Patent Application
20070228125
This is directed to a shipping container and the blanks for the container.
One type of container used as a shipping container is a regular slotted container known as an RSC. It is the blank 10 shown in
In forming the container for use, the container is opened from a lay-flat position and the lower closure flaps 19, 20, 23 and 24 are folded in and fastened together. The container is filled and the upper closure flaps 17, 18, 21 and 22 are folded in and fastened together. The top and bottom end panel closure flaps are usually covered by the side panel closure flaps.
For storage and transport the containers are stacked several high so stacking strength is necessary. A container should hold the containers above it without transferring the load to the contained product and its deformation should be minimal.
A corrugated container has a wall made of central flutes made of corrugating medium held in place by outer liners glued to the flutes. The flutes will normally extend vertically in the filled container to provide stacking strength. The actual stacking strength will depend on the size of the flute and the weight of the corrugating medium and the weight of the liners.
There are several size flutes. Some flute sizes are A flute which has 36 flutes per lineal flute and is 3/16 inch from flute tip to flute tip; B flute which has 51 flutes per lineal flute and is 3/32 inch from flute tip to flute tip; C flute which has 39 to 42 flutes per lineal flute and is 9/64 inch from flute tip to flute tip; and E flute which has 96 flutes per lineal flute and is 3/64 inch from flute tip to flute tip.
Basis weights for corrugating medium are from 16 to 40 pounds per thousand square feet. Basis weights for liner are from 20 to 96 per thousand square feet.
It should be understood that the higher basis weights increase the cost of a container.
The stacking strength may also be increased by using multiwall board. The board may be double wall with an external liner, a corrugated medium, a central liner, another corrugated medium and another outer liner. The board may be triple wall with an outer liner, a corrugating medium, an inner liner, a second corrugating medium, another inner liner, another corrugating medium and another external liner. The medium may be any flute size and the weights of the various elements may be the same or different. Again, the addition of the additional material increases the cost of the container.
After much research, and many trials it has been discovered that there is a simple way of increasing the stacking strength of a container without increasing the basis weight of the various elements of the container, or increasing the number of walls of the container.
The blank 30 for the container lid has a central panel 31 and four side panels 32 attached to the four sides of the central panel 31 by score lines 33. There are no tabs attached to the side panels 32. The blank is made of solid fiberboard having a basis weight of 50 to 400 pound per thousand square feet.
The blank 40 for the container body has side walls 41, 42, 43 and 44 and attachment panel 45 connected by score lines 46, 47, 48 and 49. The attachment panel 45 is attached to the outer edge of side wall 41.
The body usually is formed into a lay flat condition at the corrugated plant by gluing the attachment panel 45 to the outer edge of the inner side of side panel 41.
At the point of use the container can be formed by hand or by machine.
In the method of forming the container, the side walls 41,42, 43 and 44 will be squared so that two opposing side are substantially parallel. The walls will form a rectangular tube. The score lines of the lid 30 will be aligned with the outside of the side walls of the body. Glue will be placed on the panels 32. The glue may be placed on the panels 32 while the lid is being moved into position for the alignment step, during the alignment step, the seating step or after the body and lid have been aligned and seated. The panels will then be folded up around the side walls and adhered to the side walls.
In one embodiment the side walls 81′, 82′, 83′ and 84′ will be squared so that two opposing sides are substantially parallel. The side walls will form a rectangular tube. The tube will be horizontal. The lid 100 will be moved vertically into alignment with the body. Glue will be placed on the lid side panels during that movement. A mandrel will be inserted into the container body and move the body toward the lid until the side walls are seated on the lid and the sides of the side walls are aligned with the lid score lines. The mandrel will carry the body and lid will through a die cavity which will bend the lid panels around their score lines and place the lid panels against the container side walls, holding the lid panels against the side wall long enough to adhere the lid panels to the side walls.
The container will be filled with product and a lid placed on the top of the container. The top lid may have the design shown in
The upper lid may be loose, or the lid may be attached to the container.
The container and lid are shown as being four sided. The container and lid may have any number of sides. In any configuration the side walls of the container will fit into the crushed area of the upper and lower lids.
Embodiments of the present invention have been tested for stacking strength and for side deformation. In the tests the containers were filled with tennis balls.
In one test an embodiment was compared to an RSC. Both containers were single wall using a 26 pound C flute corrugated medium and a 35 pound liner glued to both sides of the flutes. The containers were 24 inches long, 15 inches wide and 15 inches deep. The maximum compression load for the RSC was 600 pounds. The maximum compression load for the container with a 90 pound fibreboard glued lid was 1390 pounds. The deformation of the side walls at maximum load for the RSC was 0.34 inches. The deformation of the side walls of the container with a 90 pound fibreboard glued lid at maximum load was 0.1 inches.
In another test an embodiment was compared to an RSC. Both containers were double wall using a 35 pound liner glued to one side of a 26 pound B flute corrugated medium, a 35 pound center liner glued to the flutes on both sides, a 26 pound B flute corrugated medium and a 35 pound liner glued to the those flutes. The containers were 24 inches long, 15 inches wide and 15 inches deep. The maximum compression load for the RSC was 1500 pounds. The maximum compression load for the container with a 90 pound fibreboard glued lid was 3000 pounds. The average deformation of the side walls at maximum load for the RSC was 0.57 inches. The deformation of the side walls of the container with a 90 pound fibreboard glued lid at maximum load was 0.13 inches.
While embodiments of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.
