What are the common heating methods for induction heating furnace quenching? How to choose?
(1) Due to the different shapes of the heating parts and the different areas of the hardened zone, a variety of suitable processes must be used to operate. In principle, induction heating furnace quenching is divided into two categories: simultaneous heating and quenching will heat the entire hardened zone at the same time. After the heating is stopped, cooling is performed at the same time, and the relative position of the parts and the sensor does not change during the heating process. At the same time, the heating method can be divided into rotating or non-rotating parts in the application, and the cooling method can be divided into two types: falling into a water sprayer or spraying liquid from an inductor. From the perspective of increasing the utilization factor of generators (except for one generator supplying multiple quenching machines), and the heated parts fall into the water sprayer, both the productivity and the generator utilization factor are higher than those of the inductor spraying method.
(2) Scanning quenching in induction heating furnace is often referred to as continuous quenching. This method only heats a part of the area to be quenched at the same time. Through the relative movement between the inductor and the heating part, the heating area is gradually moved to the cooling position. Scanning quenching can also be divided into non-rotating parts (such as machine tool guideway quenching) and rotating (such as cylindrical long shaft). In addition, there are scanning circle quenching, such as the outer contour quenching of a large cam; scanning plane quenching, also belongs to the category of scanning quenching. Scanning hardening is suitable for situations where a large surface area needs to be heated and the power of the power supply is insufficient. A large number of production experience shows that the simultaneous heating method under the same power supply power, the part productivity is higher than the scanning quenching method, and the area of the quenching equipment is correspondingly reduced. For shaft parts with steps, during scanning and quenching, due to the electromagnetic field deviation of the inductor from the large diameter to the small diameter step, there is often a transition zone with insufficient heating, which makes the hardened layer discontinuous over the full length of the shaft. Nowadays, the simultaneous longitudinal current heating method has been widely adopted in China to keep the hardened layer continuous over the full length of the stepped shaft, so that the torsional strength of the shaft is improved.
