Heat Treatment Systems for Cast Wheels
This furnace type is built specifically for solution annealing, quenching and artificial ageing of cast aluminium wheels. Energy efficiency, maintenance-friendliness and flexibility were particularly important considerations in developing its design.
The wheels are conveyed through the entire line without racks, using a multi-tier walking beam system.
The furnace is operated in mixed mode, i.e. the wheel diameter may vary between 14“ and 24“ between any two wheels. Heating is effected directly using natural gas burners in the furnace chamber. Thanks to an optimized combustion process and the use of recuperative burners in the first zones, this configuration provides an unsurpassed energy efficiency.
Contrary to conventional systems relying on annealing racks, the system has been designed without racks in order to save energy. The parts to be heat-treated are fed into the furnace via a roller table on which they are also aligned, measured and positioned. Once the complete charge has been assembled, it is placed in the furnace by the loading manipulator.
The charge is moved through the furnace by a walking-beam system. This is a further development of the walking beam conveyor used in steel heat-treatment applications which are noted for their particularly exacting demands regarding ruggedness and reliability of the conveyor system (refer to the description below). The charge is moved at low speed, making full use of the cycle time, to prevent damage to the product in its contact area.
At the exit of the walking beam furnace, the wheels are removed by a manipulator which immerses them into the quench tank. From here the parts are conveyed into the artificial ageing furnace for completion of the heat treatment.
At the end of the artificial ageing cycle the wheels are picked up by a manipulator which places them on the exit roller table. From here they are moved to a cooling station for cooling with cold air.
The entire system is controlled by a PLC which monitors all motion sequences, temperatures and motor functions. A PC with visualization software monitors all operating parameters and stores all equipment operating data.
High energy efficiency due to the following features:
- no use of annealing racks ("dead weight“) to be heated with the charge
- no need for wall openings due to the specific conveyor design
- very maintenance-friendly design, since all components are externally accessible
- very compact footprint (in line or U-shaped configuration)
Particular equipment characteristics:
Description of the conveyor motion sequence inside the furnace:
All movements are performed very slowly to prevent vibrations and consequential damage or surface marks on the wheels.
Phase 1 – Lifting
The mobile inner frame is raised with all wheels, thus lifting the wheels off the stationary frame.
Phase 2 - Advancing
The inner frame is moved forward in accordance with the preset advance step. The advance step depends on the maximum product dimensions.
Phase 3 - Lowering
The inner frame is lowered, thus placing the wheels back on the stationary frame.
Phase 4 - Return
The inner frame moves away from under the wheels and returns to its home position for the start of the new cycle.