PositionServo Simplifies Corrugated Board Printing

Lenze Americas 3/7/2018

Lenze 940 PositionServoLenze Americas PositionServo drives, servomotors and smd Series AC inverter drives have all been utilized in the latest generation, specialty printing machine for corrugated board.

Cardboard material is auto-fed into the printing machine at high speed and passed through five sets of rollers positioned above and below the board.

The rollers at the top deposit the printing ink, one color at a time. The lower set of rollers control the pressure exerted on the material as it is passed through the printing process.

The thickness of the material ranges from 1 to 3mm for solid board and 1.3 to 8mm for corrugated board, for both types of card the position of the roller is critical to the print finish and smooth throughput.

Four PositionServo Lenze servo drives and servo motors are used. The first two drop the roller's position and allow a new sheet to be fed in; the second pair is used for fine control while the machine is actually printing.

The PositionServo's 64-bit processing and two microsecond reaction time allow tiny, fast incremental position changes during printing. This creates a displacement effect, compressing the card as it passes through, creating smooth surface finishes, ironing out any material inconsistencies in the raw board, and ensuring a consistent print finish.

The entire process is PLC controlled and high-resolution linear encoders supply positional feedback; hence the servos have a simple, but high accuracy task to perform. Lenze Americas SMD 15kW AC inverter drives are also used to control the drying fans that make sure the ink is fixed after the application of each print color.

Sometimes the amount of energy that must be dissipated using dynamic braking is too much for the DB circuit. Lenze-AC Tech Dynamic Braking circuits are primarily light-duty and not intended for long on-times. In this case, using a separate line regeneration module is recommended. The line regeneration module is tied between the 3-phase input side of the drive and the DC bus terminals. It is used for regeneration control of any AC drive system that uses a fixed DC bus system. This unit provides for regulation of the bus and prevents the drive from tripping on overvoltage. Regeneration modules are available from companies like Bonitron.

PositionServo Benefits:

  • Tight positioning control
  • Linear encoder compatibilty
  • Simple set-up and programming
  • Global sales and technical support
  • Lenze Americas, one source for servo drives, servo motors and VFDs