TPT November 2011

A rticle

inductive; the generator is transistor-controlled in the frequency range between 80 and 140 kHz and represents state-of-the-art technology. The quality and functionality of the inside flash trimmer are decisive factors for the yield and for satisfying the product requirements. The patented inside flash trimmers supplied by SMS Meer allow very precise inside flash trimming (Figure 5). The very robust design permits smooth operation and has a considerable influence on the plant running time. For sizes with an inside diameter greater than 170mm, a self-supporting construction with a hydraulic shearing system is used, which chops the inside flash into short pieces. This system is of advantage when cutting the tubes and, in particular, when removing the inside flash from the tube later. The sizing section (Figure 6) is equipped with a de-twisting stand, 4 sizing stands of 4-roll design and a universal Turk’s head.

Figure 2 : Forming section

Wall thicknesses up to 16mm and material grades up to 800N/mm² need sturdy equipment and drives. The strip preparation line and the spiral strip accumulator are designed for filling speeds up to 120m/min. The cross-welder with integrated crop shears positions, measures, crops and connects the strip ends almost fully automatically. Thanks to the high filling speed and the short coil connecting time, a very flexible production with high production speeds is ensured (Figure 1). The forming section and the sizing section form the heart of the plant. High-quality forming of sophisticated and variable products, allowing the use of modern high-strength materials, can only be achieved by means of an individually adapted roll set. The use of universal or straightedge forming concepts is not acceptable. The plant is configured with 5 breakdown stands followed by one side closer each, 3 fin-pass stands (of 4-roll design) and a 5-roll welding stand (Figure 2). The so-called W-forming (Figure 3) allows the production of thick- walled sizes such as 114.3 x 15mm or 139.7 x 16mm. All stands are designed as URD ® stands, thus ensuring an extremely high deformation rigidity, which, in turn, enables a high and uniform product quality (Figure 4). Heating of the strip edges to welding temperature is effected by means of an SMS Elotherm 1,200 kW HF generator. Heating is

Figure 4 : URD ® stand design

Figure 5 : Inside scarfer with integrated hydraulic chopper

Figure 3 : Breakdown stand

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N ovember 2011

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