| With the improvement of people's living standards and increased demand for electricity,the power industry continues to develop.The most serious challenge of transmission lines power fittings,which are important part of the power industry,is the weight of power fittings getting greater,and how to realize the weight reduction.At the same time,looking for efficient and clean production process are also important.Therefore,we must adopt new materials,new technology to develop innovative new power fittings.This paper innovatively proposes the concept of multilayer hot stamping power fittings,which is combined ultra-high strength steel hot stamping technology with design and manufacture of new electric power fittings.The use of sandwich plates hot stamping instead of traditional connection power fittings casting and forging forming aim at developing high-mechanic strength,lightweight and reliable,low cost and timesaving new power fittings.The mainly contributions of this thesis include the following aspects:(1)Two typical connected electric power fittings Yoke plate and Z-twisted ClevisClevis are taken as the research object,and a new structure in accordance with new manufacturing process is carried out.In order to verify the feasibility and superiority of the new type power fittings after hot-dip galvanizing,the mechanical load performance simulation based on ABAQUS and the hot stamping thermo-mechanical-phase transition coupling finite element analysis based on LS-DYNA are carried out.The results show that the strength of the new type fittings can meet the bearing requirements with a large safety margin;the hot stamping process of the Z-twisted Clevis-Clevis can obtain uniform high strength and have the feasibility of forming.(2)The key technology of the new fittings forming is the multilayer plates hot stamping integrally.Cooling curves and the mechanical properties of the laminates under different contact pressure and different numbers of laminates are studied,It is found that The cooling rate of each layer increases obviously with the increase of contact pressure from.10 MPa to 40 MPa,The final strength of each layer basically remain the same;when the number of laminates increase from two to four,microstructure of plates change from martensite to mixture of martensite and bainite,the final strength change from 1500 MPa to 1000 MPa.Finally,the optimum process criterion for multilayer plates forming is proposed as double layer(3.6mm).It is necessary to avoid the formation of four layers plates(7.2mm).(3)Based on the simulation and heat transfer experiments,a double-layer hotstamping deep-U-shaped mold is designed and a forming process is carried out to obtain a component with uniform high strength,uniform thickness distribution,little spring back and high forming precision.Research the corrosion resistance of the new fittings,it is found that the hot dip galvanizing will reduce the strength of the fittings to 1000 MPa and increase the elongation to10%,which makes the fittings obtain better comprehensive mechanical properties.Finally,the mechanical load performance of new type power fittings is tested according to the national standard.The results show that the new type Z-twisted ClevisClevis can meet the bearing demand with a weight loss of 41%.This study put forward important data and conclusions of the feasibility of multilayer hot stamping power fittings. |
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