Grinding and Pulverizing Mills.
Year: 1893

page_text: Date of Application, 8th Mar., 1893
Complete Specification Left, 8th Dec., 1893-Accepted, 8th Mar., 1894
PROVISIONAL SPECIFICATION.
Grinding and Pulverizing Mills.
I, JOSEPH HUNT, citizen of the United States, residing in Allentown, County
of Lehigh, State of Pennsylvania, United States of America, Engineer, do hereby
declare the nature of this invention to be as follows:-
My invention relates to that class of grinding or pulverizing mills in which the
material to be ground is in a dry state and in which the grinding or pulverising
action is effected by rolls running against the inner face of a fixed ring, the objects
of my invention being to so construct a grinding or pulverizing mill of this class
as to insure the effective contact of the grinding rolls with the inner face of the
ring whether the mill is run fast or slow, to effectually prevent the escape of the
finely ground or pulverized material from the mill casing, or its access to the roll
bearings, to provide for the ready feeding of the mill, preferably by a central
opening, to provide suitable and efficient means of lubrication, and to so hang the
grinding rolls as to permit of the ready application or removal of the same when
desired and lessen the friction due to the rotation of the same on their axes.
above objects are carried out by the construction of the apparatus of which the
following is a description.
The
Mounted on a suitable base or foundation is a casing inside which is an inner
dished circular pan or trough, for containing the material to be pulverized, surmounted
by a horizontal metallic grinding ring connected to the said outer casing in such
manner that an annular space or cavity is left between the said casing and dished
pan or trough and the grinding ring. In a vertical and central prolongation of the
said dished trough is a bearing in which rotates a vertical driving shaft whose
lower end works in a suitable bearing or footstep in the foundation while its upper
part is secured to a dished plate or roller carrier to which are adjustably pivotted
swinging hangers each terminating inwardly in a cylindrical bearing or sleeve in
which freely works the shaft of a depending roll so that as the said carrier is
rotated the said hangers and rolls rotate therewith. The rolls are so placed that
their own weight acting on their hanger fulcrums, in conjunction with the centrifugal
force due to their rotation about the central driving shaft, presses them firmly
against the inner surface of the beforementioned horizontal grinding ring on which
they roll.
From the roll carrier depends an annular frame or casing having a similar
contour to the inner portion of the dished pan or trough, so as to leave an annular
space between them, and being provided with inclined blades or ploughs which as
the frame or casing is rotated lift the material from the trough and throw it in
front of the rolls and on to an internal cylindrical or conical screen surmounting
the horizontal grinding ring and extending to the underside of the roll carrier
plate. The finer particles passing through the meshes of the said screen fall down
through the annular space between the outer casing and the grinding ring into a
receiving chamber beneath the rolling pan or trough from which they are in turn
discharged through a delivery spout by means of a rotating pan or scraper mounted
on the driving shaft.
A. packing strip is provided to prevent the escape of the finely powdered material
between the top of the casing and the carrier plate. The roll bearings are outside
the casing so that access of dust to the same is prevented. The material to be
pulverized is fed to the interior of the mill through a central opening, or by means
of a hopper placed centrally over the driving axis and connected spirally or
otherwise so that the centrifugal action and the rotation assists the feed.

page_text: In a modification of my invention the roll hangers are pivotted nearer to the
axes of the rolls, which ensures the resultant pressure between the roll and the
grinding ring being normal or nearly so, the roller being pressed against the ring
by a spring.
Dated this 8th day of March 1893.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.
COMPLETE SPECIFICATION.
Grinding and Pulverizing Mills.
I, JOSEPH HUNT, citizen of the United States, residing in Allentown, County
of Lehigh State of Pennsylvania, United States of America Engineer, 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:-
My invention relates to that class of grinding or pulverising mills in which the
material to be ground is in a dry state and in which the grinding or pulverising
action is effected by rolls running against the inner face of a fixed ring, the objects
of my invention being to so construct a grinding or pulverising mill of this class as
to insure the effective contact of the grinding rolls with the inner face of the ring,
whether the mill is run fast or slow, to effectually prevent the escape of the finely
ground or pulverised material from the mill casing, or its access to the roll bearings,
to provide for the ready feeding of the mill, preferably by a central opening, to so
construct the apparatus as to admit of ready lubrication, and to so hang the
grinding rolls as to permit of the ready application or removal of the same when
desired and lessen the friction due to the rotation of the same on their axes.
above objects are carried out by the construction of the apparatus of which the
following is a description.
Referring to the accompanying drawings:-
:-
The
Fig. 1 is a vertical section of a grinding mill constructed in accordance with my
invention.
Fig. 2 is a plan view of the same.
- Fig. 3 is a sectional view illustrating a modification of the invention.
Figs. 4 and 5 are detached views illustrating a special detail of the invention.
Fig. 6 shows a modified mill in elevation and half in section.
Fig. 7 is a plan view of Fig. 6.
A represents the base or foundation of the mill upon which is mounted an
annular trough-like structure B supporting a ring D, an outer casing F surrounding
said ring D and structure B and said outer casing F having at the top an inwardly
projecting ring F' which overlaps the ring D.
The base structure A of the mill has a step bearing a for the lower end of a
central vertical shaft G which passes through a bearing a¹ at the top of an upwardly
projecting central portion of hub formed upon the trough structure B, and upon the
upper end of said shaft is mounted a dished plate J constituting a roll carrier, to
which are pivoted the swinging hangers K, for the shafts of the grinding rolls M
three of these being employed in the present instance although any desired number
of equi-distantly arranged rolls may be employed as desired.
The top flange of the roll carrier J is slotted for the reception of the outer
portions of the swinging hangers K, and has depending pair of lugs b, to which said
outer ends of the hangers, are pivoted, each hanger and each pair of lugs, having,
by preference, a series of openings d, to either of which the pivot pin d', can be
adapted so as to shift the fulcrum of the hanger as desired.
Each hanger K, terminates at the inner end in an enlargement K', forming a

page_text: bearing for the shaft M', of the grinding roll, and said enlarged inner portion of
each hanger is adapted to a radial recess f, formed in the dished portion of the roll
carrier J, as shown in Fig. 2, so that as said carrier is rotated the hangers K, and
the rolls M, will be caused to rotate therewith.
Each roll M, is supported vertically in its hanger K, by means of a collar secured
to the upper end of the shaft M, and bearing upon the top of the enlarged inner
end K, of said hanger, said collar being preferably formed as shown in Figs. 4 and 5,
that is to say, by means of two half collars g g', each having a flange i, adapted to
an annular groove ', formed in the shaft some distance below the top of the same,
these half collars being held together by an encircling ring h, resting upon external
shoulders h', formed on the half collars as shown in Fig. 4. Between the bottoms
of the collars and the top of the hanger K¹, are interposed one or more washers k,
preferably of antifriction metal:-
A collar of this sort can be readily applied or removed and is therefore preferable
to a single collar secured in place by a transverse pin or equivalent means.
Extending from the top of the cap ring F2, to a point close to the bottom of the
top flange of the roll carrier J are two annular screens P P', the inner screen
being perforated and the outer screen being imperforate and having also at the top
an imperforate ring m, with packing strip m', bearing against the underside of the
flange of the carrier J, the space between the two screens being in communication
with the annular space F', between the ring D, and casing F, through openings n,'
formed in the ring F2.
From the bottom of the roll carrier J, depends an annular frame S, which is
substantially similar in contour to the trough structure B, and is adapted to run
close to the bottom of the latter, said frame being provided with the usual inclined'
blades or plows S¹, which, as the frame is rotated, lift the material from the trough
and throw it up in front of the rolls M, and onto the internal screen P, which is, by
preference, inclined outward from bottom to top so that the particles projected onto
said screen will roll down the same and thus provide for a more effective sifting of
the fine particles from the coarse particles than would be effected by a vertical
screen or by a screen inclined inward from bottom to top.
The screening of fine particles from the coarse particles is also materially facilitated
by the fan-like action of the projections or pockets f, formed upon the roll carrier J,
the use of a special fan for the purpose being dispensed with.
The particles caught between the rolls M and the ring D, are crushed thereby, it
being understood that the rolls M are pressed firmly against the ring D by reason
of the centrifugal force due to the rotation of the series of rolls around the common
axis supplied by the shaft G, each roll being also caused to rotate upon its own axis
of such intimate contact with the ring D.
It will be observed that the pivot of each roll hanger K is outward beyond the
axis of the roll, so that there is a natural tendency of the roll to bear against the
ring D, independently of the centrifugal force, hence mills, especially those having
heavy rolls, can be run with good effect at low speed as is desirable in some cases.
The fine particles passing through the meshes of the internal screen P, are
discharged from the space between the two screens through the openings n, and
passage F, into a receiving chamber T, beneath the trough structure B, from
which they are in turn discharged through the spout T¹ by means of a rotating fan
or scraper s, carried by the shaft G.
The roll carrier J, has elongated openings to permit the slight vibrating
movement of the shafts M', which results in the operation of the mill, and in order
to prevent the escape of the finely powdered material through these openings each
of them is covered by a plate t¹, which fits snugly to the shaft M', and is free to
move to and fro with the same. The escape of the finely powdered particles from
the top of the mill is effectually prevented by the packing strip m' which bears
against the underside of the top flange of the roll carrier so that the mill is
practically dust tight, an important consideration in dry grinding mills of the
character to which my invention relates.

page_text: It will be noted, moreover, that the bearings for the roll shafts are entirely
outside of what may be termed the casing of the mill, so that the access of dust
to these bearings and the attendant wear and inconvenience are effectually
prevented.
In order to provide for the ready feeding of the mill I employ an axial hopper W
with spout leading outward from the bottom of the same and passing through the
bottom of the roll carrier J, at a point between the central hub of the same and the
wall of the dished portion, preferably as close to the latter as possible so that
the centrifugal action aids the flow of the material from the hopper through the
spout, the feeding device, of course, rotating with the roll carrier, but the hopper
owing to its axial position, being practically stationary so that the material can be
readily fed into the same while the mill is running.
In practice I prefer to make the feed spout Win spiral form, as shown, although
a straight spout may be used if desired.
In Fig. 3, I have shown a modification of my invention in which the inner
portions Kof the roll hangers have short arms K with lugs, w, bearing in a groove
formed in the top of the carrier J, so that the fulcrum of each hanger is closer to
the axis of the roll shaft than in the construction shown in Fig. 1, and said roll
swings outward almost in a direct line against the grinding ring. In this case also
I have shown springs a interposed between the hangers K¹ and adjustable studs
on the hub of the roll carrier so that the action of said springs supplements the
centrifugal action or the outward swing of the rolls in pressing said rolls against
the grinding ring.
In Figs. 6 and 7, I have shown a modification of the mill. in respect to the feeding
of the same.
In place of the axial hopper W with spiral feed spout W', I use the
central feed opening W10, which in some construction is preferable to the axial
hopper as feeding the mill more easily and rapidly.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The combination in a grinding or pulverising mill, of the grinding ring, a
series of rolls in contact with the inner face of said ring, a rotating roll carrier
located above the grinding ring and having a central vertical portion with radial
recesses or pockets therein, and hangers for the shafts of the grinding rolls, said
hangers being pivoted to said carrier and adapted to the pockets therein so as to
have a driving contact with the walls of said pockets, substantially as specified.
2. The combination in a grinding or pulverising mill, of the grinding ring, a
series of rolls in contact therewith, a dust proof casing for the said grinding ring
and rolls, and a rotating roll carrying structure having roll bearings wholly outside
of said dust proof casing of the mill whereby dust is prevented from gaining access
to said bearings, substantially as specified.
3. The combination of the grinding ring, the grinding rolls running in contact
with the inner face of the same, and hangers for said rolls pivoted at points outward
beyond the axial line of the rolls whereby the latter normally swing in contact
with the ring substantially as specified.
4. The combination of the grinding ring, the series of rolls in contact with the
inner face of said ring, a rotating roll carrier located above the ring, an internal
perforated and external imperforate screen mounted above the grinding ring and a
packing ring carried by said screen structure and bearing against the roll carrier
so as to form a dust proof joint therewith, substantially as specified.
5. The combination of the grinding ring, the grinding rolls, the screen above the
ring, and a rotating roll carrier having projecting pockets which serve as vanes to
direct a current of air through the screen, substantially as specified.
6. The combination in a grinding or pulverising mill, of the grinding ring, the
grinding rolls rotating in contact with the inner face of said ring, the pivoted
hangers for the shafts of the rolls, and a roll carrier having on its outer portion

page_text: depending arms in which are mounted the pivot pins for the rolls-shaft hangers,
substantially as specified.
7. In a grinding and pulverising mill the employment of a central opening as
arranged and shown in Figs. 6 and 7, and substantially for the purpose set forth
and specified.
Dated this 8th day of December 1893.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents: