Societe Nationale Des Poudres Et Explosifs

Alain Brasquies

Michel B Maures

Hubert Delarche

This invention relates to combustible or semi-combustible cases intended in particular for artillery ammunition. More specifically, the invention relates to combustible cases bodies obtained by spirally winding combustible paper tapes containing nitrocellulose and having an improved mechanical resistance relative to previous combustible tape bodies, thanks to the fact that the combustible paper tapes form three distinct coaxial layers in terms of their density and structure. The case bodies according to the invention are obtained by spiral winding around a mandrel 80 a sheet 70 consisting of an uncalendered combustible paper tape 41 and six calendered combustible paper tapes 42-47 with density between 0.9 and 1.2 g/cm.sup.3, the tapes being pasted to each other according to a helical angle .alpha. such that the helical pitch P is larger than the width w1 of the tape 41 which thus forms a helix with turns which are not joined together. A calendered combustible paper tape 71 previously pasted with density lying between 1.15 g/cm.sup.3 and 1.3 g/cm.sup.3 is then spirally wound around the tube thus formed according to the a helical angle .beta. such that the turns of the helix formed by the said tape 71 overlap. The tube thus formed is then cut to the desired length of the case body.

Combustible or semi-combustible case bodies consisting of a large number

According to the invention the reels 10 of cellulose thread wound in a loose manner around a hollow perforated core are arranged on the nozzles 9 carried by the hollow arms 8 of a rotor 7a placed on a hollow frame 7 situated at the bottom of a tank 6. A pump 13 causes the nitrating medium 15 consisting of a mixture of nitric acid and methylene chloride to circulate into the pipe 14 from where it passes into the frame 7 and then to the rotor 7a from where it is brought under pressure via the pipes 8 and the nozzles 9 to the hollow perforated core of each reel. The nitrating medium then passes radially along the mass of thread making up each reel and returns to the pump 13 via the pipes 12. After nitration the nitrocellulose threads are immediately stabilized by washing them with water in a similar installation to that used for nitration. The process according to the invention makes it possible to manufacture reels of nitrocellulose thread of good quality in a simple manner in large quantities without the manufacturer having to perform delicate unwinding and reeling operations on the thread before and after nitration.

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Bergerac, France

Alain Brasquies