IMPROVEMENTS IN THE MANUFACTURE OF STEAM DOMES, AND IN THE TOOLS OR APPARATUS EMPLOYED THEREIN
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by Joseph Thomas Andrews at the Office
of the Commissioners of Patents on the 30th January 1880.
JOSEPH THOMAS ANDREWS, of Handsworth, in the County of Stafford, Manager
of Works. "IMPROVEMENTS IN THE MANUFACTURE OF STEAM DOMES, AND IN THE
TOOLS OR APPARATUS EMPLOYED THEREIN."
My Invention relating to the manufacture of steam domes, and the tools or
apparatus employed therein, consists of improvements whereby the operation is
facilitated, and economy in the cost of manufacture is effected.
In carrying out my Invention I cut out from wrought iron or other metal
suitable for manufacturing steam domes a circular disc or blank of the required
size, and I preferably give the said disc or blank such a sectional figure that its
edges or marginal parts are thinner than the middle part of the disc or blank. The
circumferential or marginal parts of the blank or disc having been heated the said
blank is operated upon in succession by a series of two or more drawing through
dies, and a shaping or finishing die in conjunction with a punch or plunger, the said
punch or plunger forcing the blank or disc into the dies and thereby forming it
into a dome. Each of the drawing through dies is hollow, and the said hollowed
part is tapered, the taper progressively diminishing from the first to the last die,
which has a closed hemispherical bottom. The punch used in the first stages of
the shaping process may either be conical or cylindrical, but the punch at the
finishing stage is cylindrical, and its end corresponds in figure to the closed bottom
of the last or finishing die used.
By the operation of the taper dies and their plungers or punches the heated
marginal parts of the blank are first gathered in and a cupped taper figure given
to the said blank, and by the operation of the cylindrical or finishing die and its
punch the taper figure of the partly made dome is converted into a cylindrical
figure and a hemispherical bottom given to the said dome.
In order to facilitate the removal of the punch or plunger from the shaped article
I preferably make the said punch or plunger in three or more segmental parts,
expanded by means of wedges. By removing these wedges the punch contracts
and may be readily withdrawn from the shaped article.
The cylindrical portion of the dome having been thus formed I employ the
following tools or apparatus in order to form a flange round the outer edge of the
dome: The dome is placed in a hollow cylindrical mould having its upper rim of

page_text: the same curvature as the required flange. A sufficient portion of the cylindrical
part of the dome projects from the mould to form the flange. A. conical tool is
then caused to press on and expand the said projecting portion into a trumpet or
bell mouthed shape. Finally, a mould or die having its pressing surface corre-
sponding both to the finished flange of the dome and the upper rim of the mould
is caused to press on the aforesaid projecting portion of the dome so as to give it
the required shape and curvature. (The conical tool hereinbefore described for
expanding the mouth of the dome may either form part of the mould or die, or it
may be a separate tool.)
The said mould or die is provided with a rim round its outer edge which confines 1
the metal while being pressed, thereby preventing it from spreading laterally, and
thus a full thickness of metal in the finished flange is ensured.
In operating the tools both for forming the cylindrical portion of the dome and
for forming a flange thereon I prefer to employ hydraulic pressure.