GB1585083A - Method of treatment of cast high explosives - Google Patents

Description

(54) METHOD OF TREATMENT OF CAST HIGH EXPLOSIVES We, MEssFRscHMlTT-BoLKow-BLoHM GESELLSCHAFT MIT BESCHRANKTER HAFTUNG, of 8000 Munchen, German Federal Republic, a company organised and existing under the laws of the German Federal Republic do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:: This invention relates to a method treating cast high explosive substances which are prepared from a high proportion of at least one unmelted (solid) high explosive substance, particularly hexogen, in various grain sizes, and a smaller proportion of at least one melted explosive substance, particularly TNT, both explosive substances being heated and suspended and then poured into a mould, which may be an actual warhead casing. The solid explosive constituent can be compressed in the mould and the suspension subjected to pressure, after which the solid and the melted explosive constituent are cooled off to room temperature preferably in stages.

Reference is made to co-pending Application 4433/76 (Serial No.1585082).

According to this invention there is provided a method of treating cast high explosives which have been prepared from a high proportion of at least one unmelted (solid) high explosive substance in various grain sizes, and a smaller proportion of at least one melted explosive substance both explosive constituents being heated and suspended and then immediately poured into a mould, which may be a warhead casing, after which the solid and the melted explosive constituent are cooled to room temperature, preferably in a number of stages, in which method the explosive mass, after the melt has solidified, that is after it has partly or completely cooled to room temperature, is re-heated to a temperature just above to the melting point of the explosive constituent melted in the production stage, the temperature being maintained for a time, after which the explosive mass is re-cooled to room temperature slowly to prevent cracking.

After solidification of the melt, therefore, the treatment of the explosive mass can be carried out either while the cooling process is in progress, so that the method of treatment according to the invention is integrated into the entire production process, or treatment may be effected after the moulded body has cooled down to room temperature, constituting an after-treatment. By after-treatment is meant that the treatment immediately follows the cooling but a complete warhead with charge can nevertheless undergo an after-treatment of this kind some considerable time after assembly, possibly even some years later and also repeatedly.

The following operations and times for the (after-) treatment according to the invention have been found preferable in the case of a 100 mm calibre warhead with a charge of hexagen and TNT. The explosive mass is heated from room temperature to 81 to 900 C, particularly to 850C with this heating period being 2 to 4 hours, particularly 3 hours; the constant after-treatment temperature is maintained for 0 to 1 hours, particularly lihour, the cooling period being 12 to 14 hours, particularly 13 hours, and the cooling can be carried out in stages and the temperature of 750C maintained for a certain period when reached, during which period the melt fully solidifies. This avoids stresses in the body of the charge.

This method of treatment ensures that the permissible heating temperature and the permissible time at this temperature which enables the maximum possible crystallization point to be obtained in the subsequent cooling of the melt can be maintained, that is the melt only needs to be liquified, immediately following which it can be slowly re-cooled.

The method of the invention can be applied in such a way that the explosive mass is melted a number of times in succession and as tests have shown in this the crystallization point is raised a few degrees centigrade each time. This is useful where, as a result of particularly unfavourable circumstances, the crystallization point has been very low at the actual production stage and has led to a very unfavourable finely crystalline structure.

The invention provides a means of subsequently increasing the crystallization point of an explosive melt as required, in order to obtain the desired structure with the necessary properties for the charge. The elongated TNT crystals sought are intrinsically, and by reason of their firm adhesion to the adjacent hexogen grains, insensitive to the formation of further craks. The deliberate very slow cooling also enables internal stresses in the explosive moulded body to be avoided altogether.

Furthermore the method of treatment of the invention ensures that the explosive constituent to be melted will be more evenly distributed within the charge, so that homogeneity is once again increased. This improves the efficiency of the charge, owing to the evenness of the detonation wave front and the satisfactory formation of an armour piercing spike from a liner of a hollow charge. The mechanical strength of the charge is also increased by about 10%.

Octogen can be used in place of hexogen and trinitro-benzene in place of TNT.

WHAT WE CLAIM IS: 1. A method of treating cast high explosives which are prepared from a high proportion of at least one unmelted (solid) high explosive substance in various grain sizes and a smaller proportion of at least one melted explosive substance, both explosive constituents being heated and suspended and then immediately poured into a mould which may be a warhead casing, after which the solid and the melted explosive constituent are cooled to room temperature,preferably in a number of stages, in which method the explosive mass, after the melt has solidified, that is after it has partly or completely cooled to room temperature, is re-heated to a temperature just above the melting point of the explosive constituent melted in the production stage, the temperature being maintained for a time after which the explosive mass is re-cooled to room temperature slowly to avoid cracking.

2. A method in accordance with claim 1, wherein the explosive body comprises hexogen and TNT and is re-heRted from room temperature to 81 to 90 C, preferably to 850C, the heating period being 2 to 4 hours, preferably 3 hours, the constant after-treatment temperature being maintained for 0 to 1 hour, preferably 1E hour, while the period of cooling to room temperature amounts to 12 to 14 hours preferably 13 hours, the cooling being effected preferably in stages.

3. A method according to claim 1 comprising repeated applications of the treatment steps set forth in the preceding claims.

4. A method in accordance with claim 1 or 2 or 3, carried out substantially as herein described.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. subsequently increasing the crystallization point of an explosive melt as required, in order to obtain the desired structure with the necessary properties for the charge. The elongated TNT crystals sought are intrinsically, and by reason of their firm adhesion to the adjacent hexogen grains, insensitive to the formation of further craks. The deliberate very slow cooling also enables internal stresses in the explosive moulded body to be avoided altogether. Furthermore the method of treatment of the invention ensures that the explosive constituent to be melted will be more evenly distributed within the charge, so that homogeneity is once again increased. This improves the efficiency of the charge, owing to the evenness of the detonation wave front and the satisfactory formation of an armour piercing spike from a liner of a hollow charge. The mechanical strength of the charge is also increased by about 10%. Octogen can be used in place of hexogen and trinitro-benzene in place of TNT. WHAT WE CLAIM IS:

1. A method of treating cast high explosives which are prepared from a high proportion of at least one unmelted (solid) high explosive substance in various grain sizes and a smaller proportion of at least one melted explosive substance, both explosive constituents being heated and suspended and then immediately poured into a mould which may be a warhead casing, after which the solid and the melted explosive constituent are cooled to room temperature,preferably in a number of stages, in which method the explosive mass, after the melt has solidified, that is after it has partly or completely cooled to room temperature, is re-heated to a temperature just above the melting point of the explosive constituent melted in the production stage, the temperature being maintained for a time after which the explosive mass is re-cooled to room temperature slowly to avoid cracking.

2. A method in accordance with claim 1, wherein the explosive body comprises hexogen and TNT and is re-heRted from room temperature to 81 to 90 C, preferably to 850C, the heating period being 2 to 4 hours, preferably 3 hours, the constant after-treatment temperature being maintained for 0 to 1 hour, preferably 1E hour, while the period of cooling to room temperature amounts to 12 to 14 hours preferably 13 hours, the cooling being effected preferably in stages.

3. A method according to claim 1 comprising repeated applications of the treatment steps set forth in the preceding claims.

4. A method in accordance with claim 1 or 2 or 3, carried out substantially as herein described.