The Memphis union appeal. [volume] (Memphis, Tenn.) 1862-1862, 1862-08-07
From the Scientific Americana -.. ...... .f.,
Iron.Clad Frigates-Bending their Armol
@ Plates.

Iron.Clad Ffigates-B ending & their rmor
MS Plates.
The steam frigate Roanoke, which is now in
the navy yard at Brooklyn, has been raced,
and is being converted into an iron-cad turret
war-ship. She is to be clothed amidships with
thick iron plates which are to extend five feet
below the water-line; and she will have three
great revolving gun turrets on deck, and a
powerful iron beak or ram on her bow. This
beak resembles huge axe, and is formed of
plates twenty feet long, four and half inches
thiek--thus making nine inches of iron on the
front edge Each of the revolving gun turrets
wih be twenty feet inside diameter, and the
sides viii be formed Of eleven courses of inch
iron plates.
These plates are laid over and rivited to one
another in such a manner as to break Joints, y
and her vertical plates are also bolted to sew
eral courses so as to secure the whole in the
most rigid and perfect manner. These gun
towers for the Roanoke are now being con-
structed at the Novelty Works, in this city,
where the plates for them, likewise those for
the armor, are bent to the proper curves. Each
plate for turret is abolt nine feet in length by
forty inches in width, and an inch in thickness
Two courses of riyet holes are punehed out in
each, and they are all bent cold in powerful
hydraulic press. The bed plate of the press Is
of concave form, and top block is of a convex
form. nj . 1 p
| a plate to be bent is placed upon the con-
cave bed-plate of the press, and when properly
adjusted, the pump forces up three rams under
it, and the plate is reduced to the proper curve
against the top block. The pressure to which
each plate is submitted, to give it the proper
curve is three and a half million pounds. By
this method of bending the turret plates cold,
there is perfect uniformity and accuracy se-
cured to the whole. The turrets for the Roa-
noke will be of a superior character, but only
six courses of plate have as yet been laid on
two of them. HgE
| The bending of the thick plates for the ram,
and also for the sides of the frigate, is quite a
1 different and difficult operation to perform
I compared with those of the guntowers. Each
of these plates has to be bent to the proper
curve to suit its own particular place on the
vessel, and not only the broad side but the edges
also must be bent to suit the particular curves.
I The bending operations are under the charge
of Mr.. George Bonniwell an intelligent young
shipwright. All these plates are hammered
| iron, and are furnished by several companies in
Pennsylvania, New York and Massachusetts,
| When they arrive they resemble huge straight
| iron slabs, varying in length from eleven to
Twenty-Five feet, and in breadth from twenty
| two to twenty-four inches, and their average
/ thickness is four and half inches. One OF
! eleven and half feetin length weighs about
| 4,240 pounds; one of twenty-five feet, for the
! ram, weigh over four tons. Such masses OF
iron are difficult to move about, and the oper.
ations connected with bending them are
necessarily tedious and troublesome; and they
REQUIRE great care and skill to perfect
them OF course it is impossible to bend such
masses of iron cold, hence each plate is first
/ heated to nearly white heat in a large fur.
mace, shaped somewhat like q bakers oven
4 with movable arched cover.
The press for bending is quite different
from the one used for the turret plates. Out
wardly it resembles long, strong iron screw
press, used for pressing woolen cloth. Its tor
llbloek, or platen, is moved up and down. Tht
bed upon which the heated plate is laid, il
5 formed of series of adjustable bolster blocks
each of which is capable of being set by
screw to aay desired height on either side
and at any angle to suit the bendto be given t
s q plate which is compressed between the de
cending block and the adjustable bed. Aplat
in first placed in the furnace, and it is thei
|. raised to nearly white heat The cover o
the furnace is now raised by q block and tackle
and the plate is then seized by 8 powerful
crane, secured on carriage. The heated plat
, il now lifted, the crane and carriage move
& back, and the plate swung around and place
! IN the press, where il is perfectly adjusted t
81 obtain the proper curves. The hugetop- bloc
/ |. Is then ferced down, squeezing the great mas
, of iron into the desired shape. 1855
II In about half an hour the plate has acquire
|, a permanent set, and it is taken out, ready {
have its edges planed, when it is tit for boltin
( TO the ffigate. The bolt holes in these plate