Tuesday, November 23, 2021

Z-Mill, Cluster or Sendzimir Mill

It is common for steel rolling mills to have backing rollers in a stand, but a Sendzimir mill has nine backing rollers on each side! This allows the working rolls to exert the pressure needed to cold roll harder metals such as stainless steel without bending the rolls.

"Washington Steel was the first U.S. company to use a Sendzimir Mill to cold-roll stainless steel." [wikipedia]

Of the three diagrams I have seen, this is the only one that doesn't have mistakes that are obvious to me. Note that the backing rolls at each level touch the rolls below but not each other.
Waterbury Farrel Brochure, p4

This diagram incorrectly shows the backing rolls touching each other, but it shows which rolls are driven and the two small work rolls. 
pinterest and LibraryOfManufacturing

The small work rolls allows the rolls to be made with stronger metals such as titanium because the smaller size is more affordable.

Waterbury Farrel Brochure, p4

The rolls are a small fraction of the unit. This is a reversible mill so that means the space between the work rolls (gauge) can be changed between each pass. I'm glad they opened the door to show the rolls in the photograph.
Waterbury Farrel Corp. Model Zr23-19

The work roll has a small diameter and the pass reduction rate is high, up to 60%. Some materials can be rolled into very thin strips without intermediate annealing.

Waterbury Farrel Brochure, p1

9:22 video   At 3:58 they show the rack moving. I assume that controls the gauge. But I have yet to figure out how that works.

And interesting summary of the mill types.

2:37 video

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