Manufacturing container or tube from paper; or other manufacturi – Container making – Pliable container
Reexamination Certificate
1998-11-19
2002-07-23
Smith, Scott A. (Department: 3721)
Manufacturing container or tube from paper; or other manufacturi
Container making
Pliable container
C493S213000, C493S394000, C493S209000
Reexamination Certificate
active
06422987
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a possible way of producing recloseable bags. The bags may be flat bags or folded bottom bags. These bags, which are produced, for example, from a film material and are to be filled with foodstuffs, can be reclosed by means of a so-called recloseable strip provided in the top region of the bag walls. One half of said recloseable strip is firmly welded in one bag wall and the other half is firmly welded in the other bag wall. When the two halves, and thus the two bag walls, are pressed together, the two halves of the recloseable strip interengage so as to form a closure for the bag. The recloseable strip can be opened by the two bag walls being drawn apart from one another, that is to say the two halves of the recloseable strip are released from one another.
2. Brief Description of the Background of the Invention Including Prior Art
Flat bags and folded bottom bags may be produced from weldable plastic-web material. The recloseable strip is usually made of plastic. In order, then, to seal permanently the crossover region of the recloseable strip with the longitudinal sealed seams of the bag, a very large amount of heat energy has to be introduced there. This is also necessary as a result of the cross-sectionally bulky form of the two halves of the recloseable strip, these halves having to be welded in a liquid-tight manner to these longitudinal sealed seams. When the recloseable strip is opened, its two halves remain closed in the region of the longitudinal sealed seams, in order to prevent any leakage there.
The introduction of the heat energy which is required in these end regions of the recloseable strip takes a relatively long time. This means that the bag which is to be produced has to reside in this sealing station for a corresponding length of time. This impairs the performance.
In order to enhance the performance, the number of sealing stations may be increased. This makes it possible for heat to be introduced into this crossover region a number of times, on a progressive basis. The crossover region of the recloseable strip and sealed seams is sealed a number of times from the outside of the bag, and this introduces sufficient heat to the inside of the bag wall and thus into the region of the recloseable strip. As a result, the recloseable strip can be pressed flat and welded into the sealed seam. Since it involves more than more sealing station, this production process results in corresponding additional costs. A correspondingly large amount of space is also required. It is also disadvantageous that, as the number of sealing stations increases, there is also a corresponding increase in the number of reject bags when production is interrupted, since cooling of the sealed seam before it is finished off at the last sealing station renders the sealed seam incomplete. Since it is not possible to finish off the sealing operation subsequently, the bag cannot be used.
It is known to reduce the quantity of heat required in the crossover region by virtue of some of the materials which are to be welded being punched out in the crossover region. Thus, it is known to punch out part of the recloseable strip in the crossover region. This has great disadvantages if format adjustment is necessary. This is because it is very difficult and technically complex to perform the punching-out operations precisely at the desired location in each case; an excessively large punched-out section would result in leakages and an excessively small punched-out section would reduce the desired effect.
Also to be taken into account in all the above-mentioned production variants is the fact, which is fairly problematic from the technical point of view, that, when being drawn off from a roll on which it has been wound up, the recloseable strip expands to different extents. This means that it is barely possible, with the desired amount of precision, to introduce the recloseable strip precisely into the bag region where it is to be fastened on the bag walls.
SUMMARY OF THE INVENTION
1. Purposes of the Invention
The object of the invention is to specify an improved way of producing a recloseable bag by means of a recloseable strip.
These and other objects and advantages of the present invention will be come evident from the description which follows.
2. Brief Description of the Invention
This invention is realized, for an apparatus for producing recloseable bags by means of a recloseable strip. Two outer sealing jaws are disposed in a crossover region of a longitudinal sealed seam and of a recloseable strip for introducing heat through two bag walls of a bag from the outside for welding the bag walls to the recloseable strip. in a region of the longitudinal sealed seam. An inner sealing jaw is positionable between the two bag walls in the crossover region of the longitudinal sealed seam and of the recloseable strip. A counter-jaw is furnished on an outside of a bag wall, said counter-jaw being located opposite to said inner sealing jaw, such that the bag wall is positionable between the inner sealing jaw and the counter-jaw by way of a crossover region of the bag wall for pressing a relevant half-of a recloseable strip flat and for welding the relevant half of the recloseable strip to the bag wall. A recloseable opening of said bags is surrounded by halves of the recloseable strip. These mutually opposite halves are firmly welded to mutually opposite bag walls. These mutually opposite halves are welded at their ends to two lateral longitudinal sealed seams of the bag.
Rather than the heat being introduced just from the outside, that is to say by way of outer sealing jaws at least in the crossover region of the recloseable strip and longitudinal sealed seam, the invention provides that, in this crossover region, heat is also introduced from the inner region of the bag into the crossover region, and thus directly to the recloseable strip. In the case of the apparatus according to the invention, an inner sealing jaw will be positioned between the two bag walls in the crossover region of the longitudinal sealed seam and recloseable strip. This sealing jaw corresponds with counter-jaws positioned on the outside of the bag walls. The action of pressing the two counter-jaws together against the inner sealing jaw thus makes it possible to press flat the two halves of the recloseable strip and weld the same to the respective bag wall.
In order to avoid constraining forces when the counter-jaws are pressed together, the sealing jaw, which is positioned between the counter-jaws, is preferably mounted in a floating manner.
It is preferable for the two counter-jaws likewise to be heatable and thus to be designed as sealing jaws. This means that, rather than just acting on the recloseable strip and the bag walls from the outside, the heat can also act on these from the inside, and thus from both sides.
According to one advantageous embodiment of the apparatus according to the invention, this apparatus is distinguished by three sealing stations, through which the film web from which the bag is produced passes one after the other. In the first sealing station, the two halves of the recloseable strip are welded to the respective bag wall. For this purpose, the recloseable strip is in the closed state. This means that the two halves of the recloseable strip closely interengage. The welding takes place such that, in the region of the interengaging cross-sectional regions of the two halves of the recloseable strip, there is as little heat as possible in the region of the outer walls. The second sealing station has the two outer counter-jaws and the inner sealing jaw. Activation of the two counter-jaws and of the inner sealing jaw allows the recloseable strip, which is open in this station, to be pressed flat and in each case one half of the recloseable strip to be welded to the relevant bag wall by way of its pressed-flat region. In the third sealing station, the outer sealing jaws provided there produce the complete longitudinal sealed seam, that is
Darby & Darby
Harro Hofliger Verpackungsmachinen GmbH
Smith Scott A.
Tawfik Sameh
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