Research On Remanufacturing Process Of Spur Gear Based On Laser Cladding

The application of laser cladding technology in remanufacturing is a technological innovation and a breakthrough in traditional processing methods.Laser cladding technology has the advantages of saving cost,reducing energy consumption,processing flexibility,and green manufacturing.In addition,its advantage in remanufacturing is also reflected in its short manufacturing cycle and its application to unexpected situations.Gear is the main part of mechanical transmission,so the research on gear remanufacturing is of practical significance.This paper focuses on the study of laser cladding process of high hardness gear which the matrix is 20CrMnTi.Based on the hardness,thermal expansion coefficient,elastic modulus and melting point of the materials,Fe based and nickel based metal powders were compared.Finally,nickel based Ni60 metal powder was chosen as the experimental material.This paper compares the two commonly used laser cladding methods of preset and powder feeding,and chooses the coaxial powder feeding process.The principle of laser near net shaping(LENS)is adopted to carry out experiments.The main work and results are as follows:(1)The gear's mechanical analysis and Ansys simulation are carried out to study the friction,stress and deformation of the working gear,and a better laser cladding scheme is put forward.At the same time,the area of the cladding layer,the pool area and the dilution rate of laser cladding are theoretically deduced,and the theoretical model is obtained.(2)Single factor experiments were carried out to rough selection the gas carrying capacity Q,laser power P,powder disk speed VP,scanning speed Vs.The comprehensive consideration the elements of dilution rate is 20%-30%,the aspect ratio is greater than 2 and the micro section morphology of the cladding layer is to make a choice the better parameters.Three levels of each parameter were selected to carry out three level four factor orthogonal experiment.Because of considering the multiple factors,L18(37)orthogonal table was used to carry out experiments.Range analysis is used to find out the main factors and secondary factors.Considering the possible interaction of experimental parameters,a full factorial interaction experiment was conducted to verify whether interaction exists and whether interaction is obvious.The parameters are optimized on the basis of the main interaction.The final parameters are Q=7.5L/min,the scanning speed is VS=9.5mm/s,the speed of the pulverized disk is VP=0.6r/min,and the power is P=370W.(3)Choosing the better parameters of multi-channel and Multichannel parameters:the parameters range of crosswise and longitudinal lap are obtained by theoretical calculation,and then the corresponding parameters are tested and compared according to the fluctuation of the calculation results.Considering the micro morphology and parameters,we can get the center distance D1=1.1mm of the lateral lap ratio and the lifting capacity of the longitudinal overlap?Z=0.3mm.Thermal lap,cold lap and Optimal cold lap are considered in lap mode.Hot lap is selected according to the surface roughness and microstructure by comparing the experimental parameters.For the scanning mode,two schemes are taken into consideration of the same direction scanning and the different direction scanning.Because of the uneven surface of the same direction scanning,the protruding and the collapse of the two ends are worse than the different direction scanning,so the different direction scanning mode is preferred.(4)The experiment of gear remanufacture is carried out.First,the tooth profile path is made by Robort Art software,and then laser cladding is carried out with the preferred parameters.During the process of cladding,the cracking of cladding layer and matrix appeared because the hardness of material and matrix was very large.Therefore,five experimental schemes are proposed,and the best scheme is selected by laser cladding experiment,and the damaged gear is cladded.Then the gear is processed.In the end,the gear samples were grinded,polished and corroded,and the internal structure and morphology were observed and analyzed,and then the hardness of the gears was tested to see if they meet the requirements of the use.