Brückner's drive concept uses the latest technology of leading suppliers for high precision speed-control of the line. Profinet (Process Field Net), an industry technical standard for fast data communication over industrial Ethernet, ensures high speed and precision for control of the drive system.
There are specific drive solutions available for various components of a film stretching line in order to provide the best performance:
Direct Drives
Most accurate and reliable
Brückner is using its advanced direct drive system for rollers in the chill roll, machine direction orienter (MDO), transverse direction orienter (TDO), pull roll stand and winder. The motor is directly mounted to the roller's shaft with direct drives. That means no gears, no belts – and therefore no contamination from the belts’ wear, as well as low maintenance requirements.
Technology
Potential of increasing speed accuracy tenfold compared to conventional drive system
Excellent speed uniformity ensured by a sophisticated control system
Precise speed control to prevent film thickness variations in machine direction
Precise torque control leads to stable film tension, minimizing scratches, wrinkles and film breaks
General benefits of Direct Drives
Improved film quality due to better accuracy
Lower energy costs due to reduced energy consumption
Increased line availability due to lower maintenance
Reduction of spare parts due to elimination of gearboxes, belts and pulleys
Increased performance and lower noise level due to water-cooled design
Direct drive motors and flexible conical chucks to ensure precise and smooth film winding at highest speeds
No backlash due to elimination of gears
Clean mechanical assembly
High feedback resolution due to direct connection of encoder to roll for excellent repeatability
Active Tension Control (ATC)
High speed positioning with servo drives
Soft Drives
in the MDO preheating zone - a Brückner specialty
Soft drives for the MDO are nowadays standard in new Brückner film stretching lines. Brückner Servtec also installs them in existing lines in order to improve the film quality and productivity.
In the MDO all rolls are stiffy linked by the film. Any small speed difference creates high forces which can result in scratches on the film surface. The upgrade solution for older lines are soft drives which replace the stiff and inflexible belt / pulley drive with directly shaft mounted motors.
This allows easy tension setting in the pre-heating zone, flexible tension distribution along the pre-heating rolls and scratch free pre-heating in the MDO. Furthermore, since there are no longer belts and gear boxes, maintenance costs will be reduced due to less wear parts.