Reentrant Forming Apparatus

Abstract

A pair of dies engage a sheet of heat-softened foamed polystyrene plastic at a forming station and form it into a desired shape such as a carton. At the same station, and while the plastic is held between the dies, a portion of the plastic protruding from the dies is engaged on opposite sides by cooperating punches to impart a reentrant formation to the plastic that the dies alone could not impart. The reentrant formation facilitates releasably latching the top and bottom portions of the completed carton in a closed position.

Description

BACKGROUND OF THE INVENTION

This invention relates to the formation of materials into a desired shape and, more particularly, to novel and highly effective apparatus facilitating the forming of a material in a case where it is desired to impart a reentrant formation to the material which cannot be imparted, for example, by the simple act of bringing together a pair of dies on opposite sides of the material to be formed.

While the invention has many applications, it is here disclosed particularly as it relates to the formation of cartons from foamed polystyrene plastic. Very desirable cartons of this general description are disclosed and claimed in a copending application of Rohdin Ser. No. 814,254, filed Apr. 8, 1969, for "Carton Latch Construction," now U.S. Pat. No. 3,572,578 and very desirable methods and apparatus that can be used generally in the formation of cartons are disclosed and claimed in a copending application of Fred P. Brown, Jr., Ser. No. 815,292, filed Apr. 11, 1969, for "Method and Apparatus for Forming Containers." Both of the above-identified applications are assigned to the assignee of the present application.

SUMMARY OF THE INVENTION

An object of the present invention is to provide apparatus facilitating the production of a superior carton that is extremely inexpensive and that includes reentrant portions facilitating latching of the carton in a closed position.

The foregoing and other objects of the invention are attained by the provision, in a preferred embodiment thereof, of apparatus for use with a pair of dies and means mounting the dies for relative movement with respect to each other between an open position facilitating accommodation therebetween of a formable material and a closed position facilitating forming of the material at a forming station to a predetermined shape. In accordance with the invention, additional forming means is provided operatively associated with the dies, or at a separate forming station, and motive means is provided for bringing the additional forming means into cooperation with the material for further forming the material to a desired shape.

BRIEF DESCRIPTION OF THE DRAWING

An understanding of additional aspects of the invention may be gained from a consideration of the following detailed description of a representative embodiment thereof, in conjunction with the accompanying figures of the drawing, wherein:

FIGS. 1-3 are end elevational views, partly in section, of a representative embodiment of apparatus constructed in accordance with the invention in three successive stages of its operation;

FIG. 4 is a fragmentary side elevational view of the apparatus of FIGS. 1-3; and

FIG. 5 is an end elevational view, partly broken away, of a carton produced by the apparatus of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1-4 show apparatus 10 constructed in accordance with the invention. The apparatus 10 comprises a pair of dies 12 and 14 mounted for relative movement with respect to each other as shown by a double-headed arrow 16 between an open position facilitating accommodation therebetween of a formable material, as shown in FIG. 1, and a closed position, as shown in FIGS. 2 and 3, facilitating forming of the material 18 at a forming station 20 to a predetermined shape, including a protruding portion 22 shown in FIG. 2.

Additional forming means 24 is provided operatively associated with the dies 12 and 14. Motive means for the additional forming means 24 includes spur gears 26 and 27 and shafts 28 and 29, respectively, driven by the spur gears 26 and 27 for bringing the additional forming means 24 into cooperation with the material, as shown in FIG. 3, for further forming the material to a desired shape.

The additional forming means 24 comprises punch means and, more particularly, at least one punch 30 and another punch 32 mounted at the station 20. The punches 30 and 32 are keyed by keys 42 and 44, respectively, to the shafts 28 and 29 on which the punches 30 and 32 are respectively mounted. The shafts 28 and 29 can be parallel to each other so that the depth of the reentrant formations does not vary as a function of distance along the length of the completed carton or can be canted with respect to each other so that the reentrant formations are deeper at one end of the carton than at the other end. The latter embodiment provides a "zipper effect" facilitating opening and closing of the carton. The punches 30 and 32 are mounted in spaced-apart relation to each other, and they have respectively forming portions 34 and 36 and are paired for cooperation with each other. The motive means including the spur gear 26 and shaft 28 for operating the lower punch 30 and the spur gear 27 and shaft 29 for operating the punch 32 is adapted to move the punches 30 and 32 pivotally between a retracted position as shown in FIG. 2 facilitating accommodation of the formable material 18 between the forming portions 34 and 36 and an advanced position as shown in FIG. 3 in which the forming portions 34 and 36 engage the portion 22 of the material 18, the forming portions 34 and 36 being in vertically offset relation to each other. A counterpunch portion 38 on the punch 30 opposes the forming portion 36 on the punch 32, and, likewise, a counterpunch portion 40 on the punch 32 opposes the forming portion 34 of the punch 30.

The reentrant formation generally designated 46 (FIG. 3) thus formed includes an upper reentrant portion (as seen in FIG. 3) 48 and a lower reentrant portion 50. The portions 48 and 50 are both reentrant in the sense that they could not have been made by the dies 12 and 14, which move, as noted above, in the direction indicated by the arrow 16 in coming together on opposite sides of the material 18. As will be apparent, the forming portions of the respective punches 30, 32 may be arranged, if desired, to produce one or more holes in the material 18. In accordance with the present invention, it is thus possible to form the reentrant portions 48 and 50 concurrently with the principal formation effected by the dies 12 and 14, and, moreover, at the same station. Consequently, the formed cartons need not be passed to a separate station for the formation of reentrant portions. However, in certain cases the latter may be desirable, and it is within the scope of the invention to form the reentrant portions at a separate station by means of the novel forming apparatus 24.

Those skilled in the art will of course appreciate that reentrant formations have important advantages in the manufacture of cartons, such as for eggs and the like, out of foamed polystyrene and the like, for such construction is far better able to resist accidental opening of the cartons during stacking and so forth. In the example illustrated in FIG. 5, the formable material 18 is formed into a top 52 and a bottom portion 54, by the principal forming means 12, 14 and the portions 52 and 54 can be brought together and latched in a closed position by latch means including the reentrant portions 48 and 50 provided by the additional forming means 24. The principles of the invention are applicable, of course, regardless of the precise nature of the formation imparted by the main forming means and the latter may be used to form carton trays or lids, only, rather than complete cartons.

The formable material 18 can be expandable polystyrene foam, biaxially oriented polystyrene sheet material, high-impact polystyrene, a multipolymer, polypropylene, polyethylene, ABS, a laminated construction or other thermoplastic material. In accordance with the invention, egg cartons, cottage cheese containers, margarine tubs, etc., may be manufactured more efficiently, quickly, and economically than has heretofore been possible.

It is within the scope of the invention to employ gripping members for gripping and advancing the material through a machine that performs other steps in addition to the forming steps. For example, preheating may be effected in order to facilitate thermoforming, and also printing and the usual trimming and the blanking may be effected in order to produce a neat and commercially desirable finished product.

Many modifications of the representative embodiment described herein will readily occur to those skilled in the art. For example, the means effecting the reentrant formations need not move pivotally; such means can be made to execute other kinds of movement, including rectilinear or curvilinear reciprocating movement. Moreover, the forming portions of the punches 30, 32 may be located at various positions along their lengths, dependent upon where the desired formation is to be produced in the carton. This may be adjacent the edge or substantially inwardly thereof. The invention is to be construed as including all of the embodiments thereof within the scope of the appended claims.

Claims

We claim:

1. In forming apparatus having a pair of dies adapted for relative movement towards each other to impart a predetermined shape to a blank of formable material inserted therebetween and reentrant forming means for imparting a reentrant formation to said blank having said predetermined shape imparted by said dies, the improvement wherein said reentrant forming means comprises a pair of cooperating punches and means mounting said punches for relative movement with respect to each other, the relative movement of said punches with respect to each other being different from the relative movement of said dies with respect to each other and each punch having a protruding forming portion and a recessed counterpunch, the forming portion of each punch cooperating with the counterpunch of the other punch.

2. In forming apparatus having a pair of dies adapted for relative movement towards each other to impart a predetermined shape to a blank of formable material inserted therebetween and reentrant forming means, the improvement wherein said reentrant forming means comprises a pair of cooperating punches and drive means for moving said punches towards each other, each punch having a protruding forming portion and a recessed counterpunch, the forming portion of each punch cooperating with the counterpunch of the other punch, and said punches being respectively movable towards each other by said drive means in a direction different from the direction of relative movement of said dies towards each other to impart a double reentrant formation to material inserted therebetween.

3. Apparatus according to claim 2, wherein said drive means includes a pair of rotatable shafts and wherein each of said pair of punches is mounted for rotation on a different one of said shafts, whereby said punches are pivoted upon rotation of said shafts to impart said double reentrant formation to said material.

4. Apparatus according to claim 3 wherein said shafts are parallel to each other.