Patent Publication Number: US-2012043374-A1

Title: Sidewall blank for substantially eliminating twist in deep bottom containers

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application relates to and claims priority of U.S. Provisional Patent Application Ser. No. 61/376,001, filed Aug. 23, 2010. 
    
    
     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  60   a,    60   b,  an upper curved edge  60   c  and a lower curved edge  60   d.  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  60   a,    60   b  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  60   d.  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  60   d.  Again, the slits  74  extend upwardly and perpendicularly relative to the lower edge  60   d,  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  60   d.  The notches  76  extend upwardly from the lower edge  60   d,  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  60   d  of each sidewall blank  60 . Such relief formations generally extend continuously across the length of the lower edge  60   d.  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  60   d  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.