Tube mill rolls are the working surfaces of the mill: every pass that turns strip into pipe is a pair of rolls, and every mark, ovality or weld defect can be traced back to one of them. We machine rolls for breakdown, forming, fin, welding and sizing passes, in sets matched to the pass line you run.
Rolls We Make
- Forming and breakdown rolls for the first passes, where strip is folded without surface marking.
- Fin and squeeze rolls that set the weld V and hold the edges at the weld point.
- Sizing, shaping and Turk's head rolls for the final diameter and roundness.
- Replacement rolls for existing mills, machined to sample or drawing.
Rolls are turned and milled on CNC machines, hardened and vacuum heat-treated in our own furnace, then finished and checked before packing. Send the tube size, wall and mill model and we will confirm the pass and the profile.
What each roll pass has to do
A roll set is not twelve identical parts. Each pass has a job, and the profile is cut for that job:
| Pass group | Job | Typical failure if the profile is wrong |
|---|---|---|
| Breakdown | Start the bend without marking the strip surface | Surface scratches, edge ripple |
| Forming | Distribute the bend until the strip is almost closed | Edge wave, twist, over-thick corners |
| Fin / weld | Present the two edges parallel at the weld point | Cold weld, heavy bead, seam notch |
| Sizing | Correct OD, ovality and roundness after welding | Oval tube, inconsistent OD along the coil |
Replacing rolls on a mill we did not build
Most roll enquiries we receive are for existing mills, often imported second-hand. We work from a worn sample, a drawing, or measured profiles taken off the stand. The important information is the stand number, the tube size that stand was running, and whether the mill has been re-shimmed since the rolls were made — a roll copied from a worn sample without allowing for wear reproduces the wear.
Where the original drawing exists, we machine to the drawing; where it does not, we measure the profile, reconstruct the pass and confirm it with you before cutting metal.
Hardness and regrinding allowance
Forming and sizing rolls are normally supplied in the 58–62 HRC range, with the working surface uniform within about ±1.5 HRC. If you plan to regrind, say so at enquiry stage: we leave additional stock on the groove so the profile survives two to four regrinds rather than one.
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