Feature Islands and Identification Method of Laser Deposition Manufacturing

Laser deposition manufacturing (LDM) technology has unique advantages in additive manufacturing of large aircraft frames and beams. However, stress and deformation have become bottlenecks that hinder the application of this technology. Therefore, the islands process is widely used to discrete the residual stress and alleviate the deformation of the parts. However, the traditional islands process does not take into account the geometric structural features of parts, easily leading to irregular partition lap, which introduces pores, poor fusion and other defects. In order to solve this problem, a feature islands method was proposed. According to the geometric shape characteristics of the slicing layers of typical frame and beam structural parts, the features were classified into four types: "+"-shape, T-shape, L-shape and "-"-shape features, and all kinds of features were limited from three aspects: shape, pose and size, to complete the definition of island features. A feature recognition algorithm based on region skeleton line detection was proposed, where the skeletonization was used to effectively simplify the features and retain the part characteristics. The vector cross-product and fixed-ratio point method were used to calculate the relevant parameters such as feature angle, plane attitude angle and number of feature branches. Feature type identification was achieved by comparing calculated values with defined values. The algorithm was verified by slice data of a typical aircraft frame model. The results show that the algorithm can quickly and accurately identify various features to realize automatic feature islands of parts, which lays a foundation for intelligent additive manufacturing technology.