Research On The Model Processing Technology Of Bottom-up Projection Based Mask Projection Stereolithography

3D printing technology is the emerging manufacturing technology in recent years.This technology has the advantages of high utilization of materials,can be processed any complex structure and easy to achieve personalized customization,and has brought subversive effect on the traditional manufacturing industry.Researches and commercial applications for 3D printing are in the ascendant.The 3D printing process is a kind of new printing method.Compared with the traditional 3D printing process,mask image projection stereolithography can realize the whole forming of the two-dimensional parts through a single irradiation.It has the advantages of fast processing speed,high precision,low cost and has drawn more and more attention.There are still many problems to be studied in the process from the principle to the model processing technology.The process principle of the two forms of mask projection stereolithography is analyzed.The characteristics of the two processes bottom-up and up-bottom projection based mask projection stereolithography are compared.The bottom-up structure of the solution is more simple and the printing precision is higher and selected as the main research object.The curing mechanism,curing depth and width control methods are analyzed,and the curing parameters of the resin are determined.A tree-shaped support generation algorithm based on three-dimensional model is designed for the problem that the columnar support structure could damage the surface,waste support material and the post-processing cost are high.According to the characteristics of the bottom-up projection based mask projection stereolithography,the critical angle,self-supporting radius and other parameters are determined by experiment.Experiments show that the support generated by the algorithm can reduce the amount of support while ensuring the stability of the structure.In this paper,the algorithm of distortion correction and eliminating the sawtooth effect through the mask image is designed.The image coordinates are obtained by image processing,and the improved scanning line algorithm is designed according to the world coordinates of the pixel.Based on the Gaussian distribution of the pixel intensity,the pixel gray value is calculated by the area weighting method.Compared with the traditional method,the straightness error and roundness error of the parts are obviously improved,and the sawtooth effect is greatly suppressed.The size and shape accuracy of the printed models are also improved greatly.