Research On Key Technology Of Powder Plasma Spray Welding (PPW) Equipment

Powder Plasma Spray Welding(PPW)technology was a type of welding technology,which transferred arc as heat source and alloy powder as spray welding materials. As a branch of welding technology,it played an increasingly important role in improving the surface properties of materials and prolonging life of machine,which because it had characters of low base metal diluting, solder layer neat, process stability and ease of automation, etc.Firstly,the principle of plasma spray was presented, followed by two parts of the plasma spray welding equipment,the powder feeding system and the structure of the spray gun were made a improved design and analysis. In the part of powder feeding system, it used a carrying gas wheeled powder feeder to feed powder quantitatively, and sent powder to the gun through the way of pneumatic conveying with the combination of the air stream injection and the vacuum. It solved the problem of the alloy powder was difficult to transport because of large proportion, and ensured the stability of powder-feeding. In order to verify the feasibility of powder feeding system, it selected Co50 powder, superfine WC composite powder and Al2O3-Cr2O3 powder to make feeding experiments,which obtained the desired results, and analyzed the effects of the wheel speed, air flow and the size of vacuum suction device to the powder feeding rate. In the design part of welding gun, the mode of blowing port and the structure of water cooling has been improved, and the way of upper and lower separating cooled has been used. After the nozzle’s temperature was analyzed. The nozzle was a key component of the welding gun, and was also a wearing part, which made by C15760 copper, a material having high temperature, high strength and good thermal stability. It used the ANSYS12.0 to make a finite element thermal analysis of nozzle for easy burning, and simulated the heat dissipation of the nozzle in the working conditions, which got the temperature distribution picture. Finally, it compared the effects to the heat dissipation of the nozzle in the different rates of the cooling water, and obtained the optimum velocity. Finally, improvements from the nozzle structure and materials, which could enhance the thermal performance and prolong life of the nozzle.