Abstract: 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.

Abstract: 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.