Torsion Bar or Synchronized Press Brake

Torsion Bar or Synchronized
Press Brake

When choosing a Press Brake there are 2 possible specification options:
Torsion Bar or Synchronized
which specification suits your
precision, technical & budgetary requirements ?

Generally a Torsion Bar Press Brake specification offers a limited number of automatic axis options
Torsion Bar Press Brakes are not viewed as high accuracy high specification Press Brakes, the number of automatic axis generally being limited to
3 number automatic CNC controlled axis being [Y+X+R], the[Z] axis being manual, some manufacturers of Torsion Bar Press Brakes do offer automatic [Z1+Z2] axis
 Choice of CNC controllers is generally limited

A Synchronized Press Brake is the higher specification Press Brake,
offering a full range of automatic axis, these being: [Y1+Y2+X1+X2+R1+R2+Z1+Z2+X5], plus many options for
‘ancillary equipment’ & a large selection of CNC controllers
[ See our CNC control page ]

The Torsion Bar Press Brake achieves the required bending position of the Upper beam [the Y axis], with a motorised thread and nut
[known as dead stops] that are incorporated into each of the 2 individual hydraulic cylinders [Y1+Y2]
The revolutions of the dead stop nuts are driven with a motorized central single gearbox, the gearbox revolutions are measured by a rotary encoder.
With this system, the accuracy of achieving the target bend position of the combined [Y1+Y2] axis is [+ or – 0.10 mm] each stroke of the bending beam, so its possible for a 0.20 mm difference between 2 beam strokes

A Chinese Press Brake model W67Y is always a ‘Torsion Bar’ press brake.

Synchronized Press Brake:
electronic-hydraulic positional balancing of the bending beam
the individual [Y1+Y2] hydraulic cylinder positions

The required bending beam position is monitored by the reading of two individual linear encoders each situated at the [Y1 +Y2] axis
offering (+ or – 0.01 mm) precision with each stroke of the bending beam

The position of the attachment of the [Y1+Y2] encoders is important, the preferred method is the attachment being‘free of the machines frame’.

The significance of this is that, even if there is deformation in the machine structure during a bending cycle, the bending beam position is not affected, in other words, the angle calculated by the CNC is not subject to errors caused by deformation of the machines frame.

As you can see a Synchronized Press Brake is 10 times more accurate in positioning of the bending beam [Y1+Y2] axis than a Torsion Bar Press brake, however the relevance of such information depends very much upon the work to be undertaken. The accuracy of a Torsion Bar press brake is possibly not too important with heavier plate fabrications, but accuracy is more relevant for close tolerance sheet metal work, therefore a Synchronized Press Brake is preferred