IMPROVEMENTS IN APPARATUS FOR MOULDING ARTICLES OF CELLULOID, INDIA-RUBBER, AND SIMILAR MATERIALS, CHIEFLY DESIGNED FOR THE MANUFACTURE OF DENTAL PLATES."
Year: 1879

page_text: LETTERS PATENT to John Hutchens Gartrell, of Penzance, in the County of
Cornwall, for the Invention of "IMPROVEMENTS IN APPARATUS FOR MOULDING
ARTICLES OF CELLULOID, INDIA-RUBBER, AND SIMILAR MATERIALS, CHIEFLY
DESIGNED FOR THE MANUFACTURE OF DENTAL PLATES."
PROVISIONAL SPECIFICATION left by the said John Hutchens Gartrell at
the Office of the Commissioners of Patents on the 13th December 1879.
JOHN HUTCHENS GARTRELL, of Penzance, in the County of Cornwall.
"IMPROVEMENTS IN APPARATUS FOR MOULDING ARTICLES OF CELLULOID,
INDIA-RUBBER,
AND SIMILAR MATERIALS, CHIEFLY DESIGNED FOR THE
MANUFACTURE OF DENTAL PLATES."
My Invention relates to improved apparatus for moulding celluloid, vulcanite,
and the like into any desired form, and is chiefly designed to afford the means for
advantageously manufacturing plates or bases for artificial teeth.
In the apparatus to which iny Invention relates the celluloid or other material
is injected or forced from a boiler or heater into the flask containing the plaster of
Paris mould after the said flask is closed and secured in the apparatus, and when
properly filled with the celluloid or other material the said flask is removed and
kept under pressure while cooling.
I am aware that apparatus for injecting or forcing celluloid or other materials
into flasks or moulds used in the manufacture of dental plates has already been
used, but such apparatus has not proved satisfactory, and therefore its use is now
abandoned, although the method of filling the flasks by injection is acknowledged
to possess many advantages over the ordinary method of filling the flasks with a
mass of the celluloid, then closing them, placing them in the boiler and subjecting
them to pressure by forcing the two parts of the flask together.
My improvements comprise the following novel features, viz. :-
Enclosing the injecting cylinder in a boiler which is preferably heated by gas
and provided with an instrument forming a combined pressure gauge and regulator.
This instrument is described in the Specification of my former Letters Patent,
dated 13th December 1878, No. 5112, and controls the supply of gas to the burner
so that the heating of the boiler is thereby automatically regulated; but if desired
the said boiler may be otherwise heated. This boiler is also provided with a suitable

page_text: funnel and tap for supplying the same with water, and it has a test cock for
ascertaining the quantity of water therein By having the said cylinder enclosed
in a boiler in which the steam is generated, and which is provided with means for
regulating the pressure or maintaining any desired pressure therein, I am enabled
to maintain the precise degree of heat required for keeping the celluloid or india
rubber in a properly plastic condition. The piston or plunger of the said cylinder
may be operated by a screw or a lever, or by any other means whereby the pressure
required for forcing the plastic material into the flask may be conveniently applied
to the said piston.
Another novel feature of my Invention consists in providing in connection with
the said boiler a separate steam tight-chamber for the reception of the flask into
which the celluloid or other plastic material is to be injected. This chamber is
fitted to the boiler by inserting its edge in a groove or channel formed in the side
of the boiler and provided with any suitable packing to render the joint steam-
tight. The said chamber is held in place by a screw clamp, which allows it to be
readily removed and replaced. The boiler is provided with a valve or cock for
admitting steam to this chamber when required. This chamber affords the means
for admitting steam to hoat the flask when the culluloid or other plastic material is
being forced therein, and obviates the necessity for allowing the steam to have
access to the said flask for a sufficiently long time before the introduction of the
plastic material to injure the plaster mould and thereby disarrange the teeth.
The two parts or halves of the flask are formed with screw threaded projections
upon which nuts are screwed to hold them together, and at one side of the said
flask the same is secured in the end of the cylinder by means of the screwed
projection. The said flask has its two halves further secured together by a scrow-
clamp placed over the same, and each half of the said clamp has a loose cover
formed with tongues arranged to project above and below a rim or flange on the
body of the flask. Slots are formed through this rim, and the inner tongues are
passed through these slots, the cover being then partially turned so that the said
tongues engage with the rim and hold the cover securely thereon. This arrange-
ment affords convenient means for removing the plates from the flask and freeing
them from the plaster of Paris.
I may adapt my improved injecting apparatus to the vulcanizer or boiler des-
cribed in my said former Specification, or to similar vulcanizers. For this purpose
I provide the vulcanizer with a cover which has a long neck fitted with a stuffing
box through which passes the stem of a screw for operating the piston. The said
cover has on its inner side two lugs or projections through which I pass screw pins
whose ends form pivots or bearings for flanges on the sides of the injecting cylinder.
The said lugs are also provided with projections above the said flanges. The flask
is secured to the cylinder as herein before described and occupies the lower portion
of the said vulcanizer.
The said cover may be readily removed and replaced to permit the flasks to be
placed in and taken out of the vulcanizer, and the said cylinder may be removed
from its supports and replaced by another cylinder when necessary.

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 12th
June 1880.
IN
JOHN HUTCHENS GARTRELL, of Penzance, in the County of Cornwall.
"IMPROVEMENTS APPARATUS FOR MOULDING ARTICLES OF CELLULOID,
AND SIMILAR MATERIALS, CHIEFLY DESIGNED FOR
MANUFACTURE OF DENTAL PLATES."
INDIA-RUBBER,
THE
My Invention relates to improved apparatus for moulding under pressure celluloid,
vulcanite, and similar plastic materials, that is to say, materials capable of being
rendered plastic by heat, and for giving to such materials any desired form; the
said Invention is chiefly designed to afford the means for advantageously manu-
facturing plates or bases for artificial teeth. These culluloid or other plates are
made in a mould which is usually formed of plaster of Paris, and produced by
placing a wax model of the plate in a metal box or flask and surrounding the said
model with the plaster, the wax being then melted out of the mould and replaced
by the celluloid or other material of which the plates are formed.
In the kind or class of apparatus to which my 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 tightly closed and placed in the boiler
or heater, and when the mould is properly filled with the celluloid or other plastic
material the flask is removed from the heater and allowed to cool under pressure.
When dental rubber is used for forming the plates they may be vulcanized without
removing the mould from the boiler or heater.
I am aware that apparatus for injecting or forcing celluloid or similar plastic
material into moulds for the manufacture of dental plates has already been used to
a limited extent, but such apparatus has not proved satisfactory, and its use has
been entirely, or almost entirely, discontinued; although this method, that is to
say, the filling of the flasks or moulds by injecting the celluloid or other material
while in a plastic or semi-fluid condition into the same is acknowledged to possess
many advantages over the ordinary method wherein the moulds are first filled with
a mass of celluloid, then closed and placed in the boiler and subjected to pressure
to cause the celluloid or other material to properly fill the mould by forcing or
squeezing the two halves or parts of the same together.
My improvements have for their most important novel feature the enclosing of
the injecting cylinder and the flask containing the mould in a boiler or steam-tight
chamber, so that the celluloid or other plastic material to be injected into the flask
and mould, and after being forced into the latter can be heated to any desired
degree above the boiling point of water (viz., 212° Fahrenheit). The said Invention
also comprises various novel features of construction and arrangement of the parts
of the said apparatus, as hereinafter set forth and as shewn in the accompanying
Drawings, in which,―
Figure 1 is a plan, and
Figure 2 is a side elevation of my improved apparatus.
Figure 3 is a longitudinal vertical section on the line x, x, Figure 1, and
Figure 4 is an end elevation partly in transverse section on the line y, y, Figure 1,
of the said apparatus.
Figure 5 is a central longitudinal section illustrating a modified construction of
the said apparatus.
Figure 6 is a central longitudinal section of another form of my improved
injecting apparatus applied to a boiler or vulcanizer, as hereinafter described.
Figure 7 is a plan or top view of my improved flask employed in the said

page_text: In the two forms or modifications of the said apparatus, shewn in Figures 1 to 5,
a is a stand or base of cast iron or other suitable material; b, b, represent
standards or brackets formed or fixed thereon; c is the boiler; c' is the lamp or
burner for heating the same; d is the cylinder enclosed in the said boiler; e is the
forcing or injecting piston or plunger; f is the screw for operating the latter, the
said screw being fitted to work through a tapped hole in the clamp-frame ƒ¹; g is
a cover placed on the flange c³ of the boiler to enclose the flask h. This cover has
its edge g¹ fitted in an annular groove or channel formed in the face of the flange o³,
and I use any suitable cement or other packing to make the joint between the said
cover and flange properly steam-tight; i is an adjustable clamp-frame provided
with a screw or other suitable device for holding the said cover in place while
permitting it to be readily removed and replaced as required. The clamp frames f¹
and i are adjustably supported on pivot-pins at the top of the brackets b, and may
be turned up or down on these pivots.
It will be observed that the apparatus shewn in Figure 5 differs from that
shown in Figures 1 to 4, in having a partition ; between the steam space of the
boiler and that of the cover, and the said partition is provided with an aperture;¹
which can be opened or closed by the valve k to regulate the admission of steam
from the boiler to the space enclosed within the said cover. The separate steam-
chamber thus formed for containing the flask into which the celluloid or other
plastic material is to be injected forms one of the novel features of my Invention.
This separate steam-tight chamber for containing the flask affords the means for
admitting and excluding steam from the space surrounding the flask as desired,
that is to say, steam may be excluded from this chamber or space while the boiler o
is filled with steam to heat and soften the celluloid or other material placed in the
cylinder, and may be admitted to the said chamber when the operation of forcing
or injecting the same into the mould commences. Moreover, when one mould has
been filled with the celluloid or other material the steam may be confined in the
boiler by closing the valve during the removal of the flask, and the adjusting of
another flask to be filled in a similar manner, the time required for reheating the
boiler being thus saved.
The end d* of the cylinder d projects beyond the boiler c, and is formed with a
screw-thread for holding the flask h in place. A hole c* is made in the boiler for
the reception of a gauge or thermometer. I prefer that the said boiler o should
be provided with the gas-regulating and indicating instrument described in the
Specification of my former Letters Patent, dated 13th December 1878, No. 5112,
which instrument controls the supply of gas to the burner, so that the heating of
the boiler is thereby automatically regulated; but if desired the said boiler may
be used with a thermometer to indicate the heat. The boiler c is also provided
with a hole for supplying the same with water, and it has a test-cock for ascer-
taining the quantity of water therein. By having the said cylinder enclosed in a
steam-tight vessel or boiler in which the steam is generated, and which is provided
with means for regulating the pressure or maintaining any desired pressure therein,
I am enabled to ensure the precise degree of heat required for keeping the celluloid
or india-rubber in a properly plastic condition, and also for vulcanizing the india-
rubber. The piston or plunger of the said cylinder may be operated by a screw, as
shewn, or by a lever or any other means whereby the pressure required for
forcing the plastic material into the flask may be conveniently applied to the said
piston.
I may adapt my improved injecting apparatus to the vulcanizer or boiler described
in my said former Specification, or to similar vulcanizers, as shewn in Figure 6.
For this purpose I provide the vulcanizer or boiler c with a cover c, which has a
long neck o fitted with a stuffing box, through which passes the stem of the screw f
for operating the piston e. In this apparatus the said cover has on its inner side
two lugs or projections c, through which I pass screw-pins c³, whose ends form
pivots or bearings for flanges d' on the sides of the injecting cylinder d. The said
lugs are also provided with projections c³ above the said flanges,

page_text: The flask his secured to the cylinder, as hereinafter described, and occupies the
lower portion of the said vulcanizer. The said cover may be readily removed and
replaced to permit the flasks to be placed in and taken out of the vulcanizer, and
the said cylinder may be removed from its supports or replaced by another cylinder
when necessary.
The two parts or halves h³, h², of the flask h are formed with screw-threaded
projections, which when the two parts of the flask are properly put together form
screw-necks, whereon nuts m are screwed to secure the said two parts in place;
and one of these screw-necks is screwed upon the end of the cylinder & to hold
the flask in connection therewith while the plastic material is injected into the
same. I provide one or both halves of the said flask with a loose cover n formed
with tongues o, arranged to project above a rim or flange h³ on the body of the
flask and with other tongues p to project below the said rim, and it will be observed
that the tongues o and p are not opposite each other. Slots are formed through
this rim. To secure the cover n on the flask the inner tongues pare passed through
these slots, the cover being then partially turned so that the said tongues move
away from the slots and engage with the rim, thereby holding the cover socurely
thereon. This arrangement is more convenient for firmly securing the cover to tho
flask than the ordinary methods of using screw-bolts, pins, or wedges for this
purpose. I provide the cover n with a disc or plate q, which has a screw-stom q¹
passing up through the said cover. By screwing this disc or plate down or inward
when the flask is closed the plaster is compressed and superfluous moisture
expelled.
In commencing to work with my improved apparatus, shewn in Figures 1 to 4,
the flask containing the mould is secured on the end of the cylinder, as shown in
Figure 3; then the cover g is secured in its place on the boiler by means of the
screw-clamp i, i, the boiler having been supplied with the proper quantity of water.
The celluloid or other material is inserted in the rear end of the cylinder d, and tho
clamp frame f' is adjusted in the proper position to permit the piston e to enter
the said cylinder; then the lamp or burner is lighted and steam is generated in the
said boiler. When the celluloid or other material has been reduced by the heat to
a suitably plastic condition it is injected or forced by the said piston into the
flask, and will thereby be caused to fill the space left in the mould by the wax
nodel The pressure of the piston will ensure the proper filling up of the entire
space within the mould so that the celluloid or other plate will be perfectly formed,
and will have the teeth properly embedded and secured therein. Small spaces or
apertures made in the flask permit the plastic material to escape but not till every
portion of the mould has been properly filled with the plastic material. When this
operation is finished the cover g is removed from the boiler, and the flask is
unscrewed from the cylinder and placed on one side to cool, while another flask
may be attached to the cylinder to have the plastic material injected into the same,
or the flask may remain attached to the cylinder and the boiler be used as an
ordinary vulcanizer, as above described.
The operation is substantially the same when either of the other forms or modi-
fications of the said apparatus is used.
Having thus fully described ny said Invention, and shewn how the same may
be conveniently and advantageously carried into practice, I wish it understood that
I am aware of former Letters Patent whose Specifications describe apparatus for
injecting plastic material into moulds for making dental plates, in which apparatus
the injecting cylinder has been surrounded by an open jacket through which steam
is passed, this steam or vapour not being under pressure and therefore obviously
not very effectual as a heating agent; but my Invention is distinct from such
apparatus in respect of the use of steam-tight enclosures for the cylinder and flask,
whereby I am enabled to use steam at any desired pressure and therefore at any
temperature required for effectually heating the celluloid or other material and for
cooking or vulcanizing dental rubber, and I claim, —
First. In an apparatus for manufacturing dental plates or other articles of

page_text: celluloid, india-rubber, or similar material by injecting such material into the mould
the enclosing of the injecting cylinder in a steam-tight chamber or boiler, for the
purpose specified.
Second. In such apparatus the enclosing of the flask or box containing the mould
in the same steam-tight chamber or space as the cylinder or in a separate steam-
tight chamber, for the purpose specified.
Third. The improved apparatus, constructed according to either of the forms or
modifications shewn in Figures 1 to 4, or in Figure 5, or in Figure 6, operating as
above described, for heating the celluloid or other material and injecting the same
into the mould, substantially as above set forth.
Fourth. The improved flask or box provided with the loose cover or covers with
or without the adjustable screw plate or disc therein, substantially as and for the
purposes specified.
In witness whereof, I, the said John Hutchens Gartrell, have hereunto set my
hand and seal, this Ninth day of June, in the year of our Lord One thousand
eight hundred and eighty.