US 12,123,700 B2
Methods and systems for blown film thickness measurement
Thomas J. Strey, River Falls, WI (US); David L. Hofeldt, Oakdale, MN (US); Gregory J. McGill, Maplewood, MN (US); Jay M. Krieger, Eau Claire, WI (US); Christopher J. Rother, St. Paul, MN (US); and Paul C. Thomas, Hudson, WI (US)
Assigned to 3M Innovative Properties Company, St. Paul, MN (US)
Appl. No. 17/765,873
Filed by 3M INNOVATIVE PROPERTIES COMPANY, St. Paul, MN (US)
PCT Filed Sep. 24, 2020, PCT No. PCT/IB2020/058929
§ 371(c)(1), (2) Date Apr. 1, 2022,
PCT Pub. No. WO2021/069997, PCT Pub. Date Apr. 15, 2021.
Claims priority of provisional application 62/913,496, filed on Oct. 10, 2019.
Prior Publication US 2022/0412723 A1, Dec. 29, 2022
Int. Cl. G01B 11/06 (2006.01); B29C 48/10 (2019.01); B29C 48/92 (2019.01); B29C 48/88 (2019.01); B29C 48/885 (2019.01)
CPC G01B 11/06 (2013.01) [B29C 48/10 (2019.02); B29C 48/92 (2019.02); B29C 48/885 (2019.02); B29C 48/913 (2019.02); B29C 2948/92152 (2019.02); B29C 2948/92428 (2019.02); B29C 2948/92647 (2019.02)] 13 Claims
OG exemplary drawing
 
1. A sensing system for online measurement of a blown film comprising:
a terahertz (THz) sensor positioned adjacent to a film bubble extruded from a blown film die; and
a sensor support configured to guide the THz sensor around the circumference of the film bubble, wherein the THz sensor is configured to:
measure a thickness profile of the film bubble;
measure a thickness of a doubled film which is formed by collapsing the film bubble; and
compare the thickness of the doubled film with the film thickness profile of the film bubble.
 
10. A method of online measurement of a blown film comprising:
providing a terahertz (THz) sensor positioned adjacent to a film bubble extruded from a blown film die;
guiding, via a sensor support, the THz sensor around the circumference of the film bubble;
measuring, via the THz sensor, a thickness profile of the film bubble;
measuring, via the THz sensor, a thickness of a doubled film which is formed by collapsing the film bubble; and
comparing the thickness of the doubled film with the film thickness profile of the film bubble.