IMPROVEMENTS IN MACHINES FOR THE MANUFACTURE OF WOOD PULP
Year: 1881

page_text: LETTERS PATENT to Frank Wirth, of the Firm of Wirth and Company, Patent
Solicitors, at Frankfort-on-the-Main, in the Empire of Germany, for an
Invention of "IMPROVEMENTS IN MACHINES FOR THE MANUFACTURE OF
WOOD PULP." A communication from the Society for the Manufacture of
Wood-pulp at Grellingen, in the Republic of Switzerland.
PROVISIONAL SPECIFICATION left by the said Frank Wirth at the Office
of the Commissioners of Patents on the 11th June 1881.
IN
FRANK WIRTH, of the Firm of Wirth and Company, Patent Solicitors, at
Frankfort on the Main, in the Empire of Germany. "IMPROVEMENTS
MACHINES FOR THE MANUFACTURE OF WOOD PULP." [A communication from
the Society for the Manufacture of Wood-pulp at Grellingen, in the Republic of
Switzerland.]
This Invention relates to improvements in machines for reducing wood to pulp
by means of grind-stones, the wood being pressed in an oblique direction against a
vertical grind-stone.
At present two kinds of machines for reducing wood to pulp are in use, one
works with a vertical stone (system Voelter), the other with a horizontal stone
(system Sylrecht). In both these classes of machines the wood is reduced on the
outer rim or periphery of the stones. Mongolfier constructed a machine with a
horizontal grinding stone by which the wood was reduced on the upper side of the
stone, this however never produced practical results.
The two first methods have the disadvantage that the rim or periphery of the
stone (mostly quartz) has necessarily to be cut to make the stone round, and thus
the stone does not bite equally at all parts of its periphery.
By grinding on the upper side of a horizontal stone this is avoided, but the wood
pulp does not run off with sufficient readiness, some portions thereof passing twice
and three times under pressure, and thereby the fibre of these portions becomes too
short. Another disadvantage is that the pivot and spindle of the stone are very
rapidly worn out, as they have to bear not only the weight of the stone itself but
also the pressure of the wood on the upper surface of the stone.

page_text: The improvements which constitute the present Invention obviate all these
difficulties, and a machine embodying the same moreover presents the following
advantages :-
1. By grinding upon the flat side of the stone the point of the grain of the stone
is always at an angle to the wood, and consequently a better pulp with a more even
fibre is produced.
2. By using the flat side of the stone the wood can be reduced in a direction
parallel to its grain just as quickly as across the same, thus producing a longer
fibre which is of great importance in wood-pulp manufacture. On the rim or
periphery of a stone the wood can be reduced lengthwise of the fibre, only at great
loss both as to quality and quantity, as the wood becomes concave and the year-
rings on the one half of the block will jam and adhere to the stone.
3. If the rim of the stone is not used in the manner heretofore practised it is
left free and may be provided with iron bands, the dangerous breaking of the stone
being thus prevented, besides which the speed is increased, and thus an increased
and improved production are obtained.
4. In using this machine the wood can be pressed against the stone not only on
one but on both sides thereof, and a much greater production is thus obtained,
besides which the pressure being equal on both sides of the vertical stone the axle
of the same has only to carry the weight of the stone and no pressure, thus the
journals will wear out less rapidly and less power will be required.
In carrying the said Invention into practice, I construct a machine as follows,
that is to say :-
I provide a horizontal shaft upon which is placed the grind stone protected by a
suitable covering. On both sides of said shaft are situated guides or guiding
devices, in which the wood to bo reduced is placed in such a manner that the stone
bites and removes the fibre lengthwise. The wood is pressed against the stone by
means of a head plate and a ratchet bar or rack gearing with a pinion. Constant
pressure of said pinion is obtained by its shaft carrying a wheel, a strap, to the end
of which a sufficient weight is attached, being wound around said wheel. The
weight thus exerts traction upon the wheel, and thereby pressure is brought to bear
upon the pinion above mentioned.
The pressure may however be produced by springs, hydraulic power, or other
suitable means. If the wood is pressed at an angle from below the axle of the
stone, the necessary pressure can be derived from the weight of the stone itself, if
on the other hand the wood is placed at an angle above the axis of the stone, the
weight of the wood itself can be used for pressing it against the stone.
A hand wheel is also provided and serves to withdraw the pressure from the
wood when necessary.
For washing the wood pulp off I provide suitable pipes. On the frame of the
machine is provided a sharpening apparatus.
The pulp is delivered by a suitable spout. The wood is pressed against the
stone preferably by four receivers, any suitable number may however be used, and
they may be arranged on one or on both sides of the stone as desired; moreover,
the periphery or either or both sides of the stone can be used.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Frank Wirth in the Great Seal Patent Office on the 10th December
1881.
FRANK WIRTH, of the Firm of Wirth and Company, Patent Solicitors, at
Frankfort-on-the-Main, in tho Empire of Germany. "IMPROVEMENTS IN
MACHINES FOR THE MANUFACTURE OF WOOD-PULP." A communication from
the Society for the Manufacture of Wood-pulp at Grellingen, in the Republic of
Switzerland.
The present improvements relate to machines for reducing wood to pulp by
means of grind-stones, the wood being pressed in an oblique direction against one
or both sides of a vertical grind-stone.
At present two classes of machines for reducing wood to pulp are in use, one
works with a vertical stone (system Voelter), and the other with a horizontal stone
(system Sylrecht). In both of these classes of machines the wood is reduced on
the outer rim or periphery of the stones. Mongolfier constructed a machine with a
horizontal grind-stone by which the wood was reduced on the upper side of the
stone, this however never produced practical results.
The two first methods have the disadvantage that the rim or periphe.y of the
stone (mostly quartz) has necessarily to be cut in order to make the stone round,
and thus the stono does not bite equally at all parts of its periphery.
By grinding on the upper side of a horizontal stone this is avoided, but the wood
pulp does not run off with sufficient readiness, portions thereof passing twice and
three times under pressure, and thereby the fibre of these portions becomes too
short. Another disadvantage is that the pivot and spindle of the stono are very
rapidly worn out, as they have to bear not only the weight of the stone itself but
also the pressure of the wood on the upper surface of the stone.
The improvements which constitute the present Invention obviate all these
disadvantages and present the following advantages :—
1. By grinding upon the flat side of the stone the point of the grain of the stone
is always at an angle to the wood, a better pulp with a more equal fibro is thus
produced.
2. By using the flat sido of the stone the wood can be reduced in a direction
parallel to its grain just as quickly as across the same, thus producing a longer
fibre which is of great importance in wood pulp manufacture. On the rim or
periphery of a stone the wood can be reduced lengthways of the fibre, only at great
loss both as to quality and quantity, as the wood becomes concave and year rings
on the one half of the block will jam and adhere to the stone.
3. If the rim of the stone is not used in the manner heretoforo practised it is
left free and may be provided with iron bands, the dangerous breaking of the stone
being thus provented, besides which the speed can be increased, and thus an
increased and improved production attained.
4. According to my improvements the wood can be pressed against the stone not
only on one but on both sides thereof, and a much greater production is thus
obtained, besides which the pressure being equal on both sides of the vertical stone
the axle of the latter has only to carry the weight of the stone and no pressure,
thus the journals will less speedily become worn and less power will be required.
The improved apparatus is represented in the accompanying Drawings, in
which,-
Figure 1 represents an elevation, and

page_text: On both sides of the shaft A are situated the guides a, a, in which the wood to
be reduced is placed in such a manner that the stone bites and removes the fibre
lengthwise. The wood is pressed against the stone by means of a head plate c
and ratchet bar or rack 6 gearing with the pinion c.
The constant pressure on
the pinion e is obtained from its shaft f and the wheel g attached to the latter, a
strap having a sufficient weight at its free end, being wound upon the said wheel,
so that the weight pulls the latter in one direction and exerts prossure upon the
pinion e.
The pressure can also be produced by springs, hydraulic pressure, or by other
suitable means. If the wood is pressed at an angle from below the axle of the
stone, the necessary pressure can be derived from the weight of the stone itself, if
on the other hand the wood is placed at an angle above the axis of the stone, the
weight of the wood itself can be used for pressing it against the stone. Tho hand
wheel i serves to withdraw the pressure from the wood when necessary. The wood
pulp is washed off the stone by means of the pipes h, h. On the frame is situated
suitable sharpening apparatus. The pulp passes out at m.
In the Drawing a machine with four wood receivers is represented. It will
however be understood that any suitable number thereof may be used, also that
the same can be arranged on one or on both sides of the stone as desired. The
periphery as well as one or both sides of the stone may be used without departing
from the principle of this Invention.
Having thus fully described the said Invention and the manner of performing
the same, I wish it understood that I claim,―
A wood pulp machine having the vertical stone in combination with the
receivers a, the rack, the pinion e, and the weight wheel g, and with or without
side sharpening apparatus, all substantially as and for the purposes set forth.
In witness whereof, I, the said Frank Wirth, have hereunto set my hand
and seal, this Third day of December, in the year of our Lord One thousand
eight hundred and eighty one.