Simotion D445 label die cutting precision

Rotoflex International of Ontario, Canada had been using electronic servo drives to control the reversing path movement of its Vericut label die cutting machines.

Simotion D445 increases label die cutting precision and reliability at Rotoflex Die Cutter Driven Forward Rotoflex International of Ontario, Canada had been using electronic servo drives to control the reversing path movement of its Vericut label die cutting machines.

But the technology had reached its limits.

After searching for a modular, expandable solution, the company selected the Siemens drive-based Simotion D motion control system with Sinamics drives.

Flexibility and performance, along with a speedy implementation, convinced Rotoflex managers to similarly equip future machine generations.

The atypical operation of the Vericut label die cutting unit is achieved through its design.

At its heart is a continuously turning magnetic roller with flexible die cutting plates, which are held in place only by magnetic force.

Depending on the label format, the magnetic plates wrap around the roller circumference at anywhere between 300 and 360 degrees.

This can result in a gap in the cutting pattern.

To prevent gaps, the label web motion is operated intermittently.

During each rotation of the magnetic roller, the substrate web briefly travels in the opposite direction to the production movement at precisely the right time.

At the end of the plate gap, it is resynchronized to the roller.

The reversing motion is controlled with an output cam.

The exact die cutting positions are recorded with sensors using registration marks on the web and transferred within a fraction of a second to the controller to correct any deviations.

Individually driven dancer rollers situated before and after the die cutting station decouple the reverse motion of the web in this area from the continuous motion of the line.

This requires a die cutter positioning accuracy of +/- 0.1millimeter (0.004 inches) at a maximum web speed of more than 90 meters/minute (295 feet/minute).

The most important component of the new high-performance solution is a Simotion D445 motion control system that integrates motion control, technology and PLC functionality in a compact Sinamics S120 drive system, permitting cycle times in the millisecond range without the usual interfaces.

The first Vericut machine equipped with the new technology includes nine servo-controlled axes.

A Simatic Multi Panel MP270 Touch is used for the operator control and monitoring of all the processes.

More axes possible The 18-axes limitation of the old control system was the primary reason for the conversion to the Simotion D445.

Additional axes would have required another controller.

Up to 64 drives can be connected the new Siemens motion controller, giving manufacturers the needed breathing space for future extensions.

Lines (also retrofits) can be augmented with additional modules, for example, for laminating and for lateral or cross cutting, thus quickly and economically satisfying specific customer requirements.

The modules can also be pre-configured in a standard controller software to cover all requirements, which can then be activated as required.

This greatly helps to simplify engineering as well as commissioning and software maintenance.

The relationship of the positions of the magnetic roller and the label web changes with the contact angle of the die plate.

It therefore has to be recalculated for each label format change.

The Simotion controller describes this relationship very precisely using a simple output cam comprising a linear and an exact sinusoidal component.

It reduces the time for the online calculation to a fraction of a millisecond.

The operator has practically no waiting time.

Thanks to the new smoother control and drive solution, downtime for format changes is further reduced, which provides significantly improved running and a die cutter positioning accuracy of +/- 0.05 millimeters (0.02 inches).

This gives manufacturers additional reserves.

Their machines not only cut labels more precisely, but also at higher web running speeds.

The use of standardized blocks developed by Siemens for a wide range of "converting" tasks also simplifies configuring, which provide all of the functionality required for the specific task of the used "winder" block, for example, various control modes such as dancer roller position control, tension control with torque limitation and speed correction or torque control (indirect tension control).

Also, the blocks are completely open.

This is a significant difference to the previous solution, and allows manufacturers to make changes themselves and to customize the functionality to specific needs.

The new motion control standard "Rotoflex wanted to present its modified machine at a trade exhibition".

"Thus, the conversion to the new control and drive concept needed to be completed in just over four weeks," as Stefan Muller, application developer at the Siemens converting industry group in Erlangen, explains.

"Thanks to the extensive cooperation between the machine manufacturer and Siemens application specialists from Canada and Germany, the project was successfully completed in time".

"And the upgraded label die cutter immediately found two customers at the exhibition!" This prompted the Canadian company to make the Simotion D and Sinamics combination its new standard for the second generation of Vericut lines currently being developed.

These machines with initially 22 axes already fulfill significantly higher demands.

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