Improvements in the Manufacture of Glass or Crystal Bulbs, and in Means used therefor.
Year: 1898

page_text: Date of Application, 30th July, 1898-Accepted, 22nd Oct., 1898
COMPLEIE DIECIFICATION.
Improvements in the Manufacture of Glass or Crystal Bulbs, and in
Means used therefor.
1, FERDINAND FANTA, of 97, Queen Victoria Street, London, E.C., Consulting
Engineer, do hereby declare the nature of this invention and in what manner the
sauno is to be performed to be particularly described and ascertained in and by
the following statement: -
This invention relates to the manufacture of that class of glass bulbs, in which
a part is intended to be used for the purpose of allowing the rays of light to freely
emerge from the bulb, whereas another portion of the said bulb is intended to
be used for the purpose of either converging diverging, or reflecting, the said light;
and this more especially, for bulbs used for incandescent electric lamps, wherein
it is essential that the vacuum produced, should be maintained to a high degree;
and this invention consists of an improved process of manufacture, and means
for carrying the same into effect, whereby a combined, welded, part-transparent
and reflecting, globe is produced, of precise, definite and unusual configuration,
whilst the resistance, which it is essential that the glass bulb should offer to the
outer atmospheric pressure, is not impaired.
These desiderata are all the. more difficult to attain in the case of a reflector
lamp, since it is essential that the outer diameter of the reflecting surface, should
be as large as possible, and also that the surfaces of the reflecting surface and of
the clear part of the bulb, be, respectively, as nearly as possible in such relative
positions, as to allow the direct rays, as well as the reflected rays, to pass through
the clear portion of the bulb at right angles, in respect to the surface of the latter,
as set forth in the Specification of Letters Patent No. 23111 dated 3rd Dec. 1895.
In carrying out the said invention, and in order to overcome the practical
difficulties referred to above, a special way of treating the glass, both for the
clear and for the reflecting portion. becomes necessary; especially so, since the
outer edge of the reflector, should in every case, form a perfectly straight line,
and be maintained throughout, within a plane, at right angles to the axis of the
diverging, diffusing, or reflecting surfaces, as the case may be. In order to make
this part of the bulb as regular in thickness as possible, I find it necessary to
treat each portion of the bulb separately; and to treat more especially that portion
which it is intended to use as a reflecting surface, so as to give it the accurate
configuration which experience has proved to be most appropriate.
The process of manufacture described herein, provides for means of moulding
such portion during the blowing process, and at the same time, means of annealing
the joint, which it thus becomes necessary in the process to make, between the
clear, and the reflecting portion, of the bulb.
In order to carry this process of manufacure out, it is necessary to have two
separates' masses of glass ready in a molten state; and I therefore, provide two
furnaces, which may conveniently be heated by a set of burners supplied with
generator gas from a common source; or better still, I use a furnace heated as

page_text: referred to above, in which two distinct pots or basins are provided, wherein the
two classes of glass or crystal are being melted, one being clear and the other
sufficiently opaque to act as a reflector.
It is essential that the compositions of the two crystals be of the same nature,
the glass or crystal used for the reflecting portion being rendered opal or coloured
by the addition of arsenic, or other suitable material, as the case may be.
find that the kind of glass known as "crystal" is more suitable than ordinary
glass for the annealing process.
And in order that this invention may be the better understood I now proceed
to describe the same with reference to the drawings hereto annexed and to letters
and figures marked thereon.
Figures 1, 2, 3, 4, 5 and 6 show a composite globe in the different stages of
manufacture with appropriate tools for such manufacture and
Figure 7 is a section through the heated mould closed for the last operation,
& Fig. 8 is a plan of the same open.
Having the two metals in a molten state and as fluid as possible in the two
crucibles or furnaces, the workman first dips his blow pipe into the opal crystal,
and collects at the end of the same, in the usual way, an appropriate quantity
of opal or opaque molten metal, the quantity of which can either be gauged or
left for him to determine by practice, he then blows same into the shape of an
oblong bulb, the outer form of which is determined by a bent iron C Figure 1
provided at its upper extremity with a fork-like extension B', (at right angles
with such rod,) which rests on a ring B fixed on the blow pipe A, thus deter-
mining, once and for all, the size of this original bulb, and enabling the workman
to cut off with the usual scissors, such superfluous quantity of crystal if any,
which may protrude.
Having done this, the bulb in the state as described, is introduced into the
furnace, so as to raise its temperature, when it is taken out again and pierced at
the end by means of a spike or rod T as shown in Figure 2, the object of which
is to pierce the bottom of the bulb and thereafter by the use of a turned up
forming tool I Figure 2 to form the edge of the opening as a groove or rabbet, to
hold the added metal as hereinafter described, this being necessary for securing
a joint with, the clear crystal. The bulb is now again put into the furnace, and
kept above the molten metal therein, and on withdrawing same an appropriate
quantity of clear crystal is joined on to it by a second workman, whereby a solid
obturating piece is added on to the first part of the bulb as in Figure 3, and is
seized in position by the groove or rabbit formed on the edges of the lower
aperture as made by the preceding handling. The whole being in this state is
placed into a third tool-rod E, which extends over the joint as shown in Figure 4,
the workman blowing through the blow pipe and causing the combined bulb
to take the shape as shown in Figure 4. The joint is thus made and the outer
surface of the bulb kept smooth.
The remainder of the operation consists in gradually bringing the bulb to its
final form, and this obtained by 3 consecutive operations, similar to those described
before, by means of special bent fool rods F and G Figures 5 and 6, whereby the
said bulb gradually takes the shapes shown in Figures 5 and 6 respectively. In
the case of the shaping tools F and G, however, the tool is hollow in the form
of a small tube which extends up to the points F1 and G¹ respectively, and the
inner side of that part of the tube which faces the crystal, is provided in that part
only with small holes. In this way the workman blowing through the blow
pipe A and simultaneously through the tubes F and G respectively, cools the upper
part of the bulb, thus preventing same from being affected by the inner pressure
of the blast and consequently prevents the upper part of the shape of the bulb
from being altered, and by this means the whole of the pressure acts on the
middle and lower part of the bulb which has yet to be extended.
It is essential that the bulb be reheated by insertion in the furnace after each
blowing, that is, between the change of shaping tools.

page_text: At this stage, the bulb has practically taken the shape which it is desired to
give it, but in order to make the same absolutely uniform, the bulb is heated a
last time, and placed, on its withdrawal from the furnace, into a hinged hollow
cast iron mould G, Figures 7 & 8 made of two pieces, and provided with hinges R,
whilst one of the parts has fixed on its upper end, a vertical support H with a fork-
shape extension at right angles, the height of which is so calculated as to allow
the guiding ring B of the blow pipe A to rest on same, when the bulb is in its
right position in the mould. The mould is closed up as soon as the bulb is
inserted, the blow pipe whilst the workman blows into the same, being turned
round by hand several times to ensure homogenity.
The lower part of this mould is provided with a broad flange K to give it steadi-
ness, and each half of the mould is provided with a set of Bunsen burners L L',
air being admitted to them by side orifices, and the heat from which is allowed
to go through vertical channels M M all round the mould for the purpose of
keeping the whole of the mould at a uniform and comparatively high temperature..
On withdrawing the bulb from the mould, the bull is finished, and the same
process can be gone through with another quantity of metal, but it will be under-
stood from the above description of manufacture, that several bulbs can be
treated almost simultaneously with the same set of tools, one being always one
or two stages in advance of the other.
It is obvious that the same process of manufacture will apply when the upper
bulb is of clear glass and an opaque or opal surface is added afterwards to form
an inverted reflecting lamp.
Having now particularly describxxl and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what
I claim is:
-
1st. The process and means of manufacture of bulbs or globes of crystal or glass
in two parts, of diverse characters or transparency, the welding or joining of such
parts in one complete globe, and the annealing and precise shaping of the same
for the purpose set forth, substantially as described.
2nd. In bulbs made of two parts as claimed in Claim 1 blowing the first metal
separately, piercing the bottom of the same, shaping the edge of the aperture to
obtain a uniform line of edge, and to form a rabbet or locking groove therein,
as and for the purpose, substantially as described.
3rd. In the manufacture of glass or crystal bulbs, the construction and use of
solid shaping tools adapted by a fork and a washer upon the blow pipe, and by
their conformation, to gauge and determine the bulk of metal and its ultimate.
conformation as a globe, substantially as and for the purpose described.
4th. In the manufacture of glass or crystal bulbs the construction and use of
hollow shaping tools guided as to the blowing tube, and pierced with les at
specific points to permit air to be blown on determined parts of the globe, to cool
same during manufacture, substantially as and for the purpose described.
öth. In the manufacture of glass or crystal bulbs, the construction and use of
the hinged finishing mould, with guide for the blow pipe, and internal heating
appliances, substantially as set forth and described.
Dated this 30th day of July 1898.
4
FELL & JAMES,
1, Queen Victoria Street, London, E.C.,
Agents for the Applicant.