Research And Implementation Of Model Forming Direction And Supporting Structure For Additive Manufacturing

Additive manufacturing is commonly known as 3D printing.Because of the principle of layer-by-layer superposition,it differs greatly from the traditional manufacturing method of reducing material.In view of the drawbacks of Reduced material manufacturing,such as unsuitable for single workpiece production,unable to process complex workpieces,and accompanied by the increase of personalized needs of all walks of life,people pay more and more attention to the technology of Additive manufacturing.Additive manufacturing technology eliminates the process of die development,shortens the whole cycle of a single part from design to forming,and breaks through the limitation of complex structure on the processing process.In this paper,the forming direction and supporting structure which have important influence in the process of Additive manufacturing are studied.Forming direction will affect the surface quality,forming speed and support quantity of the model,but the above three evaluation criteria often can not reach the optimum in the same forming direction.Therefore,the selection of the forming direction of the model should take into account many factors such as actual demand,model characteristics and so on,in order to find a better solution to meet the requirements.In this paper,the three evaluation criteria of forming direction are quantified as model volume error,forming time and support volume,and the corresponding mathematical model is established.Finally,the single objective optimization of forming direction is solved by using MATLAB and genetic algorithm to verify the accuracy of the mathematical model.Under the same forming direction,the influence of different support structures on the forming process is different,especially on the forming speed.In this paper,the support structure is studied from the stability and the forming speed.The concepts and the extraction algorithm of the suspension surface,the suspension edge and the suspension point are introduced in detail.The focus is on the study of the large number of suspension surfaces in the model.Starting from the concept of critical angle of support,an algorithm for generating conical support structure based on material self-supporting is proposed.The conical support is generated successively for triangular facets that need to be supported,and the solution to the problem of intersection of supports is given.The new concepts of the basic support point,the foundation support body and the feasible region of the support point involved in the algorithm are elaborated in detail,and the detailed mathematical deduction process is given.Finally,the feasibility of the algorithm is verified by an example.Considering the surface quality,forming speed and support quantity,NSGA-II and linear weighting method are used to solve the multi-objective optimization of the forming direction,and the interface for the optimization program is compiled for user.Finally,the support structure designed in this paper is used to participate in the optimization process of NSGA-II.The calculation results show that the support structure can be used to decouple the support factors in the multi-objective optimization problem of forming direction.