Key Technology Research Of Large Format 3D Printing Control System Based On Continuous Liquid Interface Production

The 3D printing process based on continuous liquid surface extraction technology(CLIP)is designed based on the principle of photopolymerization reaction of liquid photosensitive resin under ultraviolet light and oxygen-blocking reaction in an oxygen-rich environment,and the 3D model entity is constructed by sequentially superimposing resin curing layers through projection equipment that continuously projects digital mask images onto the surface of liquid resin for selective curing.The difficulty of continuous forming of large-format 3D models is the key point that restricts its development and application.This paper firstly proposes a design scheme of CLIP large-format 3D printing control system based on fixed stitching;then investigates the optical distortion generated by combined stitching projection to eliminate the surface seams of model entities;finally,combining the light-curing characteristics of liquid resin and the forming principle of CLIP,the paper deeply analyzes and explores the advantages of CLIP-based continuous forming of largeformat 3D models.Finally,we analyze and explore the solution of continuous molding of large-format 3D models based on CLIP.The main contents of this paper are as followsIn response to the problem that the molding area of CLIP-type 3D printers is limited by the size of projection devices,a fixed splicing molding scheme is proposed to expand the molding area by tiling multiple projection devices.Compared with the method of using a single projection device to move and splice,this solution has less mechanical errors,faster molding speed,and less work to calibrate and maintain the accuracy of mechanical equipment.Based on this solution,we designed and implemented a fixed splicing type CLIP printing control system,and laid the foundation of hardware and software platform for the subsequent research.An edge energy homogenization distortion elimination scheme is proposed to address the problem of seams in model entities caused by optical distortion generated by stitching projection.The solution modifies the model slicing process in the 3D printing process,divides each layer of the sliced bitmap into multiple small-sized unit bitmaps that can be projected by a single projection device according to the stitching pattern of the projection device,and adjusts the overlapping pixel values at the edges of the unit bitmaps to eliminate the optical aberrations caused by the overlapping pixels on the projection surface,ensuring a uniform and consistent UV intensity on the projection surface and solving the problem of seams on the solid surface of the model.It also provides a good support for the continuous molding of large-size 3D models.In response to the difficulty of continuous forming of large-format 3D models based on CLIP,a scheme of continuous forming of large-format 3D models with adjustable light intensity on the projection surface is proposed.The scheme improves the light curing process in the CLIP printing control process by modulating the UV light intensity of the imaging system in time sequence,using variable UV light intensity instead of the traditional single UV light intensity to cure each layer of slices,and achieving a balance between the liquid photosensitive resin curing speed and reflow filling speed during the continuous molding of large-format 3D models,which can effectively improve the success rate of the preparation of large-format 3D models based on CLIP.The success rate of CLIP-based 3D model preparation can be effectively improved.Through detailed experimental testing of each unit of the system and evaluation of the final molding samples,it is demonstrated that the CLIP-based large-format 3D printing control system designed in this paper has all reached the expected level.At present,it has entered into the equipment trial operation stage with good function and normal operation.