IMPROVEMENTS IN THE MANUFACTURE AND TREATMENT OF STRAINERS FOR PROVISIONAL SPECIFIC
Year: 1882

page_text: LETTERS PATENT to George Tidcombe Junior of Watford Iron Works,
Watford in the County of Herts, Paper Makers' Engineer for an invention of
"IMPROVEMENTS IN THE MANUFACTURE AND TREATMENT OF STRAINERS FOR
PROVISIONAL SPECIFICATION left by the said George Tidcombo at the
Office of the Commissioners of Patents on the 21st April 1882.
GEORGE TIDCOMBE Junior of Watford Iron Works Watford in the County of
Herts Paper Makers' Engineer "IMPROVEMENTS IN THE MANUFacture
TREATMENT OF STRAINERS FOR STRAINING PULP
"
AND
This Invention relates to certain improvements in or upon the subject mattor of
Letters Patent bearing date 2nd December 1880 No 5018 and bearing date
11th March 1881 No 1060 granted to me.
Strainer plates or screens employed in the straining of pulp in the manufacture
of paper and fibrous manufactures are made of metal which is worked out or
reduced to the required form and depth by cutters or drills producing grooves or
cells in the crowns of which slits are made for the passage of the fibres. These
slits are made by revolving saws driven at a high speed which invariably leave a
brirr or sharp edge at the ends and edges of the slits the sides of the slits also
thereby obtain irregularities such as may be seen in a magnified degree in ordinary
boards sawn by a circular saw.
These imperfections impede the passage of the fibres of the pulp especially at the
ends of the slits and great loss of time ensues before they are worn away by the
flow of the pulp itself and before they are thus brought into proper condition for
work and there are caused at the same time points or centres of accumulation
which make strings and lumps that choke plates and fall away at intervals spoiling
large quantities of paper.
I remedy these defects by taking off or rounding the edges and ends of the slits
to a suitable form increasing their durability at the same time and give at once to
new plates the natural curve they obtain by lengthened wear without impairing the
accuracy of the slits.

page_text: After slitting the plates I pass through and against them any fluid or semi-fluid
carrying in suspension any matter of a grinding or abrasive character under
pressure such as a sand or emery laden blast or by steam or air or water or other
fluid which from a head or under pressure will act abrasively or as finely reducing
means.
In the treatment of old or warm plates for renewing the slits according to this
Invention I first subject the plates to the to the operation of the sand blast or
abrasion fluid to prepare the metal for receiving by electro-deposition the non-
corrosive coating of metal, the plates are then re-slit and finally treated by the sand
blast or abrasion fluid as above described.
These improvements extend to the strainer itself and for the purpose I give a
jog or vibratory effect to the plate as well as to the elastic suction underneath also
in the driving motions for working the strainers the reciprocating action hitherto
in use has been irregular in effect and in order to counteract this I use a duplex or
balancing motion which make it regular. I use improved means for increasing the
flow of pulp over the surface of the strainer plates by extra pump power and a full
washing way so as to free them of choking stuff.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent and of
an Order of the Lord Chancellor filed by the said George Tidcombe in the
Great Seal Patent Office on the 14th November 1882.
GEORGE TIDCOMBE Junior of Watford Iron Works, Watford in the County of
Herts Paper Makers' Engineer "IMPROVEMENTS IN THE MANUFACTURE
TREATMENT OF STRAINERS FOR STRAINING PULP
"
AND
This Invention relates to certain improvements in or upon the subject matter of
Letters Patent bearing date 2nd December 1880 No 5018, and bearing date
11th March 1881, No 1066, granted to me.
Strainer plates or screens employed in the straining of pulp in the manufacture
of Paper and fibrous manufactures are made of metal, which is worked out
channelled or reduced to the required form and depth by cutters or drills producing
grooves or cells in the crowns of which slits are made for the passage of tho
fibres. These slits are made by revolving saws driven at a high speed which
invariably leave a burr or sharp edge at the ends and edges of the slits, the sides
of the slits also thereby obtain irregularities such as may be seen in a magnified
degree in ordinary boards sawn by a circular saw, These imperfections impede
the passage of the fibres of the pulp especially at the ends of the slits, and great
loss of time ensues before they are worn away by the flow of the pulp itself and
before they are thus brought into proper condition for work, and there are caused
at the same time points or centres of accumulation which makes strings and lumps
that choke plates and fall away at intervals spoiling large quantities of paper.
I remedy these defects by taking off these irregularities and rounding the edges
and ends of the slits to a suitable form and give at once to new plates the natural
curve they obtain by lengthened wear without impairing the accuracy of the
slits.
After slitting the plates I pass through and against them any fluid or semifluid
carrying in suspension any matter of a grinding or abrasive character under pressure
such as a sand or emery laden blast with steam or air as the Vehicle (this blast
must not be of too heavy a character) or water or other fluid is employed as the
Vehicle which under pressure or by any washing process will act abrasively or as
finely reducing means upon the rough surfaces of the metal.
This abrasive reduction of the surfaces of the worked metal of the plates I some-
times effect by the working of the plates up and down or backwards and forward
or in a circular direction in a birth of water wherein is held in suspension fine
emery powder and the pressure of the fluid and abrasive action of the emery is
sufficient and effects the object well. Direction is here given to the use of emery
as it is the best and most convenient abrasive.
In the treatment of old or worn plates made according the said former Patent
No 1066, A.D. 1881, for renewing the slits I employ the rolled crown plate as
described and shown in the drawing Fig. 5 of the specification thereof and I tin-
solder the crown plate to the strengthening bars or frame and then after cutting
the slits subject the plate to the abrasive operation.
These improvements also extend to the strainer itself and for the purpose I give
a jog or vibratory effect to the plate as well as to the elastic suction underneath
also in the drawing motions for working the strainers the reciprocating action
hitherto in use has been irregular in effect and in order to counteract this I use
a duplex or balancing motion which makes it regular. Also I uso improved means
for increasing the flow of pulp over the surface of the strainer plates by extra

page_text: -
pump power and a full washing way so as to free them of choking stuff In the
drawings:-
Fig. 1 is an enlarged view of the ordinary strainer plate showing at a the burr
or sharp edge thereof.
Fig. 2 is a similar view after they have been treated according to my invention
with rounded or abrased edges a¹
Fig. 3 is an enlarged view of my improved strainer plate according to my said
former Patent No 1066 and treated according to this invention.
This does well for straining pulp of short fibre but with the use of the elastic
diaphragm of the strainer as set forth in the Specification of the said Letters
Patent No 5018 A.D. 1880 with pulp of long fibre tho fibres become lapped around
the metal between the slits.
Fig. 4 shows in like view as Fig. 3 the plate made deeper with arched grooves
or cells b thereunder down the points or projections c whereof the pulp will be
washed and combed out by the flow and the lapping of the long fibre will be
avoided.
Fig. 5 shows a side view of one of the slits illustrating the saw curves alluded
_to_and_the_sharp ends at a when the circular saw is made to run past their length
on the upper surface and Fig. 6-shows-the-same when treated by my process with
the rounded edges a¹.
Fig. 7 shows the square but sharp end given to the slits when finished off square
by the usual upright or hand saw used for the purpose.
Fig. 8 shows the same after treatment by my process. In rounding the edges a
these may-be-preliminarily treated by a flat bladed edge file and then abrased or
finished off as described.
This mode of treating strainer plates is applicable for slitted strainer plates other
- than those employed in the manufacture of paper
For the purpose of giving a lighter-action to the reciprocating joints or driving
parts of the strainers already described in my former Patent No 5018-A-D-1880-
and shown in the Figures 5 and 6 of Sheet 2 of the drawings annexed to the
Specification thereof I construct such parts of light malleable iron, brass or steel,
or of wood, or wood in combination with such metals and work them with balanced
cams A, Figs. 9, 10 and 11 of Sheet 2 and guide the india rubber diaphragms as
shown in the said Figures. The cams are made with one or more flats thereon
and are run under a metal plato B affixed to the india rubber bottom so as to
equalize the pulsations and elasticity of the india rubber diaphragin or bottom.
The drawing Fig. 9 shows the strainer without the india rubber diaphragm
applied and may be so used by working the metal plate B as a piston fitting
properly in the frame of the strainer and in this case a strainer of circular form
will be inost convenient.
Fig. 12 shows the details of fixing the strainer plates for the purpose of giving
to the strainer plates themselves a vibratory action for which purpose I hold them
between india rubber flanges C of suitable thickness.
Figs. 13 and 14 are elevation and plan respectively of construction for the
purpose of obtaining any required flow or wash over or against the strainer plates
so that they may pass the stuff more readily, instead of running the overflowing
stuff directly into an auxiliary strainer which sometimes chokes, I run it into a
box or reservoir where the backwater joins and draw it from this into the suction
of a pump or other compressing means so as to exert a washing and disintegrating
pressure upon the fibres and to force or raise the stuff to an auxiliary placed higher
than usual. For such treatment of pulp at this stage I may place coare strainer
plates in the suction pipe of the pump or force the pulp by extra pump power
through a nozzle or thin vein or I may employ disintegrating rollers as described
in my Patent No 5018 A.D. 1880 separately or in conjunction with such pump
power. The pulp is thereby fractionally reduced and strained and readily passes
an auxiliary having fine plates.
Such means with ordinary modifications are applicable to all kinds of strainers

page_text: working with auxiliaries, my primary object being in conjunction with my
improved plates to deliver an equally strained pulp to the paper making machino
continuously
The whole of the back water is hereby used up instead of so much being wasted
as is usually the case and finer strainer plates can be used.
In the said Figs. 13 and 14 D shows the auxiliary strainer placed above the
other strainer E. It is usually placed below.
The pulp is delivered from the stuff chest at F and flows over the strainer E into
the trough G thence to the box reservoir H when the backwater from the paper
making machine meets it; it is then lifted by the backwater pump into the
auxiliary D.
For the purpose of employing the extra pump power or wash over the strainer
plates, in making papers by hand, in vat mills, I employ the arrangement illustrated
in Figs. 15 and 16.
The stuff being properly prepared is delivered into the stuff chest A and circu-
lated through the missing box E by means of the stuff pump B and backwater
pump C and then over the sand catcher D.
No 1 strainer recoives the stuff in the usual manner but the coarser portions are
washed over it and thence lifted by the backwater pump C into No 2 strainer, the
fine stuff passing through No 1 into the vats E; that portion which passes through
No 2 strainer is led again into the mixing box F when the new stuff mixes with
it by the nction of the stuff pump and the coarser portions are occasionally scraped
off No 2 strainer which is done without altering the make of paper.
And for such vat mills an auxiliary strainer may be placed below the primary
strainer as is usual in machine mills but I prefer it above in all cases as before
described..
Having now described the nature and particulars of the said invention I
claim:-
The improvements in the manufacture and treatment of strainers and strainer
plates for straining pulp as herein set forth and described in reference to the
respective figures of the accompanying drawings.
In Witness whereof I the said George Tidcombe Junior have hereunto set
my hand and seal, this cloventh day of November in the year of our
Lord one thousand eight hundred and eighty-two.