IMPROVEMENTS IN APPARATUS FOR THE MANUFACTURE OF DENTAL. PLATES OR OTHER ARTICLES OF CELLULOID, INDIA-RUBBER, OR THE LIKE."
Year: 1882

page_text: LETTERS PATENT to John Hutchens Gartrell, of Penzance, in the County of
Cornwall for an Invention of "IMPROVEMENTS IN APPARATUS FOR THE
MANUFACTURE OF DENTAL. PLATES OR OTHER ARTICLES OF CELLULOID,
INDIA-RUBBER, OR THE LIKE."
PROVISIONAL SPECIFICATION left by the said John Hutchens Gartrell at
the Office of the Commissioners of Patents on the 5th August 1882.
JOHN HUTCHENS GARTRELL of Penzance in the County of Cornwall IMPROVE-
MENTS IN APPARATUS FOR THE MANUFACTURE OF DENTAL PLATES OR OTHER
ARTICLES OF CELLULOID, INDIA-RUBBER OR THE LIKE
"
"
My invention relates to apparatus for moulding, under pressure, celluloid, india-
rubber, or the like and is chiefly designed for the manufacture of dental plates. In
the class of apparatus to which my said invention appertains the celluloid or other
plastic material is forced or injected from a cylinder or tube into the mould after
the flask containing the same has been placed in the boiler or heater and tightly
closed. When india-rubber is used for forming the said plates, they may be
vulcanized without removing the mould from the boiler or heater.
According to my said Invention provide improved means whereby the
mould can be tightly closed after it has been placed in the boiler or heater, and I
construct the apparatus in such a manner that it can be heated either by steam or
hot air. I also provide means whereby, in the latter case, I can obtain the
necessary steam-pressure for indicating the temperature upon a gauge and for
regulating the supply of gas to the burner, if desired. And I construct the
injecting cylinder or tube in an improved manner to facilitate the manipulation of
the apparatus.
In carrying the said invention into practice the boiler or heater is supported
upon a closely fitting stand or casing which surrounds the burner and the boiler
or heater, and holds the latter at a sufficient height above the burner. The effect
of this casing is to retain the heated air around the exterior of the boiler. The
מ

page_text: upper part of the boiler is closed by a plate having preferably three screw-threaded
holes to receive screwed studs. These studs have square heads upon which a key
can be fitted for screwing them down tightly upon the flask containing the mould.
Above the said plate the boiler is adapted to receive a steam tight cap or cover.
The flask containing the mould is placed in the boiler through an opening at one
side provided with a steam-tight cap and also with a cap designed to be used
when dry heat is employed and the flask is secured upon one end of the injecting
cylinder which projects inwardly from the opposite side of the boiler and is fixed
therein. At one side of the boiler or heater I sometimes provide a chamber having
a steam-tight cover or stopper and in the upper part of this chamber I fix one end
of a pipe leading to a steam-gauge or to apparatus for regulating the supply of gas
to the burner by, and according to, the pressure of steam within the said chamber.
The injecting cylinder or tube is constructed with an aperture into which a rod or
plunger is adapted to be inserted when the screw is withdrawn to a sufficient
extent, and the said rod or plunger can then be moved towards the mould, by means
of the screw, to compress the material in the said mould. The boiler or heater is
provided with a safety-valve and with means for allowing the air to be driven out
by the steam when the latter is used as a heating agent.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Hutchens Gartrell in the Great Seal Patent Office on the
5th February 1883.*
"
JOHN HUTCHENS GARTRELL, of Penzance, in the County of Cornwall. IMPROVE
MENTS IN APPARATUS FOR THE MANUFACTURE OF DENTAL PLATES OR OTHER
ARTICLES OF CELLULOID, INDIA-RUBBER OR THE LIKE"
My invention relates to the moulding, under pressure, of celluloid, india rubber
or the like, and is chiefly designed to provide improved apparatus for manu̟-
facturing dental plates of such materials.
In this class of apparatus as commonly heretofore constructed, the flask
containing the mould is placed in a boiler or heater and tightly closed by a screw.
and plunger; the celluloid or other plastic material is then forced or injected from
a cylinder, or tube into the said mould, after which the boiler is partly filled with
water and heat is applied, thereto, usually by means of a gas-burner, the steam
coming in contact with the flask; and, when india rubber is used for forming the
said plates, they are vulcanized without removing the flask from the boiler or
heater. Apparatus of this kind is described in the Specification of my former
Letters Patent dated 27th October A.D. 1877. N° 3986.
The
According to my present invention I construct the apparatus in the following
manner, that is to say: To permit the boiler to be conveniently heated either by
steam as above described, or by hot air, I provide the same with an additional
chamber which has no communication with the chamber in which the flask is
placed. This additional chamber is intended to contain water which will be
converted into steam when heat is applied to the boiler, and I sometimes connect a
steam gauge with the said chamber so that the temperature of the boiler or heater
can be ascertained approximately by the pressure indicated upon the gauge.
steam from this chamber can also be employed for operating a gas regulator, such
as that described in the said former Specification, for regulating the supply of gas
for heating the boiler, in order to maintain a uniform temperature therein. I
form a box or casing upon the top of the boiler and provide the said casing with
a steam-tight cover, so as to enclose the screws which I employ for closing and
securing the flask when in the boiler and thus prevent the escape of steam from
the apparatus through the holes in which the said screws are inserted.
In order to provide for ascertaining the temperature within the flask, I insert a
thermometer in the same after it is placed in the boiler. I also construct the
injecting apparatus, and connect the same with the flask through an aperture in the
side of the boiler, as hereinafter set forth, in order to facilitate the manipulation
of the apparatus. I sometimes combine with the cock or tap for the supply of gas
to the burner, an alarm clock provided with a device whereby the handle or lever
of the said cock will be held when the said cock is opened and will be released
when the alarm mechanism operates, so that it can then be moved by a spring to
close the cock. By these means I am enabled to regulate the length of time during
which heat is to be applied to the boiler.
In the accompanying drawing I have illustrated how my said invention may be
conveniently and advantageously carried into practice
Figure 1 represents a vertical central section of the boiler or heater and its
supporting shell or casing, showing also the flask in front elevation
Figure 2 is a plan of the same.
Figure 3, is a horizontal section of the boiler or heater showing the injecting
apparatus inserted therein and secured to the flask,

page_text: *. is a side elevation of the alarm clock and device for controming the gas
supply cock,
Figure 5 is a rear elevation showing the said device in the position it occupies
when the cock is opened, and
Figure 6 is a rear elevation showing the device in the position it occupies when
the lever is about to be released
..
Like letters indicate the same parts throughout the drawings
a represents the boiler or heater which is supported upon a closely fitting shell
or casing b. This casing is provided with an aperture or slot b' for the passage of
the pipe to the gas-burner, which is not shown in the drawing. The effect of this
casing is to retain the heated air around the exterior of the boiler or heater at its
lower part.
c is a tubular chamber extending down the side of the boiler, which
chamber may, if desired, also extend across the bottom of the boiler. This chamber
is intended, as above stated, to contain water and supply the steam required for
actuating a steam gauge and a gas regulator, and thereby automatically regulate
the amount of heat applied to the bottom of the boiler. By these means the
vulcanizing or moulding chamber and its contents may be heated uniformly by
dry heat," that is to say,-without steam being in contact with the moulds. When
it is desired to use the apparatus as an ordinary steam vulcanizer, water is poured
into the boiler to fill the spaces between the cross bars d at the bottom of the
boiler, and steam is generated therein to heat the moulds
<
The flask e is composed of two parts and is tightly closed when in the boiler by
three screws e¹ passing through the top of the boiler, above these clamping screws
is fitted a cover f, which is provided with a screw-thread fitting into a corre-
sponding internal screw-thread in the top of the box or casing f¹. This cover
forms a steam-tight joint and thus prevents the escape of steam from the boiler
around the clamping screws, when steam is employed in the moulding chamber.
These screws are also used to hold the flask in position whilst the celluloid or
india-rubber is being injected into the mould.
The injector or injecting apparatus for packing the mould is formed with a
barrel g in which a piston h and screw i are arranged as shown in Figure 3, and
with a cylinder j to contain the material for filling the mould. A hole is formed
in the side of the boiler opposite the door; through this hole the cylinder is
introduced and screwed into the flask. The piston h is formed with a slot as
shown by the dotted line at h¹, and a pin h² is inserted in the barrel g and projects
into: the said slot, so that the piston h is prevented from rotating but can be moved
longitudinally in the barrel g. The screw is formed with a fixed collar which
bears against the ring or collar screwed into the barrel g; the lever l is fixed
to the spindle of the screw i and bears against the other side of the collar i² so as
to prevent the longitudinal movement of the screw in the barrel and at the same
time permit its rotation therein. By means of the lever Z upon the end of the
screw 2, the said screw can be rotated to cause the piston to be moved into the
cylinder j and thus force the material into the mould. The flask is provided with
an outlet m, to show, by the protrusion of the material therefrom, when the mould
is full; and a pin is inserted to close this outlet when desired. The hole in the
side of the boiler is fitted with a suitable screw-plug to close it steam-tight when
the boiler is to be used as a steam vulcanizer
I sometimes use a thermometer p in addition to the steam gauge, in order to
indicate the temperature within the flask. The cover of the flask has a hole p¹ at,
or near, its centre. After the plaster of paris is poured into the flask to form the
mould, a pin is pushed through the hole p' in the cover of the flask into the soft
plaster, and when the plaster has set the said pin is withdrawn leaving a recess in
the mould to receive the thermometer, as shown in Figure 1.
Two doors are provided for closing the aperture through which the flask is
introduced into the boiler, the door is provided with a glass window r¹, to
permit the inspection of the thermometer when dry heat is employed, and another
door is made entirely of metal for use when vulcanizing with steam. These doors

page_text: are secured in position by a cross-bar or bridge t and a central screw u in the
ordinary manner. A safety valve is provided at v in the ordinary manner.
In Figures 4, 5, and 6 a¹ is the tap for controlling the supply of gas to the
burner. This tap is secured in any suitable manner to the case 6 of an alarm
clock. is the ordinary handle or lever of the gas tap and d' is a lever attached
to the other end of the plug of the said tap. The lever d'has a bevelled or inclined
projection which when the tap is opened passes the disc e², the lever yielding
for this purpose, and engages with the said disc as shown in Figure 5. This disc
is fixed upon the main arbor f2 of the alarm mechanism, and a slot e³ is formed in
the said disc. When the alarm mechanism is released in the ordinary manner,
the disc e² rotates with the arbor f2 in the direction indicated by the arrows in
Figures 5 and 6; the projection d' on the lever & enters the slot e³ as the disc
rotates and the said lever is disengaged from the disc when the said slot reaches
the position shown in Figure 6 and, being acted upon by the spring g³, closes the
gas tap. By these means I am enabled to regulate the length of time during
which heat is to be applied to the boiler and to ensure the closing of the gas tap
at the proper time
Having thus fully described my said Invention and the manner of performing
the same I wish it understood that I Claim :-
First. The combination, with the moulding or vulcanizing chamber, of an
additional or independent chamber for containing water and supplying steam to a
steam gauge and gas regulator to ensure uniformity in the heat applied to the
apparatus, substantially as set forth.
Second. A box or casing, upon the top of the boiler or heater, provided with a
cover to enclose the clamping screws and prevent the escape of steam, substantially
as set forth.
Third. The combination, with the boiler or heater provided with a suitable
aperture, of the injecting apparatus adapted to be inserted in the said aperture and
secured to the flask, substantially as set forth
Fourth. The flask provided with a thermometer arranged in combination with
the glass window, substantially as set forth, so that when the flask is inside of the
boiler the temperature within the flask can be ascertained at any time.
Fifth. In the injecting apparatus, the combination of the barrel g, the piston h
and the screw i, all constructed and arranged to be operated substantially as, and
for the purpose, set forth.
Sixth. The combination, with the tap for controlling the supply of gas to the
burner, of a lever fixed to the plug of the said tap and acted upon by a spring, an
alarm clock and a device connected therewith for retaining the said lever and
releasing the same when the alarm mechanism operates, all substantially as, and
for the purpose, set forth.
In witness whereof I the said John Hutchens Gartrell have hereunto set my
hand and seal this Fifth day of February in the year of our Lord One*
thousand eight hundred and eighty three.
JOHN. HUTCHENS. GARTRELL. (L.S.)