GB2300901A - Pyrotechnic casing - Google Patents

Description

2300901 PYROTECENIC CASING The invention relates to a pyrotechnic casing

and is particularly, but not exclusively, provided as a pyrotechnic casing made from pressed cardboard and from a plastic material and it in suitable for use as a container for fireworks in the pyrotechnic industry. Such a pyrotechnic casing is also known as a casing for fireworks.

Hitherto, pyrotechnic casings or casings for fireworks constructed from two half -parts or half -casings made from pressed cardboard have been produced, which half-parts or half-casings, after the pyrotechnic charge has been deposited therein, are joined via their facing edges and are closed manually, covering said edges with is glued tapes or adhesive strips.

The pressed- cardboard casings are dangerous given that they usually have manufacturing irregularities or defects, normally in the taping, which are liable to give rise to spillage of their charge and, consequently, undesirable explosions, which converts them into an unsafe material. In addition, it is costly to produce them.

Other pyrotechnic casings have also been manufactured by means of heatmoulding of plastics. In the case of these casings, each of the two half -casings which form them have their respective edges provided with conjugate coupling means for attaching them closely together and, at least, one of the two half- casings is equipped, in its polar zone, with an axial tubing through which fire is transmitted to the inside of the casing.

The pyrotechnic casings manufactured by means of heat-moulding of plastic materials offer a higher level of safety in the event of a possible spillage of their charge, which may be attributed to the reliable fit between their half-parts. Nevertheless, their principal detractors cite their, on occasions, incomplete combustion and point out that this pollutes and contaminates the environment and leaves visible remains of their combustion on the ground.

An object of the invention is to produce a pyrotechnic easing made f rom pressed cardboard and plastic material, in which it is easy to place the charge and which can be closed in a simple, rapid and convenient manner, so that the final assembly in cheap and it is possible to guarantee complete safety of the finally finished product. Similarly, it is intended that the combustion which in required after explosion of the charge should not leave solid residues and is complete for the purposes required..

According to an example, a pyrotechnic casing is formed by two halfcasings of cardboard which can be opposed and coupled via their edges in order to form, together with their charge, a firework. Each half-casing has, at its opening, a rigid ring of plastic material with a peripheral groove which is suitable f or permitting close attachment with a conjugate recess means provided on the opposing half-casing.

Amongst other procedures, the rigid ring may be f ixed by means of heat-moulding at the opening and be partially embedded therein. The ring has a plurality of extensions, for example in the form of bare, braces or ties which are adhered, during moulding, to the inner wall of said half-casing.

The pyrotechnic casing has the feature, in at least one of the two halfcasings which form it, of the extensions being integral with a tubing which constitutes the wrapper for a fuse for transmitting the fire to the inside of the casing.

According to the aforesaid, it is desirable for it to be possible for the rigid ring to be attached cheaply to the opening of a half -easing made f rom pressed cardboard. By using plastic materials, a practical example for achieving the attachment consists in forming the ring by moulding the plastic material directly on the peripheral edge of the half-casing, whereby a portion of the material which form the ring is embedded in the gaps of the edge of the opening, facilitating attachment between cardboard and plastic.

In order yet further to secure the fastening of the rigid ring of plastic material to the edge of the pressed cardboard which forms the half-easing, without requiring the additional intervention of manual oper- ators, during the same heat-moulding operation it is convenient to provide the rigid ring with a suitable number of extensions which, for example when they cross over one another, facilitate the heat-forming of the ring on the half-casing and, whether they cross over one another or not, reinforce the attachment of the plastic material to the cardboard since, during the operation, they are adhered to the inner surface of the half-casing.

In the event that one of the two half-casings which give form to the pyrotechnic casing, when attached is together, has to incorporate a plastic tubing in order to constitute the wrapper for the fuse which transmits the fire to the inside of the casing, the operation of heatmoulding the plastic material on the half- caning of cardboard will clearly include, 'forming a single assem- bly, the rigid ring and the tubing, the extensions serving as an attachment bond between them.

Substantially, the thicknesses or other dimensions of each one of the plastic elements heat-moulded on each one of the half-casings which will form the pyro- technic casing, considered together or separately, must be calculated so that, when combustion of the half- casings of cardboard occurs, such elements also combust so that, after explosion of the charge, no solid residues remain.

Obviously, in order to achieve the attachment between two half-casings in order to form a pyrotechnic casing, according to the intention of the invention, it must be possible to close them simply, so that the final assembly is cheap and it is possible to guarantee com- plete safety of the finally finished product. This object of the invention is achieved by shaping a groove at the periphery of the rigid ring of one of the half-casings, designed to permit close attachment with a conjugate groove provided on the rigid ring in the other half- casing or at its opening.

In a preferred embodiment, according to the invention, the pyrotechnic casing is formed by two half casings of cardboard which can be opposed and coupled via their edges in order to form, together with their charge, a firework, and each half-casing has, at its opening, a rigid ring of plastic material which has, on its periphery. a groove arranged in order to permit close attachment with a conjugate recess means provided at the opening of the opposing half-casing.

The rigid ring has been fixed in the opening of the casing by heatmoulding and a part thereof is embedded therein.

The ring has a plurality of extensions which are adhered to the inner wall of the half -casing, during moulding.

In at least one of the two half -casings which form the casing, the extensions are integral with a tubing which constitutes the wrapper for a fuse for transmitting the fire to the inside of the casing.

By way of example, the accompanying drawings show two half-casings made from cardboard and from plastic material and a preferred embodiment of a pyrotechnic casing.

In the drawings:

Figure 1 shows a view in elevation, partially sectioned over one quarter, of a half-casing with an incorporated rigid ring and ready for forming a pyrotechnic casing.

Figure 2 shows a view in elevation, partially sectioned over one quarter, of a half -casing suitable for forming the pyrotechnic casing and on the inner wall of which extensions, integral with the rigid ring incorporated therein may be observed.

Figure 3 shows a view in elevation, partially sectioned over one quarter, of a pyrotechnic casing f ormed by two hal f - cas ings bas ed on the hal f - cas ing shown in. Figure 2, although the upper half -casing shows a tubing integral with the extensions and, therefore, with the rigid ring partially embedded in the opening thereof.

As shown in Figure 1, a half -casing (2) of cardboard has, at its opening (4), a rigid ring (5) of plastic material, the periphery of which shows, over its entire outer rim, a notch (6). The body of the ring (5) shows a projecting peripheral portion (7) embedded in the opening (4).

By examining Figure 2, it is clear that the rigid ring (5) may be extremely well supported, achieving better support on the opening (4) of the half-casing (2) when, during its formation by means of moulding, the extensions (8) have also been obtained, the latter being adhered, through the effect of the heat- moulding, to the inner wall of the half-casing (2) and, therefore, they is reinforce the attachment of the plastic material. to the cardboard.

With the aid of Figure 3, it is a simple matter to describe the pyrotechnic casing (1) suggested by the invention, in which both halfcasings of cardboard, the lower one (2) and the upper one (3), have been closely coupled via their edges after being filled with a pyrotechnic charge (not shown in the drawings) in order to form a pyrotechnic casing according to the invention.

This close coupling is possible because each half-casing (2 and 3) has, at is opening (4), a rigid ring (5) of plastic material provided, at its periphery, with a notch (6) which is suitable for permitting close attachment with a conjugate recess means (61) provided on the opposing half-casing (3). Also, as stated, this rigid ring (5) has been fixed by means of heat-moulding and is partially embedded, via its projecting periphery (7), in the opening (4) of either of the two half-casings (2 or 3).

To contribute to guaranteeing attachment of the rigid ring (5) to the opening (4) of the half-casings (2 and 3), extensions (8) have been heat-moulded together with the ring (5), said extensions being adhered, during moulding, to the inner wall of either of the said halfcasings (2 or 3).

During the heat-moulding of plastic material,carried out on the halfeasing (3), the extensions (8) form a single piece with the rigid ring (5), via one end, whilst, via the other end, they form a single piece with a tubing (9) which is axially centred with respect to the half-casing and constitutes the plastic wrapper for a fuse for transmitting the fire to the inside of the casing. Said tubing (9) shows a cardboard tube (10) inside, in this instance also adhered to the assembly during the moulding operation.

Clearly, the extensions (8) projecting from the rigid ring (5) could cross over one another, for example in the arch part of the spherical half -casings (2) shown in the figures. However, they could also project from the is ring (5), facing towards the inside of the half-casing (2) without crossing over one another and until they achieve the lengths which are required in each case. it would also be possible to replace the extensions (8) which are, on occasion, formed as bars or braces, with framed cages or the like, for an identical purpose.

The invention has been described on the basis of the embodiment illustrated. Clearly, it is possible to modify details and/or to replace certain elements or arrangements by others which are equivalent or to add complementary devices of known type without thereby departing from the scope of the invention.

Claims (10)

1. 7 1. A pyrotechnic casing comprising at least two open partcasings capable of being brought together to accommodate a charge in order to form a firework, wherein interengageable surface formations are provided on the part-casings for coupling them together.
2. 2. A pyrotechnic casing according to Claim 1 comprising two half casings.
3. 3. A pyrotechnic casing according to Claim 1 or 2 wherein the partcasings are made of cardboard.
4. 4. A pyrotechnic casing according to Claim 3 comprising two half-casings of cardboard which can be opposed and coupled via their edges.
5. 5. A pyrotechnic casing according to any preceding claim wherein each part-casing has, at its opening, surface formations in the form of a rigid ring of plastic material provided with a peripheral groove which is suitable for permitting close attachment with a conjugate recess means provided on an opposing part-casing.
6. 6. A pyrotechnic casing according to Claim 5, wherein the rigid ring is fixed by means of heat-moulding and is partially embedded in the opening of the part-casing.
7. 7. A pyrotechnic casing according to Claim 5 or 6, wherein the rigid ring, which is fixed by means of heat-moulding and 8 is partially embedded in the opening of the half-casing, has a plurality of extensions which are adhered, during heatmoulding, to the inner wall of said half-casing.
8. 8. A pyrotechnic casing according to Claim 7, wherein in at least one of the part-casings, the extensions are integral with a tubing which constitutes the plastic wrapper for a fuse for transmitting a flame to the inside of the casing.
9. 9. A pyrotechnic casing substantially as hereinbefore described, with reference to and as illustrated in any one of the accompanying drawings.
10. 10. A casing according to any preceding claim loaded with a charge to form a firework.