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Iranian experts acquire knowhow of machining hot rolling stands


Experts of Mobarakeh Steel Company – in cooperation with specialists from domestic companies – have successfully completed the machining process of final rolling stands and installation of new balancing blocks during the annual overhaul of MSC’s hot rolling mills.
Morteza Ramezani, the head of the technical office of hot rolling unit, said the annual stoppage for maintenance of the hot rolling was one of the biggest repair stoppages in Mobarakeh Steel Company, adding the overhaul which was the first in the country took the Central Repair unit three years of planning and more than 70,000 man-hours. Eleven contracting companies along with MSC’s hot rolling unit were part of the overhaul process which lasted three weeks.
Nima Davari, a technical expert of the hot rolling unit, said in light of erosion occurring in the hot rolling stands and a rise in equipment failures and emergency halts which could have caused heavy damage, the company’s management put the overhaul process top on its agenda. “The company started to conduct an expert study into the overhaul process three years ago and planned for the overhaul of the hot rolling stands and the machining of the final stands. After the plan was confirmed, the defects of the process were meticulously spotted in the first phase. Building on expert reports, the process of picking the qualified contractors for handling the overhaul got under way.”
In the second phase, he said, the company employed the laser tracker technology to collect data and analyze the status of stands during last year’s annual shutdown so that it could come up with a final plan for machining and changing the design of the balancing block of the final rolling stands. “In the third phase, preparations were made to successfully initiate the machining process of final rolling stands and installation of new balancing blocks. All this materialized on the back of tireless efforts and determination of staff in different units.”
The company achieved its stated objectives as all processes including machining, measuring and installing were handled by domestic companies, he said. “The Iranian companies which participated in these processes have now acquired the related knowhow. Previously, foreign companies had a monopoly on the knowhow for the machining of the stands.”
In light of the fact that the prolonged annual halt was blamed on the machining process of the final rolling stands, the management of the hot rolling unit gave top priority to the optimal use of time and the overhaul, he said, adding the following are some of the key measures the company has taken in this regard:
 
 
Slab yard and preheating furnaces
In this part, the company handled the adjustment and exchange of supports for discharge rolls and extractors of Furnaces No. 1 and 2; repair of the metal structure of Camps No. 1 and 2 of slab yard; repair of concrete foundations of Furnaces No. 3 and 4; repair of the metal motor structure of Furnaces No. 3 and 4; repair of the refractories of all furnaces; and the overhaul of Furnace No. 3 and replacement of GR6 transmission (Askarel).
Roughing
In this part, the company successfully implemented the following: machining of the rear part of upper support liners and balancing blocks of roughing stand (R3); machining of roller tables; repairing the metal structure of stand E1; replacing the cylinders and beam screwdown of stand R1; repairing base side guide of stand R3 entrance; replacing GR1 transmission; and doing routine repairs of main engines of the roughing rolls.
Final rolling or finishing
The following were implemented in this part: machining of the final rolling stands, improving the finishing shears, optimizing stand F4 looper (changing the hydraulic system to an electric system), correcting the location of stand F7 capsule, changing F6 stand’s armature, and handling the routine repairs of main engines of the final rolling.
Coilers
In this part, the hydraulic system of Coiler No. 1 was changed from H6 to H16 system. The fixed plate of Coiler No. 2 and the pinch roll frame of Coiler No. 3 were also replaced. The side guide of Coiler No. 2 was repaired and the Parsytec coiler was optimized.    
Overhead cranes
Rail camps No. 1, 2 and 3 of the slab yard, single-girder overhead Crane No. 12 of rolling workshop, its electrical rails and busbars, and the rails of the rawmill at hot rolling unit were all corrected. Trolley rails of the Crane No. 12 of the roller workshop and its base gearbox were replaced and the access passageway for Crane No. 18 of the hot rolling was installed.
Hot rolling completion unit
In parallel with the annual stoppage at skin pass rolling, the conveyor of the hot rolling unit underwent an overhaul at the hot rolling completion unit.
In conclusion, Morteza Ramezani said the project was implemented thanks to the steely determination of staff members of Mobarakeh Steel Company and valuable contributions by Max Part Company, Abad Deghat Markazi (ADM) Co., [Safir] Naghshe Negar Co., Tom Iran-Khodro Corporation, Sohan Azar Parsa Company, IRANCART Company (ICC) Private Joint Stock, Koosheh Sazan Company, Dozhpad Company, Behsazan [Engineering] Company, Taban Niroo Company, Bargh Ara Engineering Company, Kavir Company, and Soleimani Company. He thanked them all for their tireless efforts.


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