Studies On Splicing Composite Forming Process Of Selective Laser Melting

Selective Laser Melting is one of the most potential addictive manufacturing technologies.By using a high-energy laser beam to melt metal powder directly, it can manufacture nearly full density metal parts. This technology can manufacture complex structures which are impossible for traditional methods, so it has a broad application prospect in fields such as aerospace manufacturing, personalized bio-manufacturing and complex mold inserts manufacturing. But there exist some problems such as accurate manufacture and high cost for parts by SLM. Parts consist of high accuracy and personalized complex structures are hard to manufacture from single traditional or SLM manufacturing methods. This paper is to combine traditional method with SLM method, through manufacturing complex parts on the base of accurate parts made from traditional way.Firstly, the paper makes a basic technical route, does a pre-experiment and proposes experimental programs. Then the paper makes positioning scheme among the placed part,CAD model and substrate, controlling the targeting positional error rates among them.Then the paper does a temperature field simulation for the formation upon the placed part.Keeping equal energy input density, the simulation set different laser powers and scanning speeds to explore influences on single line's formation and melting pool temperature's transfer.Optimized blocked surface flux input reduce the sticky powders around formation area and it explores the temperature transfer of surface formation.After the simulation upon, the paper makes experiments solve the problems of single lines discontinuous and splashing with balling, surface formation with serious balling and small cracks by keeping equal energy input. Obtained good laser power and scanning speed makes stable single lines and smooth surface performance.Finally, the paper makes full splicing formation with suitable laser power and scan speed.The microstructure analysis shows good metallurgical bonding between initial melting pool and substrate matrix. Adding remelting volume improves the number of meting pools with substrate matrix and improving the bonding strength. The vickers hardness shows HVdecrease from SLM forming surface upon to matrix because the melting layer's heat transfer to the layers below which is likely to do a heat treatment to the layers making the hardness lower. The tensile experiments show that energy input rate makes a significant effect on the specimen's tensile strength.