COIL PROCESSING

Gentle treatment

CTL line enables flat and dimensional sheets to be fabricated in small batches with minimum set-up time
BY LUTZ-STEFAN HEINRICH, SCHNUTZ GmbH
S

ystems for the packaging of master coils, small coils, slit strips and sheets must meet differing requirements depending on the material. The finishing format as well as the number of pieces, size, thickness and possible coating also play a role. They may require, for example, particularly gentle handling of very sensitive surfaces, compliance with short set-up times or handling partial coils.

Fischer Stahl Warehouse
Each leveler installed at Fischer Stahl has a special tilt adjustment system that is able to compensate for various deformations in the material.
In order to supply customers with smaller batch sizes, Wolfgang Fischer Stahl GmbH, a German service center, installed a cut-to-length line as part of an expansion project in December 2020. The line allows the company to be flexible, producing flat and dimensional sheets in any number of pieces, regardless of the size of complete coils. The line can also process coated materials, even those with films to protect surfaces during transport and storage.

Fischer Stahl told its equipment supplier—Schnutz GmbH, a division of b+s group, that it was important to be able to offer small batch sizes processed from partial coils. Fischer chose the Schnutz line, in part, because it would be gentle in treating coated and pre-painted material surfaces. That is achieved with a special foiling system upstream and corresponding intermediate rollers within the leveling machines. A flying, high-precision slide shear also minimizes the cutting tolerance.

A flying, high-precision slide shear helps exceed customers’ cutting tolerances

A flying, high-precision slide shear helps exceed customers’ cutting tolerances.

The shear control makes it possible to maintain low shape tolerances of the sheets.

Decoil and rewind

At Fischer’s new CTL line, a coil lift truck feeds the decoiler with coils of up to 15 metric tons, which can be uncoiled from above or below. If there is an intermediate paper layer in the coil, it can be removed and disposed of using a corresponding rewinder. It’s possible to rewind coils that are only to be partially processed. The lift truck returns partial coils to inventory, where they are automatically weighed. Fischer Stahl can also assemble small batch sizes and knows exactly what quantities are being returned to the warehouse.
The line can process strips from 0.5 to 5.0 millimeters thick with the aid of two integrated levelers from Schnutz, arranged directly behind each other. The first leveler’s rollers have a 70-millimeter diameter and the second leveler’s rollers are 45 millimeters in diameter. Both sets of rollers are installed in a compact cassette that can be easily removed for maintenance.
The entire CTL line can be controlled from one main control panel
The entire CTL line can be controlled from one main control panel.
Eliminating defects
Each leveler installed at Fischer Stahl has a special tilt adjustment system that is able to compensate for various deformations in the material. The adjustment takes place along precisely manufactured curved sections that are characterized by their rigidity. This ensures that the upper and lower rollers are aligned over the entire infeed range.
In order to eliminate edge and center waves, the supports of the leveling rollers in both machines can also be individually adjusted vertically.

The b+s trimming shear offers a burr-free cut; the cutting gap is adjusted by axially moving the upper cutter shaft. The line can trim edges on both sides of the coil up to 30 millimeters. The trim scrap is shredded by a special scrap cutter, which can be adjusted to the different material thicknesses by means of an electromotive cutting air adjustment.

Cut blanks exit the shear.
Cut blanks exit the shear.
Surface integrity
In order to process coated and surface-sensitive coils without difficulty, a foil insertion device (in front of the two levelers) can foil the surface before leveling and protect the surface throughout the rest of the cutting process. Intermediate rollers support the integrity of the surfaces during the leveling process. Behind them is a flying carriage shear that does not require an additional looping pit.

The shear control, developed by b+s Automation GmbH, makes it possible to maintain low shape tolerances of the sheets at the specified belt speeds.

At the end of the line, a Burghardt+Schmidt swing-arm stacking machine ensures that sensitive material surfaces are treated gently through to the final processing steps. It features two stacking positions, which can also be used together for long sheets. All stops in the stacking area are moved electrically so that no damage to the belt edges occurs during destacking.

Central control
The entire CTL line can be controlled from one main control panel. There are screens on which all areas of the system can be viewed; in addition, two auxiliary control panels are available. The automation also has an interface to Level 3, enabling a fully automatic transfer of production data and an ability to preset the system to match the order parameters. The customer receives a report that its order has been processed.

When developing the system, b+s group felt it was important to be readily responsive to machine operators. Should problems ever arise, the automation built into the line provides b+s technicians full remote access to Fischer Stahl’s line for consultation and troubleshooting.

A special foiling system upstream and corresponding intermediate rollers in the levelers protect surface integrity
A special foiling system upstream and corresponding intermediate rollers in the levelers protect surface integrity.
Lutz-Stefan Heinrich is managing director of Schnutz GmbH, a division of b+s group. He holds a doctorate in engineering.
b+s group, Remchingen, Germany, b-s-germany.de.
Schnutz GmbH, Siegen, Germany, schnutz.com.
Wolfgang Fischer Stahl GmbH, Netphen, Germany, fischerstahl.de.
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