Improvements in Muffles for Dental Furnaces.
Year: 1897

page_text: PROVIDIUNAL SPECIFICATION.
Improvements in Muffles for Dental Furnaces.
I, WILLIAM DALL, of 8, Newton Place, Glasgow, Surgeon Dentist, do hereby
declare the nature of this invention to be as follows:-
This invention relates to the muffles of dental furnaces. The muffles are used
for firing porcelain and other material used in the manufacture of artificial teeth
and palates and as a consequence they are required to stand a very intense heat.
Platinum, nickel and other metals have heretofore been used from which to manu-
facture the muffles. Platinum is the most durable but at the same time it is the
most expensive metal to use, whereas nickel although not so durable is com-
paratively cheap and further it has been found generally to answer the purposes
required. Nickel muffles however have not come into general use, owing to the
fact that they are very difficult to make.
My invention has for its object to provide improved methods of manufacture
whereby nickel muffles can be easily and cheaply made.
In carrying out my invention under one method 1 spin the metal into a hollow
cylindrical form and then by means of hydraulic or other pressure or by hammer-
ing or beating force the spun metal into the desired shape upon a mandril or
pattern-block of either metal or wood. The pressing or hammering of the metal
into shape may, as found necessary, be performed in either one or more operations.
The cylinder or blank from which the muffle is made may, if desired, be spun to
an oval or somewhat oval shape in cross section so as to facilitate the subsequent
procedure.
If desired the muffle may be spun into shape direct from a tube or cylinder.
In the case of cylindrical or nearly cylindrical muffles they would be merely
spun into shape.
Under another method I use sheet nickel and work it up to the proper shape
either by hammering, beating or pressure. In this case the meeting ends or
edges of the sheet are made to overlap so as to form a tight lap joint. A back
piece or plate is or may be jointed or otherwise secured to the body of the muffle.
In the case of pot muffles I either spin, press or work them up to the desired
shape and then fit a lining within the pot in any suitable manner such as by
rivetting or otherwise. The lid is made with a downward Hange which is capable
of fitting tight into the space between the lining and the outer wall of the muffle.
The muffle may be made of sac shape with a narrow or reduced opening or
mouth.
In the case of muffles provided with linings the lining may be spun into place
and for this purpose a groove or bead is made in the outer wall of the muffle.
Dated this 23rd day of November 1897.
H. D. FITZPATRICK,
70, Wellington Street, Glasgow, Agent.

page_text: Improvements in Muffles for Dental Furnaces.
I, WILLIAM DALL, of 8, Newton Place, Glasgow, Surgeon Dentist, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:
This invention relates to the muffles of dental furnaces. The muffles are
employed for firing porcelain and other material used in the manufacture of
artificial teeth and palates and as a consequence they are required to stand a very
intense heat. Platinum, nickel, and other metals have heretofore been used from
which to manufacture the muffles. Platinum is the most durable but, at the same
time, it is the most expensive metal to use, whereas nickel, although not so durable,
is comparatively cheap and, further, it has been found generally to answer the
purposes required. Nickel muffles however have not come into general use owing
to the fact that they are very difficult to make.
My invention has for its object to provide improved methods of manufacture
whereby nickle muffles can be easily and cheaply made.
In carrying out my invention, under one method, I spin or stamp the nickel
into a hollow cylindrical form and then by means of hydraulic or other pressure
or by hammering or beating force the spun metal into the desired shape upon a
mandril or pattern block of either metal or wood. The pressing or hammering
of the metal into shape may, as found necessary, he performed in either one or
more operations, and, in the latter case, a series of mandrils would be used. The
cylinder or blank from which the muffle is made may, if desired, be made of an
oval or somewhat oval shape in cross section so as to facilitate the subsequent
procedure.
If desired the muffle may be spun or stamped into shape direct from a tube or
cylinder.
In the case of pot-muffles I either spin, press, or work them up to the desired
shape and then fit a lining within the pot in any suitable manner. The lid is
made with a downward flange which is capable of fitting tight into the space
between the lining and the outer wall of the muffle.
In the case of muffles provided with linings the lining may be spun or pressed
into place and for this purpose a groove or bead is made in the wall of the muffle
and the living.
The muffle may be made of sac shape with a narrow or reduced opening or
mouth.
And in order that my said invention may be properly understood I have here-
unto appended an explanatory sheet of drawings, whereon,
Figs. 1 and 1, 2 and 24, 3 and 3, illustrate in longitudinal section and front
view respectively the process of manufacturing a nickel muffle under one method.
Figs. 4 and 4 illustrate in longitudinal section and front view respectively
another form of nickel muffle.
Figs. 5 and 5 illustrate in longitudinal section and front view respectively
another form of nickel muffle.
Fig. 6 is a plan view and Fig. 7 a section of a nickel pot-muffle.
On the drawings the same reference letters wherever repeated indicate the same
or similar parts.
The nickel muffle, as shown at Figs. 1 to 3, is manufactured as follows:- —The
sheet nickel is first spun or stamped into a hollow cylindrical form, such as shown

page_text: at a Figs. 1 and 1', and this cylinder, which is made with a bottom b, constitutes
a blank from which the complete muffle Figs. 3 and 3* is made.
After the nickel
has been made into the shape shown at Figs. 1 and 1 it is softened by annealing.
under heat, and quenched in water. The now softened blank is gradually worked
up, on a series of mandrils or blocks, until it assumes the shape shown at Figs. 2
and 2. The muffle is finally completed by turning over the flange a (Figs. 3
and 3) at its front end or mouth which can be done by hammering or by pressure
in a suitable stamping press. It will be seen that the muffle. as completed, is of
a D shape with a flattened floor a¹. The front flange is for the purpose of enabling
the muffle to be properly fitted within the casing or wall of the furnace.
Instead of making the muffle in the manner herein before described with
reference to Figs. 1 to 3 it may be first made into the cylindrical form shown
at Figs. 1 and 1 and then the closed end 6 be cut off. The resulting tube, open
at both ends, can now be shaped on a mandril to the oval form shown at c. Figs. 4
and 4. This tube has. or may have, a front flauge c, or both front and back
flanges e, made upon it in the same manner as the flange a of the first muffle
and for the same purpose.
The muffle can be made up direct from a piece of seamless nickel tube which is
cut to the proper length. If the muffle is to be of oval shape the tube can be
pressed by dies or clamps or hammered upon a mandril to the desired oval form.
Should it be desired, with such a muffle, to have a back on it then a flange is
made at the back end and a disc d jointed over it by a lap joint as shown in the
muffled Figs. 5 and 5. The lap joint is well hammered or pressed down so as to
prevent the ingress of gas from the furnace to the goods being fired. The
muffle has, preferably, a front flange .
Figs. 6 and 7 show a form of pot-muffle similar to that described in my prior
Patent No. 6128 of 1896 but made entirely of sheet nickel. The body of the
muffle is spun, pressed, or worked up to the shape shown at Fig. 7 and then a ring
shaped lining f is inserted into it. This lining is very carefully spun or turned
up to a shape that will exactly fit the interior of the muffle body so that, when
it is inserted in place, it will not readily fall out. In order to insure that it will
not fall out internal grooved heads may be subsequently made in both the
body e and the lining as shown clearly Fig. 7. The lining f is also made with
a part g set back slightly so as to leave an annular space between it and the in-
ner face of the wall of the body e for the reception of the downwardly extending
flange or rim e³ of the lid c'. This lid is stamped or spun to the shape shown and
is provided with a central projection 2 which constitutes a knob whereby the lid
can be lifted. If so desired instead of the projection ² a knob or handle may
be secured to the lid.
The lugs made on the body e are for the purpose of supporting the muffle in
the furnace in the same manner as in my prior patent aforesaid.
If desired lateral tubular extensions may be made at opposite sides of the
muffle as indicated in dotted lines Fig. 7 for the purpose of inspecting the work
whilst being heated. These extensions are flanged at their inner ends and fitted
in holes in the body of the muffle, being held in place by the ring This ring
would be made with holes in it corresponding to the openings of the extensions.
Where seamless oval nickel tubes can be obtained they can be used in the manu-
facture of the muffles Figs. 4 to 5^.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed I declare that what I
consider novel and desire to claim is:-
1. A nickel muffle for dental furnaces which is made by first spinning or
stamping the metal into a hollow cylindrical form and then, by means of hy-
draulic or other pressure or by hammering or beating, forcing the metal into
the desired shape upon a mandril or pattern block or a series of mandrils or
pattern blocks, substantially as hereinbefore set forth.

page_text: 2. A nickel muffle made substantially in the manner herein before described with
reference to Figs. 4 and 4 and also with reference to Figs. 5 and 5 of the draw-
ings annexed.
3. The nickel pot-muffle made substantially as hereinbefore described with
reference to Figs. 6 and 7 of the drawings annexed.
1000
H. D. FITZPATRICK,
100, Wellington Street, Glasgow, Agent.