Drives Improved film quality

Innovative Drive Solutions

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

 

Where to install direct drives

at a biaxial film stretching line

  • Better speed accuracy (tenfold)
  • Better uniformity of cast film (MD tolerances)
  • Higher stiffness
  • Better control of dynamics
  • Excellent speed stability which grants best thickness uniformity
  • Direct Drives for stretching / annealing zone and tension isolation
  • Soft drives for pre-heating section; each roll is adjusted to the thermal expansion of the film (more details below)
  • Less space required
  • Special design with hollow shaft for easy supply of cooling water or thermal oil for rolls
  • Direct drives at TDO inlet
    • No gears
    • Reduced lubrication and maintenance
    • High precision
    • Reduction of chain load
    • Reduction of track temperature
  • Direct drives at TDO outlet
    • Elimination of gear box
    • Better synchronization of both chain drives
    • More operation data available
  • High torque direct drive with Active Tension Control (ATC) software
  • No hazardous belts, no wear
  • Clean and efficient due to water cooling
  • Individually controllable roll speeds
  • Stable film tension under changing process conditions
  • Less wrinkles, scratches and film breaks
  • 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.

Benefits of MDO Soft Drives

  • Scratch-free preheating in MDO
  • Easy operating - only two parameters are needed
  • No wear, no belts or gear boxes
Soft drives are adjustable to various film types