Gear hardening heat treatment by high frequency induction hardening machine,what are the commonly used quenching methods?

In order to meet the needs of the work, gears usually need to be quenched and heat treated. Gear quenching is mostly carried out using high-frequency induction quenching equipment, and the effect is very good. Today, we will not talk about the induction quenching process of gears. Let’s talk about the induction quenching methods of gears.

1. Simultaneous heating and quenching

The quenching part of the gear is heated to the quenching temperature at the same time, and the quenching cooling medium is sprayed in place in an instant to quench the heated part. The gear can also be moved out of the inductor and quickly immersed in the quenching tank for quenching and cooling. This quenching method is mostly used for gears with small module (such as m<3mm). The advantages of this method are high productivity, stable quenching quality, and suitable for mass production. If the water spray cooling parameters are adjusted well, self-tempering can be achieved.

2. Continuous induction quenching (i.e. moving quenching, also called scanning quenching)

The gear and the inductor move relative to each other, allowing heating and cooling to proceed continuously until all tooth surfaces are quenched. This method is suitable for situations where the hardening zone is long and the equipment power cannot meet the simultaneous heating requirements. This method is mostly used for gears with large modules (such as m>4mm). Some gears use water as the quenching cooling medium and are prone to quenching cracks after continuous induction quenching. In this regard, the water temperature can be increased to 60°C, the water spray pressure can be 0.05-0.08MPa, and a water curtain sprinkler can be used to form a complete water curtain spray gear surface during cooling.

3. Self-cooling quenching method

After the gear part or surface is rapidly heated and austenitized, the heat in the heated area is conducted to the unheated area by itself, thereby causing the austenitized area to be rapidly cooled and quenched. The application of the self-cooling quenching method requires that the original structure is a quenched and tempered structure, the heating specific power is larger, and the hardenability of the material is better, such as 50Cr steel. This method is mainly used for continuous quenching of single teeth with module m>6mm. The quenching hardened layer obtained by this quenching method generally does not exceed 2mm, which can completely avoid the occurrence of quenching cracks.

4. Submerged liquid quenching

Put the gear in oil or water for induction quenching, which is often used for continuous heating and quenching of single teeth of gears. Heating in water is used for quenching medium carbon steel gears with module m>3mm, and heating and quenching in oil is used for quenching large gears with module m>8mm.

5. Quenching by immersion cooling (quenching by immersion cooling)

For some alloy steel gears, after induction heating is completed, they are immediately immersed in a quenching tank for cooling (the entire gear is cooled in oil or water after induction heating). The immersion cooling time varies with the type of quenching cooling medium. For L- AN15 or L-AN32 total loss system oil, immersion cooling time ≥120s.