IMPROVEMENTS IN APPARATUS FOR STRAINING PULP USED IN THE MANUFACTURE OF PAPER."
Year: 1881

page_text: LETTERS PATENT to George Tidcombe, junior, of the Firm of Messrs. G.
Tidcombe & Son, of Watford, in the County of Herts, Papers Makers'
Engineers, for an Invention of "IMPROVEMENTS IN APPARATUS FOR STRAINING
PULP USED IN THE MANUFACTURE OF PAPER."
PROVISIONAL SPECIFICATION left by the said George Tidcombe, j*., at
the Office of the Commissioners of Patents on the 11th March 1881.
"
GEORGE TIDCOMBE, junior, of the Firm of Messrs. G. Tidcombe & Son, of
Watford, in the County of Herts, Papers Makers' Engineers. IMPROVEMENTS IN
APPARATUS FOR STRAINING PULP USED IN THE MANUFACTURE OF PAPER."
"Plates "or" screens" hitherto used in straining pulp are made of metal with
grooves cut therein to serve as countersinks for saw curves or slits through which
the pulp is passed in the straining process. These grooves or countersinks limit
the distances of the slits from each other according to their angles and the thickness
of the plates, and their sides and ends offer surfaces for sediment and dirt to
accumulate thereon, which choke the slits and so impede the passage of the pulp in
the straining thereof.
The present Invention obviates these defects by applying one countersink or cell
to a series of slits instead of a countersink to each slit. The number of slits is
thereby increased in the same area of plate, and one apparatus or strainer can be
used instead of two or more, or finer slits can be used to pass the same quantity as
through coarser plates hitherto in use. The bottom of the plates or the grooves
are free from sharp corners and surfaces for accumulations of dirt or sediment to
adhere to, and the plates themselves can be cleansed with greater facility than
heretofore.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said George Tidcombe, jr., in the Great Seal Patent Office on the
10th September 1881.
•
GEORGE TIDCOMBE, junior, of the Firm of Messrs. G. Tidcombe and Son, of
Watford, in the County of Herts, Paper Makers' Engineers. "IMPROVEMENTS IN
APPARATUS FOR STRAINING PULP USED IN THE MANUFACTURE OF PAPER."
This Invention relates to certain improvements in apparatus for straining pulp
for making pulp for making paper, and relates to the plates for straining the pulp,
and is a further improvement upon pulp strainer apparatus such as is referred to in
the Specification of Letters Patent No. 5018, dated 2nd December 1880.
Plates or screens hitherto used in straining pulp are made of metal with grooves
cut therein to serve as countersinks for saw curves or slits through which the pulp
is passed in the straining process.
'
These grooves or countersinks limit the distances of the slits from each other
according to their angles and the thickness of the plates, and their sides and ends
offer surfaces for sediment and dirt to accumulate therein, which choke the slits
and so impede the pulp in the straining thereof.
The present Inventian obviates these defects by applying one countersink or cell
to a series of slits instead of a countersink to each slit. The number of slits is
thereby increased in the same area of plate, and one apparatus or strainer can be
used instead of two or more, or fewer slits can be used to pass the same quantity
as can be passed through coarser plates hitherto in use. The bottom of the plates
or the grooves are free from sharp corners and surfaces for accumulation of dirt or
sediment to adhere to, and the plates themselves can be cleansed with greater
facility than heretofore.
In the Drawings Fig. 1 is a plan view of underside of section of strainer plate
made according to this Invention.
Fig. 2, a plan of the upper side or face of strainer surface; Fig. 3, a section at
line a, b, of Fig. 1; Fig. 4, a transverse section at line c, d, of Fig. 1; and Fig. 5
view on enlarged scale of portion of the plate constructed from rolled sheet and
provided with strengthening bars, and showing clearing tool introduced into the
slit.
A are the countersinks, grooves, or cells upon the underside of the strainer plate
for receiving a series of slits B forming the strainer passages; and in making such
plates I cast them with the countersinks A therein, which I prefer, or I saw, plane,
cut-out, or drill the sunken portions or grooves in a suitable cast or rolled solid
plate of brass or copper; or I subject such solid plate when hot to a pressing or
stamping operation by hydraulic or other suitable pressing or stamping machinery
to form the countersinks, grooves, or cells of the strainer plates, and plane off or
clear away these pressed portions from the face side of the plates, leaving enough
metal, about of an inch in thickness, as the crown of the cells or countersinks to
allow for the strainer passage ways or slits to be made therein; and instead of
dissolving away the edges of the slits by acids, as is sometimes done, I use a
graving tool made of fine emery, or a piece of emery stone, or a fine file of proper
shape for taking off the "wire" edges only, that is, to remove the burr arising from
the cut of the saw.
In repairing strainer plates when from wear the strainer slits become irregular or
too coarse, I take such plates and cut all the slits to a uniform size, and then by
electro-deposition of metal close the slits again to the requisite degree of fineness
for the straining purpose, or I subject the old plates to the aforesaid stamping or
pressing operation to close the slits and then recut the slits of the plates in regular

page_text: manner. The slitted portion of the plate being of equal thickness in this improved
construction, it is evident that the slits can be "reclosed" uniformaly by pressure.
To enable me to have such an increased number of slits as I gain in this
improved strainer plate I sustain the bars C by another bar D so as to obtain
equal strength of bars with a lighter plate, and also this allows of the using of the
wedge shaped cutter or cleaner, shown in Fig. 5, as it is strong enough without
buckling for such slits.
As shown in Fig. 5, the plates are sometimes made of a thin sheet of the thickness
required for the crown of the countersinks, grooves, or cells, and this plate with the
closely alitted strainer portion will be mounted upon strengthening bars C¹, D¹, to
which the plate will be rivetted.
Having now described the nature and particulars of my said Invention I
claim,―
Firstly. In the construction of a strainer plate the employment of one counter-
sink, groove, or cell, the crown whereof has made therein the series of slits serving
for the straining purpose, as and for the purpose herein set forth.
Secondly. The strainer plates herein described with the series of fine close slits
made as and for the purpose herein set forth and shown by the respective Figures
of the accompanying Sheet of Drawings.
In witness whereof, I, the said George Tidcombe, junior, have hereunto set
my hand and seal, this Eighth day of September, in the year of our Lord
One thousand eight hundred and eighty one.
In the presence of
WALTER A. BARLOW,
Patent Agent & Engineer,
6, St. Paul's Chyard.,
London, E.C.
G. TIDCOMBE, JN³. (L.S.)