Method of forming a box or box element of plastic material

Details Method of forming a box or box element of plastic material Method of forming a box or box element of plastic material

2001-04-17

2003-12-23

Ortiz, Angela (Department: 1732)

Plastic and nonmetallic article shaping or treating: processes

Direct application of electrical or wave energy to work

Utilizing electrostatic charge, field, force

C264S259000, C264S275000

Reexamination Certificate

active

06667004

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a box and to an insert for a box, each made up of at least two elements. The elements are made of molded plastic material and hinged to each other via at least one hinge mechanism. In the case of a box, the two elements can be identified as the bottom of the box and the cover of the box.
The features of the present invention is specifically designed for a flat box that is to receive a magnetic or optical medium for high density recording, and more specifically, for a compact disc (i.e., a digital audio disc). The invention is useful with other types of boxes, capable of containing various types of articles.
2. Description of Prior Art
Conventional boxes for storing items such as compact discs essentially comprise two elements, namely a bottom and a cover, which are hinged to each other about a hinge mechanism. Both elements are made of rigid transparent plastic material that is generally injected-molded such as, for example, clear polystyrene.
One of the elements carries two lateral studs which engage in openings provided in the other element, thus forming a pair of stub axles in axial alignment to make up the hinge. A paper label is generally inserted inside each box element and can be seen from the outside because each of the elements is transparent. The label has information concerning the contents of the box. Generally, the cover element label is slid over the inside face of the cover wall and is held therein by lateral tab members. The label is sometimes replaced by, or associated with, a removable booklet. The disc is held in place in a molded tray of plastic material that is clipped in the bottom element, with the label being sandwiched between the tray and the bottom wall. The intermediate tray includes a central disc-retaining member made up of radially-deformable resilient fingers which engage the disc in the central opening of the disc. This retaining member is commonly referred to as a “rosette” or a “thimble”. Generally, the bottom label has two marginal flaps folded over at right angles that are placed against the inside faces of the sides of the bottom element. Information is provided on these folded-over flaps to be visible through the sides of the box when the box is stored in such a manner so as to allow the edge to be visible. Some of the disadvantages of the above-described box are that it is difficult and time consuming to manufacture and is relatively expensive. The three elements making it up, i.e., the bottom, cover, and intermediate tray, are manufactured separately by an injection-molding process, and they are subsequently assembled together. In addition to the assembly operation, there is the operation of putting the labels into place. Another drawback of know boxes is the fragility of the lugs carrying the lateral studs constituting the hinge, and giving rise to many rejects on the assembly line and breakages during use.
Great Britain Patent No. 2,185,710 describes a box made by injection molding talc-filled polypropylene. The box is provided with a label formed by a sheet, also made of polypropylene, which is integrated in the box by overmolding during the injection process. The bottom and the cover of that box are formed as a single piece. Furthermore, the bottom and cover are connected together by a hinge-forming zone that is weak. The polypropylene sheet covers the hinge zone in order to provide it with mechanical reinforcement and thus increase its strength characteristics. In this device, the label does not constitute the hinge, and it does not replace the hinge; it merely serves to reinforce it. A major disadvantage of this type of device is that the material forming the box needs to be a non-breaking flexible material since it needs to act as a hinge and must therefore withstand repeated flexing without breaking or cracking.
SUMMARY OF THE INVENTION
A primary object of the present invention is to eliminate the various disadvantages outlined above with regard to the prior art structures by presenting a box structure which, while still being competitive in price, and relatively simple to manufacture, has a hinge that is particularly robust, long-lasting and able to withstand repeated flexing without breaking or cracking.
Another object of the present invention is to make it possible to be able to use rigid and brittle materials, in particular clear polystyrene which has remarkable qualities of transparency in the type of box structure as described herein.
Still another object of the present invention is to provide a box, in particular a flat box for storing a compact disc, in which the disc is held in place without requiring the use of an intermediate tray, but is held directly in the bottom element of the box. In this respect, it should be observed that with conventional boxes, the presence of the label in the bottom element makes it impossible to mold the rosette directly into the bottom wall.
Still an additional object of the present invention is to provide a novel system for holding and supporting a disc in a box; inside the bottom element of the box; the box itself system making it easy to install and remove the disc.
Still an additional object of the present invention is to improve the legibility of information visible on the side of a box used for storing a disc.
The various objects of the present invention described above are achieved by the fact that the box or box element in accordance with the present invention includes a flexible sheet of synthetic material which is fixed to each of the two hinged-together elements that constitute the box by overmolding, the flexible sheet having an intermediate free zone which comprises by itself, the hinge of the box. Thus, since the hinge comprises solely the intermediate free zone, it is sufficient for the material of the sheet to be flexible, and to be capable of mechanically withstanding back-and-forth flexing. The specific nature or composition of the material used for the two box elements is not important. The only critical point is that on overmolding there must be surface adhesion compatibility between the material forming the sheet and materials forming the box elements.
Also, according to various aspects of the present invention:
(i) at least one of the elements possesses a plane main wall, at least one of the faces of which is completely or partially covered by a portion of the flexible sheet;
(ii) the plane main wall has weight-reducing openings that are also covered by the flexible sheet;
(iii) the flexible sheet is an informative label;
(iv) the elements are made of transparent plastic material, such as clear polystyrene;
(v) the flexible sheet is made of a transparent material;
(vi) the label-forming flexible sheet includes information on both faces; and
(vii) the flexible sheet is made of material having good mechanical strength while being compatible on molding with the plastic material forming the elements, the material preferably being, a polypropylene-polystyrene or a polyethylene-polystyrene composite.
When the present invention specifically relates to a box:
(i) one of the two elements is a bottom member and the second element is a cover member, and the two elements have complementary mutually engaging profiles disposed facing each other in an intermediate free zone, suitable for providing mutual guidance for the two elements while the box is being closed, and then for providing relative locking therebetween after closure;
(ii) both the box (bottom) element and the cover element each possesses a main plane wall, one of whose faces is completely or partially covered by a portion of the flexible sheet, and at least one of the main walls including a rim adjacent to the hinge and likewise covered by the sheet;
(iii) the rim is provided with a profile for mutual engagement; and
(iv) the sheet portion covers the rim and carries on its face informative marking visible through the transparent thickness of the rim, which rim is shaped to from a magnifying glass. The sheet can be fixed to the botto

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