of multi-microporous stainless steel plate in the pneumatic bearing. |
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