GB2101970A - Integral latching arrangement for moulded plastics containers - Google Patents

Abstract

A latching arrangement for an integrally moulded hinged-lid container comprises at least one latching device (10) in the form of interfitting male (11) and female (7, 12) parts moulded integrally with the container, e.g. a cassette box (1). The male part comprises a first finger (11) located within the container outer wall (8) and having a free end which is able to flex and is shaped to provide an undercut (12). The female part comprises a support member (7) defined by a skirt depending from the lid (4) and a second finger (15) having a curved profile (16) directed towards the support member. The free end of the finger (11) is forced past the curved profile of the finger (15) on closing the container and is positively retained between the finger (15) and its support member (7) by the undercut (12). <IMAGE>

Description

SPECIFICATION A latching arrangement for plastics storage containers The present invention relates to a latching arrangement which can be formed integrally with a moulded plastics article, such as a storage container. The invention has application, for example, to storage containers for tape cassettes, or cartridges.

It is common practice to mould storage containers for tape cassettes and cartridges from plastics material and, for ease of manufacture, and to maintain manufacturing costs at a minimum, it is preferable that the container has a minimum number of individual components. Thus, if possible, a plastics storage container formed as a one-piece moulding is preferred. One problem to be faced in producing a one-piece, moulded storage container is the provision of a positive latching arrangement, since the moulds used in producing the articles must be designed such that the article, when moulded, can be cleanly released. This requires that the article has no appreciable undercuts or projections, which, if moulded, could prevent the mould parts from being easily separated, and the article being readily removed.

An object of the present invention is to provide a latching arrangement for a moulded plastics article, which can be formed integrally with said article.

According to the present invention, such a latching arrangement comprises at least one latching device in the form of interfitting male and female parts moulded integrally with the plastics material article, the male part comprising a first finger, the free end of which is able to flex and is shaped to provide an undercut, and the female part comprising a support member and a second finger spaced therefrom which is also free to flex, said second finger having a curved profile directed towards the support member, said spacing and the dimensioning of the free end of said first finger being such that, when the parts are pressed together, the free end of the first finger is forced past the curved profile of the second finger and is positively retained between said second finger and its support member by the undercut of said first finger.

It will be appreciated that the invention includes within its scope a moulded plastics article, such as a storage container, having such a latching arrangement integrally formed therein.

In order that the invention may be readily understood, and further features made apparent, one embodiment of latching arrangement in accordance therewith, incorporated in a moulded plastics storage container for a video cassette, will now be described with reference to the accompanying drawing, in which: Figure 1 is a perspective view of the container, Figure 2 is a developed end view of the container as moulded, Figure 3 is an enlarged, fragmentally detail showing said latching arrangement, and Figure 4 is a vertical section through part of a mould for the container.

Referring to Fig. 1 the container is in the form of a rectangular shallow box body 1, one longitudinal side wall 2 of which is hinged along its lower edge to the bottom wall 3 of the box and is hinged along its upper edge to a lid 4. The lid 4 has a pair of support bosses 5 on its inner face adapted to fit, when closed, in the drive apertures normally provided in the video tape cassette. The side wall 2 constitutes a curved spine so that, when closed, the box has the appearance of a book.

Furthermore, the spine 2 has a flange 6 at each end thereof, which flanges lie adjacent respective end walls, when the box is closed, to act as dust seals.

The inner face of the lid 4 is formed with a marginal skirt 7, which is inset slightly from respective edges and, when closed, fits closely within the three other walls of the box, (i.e. the other side wall 8 and the two end walls 9), this skirt also acting as a dust seal.

In accordance with the invention, the box 1 is provided with a resilient latching arrangement comprising, in this embodiment, three latching devices 10. This latching arrangement will be described in more detail below.

Referring to Fig. 2, the box body 1 and lid 4 are integral and are formed as a one-piece moulding, the main split line being shown by the arrows AA-A'A'. Thus, as shown, to the lower side of the split line, the lower mould die plate provides the finished outer surface of the bottom wall 3 of the box 1, spine 2 and lid 4; the die may be formed to provide a patterned, or textured, finish to the moulded box.On the upper side of the split line, the upper die plate provides for the hinging together of the bottom wall 3, spine 2 and lid 4 by forming "V" shaped grooves 20 at the hinge positions, as well as providing for the side wall 8, end walls 9, flanges 6, skirt 7, and support bosses 5; it will be appreciated that these latter parts, in cross-section, are tapered slightly so as to be narrower at their outer edges, thereby to facilitate release of the box when moulded.

Referring now to Fig. 3, each resilient latching device 10 is formed integrally with the box during moulding and comprises interacting male and female parts. The male part is in the form of a finger 11, which is moulded close to the side wall 8 and extends upwardly from the bottom wall 3 and substantially parallel to said side wall. The free end of the finger 11 terminates at the level of the upper edges of the wall 3 and is flared to provide a curved undercut part 12.

The finger 11 is strengthened and positively located by the side wall 8 via a web 13. This web stops short of the upper edge of the side wall as shown to provide a space 14 in which the co-operating part of the skirt 7 can seat with the lid 4 closed. Also, by leaving it unsupported. the upper end of the finger 11 has a degree of flexibility. The female part of the device 10 is provided by said co-operating part of the skirt 7 and an adjacent further, relatively short, finger 15 moulded integrally with the lid 4. The free end of the finger 15 is flexible and provides a curved profile 16 directed towards the skirt 7.The spacing between the skirt 7 and finger 15 and the dimensioning of the finger 11 is such that, when the lid is pushed towards its closed position, the free end of the finger 11 is forced past the profile 16 of the finger 15 and is positively retained by its undercut between the finger 15 and the co-operating part of the skirt 7, which latter constitutes a support member.

Referring to Fig. 4, in vertical section, the mould comprises generally a back plate 21, ejector plate 22 having a number of ejector rods depending therefrom (not shown), upper mould bolster 23 and an upper die plate 24.

A lower die plate, and a bolster therefor, are also provided but not shown.

In order to produce the relatively small undercut 12 in the finger 11, as shown in Fig. 4, a forming pin 25 is carried by the ejector plate 22 and is machined to provide the front profile of said finger, including said undercut. In the moulding position, the pin 25 co-acts with the upper die plate 24 to form the finger 11. However, after moulding, and with the lower die plate moved away, a platten acts on the back plate 21 so that it moves downwardly, and thus causes an initial axial movement of the pin 25, against the action of biassing means 26, to release from the formed finger 11. Further downward movement of the back plate 21 causes corresponding movement of the ejector plate 22, so that the ejection rods push against the bottom 3 of the moulded box and thereby release the complete moulding; the finger 15 with its curved profile 16 and, if preferred, the co-operating part of the skirt 7 can be formed in a similar way using an appropriately machined forming pin.

Preferably, the plastics material used is polypropylene, which will provide an attractive finished product, and which has the further advantage of producing integral hinges 20 having a prolonged working life, particularly where the hinges are flexed as soon as the moulding operation has been completed.

Claims (8)

1. A latching arrangement formed integrally with a moulded article comprising at least one latching device in the form of interfitting male and female parts moulded integrally with the article, the male part comprising a first finger, the free end of which is able to flex and is shaped to provide an undercut, and the female part comprising a support member and a second finger having a curved profile directed towards the support member, said spacing and the dimensioning of the free end of said first finger being such that, when the parts are pressed together, the free end of the first finger is forced past the curved profile of the second finger and is positively retained between said second finger and its support member by the undercut of said first finger.

2. A moulded container comprising a body with an opening therein which is closable by a lid, the lid having a marginal skirt which fits closely within respective walls of the body, characterised in that the container incorporates at least one latching arrangement according to Claim 1, in that said first finger of the male part is formed with the body adjacent a said body wall, and in that the second finger of the female part is formed with the lid at a position where it will co-act with the first finger, said second finger being spaced appropriately from the marginal skirt of the lid, which latter constitutes the support member of the female part.

3. A moulded container according to Claim 2 in the form of a rectangular shallow box, one top face of which provides a lid which is hinged along the upper edge of one longitudinal side wall of the box body, said one longitudinal side wall being hinged along its lower edge to the bottom wall of the box body and being unconnected at its ends, the arrangement being such that said lid and one longitudinal side wall can both be hinged open, away from the body, said marginal skirt extending around the other longitudinal side wall and the two end walls only of the lid.

4. A moulded container according to Claim 3, characterised in that said first finger of the male part of the or each latching arrangement is formed close to its respective side wall and extends upwardly from the bottom wall substantially parallel with its side wall, the free end of said finger terminating level with the upper edge of its side wall and being flared to provide said undercut, and in that an integral strengthening web is formed between said finger and its respective side wall.

5. A moulded container according to Claim 3 or 4, in the form of a cassette box, the inner face of the lid being formed with a pair of appropriately spaced bosses to support the hubs of the tape spools.

6. A moulded container according to any one of claims 3 to 5, moulded in one-piece from plastics material, the hinges being formed as "V' '-shaped grooves and the main split line for the mould being along a single, flat plate which follows the line of the bottom wall of the box and said lid and one longitudinal side wall in their fully opened out condition.

7. A latching arrangement formed integrally with a moulded article arranged and adapted for use substantially as hereinbefore described with reference to, and as shown in, Figs. 1 to 3 of the accompanying drawings.

8. A moulded-cassette box formed, arranged and adapted for use substantially as hereinbefore described with reference to, and as shown in, Figs. 1 to 3 of the accompanying drawings.

.9. A mould which will produce moulded containers according to Claim 4, or cassette boxes according to Claim 8, incorporating a forming pin/ejector plate arrangement constructed and arranged as hereinbefore described with reference to Fig. 4 of the accompanying drawings.