Improvements in Centrifugal Roller Mills.
Year: 1896

page_text: Date of Application, 13th Jan., 1896
Complete Specification Left, 7th Oct., 1896-Accepted, 21st Nov., 1896
PROVISIONAL SPECIFICATION.
Improvements in Centrifugal Roller Mills.
We, HERMANN PROPFE of 8 Bernwardstrasse and GERHARD ZARNIKO of
10 Bahnhofplatz both in Hildesheim, in the Empire of Germany, Manufacturers,
do hereby declare the nature of this invention to be as follows:-
This invention has for its object improvements in centrifugal roller mills and is
shown in the accompanying drawings, in which,
Figure 1 is a vertical section of the machine;
Figure 2, a horizontal section;
Figure 3, a view of a special arrangement of the rollers;
Figure 4, an elevation showing the method employed for stretching the flexible
sieve.
One or more naves or bosses m provided with arms n are mounted on a vertical
shaft b. These arms at their outer ends are each formed with a hole to receive a
pin or hinge bolt o. Levers p are mounted to pivot or oscillate on said hinge
bolts, and these levers each carry at one end revoluble rollers r, and at the other.
end are subjected to the pull of a spring g which is carried by and pulls towards
the nave.
The grinding action of the rollers is such that on the whole system
being rotated in a suitable direction, the rollers are pressed against the mill casing
by centrifugal force assisted by the action of the springs and disintegrate the
material to be ground which lies between the grinding surfaces.
The rollers may be adjusted by means of the springs q to a given pressure
against the mill casing and yet be free, without other manipulation, to run over
large lumps of the material to be ground which may lie between the grinding.
surfaces.
If the rollers be caused to rotate in such a way that, as seen in Figure 2, they
run in a direction contrary to that of the hands of a clock, a very considerable
advantage may be obtained by a small alteration. It is in fact only necessary to
make the angle, enclosed by the arm n and the lever p, greater than a right angle
(see Figure 3) to establish a knee lever action which very considerably increases
the disintegrating effect when the roller encounters an obstruction. If a be the
above named angle and P be the power or force which comes into action at the
hinge point o in the direction of the tangent to the track or circuit, the power
conveyed to the roller is
P
(a
cos
-
90). If a = 90° therefore (as shown in
Figure 2) P., if a = 127° for instance
etcetera.
=
1.25 P, if a = 135° about = 1.43 P,
As shown in Figure 1, two grinding systems are employed one above the other
with a fan h mounted to rotate between them so as to drive the air and with it the
finely ground material out through a sieve lining or frame g. The letter indicates +
the way in which the finely ground product leaves the machine.
Material which
is not rendered fine enough by the first grinding falls into the lower grinding
apparatus and is there again ground. In order to allow of the sieve lining being
easily changed, the following arrangement is adopted. A flexible frame is formed
over which when extended the silk or gauze is strained, and the whole is then.
placed round the curve of the machine casing.

page_text: The frame consists of two flexible bars a, Figure 4, of wood, steel or the like
material, connected with one another by means of crossbars b. Several of such
sieve frames may be employed instead of one.
Dated this 11th day of January 1896.
WM. P. THOMPSON & Co.,
Of 6 Lord Street, Liverpool, Agents for the Applicants.
We, HERMANN PROPFE of 8 Bernwardstrasse and GERHARD ZARNIKO of
10 Bahnhofplatz both in Hildesheim, in the Empire of Germany, Manufacturers,
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:-
This invention has for its object improvements in centrifugal roller mills and is
shown in the drawings accompanying the Provisional Specification, in which,
Figure 1 is a vertical section of the machine;
Figure 2, a horizontal section;
Figure 3, a view of a special arrangement of the rollers;
Figure 4, an elevation showing the method employed for stretching the flexible
sieve.
One or more naves or bosses in provided with arms n are mounted on a vertical
shaft b. These arms at their outer ends are each formed with a hole to receive a
pin or hinge bolt o. Levers p are mounted to pivot or oscillate on said hinge bolts,
and these levers each carry at one end revoluble rollers r and at the other end are
subjected to the pull of a spring q which is carried by and pulls towards the nave.
The grinding action of the rollers is such that on the whole system being rotated
in a suitable direction, the rollers are pressed against the mill casing by centrifugal.
force assisted by the action of the springs and disintegrate the material to be
ground which lies between the grinding surfaces.
The rollers r may be adjusted by means of the springs q to a given pressure
against the mill casing and yet be free, without other manipulation, to run over
large lumps of the material to be ground which may lie between the grinding
surfaces.
If the rollers be caused to rotate in such a way that, as seen in Figure 3, they
run in a direction contrary to that of the hands of a clock, a very considerable
advantage may be obtained by a small alteration. It is in fact only necessary to
make the angle, enclosed by the arm n and the lever p, greater than a right angle
(see Figure 3) to establish a knee lever action which very considerably increases
the disintegrating effect when the roller encounters an obstruction. If d be the
above named angle and P be the power or force which comes into action at the
hinge point o in the direction of the tangent to the track or circuit, the power
conveyed to the roller is
P
.
If d = 90° therefore (as shown in Figure 2)
cos (d-90)
this power P. if d = 127° for instance it = 1.25 P, if d = 135° about = 1.43 P.
etcetera.
As shown in Figure 1, two grinding systems are employed one above the other
with a fan h mounted to rotate between them so as to drive the air and with it the
finely ground material out through a sieve lining or frame g. The letter lindicates
the way in which the finely ground product leaves the machine. Material which
is not rendered fine enough by the first grinding falls into the lower grinding
apparatus and is there again ground. .In order to allow of the sieve lining being

page_text: easily changed, the following arrangement is adopted. A flexible frame is formed
over which when extended the silk or gauze is strained, and the whole is then
placed round the curve of the machine casing.
The frame consists of two flexible bars a, Figure 4, of wood, steel or the like
material, connected with one another by means of crossbars b. Several of such
sieve frames may be employed instead of one.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. A centrifugal roller mill with springs pressing the rollers on the mill casing,
characterised by the rollers being mounted on the ends of two armed levers, the
other ends of which are connected to springs whereby the rollers are pressed
against the mill casing substantially as hereinbefore set forth.
2. In an apparatus of the kind described, the arrangement of the levers (p)
carrying the rollers at an obtuse angle to a radius drawn from the axis of
rotation (6) of the system to the point of rotation (o) of the respective lever (p)
and the rotation of the apparatus towards the opening of the obtuse angle, whereby
the material to be ground is not drawn but pushed and a knee lever action is
established during the grinding substantially as described.
3. lu an apparatus of the kind described, a flexible sieve lining consisting of
flexible frames, over which the silk or gauze is stretched, the whole being adapted
to be placed round the casing, whereby a rapid changing of the sieve linings may
be effected substantially as described.
Dated this 6th day of October 1896.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicants.