Electrically Heated Matrix Press.
Year: 1892

page_text: Date of Application 17th May, 1892-Accepted, 18th June, 1892
COMPLETE SPECIFICATION.
Electrically Heated Matrix Press.
I WILLIS MITCHELL of Malden, in the County of Middlesex, State of
Massachusetts, United States of America, Electrician, 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 :-
This invention has for its object to provide satisfactory means for drying
matrices by the passage of an electric current and the heat which it causes.
In obtaining the impression of type on a matrix for casting stereotype plates
the usual present practice is as follows:-A suitable moistened paper sheet is
laid upon the chase of type and rolled down until the paper has received the
impression; then the chase with the matrix still on it is. removed to a press,
the lower bed-plate of which is heated by steam circulating through it; the heat
ascends through the type and after a certain length of time reaches and dries
the matrix. The incidental heating of the type is quite objectionable on account
of the expansion and contraction which consequently occur.. Another objectionable
feature of the practice above described is the necessity for two separate operations,
the rolling and the drying and pressing. My invention eliminates both of these
defects, securing rapidity and perfection of work, performed by one machine
instead of two.
In the accompanying drawings,
Figure 1 represents a perspective end view of a machine embodying my
invention, the platen and its supporting bar having been removed and a part of
the bed broken away;
Figure 2 represents a detail view of the platen;
Figure 3 represents a similar view of the hollow interior thereof, showing the
conical studs which receive the electric heating cylinders, the cover having been
removed;
Figure 4 represents a detail view of one of the said heating cylinders in vertical
section;
Figure 5 represents a detail view of the same in elevation, with the covering
removed;
Figure 6 represents a view of the same in horizontal position, the end cap of the
covering alone being removed;
Figure 7 represents a perspective detail view of the cover of the platen ;
Figure 8 represents a detail view of the rack-bar for raising and lowering the
said platen; and
Figure 9 represents a side perspective view of the entire machine, also showing
the movable table on which the chase of type is brought to it.
In the said drawings, A designates the frame of the press, provided with legs a
and raised standards A', the latter being connected by an arched top-piece A' and
a bracing cross-bar A³. In these standards a transverse driving shaft Bis
journaled, which is provided at one end with a crank-handle B¹, at the other end
with a chain-wheel B³, and near its middle with a pinion B. An endless chain e
runs from the said chain-wheel to a similar chain-wheel or pulley D' on a trans-
This shaft is provided
verse shaft D, journaled in one end of the said frame A.
near its ends with two more chain-wheels or pulleys D2, D³, which receive endless
horizontal chains E, E' for feeding the chase into position to impress the matrix.
At the other end of the said frame, these chains pass around the chain-wheels E³, E'
journaled therein.
The pinion B³ meshes with a vertical rack-bar F which moves up and down in
guides attached to the said arched top-piece A² and cross-bar A³. The lower

page_text: end of this bar is provided with a stud or reduced extension F", which is perforated
from side to side at f', a collar F' being formed on the said bar just above it.
This stud fits into a socket G which is attached to the top plate or cover of the
platen, the said socket being also perforated at g, so that a pin may be passed
through both the said stud and the said socket, fastening them together.
The platen is hollow and consists of a top-plate or cover H' and a hollow
body H, the latter having tapering studs raised thereon, each of which receives
one of the electrical heaters hereinafter described. When these two parts H
and H are put together and bolted or otherwise fastened, they constitute a shell.
enclosing the electric heating devices, the said shell being also of sufficient
weight for service as a platen. The pressure of it on the matrix is chiefly pro-
duced by so turning the crank-handle B as to lower the said rack-bar and platen.
This pressure may be increased by a lever I, which is pivoted at one end to the
said top-piece and arranged to bear on the top of the said rack-bar when the said
lever depressed.
J designates the electrical heaters employed for the said platen. Each of these
consists of a conoidal shell having within it a series of concentric insulating
partitions of corresponding shape. A wire K, forming part of an electric
circuit, is wound about the innermost partition from end to end of the latter.
Then the next outer partition is slipped over it and the wire is wound on this from
end to end in the reverse direction. This is repeated with each partition until the
outer one is similarly wrapped, when the wire is carried to the next heater and the
same procedure is repeated. Thus all the wire helices of all the heaters are in
the same electric circuit, and the passage of the current through them heats the
studs on which the said heaters are fitted, and also the body of the platen. The
wire K may have an insulated coating, or be wound so tightly into the materials of
the partitions that its individual coils or windings cannot come in contact with each
other; or strips or pieces of insulating material may be inserted between them.
Any of these plans will avoid short-circuiting. The material of the partitions is
preferably asbestos. Their shape and that of the studs h and heaters J as entire-
ties need not be conoidal. Cylindrical studs and heaters would answer, but the
conoidal ones fit more securely.
To permit the escape of moisture from the matrix through the bed L of the
press under pressure, the said bed is provided on its under side with a series of
longitudinal grooves L', and cach groove of this series has a saw-kerf / running
lengthwise of it and extending to the surface of the said bed.
As shown in Figure 9, the chase M of type is brought in from the composing
The end of this table
room on a movable table or truck N running on wheels n.
or truck fits against the end of the frame A, as shown. The said chase is provided
with hooks m which catch into the endless horizontal chains E E. The shaft B
is then operated to lower the said platen and at the same time cause the said
chains to feed the said chase under it. When the chase is fully in position under
the platen, the hooks m are released by hand from the horizontal chains E E¹.
Before the platen is fully lowered, the moistened matrix is placed on the type, a
blanket or layer of soft felt or equivalent material is placed on the matrix and on
the blanket a sheet of asbestos mill-board. The electrically heated platen is then
brought down on the mill-board, and additional pressure, if needed, is applied by
the lever I or any equivalent device which may be substituted therefor.
Having now particularly described and ascertained the nature of my said inven
tion, and in what manner the same is to be performed, I declare that what
claim is :-
1st. In a matrix-press, the combination of a platen having studs formed on it
with electric heaters fitting on the said studs, each of the said heaters being
formed of a wire wound on successive cylindrical or conoidal walls, and the said
wire being in an electric circuit, substantially as set forth.
2nd. In a matrix-press, the combination of a hollow platen with a series of

page_text: electrical heaters arranged within it, each heater consisting of several concentric
layers and a wire wound thereon in successive helices, the same wire extending
throughout the series and forming part of an electric circuit, substantially as set
forth.
3rd. In combination with a shaft pinion and rack, a platen raised and lowered
thereby, a lever arranged to apply additional pressure to the said platen, a matrix
supporting bed and electrical heating devices arranged within the said platen for
the purposes set forth.
4th. In combination with a platen having studs h raised within it, a series of
electrical heating devices formed of a wire which is in an electric circuit, the said
wire being wound on successive concentric cylindrical or conoidal layers of asbestos
and properly encased for each electric heater, the said heaters fitting on the said
studs and all being in the same electric circuit, substantially as set forth.
5th. A platen provided with a raised stud in combination with an electric heating
device adapted to fit on the said stud, the said device consisting of a concentric
series of insulating partitions properly encased and a wire which forms part of an
electric circuit and is wound successively on these partitions, substantially as set
forth.
WILLIS MITCHELL,
F. W. Golby,
36, Chancery Lane, London, W.C., Patent Agent for the Applicant.