US 12,330,364 B2
Device and process to permit monoaxial changes in the length of film webs
Bernd Bayer, Bobingen (DE)
Assigned to HOSOKAWA ALPINE Aktiengesellschaft, Augsburg (DE)
Filed by HOSOKAWA ALPINE Aktiengesellschaft, Augsburg (DE)
Filed on Jan. 19, 2021, as Appl. No. 17/151,814.
Claims priority of application No. 10 2020 000 334.6 (DE), filed on Jan. 21, 2020.
Prior Publication US 2021/0221043 A1, Jul. 22, 2021
Int. Cl. B29C 55/06 (2006.01); B29C 55/28 (2006.01)
CPC B29C 55/06 (2013.01) [B29C 55/28 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A device for permitting a monoaxial length change of a film web in a machine direction, the device comprising:
a processing gap delimited by a first and a second roll via which the film web is routed in the machine direction, the first roll in a film transport direction being upstream of the processing gap and being configured to operate at a first peripheral speed, and the second roll in the film transport direction being downstream of the processing gap and being configured to operate at a second peripheral speed such that the film web that is routed through the processing gap experiences monoaxial length change,
wherein the first roll is an air-flow roll through which air can flow,
the second roll is also an air-flow roll through which air can flow,
at least one of the first roll and the second roll is a combined tempering and air-flow roll through which air can flow, the combined tempering and air-flow roll being formed as a double-jacket roll having channels for air flow,
the device further comprises a negative pressure source connected to the second roll that is downstream of the processing gap, the negative pressure source being configured to apply a negative pressure to the second roll such that air from outside flows through the second roll into an inside of the second roll so as to generate suction where the film web is routed over the second roll, and the second roll being configured such that the suction generated by the negative pressure sucks the film web onto the second roll during the monoaxial length change so as to reduce transverse neck-in and edge build-up, and
the negative pressure source is further configured for applying different degrees of negative pressure along a length of the second roll, the negative pressure source applying more suction at the edges of the film web than towards the center of the film web.