Study On Laser Remanufacturing And Performance Improvement Method Of Gear Parts

Remanufacturing can make waste products which contain value develop and utilize, reduce the environment pollution of scrap products, and prolong the service life of the parts. Remanufacturing engineering is one of the key parts of circular economy development and economical society establishment, and it is significant to economy and society. As one of the advanced remanufacturing technologies, laser cladding technology has lots of merits which supply apparent dominance for equipment parts repairing and remanufacturing, such as weak substrate impairment, high processing accuracy and so on.Gear failure will directly affect the normal operation of the mechanical system as it is the major part for load and movement transmission. The repair rate of gear part is very low due to the limitation of traditional maintenance method. With the development of laser technology, the new repaired gear part method is provided. In this paper, the damaged gear parts were investigated. Remanufacturing of gear parts was operated by laser technology, and then active screen plasma nitriding duplex treatment was processed to improve the performance of gear parts. The principal results are as follows:Research on laser rapid forming is carried out to settle the problem of hardened and tempered steel gear repair. Microstructure and mechanical property of laser rapid forming sample were researched, and the influence of repair ratio to the performance of laser remanufacturing parts was discussed. The results showed that the microstructure of laser rapid forming sample is dense with a characteristic of rapid solidification, and the sample has high mechanical properties. The performance of repaired specimen depends on laser repair zone and substrate, and the strength of repaired sample increases and the plasticity reduces with the increase of the ratio of laser repaired zone.Crack formation mechanism and control measures of laser cladding coating were discussed for laser repair the wear surface of cast gear, and a new method of brush electro-plating and laser cladding duplex treatment was presented to reduce the cast iron laser cladding crack sensitivity. The results show that the duplex treated coating is dense, without any metallurgical defects such as crack and porosity. It provides a feasible technology way for cast iron gear parts remanufacturing.The medium manganese Fe-based alloy with low price, well formability and self-strengthening properties was designed to repair surface damage of high speed over-load carburizing gear. The microstructure of medium manganese Fe-based alloy laser cladding coating is dense, and the coating and the substrate is metallurgical bond. The cladding coating has good property of hardness, wear resistance and contact fatigue resistance. Research on self-strengthening mechanism of laser cladding coating was carried based on thermodynamics calculation, valence electron theory and impact abrasive wear methods, and the result provides theoretical support for industrial application.The method of remanufacturing gear part property improving by laser cladding and active screen plasma nitriding duplex treatment was studied and the design principle of laser cladding and active screen plasma nitriding duplex treated coating was discussed. Results show that the surface hardness, corrosion resistance, wear resistance and contact fatigue property of laser cladding were improved apparently after duplex treatment. Reasonable collocation between laser cladding coating and load is the key for performance improvement of laser cladding and active screen plasma duplex treated coating. The basic design principle of duplex treated coating is that laser cladding can provide enough support to protect nitride layer from destroying.