EP0050380A1 - Device and process for the manufacture of blister-free explosive and/or propellant charges - Google Patents

Abstract

For the production of void-free explosives and / or propellant charges, an insulating sleeve (9) is provided, the radial heat transmission of which, in any cross-section, corresponds to the amount of heat released radially there by the solidification of the melt. The insulation cover (9) creates a void-free casting without subsequent supply of external energy (electrical heating, etc.), even with very small pouring openings (6a) in the casting (1). The required heat transmission in the insulation cover (9) can be achieved by using insulating parts (4, 5, 10) and / or cavities (11) with heat transfer media, e.g. Adjust the melt to the thermal conditions of the casting (1). Corresponding casting processes are based on targeted preheating and gradual cooling of the casting (1) together with the insulation cover (9).

Description

The present invention relates to a device according to claim 1 for the production of void-free explosives and / or propellant charges of predetermined spatial shape and composition by casting, the solidification process within the melt being progressively delayed from bottom to top, and to a method for producing these explosives - And / or propellant charges according to claims 9 and 10.

The previously known methods for producing explosive or propellant charges are carried out by pouring an explosive or fuel liquefied at elevated temperature into the corresponding shape of the ammunition object or cargo space. The formation of harmful cavities in the casting was prevented as far as possible by external heat supply around or in the top section. The corresponding devices for carrying out such casting processes require a relatively large amount of equipment and are difficult to control in their temperature behavior.

Heating boxes (CH-PS 389 449) or metallic heating rods (CH-PS 503 253 and DE-AS 1 796 168) are known for influencing continuous solidification of explosives.

It is therefore an object of the invention to provide a device and to specify a casting method which enables a blow-free casting, even with very small pouring openings, completely without supplying heat to the casting funnel which is difficult to control. Furthermore, complicated heating devices are to be saved; the cooling phase should be relatively independent of the ambient temperature.

According to the invention, this is achieved by a device in which an insulation sleeve is provided outside of the casting mold can be seen, whose radial heat transmission in any horizontal plane corresponds at least approximately to the radially flowing amount of heat released in the solidification of the melt in the cross-section located in the same horizontal plane.

According to the method according to the invention, the insulation sleeve including the heat transfer medium is heated in a first step for at least one hour to at least the melting temperature of the heat accumulator, in a second step the explosive and / or propellant charge is poured into the casting mold and in a third step the mold is cooled in at least two further temperature steps.

Advantageous developments of the invention are characterized in the subclaims.

Claim 2 describes an advantageous and economically feasible insulation cover.

For technical reasons, a device according to claim 3 proves to be particularly favorable in practice.

The heat capacity of an insulation sleeve can be significantly expanded and predetermined by a cavity for receiving a heat transfer medium. The insulation sleeve can also be designed completely as a cavity and can be partially or completely filled with a heat transfer medium.

In order to achieve an optimal cooling process for the load, a heat transfer medium has proven to be favorable.

A heat transfer medium according to claim 6 is in place of liquid cargo to the outside until the areas of the cargo that are vulnerable to blow holes on the lower cross-sectional levels have solidified.

It is particularly advantageous to use the charge melt (see claim 7) as a heat carrier, in particular for reasons of simplified manipulation.

An embodiment according to claim 8 results in communicating vessels and thus brings about a particularly simple reflow of the solidifying melt into the casting mold. In the simplest case, the pouring opening of the mold represents the connecting line.

A casting method according to claim 9 or 10 has proven particularly useful.

• Fig. 1 ein Geschoss mit aufgesetzter Isolationshaube in Schnittdarstellung während des Erstarrungsprozesses der Ladung und
• Fig. 2 den oberen Teil eines weiteren Geschosses mit einer Wärmeisolation sowie einer eingezeichneten Isochronenschar.

Exemplary embodiments of the invention are described in more detail below with the aid of schematic drawings. Show it

• Fig. 1 shows a floor with an attached insulation hood in a sectional view during the solidification process of the load and
• Fig. 2 shows the upper part of a further floor with thermal insulation and a drawn isochronous family.

Parts that act in the same way are provided with the same reference symbols in both drawings.

1, a pouring funnel 2 is placed on a casting 1. A jacket 5 made of poly is in a collar 4 made of polyvinyl chloride, which is positively attached to the casting 1 urethane foam used with a cavity 11. The pouring funnel 2 is filled with melt to a level N in the usual way. During the solidification process, the melt can easily flow into the cargo space 6 through the relatively small pouring opening 6a, without forming voids. Here, a collar-shaped configuration of the pouring funnel 2 serves as a latent heat store 7, in which the melt solidifies from the outside inwards and thereby releases the latently stored heat energy to the outside, whereby in the area of the pouring opening 6a heat flow to the outside is delayed until the end, so that the melt solidified in this area of cargo last.

The insulation hood 9 (insulation sleeve) formed from the collar 4 and the jacket 5 is provided with a cover 10 in order to avoid radiation losses.

After solidification, the entire insulation hood 9 together with the so-called lost head 8 can be easily removed by turning it manually.

The insulation hood 9 has a progressively increasing insulation; the cooling rate can be influenced by selecting the ambient temperature; the spatial solidification process in Giessling 1 is largely independent of this.

• Anteil an Festkörpern, welche als solche keine Latentwärme abzugeben vermögen, der Wärmeleitwert des erstarrten Spreng-stoffes, die Erstarrungswärme des flüssigen Sprengstoffes und die Dichte des erstarrten Sprengstoffes.

To dimension the insulation hood 9 or its thermal insulation on a certain horizontal cross-section, the following physical data must be known about the explosives (or the propellant charge):

• Percentage of solids which as such are unable to give off latent heat, the thermal conductivity of the solidified explosive substance, the heat of solidification of the liquid explosive and the density of the solidified explosive.

• Dessen Wärmeleitwert sowie die inneren und äusseren Radien auf der jeweils zu berechnenden Querschnittsebene.

The Giessling must also know:

• Its thermal conductivity as well as the inner and outer radii on the respective cross-sectional plane to be calculated.

In addition, also in the respective cross section, the thermal conductivity of the intended insulating material, the inner and outer radii and the heat transfer coefficient of the outer surface of the insulation hood 9 to the air must be known from the thermal insulation.

• wobei ΔT die Temperaturdifferenz zwischen Sprengstofferstarrungszone und Aussenraum,
• dt die zur Abkühlung der erstarrten Sprengstoffmasse erforderliche Zeit und
• R der thermische Widerstand zwischen Sprengstofferstarrungszone und äusserer Oberfläche sind.

For the actual calculation, the system requirements are that, firstly, the heat released during the solidification of the explosive heat quantity dQ _L should be equal, as given by the heat conduction to the air heat quantity dQ _V:

• where ΔT is the temperature difference between the explosive solidification zone and the outside space,
• dt the time required to cool the solidified explosive mass and
• R are the thermal resistance between the explosive solidification zone and the outer surface.

In contrast to that in FIG. 1, the casting 1 FIG. 2 has a larger pouring opening 6a, so that no latent heat store is required. Nevertheless, the Represent the solidification process as a result of the insulation hood 9 in a generally characteristic manner. The drawn in isochronous family 3, drawn in at hourly intervals, clearly shows how the solidification area progresses from bottom to top and the melt in the area of the pouring opening 6a is still liquid after more than 6 hours in a central concentric area and thus results in a high-quality blow-free blasting operation.

At the edge, the horizontal planes A - H are designated, which served the previously considered calculation of the insulation hood 9.

In the present case, the calculation was based on a melt of pure trinitrotoluene (TNT) with a 20% solids content. The solids did not melt again; the result was a fine crystalline cast structure.

The insulation hood 9 was heated to the melting temperature of the TNT (approx. 80 °) for two hours, then the melt was poured into the pouring funnel 2 and then in two temperature steps, namely for two hours at a temperature of 70 ° to 80 ° C and then cooled to this at room temperature.

The devices and methods according to the invention are in no way limited to the use of TNT; any mixed explosives known per se which has solids in its liquid phase can be used for this. The solid component can also be introduced by another high-performance explosive, such as octogen, hexogen, penta, etc. The same also applies to the propellant charges known per se.

Claims (10)

1. Device for producing void-free explosives and / or propellant charges of predetermined spatial shape and composition by casting, the solidification process within the melt being progressively delayed from bottom to top, characterized in that an insulation sleeve (9) is provided outside the casting mold, whose radial heat transmission in any horizontal plane (BH) corresponds at least approximately to the radially flowing amount of heat released in the cross section in the same horizontal plane when the melt solidifies. (Fig. 2) 2. Device according to claim 1, characterized in that the insulation sleeve (9) consists of at least one plastic. (Fig. 1) 3. Device according to claim 2, characterized in that the insulation sleeve (9) consists at least partially of polypropylene and / or foamed polyurethane. (Fig. 1) 4. Device according to one of claims 1 to 3, characterized in that the insulation sleeve (9) has at least one cavity (11) for receiving a heat transfer medium. (Fig. 1) 5. The device according to claim 4, characterized in that the heat transfer medium has the same or a higher thermal capacity than the melt. (Fig. 1) 6. The device according to claim 4, characterized in that the heat transfer medium is a latent heat-storing medium. (Fig. 1) 7. The device according to claim 6, characterized in that the heat transfer medium is melt. (Fig. 1) 8. The device according to claim 7, characterized in that a connecting line between the melt located in the casting mold and the melt located in the cavity (11) is provided. (Fig. 1) 9. A method for producing void-free explosives and / or propellant charges with a device according to one of claims 1 to 8, characterized in that the insulation sleeve together with the heat transfer medium is heated in a first step for at least one hour to at least the melting temperature of the heat accumulator that in a second step the explosive and / or propellant charge is poured into the mold and that in a third step the mold is cooled in at least two temperature steps. 10. The method according to claim 8, characterized in that the mold is cooled for at least two hours at a temperature of 70-80 ° C and then at 20 ^* C.

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