SIDEWALL BLANK FOR SUBSTANTIALLY ELIMINATING TWIST IN DEEP BOTTOM CONTAINERS

Abstract

A cup forming sidewall blank includes a piece of flexible sheet material having an upper edge, a lower edge, and a pair of opposite side edges with an area at or adjacent the lower edge of the sidewall blank being provided with relief formations which extend generally upwardly and perpendicularly relative to the lower edge. The relief formations preferably take the form of score lines, slits, notches or other suitable constructions which are generally spaced from one another and are of equal length relative to the sidewall blank lower edge.

Description

FIELD OF THE INVENTION

The present disclosure relates to the manufacture of two piece, seamed paper cups coated with thermoplastic, and more particularly, pertains to the manufacture of cups having a deep bottom formation.

BACKGROUND OF THE INVENTION

The assignee of the instant application, Paper Machinery Corporation of Milwaukee, Wis., USA, is the manufacturer of paper cup making machines used to make to a variety of cups and containers. A typical cup machine for making paper cups, for instance, includes a turret having a plurality of mandrels about which the containers are formed. The turret sequentially rotates the mandrels into cooperation with a variety of workstations where numerous cup forming procedures occur.

In an exemplary procedure, a circular bottom blank is cutout at one workstation and attached to the end of a mandrel by a vacuum applied through the mandrel. During this procedure, the outside edge or lip of the bottom blank is folded downwardly. At a subsequent workstation, a sidewall blank is wrapped around the mandrel. The sidewall blank is heated and sealed along an overlapped side seam which runs generally longitudinally along the side of the cup. Typically, a paperboard is coated with a thermoplastic material such as polyethylene, polypropylene or a solid plastic sheet can be used, so the bottom and sidewall blanks may be heated and sealed together. In some applications, the sidewall blank includes a flap extending beyond the lip of the bottom blank, and this flap is bent over the lip. At a bottom finishing station, the flap is pressed against the lip from an inside recessed area of the bottom of the cup. By heating the thermoplastic and firmly pressing the sidewall, sidewall flap and bottom flap lid together, a bottom seal is formed and the cup is provided with a sturdy bottom region having a recessed area. There may be also workstations where various other additional cup forming procedures are carried out. For example, one station may be used to provide a curl at the top or rim of the cup to provide a more functional drinking container and a better appearance.

Certain cups are manufactured according to the above exemplary procedure with a deep bottom formation in which the recessed area is defined by a bottom which is raised and spaced typically about ½″-⅝″ from the lowermost peripheral edge that supports the cup. Traditionally, the external peripheral surface of the deep bottom formation on the cup results in an undesirable twist or wrinkle effect (as depicted at T in the cup C of FIG. 1) which detracts from the appearance of the cup and can result in potential leakage problems.

Accordingly, it is desirable to substantially eliminate the twist or wrinkle effect that normally occurs in the formation of deep bottom cups and containers to provide a smooth, uniform aesthetic appearance on the external surface of the lowermost or bottom region and prevent leakage therefrom.

SUMMARY OF THE INVENTION

The present disclosure relates to a two piece cup formed by a sidewall blank having an upper edge, a lower edge, a pair of opposite side edges, a front surface and a back surface with the opposite side edges overlapped and sealed along an overlapped side seam to a bottom blank along a lower edge of the sidewall blank. The invention is improved wherein an area at or adjacent the lower edge of the sidewall blank is provided with relief formations which extend generally upwardly and perpendicularly relative to the lower edge. The relief formations preferably take the form of score lines, slits, notches or other suitable constructions which are generally equally spaced from one another and are of equal length relative to the sidewall blank lower edge.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the best mode presently contemplated of carrying out the invention.

In the drawings:

FIG. 1 is a front view of a prior art formed two piece cup exhibiting a twist on the external surface of the lowermost region of the cup;

FIG. 2 is a perspective view of a formed two piece cup constructed using the sidewall blank of the present invention;

FIG. 3 is a schematic plan view of an exemplary cup making machine for making a cup with the sidewall blank of the present invention;

FIG. 4 is a perspective representation of a bottom blank and a sidewall blank used in forming a cup shown in FIG. 2;

FIG. 5 is a sectional view showing the area at which the sidewall blank is joined to the bottom blanks;

FIG. 6 is a plan view of the sidewall blank of FIG. 4 illustrating one embodiment of the present invention;

FIG. 7 is a plan view of a second embodiment of the sidewall blank used to form the cup of FIG. 2; and

FIG. 8 is a plan view of a third embodiment of the sidewall blank used to form the cup of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

Referring generally to FIG. 3, an exemplary cup making machine 20 is illustrated. This particular design includes a mandrel turret 22 which cooperates with a transfer turret 24 and a rimming turret 26. Mandrel turret 22 includes a plurality of mandrels 28 that are rotated in a stepwise or indexing manner between a surrounding workstations. For example, a bottom blank may be applied to a given mandrel 28 at a bottom blank maker workstation 30 and then rotated to a bottom reformer station 32. From this point, the mandrel 28 is rotated into cooperation with the transfer turret 24 which receives sidewall blanks from a hopper 34 and rotates the sidewall blank into cooperation with an adjacent mandrel 28. The sidewall blank is then folded about the mandrel over the bottom blank, heated and sealed along a side seam where the opposite side edges of the sidewall blank overlap.

Next, the bottom blank and the sidewall blank are rotated to a bottom heat station 36. After heating, mandrel turret 22 indexes the subject mandrel 28 into registration with a roller incurl workstation 38 where a portion of the sidewall blank, i.e. a sidewall blank flap, is bent over an outer lip of the bottom blank to form a recessed bottom in the cup. The cup is then moved to a bottom finishing station 40 where the sidewall blank flap and the bottom blank lip are pressed against the lower region of the sidewall blank to form a bottom seal.

Once the bottom is formed and sealed, the seal is transferred to rimming turret 26, rotated to a lube station 42 and then rotated to a rimming precurl station 44 where the upper lip of the sidewall is curled outwardly. From that station, the cup is indexed to a rimming finish curl station 46 which finishes the curled portion along the top of the cup to make an attractive edge. At this point, the cup may be moved to an optional lid groover station 48 and then to a cup blow off station 54 for removal of the finished cup.

Referring to FIGS. 2, 4 and 5, an exemplary cup 52 includes an upper region 54 having a curled rim 56 and a bottom region 58. Cup 52 is made from a flexible sheet member or sidewall blank 60 of generally trapezoidal shape which is wrapped around a circular bottom blank 62 disposed generally transverse thereto. Sidewall blank 60 has front and back surfaces as well as opposite side edges 60a, 60b, an upper curved edge 60c and a lower curved edge 60d. Bottom blank 62 is typically bent or folded over in proximity to its outer edge to form a lip 64. The sidewall blank 60 is located with respect to bottom blank 62 so that a flap portion 66 having a bottom edge 65 extends beyond lip 64. Flap portion 66 is bent or folded around lip 65 so lip 64 may be squeezed between flap portions 66 and the lower region of sidewall blank 60.

A typical cup 52 is made from paperboard blanks having a thermoplastic coating such as polyethylene. The thermoplastic material permits heating and sealing of adjacent components. For example, when sidewall blank 60 is wrapped around bottom blank 62, adjacent overlapped edges 60a, 60b are heated and pressed together along an overlapped side seam 68. Similarly, lip 64, flap portion 66 and lower region 67 of sidewall blank 60 may be heated and pressed together at a bottom finish station 40 to form a strong, leak-proof bottom region 58. By forming cup 52 as illustrated in FIG. 5, a recessed area 70 is created in the bottom of cup 52 on an opposite side of bottom blank 62 from the main container region of cup 52. Recessed area 70 permits insertion of a tool to press lip 64 and flap portion 66 to the lower region 67 of sidewall blank 60 and form the bottom seal.

In accordance with the present invention, the sidewall blank 60 is provided with relief formations at selected locations relative to the lower edge so as to overcome the twist or wrinkle effect discussed in the Background of the Invention, and improve the quality of the bottom region of the cup 52.

Referring now to FIGS. 4 and 6, the sidewall blank 60 is formed on front and back surfaces with a series of score lines 72 that extend upwardly and perpendicularly from the lower edge 60d. Preferably, the score lines 72 are equally spaced from one another and are of equal length.

FIG. 7 shows another embodiment of sidewall blank 60 wherein a series of slits 74 are formed therethrough adjacent the lower edge 60d. Again, the slits 74 extend upwardly and perpendicularly relative to the lower edge 60d, are preferably equally spaced from one another and are of equal length.

FIG. 8 shows a further embodiment of the sidewall blank 60 wherein a series of inverted V-shaped notches 76 is formed along the lower edge 60d. The notches 76 extend upwardly from the lower edge 60d, are preferably of equal size and preferably are equally spaced from one another.

The score lines 72, slits 74 and notches 76 collectively define relief formations at or adjacent the lower edge 60d of each sidewall blank 60. Such relief formations generally extend continuously across the length of the lower edge 60d. When deep bottom cups such as 52, FIG. 2 are formed using the sidewall blanks 60 with the relief formations formed along the lower edges 60d as described above, the undesirable twist or wrinkle effect is eliminated, and a smooth aesthetically pleasing external peripheral surface is formed in the lowermost region of the cup. The manufacture of such deep bottom cups using the sidewall blank 60 with such relief formations 72, 74, 76 has also been found to be beneficial in preventing leaks in the bottom of the cups.

While the invention has been described with reference to a preferred embodiment, those skilled in the art will appreciate the certain substitutions, alternations, and omissions may be made without departing from the spirit thereof. Accordingly, the foregoing description is meant to be exemplary only and should not be deemed limitative on the scope of the invention set forth with the following claims.

Claims

1. In a two piece cup formed by a sidewall member having an upper edge, a lower edge and pair of opposite side edges overlapped and sealed along an overlapped side seam. and a bottom member sealed along the lower edge of the sidewall member, the improvement comprising: a plurality of relief formations provided at or adjacent the lower edge of the sidewall member.

2. The improvement of claim 1, wherein the relief formations extend upwardly from the lower edge.

3. The improvement of claim 1, wherein the relief formations extend perpendicularly from the lower edge.

4. The improvement of claim 1, wherein the relief formations are equally spaced from one another.

5. The improvement of claim 1, wherein the relief formations extend continuously along a length of the lower edge.

6. The improvement of claim 1, wherein the relief formations are formed as a series of score lines.

7. The improvement of claim 1, wherein the relief formations are formed as a series of slits.

8. The improvement of claim 1, wherein the relief formations are formed as a series of inverted V-shaped notches.

9. The improvement of claim 1, wherein the relief formations are of equal size.

10. A two piece cup comprising: a sidewall member having an upper edge, a lower edge, a pair of opposite side edges overlapped and sealed together along an overlapping side seam; anda bottom member sealed along the lower edge of the sidewall member,wherein a plurality of relief formations are formed at or adjacent the lower edge of the sidewall member such that undesirable wrinkle effects normally incurred during bottom formation of the cup which lead to leaking problems are prevented.

11. A cup forming sidewall blank comprising: a piece of flexible sheet material having an upper edge, a lower edge and pair of opposite side edges wherein the lower edge is provided with a series of spaced apart relief formations extending upwardly therefrom.

12. The sidewall blank of claim 11, wherein the sheet material has a generally trapezoidal shape.