US2821337A - Gusset bottom bag - Google Patents

Description

Jan. 28, 1951s.'

Original Filed June 3, 1952 T. B. MORGAN, JR

GUSSET BOTTOM BAG 3 Sheets-Sheet 1 Cad/14n Jan. 28, 1958 T. B. MORGAN, JR 2,821,337

GUssET BOTTOM BAG original .Filed Juneis, v1952 s sheets-sheet a Jan. 28, 1958 T. B. MORGAN, .JR

GUssET BOTTOM BAG 3 Sheets-Sheet Original Fil'ed June 3v, 1952 ravin United States yPatjetit GUssET BOTTOM BAG Trac B. Mor an Jr. Rockford Ill. assignor, by mesne asgignmentsgto Hariild L. Bartelt arid Donald E..Bartelt, both of Rockford, Ill.

Continuation of application Serial' No. 291,406, .lune 3, 1952. This application December 6, 1954, Serial No. 473,191

1 Claim. (Cl. 229-57) This invention relates to a bag comprising two panels sealed together along opposite side margins and formed across the bottom of the bag with a gusset of generally W cross section adapted to be expanded by the material delivered into the open top of the bag. i

The primary object of the invention is to prov1de a novel construction of the bag corners at the junction of the side seals and the gusset or bellows bottom which construction, upon receiving the material to be packaged, is expanded in a novel manner to a squared cross section.

Another object is to provide at the bag corners ilaps of novel construction which, as an incident to filling the bag, turn outwardly and upwardly automaticaly and form guides which facilitate insertion of the bag in a carton of minimum size and at the same time control the bending over of the side seams to prevent the latter from interfering with such insertion.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which:

Figure 1 is a front elevation of the bag constructed in accordance with the present invention.

Fig. 2 is a perspective view showing the bag partially o en.

pFig. 3 is a fragmentary perspective view of the bottom of the bag.

Fig. 4 is a perspective View of the bag fully opened.

Fig. 5 isa sectional view taken along the line 5--5 of Fig. 2.

Fig. 6 is a fragmentary side view.

Fig. 7 is a schematic perspective view illustrating the manner in which the bags are made. p

Fig. 8 is a schematic perspective view showing the manner in which the bags are folded.

Fig. 9 is a perspective view of the completed bag.

Fig. 10 is a fragmentary perspective view of a corner of the bag.

Fig. 1l is a perspective view of one of the sealing elements.

Fig. l2 is a fragmentary view showing the relative sizes of a box and a flattened bag.

Figs. 13, 14 and l5 are fragmentary views illustrating successive steps in inserting the bag when filled in a carton or box.

The bag 15 shown in the drawings for the purposes of illustration comprises front and back panels 16 joined together along their side edges to form a narrow band-like seam indicated at 17. Along the bottom, the bag material is folded or tucked in across its full width to form two outer folds 18 (Fig. 5) and a reverse fold 19 between the outer folds. Thus the folded portion of the bag is of W cross section forming a bellows-like fold as shown in Fig. 5 and the adjacent pairs of legs of the W constitute double-walled flaps 20. At each end of each llap, the inner and outer walls 21 and 22 of each ilap are joined together over a generally triangular area including the llap corner and terminating at an inner edge 29al which starts at the point 29 of intersection of the inner end of the fold 19 and the inner edge of the side seam 17 and extends diagonally inwardly at an angle of about 45 degrees to the flap edge 18.

When the bag is opened, the bellows or W-shaped gusset is flattened out by unfolding of the flaps 20 so that the inner walls 21 of the two flaps lie substantially in the same plane to form a generally llat and rectangular bottom wall 24 as shown in Fig. 3, the outer walls 22 becoming part of the sides of the bag. Due to the trinagular shape of the seals 23, the joined end portions of the tlaps 20 turn up about a fold line 25 as the bag is being opened, and the unsealed triangular portions 26 of the llaps 'be-l tween the seals 23 are bent upwardly and eventually become part of side walls 27 (Fig. 4).

I have discovered that, by using a particular type of seal to make the side seams 17, the latter may be made before the bag is opened and may be extended throughout the entire length of the bag without interfering with the unfolding and the action of the flaps 20 in bending upwardly automatically as an incident to expanding the bellows fold. This seam is formed by joining together the opposed side margins of the front and back panels 16 in face to face relation, that is, the inner surface of the narrow elongated portion along the edge of the front panel is sealed to the corresponding inner surface of the back panel. As shown in Fig. 1, the side seams 17 extend all along the edges from the top to the bottom of the bag but do not join together the adjacent end portions of the two folds 20 which are thus left free from each other all along their lengths from one edge of the bag to the other.

While the side seal 17 leaves a narrow band 30 projecting outwardly from the side edges of the bag 15, this band does not prevent the end portions of the flaps 20 from turning upwardly as an incident to expansion of the bag. Since the band 30 is narrow and flexible, it buckles at a point 31 just above the diagonal seals 23 when the flattening of the infold is begun as shown in Fig. 3. As the upward bending of the llaps is continued, this buckling causes the bands 30 to turn over and lie substantially tlat against the side walls 27 of the lled bag as illustratedA in Fig. 10. At the same time, the portion 32 of the band 30 below the point 31 turns back upon itself along a line 33 and forms a triangular fold permitting the diagonal seal 23 to be drawn up close to the side wall so that the triangle portion 26 of the flaps 20 may eventually lie substantially in the plane of the side wall 27 as shown in Fig. 4. p

The buckling and folding of the bands 30 and the partial turning -up'of the sealed parts 23 of the ilaps 20 occur automatically in the opening of the bag. O ne way of opening the bag preparatory to filling is by directing a jet of air into the interior of the bag. TheI air spreads the front and back panels 16 apart and forces.

' l the llap walls 21 down to expand the infold 19 and form the llat bottom 24. Due to the diagonal corner seals 23, the portions of the llaps 20 forming the triangular piece 26 cannot unfold completely until the end portions of the flaps have been turned up through a right angle. `Since the air unfolds the ends of the flaps as well as the central portion, the end portions of the -llaps are forced to fold upwardly as shown in Fig. 3.

Since the band 30 does not interfere with the opening of the bag, the triangular sea'led area-s 23 and the side seals 17 may be formed while the bag is in the ilattened condition shown in Fig. 1. For this reason, the bag is capable of being made on a high-speed automatic machine.' The latter, for example, may be of the type in which the bags are made by unwinding a strip '34 (Fig. 7) of bag material from a supplyroll 35 and advancing the strip endwise along a rectilinear path. During a portion of the advance indicated at 36, the strip is folded longitudinally as it advances 'through the machine and feed rollers 37 engage the opposite sides of the folded Strip to move it along its path. The folding operation, illustrated in Fig. 8, includes drawing the strip 34 over a former (not shown) to give the strip a narrow U-shaped cross section indicated at 37. In the continued advance f the strip, a blade 38 engages and folds in the bottom of the U giving the lower portion of the strip the W cross section and forming the aps 20.

After the folding operation, the diagonal and side seals 23 and 17 are made at a station 39. Preferably, the seals are formed through the application of heat and pressure and, for this purpose, the inside of the 'strip 34 is coated with a thermoplastic substance which will soften when heated above a predetermined temperature and enable selected areas of one side of the folded strip, when pressure is applied, to fuse with and become integrally joined to the corresponding areas of the other side of the strip. At the station 39, a pair of shoes 40 -heated above the temperature at which the thermoplastic substance Isoftens press against opposite sides of the folded strip 34.

As shown in Fig. ll, the surface 41 of each shoe 40 is rectangular from the upper edge of the folded strip 34 down to the fold 19 and is twice as wide as the seal 17. Below the fold 19, the lsurface flares outwardly and downwardly on ea-ch side at a 45 degree angle. When the strip 34 is pressed between the shoes, the thermoplastic material between the shoes softens and opposed portions of the strip become united. Since only the inner surface of the strip is coated, the separate flaps or V-shaped folds of the bellows bottom are not joined together but remain separated and of W shape in cross section. Thus the shoes form a single seal 17a which constitutes the edge and diagonal seals 17 and 23 on the trailing edge of one bag and also the corresponding seals on the leading edge of the succeeding bag.

At a subsequent station 42, the strip is severed intermediate the edges and along the longitudinal center 'line of the seal 1794 which was made by the shoes 40. The bags thus formed then are advanced lst to a station 43 where they are opened preparatory to lilling and then to a filling station 44. Disposed above the bag at the station 43 is a nozzle 45 which directs a stream of air downwardly toward the mouth of the bag. As described above, -the air spreads the panels 16 apart and expands the bellows bottom 18 to give the bag a generally squared cross section. The bag then is advanced to the lling station 44 where a charge of material to be packaged is delivered to 'the bag from a dispenser 46. If desired, the bag may then be closed by collapsing the open end of the bag and sealing the upper ends of the panels 16 together.

AIt: will be observed that the improved bag as described above may be formed completely before it is opened, that is, both of the band-like side seals 17 and the triangular seals 23 with the diagonal inner edge 29a are formed while the panels 16 are still flat against each other. `It is not necessary, therefore, to open and close the bagl and to fold and unfold the flaps 20 in the process of making the bag. IInstead, all of the seals are made by the single operation of pressing the bag between the shoes 40. This is a simple operation which is capable of being performed automatically making it possible to produce the bags rapidly on a high-speed machine.

[By virtue of the gusset bottom, the extension of the corner seals 2,3 inwardly to the diagonal line 29, and the separation of the folds 20 from each other throughout the ful'l length of the gusset, the improved bag possesses numerous advantages over prior constructions. In 'the first place, the gusset bottom expands automatically -rst as shown in Fig. 2 and then to a generally at rectangular shape (Fig. 3.) `as an incident to regular machine opening and filling operations. Such squaring olf of the bag bottom induces bending of the side panels along longitudinal lines 28 (Figs. l and 3) near the panel margins thereby assisting in shaping the upper portions of the bag and the contents thereof into a generally rectangular cross-section. As a result of the filling and tapping or settling operations normally performed in high speed packaging machinery, the `filled bag may easily be worked substantially into the squared shape shown in Fig. 4.

A second and most important advantage of the gusset bottom construction above described is that it enables a bag lled with a given volume of material to be handled and inserted by machine handling in a rigid Walled carton 50 (Fig. l2) of smaller size than is possible with prior bag constructions. This advantage results from the novel shaping of the bag lcorners and the upward bending of the separated flaps that occurs as a natural incident to the delivery of the material charge into the bag during machine lling thereof.

This action is illustrated in Figs. 12 to l5 from which it will be observed that the edge walls 51 are spaced apart a distance substantially less than the width of the attened or unfilled bag shown above the open end of the carton in Fig. 12. As above described and shown in Fig. 3, the delivery of a charge of material downwardly into the bag results Anot only in a squaring olf of the bag bottom but also in bending of the triangular seals 23 at the ends of the separated folds 20 upwardly through a substantial angle, at the same time initiating upward bending of the bottom parts along the lines 25.

By such shaping and bending as a natural incident to machine lling, the bag bottom may be inserted into the carton by a single endwise movement Without interference or danger of rupture. As the squared bottom 24 enters the open end of the carton as shown in Fig. 13, the upturned flaps 23 at points spaced outwardly from the lines 25 encounter the upper edges 52 of the carton Walls 51. These flaps are cammed inwardly as the lowering of the bag continues (see Fig. 14) with the result that the material in the bag is shifted slightly to cause further squaring of the bag edges as the aps 23 are cammed inwardly.

Next, the carton edges 52 encounter the lower ends of the side seams 17 but, since a lateral bending or buckling thereof as indicated at 31 has already taken place, the edges act as cams to continue the bending as indicated at 32 (Fig. l0) and then turn the entire seam over against the edge 27 of the squared bag as shown in Fig. 15. Such bending of the side seams continues progressively as the bag is advanced into the carton and the entire seam is eventually brought flat against the bag edge 27. In this way, completion of the squaring off of the bag and its contents and shaping thereof to conform to the desired minimum internal dimensions of the carton is achieved automatically during a simple cartoning operation. It will thus be seen that no auxiliary guides for a bag are needed and there is no danger of rupturing the filled bag during cartoning thereof which may be effected at minimum cost with automatic machinery.

It will be seen that, even though the opening and filling operations do not bend the corners up fully to the position shown in Fig. 4 but leave the bag in shape shown in Fig. 3, the bag nevertheless may be inserted into a carton of minimum size. Such inserting completes the folding up of the corners and the buckling and folding over of the side seals 30. Thus, in all cases, the opening and filling operations at least condition the bag so that the final squaring and shaping occurs as an incident to the insertion of the bag into the carton.

This application is a continuation of my prior application Serial No. 291,406. led J une 3, 1952, now abandoned.

I claim as my invention:

A gusset bottom bag comprising front and back panels integrally joined together across the bag bottom and heat sealed together along their side margins to form bandlike seams, said bottom being tucked inwardly to form a W cross section between said seams composed of two outer V-shaped folds forming between them an intermediate reverse fold having side walls which are separated from each other throughout the full width of the bag, and four corner seals joining the opposed walls of said outer folds together at the ends thereof and to an inner edge extending diagonally and inwardly substantially from the intersections of the inner edge of said side seams and the apex of said reverse fold, said corner seals constituting 6 separated aps which, as an incident to expansion of the gusset bottom of the bag, bend upwardly automatically and initiate lateral bending of the lower ends of said side seams.

References Cited in the file of this patent UNITED STATES PATENTS 2,283,069 Knuetter May 12, 1942 2,378,503 Rohdin June 19, 1945 2,401,109 Rohdin May 28, 1946 2,406,791 Belcher Sept. 3, 1946

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