Study On High Pressure Pump Camshaft Laser Cladding High Hardness Wear-Resistant Coating Process

At present, conventional high-pressure fuel injection pump camshaft is usually made of low-carbon steel(20Cr Mn Ti / Mo) by carburizing and quenching manufacturing process. But But with the engine power increased, further reduced volume, fuel injection pump camshaft working pressure is gradually increasing. In a short service period, the contact surface of camshaft and roller are prone to excessive wear and fatigue pitting or spalling phenomenon, affecting the normal work of the fuel injection pump. In this paper, using high-power CO2 lasers, four axis CNC machine tools and automatic powder feeding device study preparation of the high-pressure pump camshaft high hardness and wear gradient coating process by laser cladding process. The main contents of this paper are as follows:(1) Designed a gradient coating process programs, and optimize laser cladding process parameters of graded layers by orthogonal test. after each layer gradient optimization of process parameters(laser power, scanning speed, the amount of powder feed), respectively to: bottom 1800 W, 280 mm / min, 0.6r / min. Interlayer 280 mm / min, 0.7r / min. Wear layer 2100 W, 280 mm / min, 0.6r / min.(2) A camshaft laser cladding trajectory control method, and the corresponding mathematical models. With this control method to complete the preparation of gradient cladding layer, the test results show that the laser cladding layer thickness uniformity, no cracks, holes produced.(3) using optical microscopy, scanning electron microscopy, X-ray diffraction, micro hardness tester for laser cladding layer microscopic analysis showed that: the cladding layer and the substrate to achieve a good metallurgical bonding, forming a distinct junction "white band "; gradient cladding layer is mainly composed of γ-Co,(Ni, Fe) solid solution, Co CX, Cr7C3, M23C6 and other phases; gradient coating microhardness performance from the surface to the substrate is continuously decreased, but not good transition showing a significant step-like. The average microhardness of the entire wear layer of 690 HV, the matrix hardness of about 3 times. 0.6mm deep within the surface hardness are 720HV(HRC61) above, the hardness of the cladding layer can meet the performance requirements of the cam surface.