| Surface projection moulding technology generates profiles by dynamic mask and solidifies a profile by one exposure.However,excessive adhesion between the cured layer and the constraining substrate may lead to peeling failure.The existing methods to reduce the adhesion force include over-curing,intermediate coating and changing the force direction of the cured layer,but these methods have their limitations and are difficult to be applied on a large scale.Continuous liquid interface production(CLIP)makes use of the oxygen inhibiting effect to reduce the adhesion force between the cured layer and the constraining substrate greatly,which makes it possible to rapidly manufacture large cross-section parts.Aiming at the high cost of this technology and the dificulty of filling liquid resin,this thesis presents a low-cost scheme of realizing the oxygen inhibition layer with porous transparent support plate and PDMS membrane.Based on the analysis of the formation mechanism of the inhibition layer,theoretical and experimental studies are carried out on the light transmittance and gas permeability of the substrate and the laws affecting the inhibition layer and adhesion force.The main,contents and conclusions of this thesis include:(1)Using FDTD Solutions software,the calculation model of constraining substrate in forming chamber was established,and the law of influence of micro-characteristics of constraining substrate in forming chamber on light transmittance was numerically simulated.The results show that the shape,size and distribution period of the microstructures introduced in the Surface projection moulding technology affect the transmittance of the substrate.The reasonable distribution of half-wavelength circular holes can effectively reduce the influence of microstructures on the transmittauce of the constraining substrate.(2)Constraining substrate with different micro-geometric characteristics were prepared.The effects of micro-geometric characteristics of substrate and technological factors such as light intensity and oxygen concentration on the thickness of oxygen inhibition layer were studied by measuring the transmittance and oxygen permeability of substrate and measuring the thickness of oxygen inhibition layer with the method of differential thickness.The results show that the microscopic characteristics only affect the transmittance and oxygen permeability of the constraining substrate,but have no obvious effect on the uniformity of the transparency of the constraining substrate.The thickness of the oxygen inhibition layer can be controlled by adjusting the oxygen concentration,light intensity and the microstructural characteristics of the substrate.(3)The effect of different printing conditions on the adhesion of the cured layer on the substrate was studied by 3D printing test.The results show that the inhibition layer can be formed with constraining substrate in this paper,and the thickness of the inhibiting layer can be affected by the substrates and oxygen supply conditions,thus the separation force can be affected.Compared with the traditional constraining substrate,the constraining substrate proposed in this thesis can significantly reduce the separation force of the cured layer when separation from the substrate. |
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