Vertical flow wrapper

Vertical fill and seal machines are used for packaging products into bags. The bag material comes from a plastic film coil that is first unwound, then shaped into a tube by a mechanical mandrel. At the same time the tube is sealed vertically.

The feeder movement is intermittent and the feed length corresponds with the bag length. Once fed through, the bag is horizontally sealed so it can be filled with the product. After that, the process starts again by feeding a new bag.

Main function

Feeder: A bag foil is fed via a loop control to the filling station. The foil tension control is achieved with a dancing arm system and an inverter.
Register: Because the foil feed is subject to slippage, the exact position of the foil is constantly monitored using a registration mark encoder.
Driver: Two vacuum side belts controlled by two servomotors pull the film through the forming area.
Former & side-sealer: A forming collar is used to shape the film into a bag, and the length is sealed by the longitudinal sealing unit.
Bottom-sealer & filler: After the bag is sealed at the bottom, the filling station drops product into the bag.
Top-sealer: Once the bag has moved downward by one length, a transverse sealing unit closes the bag and a cutter separates the packaged product from the bag foil.

Automation architecture

Simple PLC‐Based motion control

This solution is the perfect fit for vertical flow wrappers with intermittent servo-driven sealing jaw. Since axis synchronization is not required, the machine sequences (Unwind, Mark Register, Form, Fill & Seal) can be programmed into the CJ2‐Series PLC thanks to the advanced function blocks of the CX‐One library (PLC/HMI/Drive programming environment).

Cost‐effective daisy chain wiring method with PTO signal inversion

The use of junction blocks allows to reverse the PTO signal from one servo drive compare to the other. This wiring method makes turn one servo‐motor clock‐wise while the other turn counter clock wise in a perfect synchronization. This configuration enables the two servo‐drives to run in synchronization without the need for advanced motion controller.

Easy positioning control with Pulse Train Output (PTO)

This configuration uses only one CJ2‐Series Pulse Output unit (CJ2M‐MD212) with two pulse train outputs to command three servo‐drives. The first output is used to command the unique servo‐drive of the sealing system. The second output is used to command, through junction blocks, two G5‐Series servo‐drives which control the foil vacuum pull‐belt.

Dedicated interrupt feeding control

The foil/bag positioning before sealing is achieved with a simple interrupt feeding function block which processes the registration mark detection (E3U‐GL) via an interrupt input which is used as trigger during speed control to switch to position control and then move a specified amount, equivalent to one bag length, before decelerating to a stop. This architecture keeps the solution cost-effective, pneumatic‐system free and really reliable in regard of the required performance.