Title of Invention

"A PROCESS OF PREPARATION OF COMBUSTIBLE CARTRIDGE CASES"

Abstract

1) A process for the preparation of combustible cartridge case comprising in the step of : a) subjecting a mixture of cellulose sheets in water to the step of beating, b) adding copper naphthenate solution to said mixture during the step of beating, c) adding   57   -   63%   of  nitrocellulose,   5.5-6.5%   of dibutylphthalate, 17-21% of nitroguanidine, such as picrite, 0.9-1.1% of diphenylamine to the mixture/pulp to form a slurry, d) diluting said slurry with picrite water to obtain reduction of homogenous slurry consistency, e) allowing said slurry to stand under constant agitation, f) pumping of said slurry to a felting machine wherein performs of combustible components are felted on the mandrel, g) removing excess water from the felted perform, h) drying of performs, i)  gelatinizing dried combustible components with acetone, j) pressing gelatinized combustible components into pressing mould and subjecting said components to step of compression, k) drying of said components, L) coating said components with shellac varnish.

Full Text

This invention relates to the preparation of combustible cartridge cases. Such combustible cartridge cases are used in the tank/artillery gun ammunition. The function of a cartridge case of ammunition is to hold propellant charge, primer, projectile, and provide a means of rearwards obturation during firing cycle. Brass is the material which is most commonly used in the manufacture of cartridge cases. It provides for most purposes the ideal combination of strength, hardness, elasticity and resistance to corrosion. Although the use of brass is almost universal, other materials such as steel, aluminium and plastic are also used with limited success. Fully combustible cartridge cases and semi combustible cartridge cases are known in the art as these offer specific advantages over conventional brass cases. When semi combustible cartridge cases ammunition is fired form the gun, the combustible parts burns completely alongwith the propellant charge and it imparts energy to the projectile. They reduce both fumes and heat in the crew compartment. Combustible cartridge cases also weigh less than their metal counterparts. Various compositions based on nitrocellulose cellulose, diphenylamine and resins have been suggested in various publications. In such publications, the percentage of NC and its nitrogen contents and the nature of resins/binders and its percentage in the formulation are different. Such publications also cover two different processes for the manufacture of combustible cartridge cases, namely (i) the felting or moulding process and (2) paper making process for paper winding process. Each process has its own advantage/disadvantages. The felting process has an advantage over paper making process for manufacturing complex shape of cccs., whereas paper making process is very successful for making at a high production rate and at low cost than felting process. An object of the present invention is to propose an improved process of the preparation of combustible cartridge cases which are used in the tank/ artillery gun ammunition. Another object of the present invention is to propose a process of preparation of combustible cartridge cases which weigh less then their metal counterparts. Yet another object of the present invention is propose a process of preparation of combustible cartridge cases with gas generating compound without .any resins or binders. Yet another object of the present invention is to propose a composition for combustible cartridge cases with gas generating compound wherein the said gas generating compound improves the life of the gun. Further object of the present invention is to propose a composition for combustible cartridge cases wherein said gas generating compound provides better combustibility. A still further object of the present invention is to propose a combustible cartridge case wherein the process of preparation is carried out at much lower temperature. According to this invention there is provided a process for the perparation of combustible cartridge/ case comprising in the step of : a) subjecting a mixture of cellulose sheets in water to the step of beating, b) adding copper naphthenate solution to said mixture during the step of beating, c) adding 57 - 63% of nitrocellulose, 5.5-6.5% of dibutylphthalate, 17-21% of nitroguanidine, such as picrite, 0.9-1.1% of diphenylamine to the mixture/pulp to form a slurry, d) diluting said slurry with picrite water to obtain reduction of homogenous slurry consistency, e) allowing said slurry to stand under constant agitation, f) pumping of said slurry to a felting machine wherein performs of combustible components are felted on the mandrel, g) removing excess water from the felted perform, h) drying of perform, i) gelatinizing dried combustible components with acetone, j) pressing gelatinized- combustible components into pressing mould and subjecting said components to step of compression, k) drying of said components; 1) coating said components with shellac varnish. This invention relates to the formulation of combustible cartridge cases with gas generating compound (picrite) and without any resins or binders as known from the prior art. This gas generating material improves the life of gun as it imparts a cooling effect to gun. Picrite also helps to provide better combustibility of combustible cartridge case. Use of gas generator is a distinct feature of the formulation/ making this invention unique in its kind and having an advantage over all other compositions known in the art. This composition is suitable for all types of tank/artillery gun ammunition operating at a pressure of 1500 bar to 6000 bar and comprising of single base, double base, tripple base and high energy propellents. A special feature is, application of a special type of shellac varnish coatinq to co'mbustible cartridge case for moisture proof and to prevent cook off. The combustible cartridge cases are prepared from 57-63% by weight nitrocellulose, 17-21% nitroguanidine (picrite), 12-16% -cellulose, 5.5-6.5% dibutylphthalate, / 0.9-1.1% diphenylamine and in traces additive' such as copper naphthenate. NC and nitroguanidine provide complete combustibility to the cartridge case and . -cellulose provides structural integrity. The cases are made waterproof by coating with shellac varnish. The combustible cartridge case made from this such a composition have compatibility with single base/ double base/ tripple base and high energy propellants. The characteristics of combustible cartridge cases made from this composition are shown in Table 1. TABLE 1 (Table Removed) The present process concept employed in making combustible bodies/ caps/ spacers and sleeves of three dimensional shapes formulation as mentioned above. The process consists in the following steps and as schematically shown in Fig.l of the accompanying drawing. We claim; 1) A process for the preparation of combustible cartridge case comprising in the step of : a) subjecting a mixture of cellulose sheets in water to the step of beating, b) adding copper naphthenate solution to said mixture during the step of beating, c) adding 57 - 63% of nitrocellulose, 5.5-6.5% of dibutylphthalate, 17-21% of nitroguanidine, such as picrite, 0.9-1.1% of diphenylamine to the mixture/pulp to form a slurry, d) diluting said slurry with picrite water to obtain reduction of homogenous slurry consistency, e) allowing said slurry to stand under constant agitation, f) pumping of said slurry to a felting machine wherein performs of combustible components are felted on the mandrel, g) removing excess water from the felted perform, h) drying of performs, i) gelatinizing dried combustible components with acetone, j) pressing gelatinized combustible components into pressing mould and subjecting said components to step of compression, k) drying of said components, L) coating said components with shellac varnish. 2) A process as claimed in claim 1 wherein said step (d) of dilution of said slurry with picrite water is carried out till the homogeneous slurry consistency reduces to approx 0.5-2% soild. 3) A process as claimed in claim 1 wherein said slurry is allowed to stand under constant agitation for a minimum of 1 hour. 4) A process a claimed in claim 1 wherein the mendrel is connected to a vacuum source to provide vacuum in the range of 650-700mm of kg. 5) A process a claimed in claim 1 wherein excess water is removed by pneumatic rubber balloon inflated at a pressure of about 2- 5kg/cm2. 6) A process a claimed in claim 1 wherein the step of drying of performs is carried out at a temperature of 55-65°c for 3-6 hours. 7) A process a claimed in claim 1 wherein the step of gelatinization is carried out at room temperature. 8) A process a claimed in claim 1 wherein gelatinized combustible components are inserted in to pressing mould and compressed by means of hydraulic rubber balloons. 9) A process a claimed in claim 1 wherein the step of drying of gelatinized and processed combustible components are dried at temperature of 45-55°c for 3-4 hours. 10) A process for the preparation of combustible cartridge cases substantially as herein described

Documents:

67-del-1995-abstract.pdf

67-del-1995-claims.pdf

67-del-1995-complete specification (granted).pdf

67-del-1995-correspondence-others.pdf

67-del-1995-correspondence-po.pdf

67-del-1995-description (complete).pdf

67-del-1995-drawings.pdf

67-del-1995-form-1.pdf

67-del-1995-form-19.pdf

67-del-1995-form-2.pdf

67-del-1995-form-3.pdf

67-del-1995-gpa.pdf