Improvements in and relating to the Manufacture of Metallic Hollow-ware.
Year: 1899

page_text: Date of Application, 19th Oct., 1899-Accepted, 2nd Dec., 1899
COMPLETE SPECIFICATION.
Improvements in and relating to the Manufacture of Metallic
Hollow-ware.
I, HEINRICH ALBERT ECKSTEIN, of Querstrasse 27, Leipzig, Germany, Merchant,
do hereby declare the nature of this invention and in what manner the same is
to be performed to be particularly described and ascertained in and by the
following statement:-
In the production of metallic hollow-ware from plates the method has hitherto
been to force the plates through dies by means of plungers exerting suitable
pressure upon the plates.
In this case the bearing surfaces of the plungers must be so large as to
overcome the resistance of the edges of the plates to the formation of side walls.
For a given size of plates one is therefore limited as regards the dimensions of
the hollow bodies to be formed.
Now according to this invention the process is reversed as the dies accomplish
the dishing of the plates whilst the mandrels are necessary only for determining
the bores and can therefore be of any desired diameters, and the hollow bodies
are formed by an equal forging pressure which is continuously exerted on the
edges of the plates or on the peripheries of the hollow bodies that are in process
of formation.
As will be seen from Figs. 1, 2, 3, and 4 of the accompanying drawings, this
pressure is given by means of two bipartite or multipartite dies a and b of
which one, b, is suitably fixed and supported, whilst the other, «, forms the
head of a suitable forging press, and whose diameter decreases continuously
from the entrance, like that of a funnel, to a place where the hollow body in
process of formation is bent over so that its inner annular surface begins to
touch the mandrel. During this first stage of the process the concentric cross-
sections of the plate are substantially thickened whilst in a radial direction
there occurs neither thickening nor drawing out.
Now to produce a hollow body of any desired length and thickness of annular
wall a lengthening of the wall is necessary as a second stage. But if this were
attempted by means of similarly tapering but prolonged dies there would
result, in consequence of the conical shape of the forging dies, a very con-
siderable pressure on the mandrel and therefore on the bottom of the hollow
body. The annular wall of the hollow body would therefore not be forged on
the mandrel but drawn substantially as in a draw ring. In this case consequently
the reduction of the wall would be limited by the strength of the bottom or
end or of the reduced annular wall. But if the cone were made very tapering
in order to reduce the pressure to be exerted by the mandrel to a minimum, the
die would be so long and the forging surface so large that even with the greatest
expenditure of energy it would be impossible to lengthen the side wall of the
hollow body.
In the second stage of the process according to this invention all these disadvan-
tages are obviated, as is shown in Figs. 1, 2, 3 and 4. In this case the reduction

page_text: of the wall is caused by simple forging by the succession of several straight
pairs of forging parts e f which are provided on the dies, and which decrease in
diameter to the desired dimension of the tube. As the apertures of the pairs
of the forging parts e f are co-axial, with the mandrel, there can of course be
no longitudinal pressure during the process of forging and the feeding of the
forged piece can be accomplished by hand as under an ordinary forging hammer.
Therefore, by means of this arrangement the reduction of a thick wall to the
thinnest tube-wall can be effected in one operation without any straining of the
bottom and the annular wall of the hollow body. The two operations consisting
of dishing the plate and lengthening the annular wall can also be carried out
separately.
In Fig. 1, there are shown by dotted lines successive forms, h, i which the
plate g assumes when the hollow body is in process of formation in the funnel
formed by the two dies a and b,. and the hollow body k itself when its internal
surface begins to bear on the mandrel 7. The counter-mandrel m serves for
centering the plate for dishing the same. Fig. 3 illustrates the step-by-step
forging of the tube wall by means of the multiple-hammer device of the dies
and Figs. 5 and 6 show the plate to be operated upon. Fig. 7 shows a square
plate which may, before the plate is put into the forging apparatus described,
be bent, by ordinary forging, into the form indicated in side elevation in Fig. 8,
to facilitate the proper centring of the plate at the commencement of dishing
in the said apparatus.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is:-
1. A process of forging metallic hollow-ware from flat plates wherein a plate (4)
to be operated upon, which is held concentrically by a feeding mandrel (/)
and a counter-mandrel (m), is converted into a hollow body by means of two
conical dies (a and b) having a funnel-shaped portion in which by a succession of
blows of one of the dies, which forms the head of a forging press, the plate is
gradually bent until the internal surface of the annular wall so formed begins
to bear on the feeding mandrel (/) whilst in the succeeding portion of the dies,
which forms a multiple hammer device with decreasing apertures, the annular
wall of the hollow body is lengthened by simple forging until the required wall
thickness is produced.
2. Apparatus for manufacturing metallic hollow-ware constructed, arranged,
and operating substantially as hereinbefore described with reference to and
shown in the accompanying drawings.
3. The improved method of manufacturing metallic hollow-ware hereinbefore
set forth.
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.