PACKAGING APPARATUS INCLUDING ROTARY JAW DEVICE AND METHOD OF MAKING PACKAGES |
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申请号 | EP11743542.0 | 申请日 | 2011-08-12 | 公开(公告)号 | EP2603434B1 | 公开(公告)日 | 2014-10-15 |
申请人 | Frito-Lay Trading Company GmbH; | 发明人 | TILLEY, Mark; | ||||
摘要 | A packaging apparatus including a rotary jaw device, the rotary jaw device comprising an elongate holder, an elongate knife mounted on and projecting outwardly from the elongate holder, the knife having an elongate cutting edge parallel to a plane of the knife, and at least one part of a heat seal device located on the elongate holder on opposed sides of the knife. A packaging method is also disclosed. | ||||||
权利要求 | |||||||
说明书全文 | The present invention relates to packaging apparatus including a rotary jaw device and to a method of making packages. It is known to employ vertical form, fill, and seal (VFFS) packaging apparatus to produce packages, in the form of bags, pillow packs or pouches of products, such as snack foods. A tubular film, having been formed from a roll of packaging film of heat sealable plastic material which has been longitudinally sealed, is fed intermittently through a jaw device. The film forms a flattened tube at the jaw device. The jaw device forms a pair of vertically spaced hermetic heat seals extending transversely across the tube, the seals being located between vertically adjacent packages. The jaw device also cuts through a middle portion, located between the hermetic seals, extending across the tube which separates a lower sealed package containing the packaged product from an upper unsealed package. In this way, a lower hermetic seal forms the upper seal of the lower package, and an upper hermetic seal forms the lower seal of the upper package. The upper package is then filled with product, the tube is advanced downwardly through the jaw device, and then the cycle is repeated when the upper edge of the upper package, and the lower edge of the following package, is disposed between the jaws of the jaw device. There are several known principles of operation of such jaws of a vertical, form, fill, and seal (VFFS) packaging apparatus. One class of jaw devices utilises a continuous rotary jaw motion, which is illustrated with reference to Referring to The knife 12 and the anvil 16 both rotate in phase and in opposite rotational directions as shown by the arrows in The knife 12 is rotated about an axis X orthogonal to the longitudinal direction L of the tube 14 and parallel to the surface of the anvil 16 and the cutting edge 20 of the blade 18. Although not illustrated, plural knives 12 may be mounted about a common shaft disposed along axis X and mutually angularly separated, so that for each cycle of rotation of the common shaft, plural cuts are made by respective knives 12. Plural anvils 16 would be correspondingly provided. As also shown in The lower portion of the knife 12 is received in an elongate recess 30 in the elongate holder 21 and securely fixed therein. The cutting action of the knife 12 is progressive, so that during the continuous rotation of the knife 12 in holder 21, initially one longitudinal end 22 of the knife 12 first contacts the anvil 16 and subsequently the contact point therebetween progresses along the cutting edge 20 of the blade 18 towards the other longitudinal end 24 of the knife 12. To achieve such progressive cutting action, as shown in Elongate heat seal devices 26, 28 are disposed either in the anvil 16 and/or in the elongate holder 21 for the knife so that transverse hermetic seals 32, 34 are formed in the flattened tube 14 on opposite sides of the transverse cut 36 made by the knife 12. The heat seal devices 26, 28 may take a number of forms, typically transversely extending mating ridges and grooves formed in the opposed surfaces of the anvil 16 and the elongate holder 21. As shown in The known rotary jaw device provides an effective heat sealing and cutting mechanism, which reliably forms hermetic seals at the opposite ends of a package and with adjacent packages being reliably separated by the action of the knife. However, there is an increasing need for product manufacturers to reduce the amount of packaging material associated with their products, and in particular not only to reduce packaging costs but also to reduce the carbon footprint, expressed in tonnes of carbon dioxide emissions, of the packaging material and/or the packaging operation. The known rotary jaw device forms hermetic seals which are rather wide, in the longitudinal direction of the tube, and also there is material wastage between adjacent hermetic seals, because a portion of the film material of the tube which is cut through by the rotary cutting action of the knife must be provided between the adjacent hermetic seals. Accordingly, there is a need in the art for a rotary jaw device for a packaging apparatus, and to a method of making packages, which can permit the amount of packaging material to be reduced, together with the associated packaging costs and carbon footprint, i.e. carbon dioxide emissions, while still achieving effective hermetic seals at the opposite ends of a package. The present invention aims at least partially to meet this need. The present invention accordingly provides a packaging apparatus according to claim 1. Typically, the cutting edge extends along a centre of the knife. In one embodiment the knife has a thickness of from 1 to 3mm, optionally about 2mm. The pressure strip may comprise a strip of elastic resilient material. The rotary jaw device may further comprise an anvil mounted in opposition to the elongate holder, so that the elongate holder and the anvil comprise opposed jaws of the rotary jaw device, the anvil having a reaction surface for the cutting action of the knife. Preferably, the knife and anvil are mutually arranged so that as the knife rotates by rotation of the elongate holder, the cutting edge of the knife progressively contacts the reaction surface with a contact point therebetween moving longitudinally along the cutting edge. Optionally, the anvil comprises a heater for heating the reaction surface. Typically, the rotary jaw device is adapted for forming pillow packs of film material, optionally the packs packaging snack food. The present invention further provides a method according to claim 9. Optionally, the cutting edge extends along a centre of the knife. Typically, the knife has a thickness of from 1 to 3mm, optionally about 2mm. The pressure strip may comprise a strip of elastic resilient material. Preferably, the cut edge of each package is 0.5 to 1.5mm, typically about 1mm, from the heat seal. Preferably, the hermetic seal has a width of from 1 to 4 mm, optionally 1 to 2 mm. Typically, the packages are pillow packs of film material, optionally the packs packaging snack food. Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:
In the jaw device 110 of The knife 112 is rotated about an axis X orthogonal to the longitudinal direction L of the tube 114 and parallel to the surface of the anvil 116 and the cutting edge 120 of the blade 118. The jaw device 110 is mounted about the axis, for example to a shaft disposed along the axis, by a mounting support 111. As shown particularly in The lower portion of the knife 112 is received in an elongate recess 130 in the elongate holder 21 and securely fixed therein. The cutting action of the knife 112 is progressive, so that initially one longitudinal end 122 of the knife 112 first contacts the anvil 116 and subsequently the contact point progresses along the cutting edge 120 of the blade 118 towards the other longitudinal end 124 of the knife 112. To achieve such progressive cutting action, as shown in Elongate heat seal devices 126, 128 are disposed either in the anvil 116 and/or in the elongate holder 121 for the knife so that transverse hermetic seals 132, 134 are formed in the flattened tube 114 on opposite sides of the transverse cut 136 made by the knife 112. In the device of the illustrated embodiment, the anvil 116 is a heated block, and elongate pressure strips 126, 128, for example of elastic and resilient material such as heat-resistant rubber, are disposed on respective opposed sides of the knife 112. The knife 112 and the pressure strips 126, 128 stand proud of the mounting surface 138 of the elongate holder 121. The elongate pressure strips 126, 128 are parallel to the knife 112, and accordingly the elongate pressure strips 126, 128 are also mounted at an angle P to the longitudinal direction of the elongate holder 121. The knife 112 and the pressure strips 126, 128 are therefore inclined at the angle P to the longitudinal sides of the elongate holder 121 which is orthogonal to the longitudinal direction L. Thus, when the longitudinal direction is oriented vertically, knife 112 and the pressure strips 126, 128 inclined at the angle β to the horizontal. As the rotary contact progresses, the whole width of the flattened tube 114 is not cut through simultaneously, but instead point contact of the knife blade 118 transitions across the tube 114 as the rotary action progresses. The pressure strips 126, 128 locally press the film material of the tube 114 against the heated anvil 116 to form two spaced hermetic seals 132, 134. Typically, the width of the knife (dimension a in In contrast, in the known device of Instead of providing a parallel-mounted knife with an inclined blade as in the known device, the device of the present invention provides an inclined mounting for a knife with a parallel central blade. The elongate pressure strips 126, 128 are parallel to the knife 112 and so the entire assembly of the knife 112 and the elongate pressure strips 126, 128 on opposite sides thereof is mounted at an inclination to the longitudinal direction of the elongate holder 121. The provision of elongate pressure strips 126, 128 of elastic resilient material which are urged against a rigid heated anvil, which has a planar surface, provides the advantage of a high strength seal of minimum width. The pressure strips 126, 128 can exert a high pressure over a small surface area, providing an enhanced heat seal as compared to providing a lower pressure seal over a greater width. Therefore a narrower heat seal can provide improved hermetic performance and durability as compared to a wider seal. Typically, the entire width of the assembly of the knife 112 and the elongate pressure strips 126, 128, all inclined to the longitudinal direction of the elongate holder 121 is 8 mm, whereas in the known device the entire width of the assembly of the knife 12 and the heat seal devices 26, 28, all parallel to the longitudinal direction of the elongate holder 21 is 20 mm. The result of this change of structure and orientation of the knife is shown in Therefore for each package produced in accordance with this embodiment of the invention there is a typical total film material saving of 3mm in length without having any impact of the security of the heat seal. This material saving is achieved by reducing the amount of unsealed material at the ends of the packages that has no functional purpose with respect to forming a hermetic seal. In addition, the heat seal can be narrower than known heat seals by using the specific pressure strips against the heated anvil, providing even greater packaging material savings. Typically, the heat seal has a width of from 1 to 4 mm, optionally 1 to 2 mm. Such a film material saving has potentially enormous impact on high volume production of products such as snack foods. The Applicant and its related companies form part of one of the largest snack food companies in the world, and it is estimated that this packaging material saving cumulatively amounts to a global cost saving in packaging material of many tens of millions of dollars per annum, and, importantly, a saving of approximately 16 thousand tonnes of carbon dioxide production per annum. This invention therefore may yield very significant reductions in the carbon footprint of the packaging of a wide variety of products, particularly snack foods. It will be clear to a person skilled in the art that the angle and dimensions exemplified above are merely indicative of an angle size and dimensions that may be used in accordance wit the present invention, and that these parameters may be varied depending upon a number of factors, including package size, shape and dimensions. The jaw device and method may be used to produce primary packages of a variety of products, of which snack foods are only a preferred example. The jaw device and method may also be adapted to produce secondary packages, for example multi-pack packaging. As described above for the known device, in the device of the invention plural knives may be mounted about a common shaft disposed along the rotational axis and mutually angularly separated, so that for each cycle of rotation of the common shaft, plural cuts are made by respective knives, and corresponding plural packages are separated by the cutting action for each rotational cycle of the shaft. Plural anvils would be correspondingly provided. In alternative embodiments, the heat seal devices may be crimping devices and/or the one or both sides of the entire assembly, namely the elongate holder and/or the anvil, may be heated. Furthermore, elongate heat seal devices may be disposed either in the anvil and/or in the elongate holder for the knife. |