CMT Additive Manufacturing Forming Process And Process Simulation Of Complex Feature Structural Parts

In recent years,with the rapid development of China's aerospace and ship fields,large-scale,lightweight and complex metal structure parts are widely used,higher requirements are put forward for the molding manufacturing process at the same time.Compared with the traditional manufacturing process,arc additive manufacturing has the characteristics of high production efficiency,low processing cost and good molding performance,which can directly shape the metal structure with compact structure.In this paper,the forming process of complex structural parts is studied,mainly through temperature field simulation analysis,improvement of forming method,establishment of prediction model and other methods.Firstly,the temperature field of CMT arc additive manufacturing process is mainly studied in the aspect of controllability.Based on the traditional double ellipsoid heat source model,the intermittent coefficient ? is introduced to modify the heat input frequency of heat source,and the CMT intermittent heat source model is established to effectively improve the accuracy of temperature field simulation.Using infrared thermal imager to design verification test.The test of the thermal cycle curve at the preset point of the substrate is compared with the simulation data,the results show that the coincidence is high,which verifies the validity of the simulation model;The numerical simulation model is used to simulate the temperature field of thin-wall surfacing process,study the effects of interlayer interval time and substrate preheating temperature on peak temperature,temperature gradient and cooling rate.The results show that the temperature gradient can be reduced and the cooling rate can be increased by changing the interval time between layers and the preheating temperature of the substrate.The temperature of the preform can be controlled by combining the cooling and heating to improve the manufacturing quality of the CMT arc additive manufacturing.Secondly,the research on the forming process of complex feature structure is carried out.A series of single weld forming tests are carried out,and a neural network prediction model is established based on the test data to accurately predict the forming size of single weld seam under different process parameters,thus realizing the closed-loop control of the manufacturing process of arc additive.Then,the forming path is planned based on the idea of vertical cross,and the defect rate is reduced.On this basis,a mathematical model is established to accurately predict the forming size of the preform and the inclination angle of welding torch in the process of surfacing.Finally,according to the basic test of arc additive manufacturing in the early stage,the range of process parameters suitable for CMT arc additive manufacturing is determined.With the high precision infrared thermal imager as the medium,the temperature field simulation analysis results,feature forming method,size prediction model and algorithm are combined with the forming system to carry out the forming test of some complex feature structural parts.The test results show that the surface of the preform is of good quality,no obvious defects appear,and the error of the forming dimension is less than 1mm,which meets the requirements of the arc additive manufacturing and forming,and verifies the validity of the theory.