Potential of lightweight construction and component properties of joined spur gears

Lightweight construction nowadays is a very important issue in the automotive industry. In this paper the approach of a multi-component gear design with high-strength gear rim and stress-related designed of the gear body is investigated based on static and dynamic experiments. The aim was to evaluate if this approach can compete with state-of-the-art gears built in an integrated design, where the gear is produced in one part. The experimental program includes different variants of multi-component gears such as gears with a gear body out of cut and stacked sheet metal as well as a deep-drawn and a cold forged gear body. The evaluation of the experiments showed, that the tested gears could withstand high static torques up to 890 Nm but significantly lower torques in the dynamic test. In the experiments on the static test rig the gears failed mainly by a slipping motion of the gear rim on the gear body. Variants with a form fit type connection between gear rim and gear body showed the highest torques in the dynamic tests, assuming that the gear body has a sufficient material strength. The lightweight potential was determined by relating the load carrying capacity with the component weight of the specimen. The variant with the gear body forged into the gear rim reached the highest lightweight potential of 32 % compared to a reference variant. The multi-component gear design with the actual implementation cannot compete with state-of-the-art gears produced in an integrated design in terms of strength, but appeared to be a promising approach with further potential in load carrying capacity and lightweight potential.