Research On Forming Process And Forming Quality Of Laser Cladding Variable Width Thin-walled Blade

Since China proposed the development strategy of "Made in China 2025 ",the strategic position of the aviation industry has become increasingly important.The performance of aero engines is largely affected by the manufacturing level of the blades.The main characteristics of today’s blades are large curved angles,thinner thicknesses and flexible changes.These characteristics make it difficult to process using traditional methods.The laser cladding forming technology has become a better method for forming blades at present because of its characteristics of forming complex structural parts and difficult-to-machine materials.However,for the current laser cladding forming technology based on optical coaxial coaxial powder feeding,it is still difficult to meet the requirements of flexible changes in blade width.The main reason is that laser cladding based on coaxial powder feeding is limited by the diameter of the laser spot,and it is difficult to change the melt channel width in real time.If the overlap rate is changed to achieve variable width,it is very easy to cause uneven height of the cladding layer due to the change of the overlap rate,and eventually lead to forming failure.Therefore,the research on the variable-width laser cladding forming process is of great significance.Therefore,a new laser cladding variable width forming method is proposed in this paper,which realizes variable width thin-wall forming through multiple overlaps and changing the overlap rate and scanning speed in real time,and the relevant mathematical model is established to solve the problem of variable width thin wall forming based on coaxial powder feeding.In this paper,Inconel718 alloy powder is used as a raw material,and a laser cladding device based on optical coaxial powder feeding is used as an experimental device.The feasibility and effectiveness of this forming method are studied through a combination of theory and experiment.In addition,the temperature field and geometric morphology during laser cladding were simulated and verified by experiments.Subsequently,the microstructure and properties of the thin-walled parts with variable width were studied.Finally,the laser cladding of the blade was completed.The main contents is summarized as following:(1)Forming method and theoretical study of variable width thin-walled parts.The variable width forming method was studied,and the relationship model between the scanning speed,the overlapping rate rate and the Z axis increments in the variable width thin-wall single layer and multi-layer forming process was established.Provide theoretical data support for the selection of process parameters for variable width thin wall forming.(2)Temperature field simulation of variable width thin-walled parts.The finite element simulation model of laser cladding forming was established.The moving mesh method was used to simulate the single-pass and single-channel multilayer laser cladding forming process,and the geometrical shape and temperature field distribution were studied.Corresponding experiments were carried out,and the actual temperature change process was measured using a thermocouple.The geometrical appearance and temperature distribution of the simulation and experiment were compared to verify the accuracy of the simulation results.Then use this simulation method to simulate the variable width forming process,and study the geometric shape and temperature field distribution during the variable width forming process.(3)Experimental research on variable width thin-wall structure cladding forming was carried out.Using the theoretical process parameters obtained in the first part,the single-layer and multi-layer variable-width structure forming experiments were carried out respectively,and the feasibility of the forming method proposed in this paper and the accuracy of the theoretical model were studied.The forming of thin-walled parts of different width ranges is carried out,and the practicality of the method of variable width forming and its forming accuracy are studied.(4)Research on microstructure and mechanical properties of variable width thin-walled parts.When forming a workpiece,not only the geometric dimensions are required,but also the microstructure and mechanical properties are required.Therefore,this part mainly studies the microstructure and tensile properties,hardness and other mechanical properties of the variable width molded parts.The effect of changing the overlapping rate and scanning speed on the microstructure and mechanical properties of the formed parts was analyzed.Therefore,it is further studied whether the forming quality of the formed part obtained by the forming method satisfies the requirements.(5)Research on torsion thin wall forming and laser cladding forming of blades.A torsion thin wall experiment was conducted to study the maximum inclination of the torsion thin wall forming.Prepare for subsequent blade torsion forming.In this part,combined with the results of the previous sections,the process parameters selection and path planning for thin-wall variable width blade forming are carried out.The blade is then formed.The forming precision of the formed blade is tested to evaluate the blade forming result.