Film stretching. The U.S. Patent and Trademark Office awarded a patent to Siegsdorf, Germany-based, Brückner Maschinenbau GmbH & Co. KG for a machine that stretches plastic film in both the transverse and longitudinal directions. According to the patent, the invention does not tear the film during stretching and avoids problems with the film’s appearance that can occur with previous equipment.
The machine includes two tracks, each of which has a first rail on which clips for holding the film move, and a second rail on which articulated carriages move. The machine also has a mechanism featuring toothed indexing wheels for adjusting the pitch of the clips.
“The pitch of the clips changes and over time there is a fluctuation in the stretching angle, resulting in a change in the visual properties of the film and occasionally its tearing,” the patent states. “By means of a mechanism for indexing the pitch adjusting point of the clips, said detrimental effects are fully corrected.”
Patent 10,486,360; issued Nov. 26