Theory of Operations
Rovema VPK Operators Manual
3/2000 VPK REV(B) PANELVIEW 600
4-5
Vertical Sealing Cycle
The vertical sealing cycle starts just before the film starts moving. The
vertical sealing device is timed to engage the film tube a few milliseconds
before the film feeding device begins advancing film. This allows
sufficient sealing time for the film position in front of the sealing band.
When the device engages the film, it presses the rotating sealing band
against the overlapping sections of film. Because the band and the film
move at the same rate, the band is always stationary with respect to the
film. This prevents the vertical sealing device from wrinkling the film.
When the film stops moving, the seal band stops and remains extended
for a few milliseconds, then it retracts.