Improvements in Method of and Means for Manufacturing Rubber Stamps.
Year: 1893

page_text: Date of Application, 8th Mar., 1893-Accepted, 3rd Mar., 1894
COMPLETE SPECIFICATION.
Improvements in Method of and Means for Manufacturing Rubber
Stamps.
A communication from GEORGE JAMES BELLAMY RODWELL, of Buffalo, County
of Erie, State of New York, United States of America, and SAMUEL JAMES
MOORE and HERBERT C. SECORD, both of Toronto, County of York,
Province of Ontario, Canada.
I, ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
Chartered Patent Agent, 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:--
In practising this said invention, a matrix or mould of plastic cement is first
prepared, then impressing therein the facsimile of the face of the stamp to be
produced, then heating and hardening said matrix or mould, then placing thereon
a sheet of rubber, and applying to the top thereof a heated press-plate and, while
applying the pressure to the said plate, maintaining the matrix or mould at a
vulcanizing heat. For this purpose it is preferred to employ the apparatus
illustrated in the annexed drawings, in which
"Figure 1 is a side elevation showing the apparatus in its condition for the com-
mencement of this process of manufacturing stamps of vulcanized rubber;
Figure 2 is a central longitudinally vertical section showing said apparatus in
5-its condition during the second step of the aforesaid process ;
Figure 3 is a longitudinal section showing said apparatus in its condition for the
third step of the process, and
Figure 4 is a vertical transverse section illustrating its operation in completing
the aforesaid process.
A represents an elongated horizontal bed, from opposite sides of which rise
two walls formed with parallel longitudinal guides B B at their tops. Over one
end of the aforesaid bed is arranged a suitable press-head or follower P of a
press. The said press-head is adapted to be raised a sufficient distance above the
guides B B to permit the following devices to be placed under the press-head.
5 Upon the guides B B is mounted a table C which is movably longitudinally to
and from under the aforesaid press-head.
D represents a metallic pan in which is formed the mould or matrix for. the
stamp to be formed as bereinafter explained. The said matrix is formed by filling
the pan with plastic cement preferably composed of plaster of Paris mixed with
O sufficient clay or other material to retard the setting thereof without impairing
its rigidity when set. a designates the aforesaid plastic cement in which is made
an impression of the fac-simile of the face of the stamp to be produced. When
the said impression can be made by printer's type tt the said types are placed into
a chase I and firmly secured therein in the usual manner. This chase with its
5 type secured thereto is placed upon the table C with the types tt facing upward
and then the pan is placed in an inverted position with the plastic cement adhering
thereto upon the face of the aforesaid types which latter had previously been faced
with suitable oil to prevent the cement from adhering to them. The table C
is then pushed along on the guides B B so as to bring the pan D directly under
0 the press-head P as indicated by dotted lines in Figure 1 of the drawing,
The press is then operated to bring the press head down upon the pan with
sufficient pressure to properly make the impression of the types in the cement.
The interior of the pan is roughened to obtain a sufficient hold upon the cement
to prevent its dropping out of the pan in the operation of inverting the latter.

page_text: In order to gauge the movement of the press head so as to prevent undue
pressure on the plastic cement and impart the proper thickness to the mould a
collar is attached to the screw of the press and this can be so adjusted that by
contact with the top of the press-frame it arrests the movement of the screw, as
represented in Figure 2 of the drawing.
After the impression has thus been made in the plastic cement the press head or
follower is raised and the table C, with the chase I and pan D drawn back from
under the press as illustrated by full lines in Figure 1 of the drawing. The pan D
is then removed from the chase I and the latter is removed from the table C, the
pan D is then replaced with its back upon the table C, and the cement heated and
dried in the pan by placing under the table a lighted lamp or other suitable movable
heater H as shown in Figure 3 of the drawing. To allow the table to conduct
the heat more quickly to the pan said table is formed hollow or with a cavity C¹ in
its under side. After the pan with mould has been sufficiently dried and heated
the lamp or heater H is transferred to a position directly under the press-head or
follower P and the press-head brought down as indicated by dotted lines in said
Figure 3 and thereby the said press-head is heated to the proper vulcanizing heat.
In the meantime there is placed upon the matrix formed of the hardened cement
in the pan a sheet of rubber and the top of the said rubber sheet is covered with
paper or cloth. The press-head is then raised and the table with the matrix
resting thereon pushed forward under the said press-head, and then the press is
operated to cause the press-head to press upon the rubber with sufficient force to
cause the matrix to make its impression in the rubber.
In order to ensure a uniform thickness across the entire length and width of the
compressed rubber, there is attached to opposite sides of the table C, gauges c c
with which the press-head comes in contact when brought down the desired
distance as represented in Figure 4 of the drawing.
During this latter step of the process, the lamp or heater is maintained under
the table for a sufficient period to vulcanize the sheet of compressed rubber. After
this is effected the light is extinguished or the heater removed and the press-head
raised and then the table C is drawn back and the vulcanized rubber sheet is
removed from the matrix.
Having now particularly described and ascertained the nature of this said inven-
tion as communicated to me by my foreign correspondents, and in what manner
the same is to be performed, I declare that what I claim is :-
1. The process of manufacturing stamps of vulcanized rubber consisting in
preparing a mould of plastic cement then impressing therein a fac-simile of the
face of the stamp to be produced, then heating and hardening said mould, then
placing thereon a sheet of rubber and applying to the top thereof a heated press
plate and while applying pressure to said plate maintaining the mould at a vulcanized
heat as set forth.
2. The within described apparatus for manufacturing stamps and analagous
articles of vulcanized rubber consisting of an elongated bed a press-head and
follower over one end of said bed longitudinal guides above the bed a table mounted
on said guides movably to and from under the follower of the press a matrix
mounted on said table and a heater arranged between table and bed and movable
longitudinally as set forth.
Dated this 8th day of March 1802
W. P. THOMPSON & BOULT,
London, Liverpool, Manchester, and Nottingham,
Agents for the Applicant.