Improvements in the Manufacture of Strainer or Knotter Plates for Straining Paper Pulp, Wood Pulp, and the like.
Year: 1890

page_text: Date of Application, 23rd Oct., 1890
Complete Specification Left, 21st July, 1891-Accepted, 22nd Aug., 1891
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Strainer or Knotter Plates for
Straining Paper Pulp, Wood Pulp, and the like.
We, HENRY BURNETT WATSON and JOHN STANLEY WATSON, both of High
Bridge Works, Newcastle on Tyne, in the County of Northumberland, Members
of the firm of Henry Watson & Sons, Engineers Brass and Iron Founders, do
hereby declare the nature of this invention to be as follows:-
Strainer plates or knotter plates for use in straining paper pulp wood pulp and
the like have been constructed in various forms. According to one construction
separate plates or sections each formed with a row of slits have been constructed to
slide or enter between the ribs or bars of a suitable frame to which the said plates
could be fastened by screws or otherwise. For the purpose of affording the requisite
strength to resist the pressure against the one side resulting from the formation of
a partial vacuum at the other which is necessary to effect the straining operation
the plates have been made with ribs between the slits. According to another plan
there have been formed in a single casting strainer plates with ribs the ribs
corresponding to the frames of the before described strainer plates and the interven-
ing parts corresponding to the removable plates above referred to and having slits
formed therethrough.
The first mentioned construction has been open to objection in consequence of the
liability of fibres and of resin (in the case of wood pulp) to adhere to the ribs and
thus to cause accumulations such as eventually to produce in paper manufactured
from the pulp what are known as knots or blotches resulting in waste owing to the
parts of the paper containing such defects being unsuitable for use.
The secondly mentioned construction of strainer or knotter plates has also been
open to objection owing to the liability of portions of the pulp to adhere thereto. Not
only so but when in consequence of wear or the action of acids, such as sulphurous
or sulphuric acid present for example in what is known as sulphite wood pulp, any
of the slits have become too large to act efficiently in straining the pulp, the whole
plate has become useless.
Now the present invention has reference to an improved manufacture of strainer
or knotter plates in which renewable slitted parts of peculiar construction are
combined with a frame in such a manner as to produce a compound strainer or
knotter plate that shall be comparatively light and strong, shali offer considerable
resistance to the action of acids and shall not present obstructing or accumulating
surfaces such as those herein before referred to as causing the formation of knots or
blotches in the product. And in order that the nature of this invention may be
clearly understood, reference will now be had in describing the same to the annexed
sheet of illustrative drawings in which
Fig. 1 is a plan or top view of a removable section or part of a compound strainer
plate according to this invention.
Fig. 2 is an under side view of the same.
Fig. 3 is an end view thereof.
Fig. 4 is a plan or top view of a complete compound strainer or knotter plate
comprising a number of plates such as that illustrated in Figs. 1 to 3 inclusive
combined with a frame adapted to receive and hold the same.
a is a frame that may be constructed of any suitable material such as cast bronze;
it is made with longitudinal bars (three are shewn) with two end transverse
bars c c and with six or any other convenient number of transverse bars d connecting
the longitudinal bars. In the example the central longitudinal bar and the trans-
verse bars are formed with raised parts 'c'd' the depth of which is equal to the

page_text: thickness of the removable sections e which are made with bevelled edges adapted
to fit into bevelled grooves in the said parts b¹ c¹ d' as represented in Figs. 4 and 5,
so that each of the removable sections can be slidden into position in the frame and
be there secured by screws as at ff, and any one or more of them can, in case of
need, be readily removed and replaced, or another be substituted therefore if
necessary. For the purpose of dispensing with numerous ribs or projections liable
to cause obstruction such as hereinbefore referred to, whilst providing strainer plates
having the requisite strength, and which shall not be liable to injury by acid, the
removable sections are constructed of a suitable alloy such as copper and tin in the
proportions of say about 95 per cent. of copper to 5 per cent. of tin, and with longitudinal
rows of slits g g with an intervening part having the same depth or thickness as
the remainder of the plate, those parts of the outer portion of the plate and longi-
tudinal part of the plate which correspond to the ends of the slits having
bevelled or curved formation so that the slits gradually increase in length towards
the under surface of the plate so as to obviate liability to adherence or accumulation
of portions of pulp. The above described construction will enable removable
sections of the requiste strength to be made of considerably larger area than has
been found practicable with removable sections as heretofore usually constructed,
thus greatly reducing the obstructing area incidental to grooves or bars such as obtain
in strainer plates of constructions now in use.
Dated this 23rd day of October 1890.
a
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicants.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Strainer or Knotter Plates for
Straining Paper Pulp, Wood Pulp, and the like.
We, HENRY BURNETT WATSON and JOHN STANLEY WATSON, both of High
Bridge Works, Newcastle-on-Tyne, in the County of Northumberland, Members of
the Firm of Henry Watson & Sons, Engineers, Brass and Iron Founders, 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:-
Strainer plates or knotter plates for use in straining paper pulp, wood pulp, and
the like, have been constructed in various forms. According to one construction
separate plates or sections each formed with a row of slits have been constructed to
slide or enter between the ribs or bars of a suitable frame to which the said plates
could be fastened by screws or otherwise. For the purpose of affording the
requisite strength to resist the pressure against the one side resulting from the
formation of a partial vacuum at the other, which is necessary to effect the straining
operation, the plates have been made with ribs between the slits. According to
another plan there have been formed in a single casting, strainer plates with
ribs, the ribs corresponding to the frames of the before described strainer plates
and the intervening parts corresponding to the removable plates above referred to
and having slits formed therethrough.
The first mentioned construction has been open to objection in consequence of the
liability of fibres and of resin (in the case of wood pulp) to adhere to the ribs and
thus to cause accumulations such as eventually to produce in paper manufactured from
the pulp what are known as knots or blotches resulting in waste owing to the parts
of the paper containing such defects being unsuitable for use.
The secondly mentioned construction of strainer or knotter plates has also been
open to objection owing to the liability of portions of the pulp to adhere thereto.
Not only so but when, in consequence of wear or the action of acids (such as
sulphurous or sulphuric acid, present, for example, in what is known as sulphite wood

page_text: pulp) any of the slits have become too large to act efficiently in straining the pulp,
the whole plate has become useless.
Now the present invention has reference to an improved manufacture of strainer
or knotter plates in which renewable slitted parts of peculiar construction are
combined with a frame in such a manner as to produce a compound strainer or
knotter plate that shall be comparatively light and strong, shall offer considerable
resistance to the action of acids, and shall not present obstructing or accumulating
surfaces such as those hereinbefore referred to as causing the formation of knots
or blotches in the product. And in order that this invention may be clearly under-
stood, reference will now be had, in describing the same, to the sheet of illustrative
drawings left with our Provisional Specification and to the accompanying two
sheets of additional drawings.
Fig. 1 is a plan or top view of a removable section or part of a compound
strainer plate according to this invention.
Fig. 2 is an under side view of the same.
Fig. 3 is an end view thereof.
Fig. 4 is a plan or top view of a complete compound strainer or knotter plate,
comprising a number of plates such as that illustrated in Figs. 1 to 3 inclusive
combined with a frame adapted to receive and hold the same.
Fig. 5 is a section in the line xx of Fig. 4.
a is a frame that may be constructed of any suitable material, such as cast
bronze; it is made with longitudinal bars (three are shewn) with two end
transverse bars c c, and with six or any other convenient number of transverse bars d
connecting the longitudinal bars. In the example, the central longitudinal bar
and the transverse bars are formed with raised parts b c d the depth of which
is equal to the thickness of the removable sections e which are made with bevelled
edges adapted to fit into bevelled grooves in the said parts b, c, d, as represented
in Figs. 4 and 5, so that each of the removable sections can be slidden into
position in the frame, and be there secured by screws, as at ff, and any one or
more of them can, in case of need, be readily removed and replaced, or another
be substituted therefor if necessary. For the purpose of dispensing with numerous
ribs or projectious liable to cause obstruction such as hereinbefore referred to, whilst
at the same time providing strainer plates having the requisite strength, and which
shall not be liable to injury by acid, the removable sections are constructed of a
suitable alloy such as copper and tin, in the proportions of say about 95 per cent.
of copper to 5 per cent. of tin, and with longitudinal rows of slits
with an
intervening part which in the example shown in Figs. 1 to 5 inclusive, is of the
same depth or thickness as the remainder of the plate, those parts of the outer
portion of the plate and longitudinal part of the plate which correspond to
the ends of the slits having a bevelled or curved formation so that the slits
gradually increase in length towards the under surface of the plate, so as to
obviate liability to adherence to accumulations of portions of pulp. The above
described construction will enable the removable sections of the requisite strength
to be made of considerably larger area than has been found practicable with
removable sections as heretofore usually constructed, thus greatly reducing the
obstructing area incidental to grooves, bars or ribs such as obtained in strainer
plates of constructions now in use.
99
Fig. 6 of the accompanying drawings is a plan or top view illustrating a
removable section similar to those herein before described excepting that the
intervening part is made to extend slightly above the general level or surface
of the section.
Figs. 7, 8, 9, 10, 11, and 12 are cross sections to a larger scale illustrating
various forms in which the intervening part can be made so as to extend
either above or below, or both above and below the general surface or surfaces of
the sections, in order to form a rib or ribs arranged at right angles to the
slits and which will impart additional stiffness and rigidity to the sections. Such
removable sections with extended rib-or ribs may be cast, rolled or pressed,

page_text: Figs. 13 and 14 are similar views to Figs. 4 and 5 respectively, illustrating a
complete strainer or knotter plate with removable sections having such extended
intervening parts h.
Instead of making the strainer plates of the same thickness at the margin as
they are made where the slits g occur, as shown in the previously described
constructions of sections, we have found it desirable for the purpose of securing
the requisite strength to make the marginal portions thicker as represented
in Figs. 15. 16, 17, 18, and 19, which are similar views to Figs. 1, 2, 3, 4, and 5
respectively, e¹ e¹ being the thickened margins of the sections e.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. The hereinabove described improved construction of strainer or knotter plate
wherein the removable sections e e, supported in the frame composed of longitudinal
and transverse bars bb, c c, d d with raised parts b'', c' c¹, d' d', consists each of a
metallic plate through which are formed rows of slits gg, the said rows of slits
being separated by an intervening part having either the same depth or thickness
as the remainder of the plate, or made to extend above or below, or both above and
below the general level or surface of one or both sides of the plate so as to form a
rib or ribs of the kind mentioned, and the ends of the slits are bevelled or curved
for the purpose specified, whether the marginal portions be thickened or not.
2. A strainer or knotter plate such as referred to in the preceding claim, having
removable sections e e such as described made by casting pressing or rolling thin
plates of an alloy of copper and tin in (or approximately in) the proportions of
95 per cent. of copper and 5 per cent. of tin and forming therein rows of slits 9 9 with
intervening strengthening part / substantially as described with reference to the
examples illustrated.
Dated this 18th day of July 1801
HENRY BURNETT WATSON.
JOHN STANLEY WATSON.
W. Lloyd Wise,
46, Lincoln's Inn Fields, London, Agent for the Applicants.