| Sliding screw pair has simple structure,low cost and wide application.But its transmission efficiency is low.The existing steel backing transmission nut with high efficiency and strong bearing capacity takes epoxy resin as the matrix,carbon fiber cloth as the reinforcement,the prepared lining layer is used to reduce friction,and steel is the nut matrix to support and load transfer.The sliding screw pair of carbon fiber（CF）lining composite material is prepared,which has low friction coefficient and high transmission efficiency.However,the surface quality of the nut is poor and the dimensional accuracy is low.The deviation of the thread will directly affect the efficiency of the screw transmission.Moreover,due to the use of carbon fiber cloth reinforcement,the secondary machining can not be used after the spiral surface is formed,and the accuracy can not be further improved.Polyether ether ketone（PEEK）is one of the thermoplastic materials with high temperature resistance,self lubrication,easy processing and high mechanical strength.The application of PEEK matrix composites is increasing gradually.Therefore,SCF/PEEK composites are used to prepare the lining of new transmission screw pair in this study,which not only ensures its accuracy,but also has good compression and friction and wear properties.In this thesis,the preparation method,mechanical properties and friction properties of SCF/PEEK matrix composites were studied,and the forming process of steel back nut was explored.Firstly,the molding preparation process of SCF/PEEK matrix composites was studied.Firstly,through comparison,SCF/PEEK powder with uniform distribution is obtained by using solution mixing;Through the thermal performance test of the material,it is concluded that the glass transition temperature of the material is 157.43℃,the melting temperature is 338.48℃,and the starting decomposition temperature is507.03℃,and the molding process parameters are preset;By testing the impact and Tribological Properties of the samples prepared with different molding process parameters,it is finally determined that 360℃for 30 minutes is the best molding process parameter.The material ratio was preset,and samples with different ratios were prepared.Secondly,the effect of the composition of SCF/PEEK Composites on the mechanical properties was explored.The Vickers hardness,impact properties and compression properties of samples with different formulations were tested to explore the influence of material composition on mechanical properties.The test shows that the addition of SCF and PTFE has different effects on the mechanical properties of the material.SCF can improve the mechanical properties of the material,while the addition of PTFE will reduce the mechanical properties of the material.Through comparison,PEEK/10ptfe/10scf is the material composition with the best comprehensive mechanical properties,with Vickers hardness of 45.1HV,impact performance of 19.43KJ/m~2 and compression performance of114.9Mpa,which meets the performance requirements of lining materials.Thirdly,the friction and wear properties of SCF/PEEK composites were studied.Through the dry friction test of samples,the effect of material composition on the tribological properties of materials was studied.The test shows that the addition of PTFE and SCF can increase the heat dissipation performance of the material and keep the material stable in the friction process.The addition of SCF will improve the friction coefficient of PEEK matrix composites,but improve its bearing capacity and reduce the wear.The addition of PTFE can reduce the friction coefficient of the material,but the mechanical properties of PTFE are poor,which will increase the wear of the material.Finally,combined with the friction coefficient and wear amount,it is concluded that PEEK/10PTFE/10SCF has the best tribological performance,with a friction coefficient of0.126 and a wear amount of 343.01μm~3.Finally,the preparation process of SCF/PEEK composite lining nut is explored.The bonding performance between SCF/PEEK liner material and steel back was studied.In order to improve the bonding between liner and steel back nut,PPS coating was prepared on the internal thread surface of the nut,and its bonding force was tested as an intermediate bonding layer.Compared with the previous research results of the research group,it meets the application requirements;Using the optimized molding process and material formula,the steel back nut was prepared.By improving the compression mode,the nut with dense lining structure was prepared from one-time cold compression to multi-stage compression.The secondary processing of nut was explored to improve the dimensional accuracy of the inner surface of nut,and finally the sample of steel back/PEEK matrix composite lining transmission nut was prepared. |
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