Manufacturing container or tube from paper; or other manufacturi – Bending – Folding
Patent
1997-05-12
1998-05-19
Hail, III, Joseph J.
Manufacturing container or tube from paper; or other manufacturi
Bending
Folding
493136, 493138, 493162, 493360, 493357, 493363, 493 72, B31F 700, B29C 6500
Patent
active
057529094
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a method of and apparatus for hemming an edge of sheet material.
BACKGROUND ART
In the field of liquid packaging it is known to employ as the packaging material a laminate consisting of, for example, paperboard coated on both faces with layers comprised of other substances, for example a barrier substance. The barrier substance may be a barrier to liquid, particularly water, such as PE, or barrier to oxygen, such as aluminium or EVOH. The two surface layers of the laminate are usually of a substance or substances such that the two layers can be heat-sealed together during forming of a liquid packaging carton. The cartons may be constructed from blanks individually cut from a web of the laminate. The cutting-out of the blanks leaves cut edges via which liquid or gas could penetrate into the paperboard and leak into or out of the carton, were it not for hemming of the cut edge, such as by skiving, i.e. milling-away, of a portion of the cut edge and folding-over of the edge zone and heat-and pressure-sealing of the folded-over edge zone to the remainder of the blank to cover the otherwise exposed paperboard with a barrier layer. Such hemming of the cut edge is disclosed in, for example, U.S. Pat. No. 3,654,842 and U.S. Pat. No. 5,236,408. A problem encountered with known hemming is that the folded-over edge zone tends to return to its original pre-folding condition, and so may not be completely and correctly heat-and pressure-sealed to the remainder of the blank.
DISCLOSURE OF INVENTION
According to one aspect of the present invention, there is provided a hemming method comprising forming, so as to extend along a free edge zone of sheet material comprised of a fluid-absorbent layer and a fluid-barrier layer thereon, a tongue upstanding substantially perpendicularly to a plane of said sheet material, a recess inwardly of said tongue, a land inwardly of said recess, and a groove inwardly of said land, folding-over said edge zone, inserting said tongue in said groove and sealing said edge zone to the remainder of the sheet material.
According to another aspect of the present invention, there is provided apparatus for hemming a free edge zone of sheet material comprised of a fluid-absorbent layer and a fluid-barrier layer thereon, characterized by forming means for forming a recess extending along said edge zone and spaced inwards of the free edge of said edge zone, thereby to leave a tongue extending along said edge zone outwards of said recess and for forming a groove extending along said edge zone and spaced inwards of said recess, thereby to leave a land extending along said edge zone outwards of said groove, folding means for folding-over said edge zone to cause said tongue to enter said groove, and sealing means for sealing said edge zone to the remainder of said sheet material.
Owing to the tongue-in-groove joint, the hemmed edge zone can be made more reliably fluid-proof. Moreover, the use of heat in the sealing can be dispensed with, and the seal be obtained purely mechanically by simply squeezing together the parts of the tongue-in-groove joint.
The sheet material can be in the form of a continuous web or an individual blank.
BRIEF DESCRIPTION OF DRAWINGS
In order that the invention may be more clearly understood and readily carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:
FIG. 1 shows a cross-section through an edge region of a cut-out blank of a liquid-packaging laminate of a first kind,
FIG. 2 is a view similar to FIG. 1, but with the edge region milled away to a desired profile,
FIG. 3 is a view similar to FIG. 1, but with the relevant edge zone folded-over and pressure-sealed to the remainder of the blank,
FIG. 4 is a view similar to FIG. 2, but of an edge region of a cut-out blank of a liquid-packaging laminate of a second kind,
FIG. 5 is a view similar to FIG. 3, but of the blank of FIG. 4,
FIG. 6 is a diagrammatic cross-section through a liquid packaging carton made from the blank of FI
REFERENCES:
patent: 3800677 (1974-04-01), Jones
patent: 4540391 (1985-09-01), Fries
patent: 4617211 (1986-10-01), Fries
patent: 4708708 (1987-11-01), Fries
patent: 4740163 (1988-04-01), Kuchenbecker
patent: 4757936 (1988-07-01), Homma
patent: 4927075 (1990-05-01), Lisiecki
patent: 4931031 (1990-06-01), Lisiecki
patent: 4979932 (1990-12-01), Burnside
patent: 5114392 (1992-05-01), McAdam
patent: 5207632 (1993-05-01), Brunlid
patent: 5236408 (1993-08-01), McAdam
patent: 5251809 (1993-10-01), Drummond
patent: 5385527 (1995-01-01), Fukada
Lyngaas Lars
Sagvik Ragnar Harald
Day Christopher W.
Elopak Systems AG
Hail III Joseph J.
LandOfFree
Hemming method and apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hemming method and apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hemming method and apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1848170