Package making – Methods – Enclosing contents within progressively formed web means
Reexamination Certificate
2001-03-07
2004-05-04
Rada, Rinaldi I. (Department: 3721)
Package making
Methods
Enclosing contents within progressively formed web means
C053S550000, C053S552000
Reexamination Certificate
active
06729108
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing flexible bags and to a vertical type forming, filling and sealing machine for manufacturing the flexible bags from long lengths of film.
2. Description of the Related Art
Conventionally, vertical type forming, filling and sealing machines have been used for putting contents in the form of liquid or paste into bags.
The vertical type forming, filling and sealing machine generally comprises a bag forming guide for forming long lengths of film into tubular shapes, a vertical sealing mechanism for heat sealing mating surfaces at edges of the film formed into tubular shapes along the longitudinal direction of the film to form tubular film, and a horizontal sealing mechanism for heat sealing the tubular film over its entire width. Each of the vertical sealing mechanism and the horizontal sealing mechanism includes a heater bar and a heater receiving bar opposite to each other such that they press and heat the film at the same time to heat seal the opposing inner surfaces of the film.
Contents are supplied into the film below the vertical sealing mechanism and above the horizontal sealing mechanism. While the film is intermittently fed at constant pace, the vertical sealing mechanism heat seals and forms the film into tubular shapes, the contents are supplied thereinto, and then the horizontal sealing mechanism heat seals the film in the width direction, thereby manufacturing flexible bags having the contents enclosed therein.
The flexible bags are successively manufactured in the vertical type forming, filling and sealing machine. Thus, after the horizontal sealing mechanism heat seals the film, the film is cut at the point of the heat sealing in the width direction for division into each bag.
To achieve highly constant amounts of the contents, or to prevent rottenness of the contents due to air present in the flexible bag, the contents may be supplied into the tubular film to a position above the horizontal sealing mechanism and then separated by nipping from the outside the tubular film in which the contents are enclosed.
Especially when the contents are in the form of paste, a pair of squeezing rollers for nipping film from the sides is provided as a mechanism for dividing such contents. The contents in paste form are supplied to a position above the squeezing rollers, and then separated by closing the squeezing rollers. The squeezing rollers in the closed state are rotated to feed the film downward, and a no-filling portion is formed in the area of the film nipped and fed by the squeezing rollers. The no-filling portion is heat sealed by the horizontal sealing mechanism. In this manner, the heat sealing of the film by the horizontal sealing mechanism is favorably performed even for the contents in paste form.
FIGS. 1
to
3
show representative examples of packing with film.
FIG. 1
shows pillow type flexible bag
500
. The aforementioned forming, filling and sealing machine is generally used to manufacture pillow type flexible bag
500
. Flexible bag
500
includes vertical seal portion
501
which is the portion heat sealed by the vertical sealing mechanism and horizontal seal portions
502
which are the portions heat sealed by the horizontal sealing mechanism.
It is possible to manufacture three-side seal type flexible bag
510
as shown in
FIG. 2
by changing the orientation of the horizontal sealing mechanism with respect to the vertical sealing mechanism in the aforementioned forming, filling and sealing machine. Flexible bag
510
also includes vertical seal portion
511
which is the portion heat sealed by the vertical sealing mechanism and horizontal seal portions
512
which are the portions heat sealed by the horizontal sealing mechanism.
In addition, it is possible to manufacture four-side seal type flexible bag
520
as shown in
FIG. 3
by providing a second vertical sealing mechanism for the aforementioned forming, filling and sealing machine at the position opposite to the vertical sealing mechanism with the film interposed between them for heat sealing the fold of the film along its longitudinal direction. Flexible bag
520
includes vertical seal portion
523
which is the portion heat sealed by the second vertical sealing mechanism in addition to vertical seal portion
521
and horizontal seal portions
522
similarly to three-side seal type flexible bag
510
shown in FIG.
2
.
On the other hand, another form of flexible bags is freestanding bags. Since the freestanding bags such as plastic cases, cans or bottles, can be placed upright on the storefront and fold compact for disposal after the contents thereof are consumed, they have come into widespread use as a packing form replacing the aforementioned ones.
Various forming machines have been proposed to manufacture such freestanding bags, and particularly, Japanese Patent Laid-open Publication No. 11-152104 discloses an apparatus which is an application of the aforementioned vertical type forming, filling and sealing machine. Specifically, the disclosed apparatus has a folding mechanism for folding inward a fold of film at the position opposite to a vertical sealing mechanism with the film interposed between them, and a bottom sealing mechanism for heat sealing two projections of the film formed by folding the film by the folding mechanism to form the bottom of a freestanding bag, added to a forming, filling and sealing machine for manufacturing the aforementioned three-side seal type flexible bag. The forming, filling and sealing machine manufactures freestanding bags in a laid state.
FIG. 4
shows an example of a freestanding bag manufactured by the forming, filling and sealing machine disclosed in Japanese Patent Laid-open Publication No. 11-152104. As shown in
FIG. 4
, freestanding bag
550
includes two side seal portions
552
, top seal portion
551
, and bottom seal portion
553
. Side seal portions
552
are formed by a horizontal sealing mechanism, top seal portion
551
is formed by the vertical sealing mechanism, and bottom seal portion
553
is formed by the bottom sealing mechanism.
In this manner, the vertical sealing mechanism can be combined with the horizontal sealing mechanism as appropriate to manufacture various forms of flexible bags by using long lengths of film.
In the aforementioned conventional forming, filling and sealing machine, the horizontal sealing mechanism presses and heat seals film with the heater bar and the heater receiving bar as described above. It is necessary to use a heater bar and a heater receiving bar longer than the width of flexible bags to reliably perform heat sealing of the film over the entire width. Flexible bags have various sizes ranging from several centimeters to several tens of centimeters of width depending on the types of contents and the uses of the flexible bags.
As the width of film is greater, the heater bar and the heater receiving bar necessarily press the film in a larger area. An increase in the pressed area of the film means that actual pressure per area applied to the film is reduced as long as the film is subject to the same pressure. As a result, sufficient seal strength cannot be obtained. This is true generally of horizontal seal in the vertical type forming, filling and sealing machine regardless of the form of flexible bags.
Especially when the pillow type flexible bags or freestanding bags are manufactured, film is folded different times in the area of the film heat sealed by the horizontal sealing mechanism. Consequently, a difference in height occurs in the film at the boundary between different thicknesses of the film. The difference in height as well as heat heat sealability or flexibility of the film may cause defective seal at the time of heat sealing by the horizontal sealing mechanism.
Defective seal resulting from such a difference in height is hereinafter described with reference to
FIGS. 5
a
and
5
b
.
FIG. 5
a
schematically shows a cross section of horizontal seal portion
502
at the time of formatio
Desai Hemant M
Orihiro Engineering Co., Ltd.
Rada Rinaldi I.
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