Studies on the Influence of Residual Stresses on the Fatigue Life of Rolling Bearings in Dependence on the Production Processes

Abstract

The production process significantly influences the surface properties of rolling element bearings raceways. Deep rolling can induce a depth dependent residual stress state. Previous numerical and experimental studies have shown that rolling bearings fatigue life can be positively influenced by high compressive residual stress to a depth of around 300 µm from the surface. By extending the components life, the resource efficiency of machine components can be increased. In order to determine the influence of the residual stress state in bearing fatigue life, a calculation method was developed for predicting the bearing fatigue life. This method was validated for hard-turning and subsequent deep rolling by experiments on a test rig in four-bearing configuration under radial load. An increase of the L 10 bearing life by a factor of 2.5 has been achieved by inducing residual stresses on the bearing's inner ring. Due to similar process control, the manufacturing steps turning and deep rolling were combined. Bearings were manufactured combining the processes hard-turning and deep rolling (called turn-rolling). The heat from the hard machining has an effect on the residual stresses in the bearing subsurface, thus further altering the magnitude and maximum depth of the residual stress influencing the microstructure. With these bearings, the additional fatigue life was determined experimentally and compared to the results of the bearings produced by hard-turning and subsequent deep rolling. It could be shown, that the process of hard turning and subsequent deep rolling has highest potential to achieve improved bearing fatigue life. These findings were transferred to a "Tailored Forming" shaft with integrated raceway in a second step. In this case, a shaft made of mild steel is combined with a cladding layer of high strength bearing steel to be used as a bearing raceway.

Production-Related Surface and Subsurface Properties and Fatigue Life of Hybrid Roller Bearing Components

“…As expected, the density function shows negative skew. For the roller bearing life of SAE52100 bearing steel under good lubrication conditions (κ ≥ 2), the size of the Weibull exponent ranges from β = 1 to 1.5 [28,37]. According to Reference [17], a general shape parameter of β = 1.35 for roller bearings is known, which shows that the conventional reference tests correspond well to the expected values, leading to rolling-contact fatigue.…”

“…Additionally, an FEM-based model, in combination with a calculation routine, was set up to compute the influence of residual stresses on bearing fatigue [25,26]. However, current research results show that too-high residual compressive stresses can also lead to a shorter service life [27,28]. A cause for this is not yet known and currently represents a research gap [29].…”

Targeted adjustment of residual stresses in hot-formed components by means of process design based on finite element simulation

“…On the one hand, fatigue cracks were found in some investigations not only on the surface but also underneath the surface, for example, in roller bearing rings [51]. It is therefore necessary to investigate which distribution of compressive residual stresses in the depth profile provides the most effective increase in fatigue strength.…”

Investigations on Tailored Forming of AISI 52100 as Rolling Bearing Raceway

“…At the location of direction change in the course of the welding track, early fatigue cracks were initiated due to the higher heat input and the local microstructure evolution. The positive influence of compressive residual stresses on the fatigue life of radial bearings made of AISI 52100 was investigated in [10]. In contrast to the aforementioned, tests were carried out on real components under a high Hertzian contact pressure of 2.5 GPa.…”