Patent Publication Number: US-5893256-A

Title: Packaging apparatus

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a packaging apparatus and, in particular, an apparatus for making filter paper bags containing infusable products such as tea, coffee or chamomile. 
     The use of filter paper bags, referred to more simply as tea bags, for making infusions has become widespread throughout the world because they are so handy and easy to use. 
     The increasing world-wide popularity of tea bags has led distributors of tea and other infusable products to invest huge resources into research targeted to improving tea bag design and ease of use. 
     This research has aimed to improve tea bag forms, the ease with which the product is released into the liquid during infusion, shelf life, ease of packaging the tea bags into their final containers and so on. 
     Over the years, the original single-lobed tea bag, with pick-up thread and tag has been replaced by the now well-established two-lobed tea bag (still with pick-up thread and tag and with or without individual overwrap). The two-lobed tea bag is made from a piece of tubular filter paper filled with two charges of infusable product each in a separate pouch. The two pouches are then folded over each other so that there is a larger surface area in contact with the liquid thus allowing the two charges of product inside the pouches to infuse more effectively. 
     A more recent market development has been the possibility of making tea bags which, after infusion, that is to say, at the moment they are removed from the liquid, can be squeezed in order to wring as much liquid as possible from the bag and also to prevent the liquid from dripping while the bag is being disposed of. 
     This squeeze feature allows the user to make the most of that part of the infusion (usually containing a high concentration of product) which is normally lost when the tea bag is removed from the pot and thrown away. The squeezing action is achieved by pulling the thread which typically attaches the tea bag to the tag. At present, the squeeze feature is applied to single-lobed tea bags, as disclosed, for example, by international patent publications N. WO-94/22721, or N-WO-95/10461 and WO-95/10462 or N. WO-96/15033 and WO-95/27666. 
     Attempts have recently been made to apply the squeeze feature to the two-lobed, and more widely-used, tea bags as well. 
     To obtain two-lobed tea bags of this kind, it is necessary to provide tea bags with squeezing means that are practical and reliable for users and, at the same time, economical enough not to raise the unit cost of each tea bag. 
     In this regard, we refer to the two-lobed tea bag described in patent application N. WO-97/19005 where, between the two pouches which contain the product charges and whose opposite ends are joined to each other, there is a thread by which the tea bag can be held during infusion and which is attached to a first area at the bottom end of the bag and not forming part of the product pouches. The thread extends to a second area at the top end of the tea bag and again in the space between the two folded pouches. 
     The thread is looped in such a way that it forms a coil between the two pouches that does not protrude from the sides of the tea bag itself. The thread loop is attached to the said end areas. The thread is also attached to a tag which allows the user to pull it and thus squeeze the tea bag. 
     The squeezing action is enhanced by the fact that between the pouches the coil forms a cross which makes it easier to draw the opposite corners of the tea bag together. 
     SUMMARY OF THE INVENTION 
     The present invention has for an object to provide an apparatus capable of making two-lobed tea bags, with squeeze feature, rapidly and economically and of forming all the parts of the tea-bags with a high degree of precision. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The technical characteristics of the invention according to the above mentioned aim are described in the claims below and the advantages of the invention will become more apparent from the detailed description which follows, with reference to the accompanying drawings, which illustrate a preferred embodiment of the invention and in which: 
     FIGS. 1 and 2 illustrate a tea bag for infusable products made by the apparatus disclosed by the present invention and shown, respectively, in a state prior to use, with overwrap, and in an intermediate, pre-infusion state, these two figures being a schematic side view and a front view, respectively; 
     FIGS. 3 and 4 are a side view and a front view, respectively, of the tea bag shown in FIGS. 1 and 2 in the state it assumes during infusion. 
     FIG. 5 illustrates a piece of tubular filter paper, during a stage in the production of the tea bag illustrated in the above mentioned figures using the apparatus disclosed by the present invention; 
     FIG. 6 is a schematic front view, with some parts cut away in order to better illustrate others, of the apparatus for making the tea bag illustrated in the above mentioned figures; 
     FIG. 7 is a schematic, perspective view, with some parts cut away in order to better illustrate others, of a part of the apparatus shown in FIG. 6, namely, a product feed station and a second station equipped with folding and sealing means; 
     FIG. 8 is a schematic, front view, with some parts cut away in order to better illustrate others, of another part of the apparatus shown in FIG. 6, namely, a tea bag sealing and finishing station; 
     FIG. 9 is a scaled-up, schematic front view of a single folding substation of the station illustrated in FIG. 6. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in the accompanying drawings, with particular reference to FIGS. 1 to 5, the apparatus disclosed by the present invention makes two-lobed tea bags with squeeze feature. These tea bags consist essentially of two pouches 1 and 2, each containing a charge 5 of infusable product (for example, tea, coffee or chamomile) and made from a piece of tubular, heat-sealable filter paper. 
     These two pouches 1 and 2 are attached to each other at their corresponding, near ends 1a and 2a and folded over so as to join the free, opposite ends 1b and 2b and so that the pouches come face to face on their inner sides. A thread 3 is attached between these facing surfaces to permit the tea bag to be picked up during infusion. 
     The pick-up thread 3 is wound in a coil S between the two pouches 1 and 2 whose width is prevented from exceeding the width of the tea bag by retaining points (described in more detail below) at end areas of the pouches 1 and 2 and reaching as far as the top ends. 
     In the latter area (that is, at the top ends), the thread 3 is also attached to a tag 4 and both the thread and the tag are attached to the tea bag by a strip of filter paper forming part of the bag itself. The tag 4 is made in such a way that, once detached from the tea bag, it can be used not only in the usual manner, that is, to manipulate the bag during infusion, but also to permit the thread 3 to be pulled in order to squeeze the tea bag. In other words, pulling the thread 3 draws the ends of the pouches 1 and 2 together and thus squeezes liquid out of the tea bag. 
     As is clearly shown in FIG. 6, the apparatus used to make tea bags of the kind just described essentially envisages a plurality of stations (preferably seven in number) located one after the other along a feed line A. 
     The first station 6 feeds a continuous strip 7 of filter paper towards a product feed unit 8 (see also FIG. 7). The feed unit 8 (consisting of a hopper 8t and a doser 8d) places the product charges 5 at preset intervals on a defined area along the middle of the strip 7. 
     The strip 7 is drawn continuously by a motor-driven unwinding roller 40 from a roll 41 located upstream of the unwinding roller in relation to the feed line A. 
     Downstream of the unit 8 that feeds the product charges 5, there is envisaged a second station 9 which comprises means 10 designed to fold the free lateral edges 7ta and 7tb of the strip 7 over the product charges 5 placed on the strip itself. This forms a continuous tube 7t of filter paper that is half as wide as the original strip and that has a longitudinal center line X (see also FIG. 5). 
     As shown schematically in FIG. 7, the said folding means 10 may consist simply of a semicylindrical, horizontal guide (of known kind and therefore not illustrated in detail) located just after the product charge 5 feed unit 8 and operating in conjunction with a third station 11 which seals the strip 7 lengthwise. The third station 11 may consist of a pair of plates 42p (illustrated schematically in FIG. 6) placed on opposite sides of the guide which blow hot air onto the said free edges 7ta and 7tb of the strip 7. As the free edges 7ta and 7tb move forward, they pass through a pair of rollers 42, with vertical axes, placed side by side, which join the said free edges 7ta and 7tb together, thus forming a continuous sealed tube 7t with, along the middle of it, a seam line 7 parallel to the aforementioned center line X. 
     Still with reference to FIGS. 6 and 7, the next station, labeled 12, in the series of stations on the machine, is designed to seal the continuous tube 7t crossways in such a way as to close off each single product charge 5 at the front 7a and at the back 7p and to form individual pouches, each pair of which 1 and 2, will be used to make a two-lobed tea bag. 
     The fourth station 12 consists of a pair of opposing, motor-driven rollers 12a and 12b, with recesses 12s made in them to accommodate the product charges 5 and on both sides of which there are heaters 12r designed to seal the aforementioned front and rear areas 7a and 7p. 
     Downstream of the rollers 12a and 12b, there is a fifth station 13 equipped with means 14 for forming a path T followed by a heat-sealable thread 3, the path T being clearly visible in FIG. 5 and consisting of a consecutive series of sections T1, T2, T3, T4, T5, T6 and T7 arranged in a coil S. 
     The means 14, besides forming the path T, also permit the thread 3 to be placed on the free surface of the continuous tube 7t in such a way that the path T thus formed (meaning by path the said succession of sections T1 to T7) is placed on each pair of pouches 1 and 2. On each pair of pouches 1 and 2, the ends 3a and 3b of the thread 3 are laid on the corresponding front area 7a of each pouch 1 and 2 on opposite sides of the above mentioned center line X. 
     The means 14 that define the path followed by the thread 3 (which is unwound continuously) envisage a first roller 20 equipped with thread 3 positioning elements 21 and 21b. The first elements 21 can move along the surface of the first roller 20 so that they can go back under the surface of the roller 20 when the thread 3 is being laid down on the continuous tube 7t, whilst the second bar element 21b moves in the proximity of the said roller in order to guide the thread 3 around the first elements 21 and allow the thread 3 to wind its way along the sections T1, T2, T3, T4, T5, T6 and T7 making up the path T and to be laid in this form on the free surface of the pouches 1 and 2. 
     Above the roller 20, there is a unit 22 which feeds the (heat-sealable, continuous) thread 3 to the said roller. The unit 22 consists essentially of a fixed frame 22a which mounts one or more reels 22b with a tension roller 22c acting on them in order to keep the thread 3 on the roller 20 at the right tension. 
     The fifth station 13 is also equipped with localized heating means 15 at the above mentioned front and rear closed areas 7a and 7p of each pouch 1 and 2 so as to attach the thread 3 to the pouch 1 and 2 securely at the localized front and rear areas 7a and 7p. 
     As can also be seen in FIG. 6, the said heating means 15 consist of a second motor-driven roller 23 located under the plane made by the continuous tube 7t moving along the feed line A. 
     The second roller 23 is opposite the first roller 20 and has, on its lateral surface, a series of recesses 24 designed to accommodate the pouches 1 and 2 alternated with parts 25 equipped with heating elements designed to heat the front areas 7a and rear areas 7p of each pair of pouches 1 and 2 when the thread 3 is placed on the pouches. 
     The parts 25 of the second roller 23 are shaped in such way as to heat localized points of the front areas 7a and rear areas 7p of the pouches 1 and 2 and so that the thread 3 is sealed to the pair of pouches 1 and 2 at predetermined sealing points which define the sequence of sections T1, T2, T3, T4, T5, T6 and T7. 
     Two of the intermediate sections of thread thus formed, namely, the ones labeled T2 and T6, are at right angles to the center line X on corresponding front areas 7a of each pouch 1 and 2, forming corresponding points PA2 and PA6 where the thread 3 is temporarily accumulated and from which it can be detached from the said front areas. Each of these points PA2 and PA6 consists of a looped piece of thread 3 (see FIG. 5). Obviously, this configuration is defined by the means 14 described earlier. 
     Once the thread 3 has been laid on and sealed to the pouches 1 and 2, the tube 7t reaches a sixth station 16 which cuts it and the thread 3 crossways in such a way as to form a tea bag in a configuration that comprises the following: a pair of pouches 1 and 2 complete with a piece of thread 3 which is sealed to the said pouches at localized points on the front areas 7a and rear areas 7p and whose two ends 3a and 3b are placed on corresponding front areas 7a of each pouch 1 and 2 on opposite sides of the center line X (as clearly shown in FIG. 5). 
     The sixth station 16 consists essentially of a rotary knife 16c fitted to a roller 16r mounted on a frame 16s in such a way that it can rotate. 
     Downstream of the cutting station 16 there is a seventh station 17 equipped with folding means 18 and sealing means 26 to fold over and join the pouches 1 and 2 to each other at their free ends 1b and 2b defined by the corresponding front areas 7a of each pouch 1 and 2. In addition to the means 18 and 26, there are also envisaged means 19 designed to apply the tag 4 to the outermost parts 1b&#39; and 2b&#39; of the free ends 1b and 2b of the pouches 1 and 2 which include the above mentioned ends 3a and 3b of the thread 3. 
     The seventh station 17, illustrated in detail in FIG. 8, consists of a carousel 27 that rotates about an axis Y and that is equipped with a plurality of grippers 27b each designed to hold a pair of pouches 1 and 2 and to carry the latter to each of a plurality of substations located around the carousel itself where different operations are carried out. 
     The first of these substations, also illustrated in FIG. 9, has means 18 that fold the pouches 1 and 2 towards each other. The said means 18 consist of a pair of fixed guides 18a and 18b placed on both sides of a central recess 18c through which the tea bag is made to pass in a direction perpendicular to the feed line A. 
     This is done by a pair of levers 43a and 43b which pull and push the tea bag towards and away from the said recess 18c and are designed to pick up the said pair of pouches 1 and 2 and place them in one of the above mentioned grippers 27b folded in such a way that the two pouches 1 and 2 are face to face and with the thread 3 also attached to one of their surfaces. During the folding stage, the levers 43a and 43b also create, in known manner, thanks to their special shape (illustrated in FIG. 9) the typical concertina-like fold at the bottom ends 1a and 2a (shown in FIG. 1). 
     As the carousel 27 rotates (in the direction of the arrow F1 shown in FIGS. 8 and 9), the gripper 27b carries the tea bag to a second substation equipped with the above mentioned sealing means 26. The latter securely attach the two pouches 1 and 2 to each other at the innermost parts 1b&#34; and 2b&#34; of their free ends 1b and 2b, that is to say, the front areas 7a&#34; that protrude from the gripper 27b. 
     The sealing means 26 consist of an arm 26a, pivoted at one end and mounting a sealing plate 26b, and a counterplate 26c. The sealing plate 26b is shaped in such a way as to create a broken join line L1 (see FIGS. 2 and 4) leaving gaps for the sections T1 and T7 of the thread 3 in the above mentioned front areas 7a. 
     The carousel 27 continues to turn to carry the individual grippers 27b to a third substation 60 where the free ends of the tea bags are prescored. The third substation comprises a pair of opposing knives 61a and 61b designed to prescore the free ends 1b and 2b of the pouches 1 and 2 in such a way as to create a second weakened line 31 extending crossways with respect to the longitudinal line X through the center of the pouches 1 and 2. 
     Next, the carousel 27 carries the tea bag to a fourth substation equipped with other sealing means 19 where the tag 4 is applied to the outermost parts 1b&#39; and 2b&#39;, corresponding to the front areas 7a&#39;, of the free ends 1b and 2b of the pouches 1 and 2. 
     The fourth substation is connected to a first unit 34 (see also FIG. 6) that feeds a continuous strip of tags 4s. This feed unit 34 consists of a motor-driven roller 35 and first means 36 for conveying the said continuous strip to the said fourth substation. 
     Looking in more detail, there are means 19 which may consist of a scoring element 28a with a related counter-element 28e designed not only to cut off each single tag 4 but also to create a weakened line 29 through the center of the tag 4, before the tag 4 itself is applied to the pouches 1 and 2. The scoring elements 28a and 28e may be positioned after a pair of unwinding rollers 28b and 28c located upstream of the gripper 27b along the direction in which the strip 4s of tags 4 is fed. The cut-off and scoring elements 28a and 28e have alternating motion and are represented by a broken line in the drawings. 
     The means for creating the first weakened line 29 is not necessary on the apparatus if the continuous strip of tags 4 being used already has the said first weakened lines 29 made in it. 
     Between the gripper 27b and the scoring element 28a there is an arm 46 mounting at one end a sealing unit 47 used to apply the tag 4 to the joined ends 1b&#39; and 2b&#39; of the pouches 1 and 2. In order to correctly seal the tag 4, the latter is placed against a counterplate 62 which, as soon as sealing has been effected, also allows the tag 4 to be partially turned upwards (the upward turn being illustrated as a broken line in FIG. 8) as the carousel continues to rotate. 
     The latter rotating motion of the carousel carries each gripper 27b close to a fifth substation 30 where the tag 4 is folded and partially sealed to the tea bag. This substation comprises a pusher element 48, that acts on the surface of the tea bag on which the tag 4 is folded, and a sealing unit 49 acting on the opposite surface of the tea bag (both mounted on the same shaft but having independent drives). 
     The sealer unit 49 is shaped in such a way as to activate a part of the glue on a specific area of the tea bag so as to create a punctiform seal (or &#34;weak&#34; seal) firm enough to hold the tag 4 to the tea bag but such as to allow the user to detach the tag without tearing the tea bag. 
     In this way, the tag 4 is folded over so it is flat against and sealed to the side of a related pouch 2 (the direction of rotation is indicated by the arrow F in FIG. 1). 
     The pouches 1 and 2 and the tag 4 folded in this way can then be wrapped with a suitable overwrap 33 shown with a broken line in FIG. 1). 
     The apparatus disclosed may also envisage a second unit 37 (see FIG. 6 again) for feeding a continuous strip of tea bag overwraps 33s with the tags 4 incorporated in them. 
     The second unit 37 consists of a second motor-driven roller 38 and second means 39 for conveying the continuous strip 33s to the seventh station 17. 
     The seventh station separates each overwrap 33 from the continuous strip by known means which are not fully illustrated and uses it to wrap up the tea bag. 
     After this wrapping operation, the finished tea bags are fed to customary cartoning stations (not illustrated) for final packaging operations. 
     The apparatus disclosed by the present invention therefore achieves the above mentioned aims by providing a fast and reliable automatic tea bag apparatus consisting of a plurality of synchronized and relatively small stations making up a comparatively compact machine. 
     Moreover, the said stations make a two-lobed tea bag with an intricate thread system to provide an effective means of squeezing and have a high output capability: this makes for a superior quality product at a relatively low cost, thus providing a tea bag that is extremely competitive on the market. 
     The invention described can be subject to modifications and variations without thereby departing from the scope of the inventive concept. Moreover, all the details of the invention may be substituted by technically equivalent elements.