Rourkela: The Dynamic Quality Circle (DQC) group of the plate mill department of Rourkela Steel Plant (RSP) has successfully eliminated delays caused by failures of the groove roll gearbox bridge. It was their innovative project titled “Elimination of Delay Due to Groove Roll Gearbox Bridge Failure” that led to the success. Notably, the plate mill relies on 12 groove rolls to feed slabs into the mill, with eight rolls, including one idle roll, on the entry side and four rolls on the delivery side. These groove rolls are powered by three gearboxes.
The Dynamic QC group identified that groove roll gearbox -2, positioned near the mill’s work roll, was particularly vulnerable to failures. The bridge of this gearbox, which supports the output gear train, frequently cracked at the welded joint due to uneven load conditions from the mill. These failures caused damage to both input and output gears resulting in significant delays, taking 10 to 12 hours to restore the gearbox to operational status.
Dynamic QC group SK Swain, deputy manager, JC Bisoi, MOMT, group leader, K Berik, OCT, Deputy leader, RP Hembrom, OCT, SK Behera, operator, S Sahoo, ACT and Anand Ekka, ACT found that while the outer sides of both bridges inside the gearbox were welded to the walls, the inner sides lacked vertical support. To resolve this, the team cut two plates, each 20 mm thick, to fit into the blank spaces between the bridges. These plates were then fabricated and welded vertically to the bridges and the bottom of the gearbox, effectively transforming the two separate bridges into a single, sturdy structure.
This modification now ensures that any uneven load from the mill is evenly distributed between the bridges, preventing the stress points that previously caused the welds to crack. The innovative initiative has resulted in the complete elimination of delays caused by bridge failures enhancing production, performance and productivity.