Abstract: This invention relates to the vacuum packaging of products and involves the use of a heat sealable thermoplastic bag in conjunction with a vacuum dome having a sealing edge disposed around its periphery and being connected to a source of vacuum, the thermoplastic bag being entirely closed except for an integral flat vent passage disposed at one peripheral location on the bag. One half of the vent passage is made up of material from one portion of the bag, and the other half of the vent passage is made up of a precisely equal amount of material from an opposite portion of the bag, such that the interior surfaces of said vent passage can tend to adhere together.

Abstract: Packaging of certain products like cheese is usually done in a vacuum without the presence of heat. Heretofore, a first vacuum was necessary to knit the curds together and to compact the cheese. A second vacuum was then employed to remove air which returned to the package. The present method eliminates the need for the second vacuum. A heat sealable package, containing cheese, and having a tortuous vent passage is subjected to a vacuum. As a full vacuum is achieved, air within the chamber and the package is exhausted. When the chamber is returned to atmospheric pressure, the tortuous seal collapses to form a temporary seal. At the same time, the plastic bag collapses around the cheese which causes the curds to knit together, and compact the cheese. While still in the sealed condition, a permanent heat seal is made across the tortuous vent passage.

Abstract: In plastic pouch forming, improved vacuum boxes that are movable toward and away from one another are provided. Each vacuum box comprises a series of superimposed, paired, mutually spaced vacuum ports in fluid communication with one another, the outer pair of ports being resilient and adapted to frictionally engage a wall portion of a flattened pouch and to flex open upon application of a vacuum to draw portions of the pouch wall into a cavity defined by an underlying port.

Abstract: In plastic pouch forming structure, a pair of vacuum ports such as, for example, cups are provided in each of a pair of opposed vacuum boxes that are horizontally movable toward and away from one another. Each vacuum cup comprises an insert having a first half-face portion that is substantially flush with the vacuum cup's sealing surface, and a second half face portion that is recessed as respects the first face portion. The dividing line between the face portions is essentially a vertically extending edge of the first face portion offset laterally as respects the diameter of the cup.