Feasibility study and thermal process of producing deep-small holes by laser/ultra-high frequency induction hybrid deposition

In this study, a laser/ UHF induction hybrid deposition process with embedding tube for forming deep-small hole method is proposed. The laser and induction powers, as main and auxiliary heat source, are used to melt the metal wire and preheat the objects (the substrate, metal wire and embedded tube), respectively. The critical role of the preheating is to provide a high-temperature zone on the objects which guarantee the effective bonding among the deposited track, substrate and embedded tube. The embedded tube is pre-placed on the substrate outside induction coil and is not irradiated by laser beam, but is wrapped in the deposited track by dripped molten droplet. A numerical model coupled with temperature and electromagnetic fields is developed to investigate the thermal process during hybrid deposition. The thermal process with different combination states of laser and induction heating is numerically investigated to reveal the influence mechanism of the two heat sources on the penetration deposition of the deposited track and the size of molten metal in front of the deposition track. Results show that the laser heat mainly dominates the penetration depth of the deposited track and the size of the molten metal by increasing the temperature of the deposited metal. Criteria for characteristic temperature Tpeak2 is proposed based on the thermal process to avoid excessive temperature and possessing a large penetration depth of deposited track. The experiments demonstrate the process feasibility of the proposed deposited method and verify the reliability of the numerical model.