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Active lubricated guidance for precision tool machines based on adaptive valves and fluids

Active lubricated guidance for precision tool machines based on adaptive valves and fluids

The research work presented in this report had the objective of advancing knowledge on pressurised lubricated hydrostatic, hydrodynamic and hybrid slideways. Work with conventional fluids and magnetic fluids was carried out, and in both cases improved performance with respect to conventional passive solutions and an advanced active response was achieved.

In the development of lubrication based on conventional mineral oil (Newtonian fluids), a calculation tool was produced which predicted the behaviour of radial, axial and linear slideway bearings; all geared towards its use during the design phase of machine tools. The models were validated by means of a new test bed on which the radial bearing prototypes were analysed. The new test bed was used to isolate the behaviour of the radial bearing to be analysed with respect to the rest of the system, an effect that in traditional test beds limits their characterisation. To end with lubrication solutions using conventional fluids, an adaptive valve was developed based on flexible diaphragms; and, furthermore, a self-compensating lubrication solution based on internal ducts in the slideway itself. These developments were both theoretical, based on fluid dynamic models, and experimental on individual test beds.

The next large research block presented in this report is aimed at the use of magnetic fluids to obtain active lubrication. Work was carried out with magnetorheological and ferrofluids, in which, after carrying out a synthesis activity to acquire a basic knowledge of their composition, an in-depth experimental characterisation was performed of two commercial fluids; the two fluids that were used during the research. The theoretical model was developed supported by its respective test bed for the study of radial bearings, both hydrodynamic and hydrostatic. For the latter, magnetorheological valves were also developed  which controlled the feed flow. In this research, the improvement of the linearity in the hydrodynamic lubrication was ascertained, as well as the infinite rigidity with the magnetorheological valves controlled in a closed loop. Finally, a sealing joint was developed based on magnetic fluids, where the ferrofluids demonstrated a behaviour compatible with the requirements of precision machine-tool heads.


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