Package making – Progressively seamed cover web or web folds – With closing of web between package units
Reexamination Certificate
1998-10-19
2001-02-06
Tolan, Ed (Department: 3725)
Package making
Progressively seamed cover web or web folds
With closing of web between package units
C053S412000, C053S451000, C053S133200
Reexamination Certificate
active
06182426
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention is concerned with the manufacture of stand-up pouches, and more particularly with the manufacture of liquid-filled stand-up (self-supporting) pouches of thermoplastic film, by a vertical form, film, seal (F/F/S) machine.
At present, horizontal F/F/S machines are used to package dry flowable products. Liquid filling of stand-up pouches, when performed on such machines, is generally limited to small volume pouch sizes. This is a reflection of the manner in which the machines operate.
In a horizontal machine, before a pouch is filled it is completely formed, with the exception of an open top. To fill the pouch, it is handed off to a set of grippers on a rotating, intermittent motion filling/sealing section. The grippers are actuated to open the top of the pouch, and a predetermined quantity of a free flowing product is funneled into the pouch. The top is then heat sealed.
Handling large volumes of liquid in pouches on a rotating, intermittent motion filling/sealing section is difficult, because of the weight of the liquid and its fluidic activity.
Horizontal machines have limitations in addition to pouch size. The step-up or pull length of the pouch is not easy to modify, since the grippers that open the top of the pouch must be set to the exact pouch width. Since a number of pouches may be open and exposed to the surrounding environment during filling, it may be necessary to provide an enclosure and filtration or over-pressurization apparatus to avoid product contamination. Furthermore, the placement of fitments and the types of pouch films that can be used tend to be limited.
Vertical machines have been used to produce liquid-filled pouches. See, e.g., commonly owned U.S. Pat. No. 4,947,621, incorporated herein by reference. However, such machines are not designed to produce stand-up pouches.
SUMMARY OF THE INVENTION
The present invention provides improved apparatus and methods for forming, filling and sealing stand-up pouches, more particularly for producing such pouches on vertical machinery in a manner that avoids the problems associated with horizontal F/F/S machines.
In the invention, pouches are part of a continuous film web until they are complete. Larger fill volumes can be accommodated, because the pouches are supported by the continuous web during filling and sealing. Cleanliness is assured, because filling takes place within the confines of the continuous web. Fitments can be applied to the pouches without impeding the filling operation. Size changes are easier to make, providing flexibility in the manufacturing operation. A wider variety of film structures can be utilized.
A preferred embodiment of a vertical F/F/S machine in accordance with the invention will now be described briefly. However, it will become apparent that various features of the invention have broader utility.
In the preferred embodiment, a flat, wide, vertical fill tube is surrounded by an elongated envelope of thermoplastic film. Initially, the envelope is closed along one longitudinal edge and is open along the opposite longitudinal edge. Drive members of a main drive assembly press the sides of the envelope against the respective sides of the fill tube and drive the envelope step-wise, each step corresponding to one pouch pitch.
A cup-former, including cup shaping, sealing and chilling apparatus, transforms a portion of the envelope along the closed edge into a series of cups, each of which will constitute a stand-up base at the bottom of a corresponding pouch formed by the machine. More particularly, each cup is initially formed as a gusset, the cross-section of which is W-shaped, and the shape is maintained by heat sealing and chilling operations.
The open edge of the envelope opposite to each cup receives a fitment that is spot sealed to the envelope. A further heat sealing operation closes the open edge of the envelope around the fitment to form a top seal of the corresponding pouch and to attach the fitment permanently.
End sealer/cut-off assemblies provide a transverse end seal at the bottom of the envelope, and release each completed pouch from the envelope. The end seal simultaneously seals abutting side edges of a leading pouch and a next pouch being formed. The leading pouch has just been filled, and the next pouch is about to be filled. The sealing of a side edge of the next pouch provides a receptacle into which a predetermined quantity of liquid is dispensed by opening a valve at the bottom of the fill tube. Just before each end seal is formed, deflater plates engage the envelope from opposite sides, to flatten the envelope and control the residual air volume in the filled pouch. A cut-off knife bisects each end seal to separate the filled leading pouch from the envelope.
In the preferred embodiment, the envelope is formed by a folder (forming plow) at the top of the machine. The folder folds in half a web of thermoplastic film supplied from a film roll. The film roll is adjustably braked in accordance with the amount of film on the roll to provide constant drag as film is pulled from the film roll by an auxiliary film drive assembly. A film path from the film roll to the folder is defined by a series of idler rollers, and by rollers of a dancing bar that moves in response to changes in film tension. The auxiliary film drive assembly has rollers that pinch the web therebetween at a position along the film path between the film roll and the dancing bar. The speed of the auxiliary film drive is responsive to movement of the dancing bar to maintain constant film tension.
At a position along the film path between the dancing bar and the folder, the film is wrapped about a brake roller. When power is applied to the machine, but the film is not moving, the brake roller is locked to isolate the portion of the film path leading from the brake roller to the folder.
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Liqui-Box Corporation
Tolan Ed
Vorys Sater Seymour and Pease LLP
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