Z-High® Mills

Sendzimir Z-High® Mills were developed to combine the advantages of the Sendzimir cluster-type rolling mill with those of the 4-High. After several attempts, the Z-High® configuration, and the ability to retrofit the 4-High mill with a Z-High® insert, was born.

The Z-High® concept permits the revamping of a classical 4-High mill with a system that uses a much smaller work roll. This new configuration allows the mill to take heavier reductions per pass and achieve thinner gauges. Harder materials can be rolled without intermediate anneals, and a better surface can be produced. Moreover, intermediate rolls are equipped with axial shifting displacement and, are ground with parabolic (or straight) tapers at their ends, so that the mill can change "effective flat" and provide excellent shape control possibilities.

Normally, the conversion of a 4-High to a Z-High® requires no other electrical changes, except to reverse the leads to the main mill motor so that it will rotate in the opposite direction. However, other improvements can be incorporated, including screwdown, winder mandrel upgrades, higher tension, and if necessary, a change in mill lubrication and strip wiping.

Z-High® Mill Installation Configuration Possibilities

• As a retrofit into an existing 4-High mill, whereupon the "Z-High® Package" is adapted to an operating mill where the mill can be reconverted into a 4-High by withdrawing the "Z-High® Insert" and replacing the 4-High work rolls, chocks and drive spindles.
• As a conversion of a 4-High mill to a "dedicated" Z-High® mill and optionally widening the mill at the same time.
• As a new Z-High® / 4-High convertible mill similar to (1) above and built according to new mill specifications (sometimes referred to as the "midget mill").
• As a new Z-High® mill with smaller diameter back-up rolls, smaller chocks and smaller mill housings, as compared to 4-High mill of the same width.
• As a tandem mill either in a process line, in line with the other process line equipment, or, in a stand-alone single pass tandem mill configuration.

The versatility in installation configuration of a Z-High® results in a smaller capital investment than other alternatives.

The "hot" Z-High® Mill

Sendzimir's Z-High® Mill is particularly suitable for "hot" situations such as the exit section of a thin slab continuous caster.

The lightweight, chockless work roll can be exchanged in under a minute with strip in the mill, thus ensuring virtually nonstop performance in a continuous production situation.

Process Line Z-High®

Modifications were made to the Z-High® Mill to make it compatible with operating conditions within the continuous casting environment.

The size of the work roll is small enough to allow high specific pressure for thinner gauges yet large enough to give a sizeable draft reduction on heavy-gauge materials without skidding. Reductions in stainless steel of up to 35% per stand have been documented.

The lightweight, chockless work roll can be exchanged in under a minute with strip in the mill, thus ensuring virtually nonstop performance in a continuous production situation.

Sendzimir's Z-High® Mill is the only design capable of reducing incoming stainless steel strip hot band to cold-roll gauges in a single pass (in a process line).

With the Process-Line Z-High® Mill, whether in single or multiple stands no upstream equipment is required other than superficial surface cleaning brushes and like equipment.

Company engineers foresee high-value-added, thin-gage strip of very high surface quality and strip profile being produced continuously and directly from a continuous thin-strip caster. Coils of indefinite length will be possible, since the entire system will be capable of synchronization. Sendzimir officials predict that when stainless steels are strip cast, the Process-Line Z-High® mill will be essential, because it will be the only mill capable of reducing and finishing such hot-rolled material directly to thin gages in an in-line process.

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