2. Scanning Hardening
Scanning hardening is also called continuous hardening. This method is often used for shaft hardening. In this method, the scanner controls the induction coil to move at a constant speed. The induction coil starts at one end of the shaft for surface heating and it slowly moves to the other end of the shaft.
Like simultaneous heating hardening, in the process of scanning hardening, the shaft can also rotate at a constant speed to ensure temperature consistency.
Induction coils are usually equipped with a water spray that will immediately spray the heated area. The water spray will be set to start after 1 second or 2 seconds of heating.
Application of scanning hardening
When the surface hardening area is relatively large and the power of the power supply equipment is insufficient, we usually use scanning hardening.
Common scanning heating induction hardening applications:
- Circumferential scanning hardening of the outer surface of camshaft
- Scanning hardening of track surface
- Scanning hardening of automobile shaft
- Scanning hardening of single tooth of large gear
When the surface hardening area is relatively large and the power of the power supply equipment is insufficient, we usually use scanning hardening. Extensive production experience shows that under the condition of the same power supply, the production efficiency of parts by the simultaneous heating method is higher than that by the scanning hardening method, and the hardening equipment occupies less floor space.
Hardening of stepped shaft parts
During the scanning heating process, the temperature will be low in the transition zone from the large-diameter step to the small-diameter step. This is because the transition zone creates an offset in the electromagnetic field of the inductor, causing a discontinuity in the quenched layer along the entire length of the shaft.
At present, the method of simultaneous heating with longitudinal current is generally used to keep the hardened layer of the stepped shaft continuous throughout the entire length, thereby improving the torsional strength of the shaft.