Tribological operational behaviour of eroded rolling contacts

Highly loaded rolling contacts, such as the tooth flank contact, are complex tribological systems whose properties are determined by the interactions between the contact partners, the lubricant and the surrounding medium. The friction results from the state of lubrication in the contact, which depends on the lubricant, the temperature as well as the surface roughness and structure. In order to reduce friction and increase the load carrying capacity of highly loaded rolling contacts, recent research has focused in particular on surface topography as an optimization parameter. For deterministically generated surface structures, flat cup structures show an improved friction behaviour compared to polished surfaces. Spark erosion can generate such a surface structure by the process-inherent formation of a crater landscape. In preliminary investigations it could be found out that during wire erosion tribologically favourable surface structures can be adjusted by means of suitable post-cuts.

Using a modern process, the load carrying capacity test tripled the tolerable number of load cycles in the fatigue strength area for the pitting load carrying capacity of wire-cut gears compared to ground gears. The objective of the project is the development of a knowledge-based process model for the relationship between the parameters of spark erosion and the resulting surface integrity of the machined component. On the basis of physical parameters of the discharge regime, a description model is developed, which forms the basis for the optimization of spark erosive edge zones and surface structures. Based on this, the aim is to investigate the tribological application behaviour experimentally in a two-disk analogy test and to extend the existing rolling strength calculation to the tribological contact of stochastic surface structures.