Bending rolls

Precision during parallelism and positioning sequences

Bending rolls are machines used for the metal deformation; they usually turn a plane sheet into a more complex tubular shape, mainly round or elliptical.

At first sight they appear extremely easy to be designed and managed; in the reality these machines require accuracy and precision to obtain a quality product. They stand out for the dimension (length of the product) and for the thicknesses that can be processed.

Duplomatic is a leader in supplying systems for small (metal thickness up to 10 mm.), medium and medium-large benders (thicknesses higher than 50 mm.).

The hydraulic circuit for simple benders usually requires series cylinders with the possibility to change the inclination angle. The cylinder positioning speed is constant and the need to use the circuit with slowing down feature for precise positioning procedures is rare. Such a circuit is normally applied to low-power benders, as the strength of a series circuit is calculated only on the section of the main cylinder rod. Higher powers would require very big cylinders.

More powerful benders need a parallel circuit with mechanical (by now rarely used) or electronic devices aimed at controlling parallelism and final positioning.

A special application worth to be mentioned is the handling with interpolated axes for the roller leveling of the big truck tanks containing diesel fuel. The elliptical shape of these tanks requires extreme precision during the roller welding process so that the edges can properly fit together for the welding.

Furthermore, considering that series production is involved, the time required by the roller welding procedure must be as short as possible.

The bender is equipped with a 12-axis control and the position parallelism of each roller is strictly controlled. Each roller is also interpolated with the hydraulic motor which controls the rotation of the 4 rollers (lateral + pliers + higher roller) connected to each other through a mechanical device.

This system is provided with servo proportional valves type DXJ3-DOL* with a ±10 Vdc signal in order to ensure a degree of parallelism and positioning precision lower than the tenth of a millimeter.