Novel approach in cold forging for efficient manufacturing of shaft-hub-assemblies

Today, electric mobility, weight of vehicles and costs of powertrain components continue to play an essential role. Therefore, material consumption and the type of production have a significant influence. Gears have an essential significance in mobile powertrains. In the past few years, recent developments have shown the technological potential of shaft-hub connections produced by joining by forming. In order to improve manufacturing time and costs while saving material waste, a representative two-piece design consisting of a gear ring and a gearwheelbody offers a wide variety of possibilities for individual design of the shaft-hub connection and a suitable material combination. Therefore, two process strategies have been investigated at the Institute for Metal Forming Technology in Stuttgart. First, a shaft is joined with a hub by lateral extrusion. For the second manufacturing process, a blank is placed between a gear ring and a shaft and is joined by cold forming. In order to manufacture two-piece shaft-hub-connections, a gear ring needs to be produced prior to joining. Thus, a new cold forming process has been developed to enhance the economic efficiency and material usage for manufacturing of radial gears. In this context, gear rings offering the required tolerances can be produced for the described joining process without additional machining. In this process, a sequential forming of the tooth geometry is performed, which results into a reduction of the forming force and tool load. This contribution describes the combination of both processes in order. The novel manufacturing method for an exemplary gearwheel is presented and the required forming process steps are numerically examined considering their applicability.