Influence of design on distortion of oil quenched gear base bodies

On the basis of economic and ecological arguments a reduced weight of automobile components are more focused in industrial and scientific activities in recent years. Apart from the application of new materials with considerably lower specific density a change of component design is often used to succeed in aims regarding lightweight construction.

During a designing process the function of the appropriate component is principally paramount. But aspects for a production-orientated design of components have to be considered, too. This applies in particular to the final heat treatment because serious distortion problems could arise due to reduced stiffness of the component. But in the moment no systematic compilation of effects by design modifications on principal distortion behavior exists. For this reason, distortion and its generation of gear base bodies were analyzed based on fundamental experimental investigations and numerical studies. The geometrical variations consists of different size classes (passenger car and utility vehicle with weights of about 1 kg respective 10 kg) and different degrees of symmetry (axial and mirror symmetry, axial symmetry, and periodic symmetry).

In this work experimental investigations of gear base bodies from the smaller size class (starting weight 1.18 kg, largest weight reduction 25%) will be presented. The case hardening was done with gas carburizing and oil quenching (Results of IDE 2015: low pressure carburizing and high pressure gas quenching). The effects of the reduction of degree of symmetry on size and shape changes will be presented and discussed as far as possible.