IMPROVEMENTS IN MACHINERY FOR REDUCING FIBBES TO PULP
Year: 1856

page_text: LETTERS PATENT to Laban Clarke Stuart, of New York, in the United
States of America, for the Invention of "IMPROVEMENTS IN MACHINERY FOR
REDUCING FIBBES TO PULP."-A communication from Joseph Kingsland,
junior.
Sealed the 10th February 1857, and dated the 29th November 1856.
PROVISIONAL SPECIFICATION left by the said Laban Clarke Stuart at the
Office of the Commissioners of Patents, with his Petition, on the 29th
November 1856.
I, LABAN CLARKE STUART, of New York, in the United States of America,
do hereby declare the nature of the Invention for "IMPROVEMENTS IN MACHINERY
FOR REDUCING FIBRES TO PULP," to be as follows:-
This Invention has for its object improvements in machinery for reducing
fibres to pulp. For these purposes a cylinder is used closed at each end, and
by preference this cylinder is of large diameter as compared with its length;
though this is not essential. On the interior of the cylinder is a revolving disc
of nearly as large diameter as the interior of the cylinder within which it
revolves, and the disc is of such thickness as to leave a small space between
each of its two side surfaces and the two end covers or ends of the cylinder.
The surfaces of the disc and of the interior of the cylinder are formed with
grooves, cutters, or knives, or with teeth to aid in the grinding process. Tho
disc receives a quick rotating motion, it being fixed to the end of a suitablo

page_text: shaft or axis (driven by a steam engine or other power), which passes through
a stuffing box formed in one of the covers or ends of the cylinder, and there is
provision made for the disc and its axis to move a small distance to and fro
within the cylinder.
The stuff is fed with water from an elevated reservoir or cistern into the
cylinder at one end towards the centre, and by reason of the source of supply
being elevated, there will be a proportional hydraulic pressure. The pulp
flows off from the other end of the cylinder by a pipe, which can hang per-
pendicularly, or its lower end may be more or less elevated, by which the
speed of flow through it may be regulated, and the stuff kept for a longer or
shorter time under the grinding process, or the flow of the stuff through the
machine may be regulated by other means.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Laban Clarke Stuart in the Great Seal Patent Office on
the 29th May 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, LABAN
CLARKE STUART, of New York, in the United States of America, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-ninth day of November, in the year of our
Lord One thousand eight hundred and fifty-six, in the twentieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Laban Clarke Stuart, Her special licence that I, the said Laban Clarke
Stuart, my executors, administrators, and assigns, or such others as I, the said
Laban Clarke Stuart, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
MACHINERY FOR REDUCING. FIBRES TO PULP," a communication from Joseph
Kingsland, junior, upon the condition (amongst others) that I, the said Laban
Clarke Stuart, my executors or administrators, by an instrument in writing under
my, or their, or one of their hands and seals, should particularly describe and
ascertain the nature of the said Invention, and in what manner the same was to
be performed, and cause the same to be filed in the Great Seal Patent Office
within six calendar months next and immediately after the date of the said
Letters Patent.

page_text: NOW KNOW YE, that I, the said Laban Clarke Stuart, do hereby declare
the nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof, that is to say :-
This Invention has for its object improvements in machinery for reducing
fibres to pulp. For these purposes a cylinder is used closed at each end, and
by preference this cylinder is of large diameter as compared with its length,
though this is not essential. On the interior of the cylinder is a revolving disc
of nearly as large diameter as the interior of the cylinder within which it
revolves, and the disc is of such thickness as to leave a small space between
each of its two side surfaces and the two end covers or ends of the cylinder.
The surfaces of the disc and of the interior of the cylinder are formed with
grooves, cutters, or knives, or with teeth, to aid in the grinding process. The
disc receives a quick rotatory motion, it being fixed to the end of a suitable
shaft or axis (driven by a steam engine or other power), which passes through
a stuffing box formed in one of the covers or ends of the cylinder, and there is
provision made for the disc and its axis to move a small distance to and fro
within the cylinder.
The stuff is fed with water from an elevated reservoir or cistern into
the cylinder at one end towards the centre, and by reason of the source
of supply being elevated, there will be a proportional hydraulic pressure.
The pulp flows off from the other end of the cylinder by a pipe, which can
hang perpendicularly, or its lower end may be more or less elevated, by which
the speed of flow through it may be regulated, and the stuff kept for a longer
or shorter time under the grinding process, or the flow of the stuff through the
machine may be regulated by other means.
Having thus stated the nature of the Invention, I will now proceed more
fully to describe the same.
Figure 1 represents a vertical section of a "stuff engine" upon the improved
plan; Figure 2 represents an elevation of one end, and Figure 8 an elevation
of the other end of the same. The stock from which paper of fine quality is
made usually consists of rags varying in strength and fineness of fibre. These
rags, in the process of manufacturing them into paper, are reduced by grinding
them in water to a mass of pulp. Two descriptions of machines have been
heretofore generally employed for this purpose, similar in construction, and
termed respectively the "washing engine" and the "stuff engine."
washing engine is employed to cleanse and rough-grind the rags, which, after
being subjected to this operation are called "half-stuff."
The
Tho "stuff engine" is employed to complete the grinding of the "half-stuff"

page_text: into fine pulp. This "stuff engine" consists of an annular trough or vat, in
which a current of water with the "half-stuff" to be ground floating therein may
be kept flowing round. This vat has a fixed grinding bed placed across its
bottom, and a revolving grinding cylinder placed above this bed, leaving a
narrow space between the two. The face, both of the bed and of the cylinder,
is armed with blunt steel knives, those on the face of the cylinder working past
those on the face of the grinding bed, in the manner of shear blades, but so as
to bruise and tear rather than cut the half-stuff, as sharp knives working as
shears would tend too much to granulate the fibre by cutting it into short
lengths instead of crushing it into pulp.
. This bed and revolving cylinder constitute the grinder of this engine, and
they also form a partition across the trough or vat. The rotary motion of the
cylinder dashes the water and rags from one side of the partition to the other
through the spaces between the knives, thus depressing the level of the water
in the trough on that side of the partition whence the water flows, and raising
it on the opposite side; the water thus disturbed seeks to regain its level by
flowing, from that side of the partition at which it is highest, round the annular
trough or vat to the opposite side of the partition; this establishes a current
round the vat, which continues while the cylinder is in motion, and keeps the
whole mass of rags passing repeatedly through between the knives, where they
are repeatedly ground until the fibre is reduced. It necessarily follows from
the manner in which this stuff engine operates, that the fine and the coarse,
the tender and the strong fibres are all subjected to an equal amount of
grinding, and therefore the coarse and strong fibre must be ground too little,
or the fine and tender fibre too much; in either case producing a pulp of
hetercogenous quality, which will impart a corresponding defect to the paper
made from it. But as the quality of the paper is most injured by insufficient
grinding of the fibre, the grinding is generally continued until the coarsest fibro
is well reduced, which grinds much of the more tender fibre to powder, a portion
of which flows off with the waste water and is lost; another portion of it is lost
at a subsequent stage of the manufacture, by draining off with the water from
the screen that transfers the pulp from the vat to the (Fourdrinier) machine,
for converting the pulp into sheets of paper. The loss from these two sources
has been estimated as high as fifteen per cent. of the whole quantity of rags
ground.
Another objection to this engine is, that its speed is limited to a certain low
rate, from the fact that, when the periphery of the cylinder of the grinder
begins to run above twelve hundred feet a minute, it repels the rags and water
in such manner as to retard their entrance between the grinding knives, and

page_text: when the speed of the cylinder is greatly accelerated, the current will be almost
arrested, and the grinding stopped. This limit to the speed of the stuff engine
it will be seen is a very serious objection, when its great bulk, and the large
amount of floor space it occupies, are taken into account, especially in manu-
factories doing an extensive business and requiring a large number of these
engines.
It is one of the objects of the Invention to remedy the before-mentioned
defects of the stuff engine, and this I accomplish by providing, in the improved
engine, for the withdrawal of the fibre from the action of the grinder the
moment it is sufficiently reduced, and leaving to be longer acted upon that
which requires more grinding, by which means the whole of the fibre, whether
strong or weak is reduced to pulp of uniform fineness, each part of it being
subjected to a degree of grinding proportioned to its strength. Further, by
rendering the feed independent of the motion of the grinder, the engine can
be run at any speed that its strength will sustain, and the work is done much
more rapidly than in the old engine, as the grinder can be run very fast, and
the half stuff thoroughly reduced by passing through it once; and by dispensing
with the annular vat, and feeding the stuff to the engine through a pipe, and
discharging the pulp therefrom by similar means, this engine is rendered very
compact, and requires less space tha that occupied by the engino heretofore in
use. In the process of grinding paper stock by means of the ordinary engines,
it is found that different kinds of fibre require the grinding surfaces of the
engine to be set at different distances, and almost all stock is so hetercogenous
in quality that the distances between the grinding surfaces require almost
constant variation to ensure the proper reduction of the fibre, and to prevent
the choking of the engine. To adjust the grinder by hand with such frequency
and nicety, although bighly desirable, is obviously impracticable. I have,
however, invented a grinder which adjusts itself as required; and this part of
the Invention consists in placing a revolving grinder between two stationary
grinders, the revolving grinder having free play on its axis to enable it to
move back and forth between the stationary grinders, to approach towards
either, as required; the fibre to be ground being caused to pass in a current
through the spaces between one stationary grinder and one side of the
revolving grinder, thence round the periphery of the revolving grinder, and
through the space between the opposite side of the revolving grinder and tho
other stationary grinder to the orifice of discharge. I have not only rendered
the revolving grinder self-adjusting, but I also purpose to take advantage of
its rotary motion to facilitate the feeding of the fibre to be reduced into it,
and the retention of the fibre within its action until sufficiently reduced. This

page_text: I accomplish by causing the fibre to be fed into the grinder at an orifice near
its axis on one side, and discharged by a similar orifice on the opposite side
after passing between the grinders from the centre to the circumference on
one side, and thence back again towards the centre on the opposite side, the
centrifugal action tending to carry the fibre from the centre to the circum-
ference on the feeding side, and to retard its passage from the circumference to
the centre on the discharging side of the grinder, thus operating to keep the
fibre longest near the circumference where the motion is greatest, and tho
grinding action consequently more energetic.
Lastly, in either grinding rags or other fibre to "half stuff," or in reducing
half stuff to pulp, it is frequently important to vary the rate at which the
fibrous matter is fed through the grinder, while the motion of the grinder
remains constant, but heretofore no means of accomplishing this object have
been in use.
It is one of the objects of the Invention to provide the means by which the
feed is rendered adjustable, and this part of the Invention consists in varying
the level of the nozzle of the discharge pipe relative to the level of the head
of water in the feed pipe, whereby the effective head of feed pressure is
varied, and as a matter of course the velocity of the feed current is cor-
respondingly varied. By reference to the accompanying Drawings the con-
struction and operation of the improved stuff engine will more fully appear.
It consists of a bed plate B, which supports two standards A, A, and a
hollow cylinder C, whose diameter is equal to about four times its length.
In a line with the central axis of this cylinder a shaft D is mounted in bearings
in the beads of the standards A, A. This shaft D passes through a stuffing
box S on the inner head or cover d' of the cylinder C, and projects about two-
thirds of the way across the space within the cylinder towards its outer head
or cover d. On this projecting end of the shaft D a disk E is secured, at
right angles to the shaft and concentric with it and with the cylinder; and
the play or movement of the disc to and fro within the cylinder may be
controlled by set screws b, b, or other suitable means. This disc E is somewhat
less in diameter than the cylinder, and in thickness the disc is about half the
length of the interior of the cylinder, so as to leave between it and the heads
or covers d', d, and between the periphery of the disc and the interior of the
cylinder a free space for a current of water, and rags, half stuff, or paper
pulp to flow through. There are, however, two projections or teeth formed
or fixed on the periphery of the disc, which projections or teeth are on opposite
sides of the axis, and they extend to such a distance from the periphery as
all but to come in contact with the interior periphery of the cylinder. The

page_text: inner surface of the heads or covers of the cylinder and the sides of the disc
are grooved in the usual manner of metallic grinders, or they may be armed
with teeth or knives of any suitable kind. An orifice is made in each head
of the cylinder C as near the centre as possible. The orifice in the outer
head d is connected by a pipe F with a tank above containing half stuff
mingled with water, kept well stirred and ready to be ground to pulp, the
level of the water in the cistern being kept uniform during the process. To,
the orifice in the inner head or cover d' a pipe G is attached by means of a
joint, rendered fluid tight by a stuffing box o, that permits the pipe to be
turned to set it with its mouth upward, downward, or in any intermediate
position, to vary the height between its mouth (which is the level at which
the pulp is discharged from the grinder) and the level of the water in the
feeding tank, by which the hydraulic pressure which feeds the fibre through.
the grinder is regulated. This is a simple and effective means of regulating.
the rate of the feed with both nicety and facility. Instead of making the
discharge pipe G rigid and arranging it to turn on a joint it may be made
flexible, and its mouth suspended by a cord on a hook or in a rack at various
heights. Numerous other modes it is quite obvious can be adopted of varying
the difference between the feed and the discharge level to regulate the feed,
but it is not necessary to particularize these modifications, as they will be
readily understood by the mechanic. The operation of the engine is as
follows: Rotary motion is communicated to the shaft D through the pulley
near its middle. In the arrangement shown the disc is about two and a
half feet in diameter, the interior of the cylinder is about one and a half
inches larger in diameter, and the disc is revolved about two hundred
revolutions per minute, these quantities may, however, bo varied. The disc
and also the heads or covers of the cylinder are cut or formed with curved
teeth, as shown in Figure 2. The fibrous materials to be ground are mixed
with about as much water as there is in finished pulp when used as a
Fourdrinier's paper making machine. The set screw b, at the outer end of
the axis D, is, when for the finest pulp, set so that the surface of the disc
only just clears the inner surface of the cover or head d', whilst the other
set screw 6 allows the disc to move away from the cover d³ towards the cover.
d. The mixed half stuff and water may now be let into the feed pipe F
from the tank above, and the hydraulic pressure, (usually about four feet,)
will force it into the cylinder through the space E, between the disc E and
the outer head d, round the periphery of the disc, and through the space f
to the discharge pipe G, where it will leave the cylinder, and entering, the
discharge pipe will pass through the same into any suitable receptacle. If

page_text: the feed current runs too fast (which will be ascertained by observing whether
the fibre is sufficiently ground) the mouth of the pipe G must be raised, and
vice versa.
The centrifugal motion of the disc E will cooperate with the
hydraulic pressure to pass the half stuff from the feed orifice near the centre,
where the motion of the disc is slow and but little grinding takes place,
towards the periphery, where the motion is greater and the grinding more
energetic; but when the current of water and fibre pass the periphery of the
disc and enter the space f on the opposite side the passage to the discharge
orifice is retarded by the centrifugal action of the disc. This retarding force
acts with the greatest effect upon the largest fibres, their specific gravity
being greater than that of any equal measure of any other portion of the
flowing mass. Moreover, the current carries the fibres through the grinder
at a speed inversely proportioned to their size, the more reduced fibres having
an area of surface for the current to act upon relatively far greater than that
of the longer fibres. In this way the reduced fibres are withdrawn from the
action of the grinder, while the coarser fibres are left for further reduction.
This separation of the finer from the coarser fibres during the process of
grinding is facilitated by the increased mobility which they acquire by reduction.
The fineness of the grinding it will be seen depends upon the bydraulic
pressure on the feed and the speed with which the disc of the grinder runs,
while the rate of feeding depends upon the hydraulic pressure. In case a
knot or lump of fibre should be fed into the grinder, the disc would yield,
moving towards the side opposite the knot, to allow the knot to pass freely
towards the periphery, where it would quickly be reduced by the energetic
action of that part of the grinder. While this reduction of the lump or knot
is going on at the feed side of the grinder, both the feeding and the discharge
are diminished by the crowding over by the knot of the revolving disc against
the discharge orifice. By this yielding of the disc all danger of clogging is
avoided, and at the same time the flow of unground fibre through the grinder
is prevented. Further, if the fibre is tender and easily reduced it will flow
freely through the grinder, and occupy but little more space on the feeding
than on the discharge side of the disc; but if the fibre is tough and grinds
slowly it will accumulate on the feed side and crowd the disc to the discharge
side, retarding the discharge, the strong fibre being in this way subjected to,
as it requires, more grinding action than the weaker fibre. This machine is
one devised for carrying the new and improved process into effect; but it
will be obvious to those skilled in the art of manufacturing paper that the
machinery may be modified and varied, and yet operate upon a like principle
of combination and construction.

page_text: Having thus described the nature of the Invention, and the manner of
performing the same, I would have it understood that I make no claim
to any of the mechanical parts separately, nor do I confine myself to the
details herein described; but what I claim is the combined machinery herein
described.
In witness whereof, I, the said Laban Clarke Stuart, have hereunto set
my hand and seal, this Twenty-eighth day of May, in the year of our
Lord One thousand eight hundred and fifty-seven.
Witness,
S. CARPMAEL.
L. C. STUART. (L.B.)