Know-how (part 2)
Technology . Mandrel bending machine in practice: The right setting
You know the wide-ranging capabilities of a mandrel bending machine from the first part of the digression. This time, you learn how to recognise and correct errors in practical application – for optimal results.
Error analysis and remedy
1. Pipe breaks off
- The material does not have the correct elastic limits and forming qualities. Non-annealed pipe quality.
- Acquire a different material or possibly heat non-iron metal pipes in order to appropriately adapt the qualities.
2. Pipe slips in clamping section of the bending tool
- Adjust the pressure on the clamping section.
- The clamping section must be roughened, eroded or equipped with a sawtooth.
- The clamping section must be longer.
- On the initial bending a solid adapter can be pushed into the pipe end.
- Too much pressure on the clamping section; the mandrel elements are clamped too hard. Air gap on the flanks too large; pressure too high.
- Too much pressure on the pressure die; excessive counterforce to the wiper die is generated.
- The mandrel is too far forward; readjust the mandrel behind the tangent.
- Too few links on the mandrel; the pipe already catches in the clamping section at a low angular degree.
3. If only folds arise, it may be due to the following:
- Mandrel and/or wiper die not in correct position.
- Mandrel diameter too low in relation to the radius and the wall thickness.
- If folds form, this can be caused by using the wrong mandrel section.This is especially the case when the folds form towards the inside of the bend area. Then a mandrel with smaller distances between the segments must be used (open pitch, closed pitch, ultra closed pitch). Use a mandrel with closely positioned segments.
- Nicht ausreichende Schmierung oder falscher Schmierstoff oder Schmierung an falscher Stelle.
- Dorn steht zu weit hinten, hinter der Tangente der Biegerolle.
- Insufficient lubrication or incorrect lubricant or lubrication in the wrong place.
- Mandrel too far to the rear, behind the tangent of the bending roll.
- Wiper die not in the correct position.
- Wiper die worn out.
- Outside pipe diameter and tool are not precisely matched.
- The flanks of the pressure die touch the flanks of the roller when closed.
- Insufficient pressure on the pressure die.
- Excessive lubrication.
The third and final part of our technology report for mandrel bending machines can be read in the upcoming edition of t time(s).