Polishing Plate or Sheet Glass.
Year: 1886

page_text: Date of Application, 29th Oct., 1886.
Complete Left, 29th July, 1887.
Complete Accepted, 30th Aug., 1887.
миргоѵещению III PADRON UT
Polishing Plate or Sheet Glass.
I, EDMUND BROWN, of No. 2 Marine Approach South Shields in the County
of Durham, Manager of Plate Glass Works do hereby declare the nature of this
invention to be as follows:-
This invention consists of constructing the table or bench in such a manner that
when the plates of glass are laid upon the top of it, and the edges made air tight,
a vacuum may be formed by exhausting the air from beneath them to retain them in
position by the pressure of the atmosphere until the operation of grinding, smoothing
or polishing is completed.
The table or bench, instead of being made in the ordinary manner, and the plates
of glass retained in the position with plaster of Paris, is made as follows:-
The body of table or bench can be made, either of wood, iron, steel or any other
suitable metal, or of stone, cement or brick work. The top of the table or bench
which may be of wood, iron, steel or other suitable metal or of stone or cement
is made with a series of grooves or depressions in the face, running either longitu-
dinally or transversely, and preferably terminating a few inches short of each end
and side so as to leave a plain surface for the edges of the plates to lie upon. When
the top of table or bench is made of wood the series of grooves may be formed
by spaces left between strips of wood, or of suitable metal or other material which
may be covered with cotton twill or some other soft material secured with countersunk
screws or bolts, the ends and sides forming plain surfaces by broader strips of the
same material framed with air tight joints at corners, or the grooves may be planed
out of the solid wood.
When the table is made of iron, steel or other metal it may be formed in the same
way by strips framed at sides and ends or by casting the grooves in top surface
or by planing them out. When constructed in stone or cement the grooves can
be formed in the upper course of stones or cut into the cement.
The spaces or grooves communicate with a common air channel, at end of table
if laid longitudinally or at side if transversely, underneath the outer frame into which
air channel is fitted a stop cock or valve which communicates with an air exhausting
nuun

page_text: By another method the top of the table or bench is constructed so as to form
a hollow cavity, or series of cavities, between the upper and under surfaces the upper
surface being perforated with holes or slits through it instead of with grooves. In
this form the top of table will be preferably made of iron, steel or other suitable
metal, preferably in one casting or it may be made in sections or separate parts
or may be of composite construction.
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The plates of glass are laid upon the table or bench so as to cover all the air
grooves or perforations within their area, their edges resting upon the strips or upon
the unperforated surfaces the joints between the plates of glass being luted
and made air tight by means of plaster of Paris or any other suitable cement, the
outer edges of plates being also made air tight in a similar manner and when
the Plaster of Paris or other cement employed has hardened the air is exhausted from
the air spaces or grooves or from the hollow cavity or cavities by means of an
air pump and a vacuum formed which retains the glass upon the table or bench
to allow of it being ground, smoothed or polished by the machinery usually
employed.
Dated th: 0041
1000
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Tables or Benches for Grinding, Smoothing, and
Polishing Plate or Sheet Glass.
I, EDMUND BROWN, of No. 2 Marine Approach, South Shields in the County
of Durham, Manager of Plate Glass Works, 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 :-
This invention consists of constructing the table or bench in such a manner that
when the plates of glass are laid upon the top of it, and the edges made air tight,
a vacuum may be formed by exhausting the air from beneath them to retain them
in position by the pressure of the atmosphere until the operation of grinding,
smoothing or polishing is completed.
From experiments I have made I find that sufficient pressure to hold the plates
in position is obtained by forming cells or cavities in the top of table, as described
in the latter portion of my Provisional Specification, and as this method is readily
applied to existing tables or benches and dispenses to a great extent, or in some cases
entirely, with plaster of Paris or other cement, I propose generally to adopt the
construction which I have shewn on accompanying drawing and which I will now

page_text: describe, it being understood that the drawing and description refer to polishing
tables, but in tables or benches for grinding or smoothing the method is similar,
the sizes or number of the cells or cavities being proportioned to give the required
pressure of the atmosphere to keep the plate or sheet in position, with or without the
assistance of a bed on the table between the cells or cavities or of Plaster of Paris along
the edges.
The top of the table or bench A may be constructed of wood, or of iron, steel
or any other suitable metal, or of cement, slate, stone or brickwork or of a composite
nature, in the surface of table or bench are left or made a series of cells or
cavities B B B which may be made of the same material as the top of table or bench
or may be made of a different material and inserted in top of table. From each
of the outer or side cells or cavities is led a pipe C, which may be made of iron,
copper or any suitable metal, which terminates at the outer edge of table, or air
channels may be formed in the material of table. On the end of each pipe or channel
is fixed a stop cock or valve D all communicating with a main pipe
to which can
be attached, a movable flexible pipe F communicating with an air exhausting pump
which is placed in the most convenient position for the purpose. The middle series
of cells or cavities communicate with each other by means of pipes let into each cell
or cavity or by channels from one to another which pipes or channels terminate
at one end of table or bench and on the end is fixed a similar stopcock or valve
as at sides, the series of cells or cavities are thus all exhausted at one time though
it is not necessary they should be so, but if more convenient could be exhausted
separately, or from both ends, by attaching the flexible pipe, communicating with
the air exhausting pump.
The side cells or cavities are exhausted separately, as it is usual in grinding,
smoothing or polishing of plate or sheet glass to place small plates or sheets of glass
at one or both sides of the tables or benches, the middle of table or bench being
usually covered with large plates or sheets of glass as shown in drawing, on which
they are indicated by dotted lines.
Around each cell or cavity is placed a piece of very soft india-rubber, or other soft
material (the former being preferred) about 2 inches wide, these pieces of indiarubber
are placed to stand slightly above the top edge of each cell or cavity for a purpose
hereafter described, the remaining surface of table or bench, not occupied by the
cells or cavities, is covered with cotton twill, cloth, sheet india-rubber or with any soft
suitable material (which will protect the skin or surface of the plates or sheets of glass
from injury) laid slightly below the level of the upper surface of the pieces of the
soft indiarubber surrounding the cells or cavities, that is level about with the upper
edge of the cells or cavities. The plates or sheets of glass are placed on the table or
bench, the air exhausted from the cells or cavities from below them by means of the
air exhausting pump and a vacuum is formed which retains the plates or sheets
of glass in position without the aid of the bed of Plaster of Paris usually employed,
the plates or sheets of glass are then ground, smoothed or polished in the usual
manner by the ordinary machinery employed.
If necessary a little Plaster of Paris or other suitable cement can be employed
to close the joints or spaces between and at outer edges of plates or sheets of glass to
assist in forming the vacuum especially when being fixed for the grinding process.
By the above method I save the using of Plaster of Paris in a very large degree
if not totally saving same; the time occupied in laying down and taking up the plates
or sheets of glass is shortened also certain risks of breakage avoided especially in the
process of polishing when the sheet is more fragile and the loss by breakage more
serious.
I have not illustrated my invention carried out by forming grooves or depressions
in the surface of tables as described in the first part of my Provisional Specification
as 1 prefer the cellular or cavity system but the grooves would simply form long
cells or cavities which however would have to be divided by plain surfaces where the
edges of two plates or sheets of glass come together and as the sizes vary this mode
of construction is not so convenient as cells or cavities.

page_text: 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
First. In the grinding, smoothing or polishing of plate or sheet glass securing
the plates or sheets upon the table or bench by the pressure of the atmosphere upon
portions of the surface by a vacuum being formed under such portions substantially
as described and illustrated.
Second. For the purpose of grinding, smoothing or polishing plate or sheet glass
by securing the plate or sheet upon the table or bench by the pressure of the
atmosphere, the construction and application of the table with cells or cavities
communicating by pipes or channels, controlled by cocks or valves, an air exhausting
pump substantially as described and illustrated.
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