Improvements in or relating to the Grinding and Polishing of Glass.
Year: 1893

page_text: Date of Application, 4th Oct., 1893-Accepted, 16th Dec.. 1893
Improvements in or relating to the Grinding and Polishing of
Glass.
A communication from THEOPHILE HAUT, of Teumont (Nord), France,
Engineer.
I, ALFRED JULIUS BOULT, of 323 High Holborn in the County of Middlesex,
Chartered Patent Agent, 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 :—
The work of smooth-grinding and polishing glass has, for many years past, been
done on round metallic tables called platforms, varying in diameter between
5, 6 and 7 metres.
Experience has led to the result that both these processes are carried out
uninterruptedly on one and the same table, to which the plate of glass is affixed,
i.e. that after the table has remained a certain time under the smooth-grinding
apparatus, it is transferred to the polishing apparatus, where the operation is
completed and the final polish applied.
With a view to making the tables transferable it has been found necessary to fit
them with travelling wheels mounted on axles, and also to provide for their easy
separation from the vertical shaft on which they are kept in suspension and which
imparts to them rotary motion during the grinding and polishing.
For the purpose of dismounting the platform-table from its vertical shaft, various
mechanical devices have hitherto been employed, but without satisfactory results in
practice owing to their slow action and the consequent loss of time.
The chief subject of the invention lies in the employment of hydraulic pressure
for working the platform-tables in smooth-grinding and polishing glass.
This improved mode of working consists in the elevation of the platform-tables
by hydraulic pressure to the necessary height or working level, and in dismounting
from them the travelling wheels on which they are transported by rail from place
to place; further also, on the completion of that stage of the process, in the use of
hydraulic pressure to lower the platform-tables and replace them on the wheels
which carry them on the rails. The vertical shaft being then detached, the plat-
form-table is removed to the polishing apparatus or vice versa to the smooth grinding
apparatus, as the case may be.
The application and use of hydraulic pressure in the working of such platform-
tables in glass-finishing is shown on various different scales in the four sheets of
accompanying drawings, wherein ;-
1. (Sheets 1 and 2), Figure 1 is a vertical section of the smooth-grinding
apparatus complete ;
Figure 2 a cross section of the same, and
Figure 3 a plan view.
II. (Sheets 3 and 4), Figure 1 is a vertical section of the polishing apparatus ;
Figure 2 a cross section, and
Figure 3 a plan view of the same.
Figure 4 is a diagram showing the arrangement of the polishers of which there
may be more or less than the number shown.
In order to facilitate the explanation of the application and use of hydraulic
pressure for the raising and lowering of platform-tables, in the two machines or
apparatus for smooth-grinding and for polishing sheets or plates of glass, it is
necessary to describe the construction of these latter.
The platform-table properly so-called is shown at A, Figure 1 Sheet 1.
This table is circular, made of cast iron, and carries, on its upper surface, a

page_text: sheet-iron plate to receive the glass that is to be ground and polished; and, on its
lower surface, four axles and four wheels, for transport on the rails a and b. The
table is plane-bedded on a circular zone or ring BC; and by means of this annular
bearing-surface it rests upon a mushroom cross-head D, also truly plane-bedded,
which is keyed on the vertical shaft E. A flanged border on the under side of A,
round the periphery of the annular bearing, prevents displacement of the table from
its cross-head during the movement of rotation. The vertical shaft E rests in a
step-bearing F which serves as a guide for its lower extremity while it rotates ;
and its upper part is guided by a cross girder G the ends of which are carried by
the foundation walls of the structure.
The vertical shaft is caused to rotate by means of bevel-gear, wheel H and
pinion I, horizontal shaft J, and fast and loose pulleys K and L, while the
engaging and disengaging gear M enables the apparatus to be started and stopped
at will.
The step-bearing F is carried by a hydraulic piston-head or plunger N which
moves up and down within its cylinder O according as the water-pressure is
admitted to or cut off from the cylinder; but when the plunger has attained its
highest point, instead of its being kept there by hydraulic pressure, two studs or
tappet-rods n and n' are interposed between the flange of the plunger-head and the
top of the cylinder, so as to take the entire weight off the ram.
For this purpose, the two tappet rods n and n' are guided by a double bracket m
and fixed guides m¹ on the cylinder itself; and they are coupled together by a
cross-piece centrally acted upon by a connecting rod q¹ fitted at its other end
with a rack and moved to and fro by a spur-pinion q fixed on a vertical rod r
carried above-ground to a suitable height and there operated by a hand-wheel r¹.
For the admission of water-pressure to the ram-cylinder O, this latter is connected
by a line of pipes with an accumulator located at some convenient part of the works.
The service-pressure pipe is shown at P, in Figure 2, and at Pin Figure 3, and
communicates with a main Q which may supply several machines from the same.
accumulator. A screw-down valve R operated from above-ground by hand-wheel
and upright rod regulates the admission and cut-off of the water pressure at will.
For the purpose of withdrawing the spent water from the cylinder O, this latter
is also provided with an outlet and second line of pipes discharging into a suitable
reservoir, conveniently placed, whence the water can be pumped up again for re-use.
This discharge pipe is shown at S in Figure 2 and S' in Figure 3, leading to a
main-out-fall pipe T. The withdrawal or evacuation of the water of pressure from
the cylinder, and the stoppage thereof are regulated similarly as above described
by a screw down valve R³ operated from above-ground by the hand-wheel and
spindle pl.
The time and manner of the raising and lowering of the platform have now to
be described.
In Figure 1, Sheet 1, the table A is in position and ready to receive the
movement of rotation during the process of smooth-grinding the glass sheets or
plates.
For this purpose the grinding discs U U' are to be lowered into position; these
discs are of wood and carry on their under surfaces plates of crude cast iron which
rub lightly on the glass, with the aid and intervention of coarse sand and water.
So soon as contact takes place the discs also begin to revolve, owing to the rotary
motion of the table; and they are guided and suspended by a cross-bar X and
vertical shaft Y in an iron framing shown at V and V₁ respectively in
Figures and 2.
Between the iron I-girders of the framing, the upright shafts are held and
guided by stuffing boxes in traverses, and they are fitted with suspensory caps and
collars at their upper extremities, so that they may be raised and lowered by the
operation of the forked arm Z and lever-system W, with pivotted bearings, actuated
by the connecting-rod W₁ and screw-regulator W".
In due proportion to the progress of the process, the discs are gradually lowered

page_text: towards the table, by turning the wheel-handle of the regulator W₁, so that the
contact between the disc and the table becomes closer and closer until the operation
is completed, when the discs are raised and the revolution of the table is arrested.
Then the hydraulic pressure is turned on to the ram or plunger N, by opening
the screw-down valve R until the vertical shaft E and the table A are counter-
balanced, which enables the stops n and n¹ to be released, by a movement of
withdrawal effected by turning the hand-wheel and spindler which actuate
them; that being done, the hydraulic pressure is insensibly relaxed and the cylinder
evacuated, by opening the screw-down valve R' and closing R, whereby the ram
and its load are gently lowered, until, at a given moment the descent of the table
itself is arrested by its wheels coming to rest on the rails on which it runs.
vertical shaft however continuing its downward movement, leaves the table, and
comes finally to rest when the ram reaches its lowest point at the bottom of the
cylinder. The table is now completely liberated and may be transferred to the
polishing apparatus.
The
The polishing apparatus is shown on Sheets 3 and 4 of the accompanying drawings,
Figures 1, 2 and 3.
The distribution of the hydraulic pressure is identically the same as that for the
smooth-grinding apparatus.
When the platform-table after leaving the grinding machine is brought along the
rails into proper position under the polishing machine the rain piston or plunger N
is as last stated, at the bottom of the cylinder; the screw-down valve R is then
slowly opened (as before) to admit the pressure below the piston, which itself, and
with it the vertical shaft and mushroom cross-head, begins to rise whereby the
latter is brought to bear upon the table and raises it until it is brought up to the
working level of the apparatus. At this moment the tappets, studs or stops n n¹
are set in motion forwards (likewise as before) until they interpose between the
cylinder-head and the flange or collar of the plunger. This being done, the
hydraulic pressure is released and taken off by opening the valve R' and closing R,
when the polishing process may be begun.
This apparatus shown in Figures 1, 2 and 3, Sheets 3 and 4, of the accompanying
drawings, is composed of two bracket-plummerblocks A A' each guiding two
vertical shafts B B₁, B¹ B'₁, carrying keyed on to their upper ends, four crank-
discs CC, CC. These shafts are centrally guided by two traverses D D' and
supported at their lower ends by step-bearings E E¹. Between each pair of the
vertical shafts B B₁, B B', there are intermediate counter-shaft F F₁ all being
connected by spur-wheels G G₁ G, and G' G, G₁₂; while in addition the bevel-
gear wheels H and H¹ are keyed on to the vertical shafts B B¹.
The motive power is communicated by means of a horizontal shaft I, carrying
fast and loose pulleys J J' and having keyed on to it the two bevel-gear
wheels K and K engaging with and driving the bevel-wheels, H H', and thus causing
the rotation of the vertical shafts B B as well as of F F and B' B₁₁; and by
reason of this geared connection the four crank-discs C C₁ C' C₁, rotate in the same
direction. The crank pins of the discs are connected together in pairs and set in
motion two oscillating working beams which carry the polishers these being cast-iron
plates, covered with felt, suspended from the bearer and free to rotate on a
vertical axis.
1
When the machine is set in motion, the polishers are in contact with the glass
surface on the table and the movement given to them by the oscillating beam is
transmitted to the table which is made to revolve on its vertical axis by the
rubbing friction.
Having now particularly described and ascertained the nature of the said inven-
tion as communicated to me by my foreign correspondent, and in what manner the
same is to be performed I declare that what I claim is ;-
1. In apparatus for smooth-grinding and polishing glass the application and use
of hydraulic pressure in the working of platform-tables by causing such pressure

page_text: to act under the vertical shafts which support such tables to facilitate the shifting
and transporting of such tables and render such operations more easy rapid and
practicable.
2. The combination and arrangement of parts constituting the complete smooth-
grinding apparatus substantially as described and illustrated in Figures 1 to 3
Sheets 1 and 2 of the accompanying drawings.
3. The combination and arrangement of parts constituting the complete polishing
apparatus substantially as described and illustrated in Figures 1 to 3 Sheets 3 and 4
of the accompanying drawings.
Dated this 4th day of October 1893.
W. P. THOMPSON & BOULT
Agents for the Applicant.