Abstract: The rapid and personalized manufacturing of braces puts forward the demand for unsupported molding of 3D printed braces.In the process of unsupported printing needs to change the deposition direction,corresponding to the layering needs to change the direction of the tangent plane,the tangent plane between the angle will be generated.If the angle is too large,it will produce a step phenomenon;if the angle is too small,there is no more subdivided cutting plane between the two neighboring cutting planes,and the model between the two cutting planes can not be layered,resulting in part of the model missing when printing;both of these situations will have a negative impact on the mechanical properties and surface quality of the support printing.Aiming at this problem,a variable layer height planning and path compensation method for unsupported rapid 3D printing of the support is proposed.Through the extraction of the central axis of the brace model and the layer planning based on the central axis, the ladder phenomenon is avoided;for the lack of model caused by the change of the tangent plane, the amount of compensation is calculated,and the variable layer height path planning is used to compensate for the mechanical properties and surface quality of the brace;and finally five-axis printer printing Gcode file is generated. The elbow brace model is used for path simulation and printing experiments,and the mechanical properties of the brace printed by this method are improved by 3.74 times compared with that before optimization,and the surface quality is also improved,which realizes unsupported rapid 3D printing of the brace.

Key words: brace 3D printing, unsupported, variable layer height, model compensation