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New Dimensions in Seamless Ring-Rolling Technology

SMS Group stretching the boundaries of the forming-rolling process with new machine for Chinese forger

The past year has been a prolific one for the advance of ring-rolling technologies, with new capital investments and new operations demonstrating the advances that process designers have made in dimensional control (and consistency) for large rings. The next step will be to expand the dimensional limits of the finished products.

Shandong Iraeta Heavy Industry Co., Ltd. (SIHI) ordered a new, radial-axial ring-rolling machine from SMS Group that will establish a new limit – 16 meters – for seamless rings. The maximum ring height will be 3 meters. When the machine (the SMS designation is “RAW 2500/1250-16000/3000”) starts up late this year at the SIHI plant in Zhangqiu, Shandong, SIHI will be the only company in the world capable of rolling seamless rings in these dimensions.

The capital investment value of the project has not been announced. The prospect of seamless rings up to 16-m diameter “opens up opportunities for us to serve the market with new ring dimensions, and hence to expand our product portfolio,” according to SIHIH president Yugang Niu.

Seamless rings of those dimensions are needed in infrastructure projects, specifically for power and energy systems. For example, tower flanges on wind turbines require rotating bearings of such scale, with the particular requirement for extreme load bearing. Another likely application is the structural frame for large pressure vessels used in nuclear power reactors.

SIHI is joint venture of Spain’s Gonvarri Group and the former Shandong Iraeta Wind Power Flange Manufacturing Co., with more than 800 workers and three production lines forging flanges; large rings for wind tower connectors, yaw rings, and bearing rings, etc.; and very large rings weighing more than 20 tons. In addition to forging, production capabilities include heat treatment, machining, and ultrasonic testing. Total annual production capacity tops 200,000 thousand tons.

During radial-axial ring rolling, the cross-section of a ring blank is reduced in a combined forming process, meaning that the thickness and height of a workpiece are reduced simultaneously. As a result, the ring diameter expands due to the constant volume of the workpiece.

With the new machine, SIHI will increase its production capacity for rings made from blanks weighing up to 200 tons. The ring-rolling machine will be equipped with advanced sensor technology and machine process control, and it will be supported with a dedicated power control system that constantly adapts the available supply to the energy requirements of the forming process, maximizing plant power availability while preventing machine overloading.

“The development was a great technological challenge,” commented Robert Düser of SMS’s Forging Plants/Ring and Wheel Rolling division. “The experience that we have gained here will help us to considerably expand the capacities of our ring rolling machines, opening up completely new markets for our customers.”

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