Simulation Studies on Centrifugal MQL-CCA Method of Applying Coolant during Internal Cylindrical Grinding Process

Abstract

This paper describes simulation studies regarding the application of the centrifugal minimum quantity lubrication (MQL) method simultaneously with the delivery of a compressed cooled air (CCA) stream in the internal cylindrical grinding process. The idea of a new hybrid cooling and lubrication method connecting centrifugal (through a grinding wheel) lubrication by MQL with a CCA stream is described. The methodology of computational fluid dynamics (CFD) simulation studies, as well as the results of numerical simulations, are presented in detail. The aim of the simulations was to determine the most favourable geometrical and kinematic parameters of the system in the context of air-oil aerosol and CCA flow, as well as heat exchange. In the simulation, the variables were the grinding arbor geometrical parameters, the angle of CCA supply line outlets, and the grinding wheel and workpiece peripheral speed. As a result of the simulation studies, the most favourable geometrical parameters were designated, determining the orientation of the ends of the two CCA supply line outlets before and after the grinding zone, the number of openings in the drilled-out grinding arbor, and the influence of the grinding speed on the parameters of the coolant flow and temperature of objects in the grinding zone. In addition, the results of simulation tests made it possible to visualise the velocity vectors of the two-phase coolant flow in a complex system of air-oil aerosol delivery centrifugally through an open structure of a very fast rotating porous layer (grinding wheel), with an additional supply of CCA using an external cold air gun (CAG).

Modern Approach to Delivery Coolants, Lubricants and Antiadhesives in the Environmentally Friendly Grinding Processes

“…The results of numerical simulations [126] and experimental research [127] have shown that the developed hybrid method allows for about 2.7 times longer wheel life in comparison with the results obtained under flooded cooling or centrifugal MQL conditions. The wheel life was as much as 8 times longer in comparison with the wheel life under SSP only delivering or dry grinding conditions.…”

“…They were the motivation to undertake work aimed at applying the CAOM method also in the process of internal cylindrical grinding characterized by limited space in the contact zone of the grinding wheel with the workpiece. This is how the method was developed in which a patented centrifugal air-oil aerosol delivering through the grinding wheel [124] was combined while simultaneous incorporating the CAG nozzle into the system [125][126][127].…”

“…One end of the supply line was directed in front of the grinding zone to cool it down while the other end was placed directly behind the grinding wheel-workpiece contact zone to support the blowing out of machining products (Fig. 4) [126,127].…”

Experimental Studies on the Centrifugal MQL-CCA Method of Applying Coolant during the Internal Cylindrical Grinding Process

“…The aim was to determine the most favorable geometrical and kinematic parameters of the process in terms of the flow of cooling and lubricating media (air-oil aerosol and CCA), as well as heat exchange. The conditions and results of these simulations were described in detail in the paper [65]. The most advantageous of the variants analyzed in the simulation studies was then selected for experimental research, in which the service life of the grinding wheels was determined with reference to four methods of cooling and lubricating the machining zone.…”

“…The conditions and results of these simulations were described in detail in the paper [65]. The most advantageous of the variants analyzed in the simulation studies was then selected for experimental research, in which the service life of the grinding wheels was determined with reference to four methods of cooling and lubricating the machining zone.…”