Heat Treatment Technology of Tapered Roller Bearing

Time：2020.09.14  Source：Roller Bearings Suppliers

When the material of the tapered roller bearing is determined, the heat treatment technology is the key technology to determine the service life of the bearing. In the past ten years, the conventional heat treatment of bearings has developed rapidly, and the heat treatment of bearings with ordinary precision and general life can fully realize mass production.

For a long time, the heat treatment of high-carbon chromium bearings adopts martensite quenching and low temperature tempering, and the bainite quenching and tempering process is only used in railway passenger cars and some rolling mill bearings.Surface modification mainly includes low-temperature ion permeation, carbonitriding, ion nitriding, surface coating, ion implantation, and laser high-energy beam surface heat treatment. Low-temperature seepage can improve the self-lubrication of the bearing and reduce the friction coefficient of the bearing; carbonitriding, ion nitriding, etc. can increase the surface hardness and increase the wear resistance.

The technical progress in the annealing process of tapered roller bearings is mainly reflected in energy saving and temperature uniformity. Waste heat utilization annealing, double-row double-layer energy-saving annealing furnaces have been adopted in batches in the bearing industry. The annealing quality is obviously improved and the annealing is uniform. At the same time, the energy saving is at least 25% compared with before, and the lowest can reach 110 degrees. 

The annealing power consumption is basically equivalent to that of foreign countries. However, the degree of refinement of the structure after annealing is not fine enough. The refinement and uniformity of carbides have an impact on the service life of the bearing.  WSBC  22230 CCK/W33 bearings online , pls click here :

After forging tapered roller bearings, the single refinement process and the double refinement process have not been applied in industrial batches. It is estimated that a technological breakthrough will be achieved soon. It is reported that the double refinement can increase the life of the bearing at least twice. However, the double refinement process is risky, and the key technology of the process has been broken. Industrial practice is advancing, and the double refinement process will also be promoted in high-end bearings in the near future. The double thinning process can not only increase the life of the bearing, but also improve the dimensional stability of the bearing operation. At the same time, it can give full play to material properties and save material resources.

Bainite quenching results in lower bainite structure with better impact toughness. Compared with martensite, bainite has better impact toughness, fracture toughness and dimensional stability, but the hardness is lower than martensite. High-carbon chromium bearing steel bainite quenching has been successfully applied in railway and other industries, and has achieved good benefits.

The carburizing and carbonitriding processes of high-carbon chromium bearing steel are relatively mature abroad, and some domestic manufacturers have stepped into it. Carburizing and carbonitriding high-carbon chromium bearings are mostly used in high-end cars, high-end motorcycles and precision machine tools. These markets are now mostly occupied by foreign countries, and this market has a bright future. The carburizing and carbonitriding process of high carbon chromium bearing steel can extend the service life of the bearing.Ion implantation technology has been in the bearing surface modification for nearly 20 years. It can improve the friction of the substrate. Wear, corrosion, and other chemical properties are a very meaningful new technology for surface modification of materials.WSBC 22311 CC/W33 bearings online , pls click here :

These surface modification technologies can greatly increase the service life of tapered roller bearings and are worth popularizing in the heat treatment of tapered roller bearings. At the same time, the surface modification technology of high-carbon chromium bearing steel is of great significance to energy saving and consumption reduction. Exerting the potential of materials to the limit is the greatest energy saving and consumption reduction; it is the best way to save resources. Heat treatment technology is the best way to maximize the potential of materials.

The precision heat treatment technology of tapered roller bearings is also developing in a good direction. The precise furnace temperature and controllable cooling medium ensure that the dispersion of the bearing size after quenching is reduced, but the cost is high, which is difficult for ordinary enterprises to achieve. Another type of limited quenching process has been successfully developed in the bearing industry, and the effect of controlling deformation is better. 

Type-limiting quenching is different from die-quenching after carburizing. High-carbon chromium bearing steel is not suitable for die-quenching, and die-quenching is prone to soft spots and unqualified structures; limited-type quenching adopts free quenching in oil above 300℃, 300℃ The following mold limited cooling.

In short, the development direction of the heat treatment technology of tapered roller bearings is to play the material limit, save material resources, and reduce pollution emissions.