Research On The Mechanism Of Gas Hole And Crack Formation In Gear Remanufacturing Based On 3D Printing

3D printing is the essence of 3D solid in computer aided manufacturing.Its specific operation is to process solid model based on simple slice,then convert the manufacturing of 3D solid into the accumulation of 2D plane,calculate 3D solid along the direction of continuous superposition,and then combine 3D solid with 3D solid in computer aided manufacturing,so as to realize the automatic generation of 3D solid This is a unique advantage in the field of remanufacturing methods.Among them,laser cladding remanufacturing is a technical innovation in the field of remanufacturing.Laser cladding remanufacturing has the advantages of saving cost,reducing energy consumption,green manufacturing,etc.,but in the process of remanufacturing,there will be defects such as pores,cracks,carbides,etc.Therefore,it is very important to solve the existing defects while remanufacturing the laser cladding gear.In order to solve the problem of porosity and crack in gear cladding,a high hardness gear with 40Cr matrix is selected.According to the related materials,Ni60 Alloy is selected as laser cladding powder material.The main work and results are as follows:(1)Carry out three-dimensional scanning on the gear.According to the scanning results,compare and evaluate with the intact gear through the Geomagic control software.Use the ANSYS software and Unigraphics software for simulation and mechanical analysis,and propose the gear repair plan.(2)The process parameters of laser power,scanning speed and powder feeding speed are optimized through experiments,and the appropriate parameters are obtained according to the width,height and depth of Ni60 cladding layer.By using L9(34)orthogonal experiment,the range analysis of shape coefficient,dilution rate and crack rate is carried out,and the best single pass process parameters are obtained.(3)Based on the experimental results of multi-layer,theoretical calculation and measurement,and considering the micro morphology,while obtaining the center distance of transverse lap ratio and the lifting amount of longitudinal lap ratio of Ni60 powder,the causes of porosity and crack are analyzed,the crack ratio is calculated,and the hardness of cladding layer is measured.The element composition and morphology of cladding layer and crack were analyzed by SEM,and the best parameters of cladding effect were selected.(4)The effect of different MgO content on Ni60 cladding layer was studied to determine the optimal MgO powder content.Through the multi-layer cladding experiment,the causes of microstructure,porosity and crack under different height,morphology and parameters are analyzed,the crack rate is calculated,the hardness of cladding layer is measured,and the element composition of cladding layer and crack is analyzed by SEM,so as to obtain a better cladding layer,make its surface flat and reduce the defects such as cracks and pores.(5)The laser powder is Ni60+1%wt MgO,and the cracks and depressions in the coating are analyzed.Using the variable power method to remanufacture the gears.