Aluminium rolling mill replaces cut-to-length line and leveler

Schnutz fitted quick-change leveling cassettes to speed up inspection and replacement of the leveling cassettes.

The new system satisfies the requirements defined by Martinrea Honsel Germany GmbH regarding evenness, operating speed and surface critical processing. It guarantees leveling quality according to DIN EN 485-4 and evenness according to DIN EN ISO 9445. Moreover, the new cut-to-length system ensures 97% availability.

“The range of products manufactured at our plant extends from coils and sheets to stamped blanks for trim parts in the automotive industry or sheet formed parts to decorate automobile interiors, to name just a few,” says Dipl.-Ing. Thomas Rünker, project manager at Martinrea Honsel. “The maintenance requirements for our previous system were rising continuously, and the procurement of spare parts was becoming increasingly difficult by the day.” It had become necessary to maintain the old system in painstaking, increasingly short intervals in order to continue ensuring high quality – and in emergencies it was even necessary to commission external providers with cut-to-length services. System availability was therefore no longer guaranteed.

“We had already collaborated with Burghardt + Schmidt GmbH in recent years on several projects which demonstrated their technical competency,” says Rünker. “Another decisive aspect for placing the order was the expertise at Schnutz GmbH, as their levelers had been picked as core components of the new cut-to-length system.” The Siegerland-based leveler machine specialist has supplied roll levelers since the early 20^th century and are therefore among the world’s oldest manufacturers in this field. In fact, Schnutz has built its first leveler in 1882. This experience was crucial to the production of a tailor-made system by Burghardt + Schmidt and its subsidiary Schnutz according to strict specifications.

Custom cut-to-length system guarantees evenness

Cold-rolled, wrought aluminium alloys are cut to length in the Martinrea Honsel plant in Meschede. These anodised and non-anodised aluminium strips are destined for the automotive, furniture and suitcase industries. A key requirement was the production of particularly even aluminium strips that guarantee trouble-free downstream processing. An unwinder is used to remove the strips from the coil and feed them into a leveler that uses 23 leveling rolls to ensure absolute evenness. Martinrea Honsel requires a working width of 300–1,250 mm, as well as a cut length of 300–3,500 mm. The strip thickness was between 0.3 and 2.2 mm. Moreover, the cut-to-length line needed to meet the length and form tolerances according to DIN EN 485 for aluminium and aluminium alloy strips, sheets and plates. The cut-to-length line is designed for up to 40 cuts per minute. “We manufacture those lines as a tailor-made solution in order to meet the conditions and specifications on site,” explains Thomas Baral, managing director at Burghardt + Schmidt GmbH. “The system only needs slight technical modifications to handle steel and stainless steel, as well as other metals.” Burghardt + Schmidt designs each system individually to meet the customer’s expectations and hence accommodates a broad application spectrum while still enhancing the quality of the results.

Quick change cassettes improve machine availability
“It’s our experience that the leveling unit defines the quality of each individual system,” says Rünker. “Good, reliable and regular maintenance of the leveling cassettes is essential to satisfy our requirements, as it is the only dependable uality and extremely short delivery times are guaranteed if the leveling cassettes need to be completely replaced.

Schnutz developed quick-change leveling cassettes so that inspection and replacement of the leveling cassettes can speeded-up. “These leveling cassettes improve accessibility and therefore the maintenance can be reduced,” says Baral. “During maintenance, the operator removes the cassette completely from the leveler and positions it on a rack which is enclosed on a robust welded steel frame. Lifting gear is then used to simply pick up the cassettes from there, inspect them, and then rework them if necessary.” This leads to minimal downtime and improved machine availability.

Drum shears accelerate operating process

Once it has been unwound and leveled, the strip is then cut crosswise into metal plates. “We equipped the system with a drum shear to speed up the operating process,” reports Baral. “Its advantage is that the material runs continuously and therefore a looping pit is not needed.” Not only does this make the system more compact, but it also reduces the cost of the footings. Setting the blade clearance for the drum shear is fully automatic. This means that the clearance between the two blades is adjusted automatically depending on the material strength and thickness. Material data are entered at the main operating console, and the drum shear adjusts to the right clearance. This prevents unnecessary user errors while also speeding up the operating process.

“The benefits of quick and individual adjustment for varying material properties are perfectly obvious,” Rünker explains. “It cuts tooling times and the cost of auxiliary process times, while also allowing quick intervention during production in case of any deviation from the customary quality standard. Corrections can be initiated immediately. It also significantly extends the life cycle of the cutting tools.” Additionally, the modern electronics in the drum shear and B+S’s proprietary software guarantee the narrow length tolerances requested by Martinrea Honsel.

Swing arm stacking machine protects the product surface

Once cut, the metal plates need to be stacked to ensure smooth downstream processing. But this can damage the surfaces if the plates are deposited improperly. “Our workpieces need to satisfy strict decorative standards, so an impeccable surface is essential,” explains Rünker. “This means they must not be scratched during stacking, and the edges have to be absolutely flush.”

This prompted Burghardt + Schmidt to equip the system with a swing arm machine to stack the sheets up to a height of 750 mm including pallet, without damaging their surfaces. The stacker has special swing arms with powered transport rollers in order to transport the sheets. Highly dynamic, three-phase servomotors with controlled force-velocity curve are used for the swivel and deposit movements. This ensures extremely precise swing movements. “In earlier iterations, these movements were powered pneumatically, but air is an extremely expensive medium,” says Baral to explain the motorization. “That’s why we now use energy-efficient servomotors.”

Punctual delivery enables quick commissioning

Each of the system’s manufacturing stages was completed on schedule, so Burghardt + Schmidt GmbH was able to deliver a turnkey cut-to-length system with protective fencing to Meschede as early as November. The system will be in the start-up phase until January. “Although we rescheduled the delivery date, Burghardt + Schmidt still helped us by ensuring punctual delivery and in doing so enabled quick replacement of the systems in our rolling mill,” says Rünker, looking back. “We are therefore confident that our customers will benefit from the improved quality of our new machine from January onward.”