Plastic and nonmetallic article shaping or treating: processes – Explosive or propellant article shaping or treating – Extrusion to form sheet or rod
Patent
1991-01-07
1993-11-30
Nelson, Peter A.
Plastic and nonmetallic article shaping or treating: processes
Explosive or propellant article shaping or treating
Extrusion to form sheet or rod
264 34, 264 35, 149 198, 149 1992, 149 1993, 1491096, C06B 2100, C06B 4100
Patent
active
052662420
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method of making a tribasic propellant charge powder of nitrocellulose, blasting or explosive oil, and a third crystalline energy carrier, as well as additives, making use of a solvent. The invention also relates to an apparatus for carrying out that method.
The tribasic propellant charge powders are known also as "cold" powders. They have the advantage of better barrel protection, i.e. prevention of erosion than the conventional "hot" powders which do not contain a third crystalline energy carrier.
In making propellant charge powders with an explosive oil, this explosive oil acts as a gelatinizing agent for the nitrocellulose. In the case of tribasic propellant charge powders the quantity of blasting oil often is not sufficient for the complete gelatinizing of the nitrocellulose and for uniform and homogeneous binding of the third crystalline energy carrier in the powder mixture, particulary if the crystalline energy carrier is present in great proportion. In that event tribasic propellant charge powders are prepared with the use of an organic solvent as a gelatinizing aid. The solvent, such as a mixture of acetone and alcohol is added while the pulverous raw stock is being mixed and is withdrawn in the end from the finished powder.
The usual procedure is to produce tribasic propellant charge powders in batches. All the components of the powder, with the solvent being added, are mixed into a powder mass, which is moist with solvent, and kneaded in a closed kneader until the powder mass is homogenized and gelatinized. The gelatinized powder mass is compressed in a pot-type press to yield powder strands which subsequently are cut to length and from which the solvent is removed by drying. This procedure is very labor-intensive as the powder mixture requires a lot of manual treatment.
Likewise known is a method which can be operated continuously to produce tribasic propellant charge powders with solvents (German patent 24 61 646 and U.S. Pat. No. 4,051,207). With this procedure a mixture, moist with solvent, of all the components of the propellant charge powder is preplasticized in an open, continuously operating kneader, i.e. it is partly gelatinized. As a rule, the substance passes the kneader several times. Subsequently the preplasticized substance containing solvent is subjected to final gelatinizing in an extruder and converted into granular consistency. As a rule, the extruder, too, is to be passed several times. Thereupon the granular material is compressed in another extruder to yield the desired powder strands which still have to be cut to length and dried. This process is highly expensive in respect of the mechanical equipment needed and the process control which must be carried out in adjusting and monitoring process parameters.
It is an object of the invention to indicate an improved process of the kind defined initially adapted for continuous operation and to be realized with less mechanical expenditure than before, the operating cycle being easily adjustable and controllable. It is another object of the invention to provide an apparatus suitable for carrying out the process in question.
Starting from the process of the kind mentioned initially, the problem is solved in accordance with the invention in that raw stock moist with water and premixed of nitrocellulose moist with water and a blasting oil is gelatinized in a continuously operating open kneader, being dried at the same time, the kneading process being adjusted such that the raw stock upon leaving the kneading apparatus has been converted into a fully gelatinized intermediate product having a residual water content of less than 3%. When leaving the kneading apparatus the intermediate product is granulated, the granulated intermediate product (granular material) and the third crystalline energy carrier as well as the solvent are supplied to a continuously operating closed extruder in which they are homogenized by kneading and from which they are extruded as powder strands which are moist with solvent. These powd
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Miehling Wolfgang
Mogendorf Klaus-Dieter
Nelson Peter A.
WNC-Nitrochemie GmbH
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