Retainer for Box Lid

Description

BACKGROUND

The use of corrugated cardboard boxes for shipment and storage is ubiquitous. The most common type uses eight slots and twelve folds to transform a sheet of cardboard into a rectangular box. The resulting box has four flaps that fold in to form the lid and four flaps that fold in to form the bottom. Two flaps hinged at the sides fold to lie in the plane of the top and abut each other when closed. Two flaps hinged to the ends fold in to lie in the plane of the top but do not reach each other to abut. The end flaps are folded in before the side flaps and lie inside the side flaps when the box is closed.

When the boxes are delivered to the user, they are partly folded but still flat. The user finishes erecting the box. Because the cardboard resists folding, the unrestrained flaps of a finished box remain partly open. Tape, glue, or staples are often used to close the box for shipment or for storage without access to the contents. The act of opening destroys these means of closure and may damage the box.

When repeated access to the stored contents is desired, a re-usable means of keeping the flaps closed is needed.

U.S. Pat. No. 3,381,883A Sani-seal box closure clip

JP3106445U Cardboard box clip

Jps6193044AForm of clip made of resin for sealing corrugated box

AllenField Co. offers for sale a Box Flap Closure that grasps both of the side flaps. It is a strip of plastic with slots for the side flaps at both ends. It is strong enough to hold the flaps mostly closed against the resistance of the cardboard at the folds. See: https://www.allenfield.com/product/box-flap-closure/

Etsy offers for sale a Cardboard Box Clip that grasps both of the side flaps. It is a strip of plastic with slots for the side flaps at both ends. It is strong enough to hold the flaps mostly closed against the resistance of the cardboard at the folds. See: https://www.etsy.com/listing/1232140064/cardboard-box-clip?gpla=1&gao=1&&utm_source=google&utm_medium=cpc&utm_campaign=shopping_us_e-home_and_living-storage_and_organization-boxes_and_bins-other&utm_custom1=_k_EAIalQobChMIh9ng4YvCggMVhhatBh1qGgxfEAQYBCABEgLXd_D_BwE_k_&utm_content=go_12563207656_123128353601_507186593263_pla-307130480624_c__1232140064_12768591&utm_custom2=12563207656&gclid=EAIalQobChMIh9ng4YvCggMVhhatBh1qGgxfEAQYBCABEgLXd_D_BwE

The AllenField and Etsy closures are of very similar design and share the same weaknesses. If the slots grasp the flaps too tightly, they are difficult to install because the slots lie in the same plane and the partly closed flaps do not. Excess slot width to make installation easier fails to keep the flaps at the plane of the box top after installation. AllenField and Etsy closures grasp only the side flaps.

SUMMARY

In the field of packaging, rectangular boxes having four flaps for closure are ubiquitous. Opening a box which is held closed with staples, glue, or tape damages the box and/or said staples, glue, or tape thus making re-closure inconvenient.

State of the art Cardboard Box Clips and Box Flap Closures engage only the two side flaps. Engagement of not only the two side flaps but also an end flap by the foot and prong of the invention provides a more secure closure.

One embodiment of the invention uses a single length of wire bent to form all of the parts. Plastic could be used for other embodiments.

BRIEF DESCRIPTION OF DRAWINGS

The drawings show an embodiment using a single bent wire.

FIG. 1. shows a top view of the Retainer standing alone.

FIG. 2. Shows a top view with portions of the side flaps.

FIG. 3. Shows a side view of the Retainer standing alone.

FIG. 4. Shows a side view of the Retainer grasping the side and end flaps in section.

FIG. 5. Shows an end view of the Retainer standing alone.

FIG. 6. Shows an end view of the Retainer grasping the side and end flaps in section.

FIG. 7. Shows a rectangular cardboard box with flaps.

REFERENCE NUMERALS

• • 1. Foot
  • 2. Bar
  • 3. Spacer
  • 4. Prong
  • 5. Guide
  • 6. Side flap of box
  • 7. Side flap of box
  • 8. End flap of box.
  • 9. End flap of box

DETAILED DESCRIPTION

The closure is complete when all four of the flaps 6, 7, 8, 9 are constrained to lie at the plane of the box top. The plane of the box top is defined by the top edges of the box sides and ends where the flaps 6, 7, 8, 9 are attached and folded.

When the Retainer is in place FIG. 2, FIG. 4, FIG. 6., the foot 1 bears on the top surface of the side flaps 6, 7 and urges them downward into contact with an end flap 8 or 9. The prong 4 bears on the bottom surface of the end flap 8 or 9 and urges it upward into contact with both side flaps 6, 7. When the bottom surface of the side flaps 6, 7 are held against the top surface of the end flap 8 or 9 at the plane of the box top, the closure is complete. For the most secure closure, two Retainers may be used at the edges of both end flaps 8, 9. The bar 2 holds the spacer 3 in position relative to the foot 1 and sustains the forces and moments that urge said foot 1 and said prong 4 together. The spacer holds the prong 4 in position to bear against the bottom surface of the end flap 8 or 9. During installation, the tip of the guide 5 lies below the edge of the end flap 8 or 9 and makes certain that the edge of the end flap 8 or 9 enters the space between the foot 1 and the prong 4. The space between the foot 1 and the prong 4 is approximately two thicknesses of cardboard.

Installation Procedure

• • 1. By hand, fold the end flaps 8 and 9 to the plane of the box top.
  • 2. By hand, fold then hold the side flaps 6 and 7 to the plane of the box top.
  • 3. Insert the prong 4 and spacer 3 between the edges of the side flaps 6, 7 bringing the foot 1 and bar 2 into contact with the top surface of the side flaps 6, 7. FIG. 2.
  • 4. Slide the Retainer toward the end of the box until the spacer touches the edge of the end flap 8 FIG. 4.

Removal Procedure

Removal is the reverse of installation.

CONCLUSION

The previous state of the art is exemplified by the commercial offerings of AllenField and Etsy which employ a double-ended clamp to hold the two side flaps near the same plane.

By holding the two side flaps and an end flap together, the Retainer invention not only uses a different principle but also provides a more robust closure.

The Retainer may be installed and removed many times without damaging the Retainer or the box flaps.