Pulverizing Mill.
Year: 1899

page_text: Date of Application, 1st Aug., 1899-Accepted, 4th Nov., 1899
COMPLETE SPECIFICATION.
Pulverizing Mill.
I, ALBERT RAYMOND, Manufacturer, of No. 1402, Monadnock Building, Chicago,
Illinois, one of the United States of North America, do hereby declare the nature
of this invention and in what manner the same is to be performed to be particu-
Jarly described and ascertained in and by the following statement:—
This invention relates to improvements in pulverizing mills especially adapted
to the reduction of cement and similar substances to impalpable powder, the
particular class of pulverizing mills to which my invention more particularly
relates being that in which the pulverizing is accomplished by a combined crush-
ing and grinding action of rollers having a bodily revolution as well as an axial
rotation.
The prime object of my invention is to have the revolving crushing rollers
capable of free and unrestrained axial rotation and bodily movement parallel
with the axes of rotation and at the same time provide a mill that shall be cheap
and simple in construction, economical of operation and that shall have the
maximum capacity and efficiency.
:
Another object is to have the grinding faces of the rollers and bowl, in such
a machine, substantially parallel at all times regardless of the distance of the
roller from the crushing ring of the bowl and hence regardless of the size of the
material being operated upon.
A further object is to utilize to the maximum the gravity as well as the centri-
fugal force of revolving rollers in the crushing and grinding operation, whereby
is avoided the bounding and skipping of the rollers in action, while the efficiency
of the machine is greatly promoted.
Other objects are to insure the prompt discharge of the dust from between the
grinding rollers and the bowl, without allowing the same to settle into the bowl;
to protect the bearings of the rollers against the lodgment of dust thereon, which
would otherwise seriously interfere with the operation of the machine; and to
provide certain novel details for the carrying out of these objects.
The foregoing, and such other objects as may hereinafter appear, are attained
by the devices illustrated in the accompanying drawings, in which
Figure 1 represents a central vertical section through a pulverizing mill
embodying my invention.
Figure 2 represents a central vertical section through the bowl of the mill.
Figure 3 represents a horizontal section through the mill, taken on the
line 3 3 of Figure 1.
Figure 4 represents an enlarged vertical section on the line 4-4 of Figure 3.
Figure 5 represents a detail side elevation more particularly illustrating the
atmospheric port leading to the bearings.
Figure 6 represents a vertical section through the bowl on the line 6-6 of
Figure 3, looking in the direction indicated by the arrows but showing the
rollers removed.
Figure 7 represents a detail sectional view of the crusher head.

page_text: Figure 8 represents an oblique section thereof on the line 8-8 of Figure 7,
looking in the direction indicated by the arrows.
Figures 9 and 10 represent detail perspective views of the plows.
Similar letters of reference indicate the same parts in the several figures of the
drawings.
So far as relates to the broad idea of my invention, I may here state that it is
immaterial how the impalpable powder, or dust produced by my mill, is removed
therefrom, but for the purposes of illustration I have shown in Figure 1, in con-
nection with the mill, an air separator which is automatic in its operation when
once the machine is set in motion.
Referring by letter to the accompanying drawings, and more particularly to
Figure 1, the machine consists in general of a bowl a and rollers b, b, between
which the cement is pulverized, the dust passing up through the cylindrical
chamber c between the double cones d and e under the deflector f and out through
the discharge pipe g, the direction of the dust being equally illustrated by the
arrows. The dust is drawn out by an exhaust fan, the induction port of which is
connected with the pipe g and the eduction port of which is connected with a dust
collector of any suitable construction. From the collector the cleaned air is
returned to the spiral air-duct surrounding the bowl of the mill and thence into
the mill and out again in the manner previously described, but dust laden, thus
making a complete circuit. It is not deemed necessary to illustrate either the
fan or any dust collector, for, as far as concerns the broad idea of my invention
it is immaterial how the dust laden air is drawn out of the mill or out of the
pipe g, and it is equally immaterial what becomes of the dust laden air and
whether the same is returned, after separating the dust therefrom, to the mill
or whether fresh air is continuously supplied to the mill through the supply air-
duct has before described.
The combination of the air separator shown, with my new mill, is particularly
advantageous, however, because the heavy particles that are not carried out of
the separator by the air, and which represents the ". tailings" of the separator,
fall back directly into the mill for regrinding, without any other handling, some
of such heavy particles falling back after entering the space between the cones d
and e and others falling back after passing over and into the cone d where they
come in contact with the annular deflector f. This latter portion of the heavy
particles must, of course, have means for escape from the cone d and in my present
machine I have provided a cone valve i, adapted to enter and find a seat upon the
lower end of the cone d. This valve is adjustably supported upon a rod j and
may be set at any desired point by means of a set screw k to provide a suitable
opening between the valve and the cone.
Obviously, part of the dust laden air, as illustrated by the arrows, must neces-
sarily pass through this valve opening and of course opposes the fall of the smaller
and lighter pulverized particles of cement which pass over into the cone d, but
are temporarily checked by the deflector f. By a proper adjustment of the valves
in the opening, the quantity of air passing through this channel may be readily
adjusted so as to insure the continuous rise and discharge of the dust out through
the exhaust or discharge pipe g, while at the same time it will not be sufficiently
strong to force any of the smaller pulverized particles from the cone d upward
and into the discharge pipe.
The rod of the valve may be supported in any suitable manner upon any
stationary part of the machine, but, because of its convenience, I prefer to support
said rod upon the dome t of the atmospheric inlet provided for supplying air to
prevent the lodgment of dust on the roller bearings, as will be described in detail
further on,
such dome and inlet being clearly illustrated in dotted lines in
Figure 5.
The bowl a of the mill, which is stationary, is provided with a suitable annular
lining m along the bottom and part way up the side walls thereof and with a
wearing ring n reaching from about the center of depth to the upper edge of the

page_text: bowl, which ring constitutes the crushing and grinding face of the bowl against
which the rollers b, b, work. The inner periphery of the ring n, it will be
observed, is substantially in a vertical plane and the working face of the roller b
is bevelled as at o so as to extend obliquely to the axis of the roller and sub-
stantially parallel with the face of the ring n. It is manifest that the working
face of the ring n might be at an angle instead of vertical and the bevel or incline
of the working face of the roller may be correspondingly changed so as to lie
parallel therewith.
There may be any desired number of crushing rollers, four being shown in the
drawings, but all of them are arranged to rotate on an oblique axis, and as each
roller is capable of endwise movement or bodily movement parallel with its axis,
the opposing grinding faces of said rollers and the ring n will remain always
substantially parallel no matter how near together or far apart such faces may be,
and regardless of whether these grinding faces are in a vertical plane or at any
angle between the horizontal and vertical.
To accomplish this the rollers are preferably provided with comparatively long
hubs p, which are loosely sleeved upon fixed stud shafts q secured in the crusher
head r, so that when the latter is rotated the rollers will be caused to revolve
about the axis of rotation of the head which is coincident with that of the bowl
and crushing ring. The hubs of the rollers enter freely into recesses s in the
crusher head, which recesses are of sufficient depth to allow of considerable end-
wise movement of the hubs upon the stud shafts. The hubs are prevented from
leaving the stud shafts and coming entirely out of the recesses by the contact of the
rollers with the ring n. In Figure 4 the left-hand roller is shown in its extreme
outward position, while the right-hand roller is shown partly retracted from the
ring as it would be when forced back by the interposition of the material being
operated upon between it and the ring.
The crusher head is axially supported upon a vertical shaft t, to which the head
is keyed or otherwise rigidly secured, the lower end of said shaft being stepped
in a suitable bearing at the bottom of the machine, the bearing shown being the
conical projection on bottom of the cup resting upon the end of a threaded bolt u
projecting into the cavity of the step and engaging the central depression in the
end of the shaft. This shaft may be caused to revolve in any suitable manner,
such as by means of the bevelled gear keyed thereon, meshing with a corre-
sponding bevelled pinion w mounted upon a power shaft a driven by a pulley y
or any other suitable manner.
It will thus be observed that when the shaft t is rotated the crusher head r
rotates with it, and, through the intermediary of the stud shaft q entering loosely
in the hubs p of the rollers, causes the latter to revolve about and within the
bowl, the said rollers being forced to impact against the crushing face or ring
of the bowl under the combined influence of centrifugal force and the gravity
of the rollers. Consequently the maximum possible crushing force is exerted by
the rollers and this, of course, greatly enhances the certainty of continuous
and practically uninterrupted rotation of the rollers, which, though free to move
away from the crushing face of the bowl when large lumps or masses of the
material being operated upon are interposed between the rollers and the bowl, yet
such movement of the rollers is opposed by the combined gravity and centri-
fugal force thereof and hence there will be no slipping or uneven action thereof
In fact such action of the rollers will reduce the material being operated upon
to an impalpable powder in an unprecedented short space of time.
To insure the prompt removal of the dust or powder produced by the rollers,
I propose to introduce through lateral tangential ports 7 in the walls of the bowl,
at different points along the periphery thereof, jets of air which enter at the
bottom of the bowl below the crushing ring n and which, under the influence of
the suction applied to the discharge pipe g, forms a continuous upward spiral
current across the rollers and across the crushing faces thereof, carrying off the
dust as rapidly as it is formed. I prefer to admit the air to these lateral tangential

page_text: ports from the single spiral duct h to which the air may be supplied to any
suitable source, but obviously there may be separate pipes and separate sources of
supply for each port.
To prevent the lodgment of the dust upon the bearings of the rollers I provide
for the establishment of a current of air in the chambers s in which the hubs of
the rollers work, which chambers, as will be more clearly seen in Figure 4, have
open connection with the passage through which the air is conducted. To accomplish
this I provide vertical ducts 2 in the crusher head which are open to the atmos-
phere through the dome 1 and which lead down through an annular passage
formed by an apron 3 depending from the crusher head and surrounding the hub 4
of the bowl. The course of the air in its passage through the mill is plainly
illustrated by the arrows in Figure 4. There is no place of ingress for the dust,
into the chambers s and into the hubs of the rollers, except at the ends of the
bearings of the crusher head, where protection is afforded by a packing of
ordinary character. By setting up the current past the chambers and down
within the apron 3 the rising of the dust to reach this chamber is absolutely
prevented, because there will, at all times, be a strong current downward through
the apron, induced by the suction at the discharge end of the machine.
To prevent the accumulation of the larger and heavier particles of the material
being worked upon in the bottom of the bowl, which might, to some extent,
interfere with the action of the crushing rollers, and also to insure the more
rapid and thorough pulverizing of the material, I propose to have a constant
delivery of the material from the bottom of the bowl to the crotch formed between
each roller and the bowl, which operation shall be continuous, notwithstanding
the revolution of the rollers about the bowl. To this end I provide in front of
each roller a plow 5 which are preferably tubular with an inclined floor and
curved longitudinally to conform to the arc of the bowl. These plows, as more
clearly illustrated in Figure 6, are supported upon arms 6 radiating from the
apron 3 and as the apron is rigidly secured to, and depends from, the crusher
head, it, of course, rotates in unison therewith and thus carries the plows along
in advance of the rollers. There is one plow for each roller, so disposed that the
material is picked up thereby from the bottom of the bowl and forced up the
inclined floor of the plow and discharged from the upper end thereof into the
crotch between the crushing roller and the ring or jaw. It will thus be seen
that by the use of these plows in advance of one roller, or one or more of them,
as may be preferred, there can be no accumulation of the material in the bottom
of the bowl, and so long as there is any material in the bowl, the rollers will not
be idle, although operating above the bottom of the bowl, because the material
will be forcibly lifted up and discharged by the plows into the crushing jaws
formed by the roller and bowl. It is therefore obvious that the effectiveness
of the machine will be greatly promoted and the product thereof greatly increased
by the use of these plows, which, though not essential to the broad idea of my
invention, are at the same time desirable for the reasons above mentioned.
A pulverizing mill embodying my invention possesses numerous advantages
over such machine as heretofore constructed, chief among which may be mentioned
the simplicity and economy of construction, the readiness with which worn or
broken parts may be removed, the effectiveness thereof for pulverizing to almost
any degree of fineness, even to the production of an impalpable powder at a
comparatively slow speed, and the utilizing, to the fullest extent, of the grinding
and pulverizing force resulting from the operation of the machine combining
gravity with centrifugal force, whereby the successful operation of the machine
may be accomplished with the minimum expenditure of power for operating the
same. It is obvious that numerous changes may be made in the construction
and mode of operation of a pulverizing mill, embodying my invention, the con-
struction herein illustrated being simply one form of embodiment, but all
such changes are contemplated by, and would fall within, the purview of my
invention. For instance, while I have shown and described rollers as having a

page_text: free axial rotation and bodily movement on an axis oblique to the plane of its
orbit, that is upon stud shafts extending downwardly from the horizontal,
obviously the degree of inclination of the stud shafts is immaterial and will be
varied according to the work to be performed by the mill.
While my invention broadly contemplates a machine in which the crushing
rollers are capable of a free axial rotation, upon fixed axes, a free bodily move-
ment parallel with the axes thereof, but toward and away from the crushing face
of the bowl while traversing their orbits, it is to be observed as a peculiarity
of the present machine that the axes of the crushing rollers have a downward
and outward inclination with reference to the main vertical axis around which the
rollers travel in their orbital movement; that the downward and outward inclina-
tion of the axes of the rollers is constant or unchangeable, and that in conse-
quence of this fact the crushing faces of the rollers maintain, under all conditions,
their parallelism with the inner surface or crushing face of the ring or bowl
against which they act.
It is to be further observed that, owing to the downward and outward inclina-
tion of the axes of the rollers, the downward movement of the rollers, under the
influence of gravity, has the effect of carrying or urging the rollers outward toward
the inner surface or crushing face of the bowl. It is also to be noted that, owing
to the inclination of the axes, the centrifugal force developed by the rapid move-
ment of the rollers in traversing their orbits has a further tendency, or a tendency
in addition to that of gravitation, to carry the rollers outward toward the sur-
rounding ring or bowl.
In consequence of the facts above stated the rollers are free to rise and recede
from the inner surface or crushing face of the bowl in a manner which admits
of their adjusting themselves easily to the varying coarseness of the material
under treatment, while at the same time this material is subjected at all times
to the crushing and grinding action between surface which are parallel and
from rollers which are free to rotate upon their axes, which are free to move
toward and away from the material being operated upon while traversing their
orbits, and which, during the operating of the machine, are at all times subjected
to the combined influence of gravity and centrifugal force tending to drive them
against the crushing face of the bowl.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. In a pulverizing mill, the combination with a stationary bowl provided
with a crushing face on its inner periphery, of one or more rollers capable of a
free axial rotation upon fixed axes and a free bodily movement parallel with
the axes thereof, but toward and away from the crushing face of the bowl and
means for imparting an orbital travel to said roller or rollers, each of said rollers
having a single crushing face oblique to its axis of rotation and parallel with
the crushing face of the bowl, substantially as described.
2. In a pulverizing mill, the combination with a stationary bowl provided with
a crushing face on its inner periphery, of one or more rollers having axes of
fixed inclination and capable of a free axial rotation and a free bodily move-
ment parallel with the axes thereof, but toward and away from the crushing
face of the bowl and means for imparting an orbital travel to said roller or
rollers, each of said rollers having a single crushing face oblique to its axis of
rotation and parallel with the crushing face of the bowl, substantially as
described.
3. In a pulverizing mill, the combination with a stationary bowl, of one or
more rollers having fixed axes oblique to the vertical and capable of a free axial
rotation and a free bodily movement parallel with the axes thereof, but toward
and away from the crushing face of the bowl and means for imparting an orbital
travel to said roller or rollers about a vertical axis, substantially as described.

page_text: 4. In a pulverizing mill, a driving head rotating on a vertical axis, gravitating
conical crushing rollers carried by said head, their axes having a downward and
outward inclination with reference to the axis of the head and an encircling ring
or bowl against which said rollers act, substantially as described.
5. In a pulverizing mill, the combination with a stationary bowl having an
upright crushing face, an upright shaft extending axially through said bowl, a
crusher-head rigidly secured to said shaft, and one or more fixed stud-shafts
extending downwardly and outwardly from said head, of a roller loosely mounted
on each of said shafts and capable of a free bodily movement parallel with the
axes thereof, each of said rollers having oblique crushing faces parallel with
the crushing face of the bowl, substantially as described.
6. In a pulverizing mill, the stationary bowl having annular grinding surface,
the rotating crusher head and its oblique stud-shafts, the rollers journalled on
said shafts and capable of bodily movement lengthwise thereof, the apron fixed
to and depending from the crusher head and opening into the bottom of the bowl,
the exhaust above the bowl, air inlet from the exterior below the crushing surfaces,
ducts extending through the crusher head past the journals and opening within
the apron, and tubular ploughs carried by arms extending from the apron, sub-
stantially as described with reference to Figures 1, 3, 4, and 6 of the drawing.
Dated this 31st day of July 1899.
BOTTOMLEY & LIDDLE,
154, St. Vincent Street, Glasgow, Applicant's Patent Agents.