Research On The Key Techniques Of Separation Process Of Bottom-up Projection Based Mask Projection Stereolithography

Additive Manufacturing(AM)is an advanced technology to fabricate complex 3D objects by means of layered accumulation process.AM has a lot of advantages,such as broad model sources,arbitrary complexity of the manufacturing objects,High personalization,high speed of forming,high material utilization,and it brings great impact to traditional manufacturing industry.These advantages enable the technology to make many new concepts come true,such as just-in-time manufacturing,personal manufacturing,food printing,and organ printing.Among the varieties of additive manufacturing technologies,Mask-Image-Projection-based Stereolithography technology can form the shape of a whole layer by one projection,and with the high efficiency,high precision and low equipment cost,gets a lot of attention and promotion from the market.However,there are still many problems in the process of this technology.In this paper,two kinds of forming methods of MIP-SLA process are discussed:bottom-up and up-bottom projection based mask projection stereolithography.Then the characteristics of the separation process of the bottom-up projection based mask projection stereolithography are discussed and the relationship between separation force and separation distance is studied by using the cohesion model.A separation model for the bottom-up projection based mask projection stereolithography has been established,and the relationship between separation force and separation distance has been simulated by finite element simulation.According to the characteristics of the bottom-up projection based mask projection stereolithography,the mechanical structure and the hardware has been designed,and combined with the software developed by our laboratory,3D printer of bottom-up projection based MIP-SLA has been developed.The relationship between separation force and separation distance under different velocities is obtained through experiment,and the comparison with simulation results illustrate that the relationship between separation force and separation distance follow the Bilinear Tension Displacement Law.The relationship between the separation force and the solidified layer area,shape has been obtained through experiments.Based on the change rule of separating force and separation velocity,solidification area,the improved method for separation was put forward and the experiments was carried out.Based on the change rule of separating force and separation velocity,solidification area,the improved method for separation was put forward and the experiments was carried out.