In general the manufacturing of bearing require strict technological step that are performed on highly specialized equipments that require timely adjustments at batch changes. The process of forging and heat treatment stages consume the most amount of energy but the most expensive stage is the grinding operation. An alternative to grinding and honing processes is hybrid machining by combined hard turning and rolling process. One main development directions of all major roller bearing manufacturers is improving durability of bearings by reducing the roughness by inducing high residual stresses in the surface layers of bearing rings and improving the profile of roller for reduced contact stress. Rolling can induce higher surface stresses and reduce roughness with benefits to the durability of the bearings. The present paper presents and analysis of the technological route for bearing ring and bearing roller and focuses on the research direction on the advances in manufacturing / machining methods for bearing rings and rollers.
In general, the production of bearings is a very large series production, which is why in production the technological lines are designed to process a single size of bearings. Changing the production line for different types of bearings is expensive and time consuming, especially where grinding and honing processes are required. An alternative to these abrasive processes is hard turning. The literature indicates that due to highprecision machines, the accuracy of hard-turned parts is comparable to grinding processes. It is also indicated that the integrity of the surface and the topography of the surface together with the residual induced stresses are parameters of interest and that influence the performance of the bearings. So one method of increasing the durability of the bearings is to ensure a low roughness of the elements and high residual induced stresses. Deep rolling is considered as an alternative to honing and rectification processes. Rolling can induce higher surface stresses in the material compared to honing and grinding. The present paper proposes a combined cutting tool made of a hard turning head and a rolling cutting tool for machining bearing rings. A simulation of this combined process is performed with the help of the finite element and thus the internal stress field, the temperature fieldand the topography of the processed surface aredetermined.
The bearings represent an important element in the mechanical structures, ensuring the proper functioning of the moving / dynamic elements. An important feature of the bearing is its durability, which is necessary for long-term use. This characteristic is influenced by the contact between the rolling element / ring and the rolling elements / balls or rollers. This paper proposes a comparative study of the influences of different types of cylindrical roller profiles proposed in the literature and by the author on the durability characteristic. There are 3 types of profiles, standard, Fujiwara and a profile calculated by the author based on the solid of equal strength.
Maintenance is presented as the totality of some activities that have as objective the maintenance or restoration of an equipment in normal operating parameters. From an economic point of view, for all production costs, it is recommended to plan these costs, taking into account the costs necessary for equipment maintenance activities. The maintenance strategies that the company performs must follow certain standards, taking into account the maintenance policy that guides them and the chosen maintenance methods. Depending on the type of maintenance used in the factories, they can have a positive or negative impact on the company’s economy, caused by certain factors.
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