Adhesive bonding and miscellaneous chemical manufacture – Surface bonding means and/or assembly means therefor – Presses or press platen structures – per se
Reexamination Certificate
1997-09-03
2001-05-15
Ball, Michael W. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Surface bonding means and/or assembly means therefor
Presses or press platen structures, per se
C156S581000, C053S374400, C053S376200
Reexamination Certificate
active
06230781
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates in general to form, fill, and seal packaging machinery of the type in which a continuous sheet of a packaging material is sequentially folded about a series of articles to be packaged, hot or cold sealed about the articles, and cut into individually sealed packages. More specifically, this invention pertains to an improved crimper assembly for forming end seals in overlapping portions of the sheet of packaging material after being folded about an article.
The formation of a plurality of individually sealed packages of articles using a single continuous sheet of a packaging material is well known in the art. Briefly, the sheet of packaging material is initially passed through a folding mechanism, which continuously folds the film over on itself to form an enclosure for a series of spaces apart articles. The overlapping portions of the film are then sealed along a continuous longitudinal seal. Next, the folded sheet of packaging material is fed to a sealing and cutting assembly, which seals the leading and trailing edges of the package to be formed about the enclosed article and cuts the tube into a plurality of individually sealed packages. In some instances, it may be desirable to apply heat during the process of sealing the overlapping portions of packaging material. Packages produced by this form, fill, and seal process are commonly used for snack bars, candy, cereals, and the like, as well as for other non-food articles.
The sealing of the overlapping end portions of the sheet of packaging material is frequently accomplished by a mechanical crimper assembly. A conventional mechanical crimper assembly includes a pair of opposed crimpers which are disposed on opposite sides of the overlapping portions of the sheet of packaging material. The crimpers are provided with respective undulating or serrated crimping surfaces defined by adjacent peaks and valleys. When the opposed crimpers are moved into engagement with the overlapping portions of the sheet of packaging material, the peaks of the first crimping surface are aligned with the valleys of the second crimping surface, and vice versa. Such engagement compresses the overlapping portions of the sheet of packaging material to form an intermeshing seal pattern. In some instances, the sheet of packaging material is provided with a cohesive coating for accomplishing the seal when compressed. In other instances, an intermediate seal layer of a coating or other bonding material is provided.
During the crimping and sealing process, it is important that the crimpers exert a sufficient amount of force to compress the overlapping portions of the sheet of packaging material. If an insufficient amount of force is exerted by the crimpers, then the overlapping portions of the sheet of packaging material will not be compressed sufficiently to form a complete seal. At the same time, however, it is equally important that the amount of force exerted by the crimpers not exceed the strength of the sheet of packaging material. If an excessive amount of force is exerted by the crimpers, the sheet of packaging material will tear or break. Thus, it is desirable that the amount of force which can be exerted by the crimpers against the overlapping portions of the sheet of packaging material remain within a predetermined range to insure a complete and secure seal.
In a conventional crimper assembly, the crimpers and the crimping surfaces have been formed from a strong, rigid material, such as high strength steel. Although such crimpers have functioned satisfactorily in the past, several drawbacks have been noted. First, in order to insure that the amount of force exerted by the crimpers against the overlapping portions of the sheet of packaging material remains within the predetermined desired range, the initial set-up of the crimpers on the crimping assembly must be performed very carefully. This time consuming operation must be repeated whenever it is desired to change from one film thickness to another and, therefore, is inefficient. Second, wrinkles which are occasionally present in the sheet of packaging material can cause additional overlapping portions to be compressed between the opposed crimpers. Because of the rigid nature of the crimpers, the presence of the wrinkles results in an excessive amount of force being applied to the overlapping portions of the sheet of packaging material. Third, in some packages, the number of overlapping layers of the sheet of packaging material varies from side to side. This can occur when the package being formed includes a longitudinally extending fin seal which is folded(d to one side. Each of the two end seals of the package would thus include a smaller thickness region (composed of only two overlapping portions of the sheet of packaging material) and a larger thickness region (composed of four overlapping portions of the sheet of packaging material). Similar varying thickness regions are found in packages containing conventional gusset folds and fin seals. It has been found to be quite difficult to set-up the two crimpers so as to exert a proper amount of force against these different thickness regions of the end seals. Although it is known to form the crimpers with bowed or recessed areas to accommodate the larger thickness region, such crimpers are more expensive and still suffer from the other drawbacks mentioned above. Thus, it would be desirable to provide an improved structure for a crimper assembly which addresses all of these drawbacks.
SUMMARY OF THE INVENTION
This invention relates to an improved structure for a crimper assembly for use in a form, fill, and seal apparatus for sealing overlapping portions of a sheet of packaging material after being folded about a plurality of articles. The crimper assembly includes upper and lower crimper bars which are supported for rotation about axes which extend generally perpendicular to the movement of the sheet of packaging material. A pair of upper crimpers are secured to opposite sides of the upper crimper bar, while a pair of lower crimpers are secured to opposite sides of the lower crimper bars. Each of the upper crimpers includes a metallic base having an outwardly facing portion with an undulating cross sectional shape. A slot is formed in the outwardly facing portion of the upper crimper, and a cutting blade is retained therein. In a first embodiment, an insert is secured to the base of each of the upper crimpers. The insert includes a rigid shank having a lip portion extending therefrom. Portions of the outer surface of the shank are covered by a layer of a relatively resilient material. The layer is formed from a material which is suitable for compressing overlapping portions of the folded sheet of packaging material to form an intermeshing seal pattern. The outwardly facing portion of the layer of resilient material includes a longitudinally extending, outwardly facing resilient crimping surface with an undulating cross sectional shape. The lower crimpers are formed in a similar manner, except that an anvil is retained within the slot. During operation, the crimpers are rotated such that the folded sheet of packaging material is compressed between the downwardly facing undulating surface of the upper resilient layer and the upwardly facing undulating surface of the lower base. As a result, the overlapping layers which make up the folded sheet of packaging material are sealed together to form a trailing edge seal for a packaged article. The cutting blade and anvil cooperate to cut the sealed packaging material into individual units.
REFERENCES:
patent: 918060 (1909-04-01), Kabureck
patent: 1250959 (1917-12-01), Brown
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patent: 2442936 (1948-06-01), Rohdin
patent: 2556382 (1951-06-01), Williams et al.
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patent: 2607696 (1952-08-01), Kunz
patent: 2627893 (1953-02-01), Williams
patent: 2724424 (1955-11-01), Clayton et al.
patent: 3153607 (1964-10-01), Ambler
patent: 3243487 (1966-03-01),
Ball Michael W.
Lako Tool & Manufacturing, Inc.
MacMillian Sobanski & Todd, LLC
Musser Barbara J.
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