Bending Presses

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Hydraulic press brakes operate in the field of sheet metal  forming. Also in this sector Duplomatic MS is present with the press units designed and manufactured in the Hydraulic System Business Unit.

The prerogative of these machines is the precision of movement in synchronism and the final precision of the bending phase that requires positioning accuracies in the order of 0.02-0.03 mm. Each cylinder is controlled in closed loop with digital feedback.

Press brakes are considered dangerous machines under the Machinery Directive and therefore require a special circuit in which the certified monitored valves are present.

Precisely because of this peculiarity, the circuit diagram and the number of valves  with spool position monitoring must be agreed with the certifying body of the press.

In the operation of the press brakes, the performance of the proportional valves that manage the two axes (cylinders) in synchronism and in closed loop of position is fundamental. The choice between "spool in body" proportional valve and  DXE3J “spool in sleeve” servoproportional valve depends not so much on the final precision that is excellent with both solutions, but mainly on the rapid speed of the press. The tendency of manufacturers is to raise the ratio between the sections of the cylinders to increase the ascent speed and at the same time they also tend to increase the rapid speed of descent in order to decrease cycle times. This means requiring more and more dynamics from the valves. In addition, the high ratio between the cylinder areas requires the presence of overpressure valves on the annular chamber as a safety against pressure multiplication which would be particularly high.

For machines with approach speeds up to 10-12 m/sec,  it is possible to use the DSE3J-Z* proportional valves, which, being "spool in body", have a low cost and offer performance in line with the needs of the press manufacturer.

When fast speeds are higher, servoproportional valves are essential.

The solutions proposed by Duplomatic MS are in line with the needs of the major Italian and foreign manufacturers and comply with the requests of the main certification bodies.

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