US2022770A - Pyrotechnic device - Google Patents

Description

Dec. 3, 1935. W, L. KANN 2,022,770

PYROTECHNIC DEVICE Filed April 6, 1955 Patented Dec. 3, 1935 UNITED STATES ATENT oFFicE 9 Claims.

This invention relates to pyrotechnic devices, and more particularly to such articles known in the trade as salutes and toy torpedoes.

It is a general object of the present invention to provide novel and improved pyrotechnic devices of the type mentioned and novel methods of manufacturing the same.

More particularly it is an object of the invention to provide pyrotechnic devices in which the 'explosive compound is enclosed in a mo-nolithic casing of hardened plastic material having the quality of breaking or shattering into iine particles as a result of the explosion whereby large flying parts are avoided.

Another object of the invention resides in the provision of a pyrotechnic device including a capsule enclosing the explosive compound and which is encased in an outer cover of plastic material formed thereabout while soft and permitted to harden.

A further object of the invention resides in the enclosing of a mass of explosive compound and detonating means within a monolithic plastic casing during the forming of the casing.

An important feature of the invention as applied to toy torpedoes resides in filling the capsule completely full of explosive material and some detonating agent such as gravel and then encasing it in a covering of plastic material and permitting the material to harden, and in so selecting this material that it shrinks materially on hardening to apply pressure on the walls of the capsule and compress the particles of gravel to render them immobile'under ordinary handling of the device, thereby eliminating the danger of premature explosions during shipment by shifting o-f the gravel particles in respect to each other.

Another important feature of the invention resides in certain methods of assembling the pyrotechnic devices wherein the explosive is placed,

in a capsule which is then supported or suspended centrally in a mold and molten plastic material poured into the mold and the supporting or suspending means removed before the plastic material hardens, thereby permitting the encasing of the capsule in a monolithic or unitary cover which will resist the expanding gases resulting from the explosion substantially uniformly in all directions to produce the maximum report and to better insure against the flying of large portions or segments of the casing.

Other and further features and objects of the invention will be more apparent to thoseskilled in the art upon a consideration of the accom- Figure 3 is a similar view showing the torpedo 15 V` after the casing has cooled and shrunk away from the walls of the mold and compressed the capsule and its contents; Y

Figure 4 is a central section through a modified form of torpedo; 20

VFigure 5 is an elevation of a capsule and fuse for a salute, partly broken away to show the contents; and

Figure 6 is a section of the salute capsule showing the casing formed by dipping. 25

Toy torpedoes and salutes must be manufactured with both a view to safety to the user and manufacturer as well as a low cost. To insure safety to the user, it is essential that the covering or casing shall not remain in large pieces 30 which might fly as a result of the explosion and inflict serious injury. To provide safety during manufacture and shipment, it is essential that the possibility of accidental explosion be reduced i to a minimum, and to provide low cost it is neces- 35 sary to eliminate insofar as possible manual operations and to'reduce the total number of operations to a minimum. The torpedoes and salutes of the present invention, when constructed according to the exemplary methods to be de- 40 scribed, meet all three of the requirements satisfactorily.

t will be understood that in the specification where the term salute is used, it refers to any explosive Ytoy which isY ignited by the use of a fuse 45 and in which the main or primary purpose is to place when the casing is violently impacted as by throwing it against a sidewalk, wall, or the like. The only difference in the two types of toys may be in the means for igniting the'explosivethe'z,

first requiring the application of fire and the second necessitating an impact or shock.

In the drawing, several methods and specic forms of torpedo and salute have been shown by way of example only. The torpedo of Figures 1, 2 and 3 consists essentially in four components, the outer casing (D, the capsule Il, the explosive compound I2, and the igniting means I3, which may be variously termed impact devices, ignition means, impact igniting means, or more simply gravel since that is the common ingredient used for the purpose.

The gravel and explosive compound are en-V closed in the capsule, which for conveniencemay comprise two telescoping parts as shown, and the whole is encased in the monolithic outer casing or cover, preferably of spherical configuration a1- though any desired outer form may be selected.

In the manufacture of a torpedo, the explosive material is first selected. It may consist of any suitable explosive composition such as commonly used in torpedoes of this type. A satisfactory composition for the purpose includes at least two ingredients, one an oxidizing agent and the other a readily oxidizable substance. The rst may be potassium chlorate and the second sulphur, but in most cases it isY preferred to add to these two ingredients a third or sensitizing ingredient such, for instance, as antimony sulphide. 'I'he proportionsof this ingredient control the sensitivity.

The impact igniting means may be any suitable hard granules, of an abrasive character if desired, but for the sake of convenience and cheapness, sized gravel is customarily used. It is preferred to have the size of the gravel such that but a few particles are in the capsule, for instance, not many more than six to ten.

The capsule Il may be formed of any suitable tenacious material which is bendable or exible and can b-e readily made and handled. A satisfactory form comprises a pair of telescoping paper or cardboard cups punched to the shape shown and one 4iitting over the other with sufficient closeness so that friction holds the parts together temporarily after they have been telescoped.

In the lling operation the smaller of the two cups isY supplied with the requisite amount of gravel, and explosive compound either pre-mixed,

or with appropriate proportions of the separate ingredients which will later be mixed by a tumbling process or in the normal handling operation of the torpedoes. For the purpose of this invention, it is desirable that the gravel particles substantially ll the cup so that when the cap or cover is applied, there is none or only a very small empty space l5 remaining-the smaller this space, the better. The explosive need not completely fill the interstices between the particles of gravel.

The covering material to provide the casing for the capsule has two functions, iirst, Yto. somewhat reinforce the capsule and hold the parts thereof together to provide a louder explosion, and second, to give a pleasing contour, size and appearance to the finished article. It is advan-l tageous that this covering be'substantially monolithic in order that there be no planes or areas of cleaving which will permit it to separate readily into several large particles which will fly. It is preferred to apply this casing by casting or molding it about the capsule, but it may also be applied by dipping the capsule into a molten mass in one o r a series of successive operations to build up the requisite thickness. Then again, the ma- For instance, the casing may well be made from rosin, stearic acid, parafn,

waxes of many forms and types, sulphur, pitch compositions, or any one or more of the above ingredientstogether with a iiller such as an inert ground pigment or other colored pigments as iron oxide, lead oxide, chromium oxide, zinc oxide; or llers which are inert and without substantial coloring characteristics, such as wood 20 iiour, ground paper, cellulose, or other suitable and cheap ingredients. Under certain conditions, mixtures as forinstance, clay and glue,

wood our and silicate of soda, and the like, may

be used. The main purpose is to obtain a composition for the. casing which is substantiallyn moisture-proof and which if heat softened is molten Vat a temperature not so high as to ignite the explosive composition when formed about the capsule, remembering that the cooling is rather rapid and the capsule oerssome protection. The

material should not be soft at anynormally en` countered atmospheric temperatures, norshould it be sticky. If not of the heat softened type, the

plastic material should be quick-drying. Pleasing colors are desirable but notressential and can be obtained by some of the iilling ingredients mentioned above. Y Y

The most important feature of the casing, however, is that itshould contract or shrink very materially on hardening from its molten or plastic 'st ate for two purposes, rst, in order to place the whole capsule under strong compressive stresswhich will cause it to engage the mass of explosive materialand gravel and hold the same substantially under Apressrureat all times, thus preventing substantial relative movement of the gravel particlesin respectY to each other and insuring Yaga'instrigr'ntion o f the explosive compound except V,upon Violent impact, which will displace the'gravel particles due to momentum thereof and/or to deforming the casing; and second, in order that it may separate cleanly from the "mold, if a mold isused. 4

In the molding operation, use is made of a lower mold 26 preferably having a vsemi-spherical upwardly extending cavity 2| and an upper mold portion`22 having a downwardly extending and correspondingly sized semi-spherical cavity 2 3. In order that the capsuleand its charge may be held centrally of the spherical cavity of the combined mold parts, the lower portion of the mold is providedrwith Vthree vertical holes 24 to accommodate the three slender metal pins 25Y which at their lower or outer ends are'secured to a carrying bar 26. The upper ends Vof, the pins` lie in a horizontal plane and are preferably arranged at the apices' of an equilateral triangle lessV in extent than the bottom area of the capsule.

' When the bar Tais positioned as shown in Figure l, the upper ends of these pinsare properly positioned to receive the loaded capsula,

after which the upper portion of the mold is put in position and secured and the molten plastic 3ol i material is poured in through the iillingV opening 30. During this operation entrapped air may escape through the openings 3l. As soon as the plastic material has been poured in to ll the mold as shown in Figure 2, the pins are withdrawn to the position illustrated in that View and the molten material allowed to close up the space recently occupied by thepins. In Figure 2 it will be seen that there is still a small space above the gravel and explosive and that thev plastic material completely fills the mold.

In Figure 3 the mold is shown after cooling of the plastic, which takes place very rapidly because of the chilling eect of the metal walls of the mold, so that actually the torpedoes can be removed very shortly after the pouring operation. The shrinking eifect of the plastic material causes it to draw away from the mold as shown at 32, leaving a bright, clean, shiny surface on the torpedo and entirely freeing it from the mold so that it can be readily picked out when the upper half of the mold is removed. Any sprue remaining, as at 33, may be broken or cut oiT as desired. The effect of the shrinkage of the material on the capsule may be noted in Figure 3, for it is shown as reduced in size and at all points in engagement with the material filling the same so that the gravel is held rigid under compression and relative movement of the particles thereof is prevented.

In Figure 4 is shown an embodiment of a torpedo which differs in some respects from that shown in Figures 1, 2 and 3 but which functions in the same manner. It contains the same capsule and charge, but as a rst covering for the capsule there is a layer 35 of extremely tenacious material preferably placed on the capsule by a dipping operation. It may comprise a plastic having bers incorporated therein or it may be some Very tenacious plastic, as for instance, rosin, combined with a plasticizer. If this material remains sticky for any appreciable period after dipping, the coated capsules can be thrown on a revolving or shaking table covered with some powdered material to prevent sticking of the capsules together. This extremely tenacious coating reinforces the capsule suciently to provide a complete torpedo insofar as explosive qualities are concerned, but for the purpose of giving it a suitable conguration and appearance and a sufficiently large size to be attractive to the purchaser, the outer covering or casing 36 is profrangible so that the very complete explosion re*Y sulting from the rupture of the tenacious casing will cause the outer covering to be broken into minute fragments so that none of them will fly and be potential sources of danger.

Since the inner coating can well be made waterproof, this outer casing 35 can be a simple mixture of glue and a ller such as powdered clay, sawdust, wood flour, cellulose, paper pulp, or the like. Under these conditions it will readily retain a coloring material either incorporated is left out and a fuse 40 inserted through one wall of the capsule, as shown in Figure 5, preferably prior to filling and assembling thecapsule parts. This fuse may stick out through the opening used for lling the mold and may be relied on to suspend the capsule centrally in the mold instead of 10 using the supporting pins 25.

Instead of having the fuse extend out through the lling opening where it might be in the way, particularly where machine lling is relied on, there can be provided at the junction of the two 15 molded parts grooves which combine to form a tubular passage for the fuse so that it can extend horizontally out from the top of the mold shown in Figure 1. The rigidity of the fuse is adequate even under these conditions to support the cap- 20 sule substantially centrally of the chamber in the mold while the mold is receiving its charge of plastic material through the opening as in the case of the torpedo. This construction permits the removal of the sprue more readily without 25 danger of damaging the fuse and insures a tighter engagement of the plastic material with the fuse for obvious reasons.

In the case of salutes, if it is desired to dip them, for instance, instead of molding the casing, 30 the fuse makes a suitable handle for the purpose, and satisfactory salutes, as shown in Figure 6, have been made by dipping once or a number of times into melted stearic acid colored if desired to give a pleasing appearance. If dipping is to be resorted to for torpedoes, they may be carried in baskets or otherwise suitably held during vthe operation.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a toy torpedo, in combination, a capsule of readily deformable material, explosive mixture and impact igniting means therein and means maintaining said capsule under such compression as to prevent shifting of the impact igniting means therein.

2. In a toy torpedo, in combination, a charge of explosive, impact igniting means mingled with said explosive and an enclosing capsule holding the conglomerate under suiicient pressure to prevent relative shifting of the igniting means under normal handling conditions.

3. In a toy torpedo, in combination, a charge of explosive, impact igniting means commingled therewith, an enclosing capsule closely surroundV ing the conglomerate and a plastic casing completely enclosing said capsule and holding it under compression sufficient to prevent relative shifting of the igniting means under normal handling conditions.

` 4.V In atoy torpedo, in combination, a charge of explosive, impact igniting means commingled therewith, an enclosing capsule closely surrounding the conglomerate and a casingformed Vcom- 55 pletely around said capsule, said casing being of a plastic material which. shrinks suiiiciently` on hardening to hold the conglomerate immobile.

5. A toy torpedo comprising, in combination, a mixture of gravel and an explosive composition, a completely enclosing capsule therefor closely tting the mass, a casing Vof a hardened plastic which will break into ne particles on explosion, said plastic having the propertyof shrinking onY hardening so that when applied to the capsule ploded on impact comprising in combination, a mass of explosive and gravel and a completely enclosing unitary casing formed and shrunk tightly thereabout.

9. A toy torpedo of the type adapted to be exploded on impact comprising in combination, a mass of explosive and gravel, a covering of tenacious material enclosing said explosive and gravel and contracting the same and a frangible casing over the covering to increase the size of the 10 torpedo.

WILLIAM L. KANN.

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