Cylinders, Hollow Ware, and Analogous Articles.
Year: 1886

page_text: Cylinders, Hollow Ware, and Analogous Articles.
I MORITZ SCHREIBER, Director of Glassworks at Fürstenberg in the German
Empire 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 the manufacture of tubes cylinders and other hollow or similar articles of
glass it is found difficult to protect them from unequal cooling or annealing, hence
there generally arise certain tensions or strains in the material which subsequently
induce cracking or fracture of the article in grinding or upon sudden changes of
temperature, a similar result may also be caused by unequal thicknesses in the
walls of the article. Even when the article has been properly annealed it some-
times happens that in a subsequent stage of manufacture the internal equilibrium
of the molecules is disturbed and the annealing effect is neutralized or destroyed as
for example in the melting of the ground edges of lamp glasses to remove the
roughness caused by grinding or in burning in a brand or trade mark.
This Invention has for its object to prevent the loss by cracking or breaking of
glass tubes cylinders and other hollow articles arising from unequal cooling or
annealing or from unequal thicknesses as hereinbefore described, and these
Improvements consist in applying enamel (Glasschmelzfluss) corresponding to the
hardness of the glass and alone or combined with colour to the article, which is
mounted upon an iron mandrel or other suitable core and subjected to heat until
the enamel is entirely melted or the article is properly softened. The article is
then removed from the mandril or core and is rapidly air-cooled. In some cases
the use of the mandrel or core may be dispensed with.
Lamp chimnies, gauge glasses and the like articles which have ground ends or
edges are ground before being mounted upon the mandril or core and heated, and
they may be marked with the enamel (Glasschmelzfluss) by means of an india-.
rubber stamp. They are then introduced singly into a muffle or suitable furnace
and are continuously rotated until the enamel has entirely melted or the articles
are uniformly and properly softened by the heat. The articles are then removed
from the mandrel or core and are exposed to the open air or to the air in a well
ventilated room so as to ensure rapid cooling, care being taken to stand them on
their ends and not to lay them on their sides.

page_text: When it is desired to anneal large quantities of hollow glass ware such as lamp
chimnies and the like articles they are placed in a muffle which is then introduced
into a furnace. As soon as the articles have been heated to the required tem-
perature the muffle is removed from the furnace and opened on both sides to ensure
rapid cooling.
If the enamel marking is well melted down it is evidence that the articles have
been heated to the required degree. Besides producing articles possessing great
powers of resistance to sudden changes of temperature by these Improvements
the ground ends are fused, while the enamel mark affords a certificate that the
annealing has been properly. effected.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed I declare that what
I claim is ;-
°
The method of annealing glass tubes cylinders hollow ware and analogous
articles consisting in marking the article with a suitable enamel and heating it
uniformly until the enamel melts and in then removing the article from the source
of heat and rapidly air cooling it, substantially as herein before set forth and
described.