Investigations Of Mental Rapid Manufacturing By Laminar Plasma Torch

Due to DC plasma torch has high energy density, it is widely used in the field of material preparation, surface heat treatment, and solid waste treatment etc.. Compared with the laser and electron beam, DC plasma torch has advantages in the field of metal rapid manufacturing (MRM). It has faster manufacturing efficiency, lower manufacturing cost and higher efficiency of energy utilization. The laminar plasma torch possesses long jet, good collimation, concentrated energy, so it can greatly improve the quality and efficiency of MRM.In this paper, for the MRM realization, we research about the structure of laminar plasma torch aiming to the MRM by plasma torch.Through the optimization of DC plasma torch structure, the length of laminar plasma jet is18centimeter at the current of80A, air flow of300L/H, the power of3.6KW by argon discharge. And it can run stably for long time.We studied the change of DC plasma torch current, voltage, the outlet temperature and jet length, and the effect of current and air flow on the voltage, thermal efficiency, enthalpy, jet length of the plasma torch. When the current of DC plasma torch is increased, the voltage, enthalpy, and jet length of the DC plasma torch rise, while the thermal efficiency decreases. It is found that the voltage and thermal efficiency of torch increase with increasing the air flow, but the enthalpy drop. This change is due to the pneumatic processes of DC plasma torch and the movement of anode arc toot. We investigated the electron temperature of plasma by optical emission spectroscopy, which can reach12000K.We also research on MRM by the laminar plasma troch. The quality of manufacturing part is significantly affected by the output power of plasma torch, wire feeding speed, platform moving speed. If the power, the speed of wire feeding and platform moving is not appropriate, MRM can’t be completed efficiently. We have fabricated the Cu pipe with0.6cm of tube wall based don by plasma MRM, which is height of3cm and width of2.8cm. It is found that there exits crack in layer with a thickness of the several microns in the cross-section of component, this is caused by thermal stress. We find Cu2+1O in the cross-section based on the investigation of scanning electron microscopy and X-ray diffraction. That is considered that during MRM process, the air is caught in the jet that can generate oxidation。...