The seamless tube rolling mill is 45 years old

The seamless tube rolling mill is 45 years old

This year we commemorate the 45th anniversary of the ceremonial opening of the tube rolling mill in Podbrezová. In almost half a century, the mill has undergone several upgrades not only improve operations but also the wider production range in terms of tube dimensions.

If we were to delve deeper into history, we would discover that the Podbrezova ironworks, as early as 1883, became the first a factory for the production of rolled tubes in the Austro-Hungarian monarchy. The tube production has continued without interruption from the aforementioned period until today. It is reasonable to assume that in every historical period, the factory primarily addressed the challenge of improving technology and modernizing tube production in its development program.

Over 45 years, the rolling mill has undergone many significant improvements related to the product range, production structure, innovation and modernization of technological equipment and control systems. Thanks to the implementation of these improvements, today the rolling line for the production of hot seamless tubes ranks among the world’s foremost rolling mills.
In the initial years following the commencement of production, the proportion of tubes (hollow shells) intended for further processing by cold drawing reached up to 70%. Out of the remaining 30%, only 6% was designated for export. About a decade after its inauguration, a significant shift in the production structure took place.

The share of “hollow shell” production has dropped to the current level of 35 % and the share of exports has grown significantly and today it accounts for up to 96 % of the sales of rolled tubes. The notable rise in export volume necessitated investments in new finishing equipment, including tube straightening, pressurization, color marking, and stamping. Additionally, measures such as preserving the surface of tubes with UV varnish for overseas transportation and geometrically packing them into hexagonal formations were implemented.

The escalating quality standards necessitated additional modernization efforts. In 1995, the so-called small program was introduced, which made it possible to expand the assortment of rolled tubes by diameters between 21.3 to 30 mm. In 1997, we proceeded with modernizing the control of the tube rolling process in the stretch reducing mill, leading to enhanced dimensional accuracy and a consequential significant boost in competitiveness in the global market.

In the same year, an advanced heating control system was implemented in the carousel furnace, facilitating uniform heating across the batch’s cross-section and reducing natural gas consumption. In order to further saving natural gas, the structure of the carousel furnace’s ceiling was modified from a vaulted shape to a flat design. Simultaneously, the outdated brick lining of the furnace started being replaced with a modern lining composed of hot concrete prefabricated elements.

The company constantly improving production process

Management’s focus on higher value-added products such as alloy boiler tubes or tubes for the automotive industry has led to additional investments. The reconstruction of the step furnace marked a substantial advancement in the technical capabilities regarding hollow heating before reduction. The adoption of a modern system of regenerative pulse burners, along with changes in refractory materials and adjustments to the furnace’s working space geometry, enables rapid adjustment to the required furnace temperature, reduces natural gas consumption by up to 25%, and ensures more uniform heating of the hollow.

In addition to the investment initiatives mentioned earlier, several organizational and technical measures were implemented to enhance performance, efficiency, and product quality, while also ensuring the technological equipment was maintained at the required level. The technologists at the seamless tube rolling mill have optimized the geometry of the push bench rollers and production deployment plan that have improved the material flow during mandrel bar rolling.

The modern hard metal rollers used in the push bench surpass the lifespan of the rollers used in the past. This improvement is partly attributed to the implementation of a new system for roller positioning in the roll stands. It was crucial to adjust the production order planning with a gradual prioritization towards extending the length of the hollow and deploying mandrel bars in alignment with the length of the hardened layer.

The most notable technological upgrades to the equipment park in recent years include:

• In 2015, the CARTA control system was installed in the stretch reducing mill, enabling the optimization of rolling parameters. Currently, the CEC module, which controls the length of accumulation or buildup of excess material at the ends of the tubes, is undergoing optimization.
• In December 2015, we successfully deployed a new equipment for cooling the rolls of the stretch reducing mill
• Between 2017 and 2020, the technological park of the seamless tube rolling mill underwent a complete overhaul. This included the replacement of the bloom cutting shear, elongating mill, initial part of push bench, installation of a new three-part cam bar (rib bar) in the push bench and rolling off mill.
• In 2020, the method of cutting tubes behind the cooling bed was upgraded with the installation of modern FRAMAG saws.
• In 2022, a third lubrication drum for mandrel rods was introduced. This allows the mandrel rods to exit the heating process directly through the lubrication drum, reducing downtime during mandrel rod set replacements. Additionally, to conserve gas, the recuperator of the carousel furnace was replaced.
• The inaugural tube laser marking system was commissioned at the seamless tube rolling mill. The laser is situated upstream of the preservation line.
• The saw used for cutting and shortening mandrel bars was also refurbished.
• In 2023, investments were made to enhance the quality and productivity of the pipes manufactured at our facility, with ongoing initiatives continuing into the current year. The investments included the acquisition of a new ultrasound system, a device for quickly sawing untested ends, rapid low-voltage embossing on line no. 1 LKR, a new Ohler saw no. 2, a new rotor for the push bench engine, and a revamped elongator control system.

Here are some significant milestones from the mill modern history:

• In 2017, we achieved a significant milestone by surpassing the “magical” threshold of 200,000 tons of manufactured tubes for the first time.
• In 2017, we achieved our highest production for sale in history, totaling 137,053.6 tons.
• 2018 – we achieved the historically highest production of 208,418.5 tons of tubes
• In 2018, the highest loading goods with 138,530.5 tons of shipped tubes. The construction of the new AS3 automated warehouse played a pivotal role in reaching this milestone.
• As of March 1, 2024, the seamless tube rolling mill produced 6.952 million tons of tubes, equivalent to 40,293,477 pieces of hollow shells.
• By March 1, 2024, sales of rolled tubes reached 4.231 million tons.
• by March 1, 2024, 2.721 million tons were further processed into precision tubes and fittings.

Article written by: Podbrezovan

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