| As an effective way and means to improve train speed and ensure braking performance,laser cladding technology can strengthen brake disc of the high-speed train.The laser cladding technology can prepare good wear-resistant layer,but the it can make oxide scale and residue on the surface during the manufacturing process.If the impurities on the surface of multi-layer laser cladding are not cleaned up,the performance of laser cladding layer will be damaged.Therefore,this study used Fe-based alloy to make layer for high-speed train brake disc by laser cladding layer,and a set of material reduction milling device was designed and assembled.The solid brake disc was formed by the technology of additive and subtractive manufacturing.Firstly,according to the material and service requirements of brake discs at home and abroad,a new type of laser cladding iron-based alloy powder was designed.The technological parameters of laser cladding were studied by orthogonal experiment.The results show that the scanning speed has the greatest influence,the laser power has the less influence,and the powder feeding quantity has the least influence.The optimum technological parameters are 600 w,speed is 4.5mm/s,and the powder feeding voltage is 6r/min.Furthermore,the effect of different single-pass lapping ratio on laser cladding layer of brake disc was studied.The results show that 60% of the single-pass lapping ratio has smooth surface and no cracks.The microstructure of laser cladding sample is fine and uniform lath martensite with micro hardness of 359.68 HV;tensile strength is 1172 MPa,elongation is about 12.1%,and there are a large number of second phase strengthening particles in the tensile fracture;friction factor is 0.339,the wear mechanism is a mixture of fatigue wear and oxidation wear,and the main performance indicators meet the requirements of the brake disc.Secondly,before forming the brake disc of high-speed train,in order to remove the oxide scale and residue on the surface,a set of automatic material reduction device was designed and developed: the assembly of the moving device was completed by using the base,moving shaft,gantry frame and electric drill,and the stability of the device was simulated by using Workbench.The overall stability of the device is good,meeting the stability requirements of material reduction by using the control card.The hardware system is built with the driver and the corresponding motor and circuit.The overall matching of TD-LCD software realizes the movement and milling control of the material reduction device.The results show that the surface quality of the sample is improved,the interlaminar inclusions are narrowed,and the laser cladding layer hardens under the action of cutting tools,which leads to the improvement of the hardness of the brake disc of high-speed train,and the internal and external quality meets the forming requirements of the brake disc.And the comparative experiment was carried out with the mechanical reducing device.The results show that the surface quality of the sample after reducing material is improved,the interlinear inclusions are narrowed,the hardness of the laser cladding layer is improved under the action of cutting tools,and the internal and external quality meets the forming requirements of the brake disc.Finally,ANSYS finite element software is used to optimize the forming path of the brake disc.The growth process of cladding layer is simulated by using life and death element technology,and the energy of laser is simulated by generating heat source inside.The whole disc is divided into 6,8 and 12 sectors for sequential and sequential simulation.The results show that the deformation and residual stress of 12 pieces are the smallest when scanning sequentially.Using the above laser cladding process parameters and material reduction milling technology,combined with the numerical simulation path,the 1:1 high-speed train brake disc was manufactured.The laser cladding layer thickness on the surface of the brake disc was 4 mm. |
PDF Full Text Request