GB2068214A - Plastic case - Google Patents

Abstract

A plastic case or cabinet, particularly a television receiver case, is formed by a continuous outer wall (1, 2, 3, 4) forming a closed band with rounded edges, the edges having reinforcements which comprise an inner wall (8, 9) and ribs (10, 11, 20), whereby at least two cavities are produced. Preferably the mould includes cores for (forming said cavities) of Be-Cu or other material having high thermal inertia. <IMAGE>

Description

SPECIFICATION Plastic case The present invention relates to plastic cases or cabinets obtained by injection molding, particularly for housing television receivers and the like.

It is known a technique to obtain by molding plastic cases or housing formed by a continuous and closed band defining the four sides of a parallelepiped container to which a front panel and a rear panel are subsequently applied to complete the case.

The edges of said case can be at right angles or rounded. When using rounded edges, as a recall to cases previously made by wood, possibly emphasized by an external covering reproducing the wood grains, the manufacturing presents a number of difficulties. As a matter of fact the edges constitute the most stressed portions under conditions of case impact and therefore they must be more shock resistant than the flat portions of the band. However simply thickening the wall of the band at the edges does not permit to get the wished mechanical properties of resistance since the structure brittleness increases with the thickness. Moreover it is not desirable for the molding that the case presents sections with a thickness significatively larger than the remaining portions because this would make the molding process more complex and would require a longer cooling time for these portions.

Therefore, the usual cases of this type used the traditional solution, directly derived from the manufacturing of wood cases, to apply small blocks having a prismatic shape and rounded triangular bases, glued at the edges after the molding. While this solution might the acceptable as for the case resistance, yet it complicates the manufacture steps requring additional parts, supplementary time and handwork and increasing the costs.

According to the invention there is provided a plastic case comprising a continuous outer parallelepidal wall forming a closed band with rounded edge having angle reinforcements, characterized in that said angle reinforcements are integral with the case, each of the reinforcement comprising an inner wall, transversely extending to the band, at a region surrounding the rounded edge and connected to the outer wall by at least three transversal ribs orthogonal to the outer wall thereby forming at least two cavities extending transversally.

The invention will now be illustrated in a non limiting embodiment with reference to the attached drawings, in which: Figure 1 is an axonometric view of a case according to the invention; Figures 2, 3, 4 and 5 are fragmentary sectional views of the case of the invention; Figures 6 and 7 are two angle scrap views of the case of the invention; and Figures 8 and 9 schematically illustrate the mold portions for building the angle reinforcements.

Referring to Fig. 1 a case is shown, such as a television receiver case; comprising a closed continuous band of plastic material forming side walls 1, 2 and upper and lower walls 3 and 4 of the case, respectively. Said case is obtained by a single molding of a suitable plastic material such as shock-adsorbing polystyrene. For simplicity not all the components of the case, such as vent openings, support projections, stiffening ribs or mounting elements, etc. are illustrated in the figure. In the interior of the case, at the edges, angle reinforcements 5 are built which are illustrated in ore details in Figs. 2 to 7, still referring to a television housing.

Said angle reinforcements comprise an inner wall formed by at least one flat portion 8 inclined both with respect to the vertical walls and the horizontal walls, and by at least one other portion 9, parallel to one of the outer walls. The reinforcement further comprises a rib 10, orthogonal to portion 8 of the inner wall and at least a rib 11 orthogonal to portion 9. The reinforcement shown in the figures is applied to a case that provides for a recess 14 in proximity of a lower edge and consequently portion 8 of Fig. 5 terminates directly onto rib 1 2 of said recess without a horizontal portion such as portion 9 on the vertical side.However such a structure is not limiting as the reinforcements according to the invention can be carried out with two flat portions, respectively parallel to two adjacent sides of the case, and one or more ribs between said flat portions and the corresponding sides of the case (see Figs. 6 and 7).

As can be seen in Figs. 1 and 5, rib 11 (and the other one corresponding to rib 1 2 in the symmetric embodiment) extends transversally along the whole width of the band forming the case. However, about at the middle of the band width, an additional rib 20 is provided, longitudinal with respect to the band and extending along the whole reinforcement. On the contrary rib 10 is preferably shorter than the whole angular reinforcement 5 to make the molding simpler.

With the illustrated embodiment each angle reinforcement comprises two distinct spaced apart walls, connected by ribs on the whole forming at least four cavities (i.e. two cavities further transversely divided by rib 20). More particularly Figs. 2 and 3 show the two horizontal side walls sectioned along a central plane ll-ll whereas Figs. 6 and 7 show angle portions of the case. In said figures vertical ribs 1 5 and horizontal ribs 1 6 running along almost the whole band forming the case are more clearly visible. More particularly said supporting ribs extend along each side of the front and are broken only for openings and cuts to snap mount the front panel (not shown). On the contrary the back rib of the lower horizontal side is missing.Said supporting ribs are also built during the molding of the case employing suitable retracting plugs in the mold to obtain the necessary undercuts.

The presence of a chamber or flat recess 18 in the lower part of the case allows for receiving the bottom of the kinescope without enlarging the overall size of the case. Additional elements such as brackets, cuts, recesses etc.

are provided according to the type of television set and are not illustrated in details being different from each television case and not essential to the purposes of the invention. The above structure confers to the case a higher resistance against shock when compared with the use of reinforcing blocks since it eliminates the discontinuity at the parts junction and adsorbs the stresses by means of elastic deformation of the walls and the ribs.

However, if the solid reinforcements were merely replaced by hollow elements formed during the molding process, the manufacturing difficulties would only be transferred from the cooling of the mass of plastic material which constitutes the reinforcements to the angle plugs or mold pegs occupying the volumes of the cavities during the molding. More particularly said pegs, heated by the injected pasty material, could not be cooled enough by the usual cooling devices provided for the complete product. Consequently it would be necessary the modify the cooling system or to prolong the cooling times. In both cases additional costs would rise owing to the higher cost of the mold or to the reduced productivity, respectively.

On the contrary the process of the invention allows to overcome the above shortcomings.

More precisely the process of the invention provides for the use of pegs and mold parts built from a material having a large thermic inertia so that their temperature does not significantly rise during the molding phase.

Thus it is no longer necessary to extend the cooling step or provide for a special cooling of the angle portions. Referring to Figs. 8 and 9 there are shown the concerned mold portions which comprise mold matrix 21, supplying channel or runner 24, mold portions 28 and angle pegs 22, 23 for realizing the cavity.

According to the process of the invention the angle pegs and the mold portion 28 are built from a beryllium-copper alloy, for example the alloy known as BERILLBRONZ 2. Of course it is possible to employ other Be-Cu alloys or different alloys provided that their thermal or heat capacity is large enough to slow down the heating during the molding.

Whereas the invention has been described referring particularly to a television receiver case, it is not to be limited to this type of housing, the scope of the claims extending to modifications to the reinforcement shape and to the process.

Claims (8)

1. A plastic case comprising a continuous outer parallelepipedal wall forming a closed band with rounded edge having angle reinforcements, characterized in that said angle reinforcements are integral with the case, each of the reinforcement comprising an inner wall, transversally extending to the band, at a region surrounding the rounded edge and connected to the outer wall by at least three transversal ribs orthogonal to the outer wall thereby forming at least two cavities extending transversally.

2. A plastic case according to claim 1, characterized in that it provides an additional longitudinal rib, orthogonal the said transversal ribs and transversely extending to said band, placed at an intermediate position to define four transversal cavities.

3. A plastic case according to claim 2, chracterized in that said inner wall comprises a portion inclined with respect to both the horizontal and vertical sides of the outer wall and at least an additional portion parallel to one of the sides of the outer wall.

4. A plastic case according to claim 3, characterized in that it provides additional supporting ribs, obtained as undercuts in the molding process, projecting from the inner surfaces of the band and extending along the sides of the case.

5. A plastic case according to claim 4, characterized in that the supporting ribs in the front part of the case are provided with slots and cuts for snap mounting a front panel.

6. A process for injection molding a plastic case according to any of claims 2 to 5, characterized in that the mold portions for forming the cavities comprise mold pegs and elements built from a material having a large thermic inertia, such as a beryllium alloy and in that the mold is cooled after the injection of the pasty plastic material.

7. A process according to claim 6, characterized in that said beryllium alloy is a beryllium-copper alloy.

8. A plastic case, particularly for housing a television receiver, substantially as disclosed and illustrated.