A GUIDE MECHANISM FOR BAG FILM HAVING FASTENER ELEMENTS AND A FORM, FILL AND SEAL PACKAGING APPARATUS

Abstract: A guide mechanism is disclosed for providing uninter­ rupted guidance of a reclosable bag through a filling station in a form, fill and seal apparatus. The apparatus includes the guide mechanism (30) which is positioned outside of and be­ tween a pair of plies (18, 19) of the bag film through the filling station. The guide mechanism includes a first guide (102) for engaging the bottom of the bag film and a second guide (109) for engaging interlocked fastener elements on the opposing plies of the bag film. A separating device (80, 32) is positioned along the path traveled by the bag film for separating the in­ terlocked fastener elements as the bag film is advanced.

Description: This invention relates to a mechanism for guiding a continuous film web of a plastic material having reclosable fastener elements on respective opposing plies of the film web, and more particularly to a mechanism for guiding and separating the interlocked fastener elements extending along the edges of the film web. The invention also relates to a form, fill and seal packaging apparatus employing the guide mechanism. Bags of various types have been used for packaging a wide variety of products such as, for example, cereals, cookies, potato chips and the like. These bags can serve as the external package for the products, or can be inserted into boxes as a liner for the boxes. When packaging perishable products such as cereal, cookies and potato chips, the bags should be sealed to preserve the product contained therein by preventing the co-mingling of outside air and moisture with the product in the bags. Conventional sealed bags (such as most cereal bags and potato chip bags) have seals which are formed by gluing together or heat sealing together a pair of opposed edges of the bags. One problem with such conventional sealed bags is that they cannot be resealed after being opened. Thus, once the bag is opened, the user cannot prevent the unwanted intrusion of outside air and moisture into the bag. Usually, reclosable bags include a pair of fastener elements (such as a pair of rib and groove profiles), which the user fastens together after opening to thereby effectively seal the contents of the bag from the intrusion of unwanted air and moisture. One example of such a reclosable or "zippered" bag is the ZIPLOC® brand food storage bag manufactured by The Dow Chemical Company. Both conventional and reclosable bags share a common feature in that they are usually formed from a continuous roll of a film web. This film web is folded over to form a pair of opposing plies forming a generally tubular structure which can be filled with a product. The tubular web is then subdivided transversely into a plurality of individual bags. Machines for forming and filling such bags from a continuous film web are known. U.S. Patent No. 3,815,317 (Toss) relates to a form, fill and seal apparatus for use with zippered bags. A continuous web of film is fed to the apparatus. The continuous web has interlocked fastener profiles. The profiles are disengaged, and the film spread apart to remove wrinkles. A pin unlocks the profiles, while a guide device holds the profiles apart. The profiles are rejoined as they are pinched by closing rolls. The interlocked film is then cross-sealed and filled through the remaining open side. The final seam is then sealed and severed to provide the final structure. It should be noted that the mechanisms in the Toss structure which unlock and reclose the profiles do so for the purpose of removing wrinkles or folds from the film. The filling of the bag itself is accomplished through an open side of the bag. During the filling of the bag, the profiles are closed. U.S. Patent Nos. 4,024,010 and 4,094,729 (Boccia) relate to an apparatus wherein two opposing film layers with interlocking rib and groove profiles on opposing faces are separated so that a heat sealing of the side seams can be accomplished only in those areas where the profiles remain interlocked. A separating finger opens the interlocked fastener elements. Grooves on the top and bottom of the separating finger are provided for maintaining the profiles elements in alignment. One difficulty encountered in bag forming, filling and sealing operations resides in maintaining the film web from which the bags are cut in a proper lateral alignment as the film web travels through the machine. This problem is especially acute in the forming, filling and sealing of reclosable bags having fastener elements. The term "bag film" herein denotes a film web having fastener elements positioned along their edges. Typically, a bag film is wound on a roll in a helical pattern, such that the fastener elements of adjacent layers on the roll are offset laterally from each other. The bag film is usually wound on a roll in this manner in order to form a roll having a more constant diameter throughout its width. If the bag film were not wound in this helical manner, the extra thickness provided by the fastener elements would cause the bag film roll to be much thicker in that area wherein the fastener elements are placed. The helical winding of the bag film makes it difficult, however, to draw the bag film from the roll in a proper lateral alignment for entry into the forming, filling and sealing machine. As the bag film should be properly laterally aligned before the bag film is fed into the machine, means should be provided for laterally aligning the bag film prior to the bag film being fed into the forming, filling and sealing portions of the machine. It is therefore an object of this invention to provide a guide mechanism for providing uninterrupted guidance of a reclosable bag film having interlocked fastener elements extending along the edges of the film web. The guide mechanism is positioned inside of and between a pair of opposing plies of a folded-over film web for providing uninterrupted guidance of the bag film through a forming station. The guide mechanism comprises a first guide which engages an interior surface of the bag film and a second guide which engages a pair of interlocked fastener elements on the opposing plies of the bag film. A separating means is positioned along the path traveled by the bag film for separating the interlocked fastener elements as the bag film is advanced. A support arm is provided for supporting the first and second guides and the separating means. It is a further object of the present invention to provide a form, fill and seal packaging apparatus comprising means for supplying a continuous bag film having reclosable fastener elements on respective opposing plies of the film web, and means for feeding the bag film through a filling station for supplying a predetermined amount of a product to the bag film. Guide means are provided immediately preceding the filling station and positioned inside the bag film for providing uninterrupted guidance of the bag film through the filling station. A separating means precedes the filling station for separating the interlocked fastener elements. The packaging apparatus also includes means for pressing the fastener elements together in an interlocking relationship and means for laterally sealing the bag film to form a bag assembly having first and second side seams. Means are also provided for severing the bag assembly from the film. Preferably, the guide means includes a support arm and a bracket member connected to the support arm and disposed between the plies of the film web. A first guide wheel is rotatably coupled to the bracket member for engaging an interior surface of the bag film, and a second guide wheel is rotatably coupled to the bracket member for engaging the fastener elements. The separating means can comprise a separating edge which is disposed on the support arm. Thus, a feature of the present invention is that a guide mechanism is provided which is disposed in the interior of the folded-over plies of the film web between the bottom of the web (i.e., the bight) and the interlocked fastener elements of the film web. By being placed inside the film web between the bottom and the interlocked fastener elements, the guide mechanism can properly laterally align the bag film so that the film is correctly placed for the feeding into the filling portion of the packaging machine. In a preferred embodiment of the present invention the guide mechanism can include a first rotatable guide wheel for engaging the bottom of the film (i.e., the bight) and a second rotatable guide wheel for engaging the fastener elements. The use of guide wheels has the advantage of providing a relatively frictionless engagement (in the direction of the path of travel of the film) between the guide mechanism and the wheel. This relatively frictionless engagement reduces the guide mechanism's drag on the film. This reduction in drag is especially helpful in facilitating high speed packaging processes. It is also a preferred embodiment of the present invention that the support arm for supporting the guide mechanism immediately follows the guide wheels, and that the support arm includes the means for separating the interlocked fastener elements. By positioning the guide wheels so that they precede the separating means, the guide wheels can engage the two opposed, inner surfaces of the bag film. This inner surface engagement of the film has the advantage of providing an effective means for laterally aligning the film. The placement of the separating means on the support arm serves the dual functions of 1) supporting the guide wheels and 2) disengaging the interlocked fastener elements to permit the passage of a filling chute between the profiles. Additional advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of a preferred embodiment exemplifying the base mode of carrying out the invention as presently perceived. Figure 1 is a perspective view of the form, fill and seal packaging apparatus of the present invention; Figure 2 is a top plan view of the guide mechanism of the present invention; Figure 3 is a side view of the guide mechanism of the present invention; and Figure 4 is an exploded view of the guide mechanism of the present invention. A form, fill and seal packaging machine (apparatus) is shown in Figure 1. A roll of bag film 10 for supplying a continuous web 16 of the film is supported on a spindle 12 which is rotatably journaled on a rack 14 for maintaining the roll 10 above the ground. The continuous web 16 of film is unwound from the roll 10 and is fed into the packaging apparatus 8. The web 16 is helically wound onto the roll 10, and as drawn from the roll 10 has a pair of opposed film plies 18, 19. The opposed film plies 18, 19 are continuous with each other at the bottom edge 20 (of the finished bag 21) and are interlocked near the top edge 22 (of the finished bag 21) by fastener elements comprising a female profile 24 which is formed as a part of ply 18 and a male profile 26 which is formed as a part of ply 19. The fastener elements 24, 26 can be similar to the fastener elements found on ZIPLOC® brand food storage bags manufactured by The Dow Chemical Company. The fastener elements 24, 26 permit the finished bag 21 to be reclosed after opening. From the roll 10, the web 16 is drawn upwardly over a roller 28 by a feed mechanism (not shown) which is disposed downstream in the path of travel of the web 16. Although roller 28 is shown as a single roller, it preferably comprises a "dancer roll" system. The web 16 is then drawn through a guide mechanism 30 which includes means for laterally aligning the web 16 and a splitting edge 32 for disengaging the interlocked fastener elements 24, 26. An idler roller 36 is disposed directly downstream of the path of travel of the web 16 from the guide mechanism 30. The idler roller 36 is positioned at about the same vertical height as the guide mechanism 30 and is rotatably journaled on a spindle 38. After the fastener elements 24, 26 have been disengaged by the splitting edge 32, both plies 18, 19 of the web 16 pass over the idler roller 36. Once the web has passed over the idler roller 36, the web 16 travels generally vertically downwardly as indicated by arrow A. Due to the action of the splitting edge 32, the fastener elements 24, 26 are disengaged as the web 16 passes over idler roller 36 and begins its downward travel. A side arm filling station comprising a feed chute 40 is provided for directing a product, such as cereal flakes or pellets 42, into the interior of the bag web 16. The feed chute 40 includes a generally vertically extending upper portion 44, an angled median portion 46 and a generally vertically extending lower portion 50. The angled portion 46 passes between the disengaged fastener elements 24, 26 and into the interior of the web 16. The lower portion 50 is disposed between the plies 18, 19 of the web 16. A steering, joining and closing mechanism 54 for pressing together and reinterlocking the fastener elements 24, 26 of the opposed plies 18, 19 is disposed in the path of travel of the web 16 and is positioned directly downstream of the angled portion 46. More particularly, the mechanism 54 is disposed downstream of that portion of the angled portion 46 of filling chute 40 which passes between the fastener elements 24, 26. Although the mechanism 54 is disposed downstream of the angled portion 46, it is also disposed at the same general point in the direction of travel of the web 16 as a portion of the lower portion 50 of the feed chute 40. A reciprocally moving, generally vertically extending seal forming bar 56 is disposed downstream of the mechanism 54. The bar 56 is provided for forming a temporary "peel seal" 58. In the finished bag 21, the peel seal 58 is formed interiorly of and generally parallel to the fastener elements 24, 26. The peel seal 58 can be unsealed by the user without destroying the integrity of the finished bag 21. The peel seal 58 helps to make the finished bag 21 more tamper resistant. Preferably, the length of the bar 56 is approximately equal to the width of the finished bag 21. A reciprocally moving, generally horizontally disposed seal forming means 60 having sealing bars 60a and 60b is disposed below the open lower end 62 of the feed chute 40. Preferably, seal forming means 60 is disposed at a distance from the open lower end 62 of the feed chute 40 which is approximately equal to the width of one finished bag 21. Sealing bars 60a and 60b are provided for laterally sealing together the first and second plies 18, 19 to form the side seals of the finished bag 21. A severing means 66 is disposed between sealing bars 60a and 60b and is provided for severing the intermittently sealed continuous web 16 into individual finished bags 21. The guide mechanism 30 of the present invention is more clearly shown in Figures 2 to 4. The mechanism 30 includes a support arm 74 for supporting the various components of the guide mechanism 30. The support arm 74 can be connected to a portion (not shown) of the form, fill and seal packaging apparatus 8, can be supported by an independent stand (not shown) or can be formed to include an integral stand (not shown). The support arm 74 includes a portion 76 disposed exteriorly of the film web, a portion 78 disposed interiorly of the film web 16 and an intermediate portion 80. The intermediate portion 80 is disposed in the path of travel of the fastener elements 24, 26 and passes between the fastener elements of the film web 16 as the web is advanced. An upper bracket member 84 and a lower bracket member 86 are attached by screws 87 to the respective upper surface 88 and lower surface 90 of the interior portion 78 of the support arm 74. The bracket members 84, 86 are disposed in a plane generally parallel to the plies 18, 19 of the film web and extend generally upstream in the direction of travel of the web 16 from the support arm 74. The bracket members 84, 86 each include a beveled peripheral lip 92 which extends along the forward and side edges of the bracket members 84, 86. The beveled lips 92 facilitate the passage of the plies 18, 19 over the bracket members 84, 86, and reduce the likelihood of the plies 18, 19 becoming snagged on the respective bracket members 84, 86. Each of the bracket members 84, 86 also include a first rounded forward corner 98 and a second rounded forward corner 100. The rounded corners 98, 100 and the beveled lip 92 combine to form the guide mechanism 30 which is tapered about all web contacting edge peripheries. This dual tapering helps to prevent the plies 18, 19 from becoming snagged on the guide mechanism 30. A first guide wheel 102 is rotatably journaled on an axle 104 to both the upper and lower bracket members 84, 86 and is disposed therebetween. The axis about which the first guide wheel 102 rotates is generally perpendicular to the plane of the plies 18, 19 of the film web 16. The first guide wheel 102 is sized and positioned so that its film engaging surface 106 engages the bottom 109 of the interior surface of the film web 16. A second guide wheel 109 is rotatably journaled on an axle 110 to both the upper and lower bracket members 84, 86 and is disposed therebetween. The axis about which the second guide wheel 109 rotates is parallel to the axis about which the first guide wheel 102 rotates, with both being perpendicular to the plane of the plies 18, 19 of the film web 16. The second guide wheel 109 is sized and positioned so that its film engaging surface 112 engages the interior surface 114 of the fastener elements 24, 26 while they are interlocked. The second guide wheel 109 preferably exerts a sufficient force against the interior surface 114 of the fastener elements 24, 26 to align the film web 16 properly, without putting enough force on the interior surface 114 of the fastener elements 24, 26 to cause the fastener elements to become disengaged. The film engaging surfaces 106, 112 of the guide wheels 102, 109 are best shown in Figures 2 and 4 as being beveled surfaces each of which include a relatively larger beveled surface 115 and a relatively smaller right cylindrical surface 116. Although rounded or squared off film engaging surfaces can be used, beveled film engaging surfaces 106, 112 enhance the performance of the first and second guide wheels 102, 109 and especially enhance the performance of the second guide wheel 109. It has been found that the beveled film engaging surface 112 can exert a relatively greater force against the interior surface 114 of the fastener elements 24, 26 without disengaging the fastener elements than a rounded or squared off film engaging surface. The applicants have also found that the best results are obtained by placing the larger surface 115 against the fastener element (female profile) 24. In one testing session, the applicants found that by placing the fastener element 24 against the larger beveled surface 115, the fastener elements 24, 26 could withstand an average of 18.8 pounds of force (84 N) without becoming disengaged. When the fastener element (male profile) 26 was placed against the larger beveled surface 115, the fastener elements could withstand an average of 9.3 pounds of force (41.4 N) without becoming disengaged. When a rounded film engaging surface (i.e., without guide wheels) (not shown) was employed, the applicants found that the fastener elements 24, 26 could withstand an average of 9.8 pounds of force (43.6 N) without becoming disengaged. This ability of a beveled film engaging surface to exert increased force helps the guide mechanism 30 to perform its function of laterally aligning the film web 16 without disengaging the fastener elements 24, 26. Although a beveled film engaging surface 106 can be used with the first guide wheel 102, the configuration of the film engaging surface 106 of the first guide wheel 102 is not as important to the performance of the guide mechanism 30 as the configuration of the film engaging surface 112 of the second guide wheel 109. Preferably, the guide wheels 102, 109 are constructed of a material such as stainless steel. In an alternate embodiment (not shown) the guide wheels 102, 109 can be eliminated and the bracket members 84, 86 can be sized and positioned to serve as a stationary edge means for aligning the film web. In such an embodiment, the first forward corners and sides of the bracket members would engage the bottom 106 of the interior surface of the film, and the second forward corners and sides of the bracket members would engage the interior surface 114 of the fastener elements. Similar to bracket members 84, 86, the bracket members of this alternate embodiment should have a corner and edge configuration which provides the guide mechanism with a forward portion tapered about an axis both parallel and perpendicular to the plane of the plies 18, 19 of the film web 16. The splitting edge 32 is formed as a part of the intermediate portion 80 of the support arm 74, and comprises the forward edge 118 of the support arm 74 being beveled on its upper and lower surfaces. Alternatively, the splitting edge 32 can comprise a separable beveled member (not shown) which is mounted to the intermediate portion 80 of the support arm 74. In operation, the engagement of the first guide wheel 102 with the bottom surface 108 of the film web 16 and the engagement of the film engaging surface 112 of the second guide wheel 109 with the interior surface 114 of the fastener elements 24, 26 cooperate to place the bag film 16 in its proper lateral alignment. The rotatability of the guide wheels 102, 109 performs this lateral alignment with a relatively small amount of frictional engagement, thus reducing the drag of the guide mechanism 30 on the film web 16. After the second guide wheel 109 engages the interlocked fastener elements 24, 26 to laterally align the film web 16, the fastener elements 24, 26 are advanced to engage the splitting edge 32, whereby they are disengaged. In this manner, it is possible to utilize the interlocked fastener elements 24, 26 to laterally align the film web 16 and to separate the fastener elements after film web 16 has been aligned. It has been found by applicants that the system described above provides an efficient guiding and splitting mechanism for a forming, filling and sealing apparatus for zippered bags. Having described the invention in detail, and by reference to the preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.

Claims: 1. A guide mechanism for providing uninterrupted guidance of a reclosable bag film having interlocked fastener elements, said guide mechanism (30) being positioned inside of and between a pair of opposing plies (18, 19) of a folded-over web (16) of a bag film for providing uninterrupted guidance of said bag film through a forming station, said guide mechanism (30) comprising: a first guide (102) engaging an interior surface of said bag film and a second guide (109) engaging a pair of interlocked fastener elements (24, 26) on said opposing plies of said bag film, separating means (32) positioned along the path traveled by said bag film for separating said interlocked fastener elements (24, 26) as said bag film is advanced, and a support arm (74, 80) for supporting said first and second guides (102, 109) and said separating means (32). 2. The mechanism of Claim 1, including a bracket member (84, 86) connected to said support arm (74, 80), and wherein said first guide (102) and a second guide (109) comprise first and second guide wheels rotatably mounted on said bracket member (84, 86). 3. The mechanism of Claim 2, wherein said first guide wheel (102) engages an interior surface of said bag film (16) and said second guide wheel (109) has a beveled surface (112) for engaging the interlocked fastener elements (24, 26) on opposing plies (18, 19) of said bag film, said first and second guide wheels (102, 109) having an axis of rotation generally perpendicular to the faces of said bag film. 4. A form, fill and seal packaging apparatus comprising: means for supplying a continuous plastic bag film (16) in a tubular configuration having interlocked reclosable fastener elements (24, 26) on respective opposing plies (18, 19) of said film; means for feeding said film (16) through a filling station (40) for supplying a predetermined amount of product to said bag film; a guide mechanism (30) immediately preceding said filling station and positioned inside said bag film (16) for providing uninterrupted guidance of said film through said filling station, said guide mechanism (30) comprising: a separating means (32) for separating said fastener elements (24, 26), a support arm (74, 80) for supporting said guide mechanism (30) and said separating means (32); means (54) downstream of said filling station for pressing said fastener elements (24, 26) together in an interlocking relationship; means (60) for laterally sealing said bag film (16) to form a bag assembly (21) having first and second side seams; and means (66) for severing said bag assembly from said bag film. 5. The apparatus of Claim 4, wherein said guide mechanism (30) includes a first edge means (102) for engaging an interior surface of said bag film opposite said fastener elements (24, 26) and a second edge means (109) for engaging said fastener elements. 6. The apparatus of Claim 5, wherein said first and second edge means (102, 109) comprise first and second stationary edge means, each having a tapered forward portion. 7. The apparatus of Claim 5, wherein said first edge means (102) comprises a first guide wheel having an axis generally perpendicular to the plane of the bag film, and said second edge means (109) comprises a second guide wheel having an axis generally perpendicular to the plane of said film. 8. The apparatus of Claim 7, wherein said first guide wheel (102) engages an interior surface of said bag film and a second guide wheel (109) engages said fastener elements (24, 26), said second guide wheel (109) having a beveled fastener element engaging surface (112). 9. The apparatus of Claim 8, wherein said support arm (74, 80) immediately follows said guide wheels (102, 109) and includes said separating means (32) extending between the fastener elements (24, 26) and a bracket member (84, 86) connected to said support arm (74, 80) for rotatably supporting said guide wheels (102, 109). 10. The apparatus of Claim 7, wherein said first and second guide wheels (102, 109) each include a beveled surface (106, 112) having an axis generally perpendicular to the plane of the bag film. 11. The apparatus of Claim 7, wherein said separating means (32) comprises a separating edge (118) disposed on said support arm (74, 80) and wherein the first and second guide wheels (102, 109) are positioned to immediately precede said separating edge.

Inventors: BEHR, R., DOUGLAS, ZIEKE, LARRY, M.
Applicants: THE DOW CHEMICAL COMPANY
Application year: 1987
Main classification: B65B9
IPC codes: B65B9