Coiling extruded plastic pipe

[robnew]

We are a manufacturer of extruded plastic tubing and pipe. We have recently added a coiler that allows us to wind small diameter pipe and tubing onto a coil for shipping long lengths. I need to be able to predict the success we will have coiling a product before we try it. I can think of several failure modes: 1) breaking (presumably when the tensile strength is exceeded) 2) kinking (probably buckling of the wall of the tube against the coiler) 3) Collapsing of the diameter of the tube. 4) Stress relaxation causing the tube cross section to not be round and the tube to not be straight.

I'm looking for any insight into predicting these coiling failures, especially the first 3. Also, any insight into other potential problems.
Thank you,

 

[griffengm]

On your coiler there should be a device we called a "dancer arm". The arm is linked to a potentiometer governing the speed of the uptake and thereby controlling the tension on the extrusion. As the tension increases a predetermined loop would pull up and raises the arm which in turn slows the take-up.
Controlling the tension addresses all of the failure modes you listed but assumes that you have controlled the set prior to coiling. If you don't control before coiling then the weight of the tube will cause it to continue to deform after it leaves your immediate control area.

Griffy