IMPROVEMENTS WASHING BREAKING AND BEATING ENGINES CR MACHINERY FOR THE MANUFACTURE OF PAPER PULP אן
Year: 1882

page_text: LETTERS PATENT to Christopher Aitchison of Loanhead in the County of
Midlothian, North Britain Engineer for an Invention of "IMPROVEMENTS
WASHING BREAKING AND BEATING ENGINES CR MACHINERY FOR THE
MANUFACTURE OF PAPER PULP
אן
"
PROVISIONAL SPECIFICATION left by the said Christopher Aitchison at the
Office of the Commissioners of Patents on the 11th November 1882.
CHRISTOPHER AITCHISON, of Loanhead, in the County of Midlothian, North
Britain, Engineer,
"IMPROVEMENTS IN WASHING, BREAKING, AND BEATING
ENGINES, OR MACHINERY FOR THE MANUFACTURE OF PAper pulp."
This Invention which relates to machinery for the manufacture of paper pulp
known as washing, breaking, and beating engines, has special reference to an
improved construction and arrangement of the cutting rolls and fixed knives or bed
plates of such machines, the object of which is to secure more even or regular action
of the knives on the pulp.
In ordinary beating engines for the manufacture or preparation of paper, the roll
is made in the form of a cylinder, and is consequently of equal diameter over all
parts of the surface. The bed-plate fixed under the roll is laid on a level, is of
equal width, and has an equal number of knives or cutting bars throughout.
Owing to the form of the roll, the pulp travels at the same speed under all parts
of its surface; and over the bed-plate it traverses the same extent of cutting surface,
whether circulating near the mid-feather, or central partition of the trough or vat
containing the pulp, or at its circumference.
But the contents of the trough nearest the mid-feather, having a much shorter
distance to travel than the contents nearest the circumference, pass more frequently
between the roll and the bed-plate, and are thus unduly broken up or ground, before
the outer orbit of pulp has been sufficiently acted upon.
My Invention consists (1) in making the roll of a conical shape instead of
cylindrical and fitting it in the vat so that the diameter of the roll greatest next

page_text: the outer rim of the trough or vat, and (2) in gradually increasing the number of
knives or bars in the bed-plate, from the end nearest the mid-feather to the end
nearest the outer rim of trough, and corresponding to the gradual increase in
diameter of the roll, thus giving a gradually increasing cutting surface from the
inner, or midfeather end of the bed-plate to the outer end. The bed-plate is laid
at an angle corresponding to the taper of the roll, and the breast and backfall of
the trough are made to suit the form and position of the bed-plate and roll.
By these improvements in the roll, bed-plate and trough, the pulp travelling
round the outer wall of the trough passes over a larger cutting surface on the bed-
plate than does the pulp circulating near the mid-feather. Compensation is thus
provided for the less frequent passage, under the roll and over the bed-plate of the
pulp travelling near the outer side of the trough. Owing to the tapering form of
the roll, a thorough mixture and interchange of the pulp is effected.
It is also drawn sooner under the knives at the wider end of the bed-plate, and
is delivered with greater velocity over the backfall and round the circumference of
the trough, where it should travel fastest, and the entire contents of the trough are
made to circulate more rapidly. The pulp is thus more regularly and efficiently
acted upon, and in a much shorter time than in an engine of the ordinary
description, and a better product is the result.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Christopher Aitchison in the Great Seal Patent Office on the
8th May 1883.
CHRISTOPHER AITCHISON, of Loanhead, in the County of Midlothian, North-
Britain, Engineer, "IMPROVEMENTS IN WASHING, BREAKING, AND BEATING ENGINES
OR MACHINERY FOR THE MANUFACTURE OF PAPER PULP."
My said Invention, which relates to machinery for the manufacture of paper pulp,
known as washing, breaking and beating engines, has special reference to an
improved construction and arrangement of the cutting rolls and fixed knives or bed
plates of such machines, the object of which is to secure more even or regular action
of the knives on the pulp.
In ordinary beating engines for the manufacture or preparation of paper, the roll
is made in the form of a cylinder, and is consequently of equal diameter over all
parts of the surface.
The bed plate fixed under the roll is laid on a level, is of equal width, and has an
equal number of knives or cutting bars throughout.
Owing to the form of the roll, the pulp travels at the same speed under all parts
of its surface, and over the bed-plate it traverses the same extent of cutting surface,
whether circulating near the mid-feather or central partition of the trough or vat
containing the pulp, or at its circumference. But the contents of the trough
nearest the mid-feather a much shorter distance to travel than the contents
nearest the circumference, pass more frequently between the roll and the bed-plate,
and are thus unduly broken up or ground, before the outer orbit of pulp has been
sufficiently acted upon.
My Invention consists (1) in making the roll of a conical shape, instead of
cylindrical, and fitting it within the vat, so that the diameter of the roll is
greatest next the outer rim of the trough or vat, and (2) in gradually increasing
the number of knives or bars in the bed-plate, from the end nearest the mid-feather
to the end nearest the outer rim of trough, and corresponding to the gradual
increase in diameter of the roll, thus giving a gradually increasing cutting surface
from the inner or mid-feather end of the bed-plate to the outer end. The bed-plate
is laid at an angle corresponding to the taper of the roll, and the breast and
backfall of the trough are made to suit the form and position of the bed-plate and
roll.
My said Invention is illustrated by the accompanying Drawings, in which
Figures 1 and 2 are respectively a plan and an elevation of a modification of the
improved pulp beating engine. Figure 3 is a transverse vertical section showing
the construction of the conical cutting roll and bed-plate. Figures 4 and 5 are plans
of two modifications of knife plates adapted for use with the conical roll; and
Figure 6 is a plan of the box in which the knife plates are fitted. The improved
beating engine comprises the usual trough or vat A formed with a central partition
or mid-feather A' round which the pulp material which is placed in the vat
circulates. The cutting roll B is fitted in the ordinary way in one of the divisions
of the trough A, and is carried by a spindle B' supported in bearing bushes B
fitted in the sides of the trough, the spindle being driven by a pulley B' and belt.
The cutting roll B is made of slightly tapering or conical form, the outer and being
of greater diameter than the end next the mid-feather A', and the knives b are
fixed longitudinally in the usual way. The knife plate C is formed of the ordinary
cutting knives or blades c, which are made to increase in number from the inuer to
the outer end. A number of the knives c are fitted parallel to each other, and

page_text: short lengths of additional knives are fitted in the outer end of the knife plate, to
give a greater breadth of cutting surface under the outer end of the tapered cutting
roll. The knife plate C is fitted in a box C' which is fitted to slide as usual through
an opening in the side of the vate A. The box C' rests on an inclined seat, so that
the cutting edges of the knives c are in planes parallel to those of the knives b of
the rolls, as is indicated in figure 3. The ordinary devices D for adjusting the
roll B vertically are provided.
By these improvements in the roll B, bed-plate C and trough A, the pulp
travelling round the outer wall of the trough A passes over a larger cutting surface on
the bed-plate C than does the pulp circulating near the mid-feather. Compensation
is thus provided for the less frequent passage under the roll B, and over the bed-
plate C of the pulp travelling near the outer side of the trough A. Owing to the
tapering form of the roll B, a thorough mixture and interchange of the pulp is
effected. It is also drawn sooner under the knives c at the wider end of the bed-
plate C, and is delivered with greater velocity over the backfall E and round the
circumference of the trough A where it should travel fastest and the entire
contents of the trough are made to circulate more rapidly. The pulp is thus more
regularly and efficiently acted upon, and in a much shorter time than in an engine
of the ordinary description, and a better product is the result.
Having now described the nature of my said Invention, and the manner in
which the same is to be performed, I declare that what I claim as my Invention
19
First. The combination, in a pulp beating engine, or machine, of-the-tapered or
conical cutting roll and tapered bottom knife-plate formed with an increasing
cutting surface towards the outer end, substantially as herein described and:
Cillustrated.
-
Second. In a pulp beating engine or machine, the conical or tapered-cutting_
roll B constructed and arranged, substantially as herein described and illustrated.
Third. In a pulp beating engine or machine, the construction and arrangement_
of the tapered bottom knife plato C with an increasing cutting-surface towards the
outer end, substantially as herein described and illustrated..