Improvements in the Manufacture of Polished Sheet Iron.
Year: 1888

page_text: COMPLETE SPECIFICATION.
Improvements in the Manufacture of Polished Sheet Iron.
I ALBERT EDGAR ALEXANDER of 19 Southampton Buildings in the County of
Middlesex do hereby declare the nature of this invention communicated to me from
abroad by Isaac E. Craig of Camden in the county of Preble and State of Ohio in
the United States of America and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement :-
--
Heretofore the sheets of Iron and sheets of Mild Steel to which this invention
equally applies, intended for the purpose of afterwards being polished, have been
rolled in plain and smoothly dressed rolls, or otherwise in chill, or soft cast rolls,
whose surfaces have been allowed to become somewhat mottled or pitted as a natural
incident and result of considerable use in drawing bars and slabs down to sheet while
at a red heat.
The object of the first step of my invention herein described is to produce sheets
having such a mottle or irregularity of surface as renders them more easily polished
under the action of the hammer used for that purpose.
It has also heretofore been practiced to polish such sheets by hammering them for
a considerable time under hammers having their operative faces plain or marked into
a surface of an irregular mottle, and the second step of the method herein described
is such a modification of the face of the dies of the hammer as renders their action in
producing a lustre more rapid and reliable without the need of striking blows so heavy
as to be rapidly destructive of the hammer itself.
To carry my invention into effect I choose rolls cast with either a very mild chill or
those known as sand rolls having no chill, and after they are turned to the proper
form for the rolling they are intended to perform, I have their surfaces mottled by
hammering in the following manner :-
I first prepare hammers of good steel weighing about one pound each, having small
oval faces at each end of a diameter of from one-eighth of an inch to one fourth of an
inch, the smaller dimension being preferable.-Workmen then go over the entire
surface of each roll with these hammers, or the same purpose may with less beneficial
result, be produced by marking but one of the rolls, and so hammer them that the

page_text: marks of the small oval faces will be made from one-fiftieth to one-hundredth part of
an inch in depth, or of a depth from one half the thickness of twenty six guage sheet
iron to that of the entire thickness of this guage. The marks should approach each
other so nearly as to be at no place more than one fourth of an inch apart; but
regularity is not necessary and an ordinary workman can make the marks with sufficient
accuracy striking from one hundred to one hundred and fifty blows per minute. This
will ordinarily require the work of one man for six or seven days on a pair of rolls
twenty one inches in diameter and thirty six inches long.
The rolls so marked are then used in the ordinary manner of hot finishing rolls, or
as I much prefer, on account of durability of the marks, and character of the work
done, may be used, if originally turned with their faces straight so as to be parallel in
the housings, as cold rolls, and have the sheets passed between them one, or at any
rate, not more than two, at a time. For the most beneficial effect on the after working
of the sheets, they should, after being drawn in the hot rolling to approximately the
guage desired be cleaned by either the pickling process with acid, or by reviving the
scale by heating for several hours in contact with some solid or gaseous deoxidising
agent, as is understood in the art, and then passed singly between the marked cold
rolls, the upper one of which is so screwed down as to produce on each surface of the
sheet a roughness or mottle plainly perceptible to the touch of an ordinarily sensitive
finger; but this depth of mottle may be varied by the amount of pressure or screw
used, to suit the taste of the manufacturer, after which and irrespective of the
intermediate treatment to which the sheets may be subjected when they come to the
hammering operation, I find great benefit to result from having the otherwise plain or
mottled surface of one or both dies of the hammer divided into comparatively narrow
and parallel strips or facets. The hammers ordinarily used for this purpose carry dies
having faces eighteen inches square, and strike a blow of from five thousand to fifteen
thousand foot pounds on packages ranging from sixty to one hundred and twenty
sheets, which have been heated to low redness. I have found in practice that owing
to the great area of the operating surfaces and the low heat of the sheets being acted
upon that by much the larger part of the force of these blows is transmitted through
the anvil block to the foundations below, and that to greatly reduce the width of the
faces of the dies by inviting the upper die to rock or tilt, injures the work and is also
very injurious to the durability of the hammer, all of which difficulties I am enabled
to overcome by dividing the face of one or both dies into narrow parallel faces, and
for this purpose, prefer and find it best to limit the division of face to the upper or
active die. This I accomplish by dressing the die with a planer or cold chisel, so that
about one half of its surface will be removed in grooves from one inch to three inches
wide and about one twentieth of an inch in depth. The width of the grooves and
also of the remaining faces or facets may be varied within wide limits but for a
hammer of six thousand or seven thousand pounds head I prefer that they should
be about two inches wide. Substantially the same purpose is accomplished by fitting
the face of the upper die with a hood, or false face, consisting of a piece of eighteen
or twenty guage mild sheet steel, cut into grate form having spaces of two inches
remaining as bars, and two inch spaces removed, with edges dressed oval. In
operating the hammer so faced it is necessary that the package should be slowly
drawn over the anvil, and have a motion not exceeding one fourth of an inch between
blows of the hammer. This 1 accomplish by means of a capstan windlass or equivalent
mechanical means, using a pair of sirong tongs with extremities of handles linked
together for the grip. It is also found beneficial on the third or last hammering to
use a hammer having wider faces than two inches as above described or otherwise to
change the mask or hood on die of same bammer, for one of wider bars; and for this
purpose recommend but two bars, one at each side of the die, five inches in width.
The direction of these parallel faces should always be such that their length lies
cross wise with the sheets worked under them.
By means of the joint benefits of above described changes, namely the mottling of
the sheets and the subdivision of the operating face of the hammer, I am enabled to
reduce the heighth of blow required from three fourths to five sixths and more than

page_text: proportionately reduce the hammer breakage, which in this class of work is a large
element of expense, and at the same time somewhat increase the amount of lustre
obtained on the sheets.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. As an improvement in the manufacture of polished sheet iron, passing the sheets
between hot or cold rolls artificially marked as described, preliminary to polishing in
packages under the hammer.
2. Polishing sheet iron by the action of a hammer, or hammers, on packages of
sheets with the operating faces of one or both dies of the hammer subdivided into
parallel lines as described.
3. A process of manufacture of polished sheet iron consisting first in marking the
sheets with artificially mottled rolls and secondly, irrespective of intermediate steps,
polishing by hammers having their die faces divided into parallel lines as described.
Dated this 15th day of March 1888.