U.S. patent number 3,889,871 [Application Number 05/335,796] was granted by the patent office on 1975-06-17 for recloseable flexible bag.
This patent grant is currently assigned to E. S. & A. Robinson (Canada) Ltd.. Invention is credited to David B. White.
United States Patent |
3,889,871 |
White |
June 17, 1975 |
Recloseable flexible bag
Abstract
The invention provides a recloseable bag formed of flexible
sheet material comprising a front wall and a rear wall sealed
together adjacent at least one of a pair of opposite edges thereof,
said bag including in a wall thereof an elongated deformable
member, such as a metal wire, extending transversely of said edges
to provide for repeated closure of the bag, the ends of the
elongated member being spaced from said edges of the bag and the
sheet material between the ends of the member and the said edges of
the bag being removed. The invention also provides a method of
producing said bags.
Inventors: |
White; David B. (Willowdale,
CA) |
Assignee: |
E. S. & A. Robinson (Canada)
Ltd. (Toronto, CA)
|
Family
ID: |
27162264 |
Appl.
No.: |
05/335,796 |
Filed: |
February 26, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
288434 |
Sep 12, 1972 |
3859895 |
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Foreign Application Priority Data
Current U.S.
Class: |
383/203;
229/87.09; 383/905; 426/106; 493/215; 383/37; 383/93; 426/412 |
Current CPC
Class: |
B65D
33/30 (20130101); Y10S 383/905 (20130101); B31B
70/8123 (20170801) |
Current International
Class: |
B31B
19/90 (20060101); B31B 19/00 (20060101); B65D
33/30 (20060101); B65D 33/16 (20060101); B65d
033/30 () |
Field of
Search: |
;229/65,63,62,87B,87R
;150/3,11 ;426/412,106 ;93/1TS,35DS,8WA |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Price; William I.
Assistant Examiner: Garbe; Stephen P.
Attorney, Agent or Firm: Stevens, Davis, Miller &
Mosher
Parent Case Text
This application is a continuation-in-part, in the nature of a
divisional, of application Ser. No. 288,434, filed Sept. 12, 1972
now U.S. Pat. No. 3,859,895.
Claims
I claim:
1. In a recloseable bag formed of flexible sheet material
comprising at least a front wall and a rear wall at least one edge
of each of said front and rear walls being sealed together, and
said bag including in the surface of at least one wall thereof at
least one elongate deformable member extending in a direction
transverse to the common direction of said edges which are sealed
together, wherein the improvement comprises that an end of said
elongate member stops short of a line formed by extending the
common direction of said edges which are sealed together, and none
of said flexible sheet material lies in an area between said end of
said deformable member and said line, said area being located
between the ends of said edges which are sealed together, and said
deformable member does not extend into said area.
2. A bag as claimed in claim 1 in which the front and rear walls
are sealed together at two opposite side edges thereof.
3. A bag as claimed in claim 2 in which said elongate member
extends in a direction transversely of the side edges adjacent a
top end of the bag.
4. A bag as claimed in claim 3 in which the front wall and the rear
wall are sealed together adjacent the top thereof, said elongate
member providing for subsequent repeated closure of the bag after
rupture of a seal adjacent the top thereof, and the absence of
flexible sheet between said end and said line material providing
for communication between the interior of the bag and the outside
atmosphere.
5. A bag as claimed in claim 4 which has a sealable open
bottom.
6. A bag as claimed in claim 4 which has a sealed bottom.
7. A bag as claimed in claim 4 including a reinforced header
attached to the top thereof.
8. A bag as claimed in claim 1 in which the front and rear walls
are sealed together at least at the bottom edge thereof, said
elongate member extending transversely of top and bottom edges of
the bag.
9. A bag as claimed in claim 1 in which the elongate member is
attached by means of an adhesive tape.
10. A bag as claimed in claim 1 formed of a thermoplastic sheet
material the seals being heat seals.
11. A bag as claimed in claim 1 which is formed of a thermoplastic
sheet material the seals being heat seals, the elongate member
being attached by a heat sealed thermoplastic tape.
12. A bag as claimed in claim 1 which is formed of a thermoplastic
sheet material the seals being heat seals, the elongate member
being attached in a heat sealed gusset in said wall.
13. A bag as claimed in claim 1 in which the elongate deformable
member is a metal wire.
14. In a recloseable bag formed of a flexible sheet material
comprising a front wall and a rear wall sealed together at or
adjacent two opposite side edges thereof and unsealed at the top
and bottom edges thereof said bag including in a wall thereof an
elongate deformable member extending transversely of each of said
side edges and extending adjacent each unsealed edge to provide for
closure of said bag, the improvement in which the ends of each
elongate member are spaced from said sealed side edges of the bag,
without sheet material between the ends of the member and a line
formed by extending the direction of the side edges of the bag.
15. A bag as claimed in claim 14 in which the elongate member is a
metal foil.
Description
The present invention relates to bags formed from flexible sheet
material, particularly thermoplastic sheet material, such as
polyolefins, preferably polyethylene and a method of producing such
bags. In particular the present invention relates to recloseable
flexible sheet bags which can be repeatedly closed subsequent to
the breakage of the top seal thereof.
Flexible sheet bags such as thermoplastic sheet bags have
heretofore been produced inter alia by continuously passing a pair
of superimposed layers of the sheet material, which layers are
suitably formed by longitudinally folding a single sheet of the
thermoplastic material, along a defined path to a cutting and
sealing station where the layers are cut and sealed, suitably by a
vertically moving hot knife, transversely to the direction of
motion of the layers in the defined path, which hot knife cuts and
seals the sides of the bag to form side seams. During the passage
along the defined path of the layers to the cutting and sealing
station they may be longitudinally sealed adjacent to one end
thereof to provide a header for the bag, the bottom of the bag
being left unsealed for the insertion of the contents into the bag.
When the bag has been filled the bottom of the bag is subsequently
sealed. However, such bags have the disadvantage that once the top
seal is broken to gain access to the contents of the bag the bag is
not recloseable.
A recloseable bag has been shown in U.S. Pat. No. 2,973,131 to Mead
et al. which includes the presence of an opening and closing means
including a tab which extends across the bag adjacent the top end
thereof, the tab extending beyond the side seams of the bag and
including wire therein as a deformable member. While this tab is
effective in providing for repeated reclosing of the bag, the
closure means has to be attached to each individual bag after it
has been fabricated, i.e., after the cutting and sealing station
which necessitates increased handling of the bag and thus
substantially increases the cost of the production of the bag.
British Pat. No. 1,263,761 published Feb. 16, 1972 to TCF Canada
Ltd. discloses a recloseable bag in which the bendable metal wire
extends longitudinally of the bag to provide for reclosing of the
bag.
The present invention provides a bag which includes a closure means
for rendering the same repeatedly openable and closeable after the
rupture of a seal in which less material is necessary to provide
the closure means and in which the closure means can be
incorporated into the bag during the course of its conventional
manufacture without increased handling thereof.
It has now been found according to the present invention that by
applying and sealing a continuous elongated deformable member,
particularly metal wire, to the outer face of one of the layers,
particularly in the aforesaid process, the member being disposed
substantially parallel and adjacent to but spaced from an edge
during its passage along the defined path and by punching holes
through said layers where the member intersects the portion of the
layers which are subsequently cut at the cutting station whereby
the knife does not have to cut through the member thus avoiding
damage thereto, a flexible bag is produced including a closure
means rendering the same recloseable. In addition thereto it is
found that by providing such holes in the bag communication may be
provided between the interior of the bag and the external
atmosphere whereby it is possible to avoid entrapment of air in the
bag when the bottom of the bag is subsequently sealed.
According to the present invention there is provided in a
recloseable bag formed from a flexible sheet comprising a front
wall and rear wall sealed together at or adjacent at least one of a
pair of opposite edges thereof, said bag including in a wall
thereof an elongated deformable member extending transversely of
said edges to provide for repeated closure of the bag, the
improvement in which the ends of the elongated member are spaced
from said edges of the bag, the sheet material between the ends of
the member and said edges of the bag being removed.
In accordance with one embodiment of the present invention the pair
of opposite edges are the side edges thereof both of which are
sealed, the elongated deformable member extending transversely of
said side edges adjacent to either the top or bottom of the
bag.
In a particularly preferred embodiment oof the present invention
the front wall and the rear wall are sealed together adjacent the
top thereof, said wire providing for subsequent repeated closure of
the bag after rupture of the seal adjacent the top thereof and said
removed sheet material providing for communication between the
interior of the bag and the outside atmosphere. The bag of the
embodiment may be in its fillable form and has a sealable open
bottom and is suitably provided with a flap to enhance the sealing
of the bottom thereof or alternatively the bag may be filled with
the goods to be packaged, such as cookies, and has a sealed bottom.
The bag may also be provided with a reinforced header attached to
the top thereof as is conventional.
In an alternative embodiment of the present invention the bag has a
closed bottom, said wire being disposed in a flap portion of the
rear wall extending beyond the front wall.
Again, the bag of this alternative embodiment may be in fillable
form and has a sealable top or alternatively the bag may be filled
with the goods to be packaged and has a sealed top.
In a still further embodiment of the present invention the pair of
opposite edges are bottom and top edges of the bag at least the
bottom edge of the bag being sealed, the deformable member
extending transversely of said edges and longitudinally of the bag
suitably in the center thereof in a similar manner to the aforesaid
British patent.
The present invention also provides a method of making a
recloseable bag of a flexible sheet material which comprises
continuously passing two superimposed layers of said sheet material
along a defined path to a sealing station and a cutting station
where said layers are sealed and cut transversely of their
direction of travel to form a pair of opposite edges of said bag
and during passage along said defined path continuously passing an
elongated deformable member to and sealing said wire on the face of
one of said layers substantially transverse to said edges and
continually punching holes through said layers at the points where
the member intersects the portions of the layers which are
subsequently cut at the cutting station.
In forming the bag with the deformable member transverse to the
side edges thereof the superimposed layers may be cut and sealed
simultaneously by a hot knife to form a weld or can be cut
subsequent to sealing using a cold knife in which case the seal
generally lies slightly inwardly from the side edge of the bag.
In providing the bag according to the preferred embodiment of the
present invention the layers during passage along the defined path
are continuously longitudinally sealed adjacent one edge thereof to
form the top of the bag, the elongated member being sealed on the
outer face of one of said layers essentially parallel to and spaced
from said longitudinal seal.
In providing the bag according to the alternative embodiment of the
present invention the superimposed layers are continuously formed
by longitudinally folding a single sheet of said material to
provide a flap portion in one of such layers extending beyond the
other layer, said elongated member being sealed in the adjacent
flap portion.
In forming the bag with the deformable member transverse to the
bottom and top edges of the bag the seals on the side edges of the
bag are formed without cutting or the superimposed layers are in
the form of a continuous tube. The bottom edge only of the bag may
be cut and sealed using the hot knife as the top edge must be
provided open for the insertion of the contents of the bag and is
then sealed. This may be achieved by having the sealing station
separate from and upstream of the cutting station, a cold knife
being used at the cutting station. Alternatively this may be
achieved by the use of a hot knife providing a weld at the bottom
of the bag which operates on a timed sequence alternately with a
flying knife so as to weld and cut the superimposed layers
alternately.
The flexible material is preferably a thermoplastic material whence
the side, top and bottom seals of the bag are suitably heat seals,
the seals suitably being produced by a hot knife. Particular
thermoplastic materials which may be mentioned include polyolefins,
particularly polyalkylenes, preferably lower polyalkylenes and more
preferably polyethylene. The elongated deformable member is
preferably a metal wire.
In accordance with one embodiment of the present invention the wire
is sealed to the surface of said layer by means of an adhesive tape
which is continuously passed to the face so as to be superimposed
on the wire and the tape is subsequently pressed into contact with
the face to seal the wire to the face.
In another embodiment of the present invention, where the sheet
material is a thermoplastic material, a thermoplastic strip is
continuously passed to the face so as to be superimposed on the
wire and the strip is heat sealed to the face to seal the wire to
the face.
In yet a further embodiment of the present invention where the
sheet material is a thermoplastic material, a gusset is
continuously formed in the layer containing the surface, the wire
being continuously introduced into the gusset and heat sealed
therein.
The present invention will be further illustrated by way of the
accompanying drawings in which:
FIG. one is a perspective view of a bag according to on embodiment
of the present invention;
FIG. 2 is a vertical section through a bag according to an
alternative embodiment of the present invention;
FIG. 3 is a perspective view of a bag according to yet another
embodiment of the present invention;
FIG. 4 is a perspective view partially broken away in vertical
section of a bag according to a still further embodiment of the
present invention;
FIG. 5 is a schematic perspective view of an apparatus useful in
making the bag according to the embodiments of the invention set
forth in FIGS. 1 and 2;
FIG. 6 which is on the same sheet of drawings as FIG. 1, is a
detail of the apparatus according to FIG. 5 showing a method of
attaching the wire to the bag according to one embodiment of the
present invention using an adhesive tape;
FIG. 7 which is on the same sheet of drawings as FIG. 1, is a
detail of the apparatus according to FIG. 5 showing a method of
attaching the wire to the bag according to another embodiment of
the present invention using a thermoplastic tape;
FIG. 8 is a detail of an apparatus according to FIG. 5 showing a
method of attaching the wire to the bag according to yet a further
embodiment of the present invention by means of a gusset;
FIG. 9 is a schematic perspective view of an apparatus useful in
making the bag according to the embodiment of the invention set
forth in FIG. 3;
FIG. 10 is a schematic perspective view of an apparatus useful in
making the bag according to the embodiment of the invention set
forth in FIG. 4;
FIG. 11 is a perspective view of a bag according to another
embodiment of the present invention;
FIG. 12 is a perspective of a bag similar to that in FIG. 11 but
with a different bottom edge seal;
FIG. 13 is a schematic perspective view of an apparatus for making
the bag of FIG. 11; and
FIG. 14 is a schematic perspective view of an apparatus useful for
making the bag of FIG. 12.
Referring to FIGS. 1 and 2 the bag which is suitably formed of
polyethylene has a front wall 1 and a rear wall 2 and has heat
seals 4 along the side edges thereof and a heat seal 5 adjacent the
top thereof. The bottom of the bag has a flap 6 and is open. The
bag may be filled through the open bottom with the desired contents
and the flap then turned up and heat sealed as at 7. In the
unfilled state with the open bottom, the flap 6 has holes 8 therein
by which the unfilled bag may be suspended. At the top of the bag
there is suitably provided a false header 9 which includes a hole
10 by which the filled bag may be suspended after the flap 6 has
been sealed.
Referring particularly to FIG. 1 the bag includes a metal wire 11
held in place on the front wall 1 by a tape 12 which may be an
adhesive tape or a thermoplastic tape which thermoplastic tape is
heat sealed to the front wall 1 of the bag. At the side edges of
the bag semi-circular holes 13 have been punched out which has also
removed the ends of the wire 11 and also provides communication of
the interior of the bag with the external atmosphere and thus
prevents entrapment of air when the bag is closed by sealing the
flap 6.
Referring specifically to FIG. 2 in an alternative embodiment the
wire 11 is held in place in a heat sealed gusset 14 in the front
wall 1 of the bag.
The bags of FIG. 1 may be made with the apparatus of FIG. 5 in
combination with that of FIG. 6 or 7 and that of FIG. 2 with the
apparatus of FIG. 5 in combination with that of FIG. 8.
Referring to FIG. 5 sheet polyethylene 20 is withdrawn from a roll
21. The sheet 20 contains printed portions 22 which form the false
header 9 in the finished bag. The sheet 20 is folded at folder 23
into superimposed layers 24 and 25, the lower layer 25 extending
beyond the upper layer 24 to form the closeable flap 6 in the
finished bag. The folded sheet 20 passes from the folder 23 over
tensioning rolls 26 and is contacted by a header edge sealer 27 to
provide the seal 5 in the bag. The flap 6 in the lower layer 25 has
holes 8 punched therein by punch 28 and the false header 9 has
holes 10 punched therein by punch 29. The folded sheet 20 finally
passes through nip rolls 30 and vertically reciprocating hot knife
31 to provide the edge seals 4 in the bag. Instead of the hot knife
31 the heat seal may be made separately at or adjacent the edge 4
and then separately cut with a knife. The procedure as set forth
heretofore constitutes the standard method of making the bag. In
accordance with the present invention the metal wire 11 is fed to
the upper layer 24 of the sheet 20 from a reel 32 and is sealed
thereto by the techniques shown in FIGS. 6, 7 or 8.
Referring specifically to FIG. 6, adhesive tape 12 is fed from reel
33 to overlay the wire 11 on the layer 24 and tape 12 is pressed
into sealing contact with the layer 24 by pressure roller 34.
Referring to FIG. 7 thermoplastic tape 12 is passed from reel 35 to
overlay the wire 11 on the layer 24 and is maintained in contact by
pressure roller 36 and heat sealed to the layer 24 by hot pressure
roller 37.
Referring to FIG. 8 a gusset 14 is formed in the upper layer of the
sheet 24 by a pair of rigid arms 38 and 39. Arm 39 extends between
the layers 24 and 25 and arm 38 extends into the gusset 14. the
metal wire 11 from reel 32 is fed into the gusset 14 and the gusset
14 is then heat sealed by hot pressure roller 40.
Referring once more to FIG. 5 punch 41 punches out hole 42 in the
sheets 24 and 25 at the points where the wire intersects the
portion of the layers 24 and 25 to be cut by the hot knife 31, thus
avoiding damage to the knife during the cutting operation.
The bag of FIG. 3 comprises a front wall 1 and a rear wall 2 and
has heat seals 4 along the side edges thereof. The top of the bag
is open and the bag may be filled through such top opening with the
desired contents and the opening subsequently heat sealed. The rear
wall 2 includes a flap 50 having a metal wire 11 held in place on
the inside surface thereof by a tape 12 which may be an adhesive
tape or a thermoplastic tape, the latter being heat sealed to the
flap 50, and semi-circular holes 13 are punched at the side edges
of the bag, which holes have removed the ends of the wire 11. The
flap 50 serves to reclose the bag when the sealed opening is broken
to remove a portion of the contents.
Referring to FIG. 4, the flap 50 is double folded at 51 and 52. The
top of the bag is open and is filled with the desired contents
through the opening which is then heat sealed. Metal wire 11 is
attached to the flap 50 and is held in position on the inside
surface of the flap 50 by a tape 12 as shown in FIG. 3 and
semi-circular holes 13 are provided as in FIG. 3. The flap is thus
of a double thickness.
The bag of FIG. 3 may be made with the apparatus of FIG. 9 in which
polyethylene sheet 20 is withdrawn from a roll 21 over tensioning
rolls 3 and is folded at folder 23 into superimposed layers 24 and
25, the lower layer 25 extending at 53 beyond the upper layer 24 to
form the flap 50 in the finished bag. The folded sheet 20 passes
from the folder 23 over tensioning roll 26 and then through nip
rolls 30 and vertically reciprocating hot knife 31 to provide the
edge seals 4 in the finished bag. Metal wire 11 is fed to extension
53 of the lower layer 25 from a wire reel 32 and sealed thereto by
the techniques shown in FIGS. 6, 7 or 8 described previously. A
punch 41 punches out holes 42 in the extension 53 at the points
where the wire 11 intersects the portion of the extension 53 to be
cut by the wire knife 31 thus avoiding damage to the knife during
the cutting operation.
The bag of FIG. 4 may be made with the apparatus of FIG. 10 in
which polyethylene sheet 20 is withdrawn from a roll 21 under
tensioning rolls 3 and during passage between a lower and upper
tensioning roll 3 is contacted by rigid folding arm 54 which
institutes the fold 51 into one edge of the sheet 20 and then rigid
folding arms 55 which introduce the fold 52 into the folder portion
51 formed by the arms 54. The sheet 20 so folded is further folded
at folder 23 to form an upper layer 24 and a lower layer 25, which
upper layer 24 extends beyond the lower layer 25 at 53 to form the
double width flap 50 in the finished bag of FIG. 4. The folded
sheet 20 passes from the folder 23 under tensioning roll 26 and
then through nip rolls 30 and vertically reciprocating hot knife 31
to provide edge seals 4 in the finished bag. Metal wire 11 is fed
to the extension 53 of the upper layer 25 from a reel 32 and is
sealed thereto by the techniques shown in FIGS. 6 or 7 as described
previously. Punch 41 punches out holes 42 in the extension 53 at
the points where the wire 11 intersects the portion of the
extension 53 to be cut by the knife 31, thus avoiding damage to the
knife during the cutting operation.
Referring to FIG. 11, the polyethylene bag comprises a front wall
60 and a rear wall 61 sealed adjacent the bottom edge 63 thereof by
a heat seal 64. The upper end of the bag is open at 65 for the
insertion of the contents thereof and ise then sealed. A metal wire
66 extends longitudinally of the bag and is held in position on the
front wall 60 by an adhesive or thermoplastic tape 67, the
thermoplastic tape being heat sealed to the front wall 60 of the
bag. At the bottom edge 63 of the bag and the top edge 68 of the
bag, semi-circular holes 69 are punched out which also removes the
ends of the wire 66 and provides communication with the external
atmosphere thus avoiding entrapment of air when the bag is closed
by sealing the top edge 68.
Referring to FIG. 12 the bag is identical to the bag of FIG. 11
except the seal at the bottom edge 63 is a weld seal.
The bags of FIG. 11 and FIG. 12 are produced by the apparatus set
forth in FIGS. 13 and 14 wherein a continuous flattened tube of
polyethylene 82 is withdrawn from a supply roll 71 and has applied
to one surface thereof a metal wire 66 from a supply 72, the wire
66 being attached to the surface of the bag by means of an adhesive
tape by the technique shown in FIG. 6 or a thermoplastic tape by
the technique shown in FIG. 7. A punch 73 punches holes 74 in the
tube 82 at points where the wire 66 intersects the portion of the
tube 82 to be cut by the cold knife 75 or hot knife 77 thus
avoiding damage to the knife during the cutting operation.
In FIG. 13 the bottom of the bag is sealed by hot bars 76 before
cutting by downstream cold knife 75 to produce seals 64 in the bag
of FIG. 11. In FIG. 14 tube 82 is alternatively cut by hot knife 77
to form the bottom edge 63 of a pair of bags each with weld seal 70
and then by upstream flying knife blade 78 on chain 79 driven by
sprockets 80 in timed sequence to form unsealed open tops 65 of the
pair of bags which are subsequently sealed after insertion of the
contents of the bag.
Heretofore, there has generally been disclosed a recloseable bag
formed for a flexible sheet material comprising a front wall and a
rear wall sealed together at or adjacent to at least one pair of
opposite edges thereof, the bag including in a wall thereof an
elongated deformable member extending transversely of the edges to
provide for repeated closure of the bag in which the ends of the
elongated member are spaced from the edges of the bag, the sheet
material between the ends of the member and the edges of the bag
being removed.
In the embodiments specifically shown in the drawings, the bag
before filling has one end thereof sealed and the other end thereof
open for filling of the bag with its contents which end may
subsequently be sealed or closed by the elongated deformable member
which is located in a wall of the bag adjacent the open end.
The present invention also specifically includes bags open at both
ends thereof for insertion of the contents such as are used in
cooking meat and poultry in ovens, which bags are sometimes
referred to as oven sheaths, the open ends of the bag being
closeable by elongated deformable members in a wall of the bag
adjacent each open end of the bag.
According to a particular embodiment of the invention therefore
there is provided in a closeable bag formed of flexible sheet
material comprising a front wall and a rear wall sealed together at
or adjacent to both of the side edges thereof and are unsealed at
the top and bottom edges thereof, said bag including in a wall
thereof, an elongated deformable member extending transversely of
said side edges adjacent each unsealed edge to provide for closure
of said bag, the improvement in which the ends of each elongated
member are spaced from the edges of the bag, the sheet material
between the ends of each member and the edges of the bag being
removed.
The present invention also provides a method of making such a bag
of flexible sheet material which comprises continuously passing a
pair of superimposed layers of said sheet material along a defined
path to a sealing station and a cutting station where said layers
are sealed and cut transversely of their direction of travel to
form a pair of opposite side edges of said bag with the bottom and
top edges thereof open and during passage along said defined path
continuously passing an elongated deformable member to and sealing
said member on the face of one of said layers transversely of said
side edges adjacent each open edge and continually punching holes
through said layers at points where the member intersects the
portion of the layers which are subsequently cut at the cutting
station.
The superimposed layers may be formed of two separate sheets.
Alternatively, the superimposed layers may be formed from a single
sheet folded in half during its passage along the defined path and
the sheet is slit along the fold. Further, the superimposed layers
may be formed from a single sheet by folding over its longitudinal
edges to lie in abutment with each other during passage along the
defined path, the sheet being slit longitudinally along each fold
and also along the center between the adjacent abutting edges.
The further particular embodiment of the present invention will be
further illustrated by way of FIGS. 15 to 19 of the accompanying
drawings in which;
FIG. 15 is a front elevation of an oven sheath according to one
embodiment of the present invention;
FIG. 16 is a front elevation of an oven sheath according to the
alternative embodiment of the present invention;
FIG. 17 is a schematic perspective view of an apparatus useful for
making the oven sheath of FIG. 15 and 16 according to one
embodiment of the present invention;
FIG. 18 is a schematic perspective view of an apparatus useful for
making the oven sheath of FIGS. 15 and 16 according to another
embodiment of the present invention and
FIG. 19 is a schematic perspective view of an apparatus useful for
making the oven sheath of FIGS. 15 and 16 according to yet another
embodiment of the present invention.
Referring to FIGS. 15 and 16, the oven sheath which is suitably
made of polyethylene comprises a front wall 101 and a rear wall
102. Referring to FIG. 15, the oven sheath has heat seal 103 along
the side edges thereof and referring to FIG. 16, the oven sheath
has weld seals 104 along the side edges thereof. The top and bottom
edges of the oven sheath are open. The oven sheath includes an
elongated metal member such as a metal wire 111 or metal foil,
which is held in place on the front wall 101 in a similar manner as
in FIG. 1. At the side edges of the sheath, semicircular holes 113
have been punched out with the removal of the metal member 111.
Referring to FIG. 17, the oven sheath of FIG. 16 is produced by
withdrawing a pair of sheets 120 from supply rolls 121 and passing
the superimposed sheets along a path over tensioning rolls 126 to a
pair of nip rolls 130. Metal wire 111 is fed from rolls 133 onto
the upper sheet 120. After the superimposed sheets 120 have left
the last tensioning roll 26, wires 111 are attached to the upper
sheet 120 at six points by the techniques described with respect to
FIGS. 6 and 7. The superimposed sheets 120 are further cut
longitudinally of their path by knives 134 to provide for the
simultaneous production of three oven sheaths. Holes 142 are
punched out of the sheets 120 by punches 141 at the points where
each wire 111 intersects the portion of the sheets 120 which are to
be cut by the hot knife 131 thus avoiding damage to the knife 131
during the cutting operation. The sheets 120 are subsequently cut
transversely of their path on passage through the nip rolls 130 by
the hot knife 131 to produce a weld seal on each side edge of the
oven sheath.
Referring to FIG. 18, the sheath of FIG. 16 is produced by folding
the longitudinal edges of a sheet 120 of polyethylene withdrawn
from a supply roll 121 upwardly and inwardly until their
longitudinal edges contact at 135. The superimposed layers of the
sheet 120 are then passed along a path over the tensioning rolls
127 to nip rolls 130. Subsequent to the passage of the superimposed
layers of the sheet 120 over the last tensioning roll 126, the
superimposed layers are longitudinally cut by a knife 134 at the
abutment of the longitudinal edges and also along the longitudinal
folds as to simultaneously produce a pair of oven sheaths. As in
the process of FIG. 17, metal wire 111 is fed from supply reels 133
to the upper layer of the superimposed layers according to the
techniques of FIGS. 6 and 7 and holes 142 are punched in the
superimposed layers by punches 141 at points where each wire 111
intersects the portion of the superimposed layers which are to be
cut by the hot knife 131 thus avoiding damage to the knife 131
during the cutting operation.
The superimposed layers of the sheet 120 are then cut transversely
of their path on passage through the nip rolls 130 by the hot knife
131 to produce a weld seal on each side edge of the sheets.
Referring to FIG. 19, the oven sheath of FIG. 16 is formed by
folding in half a sheet 120 withdrawn from supply roll 121 by means
of the folder 123 to provide equal superimposed layers. These
layers then pass along a path through tensioning rolls 126 to a
pair of nip rolls 130. During passage along the path and after
leaving the last tensioning roll 126, the folded edge of the sheet
120 is slit by a knife 134. As in FIG. 17, metal wire 111 is fed
from supply reels 133 to the superimposed layers according to the
techniques of FIGS. 6 and 7 and holes 142 are punched in the
superimposed layers by punches 141 at points where each wire 111
intersects the portion of the superimposed layers which are cut by
the hot knife 131 thus avoiding damage to the knife 131 during the
cutting operation. The superimposed layers are then cut
transversely of their path on passage through the nip rolls 130 by
the hot knife 131 to produce a weld seal on each side edge of the
oven sheath.
To form the oven sheath of FIG. 15, there is used instead of a hot
knife 131 in the apparatus of FIGS. 17 to 19 to produce a weld
seal, a pair of hot bars and a cold knife to effect cutting and
sealing of the side edges in a similar manner as in FIG. 13.
* * * * *