Study On Temperature Field And Stress Field Of The Fused Deposition Molding Process

Fused deposition is an important rapid prototyping technology developed in recent decades.It has been widely used in the fields of medicine,product design and development,mold manufacturing and design,and art creation.in the process of fused deposition modeling,because of the characteristics of the bonding between the cooling and solidification of the wire and the melt,a large temperature gradient is formed between the layers.The internal stress caused by the inconsistency of cooling and shrinkage of thermoplastic materials.Stress can cause warpage and cracking.Affect the accuracy and quality of parts.Therefore,based on the simplified assumption,this paper establishes the model of stress warping deformation.The temperature field and stress field in the process of forming are analyzed by ANSYS,and the temperature measurement experiment is carried out.The mutual proof between the theories,numerical simulation and experiment.This not only has important theoretical significance,but also has important application value.This paper mainly studies the following aspects:(1)In this paper,the numerical simulation of the temperature field of the nozzle is carried out.The results show that the nozzle is a steady temperature field,and the temperature of the molten wire is constant.The type of heat source load for transient temperature field of melting deposition was determined.(2)A finite element model for numerical simulation of melt forming process is established,and the properties and constitutive relation of ABS material are analyzed.by using APDL language and the technology of birth and death,the scanning path is designed and the load and boundary conditions are set up.The numerical simulation process can achieve material accumulation,heat source movement,boundary change.which is consistent with the actual melting deposition process.(3)From the microscopic point of view,the bonding mechanism of wire is analyzed,and the causes of stress and warpage and the influence of interface temperature on the stress are studied.Based on the mechanism of internal stress,a simplified stress model and warpage deformation model are established,and the influence of interface temperature and other factors on the stress and warpage is analyzed quantitatively.It provides the direction for the analysis of complex temperature field and stress field.(4)The numerical simulation of the temperature field in the process of melting deposition is carried out at 5mm/s,10mm/s and 15mm/s scanning speed,The results show that the temperature distribution law of the forming parts in the process ofaccumulation.The variation of the temperature curve of the node on the stack layer is regular,and it is affected by the process parameters such as the temperature of the molding chamber,the scanning speed,the convective heat transfer and the size of the workpiece.All of these parameters are reasonable,the lower the scanning speed is,the higher the interface temperature is.Based on the analysis of the temperature field,the stress field coupling analysis is carried out on the basis of the thermal elastic plastic theory.The stress of the workpiece is obtained at different scanning speed.The slower the scanning speed is,the smaller the stress is.Combined with the results of temperature field,the stress model is proved.(5)Finally,the experimental scheme is designed temperature fused deposition molding process,nozzle working temperature value measured by the data acquisition system,under different scan speed,the central position of temperature change data acquisition process of the first layer accumulation.The temperature curve and the measured temperature of the fused deposition modeling are compared,and the results are consistent with the simulation results of the temperature field.