Deformation analysis of truck gears before and after control hardenability strip steel

Three typical parts of heavy truck gearbox hc7s-120: first and second speed gear sleeve (representative of thin-walled castings), fourth speed gear (representative of transmission gear), and second shaft (representative of shaft parts). Carburizing and quenching process test of steel with guaranteed hardenability is carried out and its deformation law is analyzed. The following conclusions are drawn:

(1) Heavy truck gears are made of steel with guaranteed hardenability band. Due to its narrow hardenability band and relatively uniform microstructure after carburizing and quenching, the deformation dispersion of parts after carburizing and quenching is small and all kinds of dimensional data are relatively uniform. Under the same carburizing and quenching conditions, the deformation of parts is more regular than that of ordinary carburized steel, which has also been proved in our process test. The first and second speed gear sleeve parts represented by thin-walled parts are made of steel with guaranteed hardenability. Under the same pressure quenching conditions after carburizing, the variation of m value of gear sleeve spline span rod distance is 0.04mm on average, and the ovality of outer circle is also small, generally less than 0.04mm, which is smaller than that of ordinary steel; Transmission gears represent four speed gear parts, which are made of steel with guaranteed hardenability. The m-value variation of truck gears is less than 0.03mm on average, while the m-value variation of ordinary steel truck gears is generally 0.02 ~ 0.06mm after heating, and the variation is larger.

(2) The gear parts of heavy-duty trucks should be made of steel with guaranteed hardenability, so as to lay a good foundation for controlling the carburization and quenching deformation of truck gears, and then ensure the mass production of truck gear parts.

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