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

With the economic globalization, the market’s competition will be more and more ruthless and time-to-market of the products is a key success factor of the corporations. As a result, the enterprise will need more and more Rapid Prototyping (RP) equipments, which can increase the successful ratio of developing a new product, decrease the time and cost required for a new product development. Compared with other RP technology, bottom-up projection based Mask Projection Stereolithography (bottom-up projection based MP-SLA) has advantages on forming speed and accuracy. Consequently, bottom-up projection based MP-SLA has better developing potentialities and expansive applying foreground. It has fast been developing lately. But it is still in the development stage, the related domestic products are limited. It has very important practical significance and application value to do the research of its key technology. The main content of research in the paper is as following:This paper discusses the characteristics of bottom-up projection and up-bottom projection based MP-SLA. Researched the light energy distribution in liquid resins. And on this basis, analyzed the effect of the distribution of irradiance on the forming accuracy. Some problems of bottom-up projection based MP-SLA were optimized.According to the characteristics of bottom-up projection based MP-SLA, the project and structure of the mechanical system, controlling hardware system and controlling software system in the original equipment were designed. It was established the groundwork of the first bottom-up projection based MP-SLA equipment with our own knowledge right to be developed.The irradiance distribution model was obtained by measuring the irradiation intensity in various regions of the projection plane with a lumeter. Through this model, it is shown that the irradiance distribution was uneven. To solve the problem of the uneven distribution of irradiance, the bilinear interpolation algorithm is used to homogenize the irradiance distribution. Finally the effectiveness was validated through the part forming experiment. This method in a certain extent solved the problem of the uneven distribution of irradiance.The bottom-up projection based MP-SLA solved the cured resin warp problem, but it also has some defects such as the fracture of the tiny features. To solve this problem, the contour recognition and explosion compensation method was used. Explosion compensation time Ts was adopted by comparative experiment. At last the ring fabrication experiment proved effectiveness of this method.