Colloquia

Samenvatting

Abrasive tool wear is a common phenomenon in hot forming operations, due to the high temperatures and lack of lubrication. Abrasive wear is the removal of material from the tool. The condition of the tool has a direct influence on the quality of the product. When severe tool wear occurs, the quality of the product becomes insufficient and the tool needs to be repaired or replaced. Therefore, it is of interest to predict the location and severity of tool wear.

The aim of this research is to develop an abrasive tool wear model for hot forming operations, so manufacturers can simulate the tool wear and predict the tool life time. Volvo Cars provided a data set with the simulation and tool scans of an A-pillar to develop this model. A sensitivity study is conducted to find a correlation between process parameters and the amount of tool wear. This resulted in a promising model. The model determines the amount of tool wear based on the dissipation of energy and has a variable wear coefficient. The nonlinear development of tool wear is incorporated in the model by relating the wear coefficient to the sliding distance.

The model is calibrated for a tribological system with a boron steel with AlSi coating and an uncoated tool steel 1.2344, which is a common system for hot forming operations. The model is validated on the lower dies of the Volvo Cars A-pillar. The validation shows that the model can successfully predict the locations where abrasive tool wear occurs. The severity of tool wear is accurate at locations which experience a significant sliding distance. In the areas with a small sliding distance the amount of tool wear is underestimated by a factor 10. An adjustment to the calibration procedure is proposed to solve this underestimation. The model can be used to predict the tool life time when an abrasive wear limit is provided.