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.
This is a continuation, of application Ser. No. 856,218, filed on Dec. 1, 1977, which in turn is a divisional of Ser. No. 748,650 filed Dec. 8, 1976, now U.S. Pat. No. 4,085,565.
An apparatus that receives packaging containers and a mixture of powdered chemicals and compresses the powder into the containers at a pressure sufficient to form a solid of the powder yet not so high as to rupture the container. The apparatus is computer controlled and fully automated. The apparatus mixes a batch of chemicals in powder form, apportions a quantity of the mixture into the container and compresses it into a solid. Alternatively, the apparatus comprises a mold instead of the container for receiving the mixture portion, presses the portion into the mold and then the mold is rotated in a vertical plane to discharge the molded portion.
A plastic film bottom tray is held in shape by a rigid bottom rim. A plastic film top is held in shape by a rigid top rim above the tray. Substance to be lyophilized is frozen in the tray. The assembly is lyophilized in a vacuum chamber. Apertures formed between the top and the tray provide fluid pathways for efficient sublimation. After dehydration, the top rim is pushed down into the bottom rim, obliterating the apertures and pressure sealing the two films together in-vacuo. After removal from the vacuum chamber, the two films are heat sealed together, forming a lyophilized product vacuum sealed within a plastic film bag. Rims and film beyond the heat seal are trimmed away.
A vacuumizing and sealing operation on a package comprises initially reducing the external pressure on the package, before sealing of the package, to a value at which the flexible film covering of the package is capable of ballooning, and ensuring heating of the flexible film of the package, preferably while an intermediate pressure is maintained (at which intermediate pressure ballooning could just be sustained without excessive evacuation to reduce the thermal capacity of the circulating air). Finally the pressure inside and outside is reduced still further before re-pressurizing.
A vacuumizing and sealing operation on a package comprises initially reducing the external pressure on the package, before sealing of the package, to a value at which the flexible film covering of the package is capable of ballooning, and ensuring heating of the flexible film of the package, preferably while an intermediate pressure is maintained (at which intermediate pressure ballooning could just be sustained without excessive evacuation to reduce the thermal capacity of the circulating air). Finally the pressure inside and outside is reduced still further before re-pressurizing.
By providing raised peripheral edges, preferably walls, for the supporting member of a vacuum skin package, a superior vacuum package is achieved when a product is vacuum packaged on such a supporting number. Wrinkles and weak spots are avoided. Preferably, the raised edges are formed in-line as the package is made.
