IMPROVEMENTS IN MACHINERY FOR FORGING, STAMPING, TILTING, SWAGING, HAMMERING, OR PLANISHING METALS
Year: 1869

page_text: LETTERS PATENT to Joseph Mitchell, of Sheffield, in the County of
York, Engineer, for the Invention of "IMPROVEMENTS IN MACHINERY
FOR FORGING, STAMPING, TILTING, SWAGING, HAMMERING, OR PLANISHING
METALS.
Sealed the 7th January 1870, and dated the 18th August 1869.
PROVISIONAL SPECIFICATION left by the said Joseph Mitchell at the
Office of the Commissioners of Patents, with his Petition, on the
18th August 1869.
I, JOSEPH MITCHELL, of Sheffield, in the County of York, Engineer,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
MACHINERY FOR FORGING, STAMPING, TILTING, SWAGING, HAMMERING, OR PLANISHING
METALS," to be as follows:-
My Invention relates to that class of machinery used for forging,
stamping, or hammering in which a number of blows are made singly
trip
or in rapid succession. These machines are usually termed "
hammers."

page_text: In my improved machine the hammer head which carries the striking
tool works up and down in vertical guides, and is made hollow so as to
receive a cam or set of cams or one or more excentrics whereby the
hammer head is lifted. Immediately below the cam or cams is fixed a
strong transverse bar, which passes through the hammer head and acts
as a point of resistance for a strong coiled spring, one end of which
bears against the under side of this cross bar while the other rests upon
the lower part of the hammer head. A fly wheel shaft carries the cam
cr cams or excentric or excentrics, and it is operated from any prime
mover by means of a clutch arrangement which may be thrown in or
out of gear when required by means of a hand lever or treadle. As the
cam or cams or excentric or excentrics and the coiled spring are all
placed within a space in the hollow hammer head they may be covered.
up with a plate and screened from view and thus be preserved from
dust and damage.
I find it convenient to employ a series of three or four cams or
excentrics so as to produce a rapid succession of blows, but a lesser or
greater number may be used according to the kind of article intended
to be produced.
It will be understood that the cams or excentrics will by their
rotation lift the hammer head, which will when released fall by its
own weight, but the coiled spring will give intensity to the blow.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Joseph Mitchell in the Great Seal Patent Office
on the 18th February 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH
MITCHELL, of Sheffield, in the County of York, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of August, in the year
of our Lord One thousand eight hundred and sixty-nine, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Joseph Mitchell, Her special licence,
that I, the said Joseph Mitchell, my executors, administrators, and

page_text: assigns, or such others as I, the said Joseph Mitchell, my executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN MA-
CHINERY FOR FORGING, STAMPING, TILTING, SWAGING, HAMMERING, OR PLANISHING
METALS," upon the condition (amongst others) that I, the said Joseph
Mitchell, my executors or administrators, by an instrument in writing
under my, or their, or one of their hands and seals, should particularly
describe and ascertain the nature of the said Invention, and in what
manner the same was to be performed, and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Joseph Mitchell, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement, reference being had to the Drawing hereunto
annexed, and to the letters and figures marked thereon (that is to
say) :-
My Invention relates to that class of machinery used for forging,
stamping, or hammering in which a number of blows require to be
made in rapid succession. These machines are usually termed "trip
hammers."
My improved machinery is shewn in the accompanying Drawing, in
which Fig. 1 is a front elevation of the machine; and Fig. 2 is a side
elevation of the same.
The hammer head a which carries the striking tool works up and
down in vertical guides b, b, and is made with a hollow space so as to
receive a cam or set of cams c (or one or more excentrics may be
employed) whereby the hammer head a is lifted in its guides. Imme-
diately below the cam or cams which are mounted on the main shaft d
is fixed a strong transverse bar e which passes through the hammer
head and acts as a point of resistance for a strong coiled spring f, one
end of which bears against the under side of this cross bar e while the
The fly wheel
other rests upon the lower part of the hammer head a.
shaft d which carries the cam or cams or excentric or excentrics is
operated from any prime mover by means of a clutch arrangement g,

page_text: which may be thrown in or out of gear when required by means of a
hand lever or by a treadle h as shewn, at Fig. 2. This clutch arrange-
ment consists of a sliding block g, in the face of which one or more
pins i, i, may be fixed. These pins pass through the fly wheel j, which
is always kept in motion by means of a band passing round it or
otherwise, and when the treadle lever his depressed the clutch block g
with its pin or pins i is pushed forward so that one of the pins i will be
brought in the way of another pin k on a disc or block k¹ on the shaft d;
so long therefore as the treadle his depressed the shaft d with its cams or
excentrics will be carried round, and will cause the hammer block a
to strike a rapid succession of blows, but immediately the treadle is re-
leased the clutch block g will be forced back by the strong spring 1, and
as the pins i will be withdrawn from contact with the pin k of the
block k', the shaft d and the cams c will be stopped. As the cam or
cams c, and the coiled spring f are all placed within a space in the
hollow hammer head a, they may be covered up with a plate and screened
from view, and thus be preserved from dust and damage. If desired an
excentric or excentrics may be mounted on the shaft d instead of the
cams c, as shewn in the detached view Fig. 3, of the hammer block, and
then the machine may be used as a punching machine. I find it con-
venient to employ a series of three or four cams or excentrics, as shewn
in the Drawing, so as to produce a rapid succession of blows, but a
lesser or greater number of cams or excentrics may be used according
to the kind of work or article intended to be produced. It will be
understood that the cams or excentrics will by their rotation lift the
hammer head a, which will when released fall by its own weight, but
the coiled spring f will give intensity to the blow. Fig. 4 is a front
view of a machine, in which in combination with the cams c and coiled
spring already described and shewn by dots in Fig. 4, there is an
additional elliptic spring m placed on the top of the machine, and made
to act on the upper end of the hammer block for the purpose of increasing
the intensity of the blow if required.
Having now described my Invention of "Improvements in Machinery
for Forging, Stamping, Tilting, Swaging, and Hammering, or Planishing
Metals," and having explained the manner of carrying the same into
effect, I claim as the Invention secured to me by Letters Patent as
aforesaid, the arrangement or construction of parts herein shewn and
described for working the hammer or any mere modification thereof in

page_text: which the hammer is operated by the combined act of a cam or excen-
tric and a spring or springs, as herein set forth.
In witness whereof, I, the said Joseph Mitchell, have hereunto
set my hand and seal, the Sixteenth day of February, in the
year of our Lord One thousand eight hundred and seventy.
Witness.
Jos. BIRAM,
Cashier,
Napier Works,
Sheffield.
(L.8.) JOSEPH MITCHELL.