Packaging apparatus for making hermetically sealed vacuum packages from two continuous webs of plastic packaging material supplied as roll stock. The lower web is formed into product receptacles, and the upper web is applied over the receptacles to serve as the top. The apparatus includes a single-station evacuate-and-seal head where the two webs are initially sealed together around the flanges of the receptacle. The resulting package is then evacuated through a slit in the lower web, and the evacuation slit is sealed off to complete the package. During evacuation, the upper web is shifted up to engage a heated plate to raise the web temperature to a level permitting forming of the plastic material. After final sealing, the spaces above and below the packages are sequentially vented to atmosphere so as to control the formation of the upper web to produce a crowned effect, wherein a portion of the product extends upwardly a small distance above the flanges of the package.
A support tray 6a with a product 11a thereon is covered loosely by a cover sheet 8 in a first chamber portion 12 to be drawn upwardly into contact with the heated walls of a shallow first mould cavity. The combination of the product 11a, support tray 6a and cover sheet 8 is then advanced to a second chamber portion 13 defined by a deeper second mould cavity into which the cover sheet can be drawn while vacuum is applied to the interior of the ensuing pack through slits in the tray 6a, by means of suction ports 20.
A method of preparing a package having a product enclosed between a support member and a multiple-film lid, comprising the steps of providing a support member supporting a product; providing a multiple-film lid over the product and the support member, the multiple-film lid having a first film for enclosing the product on the support member when sealed thereto and a second film over the first film, the first film and the second film defining a first space therebetween and the first film and the support member defining a second space therebetween; evacuating the first and second spaces; and sealing the multiple-film lid to the support member so as to form a sealed package.
A method for packaging a product arranged in a tray is provided. An upper film located in a distance above the product is clamped along an edge surrounding the tray and is deformed in a direction extending away from the product. Subsequently, evacuating of the space surrounding the product is performed, then a raising of the tray towards the upper film and finally a sealing of the film and of the edge of the tray. In this way, the seam of the upper film and the edge of the tray is attained to be free from creases such that a long-living and good looking package is produced. Additionally, a packaging machine for performing the method is provided.
A packaging process is disclosed which includes the steps of providing a tray, providing an upper film which includes a sealant layer which is sealable to the tray, orienting the film to an orientation ratio of from about 6.0:1 about 16.0:1 positioning, a high profile product on the tray, extending the upper film above the tray and product, drawing the upper film into a concavity by differential pressure, maintaining the concave shape of the upper film while heating the film, removing gases from the space between the upper film and the tray and product, introducing a desirable gas into the space, releasing the upper film such that it shrinks toward the product and the tray while the desirable gas is retained within the space and prevents close contact of the film with the lowermost portions of the product, and sealing the upper film to the flange of the tray, wherein at least the step of heating the film shrinks the film, thereby tensioning it onto and across the underlying product. The resultant package of the high profile product provides an in-store overwrap appearance.
