JFE Steel Develops Light-weight, High-strength Frame for Small EV

Mar 19, 2010 15:09 Tsunenori Tomioka, Nikkei Monozukuri

JFE Steel Corp developed a light-weight, high-strength steel frame for small electric supply cars in collaboration with Keio University.

Each supply car comes with a battery, motor, tires and other parts needed for moving, and a cabin or container can be mounted on it. The new frame uses a plate made by laser-welding steel plates with different thicknesses. The main material of the plate is a high-tensile steel plate with a tensility of about 1,470MPa. It was designed and manufactured by using computer simulation.

The electric vehicle to which the new frame is applied autonomously moves around indoors and outdoors. As the base of the vehicle, the frame supports the cabin and contains a battery, inverter, in-wheel motor, suspension and steering system.

Therefore, the frame needs to have (1) rigidity for safety, (2) strength for going over steps and withstanding crashes, (3) lightness to be able to travel a long distance and move swiftly and (4) mass productivity.

The high rigidity and lightness were achieved by using a quadrangular closed-section structure for the main frame supporting the vehicle body (the rigidity was increased by seven times and the mass was reduced by 16%). The high strength was realized by employing high-tensile cold-rolled steel plates including a cold-rolled steel plate with a tensility of about 1,470MPa for the frame.

Furthermore, the high productivity was achieved by simultaneously folding multiple laser-welded plates made by integrating the steel plates supporting the vehicle body and the outer plates.

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