Research And Implementation Of Scanning Path Generation Method To Guarantee The Quality And Stability Of Additive Manufacturing

Despite the potential benefits of additive manufacturing over traditional subtractive manufacturing,there are still several intrinsic problems that affect the accuracy and quality of the additive manufactured parts adversely.One of which is the undercut problem,and the allowance for machining cannot be guaranteed on the surface of the additive manufactured part,according to existing slicing methods.Therefore,the accuracy of the post-processed parts cannot be guaranteed as post-processing is generally a process of subtractive manufacturing.Another problem is the warpage and deformation of additive manufactured parts,caused by residual stress due to large temperature gradient while the metal powders are scanned with high energy beam and a metal part is manufactured with the powder bed type additive manufacturing technology,ultimately the dimensional accuracy and the strength of the formed metal part is affected.In this thesis,in order to improve the quality and stability of the additive manufactured parts,a slicing algorithm is proposed to prevent the undercut problem absolutely and guarantee non-negative error of the additive manufactured part.Meanwhile,a new type of scanning path is proposed to reduce the warpage and the directionality of the strength,and improve the strength of the part.The main contents of this thesis are as follows:(1)A slicing algorithm is proposed to guarantee non-negative error of additive manufactured parts.Not only the input model is simply intersected with a group of parallel slicing planes to get layer contours,but also the local geometry between two adjacent slicing planes is integrated into the layer contours.Therefore,each sliced layer of the model is fully contained inside the volumetric geometry constructed by extruding the bottom contours of each layer for a layer thickness along the building direction.(2)A honeycomb scanning strategy is proposed for additive manufacturing.With this strategy,the area to be scanned in each layer is partitioned into a serial of hexagonal regions.The regions do not overlap and connect with each other.The regions and the intervals between the neighboring regions in a layer are scanned separately.(3)A variety of scanning methods based on the honeycomb partition are designed and implemented.