554. Pelitjean, T. March 5.
Flattening; shaping; moulding. Relates to the manufacture of plane or curved sheet glass, cylinders, "oval cylinders" lenses, convex mirrors or reflectors, glassware, &c. For sheet glass, a bulb or cylinder is prepared, and in the same process or working is compressed between two oppositely rotating discs, so that, by means of the imprisoned air, the glass is flattened and two sheets are formed. The discs B, B1, Fig. 2, are carried by means of discs Q on belt-driven shafts M, M1 supported in sliding heads P, P1,
which can be made to approach each other by means of a right and left
handed screw T operated by bevel gearing G, H from a hand-wheel D. As
the bulb or cylinder is compressed, the glass worker stops the orifice
of the blow-pipe with his thumb, by means of which a high pressure can
be obtained, capable of easy regulation. Circular sheets of glass are
produced by compressing bulbs. To obtain "oval cylinders," the rotary
discs are replaced by rectangular plates having a vertical or
horizontal motion. The discs are made of metal, stone, clay, wood, or
carbon; if wood is used, it is treated with a solution of organic
substances, to prevent scorching and wear and tear. Metal discs are
prepared by coating a plate of glass with gold, silver, or platinum, as
described in Specification No, 1681, A.D. 1855, [Abridgment Class Ornamenting],
and subsequently with copper by electrodeposition, the glass being
afterwards removed. Preferably, however, carbon discs are used. The
carbon is prepared by heating and vaporizing wood tar, and mixing the
pulverized powder obtained therefrom with pulverized charcoal or gas
carbon. From this mixture, the discs are obtained by packing and
compressing it into circular metal boxes, which are closed by covers
and then subjected to varying temperatures in an oven for two days or
more. By these means, carbon in one piece without a crack is obtained.
The discs B, B1 are attached to the discs Q by melted
bitumen, and are fitted and levelled when in place, as shown, by means
of a plate of glass, unpolished on both sides, which is reciprocated
between the oppositely - rotating discs. Large lenses and convex
mirrors or reflectors are obtained by replacing the plane discs by
concave discs; the lenses are filled with a solution of sulphate of
zinc or other solution. Cylindrical moulds for the manufacture of glass
wares are formed of iron or zinc, in two parts, which are hinged
together to open and close, and are provided with handles. Linings of
the specially prepared carbon, formed by turning in a lathe, are then
fitted to the moulds. The blocks in which the preliminary bulb is blown
are made from the same carbon material, and are turned and polished.
|