TENSION LEVELING OF ELECTRICAL SHEET USIN G A MECHANICAL TENSION BRIDLE AS A TENSION UNIT

An ''Umlauf'' or mechanical plate-type chain tension bridle was instal led as a tension unit in the exit of a tension levelling line. On this line, annealed and temper-rolled semi-finished electrical sheet was t ension-levelled with different elongations. The intention was to exami ne whether the critical cold reduction which initiates the grain growt h during the final anneal can be imparted by tension levelling alone o r also by a combination of temper rolling and tension levelling, and h ow this improves the magnetic properties. In addition, it was to be de termined whether the correction of coilset (longbow) and crossbow is p ossible. An ''Umlauf'' or plate-type chain tension bridle was integrat ed in place of a tension roll assembly in a tension levelling line. Wi th this arrangement it was possible to easily achieve elongations in t he order of 9% for annealed strip, and total elongations in the order of 9.4% for annealed and temper-rolled strip. Coilset (longbow) and cr ossbow were corrected by means of the bending roll and correction roll settings. A distribution of tension builds up between the tension lev eller and the tension unit which is consistent with the fibre length d ifferences remaining over the strip width after the levelling process. Up to elongations of around 6%, continuous furnace annealed and tensi on-levelled strip exhibits reduced core losses. If the annealed strip is temper-rolled prior to the tension levelling, such losses are signi ficantly lower, with polarisation values undiminished.