Optimizing of Coiler Threading Lengths in Steckel Mill Hot Rolling : An Investigation of Possible Parameters Affecting Coiling Behavior

Sammanfattning

This study investigates parameters affecting threading lengths in the Steckel mill coilers at Outokumpu Avesta during hot rolling of stainless steel strips. Incorrect threading may cause strip impacts, threading failures, equipment wear, production disturbances and reduced process stability. The study focused on how strip velocity estimation and forward slip calculations influence position prediction during threading. The work combines theoretical analysis, process data evaluation, production observations and investigation of the machine control logic. Process signals were analyzed using IbaAnalyzer and Power BI. Several stainless steel grades were studied to evaluate relationships between coiler vibrations and roll parameters such as rolling temperature, rolling speed, roll quality and slip factor. Additional analysis of 304L compared machine based strip velocities with approximated actual velocities calculated from hot metal detector (HMD) sensor timing. The results showed that several process parameters influenced the measured vibrations, although the relationships were inconsistent between different steel grades. The investigation showed that strip position prediction depends heavily on a reduction-based forward slip model used to estimate strip velocity. Comparisons between machine based and estimated velocities indicated significant slip estimation differences. The study suggests that adaptive and measurement based velocity correction methods could improve the threading stability and process reliability in Steckel mill hot rolling.