Research On Key Technologies Of Metal Mirror Based On Additive Manufacturing

With the continuous development of optical measurement and remote sensing,higher requirements are put forward for the weight,volume,rapid preparation and environmental adaptability of optical components.Because of its good processing technology and low material cost,metal mirrors are one of the choices for optical components of aviation optical equipment.In order to improve the structural rigidity of the metal mirror,achieve a higher degree of weight reduction,and at the same time make it suitable for the application in the visible light waveband,a scheme for preparing the metal mirror by additive manufacturing technology was proposed in this paper.In order to realize the preparation of additively manufactured metal mirrors and expand its application range,the material properties of laser selective melting and forming of AlSi10 Mg alloy,the preparation of additively manufactured mirror substrates,the modified layer of metal mirrors,the support structure of metal mirrors and lightweight structure have been studied.The main research contents and results are as follows:(1)The physical properties of the formed parts of additive manufacturing will be inconsistent in all directions,and pores may appear during the melting process of additive manufacturing,which will affect the stability of the mirror.These two issues are researched separately in this topic.In order to reduce the influence of thermal anisotropy of metal materials,the microstructure morphology and dynamic characteristics of the AlSi10 Mg alloy deposited by laser selective melting and heat treatment were studied in depth,and the microstructure of the heat treatment process was analyzed.The influence of morphology,phase distribution and thermodynamic characteristics was concluded,and it was concluded that the heat treatment of solution treatment and quenching reduced the anisotropy of AlSi10 Mg alloy.At the same time,the density of AlSi10 Mg alloy is improved,and the porosity of the sample can be significantly reduced after hot isostatic pressing.(2)The structural design of the additively manufactured metal mirror substrate was studied.The structural design elements that meet the additive manufacturing process are summarized.The mirror substrate was prepared according to the process flow,and it was densified and heat treated.The surface accuracy and surface roughness of the substrate of the additive manufacturing mirror are tested.The surface shape accuracy test before and after thermal temperature cycling was performed,and the mirror surface shape accuracy was successfully stabilized.(3)Because the additive manufacturing aluminum alloy AlSi10 Mg is composed of two materials with different hardnesses,it is difficult for ordinary machining methods to achieve high-precision surface finish.In order to solve this problem,the surface finish of the additively manufactured mirror is improved by depositing a modified layer on its surface.According to the requirements of environmental adaptability,a pure aluminum modification scheme with a thermal expansion coefficient similar to that of the mirror substrate is adopted.The modification process parameters are determined,and the optical mirror surface can be successfully processed and stabilized.The performance of the modified layer was tested and researched.(4)The design principle of the support structure of the metal mirror is clarified.Taking full advantage of the forming advantages of additive manufacturing technology,a tri-pod support structure suitable for metal aluminum alloy mirrors is designed.According to the elastic theory,the flexibility matrix of the tri-pod support structure is established.And through simulation analysis,the central single-point support mirror and the back three-point support mirror using the tri-pod support structure are analyzed.Tri-pod support structure can achieve better surface accuracy and smaller rigid body displacement.(5)Based on the above research,a model of aspherical metal mirror with a diameter of ?149 mm is established.The lightweight design of the mirror adopts an additive manufacturing lattice lightweight structure to achieve a high lightweight rate of 69.87%.The mirror is prepared by additive manufacturing and optically processed,and the RMS value of the mirror shape accuracy is better than 1/30?(?=632.8nm)and surface roughness is 1.95nm(RMS).In summary,key technologies such as the AlSi10 Mg material properties,the stability of the additively manufactured mirror substrate,the pure Al modified layer,the support of the mirror and lightweight structure are studied in this article.At the same time,the preparation of lightweight and high-rigidity aluminum alloy mirrors verifies the feasibility and effectiveness of additive manufacturing of metal mirrors.The research in this article provides a choice for the preparation of metal mirrors and provides effective principle basis and technical support for the preparation of additive manufacturing metal mirrors.It has important theoretical significance and application value to lay a foundation for the further promotion of the use of additive manufacturing metal mirrors in aviation,aerospace and ground-based optical detection fields.