Located in Mellansel, north of Stockholm, Sweden, Hägglunds Drives manufactures heavy-duty hydraulic motors, the largest of which has a maximum torque capacity of 1400 kNm! Producing such motors, of course, places tough demands on the hardening process. A key requirement from Hägglunds Drives,for example, was that the new solution boost throughput, but at the same time assure optimum hardening results. The new solution also had to facilitate supervision of the complete hardening process. The hardening solution designed and installed by EFD Induction operates in a frequency range of 10–25 kHz, and has a maximum output power of 1600 kW. For small cam rings (<700 mm diameter) stationary hardening is used. The system uses scanning for larger rings, the largest of which have a diameter of more than one meter.
The new system has to date resulted in hardening cycle times that are 85% shorter for large rings, and 45% for smaller rings. The system works by first placing the rings on an inlet conveyor. The rings are marked and roughly localized by a vision system. A manipulator then lifts the cam rings into the working station. Each ring is placed on a controlled center and is exactly positioned prior to hardening. The finished rings are then lifted onto the outlet conveyor.