Unique 4-Roll Plate Bending Machine for Producing Cylindrical and Conical Shells
The supporting yoke design on this 4-roll plate bending machine from Graebener-Reika can be hydraulically adjusted to counteract the respective bending forces, enabling processing of a wider variety of material thicknesses for multiple competitive advantages.
Graebener-Reika, Inc. (GRI; Reading, PA), a provider of machinery for processing tube, pipe, bar, plate and sheet metal, offers a unique 4-roll plate bending machine for producing cylindrical and conical shells.
A key differentiator found only on Graebener machines is the supporting yoke design, which can be hydraulically adjusted to counteract the respective bending forces, enabling processing of a wider variety of material thicknesses.
The supporting yoke clamps the top and bottom rolls and compensates for deflection by applying counter pressure to the rolls. This enables the ability to install a top roll with a smaller diameter, which can then allow bending of smaller inner pipe diameters.
Camber adjustments at the rolls are no longer necessary as bending capacity turns into pre-bending capacity, eliminating the need for predefined production programs. This increases the machine’s flexibility and reduces change-over times for exchange rolls. Companies can now form plates without limitation, from smaller thicknesses to thicknesses of up to 150 mm.
The supporting yoke can be equipped with a quick-change device, which allows dismantling in a very short period of time, or it can be fully sunk below ﬂoor level so that the machine resembles a conventional 4-roll bending machine.
This machine is the first 4-roll design where the supporting yoke can entirely be detached from the foundation during the bending process. The supporting column, as a bending aid for pipes with large diameters, is no longer braced to the machine foundation, but is self– supporting.
“What initially looks like an oversized machine giant is actually the most high-tech bending machine on the market today,” said Rich Marando, the president of Graebener-Reika.“Our supporting yoke design eliminates strain on the foundation and workshop, and improves productivity. We have some customers producing 10 pipes per shift.”
This self-supporting feature on this 4-roll bending machine enables a smaller footprint. The compact design of the machine is even more illustrated when most of the machine is embedded in the foundation.
Other advantages delivered by this machine include producing plate edges that are always parallel making convex respectively concavely shaped pipes a thing of the past. This creates optimum pre-conditions for welding processes. Additionally, the plate edges can be pre-bent without visible straight ends, which considerably reduces calibration efforts while maintaining the required tolerances.
These machines are especially well-suited to walled offshore wind tower sections, piles, mooring posts, large vessels, and tank applications. The supporting yoke system can also be retrofitted to existing equipment.