A METHOD AND AN APPARATUS FOR PROCESSING THIN WEB CASE BONDED COMPOSITE PROPELLANT GRAINS

摘要

The present invention relates to an apparatus and method for casting of composite propellant material/slurry to obtain thin web case bonded composite propellant grains having diameter in range of 200mm to 110mm with the composite propellant slurry having viscosity in the range of 12,000 poises to 30,000 poises by using pressure/bottom casing technique. Bottom casting set-up (as shown in fig.) comprises of a mass holder (3), a piston (2), a ball valve (6) at the bottom of mass holder followed by a manifold (5) with two outlets having ball valve (6) in each line. These valves are connected with flexible branded polythene hoses (7). These hoses are tightened on the nipples. Other ends of hoses are connected to the cones (8) of mould assembly fixture. Mandrels (12) are positioned at the centre of each mould (10) at the bottom and over the cone. Then paper sleeves (inhibition sleeves) (11) are inserted in the moulds which get fitted in the slot given on the bottom centering ring (9). The mandrels are then held at the top with a top centering ring (13). Finally the top is closed with a metallic cup (14) with provision on it for application of vacuum (15). For multiple grain casting manifold is provided with suitable no. of outlets. The propellant slurry is filled up in the mass holder under vacuum and then injected into the moulds under the pressure of the piston. The moulds are then pressurized at a predetermined pressure for a required time to consolidate the slurry and remove air voids. The consolidated slurry is then cured at a temperature in the range of 40°C to 70°C for 1 to 5 days. The cured grains are finally removed for the moulds as free grains and obtaining the paper insulated case bonded pyrogen igniter grains.