BOX WITH LID

Description

TECHNICAL FIELD

This invention relates to lidded boxes, and more particularly to a box lid held in place by a frictional fit.

BACKGROUND

There are several ways to retain a lid on a box. Some lids are hinged, while others are completely loose and removable. Some require a latch or other hardware on the box to stay in place.

Even though boxes with lids have been around for at least centuries, improvements are always sought in how to configure such lids for ease of use in particular applications.

SUMMARY

One aspect of the invention features a box with a box body and a box lid assembly. The box body has walls defining between them an interior space, the walls including two opposing walls each having an interior wall surface bounding the interior space. The interior wall surfaces of the two opposing walls extend in parallel from an opening at one end of the box body and from corners of the box body. The box lid assembly is adapted to be removably received at the one end of the box body to cover the opening, and includes a rigid outer lid, a compliant interference fastener, and a rigid inner lid permanently secured to the rigid outer lid with the interference fastener sandwiched between the rigid outer lid and the rigid inner lid. The rigid outer lid has an edge region positioned to bear against the one end of the box when the box lid assembly is covering the opening. The compliant interference fastener is secured to the outer lid and has two ribs extending in opposite lateral directions and arranged to engage the interior wall surfaces with the box lid assembly received at the one end of the box body. The ribs of the interference fastener are of limited length so as to not extend to the corners of the box body when engaging the interior wall surfaces.

In some configurations, the walls of the box body include four walls with interior wall surfaces extending between and connecting four corners of the box body, and the compliant interference fastener has four ribs, each rib engaging a respective one of the interior wall surfaces with the box lid assembly received at the one end of the box body.

In some embodiments, each rib engages only less than half an overall length of its respective wall surface as measured between the corners of the box body. Preferably, the box lid assembly engages the box body only at the ribs and the edge region of the rigid outer lid when received at the one end of the box body to cover the opening.

In some cases, the ribs are of a first polymer material, the compliant interference fastener having a web of a second polymer material, more rigid than the first polymer material, over which the first polymer material is overmolded and which connects the ribs, with a portion of the web sandwiched between the outer lid and the inner lid.

In some examples, the box lid assembly defines an aperture in communication with the interior space, the aperture defined completely by the second polymer material of the compliant interference fastener.

In some cases, the web is at least partially disposed in a recess defined in the rigid outer cover.

The inner and outer lids may be permanently secured to each other by adhesive, and the box body and the inner and outer lids may all be of wood.

Preferably, the ribs each extend a distance, perpendicular to their length, about one-half a thickness of the rib measured in a direction of insertion into the box body.

The ribs are preferably of a polymer having a durometer of about 75 Shore A.

In some embodiments, the ribs engage only central regions of the interior wall surfaces. Preferably, each rib engages an interior wall surface over a continuous length of about ⅜ times an overall distance along the interior wall surface between opposing corners of the box body.

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of a box with a lid on the bottom of the box.

FIG. 2 is a cross-sectional view, taken along line 2-2 in FIG. 1.

FIG. 3 is an exploded perspective view of the box and lid assemblies.

FIG. 4 is a top (inside) view of the lid assembly.

FIG. 5 is a side view of the lid assembly.

FIG. 6 is a top view of a compliant interference fastener of the lid assembly.

FIG. 7 is a cross-sectional view, taken along line 7-7 in FIG. 6.

FIGS. 8A-8D are enlarged cross-sectional views of an interface between lid and box wall at one side of the lid, in different stages of engagement and separation.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Referring to FIG. 1, a box 10 in the form of a toy coin bank has a box body 12 and a removable lid assembly 14. The lid assembly is shown at the bottom of the box, forming a base upon which the box rests. Alternatively, the lid may be disposed at the top of the box body, with the box inverted. To give a perspective of the size, box 10 has an overall height H of about 100 mm.

Referring also to FIG. 2, box body 12 defines an interior space 16 between opposing walls 18 of the box body. In this example, the box body is of generally square cross-section, with four similarly sized walls 18 connected at four corners of the box. Each wall 18 has an interior wall surface 20, with the interior wall surfaces 20 of opposing walls 18 extending parallel from an opening 22 at one end of the box body (in this illustration, at the lower end of the box body). The interior wall surfaces completely bound the four sides of the interior space, extending all the way to the corners of the box body. An end frame 24 of the box 10 is mounted near the end of the box opposite the lid assembly 14 and defines an opening 26 therethrough for accessing the interior space 16 when the lid assembly 14 is in place.

The four walls 18 of the box body are formed of wood and are connected at right angle corners 28 defined by glued box joints, as shown in FIG. 3. The box body is assembled with end frame 24 constrained within grooves defined in each of the four walls 18, to make a dimensionally stable structure.

Referring to FIGS. 3-5, lid assembly 14 is comprised of three structural components overlaying one another and permanently joined together by adhesive. The box lid assembly 14 is adapted to be removably received at the end of the box body to cover the opening 22, and includes a rigid outer lid 32 of wood, a compliant interference fastener 34 of molded polymer nested in a recess 36 cut into the outer lid, and a rigid inner lid 38 of wood permanently secured to the rigid outer lid 32 with the interference fastener 34 sandwiched between the rigid outer lid and the rigid inner lid, to form the structure shown in FIGS. 4 and 5. The rigid outer lid 32 has an edge region 40 positioned to bear against the one end of the box when the box lid assembly 14 is covering the opening 22 (as shown in FIG. 2).

The compliant interference fastener 34 is secured to the outer lid 32 and has a total of four ribs 42, including two sets of two ribs extending in opposite lateral directions and exposed at the sides of the lid assembly. The four ribs 42 are arranged to engage the interior wall surfaces 20 of the box body (FIG. 2) with the box lid assembly 14 received at the one end of the box body, with each rib 42 engaging to bear against the interior wall surface 20 of a respective one of the four walls 18 of the box body. As seen in FIG. 4, each rib 42 is of a limited length L of only about 32 mm, whereas the distance between opposing interior wall surfaces is about 81 mm. In other words, the ribs are only about ⅜ as long as the interior wall surfaces against which they bear. The ribs 42 do not extend to the corners of the box body when engaging the interior wall surfaces, but leave substantial portion of each wall unengaged and unsealed. Thus, the ribs 42 function only as an interference fastening against the smooth interior wall surfaces to hold the lid assembly 14 on the box, and do not form any sort of seal.

Referring to FIGS. 6 and 7, compliant interference fastener 34 is molded of two polymers. A web 44 of ABS polymer 45 has a central hub 46 and four spokes extending out to an octagonal rim 48. TPU polymer 49 is overmolded onto the web at four of the eight segments of the rim to form ribs 42 of a durometer of 75 Shore A. The TPU is overmolded to fill apertures in the rim segments, thereby securely interlocking the solidified TPU to the ABS web. The hub 46 defines a 17 mm diameter central aperture 50 through the web, sized for inserting a finger to pull the lid assembly from the box. Hub 46 extends axially from the web and has an outer diameter sized to fit in respective openings in the inner and outer lids (see FIG. 3), such that the ABS resin of the web forms a smooth inner surface through the lid assembly.

FIGS. 8A through 8D sequentially show the engagement and disengagement of a rib 42 against an interior wall surface 20 as the lid assembly 14 is received on, and removed from, the end of the box. Beginning with FIG. 8A, as the lid assembly is set into the box opening, the ribs 42 first help to center the lid assembly 14 to the box body 12. Each rib 42 extends out beyond the interior wall surface 42 to form an interference fit. As the ribs are pressed into the box opening (FIG. 8B), the ribs 42 deflect away from the interior of the box, and stay in this deflected, stressed state as they slide along the interior wall surface until the outer box lid 32 rests against the end of the box body 12 (FIG. 8C). As the lid assembly 14 is pulled away from the box body 12 (FIG. 8D), the ribs 42 resist sliding along the interior box surfaces 20. Preferably the durometer of the rib, in relation to the static coefficient of friction between the rib and the interior wall surface and the amount of interference, is selected such that the rib deflection is reduced as the lid assembly is dislodged from the box body, and in some cases even inverted prior to being pulled from the box body.

In this example, the rib has a thickness of 1.0 mm along its length and extends from the adjacent TPU wall a distance of 2.0 mm. The edges of the ribs are molded to have a radius of about 0.3 mm, and to also have a radius of about 0.3 mm where it joins the adjacent TPU wall.

This provides a reasonably secure connection between lid assembly 14 and box body 12, while at the same time not forming any seal and leaving the entire opening of the box body unobstructed when the lid assembly is not in place. In other words, this fastening approach does not require any undercuts, overhangs, or special hardware at the box opening. Because engagement between ribs and the wall surfaces is only along a central portion of each wall and not near the corners, the frictional fit of the lid assembly to the box body is less impacted by slight angular misalignment.

While a number of examples have been described for illustration purposes, the foregoing description is not intended to limit the scope of the invention, which is defined by the scope of the appended claims. There are and will be other examples and modifications within the scope of the following claims.