Papers by Author: Yu Sheng Shi

Abstract: Based on the structured light measurement principle, digital fringes projection technology and phase-shifting measuring technology, specific to the 3D profile of some tiny objects like teeth, in this paper we proposes a 3D scanning system which was directly used for intraoral dental measurement utilizing the merits of flexible and long distance signal transmission of the fiber image bundle. The structured light is projected out from DLP LightCommander produced by Texas Instruments Company, shrunk via telecentric imaging lens, conveyed in fiber image bundle. Utilizing the transformational relation between single-camera and projector, afterwards, the 3D profile of teeth is obtained by reconstructing the acquisition images in electronic endoscope. The feasibility of this system has been testified in our experiments. It satisfies the requirements of miniaturization, directness and flexibility; expands the scope of application of micro-3D measurement with structured light in dental clinical practice.

Abstract: Selective Laser Melting (SLM) technology can be used to fabricate plastic mould with complex conformal cooling channels directly and rapidly. In this paper, 316L stainless steel powders were used to produced a mould with an emphasis on attaining excellent mechanical properties.The precision, density and mechanical properties of parts were studied. Simulation and experimental results showed: the mould manufactured by SLM reveals good accuracy and performance, and the cooling efficiency of conformal cooling channels in mould has been greatly improved and the uniformity of cooling has been also upgraded.

Abstract: Selective laser melting(SLM) is driven by the need to fabricate functional metallic parts and tools with near shape and density. The method of process to fabricate a metal part will save materials, time and energy compared to the traditional manufacturing methods. Unlike the selective laser sintering (SLS), the metal powder particles are molten by the laser beam during the process of selective laser melting. In this paper, IN625 powders were adopted to investigate the characters of single molten track. The factors that affect the surface quality and relative density are the process parameters such as the laser energy, scan speed and so on. They were studied to find out the correlation between the parameters and formation of single-track. It has been found that Optimal ratio between laser power and scanning speed (P/v) is 1-1.5 for IN625 SLM. P/v is the linear energy density. It also has been found that the width and height of single-track can be calculated when the linear energy density is given. In this study the laser power, scan spacing and the hatch spacing which affect the surface quality and the relative density of the metallic parts were optimized.