Research On Large-scale Thin-wall Structure Parts With Complex Surfaces For FDM 3D Printing

With the increasing market competition in automotive industry,personalization and diversification have become the development trend of the automobile in the future.How to shorten the research and development cycle and production cycle of automobiles has become the focus of major automotive companies.3D printing,also known as additive manufacturing and rapid prototyping technology,has been widely applied in the automotive industry,complex products,and innovative designs due to its ability to achieve arbitrarily complex structures and enable manufacturing rapidly.3D printing plays an extremely important role in the design and manufacture of many complex curved thin-walled structures such as automobiles by virtue of its ability to produce arbitrarily complex structures.On the one hand,on the 3D printing application side,large-scale fast 3D prints with guaranteed mechanical properties are rigid requirements;on the other hand,the manufacturing efficiency of 3D printing is directly proportional to the model volume.And at the same time,the volume of the printer and the uncertainty caused by the lengthy manufacturing process of large parts will greatly reduce manufacturing accuracy.Aiming at solving the problem of not being able to print large-scale models of complex thin-walled structures at one time,this paper proposes a set of model-based connection assembly methods based on FDM printers.The details are shown as follows:(1)For the FDM type 3D printing process,this paper adopts the “divide and conquer” strategy that considers the print volume,issues the printing principle of 3D printing technology and facilitates the subsequent assembly,then proposes a connection method of local thickened smooth transitional connection and glue application.Firstly,through the analysis of the main force form of the model,three-point bending experiment was performed on the connection structure,and the validition of the connection structure was conducted.Coupling force unit was used to simulate the adhesive connection between the two units.The finite element analysis was performed on the connection structure.The finite element model was verified by comparing the force-displacement curve between the experiment and the finite element simulation.In order to make the connection structure designed in this paper still have enough strength under the premise of light weight,the connection structure is further optimized in size.According to the Pareto solution set obtained by the optimization,the solution of both lightweight and strength is taken into consideration,which provides a technical basis for the “divide and conquer” assembly scheme.(2)For large model of thin-walled structures with complex surfaces,a segmentation algorithm framework with the above connection structure was proposed on the basis of Chopper segmentation algorithm.By decomposing large 3D models into smaller parts to fit the printer's print volume,the algorithm considers printability,the stability of the connection structure,the aesthetics of the connection gap after segmentation,and the print order of the output after printing.Taking the car body surface model and complex curved mouse head as examples,the above algorithm is used to complete the model print test.Through the analysis of examples,the segmented and printed model can not only complete the large-scale model printing,but also adopt the way that multiple printers print together,which greatly shortens the printing cycle.After proper segmentation,the support quality generated during printing is significantly reduced,which reduces the use of materials and printing costs.