Method of manufacturing sheets being able to tear off
US7175731B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 18, 2002 |
| Grant date | Feb 13, 2007 |
| Priority date | — |
| Expiry date | Apr 18, 2022 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/15
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
The present invention relates to a method of manufacturing tearable sheets, wherewith each sheet obtains a perfectly smooth tear edge when torn-off. The method comprises the steps of: punching each sheet transversely of the fibers of said sheet from a first side of the sheet to an extend corresponding to a firs portion of the thickness of the sheet; and punching each sheet transversely of the fibers of said sheet from a second side of the sheet to an extent corresponding to a second portion of the thickness of said sheet; wherein the sum of said first thickness portion and said second thickness portion is smaller than the thickness of the sheet, and wherein the second punching operation is performed parallel with the first punching operation but displaced in a plane parallel with said first and said second sides of the sheet, said displacement being adapted for tear-off purposes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.