Research And Implementation Of SLA Variable Spot Scanning Method

As a production technique with high DOF(degree of freedom)and high forming precision,SLA(stereolithography apparatus)has become more and more popular in prototype,automobile,medical,shoe model and other industries.It is the most widely used industrial 3D printing technology at present.However,compared with the traditional material reduction and mold-based manufacturing technology,SLA still has the disadvantage in production efficiency.Therefore,improving printing speed has been significant for SLA development.Variable spot method is a new optimization method for efficiency improvement,whereas many researches are lack of the overall study of variable spot technique and corresponding path planning,which result in the problems of forming quality reduction and unsatisfactory acceleration.This paper studies SLA from four aspects: Variable spot control system design,the scanning path planning,the software development and the forming experiment.The first step is to design variable spot scanning control system based on the existing system of SLA.On this basis,analysis of spot curing energy can be done so that the variable spot stroke is calibrated to determine the size of different spots.In the second step,a continuous variablespot scanning path algorithm is proposed aiming at the problem of filling gap caused by the size of spot in the existing scanning mode of variable-spot.The algorithm divides the area to be scanned into three areas: the first region,the second region and the third region.The first region uses the minimum spot scanning processing;the second region uses the maximum spot scanning processing;in the third region,the scanning radius of laser spot is gradually increased and processed step by step.Continuous changes of each region are carried out according to the gradual increase or decrease of spot radius in the scanning process and realize continuous variable-spot scanning processing.Moreover,the partition optimization is carried out based on the characteristics of the spot path,which further improves the quality and efficiency of the forming.In the third step,the variable-spot SLA software is developed.According to the diversity of the variable spot modules in the SLA software,the variable spot function is extended to the SLA software as a plug-in,then the variable-spot path planning module is designed through the factory method pattern.The fourth step is to carry out the forming experiment verification on the finished variable spot curing software.Compared with the traditional variable spot path scanning,it significantly improves the forming quality and improves the local overheating curing of parallel scanning variable spot path forming.The achievements described in this paper have been verified and successfully applied in many industrial SLA machines,which are widely used in the production fields such as prototype and shoe mold.