Study On Mechanism Of Micro-textured Interface Lubrication And Friction Reduction Of Cutting Shrubs Gear Meshing And Anti-scuffing Load-bearing Performance

As the core system of cutting shrubs device,the lubrication bearing characteristics of gear transmission system become the key to determine the overall performance of cutting shrubs device.Taking into account the alternating loads and shrub growth environment requirements of the current forestry cutting shrubs transmission system,in the process of gear meshing,it is an inevitable trend to encounter failure cases such as contact friction thermal behavior and interface thermoelastic scuffing wear,thus affecting the overall performance of the gear transmission system and fatigue life,and seriously lead to the failure of the cutting shrubs device function.How to achieve the lubrication and friction reduction of the gear mesh interface,and then improve the interface lubrication performance of the anti-scuffing loadbearing performance has become a hot research topic.In this dissertation,we aim to introduce a micro-textured interface to the meshing tooth surface in the cutting shrubs device transmission system,and combine the actual operating characteristics of the cutting shrubs device,based on the mechanism of thermo-elasto hydrodynamic lubrication(Thermo-Elasto Hydrodynamic Lubrication,TEHL),gear modification theory and surface micro-textured technology,the presence of suitable micro-textured can produce the coupling effect of "secondary enrichment lubrication" and " micro-hydrodynamic pressure bearing ",improve the lubrication enrichment performance,reduce the risk of solid-solid interface wear contact of the gear pair in the meshing state,and improve the cutting shrubs gear system(Cutting Shrubs Gear System,CSGS)load-bearing capacity,the study of lubrication and friction reduction mechanism and anti-scuffing load-bearing performance of micro-textured interface of cutting shrubs gears was carried out.(1)Based on the actual operating characteristics of the cutting shrubs device in the forest area,the relevant parameters(such as torque and speed)of the gear transmission system operating under complex working conditions are determined,and the associated variables applied to the gear meshing interface are obtained.Taking into account the theory of thermoelasto hydrodynamic lubrication,derive the general form of the Reynolds equation,analyze the mathematical calculation model of the alternate meshing process of the cutting shrubs gear,combine the Hertz contact complete numerical algorithm and the tooth surface interface clearance model,determine the contact line of the meshing tooth surface instantaneous load,and propose the Reynolds equation of the meshing interface contact line load and its dimensionless and numerical calculation method,which provide pre-research conditions for CSGS meshing impact analysis and micro-textured interface lubrication and load-carrying performance research.(2)The research on tooth surface modification considering the meshing impact of cutting shrubs gears is carried out,the mechanism of rolling-slip line contact meshing impact is revealed,the calculation model of gear meshing impact including its velocity is established,and the influence of the tooth surface modification optimization on the impact load distribution is analyzed.Considering the no-load motion error,load distribution coefficient and maximum impact force synthesis at the actual meshing point D along the normal action line of the tooth profile,the influence of the meshing impact load on the contact path of the gear pair and the meshing transmission error is explored.The results show that the meshing impact load after tooth surface modification optimization is significantly weakened compared with that without modification optimization,and the minimum value of meshing impact after modification optimization is greatly reduced.When the input torque decreases or the amount of modification increases,the contact teeth surface imprinting of the meshing domain shrinks,and the sudden change of the impact load during the single-tooth and double-tooth meshing conversion is gradually significant,and the impact load between the interfaces is offset at the the meshing-in or meshing-out.(3)The contact characteristic model and interface friction dynamics coupling model of meshing gear pair with different contact interface micro-texture(Contact Interface MicroTexture,CIMT)morphologies are established,The contact interface micro-texture(Contact Interface Micro-Texture,CIMT)shape meshing gear pair contact characteristic model and interface friction dynamics coupling model are established.Considering the influence of gear meshing CIMT on the distribution type of hydrodynamic lubricating oil film,contact viscous damping,and frictional thermal load,the aforementioned models have involved time-varying meshing stiffness and static transmission error.Based on the proposed models,an example verification of meshed gear pair(MGP)is analyzed to reveal the influence of CIMT on the dynamic characteristics of MGP under a variety of micro-texture configurations and input branch power and rated speed/shaft torque conditions.Numerical simulation results indicate that the influence of CIMT on gear dynamic response(including meshing interface frictional thermal load,malicious damping,and impact vibration in the off-line direction of the action)is extremely restricted by the transient contact regularity of the meshing gear surface.Meshing gears dynamic characteristics(especially vibration and noise)can be obviously and effectively adjusted by setting a regular MGP with CIMT morphology instead of random gear surfaces.(4)Based on the formal decoupling method of macro-scale and micro-scale,the micro TEHL dynamic pressure contact model of micro element homogenization is introduced.Considering the deformation caused by compression bearing and thermal effect that cannot be ignored on the micro scale,the numerical simulation model of textured micro-element(Textured Micro-Element,TME)load-bearing contact of thermal elastohydrodynamic lubrication interface is proposed,and the effective friction reduction and anti-thermoelastic scuffing load bearing(Anti-Thermoelastic Scuffing Load Bearing,ATSLB)capacity between random rough meshing teeth surfaces(Meshing Teeth Surfaces,MTS)are presented,the mechanism linking interfacial thermoelastic lubrication,TME meshing friction reduction and ATSLB is revealed.The real contact domain area between MTS with multi-scale microelement textures(Micro-Element Textures,MET)is obtained for the numerical calculation of the three-dimensional equivalent TME contact volume,which is the correlation bridge between friction reduction and ATSLB of the thermoelastic lubrication interface.The proposed theoretical model predicts the time-varying behaviour of the textured meshing interface friction reduction with TME contact load under thermoelastic lubrication conditions.Numerical simulations show that the textured interface meshing volume is the key to solving the loadbearing problem of line contact between randomly rough teeth surfaces.The friction coefficients of the MTS are reduced by 13–24%.The lubricated load-bearing and friction reduction behaviour between the textured MTS is quantified by the thermoelastic voids of TME interface and actual meshing volume ratio,which provides a new perspective for further insight into the lubrication and friction reduction behaviour between the MTS with multi-scale MET-ATSLB coupling mechanism.