Improvements in Cartridge Cases for Explosives.
Year: 1899

page_text: Date of Application, 20th Dec., 1899-Accepted, 3rd Feb., 1900
COMPLETE SPECIFICATION.
Improvements in Cartridge Cases for Explosives.
We, CHARLES HERBERT CURTIS, of 3, Gracechurch Street, in the City of London,
Explosive Manufacturer, and CURTIS'S & HARVEY LIMITED, of the same address,
Explosive Manufacturers, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
Hitherto cartridge cases, particularly for use with blasting powders, have, if
made of metal, been manufactured with one end closed, and when the explosive
has been filled into the cartridge case the other end has been closed either by
putting on a screw cap and making the joint tight with wax or other convenient
waterproofing substance, or when either metal or paper cases have been employed,
a wad has been used, and the edges turned over on to the wad, and the end dipped
in wax or other like waterproofing substance.
These methods have had several drawbacks. In the case of a metal cartridge
case the cartridge case before it was filled took up a great deal of space, on account
of its being extended, and the method of closing and afterwards making a tight
joint was troublesome and expensive and not always effective, and always liable
by the breaking of the waterproof substance to the joint becoming defective.
Our invention relates to a novel method of constructing and closing the ends
of a cartridge case. By our method the cartridge case is a tube made of soft
metal, paper or other suitable material and, particularly when made of soft metal,
can before being filled be packed and delivered in a flat condition. When the
cartridge case is to be filled the tube is opened by means of what is known as a
"former." At one end of the cartridge case we place a circular cup with its
edges bent upwards, the edge of the tube forming the cartridge case preferably
extending slightly beyond the edge of the cup. We place this cup supported by
the former inside the cartridge case against a turning over machine of the kind
ordinarily used for closing sporting cartridges. The protruding edge of the tube
thereupon folds or rolls over the edge of the cup so forming a new edge and then
the edge thus formed is again turned or rolled over upon itself and completes the
end of the cartridge in an inexpensive and easy manner. It is necessary that the
upstanding edge of the cup should be of such depth that in the completed joint
it shall be turned back upon itself and serve to clench the engagement of the tube
edge with the cup edge. In this way the edge of the tube becomes inseparably
engaged with the edge of the cup and the convolutions of the joint are pressed
together with such force by the turning over machine that the joint becomes
perfectly firm and rigid. The cartridge is then filled with the explosive and the
other end is closed in similar manner, the contents of the cartridge affording
sufficient support to the tube and cup when the cartridge case is pressed against
the turning over machine. The method of folding the edge has the advantage
of making the ends of the cartridge firm and rigid without the necessity of having
the cup or cover of thick material.
The tubes and cups can be made either of soft metal, such as thin steel, lead, or

page_text: paper, or other suitable material or one can be metal and one paper or such other
suitable material.
To make our invention more readily understood we refer to the accompanying
drawings in which a is the tube expanded to receive the explosive, and b, b, are
the cups which are shewn in Figure 1 in position for turning over. Fig. 2
shows the first turn or fold of the tube over the cup and Figure 3 shows the com-
pleted end, the cup being enlarged to show the convolutions of the joint more
clearly.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is:-
A cartridge case constructed as herein before described and having its ends
closed by a joint formed substantially as described and shown.
Dated this 20th day of December 1899.
THEO. MCKENNA,
17 & 18, Basinghall Street, London, E.C., Applicants' Agent.