Improvements in the Production of Rims of Cartridge Cases.
Year: 1895

page_text: Date of Application, 2nd Nov., 1895-Accepted, 7th Dec., 1895
COMPLETE SPECIFICATION.
Improvements in the Production of Rims of Cartridge Cases.
I, FREDERIK MOHR, of 42 Schönbeckerstrasse Magdeburg, Germany, Engineer,
do hereby declare the nature of this inveution and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement :-
The formation of an external rim or thickening on cartridge cases was heretofore
mostly effected by pressing the necessary material for forming such rim out of the
base of the case, or by forming the base with an inward arched curvature, and,
after cutting an external groove round the cylindrical part near the base,
flattening the latter out, so as to make the periphery thereof below the groove
project.
In the first named case, a very considerable amount of power is required and
the operation can only be performed slowly, while in the latter case only a
comparatively small rim can be formed, and in addition there is a loss of material
in cutting the circular groove.
According to my present invention the requisite material for forming the rim is
not obtained from the base, but from the side walls of the cartridge case, being
forced from the latter into the required position flush with the base by one or more
upsetting and pressing operations, the number of such operations depending upon
the form or thickness of the rim.
The accompanying drawing shews the mode of carrying out the invention with
two pressing operations.
Fig. 1 shews a section of the cartridge base having the requisite form imparted
to it for enabling the invention to be carried out thereon, such form being imparted
by any known processes of drawing rolling and stamping.
The base a is for this purpose preferably formed with a more or less outward
arched bulge, but it can also be formed flat."
Immediately above the base the side walls of the case are formed with an
internally projecting thickening b. In the side walls thus thickened is contained
the material required to form the projecting rim. The form of the tools required
for this purpose is shewn at Figs. 2 and 4.
The pressing die o is flat; the inner die u is formed with a rounded edge
orresponding to the form of the point of junction of the side walls of the case
with the base. The matrix s has a circular grooves' for the reception of the
material coming from the thickened part of the side walls. During the pressing
operation, the cartridge case rests with its internal projection b upon the rounded
edge of the inner die u. By the pressure of the outer die o the slightly bulged
base is pressed flat, and the thickened side is forced outwards so as to cause the
material contained therein, by upsetting and pressing, to fill the groove s¹ of the
matrix s.
By this operation the case receives the form indicated at Fig. 3, with
the outward projecting thickening or rim e. The process is then repeated with the
tools shewn at Fig. 4. The two discs o and u are formed in the same manner as
those for the first operation. The matrix & however has a differently formed
grooves, which has the exact form of the rim to be produced.
In this operation the cartridge case rests. with the external thickening e upon the
edge of the groove s².
On the descent of the die o, the thickening e is upset whereby it is made to fill
out the recess & and thus to form the rim d of the required configuration as shewn
at Fig. 5.
From the above description it will be seen that the stamping process need only

page_text: consist of a single operation if a rim having only a slight projection, such as e
Fig. 3 is required. It suffices in that case to subject the thickened part 6 of the
case to a single upsetting and pressing operation by means of the tools. shewn at
Fig. 2. When on the other hand the rin is required to project to a greater extent,
the operation is repeated as often as is necessary to convert the slightly projecting
rime into a rim having a greater projection. The pressing is then effected by the
use of several matrixes (s) with grooves (s) gradually approximating to the
form of the finished rim.
It is of advantage in this operation that only a moderate pressure need be
employed that the operations are simple, and that the tools are of easy and cheap
manufacture. It is also of advantage that the rim can be produced of any size
without loss of material, and that for each operation the same upper and lower
dies can be employed, only the matrixes requiring to be changed. Lastly, the
position of the fibres in the material forming, the rim is advantageous, and, with a
sufficiently rounded edge of the inner 'die, an internal strengthening of the
junction between the base and sides is effected.
In the process so far described the outer diameter of the case is the same in all
the operations, as indicated on the drawings by two parallel dotted liiies extending
along the Figs. 1 to 5.
Instead of carrying out the process in such manner that the outer diameter of
the case remains the same in all the operations, and that the thickened part b is
pressed radially outwards, the process can be carried out, as shewn at Figs. 6 and 7,
in such manner, that the thickened part 6 of the side walls of the case is not forced
outward but that the drawn part g of the side walls of the case is drawn to a
smaller diameter.
At Fig. 6 the inner diameter at the point of the thickened part of the side
of the preliminary formed cartridge case, is equal to the inner diameter Fig 7
of the finished case, while the outer diameter y' of the preliminary formed case-
is greater than the diameter of the finished case. The tools are for this purpose
so formed, that by means thereof the case with the diameter y¹ is brought to
the desired diameter y Fig. 7. They differ from those employed in the first
described process only in that the matrix is formed with a more gradually tapering
junction between the upper groove and the lower cylindrical part.
By this means the same effect is produced as in the first described process.
In both cases there is a relative radial displacement of the thicker and the thinner
drawn part of the side walls of the cartridge case.
Both modes of carrying out the process can of course be combined with each
other.
'
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. The process for the manufacture of cartridge cases wherein for the formation
of the rim, an internally projecting thickened part b of the side walls of the case.
is pressed between an internal and an external die and a matrix in such manner
that it is forced outwards by the inner die, into a groove of the matrix, substantially,
as described with reference to Figs. 1 to 5 of the drawings.
2. In the process referred to in the first claim the modified arrangement whereby
the inner thickening (b) is brought to the outside for forming the rim by reducing
the diameter of the thin drawn portion of the case walls by means of a matrix of
a smaller diameter, substantially as described with reference.to Figs. 6 and 7.
Dated this 2nd day of November 1895.
1 P