Steel ball special for large-sized offshore wind turbine generator bearing and manufacturing process of steel ball

Abstract

The invention relates to a steel ball special for a bearing of a large-scale offshore wind power generator group and a manufacturing process for the steel ball. The circularity of the steel ball is 0.4 to 0.8 mu m, the hardness of the steel ball is 59 to 64 HRC, the single-grain hardness grain difference is 0.8 HRC, the batch hardness difference of the steel ball is 1.2 HRC, the core part hardness of the steel ball is greater than 54 HRC, the retained austenite of the steel ball accounts for 8 to 13 percent, the metallographic structure of the steel ball is of 2 to 3 level, the surface roughness of the steel ball is greater than 0.8 mu m, and the crushing load and the compression ratio of the steel ball are 1.2 times greater than a national standard. By combining a plurality of types of technologies of selecting raw materials, adopting hot extrusion continuous molding during ball blank molding, performing multistage quenching by adopting a water-soluble quenching agent during heat treatment, increasing a secondary stable tempering technology and increasing eddy flow nondestructive flaw detection during a process flow and the like, the steel ball has the characteristics of high contact fatigue strength, high abrasion resistance, high elastic limit, appropriate hardness, high impact ductility, high dimensional stability and the like.

Description

technical field [0001] The present invention relates to a special steel ball for a large-scale offshore wind turbine bearing, and also relates to a manufacturing process for realizing the above-mentioned special steel ball for a large-scale offshore wind turbine bearing. Background technique [0002] Due to its environmental protection, wind power generation has been highly valued by various countries in the world in recent years, and the situation of wind power industry has developed quite rapidly. my country's wind power market needs about 30 million special steel balls for wind power bearings, and the international market needs about 1.5 billion. Therefore, special steel balls for wind power generation have broad market prospects. Steel ball bearings on wind turbines generally include: yaw bearings, pitch bearings, and generator bearings. For example, the horizontal axis wind turbine must yaw to achieve facing the wind. The yaw bearing is an important part of the yaw sy...

AI Technical Summary

Problems solved by technology

The raw material is ordinary GCr15 bearing steel, which has poor material quality, high oxygen content, many inclusions, and the service life of the steel is low

[0007] 2. The current international advanced small ring belt cone drum type automatic forming cold heading new technology, although it has solved the technical problem of the surface metamorphic layer in the large-reserve grinding and large-feed grinding; The diameter of the ball is large, basically more than 36mm. Due to the excessive stamping force in the cold heading process, the ball blank cannot be formed normally. Obviously, the cold heading forming technology cannot be adapted; Steel balls with hot rolling technology have the disadvantages of immature tooling and mold technology, high and deep defects on the surface of steel balls, especially the serious sparse phenomenon at the two poles of steel balls, which will form fatigue-prone failure zones during the use of steel balls , at the same time, the steel ball retains a high amount of grinding, resulting in an increase in the cost of materials and subsequent processes

[0008] 3. The heat treatment process is still the traditional processing method, and oil or water is still used in the quenching medium, but the use of oil as the medium will cause insufficient hardenability of wind power steel balls (diameter greater than 36MM), but pure use of water will easily cause steel balls surface crack

[0009] 4. Without secondary stable tempering, it is easy to form steel balls with high residual austenite and poor dimensional stability. During long-term use, the diameter of steel balls will change, resulting in early fatigue of steel balls

[0010] Therefore, there is no special steel ball for wind energy equipment and its process that can fully meet the standards on the market.