Heavy plate bending press for thick high-strength and wear-resistant steel

01

Size the press force per metre for your hardest grade

SSAB's press-brake guidance lists calculated forces to bend its grades to 90° along the rolling direction, as press force per metre of bend length: at 10 mm, 630 kN/m for SSAB Domex 355MC, 1,170 kN/m for Strenx 700MC, 1,340 kN/m for Strenx 1100E, 1,380 kN/m for Hardox 450 and 1,570 kN/m for Hardox 500 Tuf; at 15 mm, 950, 2,010, 2,070 and 2,370 kN/m for Domex 355MC, Strenx 1100E, Hardox 450 and Hardox 500 Tuf. [1]

SSAB states that the estimate depends on bend length, plate thickness, die width, tensile strength and the changing moment arm, with the peak load at a bend opening angle of 120° under normal friction without lubrication; a wider die reduces the force, as does a smaller punch radius, and trial tests are always recommended. [1]

Editorial calculation: a 3 m bend in 10 mm Hardox 450 needs 1,380 × 3 = 4,140 kN, about 422 t (÷ 9.807), while the same bend in Domex 355MC needs 630 × 3 = 1,890 kN, about 193 t: 2.2 times the force for the same plate thickness. A 6 m bend in 15 mm Hardox 500 Tuf needs 2,370 × 6 = 14,220 kN, about 1,450 t. Add margin and use the supplier's tonnage chart for your die.

Give the supplier the hardest grade and thickest plate, longest bend, die widths and punch radii you plan, part weight and size, required angle accuracy, part handling (sheet supports, front gauges, manipulators), and the floor space and foundation available.

02

Plan the overbend for springback

SSAB explains that springback increases with steel strength and with the ratio of die width to plate thickness (W/t), and that high-strength steel cannot be bent to 90° in a die with a 90° opening; the die must allow overbending beyond the final angle. [2]

Values are SSAB's BendCalc results for bending to 90° to its recommendations, longitudinal to the rolling direction. [2] Editorial calculation: to finish 10 mm Hardox 500 Tuf at 90°, the tooling must let the part close to about 90 − 19 = 71° under load, so the die and punch angles must clear that, while Domex 355MC needs only about 4°.

03

Check the frame, stroke and tooling windows

Ursviken's Optima, a custom-engineered press brake for plate fabrication, large poles, pipes, crane arms and thick high-strength plate, is specified at 400 to over 5,000 t press force, 4,100–20,200 mm maximum bend length, 3,100–16,200 mm between side frames, 485–4,000 mm tool space and 300–1,500 mm stroke. [3]

Ursviken's options for such presses include segmented Flexicrown crowning for local corrections, angle control with automatic compensation, tool magazines and CNC lift-swing handling, and an EcoPump that it says cuts energy use by up to 95% by setting motor frequency per bending cycle. [3]

Its Variable Die Tool changes die opening under CNC instead of swapping heavy dies, with an opening range of 28 mm to 915+ mm and sizes of 28–124, 32–200, 40–260 and 50–370 mm; Ursviken states that it withstands much higher loads than single V-dies and can make non-symmetrical bends for offsets. [4] Editorial calculation, assuming a die opening ten times plate thickness: 30 mm plate needs a 300 mm opening, inside the 50–370 mm size. SSAB notes that a wider die lowers the force [1] but raises springback [2], so fix the die width with the supplier for each grade.

04

Frame, hydraulic drive, crowning and tooling of a heavy plate bending press

05

Tonnage per metre of bend length, plus throat depth for deep flanges

06

Send grades, plate sizes and tooling plans together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Material: [grades; thickest plate; tensile strength]
Bends: [longest bend; angles; inside radii]
Tooling: [die widths; punch radii; overbend; variable die]
Machine: [force; bend length; stroke; tool space; throat]
Accuracy: [angle; crowning; angle control]
Handling: [part weight; supports; manipulators]
Site: [foundation; power; crane]

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