Mönchengladbach, April 30, 2018

Upgrade of the bar mill for Hyundai Steel Pohang with five-stand PSM®

An impressive evidence of how old technology can be used efficiently by targeted supplementation of hightech components.
  • The automotive industry demands ever closer tolerances from steel producers such as Hyundai Steel. To satisfy the requirements the company recently started relying on a five-stand PSM® from SMS group.
  • The hydraulic adjustment features the technology at Hyundai Steel. The rolling gap can be changed during the rolling process within milliseconds and the result is a considerably more precise diameter tolerance.

Since the eighties, Hyundai Steel has originally produced only rebars in its Pohang plant. In the course of time, the product range has been enlarged by SBQ grades. In order to meet the latest requirements of the automotive industry with regard to close tolerances, place has been created for the five-stand PSM® by shifting four stands in the intermediate train. With this relatively small extent of conversion work, Hyundai Steel was able to make the plant fit and profitable for the automotive sector. With the PSM® many different SBQ grades in the diameter range from 25 to 83 millimeters can be rolled economically on the existing cooling bed in small batch sizes and with high precision.

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The existing roughing and intermediate train
More precise than required by DIN standards

A particular feature of PSM® is the hydraulic adjustment under load enabling the rolling gap to be changed during the rolling process within milliseconds. The 3-roll PSM® achieves a diameter tolerance which is six to ten times more precise than requested by the DIN standard, namely temperature-independent over the total length of the bar. The requirement for near-net-shape rolling is thus fully satisfied. Another advantage is the rolling in free-size mode also enabling all intermediate sizes to be produced. Consequently, Hyundai Steel is able to consider e.g. the peeling dimension of a bar, reducing it to a minimum.

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View of rake-type cooling bed
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PSM® with downstream rebar mill stands
Electrical and automation systems

In addition to mechanical equipment, the scope of supply of PSM® also included electrical and automation systems. A fully automated rolling process is monitored and controlled by electrical and automation systems of SMS group. The core element is the performance module TCS – Technological Control System, controlling the hydraulic roll adjustment. A clearly structured user interface graphically visualizes all parameters. The automation system of SMS group is designed in such a way that existing measuring equipment of Hyundai Steel could be seamlessly integrated.

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View into the control stand
Roll change and roll shop

For a roll change the prepared PSM® mill stands are transported on a change car from the roll shop equipped by SMS group to the change position. As soon as the stands are available in exchange position the change procedure can begin. In the event of minor dimension changes,not all five stands have to be exchanged reducing work and expenses. Extension and retraction of the stands is fully automatic. What’s more, automation is already properly preset since the position of the roll rings has been transmitted from the roll shop in advance. A dimension change or exchange of used stands can therefore be completely finished within a few minutes.

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Exchange unitready for replacement
Assembly

The conversion work at Hyundai could be performed in a short period of time because each PSM® had been completely manufactured and already assembled in the SMS group workshop in Mönchengladbach. In just two large portions, the mill was transported directly to the construction site. Consequently, on-site assembly could take place quickly, reducing downtimes specifically for modernization projects to a minimum as in the case of Hyundai Steel.

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PSM® during assembly in SMS group workshop