A brief analysis of the process of quenching and tempering heavy gears using high-frequency induction heating machine

For heavy-duty gears, the most prominent features of this type of gears are large size, heavy weight, low running speed, large tooth root strength margin, and strong impact resistance. During the heat treatment process using a high-frequency induction heating machine, Quenching and tempering is generally used as the final heat treatment. This type of gear is easier to design and manufacture, and is easy to run in during operation. In heavy-duty gear transmission, tempered gears occupy a large proportion. Common ones include construction tower cranes, steering gears of automobile cranes, etc.

The manufacturing process of heavy gears is generally: forging billet (or cast steel billet) - rough machining - tempering - finishing.

Heavy gears are often made from cast steel, so the chemical composition of the gear blanks, especially the carbon content of the cast steel materials, fluctuates greatly. ZG 310-570 (old brand ZG 45) only stipulates a maximum carbon content of 0.50% (mass fraction, the same below). The carbon content of 45° steel is 0.42% to 0.50%, which is strictly controlled by special steel mills. In actual casting, when the upper and lower limits are exceeded, a large gear blank has been cast. It is impossible to cause the carbon content to exceed slightly. Abandoned.

Heavy gears are often made from cast steel, so the chemical composition of the gear blanks, especially the carbon content of the cast steel materials, fluctuates greatly. ZG 310-570 (old brand ZG 45) only stipulates a maximum carbon content of 0.50% (mass fraction, the same below). The carbon content of 45° steel is 0.42% to 0.50%, which is strictly controlled by special steel mills. In actual casting, the upper and lower limits may exceed the tolerance. Since a large gear blank has been cast, it cannot be judged because the carbon content exceeds for scrap.