Research On Forming Process And Mechanical Properties Of Parts Fabricated By Addition And Subtraction Hybrid Manufacturing

Addition and subtraction hybrid processing technology is an advanced manufacturing technology combined with the Coaxial Powder Feeding Laser Cladding and 5-axis(or 3-axis)CNC vertical processing technology.It is a layered manufacturing technique that shapes a three-dimensional solid model based on successive steps of additive deposition and cutting.This paper introduces the principle and characteristics of the hybrid processing technology of the addition and subtraction,and analyzes the forming mechanism and mechanical properties of the current parts by manufacturing in the hybrid processing of the addition and subtraction.Combining the research needs and practical problems of the hybrid processing system for the addition and subtraction,the laser/metal thermal interaction and the metallurgical kinetics of the molten pool are described.Finite element numerical analysis was used to simulate various factors affecting forming accuracy and efficiency,including laser power,single layer height,powder feeding rate,scanning speed,etc.;Revealing the interaction discipline between the appearance of the cladding and texture properties by observing the surface contour shape,surface finish and microstructure;For different process conditions,the tensile strength,elongation,tensile fracture,yield strength,stress strain,residual stress of the parts were measured.The influence of hybrid forming microstructure on mechanical properties was studied,and the comparative analysis of mechanical properties of addition,subtraction and addition and subtraction parts was carried out.In the end,the verification was carried out using a hybrid processing system for the addition and subtraction.The specific research contents are as follows:1.Describe the thermal interaction of laser/metal powder and metallurgical kinetics of molten pool.A theoretical mathematical model and a three-dimensional transient finite element model of the laser metal deposition process were established.2.Using the commercial finite element software Solidworks,Hypermesh,Simufact welding to form a joint simulation of the process chain,developing and studying the temperature evolution in the single-line multilayer laser metal deposition process,and defining the specific critical temperature in the thermal process.The distribution of temperature gradient and thermal stress-strain in the sample was discussed.3.The orthogonal experimental design of the addition and subtraction was carried out.Six variables of laser power,powder feeding rate,scanning speed,single layer height,spindle speed and milling speed were studied using a 6-factor 5 level orthogonal test table.The results of the forming precision and forming quality of the parts were obtained.The optimum process parameters were obtained by comparing the forming quality and microstructure of the formed parts under different process conditions.4.Research on the mechanical behavior of the hybrid processing parts of the addition and subtraction.The local geometric structure of the non-uniform phenomenon of addition and subtraction hybrid forming parts under different process conditions is explored,and the following research is carried out:the relationship between process parameters,process conditions and residual stress distribution on the surface of the parts during the hybrid processing of the addition and subtraction;The microstructure and mechanical behavior of the hybrid processing parts of the addition and subtraction;the influence of process conditions and heat treatment on the mechanical properties and microstructure of parts fabricated by addition and subtraction hybrid manufacturing5.The microstructure and microhardness of the formed samples under different working conditions were measured.The effects of different process conditions on the microstructure,microhardness and porosity of the samples were discussed in detail.