Patent Publication Number: US-10786931-B2

Title: Core mold and a method of use in creating a pallet with a curved opening

Description:
This application is a divisional application claiming priority to U.S. application Ser. No. 15/998,607, filed Aug. 21, 2018, incorporated herein in its entirety. 
    
    
     A mold core for a rotomold and a method of use for creating a curved opening in the rotomolding of a pallet is disclosed. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a perspective view of a pallet; 
         FIG. 2  is a side view of the pallet of  FIG. 1 ; 
         FIG. 3  is another side view of the pallet of  FIG. 1 ; 
         FIG. 4  is an underside view of the pallet of  FIG. 1 ; 
         FIG. 5  is a pallet jack; 
         FIG. 6  is a cutaway side view of the pallet; 
         FIG. 7  is a side view of a mold core; 
         FIG. 8  is a figure showing the radius and noncentric circles that would be formed by the of the bottom section and top section of the mold core; 
         FIG. 9  is a side view showing the mold core inserted into the mold, as the plastic hardens around it; 
         FIG. 10A  is a side view showing the mold core as it is being withdrawn from the opening formed by the mold; 
         FIG. 10B  is a side view showing the mold core as it is further withdrawn from the opening formed by the mold; 
         FIG. 11  is an overhead perspective view of two mold cores positioned before the openings of the central mold; 
         FIG. 12  is an overhead view of the mold in the frame 
         FIG. 13  is a perspective view showing the fit of the mold core base with the central mold for the pallet; 
         FIG. 14  is a front perspective view of the frame door as it is attached to the mold; 
         FIG. 15  is a side view of the frame doors in the closed postion against the frame and the central mold; 
         FIG. 16  is a perspective overview of one embodiment of the central mold; 
         FIG. 17  is an overhead view of the lid of the frame of the mold; 
         FIG. 18  is an overhead view of the frame locked and surrounding the mold; 
         FIG. 19  is a perspective view of an alternative embodiment of the mold. 
     
    
    
     The figures depict various embodiments of the described methods and system and are for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the methods and systems illustrated herein may be employed without departing from the principles of the methods and systems described herein. 
     DETAILED DESCRIPTION OF THE EMBODIMENT 
     The present disclosure is for a mold core that is used in a rotomold to form the openings  3 ,  4 ,  13 ,  14 ,  15 ,  16 ,  17 ,  18  of a pallet  5 . 
     Integrally a molded pallet  5  has a top deck  7 , and a bottom support section  12 . The bottom support section  12  has four walls or sides  8 ,  9 ,  10 ,  11 . On at least one of the sides, there are two openings  3 ,  4 . In another embodiment, there are two openings  3 ,  4 ,  13 ,  14 ,  15 ,  16 ,  17 ,  18 , on each side  8 ,  9 ,  10 ,  11  of molded pallet  5 . In another embodiment, there are two openings on two opposing sides. There are four corner posts  19 ,  20 ,  21 ,  22 . Furthermore, there is a bisecting post  23 ,  24 ,  25 ,  26 , between the openings on each side  8 ,  9 ,  10 ,  11 . Additionally, in another embodiment on an underside  27  of the pallet  5 , there is an integrally molded support block  28 , generally positioned in the middle of the  27  of the pallet  5 . In yet another embodiment, there are further support blocks  29 ,  30  positioned integrally and behind two of the bisecting posts. In another embodiment, there are support blocks integrally molded and behind all of the bisecting posts (not shown). 
     For further strength, runners  32   33 ,  34 ,  35 ,  36 ,  37 ,  38 ,  39  are integrally molded above and as part of the rim, and are positioned in said openings  3 ,  4 ,  13 ,  14 ,  15 ,  16 ,  17 ,  18 . 
     Hand operated pallet jacks  40  are used to move the pallets from one location to another. Because the pallet jack  40  has wheels that must go through the openings  3 ,  4 , or  3 ,  4 ,  13 ,  14 ,  15 ,  16 ,  17 ,  18 , it is advantageous that the runners  32 ,  33 ,  34 ,  35 ,  36 ,  37 ,  38 ,  39  of the rotomolded pallet be curved, so that the wheels  41 ,  42 , are not going over a rectangular bump. In order for the runners to be molded in a curve, however, a particular mold core  50  is used to form the openings. The mold core  50  can be made out of aluminum, stainless steel, steel, or any other appropriate metal. It could even be made out of a resin. This mold core  50  has or is made up of, at its distal end, a base assembly  51 . The base assembly  51  can have a base  52  and flange  53  which are connected to each other. The base  52  positions the core in the mold. In one embodiment, the base  52  and the flange  53  are integral to one another or cast together, or cast with the entire mold  50 . 
     Referring now to the active part  57  of the mold  50 , a bottom section or bottom side  54  of the mold core  50  is convexly curved and in one embodiment is integral with the base assembly  51  at its distal end. When the mold core is inserted into the open side  55  of the mold and when the liquid or powdered plastic is added and melted, the curved runners will form under the bottom side or section  54  of the mold core. 
     The mold core  50  also has two sides  55 ,  56  that are integral with the bottom section  54  and with the base assembly  51  and their ends. There is also a front side or face  82  to which the sides  55 ,  56  are attached at their proximal ends. In one embodiment, the active part of the mold is integral. 
     The active part  57  of the mold core  50  also has an upper section  58 . This upper section  58  is connected to, and in one embodiment integral with the base assembly  51  at its distal end and to the top of sides  55 ,  56 , at the sides  59 ,  60 . This upper section  58  has a convex curve  73 ; however, this convex curve  73  is not in parallel with the convex (lower) curve  72  of the bottom section  54 . 
     As the plastic work hardens, or strain hardens, the plastic shrinks around the mold. If curves  72  and  73  are parallel, then the shrinking plastic would grab the mold core  50  and make it difficult to remove from the molded object. Consequently, so that the mold core  50  does not get embedded or trapped in the openings  3 ,  4 ,  13 ,  14 ,  15 ,  16 ,  17 ,  18  by the hardened plastic, the upper curve  73  is oriented around a different center of rotation  71  than that of the center of rotation  70  of the convex (lower) curve  72 , thereby creating a core geometry where the upper curve  73  and the lower curve  72  are not parallel. If the center of rotation of the upper curve  73  is outboard of the center of rotation of the lower curve  72 , the two curves are divergent towards the base assembly  51 . This geometry creates a “rotational draft.” 
     Of course, the radius  74  of the convex curve  73  of the upper section  58  is longer than that of the radius  75  of the convex curve  72  of the bottom section  54 . It should be noted that different customers for the pallet have different needs for different sized pallets, differently curved floors, etc., and consequently the radii and the center of rotation of the curves vary. It should be noted that in one embodiment, the height  76  of the proximal end or face  82  of the mold core  50  is less than the height  77  of the distal end  83  of the active part  57  of the mold  50 . 
     The mold core  50  is inserted into a gap  78  in the central mold also known as the body of the mold  85 , and the plastic is heated and distributed around the mold core  50 . When it is time to remove the mold core  50 , the mold core is rotated out of the now molded opening  3 ,  4 ,  13 ,  14 ,  15 ,  16 ,  17 ,  18 . As the mold core is rotated out of molded opening, the upper section  58  with the convex curve  73  actually rotates away from the curve formed in the ceiling  79  of the opening, also known as the ceiling curve  79 . This allows for easy removal of the mold core from the molded opening. 
     In one embodiment, the mold core  50  has a hollow pass through  81  extending laterally through the entire mold core, from the proximal end or face  82  of the mold core  50  out through the base assembly  51 . This hollow pass through  81  allows for air flow or heat transfer along the length of the mold core  50 . The width of the mold core surrounding said pass through ranges from about ½″ to about 2″. 
     The process begins by obtaining the central mold or the body of the mold  85 . The central mold or body of the mold  85  is attached to or fitted into a main frame  100 . Attached to the main frame are rotatable or pivotable frame doors  90 . The frame doors  90  are connected to and pivot about by means of a pivot arm  120  which are attached to the main frame  100  by a hinge pin located at the center or rotation of the lower arc of the core. Cores are held in the open position for de-molding by a spring actuated locking pin  98 . The locking pin  98  has a handle  99 . A pivot arm lock  122  and a locking plate  121  provide support and control for the pivot arm  120 . 
     In one embodiment, a base assembly  51  of the mold core  50  is attached to a frame door  90 , with large screws or threaded bolts  91 ,  92 ,  93 ,  94 . In the embodiment shown, the frame door is bolted to the flange  53 . Furthermore, there can be at least two additional points of attachment  95 ,  96  of a middle cross bar  97  of the frame door  90  attaching the frame door  90  to the base assembly  51  of the mold core  50 . 
     In another embodiment, a long bolt  101  centered through the frame doors  90  connects and secures the frame door  90  to a female threaded receptor  102  which is part of and secured to the main frame  100 . Other smaller screws (for example screw  103 ) attach the base  51  or in one embodiment, the flange  53 , directly to the main frame  100 . In an alternative embodiment, the mold core  50  can be held in place by any other means known in the art, including clamps, shorter bolts, screws, etc. 
     The outer rim  104  of the central mold  85  has a door frame opening  103  and openings in the rim  104  which are filled when frame doors  90  containing the mold core  50  are closed. The top edge  105  of the base  81  and the door frame openings  103  complements and are filled by the base  81  while at the same time the active part of the mold core  57  is positioned against the central part  106  of the mold  85  There are a plurality of threaded holes  107  along the top of the edge  105 . These holes  107  will be used to seal the mold lid  108  of the central mold  85  to the frame  100 . More specifically, the mold lid  108 , shown in  FIG. 17 , fits over the central mold  85 . This mold lid  108  has a rim  109  with a plurality of holes  110  so that it can be attached and bolted down to the central mold  85 . The lid  108  is supported by the upper frame  111 . 
     As shown in  FIG. 18 , the lid is configured to attach to the central mold and the upper frame and the lower frame are attached. The holes  110  surrounding both the lid  108  and the threaded holes  107  along the top of the edge  105  can be used to attach and seal the mold and the lid or can be used to attach the upper frame  111  to the main frame while simultaneously securing the main mold  85 . Latches  112  positioned at each corner of the further allow for a locking of the frame. 
     The plastic powder or liquid used to form the mold is added prior to locking up the frame, or is added through distinct openings that rim into the mold. Once the plastic powder (usually PCV) is added, the frame is mounted into a rotomold which heats and rotates the mold in different axis so as to equally distributed the now melted plastic. Once the plastic begins to harden, it is cooled and removed from the frame for any further treatment such as trimming of excess plastic. 
     The mold core  50  can used in other molding processes, and not just for the creation of pallets. 
     Although the disclosure has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character—it being understood that the embodiments shown and described have been selected as representative examples including presently preferred embodiments plus others indicative of the nature of changes and modifications that come within the spirit of the invention(s) being disclosed and within the scope of disclosures(s) as claimed in this and any other applications that incorporate relevant portions of the present disclosure for support of those claims. Undoubtedly, other “variations” based on the teachings set forth herein will occur to one having ordinary skill in the art to which the present invention most nearly pertains, and such variations are intended to be within the scope of the present disclosure and of any claims to invention supported by said disclosure.