IMPROVEMENTS IN THE CONSTRUCTION OF GUNS, HYDRAULIC CYLINDERS, AND OTHER LIKE HOLLOW BODIES SUBJECTED TO INTERNAL PRESSURE
Year: 1879

page_text: PROVISIONAL SPECIFICATION left by Charles Max Sombart at the Office
of the Commissioners of Patents on the 28th January 1879. A communica-
tion from Edward Buss, of Magdeburg, in the Empire of Germany.
CHARLES MAX SOMBART, of the Firm of Buss, Sombart, and Company, Engi-
neers and Patent Agents, of Magdeburg and Berlin, both in the Empire of Germany.
"IMPROVEMENTS IN THE CONSTRUCTION OF GUNS, HYDRAULIC CYLINDERS, AND
OTHER LIKE HOLLOW BODIES SUBJECTED TO INTERNAL PRESSURE." A commu-
nication from Edward Buss, of Magdeburg aforesaid.
This Invention relates to improvements in the construction of vessels or chambers
which are required to resist a high degree of internal pressure or bursting strain,
such, for example, as hydraulic cylinders, guns, and the like.
It has been ascertained in the case of vessels or chambers having sides or walls of
considerable thickness, and exposed to a high degree of internal pressure, that the
different parts of the walls are very unequally affected by the strain from the
interior to the exterior, the internal parts being exposed to the greatest, and the
external parts to the least amount of strain, so that the thickness of the wall
requires to be increased in a greater ratio to enable them to withstand a propor-
tional increase in the strain, and from a certain maximum limit of pressure a
further increase in the thickness of the walls ceases to add to the strength of the
vessel or chamber.
According to this Invention the walls of cylindrical chambers, for example, are
constructed of a certain number of separate thicknesses of material, which are not,
however, arranged to fit tightly one over the other by being shrunk on or by other
known methods so as to be in a state of initial tension of varying degrees, according
to the distance of the several layers from the interior, as is the case more particu-
larly with regard to guns as ordinarily constructed, but are arranged loosely one
within the other, the opposing or bearing surfaces of each of the said thicknesses
being in the form. of a series of frustums of cones, the angle or taper of which is
made to vary in a certain proportion from the inner to the outer series. The
pressure on the closed end of the chamber in the direction of the axis of the cones
causes the frustums to move in this direction, wedging them one into the other,
I Prine Adl

page_text: thereby considerably increasing the expansion of the material of which they are
composed, which is insufficient as regards the external part in the case of vessels or
-chambers-constructed_with_solid walls, and enabling them to withstand a much
greater amount of internal pressure in proportion to their thickness.
In carrying out this Invention as applied to the construction of hydraulic
cylinders, for example, according to one modification the thicknesses forming the
sides of the cylinder-are-cast-one within the other by casting the external thickness
first and the internal thickness last. The opposing or bearing surfaces of each-of-
the said thicknesses are composed-of-a-series_of_hollow frustums of cones arranged
in the form of steps, and fitting loosely one within the other. The conical surfaces-
thus formed are forced against one another by the internal pressure only, and the
force thus exerted upon the said surfaces is transmitted radially through and
expands all the thicknesses in succession from the interior to the exterior.
According to other modifications the space between the conical surfaces is filled
up with any suitable material, and the series of frustums on each thickness is in
some cases replaced by a uniform conical surface generated by a curve of suitable
form, for which however straight lines approximating to the same angles may be
substituted.
In carrying out this Invention as applied to the construction of guns the gun is
composed of several thicknesses provided with conical surfaces as herein before
described.
In lieu of simple frustums of cones spiral conical surfaces may be employed, and
in this case the different thicknesses of which the walls are composed may be
screwed into their relative position; this arrangement, as well as that in which the
uniform conical surface is employed as hereinbefore referred to, admits of a suitable
manipulation or preparation of the opposing or bearing surfaces,
The external thickness may be prevented from moving in the direction of its
axis whilst the internal thicknesses are allowed to move in this direction, so as to
force their conical surfaces against each other, or the converse of this arrangement
may be adopted, but in this latter case the closed end of the chamber formed by
the cylinder or gun should form part of the external thickness, and be made with a
flange so as to work close against the internal thickness. The conical surfaces
should also be inverted (with the apices of the cones in the opposite direction to
the first arrangement with regard to the closed end of the chamber), so that the
pressure on the closed end of the chamber may cause the conical surfaces on the
external thickness to be forced against those upon the adjacent thickness, and so
transmit the strain to the other thicknesses in succession from the exterior to the
interior.
In many cases, as for example, in the case of guns in which the internal pressure
is suddenly generated, and the expansion of the different thicknesses of which the
walls of the chamber are composed cannot be communicated with sufficient rapidity
from one to the other, or-when it is desired to avoid any motion of the different
thicknesses upon one another the said thicknesses may be forced-together-at-the
maximum pressure to which they are liable to be exposed, and secured in that
position by wedges or other suitable means before being used.
The expansion of cach thickness is rendered uniform, and the thickness of the
walls is enabled to be in exact proportion to the internal pressure by employing a
suitable number of thicknesses, and forming the series of conical surfaces of a
certain taper or angle increasing in proportion from the interior to the exterior.
In the case of chambers so constructed, provided that homogeneous material is
employed, and under the condition that the internal pressure in proportion to the
area of surface is equal to the expansion allowed the thickness required for the walls
will be equal to the radius of the interior, and if the pressure is doubled it must be
equal to twice the said radius and so on. When a less number of thicknesses are
employed a more or less similar result will be obtained according to the number
employed.

page_text: The artificial expansion of the material herein-before referred to produced by
shrinking on the various thicknesses or other known methods of manufacturing
thick walls for chambers exposed to high degrees of internal pressure is very
uncertain and irregular, whereas by means of this Invention the same can be effected
with accuracy and precision.