Machine and method for manufacturing plastic pouches

The machine and the method disclosed use a panel plastic film that is longitudinally folded into top and bottom halves before slitting along the fold. The halves are simultaneously transported ensuring print registration and requiring a single accumulator in the longitudinal direction. Side gusset pieces are inserted between the top and bottom halves through an initial gap enlarged by a pair of timing belts. The top and bottom halves partly sealed with the side gusset pieces are pulled away from each other and a means gives the ends of the side gusset pieces the shape of a rhomboid. Bottom gusset film is vertically sealed along the vertical axis of the rhomboid shaped ends of the side gusset pieces with the seal extending to the folded portions of the top and bottom halves. Longitudinal sealing and transverse sealing before cutting ensure sealing of the bottom gusset and side gussets.

FIELD OF THE INVENTION

The present invention relates to a machine and a method for manufacturing plastic bags or pouches with three gussets.

BACKGROUND OF THE INVENTION

High speed machines and methods for manufacturing plastic bags or pouches in large quantities, are known. Also known are high speed machines and methods for manufacturing pouches with side gussets and bottom gusset. Manufacturing methods and machines are also known and available for producing standing plastic pouches. Plastic pouches with or without gussets can be produced having a top that can be closed and opened.

Machines for producing plastic pouches having gussets and methods for producing the same have been patented.

U.S. Pat. No. 7,331,917 discloses a Bag Making Machine which uses separate sources for the top and bottom or front and back plastic web panels requiring multiple accumulators. The separate feeding of the web panel films causes mismatch of designs necessitating a re-unification assembly to address the design matching problem. Apart from this, the machine according to this invention provides little flexibility in terms of the width of the plastic film that the machine can use.

US Patent application no. 2012/0231941 discloses a Plastic bag making apparatus wherein the gusset portions have been separately attached and temporarily fixed to the main two films. The gusset portions need to be separately attached because of which the process is long and to match the registration or print of the plastic bags becomes difficult. Such process has a need for re-unification assembly so as to overcome the barrier of mechanical distance and hence, the machine and method makes it difficult to manufacture gusseted plastic bags compromising production efficiency.

U.S. Pat. No. 6,796,932 discloses a manufacturing method and apparatus for manufacturing gusseted bag using two separate films and a bottom gusset. However, the bottom gusset structure is separately placed between the two layers of the main film and then heat-sealed to form the bottom gusset. In this invention two main plastic films and one bottom gusset plastic film have been used requiring multiple accumulators. The machine does enhance production efficiency, but it increases the cost of manufacturing the plastic bags with gussets as three separate plastic films have been used. The machine also requires large floor space for installation and operation.

The present invention alleviates the abovementioned disadvantages and shortcomings of the machines and processes for manufacturing plastic pouches with three gussets.

SUMMARY OF THE INVENTION

The principal object of the machine and method in accordance with the present invention is to provide a simplified machine for manufacturing plastic pouches or bags having two side gussets and one bottom gusset. Since the source of the panel plastic film unlike in the prior art is common the problem of mismatch in design registration is efficiently solved. This also eliminates the need for having more than one accumulator in longitudinal direction. Also, the need for having a means and a method to unite at some point the differently fed top and bottom halves of the plastic film is eliminated.

Additionally, the method of transforming the ends of the side gusset pieces into rhomboid shaped ends as disclosed in the present invention eliminates the need of complicated machinery and thereby provides an efficient, accurate and simplified method for producing the said rhomboid shaped ends. This also eliminates complicated machinery found in the prior art.

Having fewer components reduces not only the cost of the machine, but also reduces the floor space occupied by the machine. This is another object of the present invention.

The present invention is flexible to make plastic pouches that are tall and wide. The prior art machines cannot handle tall plastic bags clue to inflexibility of the machine to handle wide panel plastic film.

As aforementioned, the machine and the method in accordance with the present invention use a panel plastic film from a single unwinding reel as opposed to the different sources for providing top and bottom panel films as in the prior art.

The panel plastic film is longitudinally folded into top and bottom halves and is transported in longitudinal or machine direction. A slitter slits the panel plastic film along the longitudinal fold to cut the film into to and bottom halves. The top and bottom halves simultaneously get transported ensuring that any design common to the top and bottom halves will always accurately match unlike the prior art machines where the top and bottom halves originate from separate sources and at some stage, using complicated machinery, are united. The machine in accordance with the present invention, because of this unique feature of providing the top and bottom halves from folding the panel plastic film unwound from a single unwinding reel, requires only a single accumulator. This significantly reduces the complexity of the machine and requires fewer parts than the machines disclosed in the prior art.

The slitting of the top and bottom halves by the slitter creates an initial gap between the top and bottom halves of the panel plastic film. The said gap is enlarged by a pair of timing belts positioned transversely such that the bottom portion of the top timing belt is substantially in contact with the top portion of the bottom timing belt. The said timing belts have teeth on the inside. The teeth of the timing belts mesh with the teeth on the sprockets on either side. The top half of the panel plastic film passes through the first timing belt such that the bottom surface of the top half of the panel plastic film is in contact with the top of the teeth on the lower portion of the top timing belt. Similarly, the bottom half of the panel plastic film passes through the bottom timing belt such that the top surface of the bottom half of the panel plastic film is in contact with the top of the teeth on the top portion of the bottom timing belt. Thus, the gap between the top and bottom halves of the panel plastic film will be substantially equal to the total of thicknesses of the top and bottom timing belts including the heights of the teeth on both the timing belts. The enlargement of the gap at this stage is required to allow insertion of the side gusset pieces between the top and bottom halves of the panel plastic film.

The machine in accordance with the present invention can have the feeding line for side gusset pieces that can be transversely positioned on either side of the machine depending on the requirements of the customer and space constraints. Side gusset film is unwound from an unwinding reel and is guided by a guide roller to be directed to an accumulator roller. The side gusset film exits a nip and gets folded by a folding device such that the folded portions are on the top and the total width of the top folded portions is substantially same as the width of the bottom portion of the side gusset film. A creasing device ensures that the front and rear folded edges maintain their crease. The side gusset film gets further transported in the transverse direction through an index nip and gets cut into side gusset pieces by a cutter. The rate of indexing depends on the positioning of the side gusset pieces between the top and bottom halves of the panel plastic film. In other words, the width of the plastic pouch will determine how far apart the side gusset pieces are positioned between the top and bottom halves of the panel plastic film which in turn determines the rate of indexation. Therefore, the wider the plastic pouch, the slower will be the rate of indexation and vice versa. The side gusset pieces get inserted between the top and bottom halves of the panel plastic film through the said enlarged gap.

A transverse heat sealer seals the side gusset pieces with the top and bottom halves of the panel plastic film. The seal is along the length of the side gusset pieces sealing the free edges of the top folded portions with the top half of the panel plastic film and the corresponding middle of the bottom portions of the side gusset piece with the bottom half of the panel plastic film.

The next stage is to give the ends of the side gusset pieces the shape of a rhomboid. The top half and the bottom half of the panel plastic film are pulled away from each other. This action opens the side gusset pieces in such a way that the cross-section of the space inside the side gusset pieces resembles a rhomboid like shape having a rounded corner on the front folded edge as well as on the rear folded edge of the side gusset piece ends. Using a roller, the said front rounded corner is pushed inwards near the vertical axis of the rhomboid shaped space and similarly, using another roller, the rounded rear corner is also pushed inwards to be near the said vertical axis. This action transforms the end of the side gusset pieces into rhomboid shaped ends that will now have a new front corner on the front folded edge and a new rear corner at the rear folded edge. Also, it will have a top corner at the seal and a bottom corner at the seal.

The pulling action of the top and bottom halves of the panel plastic film will result into a folded portion of the top half and similarly, a folded portion of the bottom half of the panel plastic film. The folded portions are relatively small in size compared to the remaining greater portions of the top and bottom halves and are generally perpendicular to the remaining greater portions of the top and bottom halves of the panel plastic film.

The edge of the folded portion of the top half will project beyond the top corner of the rhomboid shaped ends and likewise, the edge of the folded portion of the bottom half will project beyond the bottom corner of the rhomboid shaped ends. In other words, the combined height of the folded portions of the top half and the bottom half of the panel plastic film will be greater than the height of the rhomboid shaped ends.

Bottom gusset film unwinding from and unwinding reel is transported in transverse direction up to a point where a turn bar is provided which changes the direction as well as the orientation of the bottom gusset film which gets reoriented to be now transported in longitudinal direction such that the edges of the bottom gusset film remain horizontal, but in a plane perpendicular to the plane when it was being transported transversely. In this position, the bottom gusset film would be substantially parallel to the rhomboid shaped ends as well as the folded top and bottom portions of the panel plastic film. The bottom gusset film at this stage is substantially in contact with the full faces of the rhomboid shaped ends as also the folded top and bottom portions of the top and bottom halves of the panel plastic film.

The next stage is to vertically heat-seal the bottom gusset with the rhomboid shaped ends along the vertical axis of the rhomboid shaped ends of the side gusset pieces. The bottom gusset also gets sealed with the top and bottom folded portions of the top and bottom halves of the panel plastic film where the top and bottom folded portions respectively project above and below the top and bottom corners of the rhomboid shaped ends.

The top and bottom halves of panel plastic film together with side gusset pieces and the vertically sealed bottom gusset film with the rhomboid shaped ends as well as the folded portions of the top and bottom halves of panel plastic film get further transported in longitudinal direction. The bottom gusset film with the rhomboid shaped ends as well as the folded portions of the top and bottom halves of panel plastic film pass through an index nip.

The next step is to collapse the bottom gusset film with the rhomboid shaped ends as well as the folded portions of the top and bottom halves of panel plastic film such that the rhomboid shaped ends have the top corners substantially contacting the bottom corner resulting in a triangular top part and a triangular bottom part. At this stage, the top and bottom edges of the bottom gusset film also would be substantially in contact with each other as well as the edge of the top half and the edge of the bottom half also would be substantially in contact with each other. It can be seen that at this stage, the folded portions of the top and bottom halves of the panel plastic film get unfolded.

The so collapsed top and bottom halves of panel plastic film together with side gusset pieces and the bottom gusset film with the rhomboid shaped ends as well as the folded portions of the top and bottom halves of panel plastic film get further transported in longitudinal direction and are ready for final longitudinal and transverse sealing before getting cut into pouches.

A longitudinal heat sealer seals the top edge of the bottom gusset film with the edge of the top half of the panel plastic film and simultaneously, in a reciprocating action, the bottom edge of the bottom gusset film gets longitudinally sealed with the edge of the bottom half of the panel plastic film.

A transverse heat sealer seals the top edge of the side gusset pieces with the edge of the top half of the panel plastic film in a reciprocating action, the bottom edge of the side gusset pieces get sealed with the bottom half of panel plastic film.

The transverse sealing also seals the front collapsed edge of the bottom gusset film with the corresponding collapsed edge of the side gusset piece in the front. Similarly, the rear collapsed edge of the bottom gusset film gets sealed with the corresponding collapsed edge of the side gusset piece in the rear.

The next step is to cut along the transverse seal and more than one cut may be required to produce plastic pouches having two side gussets and one bottom gusset.

DETAILED DESCRIPTION OF THE DRAWINGS

The machine in accordance with the present invention is designed and arranged to efficiently make plastic bags or pouches, each of which includes two side gussets and a bottom gusset.

Plastic bags and pouches come in a wide variety. Most plastic bags will have something printed on them. The printing may include words or artwork. Many times, the artwork on the front and the back sides of the plastic bags or pouches will be identical and symmetrical. Such plastic bags or pouches may be transparent, translucent, or opaque. In any case, whether the plastic bags or pouches are transparent, translucent, or opaque, the artwork on both the sides must match. This poses a technical problem which most manufacturers struggle to solve. Complicated and expensive machineries have been invented and developed. Some have even been patented as described hereinabove. Such matching of the artwork or design or print registration in the machine in accordance with the present invention is achieved accurately and in a simplified manner. Also, the insertion and placement of the side gussets between the top and bottom panel plastic films or front and back as the case may be, is achieved in a simplified manner utilizing fewer machine components.

The principles of operation of the machine in accordance with the present invention and the method of using the machine to produce plastic pouches with two side gussets and a bottom gusset will be described hereinbelow with reference to the accompanying drawings.

The machine in accordance with the present invention includes several parts. In the description of the machine in accordance with the present invention, the machine direction is referred to as the longitudinal direction as the transformation of the panel plastic film or the mother film into final products such as plastic bags or pouches occurs in this direction. The panel plastic film or mother film will have to be fed into the machine. In the machine in accordance with the present invention, this is done using an unwinding means and a folding means positioned such that the feeding of the panel plastic film or mother film occurs in a direction transverse to the longitudinal or machine direction. This feeding line is positioned to be on a side that is opposite to the side where such feeding lines for side gussets and bottom gusset film are located in the machine in accordance with the present invention. Location of such feeding lines could be altered to suit the floor space available and according to the choice of the plastic bag or pouch manufacturer.

Thus,FIG. 1shows a side view of the major components in the longitudinal direction50of the machine in accordance with the present invention. Panel plastic film10is shown to be unwinding from the unwinding reel15. A folding device20folds into two equal halves—top and bottom—the panel plastic film10. This is shown to happen in a direction transverse to the machine or the longitudinal direction50; however, this could be done in other manner as a person skilled in the art would readily understand.

The panel plastic film10, if it is having identical or symmetric design or artwork on the top and bottom halves or the front and back sides, the design or artwork will be accurately matched or registered here itself with the folding into two equal halves.

The folded panel plastic film10, now having the top half30and bottom half40, is transported using guide rollers23in longitudinal direction50to a single accumulator70through a capstan nip60. Since the machine in accordance with the present invention uses a single source for the top and bottom halves30and40respectively of the panel plastic film10, it uses only a single accumulator70in the longitudinal direction50. Thus, the machine in accordance with the present invention provides for accurate design registration using fewer components and a simplified method as will be explained hereinbelow.

The folded panel plastic film10into top and bottom halves30and40respectively is further transported in longitudinal direction50through an index nip80. Film slitter90slits along the fold the folded panel plastic film10into top and bottom halves30and40respectively. The slitter also creates an initial gap between the top half30and bottom half40.

FIG. 2shows a diagrammatic perspective representation of the transformation of the panel plastic film10into plastic pouch260with placement of side gussets95at fixed intervals and bottom gusset film430attachment at different stages in accordance with the present invention. Also, shown is the longitudinal seal240sealing the bottom gusset430with the side gussets95and the top and bottom halves of the panel plastic film30and40respectively. Transverse seal250seals side gussets95with the bottom gusset film430and the top half30and bottom half40of the panel plastic film10.

FIGS. 1 and 2show the overall progression of the transformation of the panel plastic film10into plastic pouch260. Detailed operation of the feeding lines for the side gussets95and bottom gusset film430will be explained with reference to other drawings.

FIG. 3shows the side view of the major components of the machine in accordance with the present invention arranged in transverse direction290for the purpose of providing side gusset pieces95. Side gusset film280is unwound from the unwinding reel270in the transverse direction290. Bending around capstan nip285, the side gusset film280is transported around accumulator roller300and is further transported in transverse direction290through capstan nip310. At this stage, the side gusset film280is longitudinally folded using folding means320and a creasing device340shown inFIG. 4such that the front and rear folded portions335and336respectively are on the top and the combined width of the front and rear folded portions335and336respectively is substantially same as the width of the bottom portion.FIG. 4shows a diagrammatic perspective representation of the transformation of the side gusset film280into side gusset pieces95in accordance with the present invention. As shown inFIG. 4, the folded side gusset film330is further transported through capstan nip345around accumulator roller350and through a tail feed360. A print marker370at this stage can be used to mark the print. The folded side gusset film280is further transported in transverse direction290through an index nip380into cutter390where the folded side gusset film280is cut into side gusset pieces95such that the length of the side gusset pieces95is not more than the width of the top half30or bottom half40of the panel plastic film10.

In order to enlarge the initial gap created by the film slitter90between the top half30and bottom half40of the panel plastic film10, as shown inFIG. 3A, top timing belt600and bottom timing belt610are used that are positioned transversely on the machine such that the top half30and bottom half40of the panel plastic film10contact the teeth660of the timing belts600and610. The teeth660of the top timing belt600mesh with the teeth on the sprockets620and640on either ends. Similarly, the teeth600of the bottom timing belt610mesh with the teeth on the sprockets630and650on either ends. The relative positioning of the top timing belt600and bottom timing belt610is such that the outer toothless surfaces thereof are contacting each other substantially the entire length and width of the timing belts600and610. In other words, the bottom part of the top timing belt600is substantially fully in contact with the top part of the bottom timing belt610. The top half30of the panel plastic film10is in contact with the teeth660of the top timing belt600on the bottom part and the bottom half40of the panel plastic film10is in contact with the teeth660of the bottom timing belt610on the top part. Thus, the gap between the top half30and bottom half40of the panel plastic film10will be substantially same as the thicknesses of the bottom part of the top timing belt600and the top part of the bottom timing belt610including the heights of the teeth660thereon.

Now, the side gusset pieces95at the stage when the gap between the top half30and bottom half40is enlarged, is ready to be placed between the said top half30and bottom half40of the panel plastic film10. Transfer assembly400further transports side gusset pieces95for placement of the side gusset pieces95between top half30and bottom half40of the panel plastic film10. The length of the side gusset pieces95is generally less than the width of the top half30or bottom half40. The length of the side gusset piece95is such that the leading end of the side gusset pieces reach the far edge of the top half30and bottom half40; however, the trailing end remains inside the edge of the top half30and bottom half40. The indexing of the side gusset pieces95is timed in accordance with the width of plastic pouch260. For example, for a wider plastic pouch260, the indexing of side gusset pieces95would be done at a slower rate so that the side gusset pieces95are placed between top half30and bottom half40further apart from each other. Similarly, for a narrower plastic pouch260, the indexing of the side gusset pieces95will be done at a faster rate so that when the side gusset pieces95are placed between top half30and bottom half40, the distance between them will be smaller.

As described hereinabove, the length of side gusset pieces95can be same as the width of top half30and bottom half40; however, the length is so chosen that it is generally shorter than the width of top half30or bottom half40leaving a small portion of the top half30and bottom half40that will not be in contact with side gusset pieces95. This small portion without such contact would be generally on the side where the side gusset pieces95are transversely transported from.

FIG. 5shows the transformation of side gusset film280into side gusset pieces95and placement of side gusset pieces95between top half30and bottom half40of the panel plastic film10without showing most of the components or parts of the machine. Thus, side gusset film280after getting unwound from unwinding reel270is folded into folded side gusset film330having the combined width of the top front folded portion335and top rear folded portion336substantially the same as that of the bottom portion of the folded side gusset film330.

The folded side gusset film330gets cut into side gusset pieces95. The free edges of the top folded portions335and336will not be in contact with each other and there will be a longitudinal gap333between the said edges. The side gusset pieces95will be transported in transverse direction290and later on will be transported in the longitudinal direction50together with the top and bottom halves30and40respectively. The thin and flat space at the end of the side gusset piece95defined by the bottom edge334, the edge335aof the top front folded portion335, and the edge336aof the top rear folded portion336subsequently takes the shape similar to a rhomboid in which the front corner96and rear corner98will become part of a somewhat generous radius as described hereinafter. The front fold331is formed between the top front folded portion335and the bottom portion of the side gusset piece95. Similarly, the rear fold332is formed between the top rear folded portion336and the bottom portion of the side gusset piece95.

Now referring toFIG. 6A, the side gusset pieces95are transversely sealed using a heat sealer100such that at least the free edges of the front folded portion335and the rear folded portion336get sealed with the bottom surface of the top half30and the corresponding middle of the bottom portion gets sealed with the top surface of the bottom half40. The seal405extends beyond the length of the side gusset pieces95as can be seen in the said figure so that when the top half30and bottom half40are pulled away from each other, the side gusset pieces95also get opened up transforming the otherwise thin and flat space at the end into a shape similar to a rhomboid having rounded corners at the front and rear. In other words, the free edges of the top front folded portion335and the top rear folded portion336that are sealed with the bottom surface of top half30will move with top half30and the corresponding middle of the bottom portion of the side gusset pieces95sealed with the top surface of the bottom half40will move with the bottom half40. With such action of pulling away the top half30and the bottom half40, the thin and flat space of the side gusset pieces95at the end will become substantially a rhomboid shape space with the corners97and99together forming the top corner of the rhomboid shape with the seal405and the corners96and98forming the front and rear rounded corners of the rhomboid shape. The bottom corner105would be formed at the location of the middle of the bottom portion of the side gusset piece95with the seal405(not shown) for the bottom portion. The top corners97and99of the rhomboid shape would be stuck with the top half30and the corresponding bottom corner105of the side gusset piece95of the rhomboid shape would be stuck with the bottom half40. This is illustrated in greater detail inFIG. 6Bthat also shows dotted line415that divides in half the folded portion36of the top half30and folded portion46of the bottom half40. As can be seen in theFIG. 6B, the bottom edge334now assumes a different shape from the flat shape it originally had. Now, the bottom edge334is transformed into edge334aand334bwith the bottom corner105at the location where the seal405took place. The front fold331and rear fold332at this end of the side gusset pieces95turn into radius and as a result, the front and rear corners96and98respectively also become part of this generous radius. In other words, the opening resembles the shape of a rhomboid except for the two generous radii where the front and rear corners96and98are located. The free edges of the top front folded portion335and the top rear folded portion336are no longer free because of the seal405and therefore, the top corner97and99become together the top corner of the rhomboid-like shape. The rhomboid-like shape will have a vertical axis416.

At this stage, a pair of rollers (not shown) are brought in contact with the end of side gusset piece95such that contact of front corner96with the roller pushes the said front corner96rearwards and similarly, contact of rear corner98pushes the said rear corner98forward. Thus, the rollers push the said front corner97and rear corner98inwards into the rhomboid shaped cross sectional gap of the side gusset piece95so as to form another rhomboid shape of the end of the side gusset piece95with parts of the end of the side gusset piece95folded in the manner described. Now referring toFIG. 6C, the rhomboid shaped end410of the side gusset piece95shows the moved front corner96and rear corner98to be substantially along the vertical line416.FIG. 6Calso shows newly created front corner96A along the front fold331and rear corner98A along the rear fold332. Thus, on either side of the vertical line416, there will be parallel vertical edges, on the front of the vertical line416the vertical edge formed by edge335aof the top front folded portion335and edge334awhich was part of the bottom edge334. The moved front corner96lies exactly in the middle of this front vertical edge where the longitudinal dotted line415passes. Similarly, on the rear of the vertical line416, there will be a vertical edge formed by edge336aof the top rear folded portion336and edge334bwhich was part of the bottom edge334. The moved rear corner98lies exactly in the middle of the rear vertical edge where the longitudinal dotted line415passes. The slight distance on either side of the vertical axis416is the result of the thickness of the seal405on the top and bottom of the side gusset pieces95.

As can be seen, longitudinal dotted line415divides into substantially equal top and bottom halves the rhomboid shaped end410. Since the side gusset pieces95shown in the said figure are shorter in length than the width of top half30and bottom half40, slight portion35of the top half30will be there between the top corners97and98and the edge of to half30and likewise, slight portion45of the bottom half40will be there between the bottom corner105and the edge of the bottom half40.FIG. 6C, which is a side view of the side gusset pieces95having rhomboid shaped ends410being transported in longitudinal direction50. Sectional view at Section A-A of the top and bottom halves30and40respectively of the panel plastic film10and the side gusset piece95having the rhomboid shape end410is shown inFIG. 6E. The top half30is shown bent upwards with the folded portion36projecting beyond the top corners97and99and the bottom half40is shown bent downwards with the folded portion46projecting beyond the bottom corner105.

FIG. 7shows a diagrammatic perspective representation of the transformation of the bottom gusset film430into bottom gusset sealed with the panel plastic film10as well as the side gussets95. As shown in the said figure, there is provided an unwinding reel420from which bottom gusset film430gets unwound in transverse direction435. Bottom gusset film430passed through capstan nip440goes around accumulator roller450and passes through another capstan nip460. The bottom gusset film430is further transported through guide rollers470and480in the transverse direction435. The bottom gusset film430is transported around turn bar500which changes the direction as well as orientation of the bottom gusset film430. Due to the positioning of turn bar500, the transversely transported bottom gusset film430gets reoriented to be transported in longitudinal direction50such that the edges of the bottom gusset film430remain horizontal, but in a plane perpendicular to the plane when the said bottom gusset film430was being transported transversely in transverse direction435. In other words, the reoriented bottom gusset film430is substantially perpendicular to the greater portions of the top half30and bottom half40. In this position, the bottom gusset film430is substantially in contact with the full faces rhomboid shaped ends410of the side gusset pieces95and also respectively the folded portion36of the top half30and folded portion46of the bottom half40including the slight portions35and45of the top half30and bottom half40.

As the top half30and bottom half40together with side gusset pieces95are further transported in longitudinal direction50, the folded portions36and46of the top half30and bottom half40, together with the rhomboid shaped ends410and the bottom gusset film430are also transported in the longitudinal direction50; however, the folded portions36and46of the top half30and bottom half40, together with the rhomboid shaped ends410and the bottom gusset film430pass through a pair of vertical guide rollers510. A vertical heat sealer530vertically seals along the vertical axis416of the rhomboid410extending the seal in upward direction beyond the top corners97and99to the top edges of the bottom gusset film430and folded portion36of the top half30and in downward direction beyond the bottom corner105to the bottom edges of the bottom gusset film430and folded portion46of the bottom half40. Thus, vertical seal540seals the bottom gusset film430with the rhomboid shaped ends410of the side gusset pieces95and also respectively the folded portions36and46of the top half30and bottom half40.

After the vertical seal540, the top half30and bottom half40together with side gusset pieces95are further transported in longitudinal direction50, the folded portions36and46of the top half30and bottom half40, together with the rhomboid shaped ends410and the bottom gusset film430are also transported in the longitudinal direction50; however, the folded portions36and46of the top half30and bottom half40, together with the rhomboid shaped ends410and the bottom gusset film430pass through another pair of vertical guide rollers540.

FIG. 8Ashows the reoriented bottom gusset film430in contact with the rhomboid shaped ends410and parallel to the folded portions36and46of the top half30and bottom half40respectively at section B-B and before section B-B: As can be seen, vertical seal540seals the bottom gusset film430with the rhomboid shaped ends410along the vertical line of the rhomboid and also with the slight portions35and45of the top half30and bottom half40respectively.FIG. 8B shows the transverse cross-section at section B-B showing the folded portions36and46of the top and bottom halves30and40respectively of the panel plastic film, the rhomboid shaped end of the side gusset piece, and the bottom gusset film.

The vertically sealed bottom gusset film430as described hereinabove is then collapsed along longitudinal dotted line415such that the location of the top corners97and99and that of the bottom corner105of the rhomboid shaped end410would be substantially same. In other words, viewing from the top, after the said step of collapsing, the ends of the sick gusset pieces95would be of triangular shape560. As can be understood, there will be a top triangular shape560and a similar bottom triangular shape560substantially overlying each other. The base of the triangular shape560would fall along, the longitudinal dotted line415.FIG. 9illustrates the above in greater detail.

The top and bottom halves30and40of the panel plastic film10with the side gussets95and the bottom gusset film430sealed as aforementioned, get transported further in longitudinal direction50through a pair of rollers570.

A longitudinal heat sealer140seals the top edge of the bottom gusset film430together with the edge of the top half30and the bottom edge of the bottom gusset film430with the edge of the bottom half40as shown inFIG. 10. Thus, there is a longitudinal seal240on the top as well as on the bottom. A transverse heat sealer160seals across the width of the top and bottom halves30and40of the panel plastic film10. The transverse seal240seals the top edge of the side gusset piece95with the top half30and the bottom edge of the side gusset piece95with the bottom half40. This transverse seal250takes place where transverse sealing405had already taken place; however, transverse seal250is a stronger seal than the transverse seal405. Thus, the transverse seal250essentially divides side gusset pieces95along the length of the side gusset pieces95. In other words, the plastic pouches260are essentially ready to be cut after the said longitudinal seal240and transverse seal250take place.

Next step is to cut using cutter200along the transverse seal250. Such cutting may be required more than one time. After such cut, plastic pouch260is produced.FIG. 11Ashows the plastic pouch260in partially expanded state andFIG. 11Bshows the plastic pouch260in fully expanded state.

BEST MODE OF PERFORMING THE PRESENT INVENTION

The machine in accordance with the present invention has been described in detail hereinabove; however, the best mode of performing the present invention is to have the feeding line for the panel plastic film on one side of the machine and to have the feeding lines for the side gusset and bottom gusset on the other side of the machine. The machine in accordance with the present invention will use only one accumulator in the longitudinal direction to reduce the number of parts and also to make the foot-print of the machine as small as possible.

In the best mode of performing the present invention, heat sealers are used which permit the sealing of the side gusset pieces95with the panel plastic film10and the sealing of the bottom gusset film430with the panel plastic film10as well as the side gusset pieces95, the reason being the choice of the material for the side gusset film. Due to the material chosen for the side gusset film280, due to heat, the side gusset film280will not have a tendency to stick to some portions of itself. Likewise, the material chosen for the bottom gusset film430is also such that it will not have a tendency to stick with portions of itself under heat.

As aforementioned, the machine and the method in accordance with the present invention use a panel plastic film10from a single unwinding reel15as opposed to the different sources for providing top half30and bottom half40of the panel plastic film10.

The panel plastic film10unwinding from the said unwinding reel15is longitudinally folded into top and bottom halves10and40respectively and is transported using a nip23in longitudinal or machine direction50. A slitter90slits the panel plastic film10along the longitudinal fold to cut the film into top and bottom halves30and40respectively. The top and bottom halves30and40respectively simultaneously get transported ensuring that any design common to the top and bottom halves30and40respectively will always accurately match. The machine in accordance with the present invention, because of this unique feature of providing the top and bottom halves30and40respectively from folding the panel plastic film10unwound from a single unwinding reel15, requires only a single accumulator roller70.

The slitting of the top and bottom halves30and40respectively by the slitter90creates an initial gap between the top and bottom halves30and40respectively of the panel plastic film10. The said gap is enlarged by a top timing belt600and a bottom timing belt610that are part of transfer assembly400positioned transversely such that the bottom portion of the top timing belt600is substantially in contact with the top portion of the bottom timing belt610. The said timing belts600and610have teeth660on the inside. The teeth660of the top timing belt600mesh with the teeth on the sprockets620and640on either side. Similarly, the teeth660of the bottom timing belt610mesh with the teeth on the sprockets630and650on either side. The top half30of the panel plastic film10passes through the top timing belt600such that the bottom surface of the top half30of the panel plastic film10is in contact with the top of the teeth660on the lower portion of the top timing belt600. Similarly, the bottom half40of the panel plastic film10passes through the bottom timing belt610such that the top surface of the bottom half40of the panel plastic film10is in contact with the top of the teeth660on the top portion of the bottom timing belt610. Thus, the gap between the top and bottom halves30and40respectively of the panel plastic film10will be substantially equal to the total of the thicknesses of the top and bottom timing belts600and610including the heights of the teeth660on both the timing belts600and610. The enlargement of the gap at this stage is required to allow insertion of the side gusset pieces95between the top and bottom halves30and40respectively of the panel plastic film10.

Side gusset film280is unwound from an unwinding reel270and is guided by a nip285to be directed to an accumulator roller300. The side gusset film280exits a nip310and gets folded by a folding device320such that the folded portions are on the top and the total width of the top folded portions335and336is substantially same as the width of the bottom portion of the side gusset film280. The side gusset film280is further transported in transverse direction290and a creasing device340ensures that the front and rear folded edges331and332respectively maintain their crease. The side gusset film280exiting the creasing device340is directed by a pair of guide rollers345to another accumulator roller350. The side gusset film280is further transported in transverse direction290going around a tail feed360. There is provided a print mark sensor370which senses print or design registration of the side gusset film280. The side gusset film280gets further transported in the transverse direction290through an index nip380and gets cut into side gusset pieces95by a cutter390. The rate of indexing depends on the positioning of the side gusset pieces95between the top and bottom halves30and40respectively of the panel plastic film10. In other words, the width of the plastic pouch260will determine how far apart the side gusset pieces95are positioned between the top and bottom halves30and40respectively of the panel plastic film10which in turn determines the rate of indexation. Therefore, the wider the plastic pouch260, the slower will be the rate of indexation and vice versa. The length of the side gusset pieces95will not be more than the width of the top and bottom halves30and40respectively of the panel plastic film10and generally, the length will be shorter than the width of the top and bottom halves30and40respectively of the panel plastic film10. The side gusset pieces get inserted between the top and bottom halves30and40respectively of the panel plastic film10through the said enlarged gap.

A transverse heat sealer100seals the side gusset pieces95with the top and bottom halves30and40respectively of the panel plastic film10. The seal is along the length of the side gusset pieces95sealing the free edges of the top folded portions335and336respectively with the top half30of the panel plastic film10and the corresponding middle of the bottom portion of the side gusset piece95with the bottom half40of the panel plastic film10.

The next stage is to give the ends of the side gusset pieces95the shape of a rhomboid. The top half and the bottom half30and40respectively of the panel plastic film10are pulled away from each other. This action opens the side gusset pieces95in such a way that the cross-section of the space inside the side gusset pieces resembles a rhomboid like shape having a rounded corner96on the front folded edge331as well as a rounded corner98on the rear folded edge332of the side gusset piece ends. Using a roller (not shown), the said front rounded corner96is pushed inwards near the vertical axis416of the rhomboid shaped space and similarly, using another roller (not shown), the rounded rear corner98is also pushed inwards to be near the said vertical axis416. This action transforms the end of the side gusset pieces95into rhomboid shaped ends410that will now have a new front corner96aon the front folded edge331and a new rear corner98aat the rear folded edge332. Also, it will have top corners97and99at the seal405and a bottom corner105at the seal405.

The pulling action of the top and bottom halves30and40respectively of the panel plastic film10will result into a folded portion36of the top half30and similarly, a folded portion46of the bottom half40of the panel plastic film10. The folded portions36and46are relatively small in size compared to the remaining greater portions of the top and bottom halves30and40respectively and are generally perpendicular to the remaining greater portions of the top and bottom halves30and40respectively of the panel plastic film10.

The edge of the folded portion36of the top half30will project beyond the top corners97and99of the rhomboid shaped ends410and likewise, the edge of the folded portion46of the bottom half40will project beyond the bottom corner105of the rhomboid shaped ends410. In other words, the combined height of the folded portions36and46respectively of the top half30and the bottom half40of the panel plastic film10will be greater than the height of the rhomboid shaped ends410.

Bottom gusset film430unwinding from and unwinding reel420is transported in transverse direction435and is directed to go around an accumulator roller450using a nip440positioned before and a nip460after the said accumulator roller450. The bottom gusset film430is further transported in the transverse direction435using two separate guide rollers470and480. There is provided a turn bar500which changes the direction as well as the orientation of the bottom gusset film430which gets reoriented to be now transported in longitudinal direction50such that the edges of the bottom gusset film430remain horizontal, but in a plane perpendicular to the plane when it was being transported transversely. In this position, the bottom gusset film430would be substantially parallel to the rhomboid shaped ends as well as the folded top and bottom portions36and46respectively of the panel plastic film10. The bottom gusset film430at this stage is substantially in contact with the full faces of the rhomboid shaped ends410as also the folded top and bottom portions36and46respectively of the top and bottom halves30and40respectively of the panel plastic film10.

The next stage is to vertically heat-seal the bottom gusset film430with the rhomboid shaped ends410along the vertical axis416of the rhomboid shaped ends410of the side gusset pieces95. The bottom gusset film430also gets sealed with the top and bottom folded portions36and46respectively of the top and bottom halves30and40respectively of the panel plastic film10where the top and bottom folded portions36and46respectively project above and below the top corners97and99and the bottom corner105of the rhomboid shaped ends410.

The top and bottom halves30and40respectively of panel plastic film10together with side gusset pieces95and the vertically sealed bottom gusset film430with the rhomboid shaped ends410as well as the folded portions36and46of the top and bottom halves30and40respectively of panel plastic film10get further transported in longitudinal direction50. The bottom gusset film430with the rhomboid shaped ends410as well as the folded portions36and46respectively of the top and bottom halves30and40respectively of panel plastic film10pass through an index nip550.

The next step is to collapse the bottom gusset film430with the rhomboid shaped ends410as well as the folded portions36and46respectively of the top and bottom halves30and40respectively of panel plastic film10such that the rhomboid shaped ends410have the top corners97and99substantially contacting the bottom corner105resulting in a triangular top part and a triangular bottom part. At this stage, the top and bottom edges of the bottom gusset film430also would be substantially in contact with each other as well as the edge of the top portion36and the edge of the bottom portion46also would be substantially in contact with each other. It can be seen that at this stage, the folded portions36and46respectively of the top and bottom halves30and40respectively of the panel plastic film10get unfolded.

The so collapsed top and bottom halves36and46respectively of the panel plastic film10together with side gusset pieces95and the bottom gusset film430with the rhomboid shaped ends410as well as the folded portions36and46respectively of the top and bottom halves30and40respectively of panel plastic film10get further transported in longitudinal direction50and are ready for final longitudinal and transverse sealing before getting cut into pouches260.

A longitudinal heat sealer140seals the top edge of the bottom gusset film430with the edge of the top half30of the panel plastic film10and simultaneously, in a reciprocating action, the bottom edge of the bottom gusset film430gets longitudinally sealed with the edge of the bottom half40of the panel plastic film10.

A transverse heat sealer160seals the top edge of the side gusset pieces95with the edge of the top half30of the panel plastic film10in a reciprocating action, the bottom edge of the side gusset pieces95get sealed with the bottom half40of panel plastic film10.

The transverse sealing also seals the front collapsed edge of the bottom gusset film430with the corresponding collapsed edge of the side gusset piece95in the front. Similarly, the rear collapsed edge of the bottom gusset film430gets sealed with the corresponding collapsed edge of the side gusset piece95in the rear.

The next step is to cut along the transverse seal250and more than one cut may be required to produce plastic pouches260having two side gussets and one bottom gusset.

The principle of operation of the machine in accordance with the present invention as also the invented method of producing plastic pouches with two side gussets and one bottom gusset has been described in detail hereinabove can be applied with some variations in the machine which contains numerous components and the method which involves several steps.

As a person skilled in the art will readily understand from the detailed description of the present invention, merely because some changes may be made to the machine or to the method disclosed hereinabove without departing from the spirit and scope of the present invention, so modified machine or method should not be construed to fall outside the scope of the present invention as disclosed and claimed herein. All matters disclosed hereinabove or as shown in the accompanying drawings ought to be interpreted as illustrative and not in a limiting sense.

The following claims are intended to cover all of the generic and specific features of the present invention described hereinabove and all the statements of scope of the present invention regardless of the grammatical or linguistic variations might be said to fall therebetween.