Resumo:
The design was developed to optimize the time of the shifting of the work rolls in the Hot Strip Mill. With this, the objective was to increase the availability of the mill, eliminating losses and increasing the annual volume produced. The main problem is focused on the time of movement of the rolls after the rolling process. This task is performed after a time about five minutes for each set of rolls and with the mill stopped. The cumulative loss for this time is very high during the month, with a potential gain of around one day of production of coils. This movement is accomplished through the crane and an exchange device (lifting tong) that attaches to the rolls to be transported from the Mill to the Roll Shop. The critical path of the project is to automate this lifting tong by allowing the operator to coupling the device through a remotely operated hydraulic system, enabling the operator to perform the activity at a safe distance from the load, thereby eliminating the need for consign the mill. An autonomous hydraulic system (UPS) was developed, remotely actuated by the operator, eliminating the need for manual coupling of the transport device in the rolls. With this improvement, we have eliminated the need to stop the mill to perform the activity. In the development of the work were used the Rapid Tool Exchange (TRF) and MASP methodologies to propose ideas solutions and analyze the feasibility and safety of the project. After the analysis, the PDCA methodology was used to develop and plan the execution. As a result, after the implementation of the project, there was no further occurrence of production stoppage due to the movement of rolls after the change. We eliminated about 17% of total minutes from the mill stoppage only for this special cause, which represents a production increase about 3% of tons of rolled coils per month. Another significant gain was with regard to the safety and ergonomics of the operators at the time of the exchange, where we reduced the human machine interface, repetitive efforts and the need of operators to be close to suspended loads.
