Research On The Key Techniques Of Stereolithography Continuous Liquid Interface Production

With the development of process and materials,3D printing technology has slowly turn from simple prototyping to be more and more used to manufacture the end-use part.It is the intrinsic drawbacks of conventional 3D printing technology that low fabrication rate and the fact that building parts are not isotropic that limit the development and conversion of the technology.However,the emergence of continous liquid interface production(CLIP)has perfectly solved these issue.CLIP technology has attracted great attention since it came into being due to amazing processing efficiency and good processing quality.However,there are still some problems in the process.This paper aims to study the existing problems.This paper analyzes the principle in CLIP process and formation mechanism of dead zone.According to the principle of CLIP technology,the prototype machine is built.The mechanical system,software system and control hardware system of the protype machine are designed respectively,which lays a foundation for further research of CLIP process.In order to guarante successful during CLIP process,this paper researches on the model processing based on the CLIP process.The support structure which fits the characteristic of CLIP is designed and the algorithm that manually adds support for STL model is designed.To solve the problem of low resin filling efficiency in large cross-sectional area part of model during CLIP process,an algorithm for hollowing out the model and then automatically generating tree-shape support for the inside and outside of the hollow model is proposed.The hole problem in slice image that caused by intersection of support and STL model are solved successfully through imporved the traditional scanning line algorithm by distinguishing the inner and outer contours,and a defect-free image are generated finally.Experiments show that the algorithm not only can be built model successfully but also can improves the process efficiency and saves the material.Due to the dead zone too thin in the CLIP process,the resin filling efficiency is limited.Two process optimization schemes are proposed for resins with different viscosities in this paper.To solve the problem for small viscosity resin that the filling rate are different in the different cross-sectional areas part of the model,a variable-speed motion scheme based on part model information are proposed,which through the grayscale processing of the mask image,changes the irradiance of the projector to achieve the best curing accuracy of the part.The test results show that this method can maximize the flowability of the resin to acheive greater process efficiency without sacrificing accuracy.For the large viscosity resin that cannot be filled or the filling rate is too low in the continuous motion CLIP process.According to the parallel plate gap flow theory,a scheme that accelerates resin filling rate based on a rotating resin tank is proposed.The resin filling ability under this scheme were explored and it is proved that the scheme can effectively improve the efficiency of resin filling and the kind of resin filling by the experiment.Finally,the combination of the model hollowing algorithm and the variable speed CLIP process can further improve the process efficiency of the small viscosity resin.The comprehensi've methods of model hollowing,variable speed CLIP process and rotating resin disk process were used to build a model with a large viscosity resin,which can further improve the process efficiency and expanded the type of resin that can be used in the process.