| KEYWORD |
Optimization of the heat treatment of roller bearing rings for railway applications
Thesis in external company
Reference persons PAOLO MATTEIS, RAFFAELLA SESANA
External reference persons Ing. Donato Pazienza, ICSA Industria Cuscinetti S.p.A., San Benigno Canavese (TO)
Description The components of the roller bearings, made of 100Cr6 steel or similar, are normally subjected to quenching and tempering, with low temperature tempering, to obtain the mechanical properties that are required in service. This treatment, unfortunately, involves the risk of significant distortions, which must be corrected by grinding (in fact, it is not possible to carry out other types of processing after the heat treatment, due to the high hardness); a particularly important case is the ovalization of the bearing rings, the correction of which may require grinding operations with particularly high material removal (up to 1 mm).
In the thesis work, a plant for the quenching of rings of large bearings (up to 400 mm in diameter), especially for railway use, will be examined, and in particular the effectiveness of different strategies for the reduction of quenching deformations and stresses will be evaluated, including the use of step quenching (i.e. rapid cooling up to a temperature slightly higher than martensite start, followed by a pause and then cooling down to room temperature) and special tools to prevent deformations, with the ultimate aim to reduce the grinding steps required after the heat treatment.
The results obtained will be verified both from a dimensional point of view and from a metallurgical point of view, and will be punctually correlated with the process parameters adopted. Almost all the experimental activities will take place at the ICSA plant in San Benigno Canavese (Via Giotto, 4). Some further characterization activities could take place in the laboratories of the DISAT department. At the request of the student, the thesis can be combined with an internship in the same company.
See also https://www.ntn-snr.com/it
Deadline 30/03/2024
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