In-situ temperature measurement in the shearing zone during sheet metal blanking

Blanking is one of the most widely used manufacturing technologies in sheet metal processing, because nearly each sheet must be trimmed out of a semi-finished part or has to be blanked after a forming process to get the precast part in the manufacturing chain. In general, a high quantity of blanked parts should be manufactured without reworking the tool. Therefore a capable process is indispensable to avoid inadequate part quality or premature failure of the tool because of wear. The blanking process is affected by tool parameters, the press and the material properties of the blanked part. However, another important factor is the occurring temperature in the shearing zone of the sheet metal due to the dissipation of nearly 95% of the plastic work during blanking and, in addition, frictional heating. This temperature impacts the blanking process features such as tool-wear and resulting cut edge quality. It has been presumed to be negligible by a lot of authors yet. In contrast some publications with experimental and analytical research assume that the temperature reaches values up to 1000°C. Therefore, this report outlines a thermoelectric method to measure the resulting temperature distribution during the blanking process on the cutting edge of the blanking punch. The feasibility of the investigated measurement concept is shown on a concrete example.