US3488413A

US3488413A - Method for forming packages

Info

Publication number: US3488413A
Application number: US576658A
Authority: US
Inventors: Ridley Watts Jr
Original assignee: American Packaging Corp
Current assignee: Nordson Corp
Priority date: 1966-09-01
Filing date: 1966-09-01
Publication date: 1970-01-06
Anticipated expiration: 1987-01-06

Description

1W 5%. WATTS, m METHOD FOR FORMING PACKAGES Filed Sept. 1, .1966

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ATTO NEYS United States Patent 3,488,413 METHOD FOR FORMING PACKAGES Ridley Watts, Jr., Cleveland, Ohio, assignor to The American Packaging Cor oration Filed Sept. 1, 1966, Ser. No. 576,658 Int. Cl. B29c 23/00, 17/00; 132% 7/02 US. Cl. 264-89 3 Claims ABSTRACT OF THE DISCLOSURE This invention relates to the forming of packages, especially card-type display packages having a preformed pocked or window area for containing and displaying the article packaged.

In present-day merchandizing, many retail products are packaged in separate units in order to shOW the products attractively against a display background which can contain artwork, illustrations of use, trademark, and the like. These individual packages facilitate self-service sales, serve as protection in shipment, and deter pilferage.

One type of package which is ideally Suited for retail display and other purposes, and methods of making packages of this type are described in greater detail in U.S. Patents 3,053,023 and 3,217,462 issued respectively Sept. 11, 1962, and Nov. 16, 1965 and copending application Ser. No. 213,804 entitled package, now Patent No. 3,298,- 515, issued Jan. 17, 1967, all issued to Ridley Watts, Jr. and assigned to American Packing Corporation. The packages described in these patents and other known packages fall into the general class in which the product is encased within the clear plastic enclosure and the plastic and enclosed products are secured to a support card.

With the package described in the Watts patents, a plastic film is secured to a card to cover and close one or more apertures in the card. The film is preformed to provide flexible, shape-retaining pockets contoured to a predetermined shape. The pockets are projectible through selected apertures and are collapsible. Once the pockets have been formed containers can be stacked tightly together for shipping and/or storage until they are subsequently loaded. On loading each product is inserted into a flexible pocket, and the container is then closed so that each product redistends its flexible pocket. Thereafter the card is sealed in a closed condition as by heat-sealing two halves of the card together.

In forming the plastic pocket or pockets of card-type display packages, it is customary to heat the plastic film forming the pocket to a temperature at which the film is softened. The plastic film is then vacuum formed or pressed to a desired shape, allowed to cool to a temperature at which it is dimensionally stable, and then removed from the forming die. One machine for forming pockets in the plastic film of an apertured card is disclosed in the copending patent application of Ridley Watts, Jr. and John F. Berry, Ser. No. 520,485, filed Ian. 13, 1966, entitled Package Forming Machine and Method and assigned to American Packaging Corporation.

There are several disadvantages and limitations to the known machines and techniques for heating and forming the plastic pockets of display packages. Difficulties are encountered in heating the film, obtaining uniform thickness of the pocket during forming, and cooling the film rapidly. These difficulties include (1) radiant heat is generally not acceptable because of the transparency of the film and (2) it is difiicult to control the forming operation in a manner which results in proper film thickness in all areas of the pocket especially at etficient production speeds.

Thus, in machines that function to form the plastic film, the difficulties in heating, forming and rapidly cooling the film cause problems in forming a pocket of uniform thickness. A multiplicity of forming molds are usually required and a long heating zone is necessary to facilitate the substantial time necessary to heat, form and cool each individual package, in continuous forming machines.

As suggested above, when the heated film is formed, either by vacuum forming in a concave mold or by a press, the film quite often stretchesunevenly. This is because the portion of the film that first contacts the mold or forming member becomes cool and stabilized while remaining portions are then stretched to a greater degree until the final shape is reached. Differential stretching results in thickness variations in the film. These variations can be diminished by keeping the forming dies or molds relatively warm. However, an abnormally long cooling time is then required before the film reaches a temperature at which it is dimensionally stable and can be removed from the mold.

These and other disadvantages of the present forming techniques have been overcome by the present invention. In accordance with this invention, the thermoplastic film across the aperture of a card-type package is heated and formed by the flow and pressure of a heated gas impinging upon one surface of the film.

In the preferred embodiment, the card is positioned with the plastic film to be formed between a mold cavity and a complementary ram. The ram is formed with a porous forming surface through which a diffused flow of gas at an elevated temperature is emitted. The gas impinges against and flows across the plastic film, transferring heat by convection at an extremely high rate. The ram and mold are moved together to form the pocket. The ram deforms the plastic film, which has been softened by the hot gas, and forces it into the cavity of the mold. The difiused flow of gas provides a lubricating film over the surface of the ram, so that the ram does not dir ctly contact the softened film. The small gap or spacing between the forming surface of the ram and the film assures a high rate of heat transfer by the continuous flow of hot gas. Moreover, since the plastic film does not contact the ram and is substantially formed before it contacts the mold, the distribution of the stretching is closely controlled.

Accurate shape and rapid cooling of the pocket after forming are assured by the mold construction. Passageways for evacuating the cavity assist the ram in forming the pocket to the desired shape. The softened film is drawn into intimate contact with the shape defining cavity and heat of the film is rapidly conducted away and dissipated by the mold. For the latter purpose the receiving mold is maintained at a low temperature that substantially immediately chills the film. The card and formed pocket can therefore be removed from the mold immediately after forming. Thus, a high speed forming operation is possible.

It is therefore an object of this invention to provide improved methods for forming plastic pockets or pouches in display type packages. Other objects, features and advantages of this invention will become apparent as the invention becomes better understood by reference to the following detailed description, when considered in connection with the accompanying drawings, in which:

FIGURE 1 is a diagrammatic transverse sectional view of a ram and mold constructed in accordance with the present invention, and showing the ram and mold in spaced relation;

FIGURE 2 is a diagrammatic transverse sectional view of the apparatus of FIGURE 1, showing the ram and mold in mating relationship, forming a pocket from a film of plastic;

FIGURE 3 is a fragmentary enlarged view of a portion of the ram shown in FIGURE 1;

' FIGURE 4 is a perspective view of a finished unloaded container; and,

FIGURE 5 is a perspective view of a loaded package. Referring now to the drawings, FIGURE 1 shows a general arrangement with a container supported upon a mold 12 beneath a forming ram 14. The container 10 is illustrative of one of many card-type containers that can be formed in the manner and with the apparatus disclosed herein. The container 10 includes a flat stiffening card structure 16, such as cardboard, having a central aperture 18. A thermoplastic film is adhered to the upper surface of the card 16 and extends across the aperture 18. For clarity, the thicknesses of both the card 16 and film 20 are exaggerated in the drawings. One suitable thermoplastic film is polyethylene. This film can be heated and formed to a desired contour, and retains the formed contour after it has cooled. It is also heatsealable, which facilitates sealing the package after it is loaded with a product.

Where the container 10 is in the form of a single panel having a single aperture, as shown in FIGURES 1 and 2, the package is completed by a second flat cover card. The card 16 can alternatively be divided into two panels 21, 22. FIGURE 4, by a fold line. An aperture and pocket can be provided in each panel if desired. Such a card is indicated at 10' in FIGURES 4 and 5. The card 16 is folded along the fold line to complete the package 10, by bringing the two apertures and pockets into alignment. Such a package is disclosed in the aforementioned patents issued to Ridley Watts, Jr. Containers of various other constructions such as so called blister packages using other thermoplastic sheet or films can also be formed in the manner and with the apparatus disclosed herein.

A container 10 is shown in FIGURE 2 with a pocket 20a formed in the thermoplastic film 20, within the aperture 18. This pocket is formed by heating and stretching the film in the pocket area, as will be described subsequently.

The mold or die 12 includes a flat top surface 23 for supporting the container 10. A cavity 24 is formed in the top surface 23 with a peripheral contour corresponding to the aperture 18. Stops (not shown) locate the container 10 in proper position upon the top surface 23, with the aperture 20 of the card 10 directly over the cavity 24. A plurality of passageways 26 communicate between the bottom of the cavity 24 and a manifold 28 within the mold 12. A conduit 30 extends from the manifold 28 through the mold 12 and is connected to a source of vacuum 32, as indicated diagrammatically in FIGURES 1 and 2.

A plurality of passageways 34 are formed in the body of the mold 12 for circulating cooling fluid. These passageways are connected to inlet tubes 36 and outlet tubes 37 which circulate cooling liquid through the passageways 34. The mold 12 is preferably constructed of metal and is highly thermoconductive.

The forming ram 14 includes a plenum chamber 40 with a forming surface 44 that functions as a die to form a pocket in the plastic film 20. The forming surface fits within the cavity 24 of the mold 12. A hollow actuating rod 42 supports the plenum chamber and serves to supply hot gas under pressure to the plenum chamber 40 from a source P, diagrammatically indicated. The forming sur- 4 face 44 of the plenum chamber is porous or foraminous, and may be suitably formed of sintered powders of metals or refractory materials. Other apertured surfaces may also be used. As best illustrated in FIGURE 2, the forming surface 44 is smaller than, but complementary to, the cavity 24.

As diagrammatically indicated by the two positions of the ram 14 and mold 12 in FIGURES 1 and 2, they are supported forrelative movement toward and away from each other. As indicated by the arrow A, the actuating rod 42 moves the ram 14 vertically. Another suitable arrangement for moving opposed dies toward and away from each other, particularly in intermittent synchronization with a conveyor, is disclosed in the copending application of John F. Berry, Ser. No. 445,386 filed Apr. 5, 1965 and entitled Packaging Machine and Method.

As diagrammatically illustrated in FIGURE 3, the preferred embodiment of the ram 14 includes a thin layer of a low friction coating 48. One particularly suitable coating is a tetrafiuoroethylene resin sold on the market under the trade name of Teflon. Such a coating may be applied to the forming surface 44 by spraying the sur face with an aqueous dispersion of finally divided tetrafluoroethylene. The coating is applied sparingly so as not to seal the porous openings through the surface. This coating 48 overcomes any tendency of the thermoplastic film 20 from adhering from the forming surface 44 in the event it comes into direct contact.

In the operation of the forming apparatus described, as used to form a pocket 20a in a display type package, such as the container 10, the fiat card 16 is first placed between the ram 14 and the mold 12. The card 16 is supported directly on the surface 23 of the mold 12, as shown in FIGURES 1 and 2 of the drawing, or can be supported independently, as by a conveyor or track. It will be observed in FIGURE 1, that with the card in place, the forming surface 44 of the ram 14 is directly opposite and in close proximity to the thermoplastic film 20 that extends across the aperture 18. A continuous flow of hot gas, indicated diagrammatically by the small arrows associated with the ram 14 in FIGURE 1, is introduced through the hollow rod 42 and into the plenum chamber 40. The gas is heated to a temperature sufiicient to rapidly soften the film 20 whenimpinged against the film. Heated air is suitable. The hot gas under pressure within the plenum chamber 40 then flows through the porous forming surface 44 and is emitted in a diffused flow that impinges against the adjacent thermoplastic film 20. The passageways or pores through the forming surface 44 are sufiiciently small that they provide a substantial pressure drop, which makes the flow through the forming surface 44 substantially uniform throughout and independent of the proximity of the forming surface to the film20. The pores are sufiiciently close that an essentially complete lubricating film of hot gas is provided over the entire forming surface.

The diffused fiow of hot gas emitted from the forming surface 44 begins heating the thermoplastic film 20 as soon as the film is placed between the ram and mold. When the ram and mold are moved relatively together, the rate at which the film 20 is heated increases rapidly due to the direct impingement, and higher velocity of gas flow across the surface of the film 20 due to the close spacing. The thermoplastic film 20 is almost immediately brought to a temperature at which it is soft enough to be formed to thedesired finished shape. This shape is achieved by stretching the film 20 in the area of the aperture 18 by a pressure differential on opposite sides of the film 20.

The flow of hot gas through the forming surface 44 provides a lubricating film of gas under positive pressure that spaces the plastic film 20 from the surface 44 of the ram 14 and forces the softened film 20 into the cavity 24 in response to relative movement .between the ram and the mold to theposition shown in FIGURE 2. At the same time, the cavity 24 is evacuated to assist in forming the film 20 and to assure initimate contact of the pocket portion 20a with the cavity 24. The heated portion of the film 20 is readily stretched as the ram 14 is positioned Within the cavity 24. The stretching is substantially uniform throughout the entire area of the pocket because the entire area has been heated to a temperature at which the film flows and because there is little or no opportunity for the film 20 to contact or adhere to the forming surface 44 of the arm 14. Moreover, the film is maintained hot and soft throughout the forming operation by the heated ram. In the event there is actual contact between the ram and the film, the Teflon coating 48 minimizes the adverse effect.

The mold 12 is maintained at a low temperature, sufficient to rapidly lower the heated portion of the film 20 to a temperature at which it is dimensionally stable. The mold 12 is maintained at such a temperature by cooling fluid circulated through the inlet and outlet pipes 36, 37 and through the passageways 34 within the mold. Because the forming operation is initiated by the ram 14, the pocket 20a is stretched toward the desired configuration before any part of the pocket comes in contact with the chilled mold 12. Even if a portion of the pocket contacts the cavity prematurely, as at the upper periphery, the proximity of the heated ram 14 and continuous flow of hot gas prevents the film from becoming chilled before the completion of the forming operation. Upon removal of the ram 14 from the cavity 24, the pocket 20a is immediately set, i.e., cooled to a temperature where it is dimensionally stable. The container can be removed at once from the mold 12 and a new card inserted.

Another technique for chilling or freezing the film is to stop the flow of hot gas through the ram 44 and substitute for it a relatively cool flow of gas for chilling the film. With this technique the mold cavity 24 may be maintained at a more elevated temperature while essentially the same forming speeds are achieved. Further, it is possible to achieve different distributions of the film stretch and stresses and therefore to control the thickness of the film in the pocket differently than in the preferred embodiment discussed above where the mold is chilled.

After the container has been finished by either process it is stripped from the mold and the formed pocket is partially flattened. The containers may then be shipped to the product as is described more fully in the above-referenced Watts patents and subsequently a product inserted in the container. In FIGURE 4 the container is shown in a partially folded condition with the product not yet inserted. It will be seen there that the formed pocket is still in a partially collapsed condition. On insertion of the product and sealing of the card sections 21, 22 together, the pockets are redistended and the completed package shown in FIGURE 5 is produced.

What is claimed is:

1. In a method of forming a pocket in a thermoplastic film for a card-type display package or the like, the stops comprising:

(a) supporting the film initially in a generally planar condition on a mold over a cavity of the shape to which the pocket is to be formed,

(b) positioning a ram, which is shaped to fit into the cavity and which has a porous convex operating surface, adjacent said film and opposite the cavity,

(c) heating the film essentially from one side only to a temperature at which it is soft enough to be formed, by impinging a diffused flow of gas from the ram upon the surface of the film that faces away from the mold, which gas is at a temperature sufiicient to soften the thermoplastic film,

(d) establishing relative movement between the ram and mold to position the ram at least partially within the cavity to initially deform the film from its planar condition into the mold cavity, while (e) maintaining a suflicient flow of gas from the ram to continually maintain a gaseous cushion between the ram and the film to prevent contact therebetween,

(f) withdrawing gas from the mold cavity concurrently with relative movement of the ram into the cavity, and

(g) thereafter relatively moving the ram and mold to remove the ram from the mold cavity.

2. The method of claim 1 including the step of cooling the mold to a temperature at which the film will set to a formed contour while the mold and ram are brought together.

3. In a method of manufacturing a card-type package in which a thermoplastic fihn is adhered to a panel of a card and across an aperture thereof, the steps comprising:

(a) supporting a panel portion of said card-type package with the film in a generally planar condition on a mold, with the aperture of the card over a cavity in the mold, Which cavity is of the shape to which the pocket is to be formed,

(b) positioning a ram, which is shaped to fit into the cavity and which has a porous convex operating surface, adjacent the film across the aperture of the card and opposite the cavity,

(c) heating the film that extends across the aperature of the card essentially from one side only to a temperature at which it is soft enough to be formed, by impinging a diffused flow of gas from the ram upon the surface of the film that faces away from the mold, which gas is at a temperature sufficient to soften the thermoplastic film across the aperture of the card,

(d) establishing relative movement between the ram and mold to position the ram at least partially within the cavity to initially deform the film across the aperture of the card from its planar condition into the mold cavity, while (e) maintaining a sufiicient flow of gas from the ram to continually maintain a gaseous cushion between the ram and the film to prevent contact therebetween,

(f) withdrawing gas from the mold cavity concurrently with relative movement of the ram into the cavity, (g) cooling the mold to a temperature at which the film will set to a formed contour while the mold and ram are brought together, and

(h) thereafter relatively moving the ram and mold to remove the ram from the mold cavity.

References Cited UNITED STATES PATENTS 3,007,206 11/ 1961 Griswold.

3,053,023 9/1962 Watts.

3,217,462 11/1965 Watts 53-37 2,926,385 3/ 1960 Willson -1 26489 2,973,558 3/1961 Stratton 26489 2,990,581 7/1961 Rowe 26489 3,159,693 12/1964 Plymale 26493 3,291,874 12/1966 Negoro 26489 3,316,594 5/ 1967 Hoffer 26489 ROBERT F. WHITE, Primary Examiner J. H. SILBAUGH, Assistant Examiner U.S. Cl. X.R 18--19; 26492, 93