Folding rule v. back stop in bending technology – a comparison
Learn what a folding rule is still good for and where a back stop already works automatically in our comparison of a folding rule versus a back stop – with all of the advantages and disadvantages.
OP3100 simple control system: calibrating with a folding rule
CP200 graphic control system: automatic calibration
Hydraulic bending machines w/o a back stop – calibrating with a folding rule
Place of use These kind of long, hydraulic bending machines, usually up to 6 metres in length, can be found in tinsmiths’ workshops; they bend the edges on the long sides of building site profiles or covers, for example.
Calibrating with a folding rule These machines do not have a back stop. The profile is inserted from the front and calibrated with a folding rule by 2 operators on the left and right; the profiles is clamped hydraulically by the upper clamping tool when a foot pedal of button on the control unit is pressed and the bending tool performs the bending movement hydraulically when the foot pedal – button on the control unit – is pressed again.
Preparation
- The operator has to calculate the processing for the cut on every sheet.
- Bending lines have to be marked individually on every bending profile; these marks are made with either a stylus, a centre punch or a small nick in the side of the sheet. The mark is aligned by hand along the bending line on the clamping tool. If no mark is made, the profile has to be calibrated and positioned on the left and right by the operator for every bend until it is correct.
- Corresponding records and calculations have to be made in advance for more complex profiles (tapered/overlapped profiles) to produce the exact profile.
- The sheet first has to be cut to length and then for the appropriate processing: on plate shears or roll shears hung in front of the bending machine – usually by hand, sometimes motorised. The operator has to calculate the shortened bending and take this into account.
Number of operators: 1 to 2 operators, 2 operators are needed for longer sheets
Machine control system
Simplest machine control systems: with option for programming, or up to 9 bending angles can be programmed; bending programs cannot be saved.
Advantages
+ Tinsmiths with folding rules and great expertise can produce masterpieces.
+ Little training required on the machine because it is very easy to operator.
+ Purchase price of machine lower than comparable bending machines with CNC control and an automatic back stop.
Disadvantages
- There is no automatic back stop, meaning that extensive manual preparation is needed that also calls for extensive know-how and patience.
- Recurrent bending profiles have to be calculated anew every time, drawn by hand, cut and bent manually; the repeat precision is relatively low.
- No graphic control system is available, so that every bending profile has to start “from scratch” because no dimensions, bending points, processes are known.
Hydraulic bending machines with tapered back stop – automatic calibration w/o a folding rule
Place of use These kind of long, hydraulic bending machines between 4 and 12.2 metres in length, can be found in tinsmiths’ workshops; they bend the edges on the long sides of longer parallel, tapered or overlapping building site profiles or covers.
Calibrating with an automatic back stop These machines have a tapered back stop that is automatically brought into the correct position in the machine before every bending step: parallel or tapered along the bending line of the clamping tool. The profile is inserted from the front before being moved up and aligned with the back stop fingers mounted on the aluminium beam. The profile is clamped hydraulically with the upper clamping tool after the foot pedal has been pressed, the bending tool pe4rforms the bending movement hydraulically after the foot pedal has been pressed again.
Preparation
- The sheet first has to be cut to length
Number of operators: Only 1 operator is needed for profiles up to 4 metres long; 2 operators are needed for lengths over 4 metres
Machine control system Graphic control system, for example CP200 graphic control system:
- A structured profile library with more than pre-defined 350 profiles is already provided on delivery.
- For profiles that do not yet exist: create a profile with the finger in sketch mode, including dimensions and angles; mirror and copy function for profile elements, for example for a trapezoidal profile; tapered and multi-overlapping bending profiles (with a gradient) can be drawn and defined easily. The control system calculates the dimension of the individual profile automatically, as well as the necessary position of the stops for each bending profile, to achieve the programmed shank lengths at both profile ends.
- Bending profiles can be copied, adapted to the specific building site and saved automatically with just a few clicks.
- Automatic bending sequence calculation to keep turning the profile around and over to a minimum.
- Simulation mode to prevent possible collisions before bending.
- Automatic springback compensation depending on the type of material and bending angle
- Cut calculation based on the neutral phase depending on the material thickness as well as the inside/outside dimensions.
Back stop system type 20, tapered (automatic):
- Thanks to the mounting of the back stop fingers on the continuous honeycomb profile, all back stop fingers can always be used when bending parallel, tapered or overlapped profiles. This ensures the highest levels of precision, even when narrow sheet strips are used.
- The maximum taper is +/- 250 mm across the entire bending length
- The servo drive and hardened stop edge on the stop finger ensure the highest levels of positioning accuracy of +/- 0.1 mm during busy working days and outstanding efficiency at a positioning speed of 366 mm/s.
Advantages
+ The automatic back stop cuts the preparation time to practically “zero”: in with the sheet and bend. Former "masterpieces” can easily be manufactured to the highest precision.
+ Once a profile has been drawn it can be retrieved for later orders and angles or shank lengths can be adjusted as required with a single click; the repeat precision is very high.
+ The simplest operating mode allows the machine to be used even without a graphic bending program and without a back stop.
+ Offline programming option: the machine is not “engaged” during programming but is 100% available for bending; it can be linked to a superposed software: profiles can be drawn on the building site or on the web by the customer and then sent directly to the machine.
+ The machine is not an expensive investment if one considers the advantages of the graphic control system and back stop.
Disadvantage
- More training is needed because the control system has more functions. Incidentally: anyone who can operate a mobile phone can handle the intuitive CP200 control system.
