Thermal treatment method for reducing secondary gear ring nitrogenized deformation

Abstract

The invention provides a thermal treatment method for reducing secondary gear ring nitrogenized deformation. The method comprises the following steps: (a) tempering after a secondary gear ring is roughly processed; (b) tempering; (c) processing by a gear milling machine, and destressing at high temperature; (d) processing by a gear grinding machine, and performing gas nitrogenization, wherein the gas nitrogenization comprises the following steps: uniformly fixing and supporting a plurality of cylindrical clamps in a gear ring groove; flushing a gear ring in a bell type gas nitrogenation oven, heating, and introducing 8-12m<3> / h nitrogen for 3-5 hours; heating to 400-500 DEG C, introducing 4-8m<3> / h ammonia, and insulating for 0.2-0.8 hours; heating to 500-550 DEG C, controlling the flow rate of ammonia to be 10-15m<3>, and penetrating for 60-65 hours, wherein Kn is 6; turning to diffuse, controlling the flow rate of ammonia at 4-6m<3> / h, and diffusing for 30-32 hours, wherein Kn is 2; cooling along with the oven, introducing 8-12m<3> / h nitrogen while cooling; moving the heating mantle when the temperature is reduced to 400-500 DEG C; discharging parts from the oven when the temperature is reduced to lower than 90 DEG C. The thermal treatment method has the characteristics that the deformation is small, a high-hardness high-wearing nitride layer can be obtained on the surface, the contact fatigue strength can be improved, the drawing performance and accurate requirement can be fulfilled, the product quality can be improved, and the like.

Description

technical field [0001] The invention relates to a heat treatment method for reducing the deformation of a large-diameter thin-walled ring gear, and belongs to the technical field of metal material heat treatment technology. Background technique [0002] Wind power gearbox ring gears are generally straight teeth, with a symmetrical structure, and the material is 31CrMoV9. The heat treatment process includes quenching and tempering, high temperature stress relief, and gas nitriding treatment. Due to the consistent shape and structure of the ring gear parts, the deformation is regular and small during the whole heat treatment process, which meets the accuracy requirements of the drawings. Sorbitite structure, the surface obtains a high hardness and high wear-resistant nitride layer, so that the core of the ring gear obtains high strength and good plastic toughness, has good comprehensive mechanical properties, and the surface has high hardness and wear resistance Abrasion resi...

AI Technical Summary

Problems solved by technology

However, the structure of the second-stage ring gear of the new wind power transmission has undergone major changes, see figure 1 , its structure is inconsistent and symmetrical, and it is easy to deform during heat treatment, resulting in taper and end face warping, which cannot meet the accuracy requirements of drawings and affect product quality

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