This application relates generally to methods and apparatus for shrinking of a heat shrinkable film wrapped around a product, and more particularly to methods and apparatus for shrinking selected portions of the film adjacent end seams formed by the film wrap, using an intermittent motion of the products.
A product is typically wrapped in a heat shrinkable film by a process which results in forming an end seam by the application of heat transversely between sequential products. The film is then generally shrunk. The film around each wrapped product has a leading transverse end seam and a trailing transverse end seam. The shrinking is usually done by the application to the film of a heated fluid, typically a gas such as air or steam or a liquid such as water. This shrinking step is mainly undertaken in order to improve the appearance of the final package by the removal of wrinkles in the film.
A particularly important class of products for which film shrinking is needed is that of packaged food products, especially poultry parts. It is common to package poultry parts by (i) placing the poultry parts in a molded tray having a stiffening flange around its upper periphery and (ii) wrapping the tray and its contents in a heat shrinkable film. The film is then shrunk. There are certain problems inherent in packaging poultry parts in film which make the shrinking step particularly demanding in order to achieve a relatively smooth appearance. One of the problems is that the transverse end seams formed in the wrapping process typically extend outwardly beyond the tray flange after being sealed; it is desired to cause the sealed end seam to be hidden under the tray flange after shrinking. Another problem is that in cases where the height of the poultry product is greater than twice the height of the flange of the tray, the formed transverse end seams are higher than the flange. This situation makes shrinking the end seams so as to draw each end seam into a position under the flange especially difficult. Furthermore, the seam end portions at each package corner are frequently left extended after the film is shrunk so as to be visible beyond the package contours.
Government regulations require the marking of food storage and preparation information on the film. This marking is generally best done on the portion of film which is to be in contact with the bottom of the tray. If this film portion is shrunk by the direct application of heat, the printing frequently becomes distorted and difficult to read, thus not meeting the legibility standards set by the regulations.
Among the numerous prior patents which address the process of film shrinking are U.S. Pat. No. 5,193,290; U.S. Pat. No. 5,398,427; U.S. Pat. No. 5,546,677; and U.S. Pat. No. 5,787,682. The '290 and '427 patents disclose general film shrinking inventions and provide useful background. The '677 patent is directed to causing heat to be applied to the transverse seams of the film without directly heating the bottom film portion. The '677 patent discloses an invention in which the tray is turned 90° to travel “sideways” on its conveyor to facilitate end seam shrinkage. The '682 patent discloses an invention in which the tray is not turned sideways and moves continuously along a conveyor, with nozzles located below the conveyor. The nozzles are arranged to travel back and forth below the conveyor and their travel is timed such that the heated fluid from the first nozzle heats only the leading seam and the heated fluid from the second nozzle heats only the trailing seam. This arrangement, though effective, tends to be costly to manufacture and operate due to the need to move the nozzles during the process.
It would be desirable to provide a machine that does not require the packages to be turned sideways, that effectively shrinks portions of film at the end seams and that can be produced and operated in a more cost effective manner.
In one aspect, a method for shrinking selected spaced apart portions of film wrapped around a series of products of similar dimension being conveyed by a conveyor along a path in a selected direction is provided. The method involves the steps of: (a) indexing the conveyor and stopping the conveyor; (b) while the conveyor is stopped, causing heated fluid to flow from one or more nozzles so that a first heated fluid flow impinges upon selected portions of film in the vicinity of a product leading edge and a second heated fluid flow impinges upon selected portion of film in the vicinity of a product trailing edge; (c) repeating steps (a) and (b) multiple times so that, for multiple instances of the product, selected portions of film along both trailing and leading edges of each instance of the product are caused to shrink. In one example, the flow of heated fluid is stopped during at least part of step (a).
In one example of the method of the preceding paragraph, in step (a) the conveyor is indexed by a set distance; in step (b), the product trailing edge is a trailing edge of a first instance of the product along the conveyor and the product leading edge is a leading edge of a second instance of the product along the conveyor, where the second instance of the product is upstream of the first instance of the product and is the next instance of the product along the conveyor.
In one example of the method of either of the two preceding paragraphs, a single nozzle produces both the first heated fluid flow and the second heated fluid flow.
In one example of the method of any of the three preceding paragraphs, each product has a similar first dimension in a direction parallel to selected direction, and the set distance is substantially the same as the first dimension plus a predefined gap spacing between products being conveyed along the path.
In one example of the preceding method aspect, in step (a) the conveyor is indexed by a set distance; in step (b), the product trailing edge is a trailing edge of a first instance of the product and the product leading edge is a leading edge of the first instance of the product.
In one example of the method of the preceding paragraph, a first nozzle produces the first heated fluid flow and a second nozzle produces the second heated fluid flow.
In one example of the method of either of the two preceding paragraphs, each product has a similar first dimension in a direction parallel to selected direction, and the set distance is substantially the same as the first dimension plus a predefined gap spacing between products being conveyed along the path.
In one example of the preceding method aspect, in step (a) the conveyor is indexed until an instance of the product is detected to be in a suitable position for treatment by heated fluid flow.
In one example of the method of the preceding paragraph, a photo-detector is used for detection purposes.
In one example of the method of either of the two preceding paragraphs, the product trailing edge is a trailing edge of a first instance of the product and the product leading edge is a leading edge of the first instance of the product.
In another aspect, a method for shrinking selected spaced apart portions of film wrapped around a product that is one of a series of products of similar dimension being conveyed by a conveyor along a path in a selected direction is provided. The method involves the steps of: (a) based upon a first dimension of the products, locating a hot air nozzle at a specific position along the path, where the first dimension runs parallel to the selected direction; (b) in relation to a given instance of the product on the conveyor: (i) indexing the conveyor by a set distance that moves an edge of the product into position such that heated fluid exiting the nozzle will impinge upon selected portions of film in the vicinity of the edge; (ii) stopping the conveyor after indexing by the set distance; (iii) when the conveyor is stopped, causing heated fluid to flow from the nozzle to impinge upon the selected portions of film; (iv) thereafter indexing the conveyor by the set distance.
In one example, the nozzle is configured to provide both a first heated fluid flow and a second heated fluid flow; during step (b)(i): the given instance of the product is moved so that its trailing edge is in position such that the first heated fluid flow will impinge upon selected portions of film in the vicinity of the trailing edge; and a following instance of the product is moved so that its leading edge is in position such that the second heated fluid flow will impinge upon selected portions of film in the vicinity of the leading edge of the following instance of the product; during step (b)(iii), both the first heated fluid flow and second heated fluid flow are produced.
In one example, during step (b)(iv): the given instance of the product is moved away from the nozzle; the following instance of the product is moved so that its trailing edge is in position such that the first heated fluid flow will impinge upon selected portions of film in the vicinity of the trailing edge of the following instance of product; and a next following instance of the product is moved so that its leading edge is in position such that the second heated fluid flow will impinge upon selected portions of film in the vicinity of the leading edge of the next following instance of the product; the conveyor is stopped after indexing by the set distance; following step (b)(iv): when the conveyor is stopped, producing both the first heated fluid flow and the second heated fluid flow.
In one example, in step (a) the nozzle is positioned further downstream along the path for increasing size of the first dimension.
In one example, the set distance is substantially the same as the first dimension plus a predefined gap spacing between products being conveyed along the path.
In one example, the nozzle is a first nozzle, a second nozzle is spaced apart from the first nozzle by a distance corresponding to the first dimension; during step (b)(i): the given instance of the product is moved so that (1) one of its trailing edge or its leading edge is in position so that heated fluid exiting the first nozzle will impinge upon selected portions of film in the vicinity of the one edge and (2) the other of its trailing edge or its leading edge is in position so that heated fluid exiting the second nozzle will impinge upon selected portions of film in the vicinity of the other edge.
In one example, during step (b)(iv): the given instance of the product is moved away from both the first nozzle and the second nozzle; a following instance of the product is moved so that one of its trailing edge or its leading edge is in position so that heated fluid exiting the first nozzle will impinge upon selected portions of film in the vicinity of the one edge of the following instance of the food product; and the following instance of the product is moved so that the other of its trailing edge or its leading edge is in position so that heated fluid exiting the second nozzle will impinge upon selected portions of film in the vicinity of the other edge of the following instance of the food product; the conveyor is stopped after indexing by the set distance; following step (b)(iv): when the conveyor is stopped, producing both the first heated fluid flow and the second heated fluid flow.
In one example, in step (a) position of both the first nozzle and the second nozzle are set based upon the first dimension.
In one example, the position of the second nozzle is fixed and in step (a) only the position of the first nozzle is set based upon the first dimension.
In one example, in step (b)(iii) the heated fluid is caused to flow for a set time period or a set amount of heated fluid flow, and is thereafter stopped.
In a further aspect, a method for shrinking selected spaced apart portions of film wrapped around a product which is one of a series of products of similar dimension being conveyed by a conveyor along a path in a selected direction, said method comprising the steps of: (a) based upon a first dimension of the products, locating a first hot air nozzle at a specific position along the path, where the first dimension runs parallel to the selected direction, a second hot air nozzle also being located along the path and spaced from the first hot air nozzle; (b) in relation to a given instance of the product on the conveyor: (i) indexing the conveyor until the product is detected to be in a position such that heated fluid exiting the first nozzle will impinge upon selected portions of film in the vicinity of one of a trailing or leading edge of the product and heated fluid flow exiting the second nozzle will impinge upon selected portions of film in the vicinity of the other of the trailing edge or leading edge of the product; (ii) stopping the conveyor after indexing; (iii) when the conveyor is stopped, causing heated fluid to flow from the first nozzle and the second nozzle to impinge upon the selected portions of film for a set time period or a set amount of heated fluid flow, and then stopping the heated fluid flow; (iv) thereafter indexing the conveyor until a next instance of the product is detected to be in a position suitable for treatment.
In another aspect, an apparatus for shrinking selected spaced apart portions of film wrapped around a series of products of similar dimension includes a conveyor for conveying the products along a path in a selected direction. One or more fluid nozzles are position below the path for selectively outputting a heated fluid flow. A controller is configured to operate the apparatus so as to carry out the steps of: (a) indexing the conveyor and stopping the conveyor with product at a desired location; (b) while the conveyor is stopped, causing heated fluid to flow from the one or more nozzles so that a first heated fluid flow impinges upon selected portions of film in the vicinity of a product leading edge and a second heated fluid flow impinges upon selected portion of film in the vicinity of a product trailing edge; (c) stopping the flow of heated fluid; (d) repeating steps (a) through (c) multiple times so that, for multiple instances of the product, selected portions of film along both trailing and leading edges of each instance of the product are caused to shrink.
Generally, a method for shrinking selected spaced apart portions of film wrapped around a product that is one of a series of products of similar dimension being conveyed by a conveyor along a path in a selected direction is provided The method involves: (a) based upon a first dimension of the products, locating a hot air nozzle at a specific position along the path, where the first dimension runs parallel to the selected direction; and (b) in relation to a given instance of the product on the conveyor: (i) indexing the conveyor by a set distance that moves an edge of the product into position such that heated fluid exiting the nozzle will impinge upon selected portions of film in the vicinity of the edge; (ii) stopping the conveyor after indexing by the set distance; (iii) when the conveyor is stopped; (iv) thereafter indexing the conveyor by the set distance. In certain embodiments, the heated fluid is caused to flow for a set time period or a set amount of heated fluid flow, and is thereafter stopped, or in some cases reduced, until a next product is moved into position.
Moreover, a method for shrinking selected spaced apart portions of film wrapped around a series of products of similar dimension being conveyed by a conveyor along a path in a selected direction is provided. The method involves: (a) indexing the conveyor and stopping the conveyor; (b) while the conveyor is stopped, causing heated fluid to flow from one or more nozzles so that a first heated fluid flow impinges upon selected portions of film in the vicinity of a product leading edge and a second heated fluid flow impinges upon selected portion of film in the vicinity of a product trailing edge; (c) repeating steps (a) and (b) multiple times so that, for multiple instances of the product, selected portions of film along both trailing and leading edges of each instance of the product are caused to shrink. In certain embodiments, the flow of heated fluid is stopped, or at least reduced, during all of step (a) or at least part of step (a).
Referring now to the embodiment of
The direction of movement of the portion of the conveyor 12 with product thereon is left to right as indicated by arrow 22. The position of the nozzle 13 is set according to a dimension of the product in the direction that is parallel with direction 22. By way of example, in
Thus, in the embodiment of
As seen in
In the embodiment of
Referring now to the embodiment of
In the embodiment of
Referring to the embodiment of
It is to be clearly understood that the above description is intended by way of illustration and example only, is not intended to be taken by way of limitation, and that other changes and modifications are possible.
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Entry |
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PCT, International Search Report and Written Opinion, International Application No. PCT/US2014/011600 (dated May 12, 2014). |
Number | Date | Country | |
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20140202117 A1 | Jul 2014 | US |
Number | Date | Country | |
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61756282 | Jan 2013 | US |