Modeling of the process temperature of NC form grinding processes on single grain basis considering the grain wear and the grain load depending on the cooling lubrication strategy

In grinding processes, friction, small chip cavities, the ploughing effect and a large number of simultaneous grain engagements result in high process temperatures. These can cause thermal damage to the surface of the workpiece and the tool and lead to changes in the microstructure of the material (white layer) or residual stresses in the edge zone. Knowledge of the resulting process temperature is of central importance for damage-free manufacturing. Modeling process temperatures is a good way to modify process parameters in advance to prevent thermal damage to the edge zone of the workpiece. Often, the heat transfer coefficient is approximated iteratively by using numerical simulations and a workpiece temperature, which is determined by using thermocouples at a defined distance from the workpiece surface.

In this project, an innovative approach for modeling of process temperature on a single-grain basis is developed, which enables a time-efficient and realistic simulation of the process temperature. The influence of the cooling lubrication strategy as well as the wear progress of the tool shall be taken into account. The single grain temperature is empirically measured by cutting the fiber of a two-color pyrometer in the NC form grinding process using cooling lubricant. The systematic relation between the single grain engagement and the single grain temperature will be investigated by means of different parameters such as the chip cross section, the rake angle or the flank angle. These investigations will be based on a grinding process simulation, which has been developed in a previous research project. For this purpose, single grains whose temperature has been determined experimentally will be identified by simulating the workpiece surface and analyzed with respect to their engagement situation and the cooling strategy for different wear conditions. The knowledge obtained will be used to develop a temperature model based on individual grains, which can calculate the process temperature at the workpiece surface taking into account the parameters mentioned. In order to be able to represent the influence of the coolant strategy implicitly without having to model it explicitly, the influence of the nozzle configuration during coolant supply on the developing single grain temperature is taken into account for the calibration of the model. The temperature model can be used to derive a more sustainable use of coolant for process planning, e.g. through a reduced pump capacity with a corresponding nozzle configuration.