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Патент USA US3042332

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July 3, 1962
Filed May 27, 1955
4 Sheets-Sheet 1
Z;I3WI%6v wpmy?x?
July 3, 1962
Filed May 27, 1955
4 Sheets-Sheet 3
Zaren ?. ,SymonS
July 3, 1962
Filed May 27, 1955
4 Sheets-Sheet 4
United ‘States Patent 0
1 r.
Patented July 3, 1962
Like parts are indicated by like symbols throughout the
Loren G. Symons, North Hollywood, Calif., assignor to
Nordherg ‘Manufacturing Company, Milwaukee, Wis.,
a corporation of Wisconsin
speci?cation and drawings.
Referring to the drawings, and in considering an im
proved ball mill adapted to carry out my improved
method, I illustrate, as a matter of example, a mill hav
ing the following main components:
Filed May 27, 1955, Ser. No. 511,665
A generally indicates a normally ?xed base mounted on
1 Claim. (Cl. 241--175)
any suitable support.
_My invention relates to an improvement in grinding
B indicates a sub-frame or sub-base or rotor or table
methods, and in mechanism for practicing such methods. 10 which, as will later appear, is rotatably mounted upon the
‘ Onepurpose 18 to provide an improved grinding method
1n which a charge of grinding balls is employed with
greater efficiency.
Another purpose is to provide such a method and mech
amsm in which the charge of grinding balls is effecting
a grinding action substantially continuously during the
presence of the material to be ground in a grinding zone.
Another purpose is to provide an improved method in
whlch a given charge of balls is employed with a sub
stantlally greater output per time period than is possible
with methods and mechanism previously known.‘
Another purpose is to provide a grinding method and
mechanism in which centrifugal force is controllably em
Another purpose is to provide an improved method and
apparatus for imparting to the balls or elements of the
ball tcharge an optimum grinding path and grinding move
men .
. Another purpose is to provide an improved ball mill
1n whlch a given output of ground material can be pro
duced in a mill of substantially smaller size than known
mills of equivalent output.
Another purpose is to provide a method and mecha
base A for rotation about a preferably vertical axis X.
C generally indicates a ball track or grinding chamber
assembly or bowl or retainer in which a charge of balls
performing the grinding is contained, and within which
it moves to perform its grinding function in relation to
the material to be ground.
D generally indicates feeding means for feeding the ma
terial to be ground into the ball chamber or bowl C.
The bowl C is rotatably mounted on the sub-base B
and rotates about an inclined axis Y, which, as shown,
for example, in FIGURE 2, intersects the above men
tioned axis X, the point of intersection being indicated as
at Z in FIGURE 2.
Before describing the details of my method and of the
particular means herein illustrated for carrying it out, I
wish to emphasize that I obtain my results by controlling
and relating a group of factors ‘which, for convenience, I
shall call “variables.”
Considering ?rst the augmented “gravity” to which the
charge of balls and the material to be ground are sub
jected, I provide the necessary outward thrust against the
retainer by rotating the ball-containing chamber or track
trolled and related as to obtain an improved grinding
Another purpose is to provide an improved method or
mechanism in which the thrust or force to which the ma
about its axis Y at a rate sufficient to obtain the desired
outward centrifugal thrust of the charge and of the ma
terial undergoing crushing against the inner ‘wall or sur
face of the bowl. The rate of rotation ‘will, of course,
vary with different sizes of mill. A satisfactory outward
thrust may, for example, be of the order of eight times
terial is subjected substantially exceeds gravity, and in
gravity. However, this may be widely varied and is given
‘msm in which a plurality of variable factors are so con
which, in addition to a rotation effective to subject the 40 as a practical example and not as a matter of restriction.
Of course, normal gravity still acts downwardly.
charge and the material to more than gravital thrust, an
If I were merely ‘to rotate a charge of balls and mate
additional motion ‘or motions are employed to impart a
grinding movement to the charge.
Another object is to provide an improved grinding
mill and method in which all the grinding media are grind
ing at all times.
Another object is to obtain a radical increase in the
material ground per horsepower.
Another purpose is to provide an improved method or
mechanism in which the charge is subjected, during ro
tation about a predetermined axis, to additional forces
effective to impart relative movement to the individual
balls of the charge.
rial undergoing grinding about a given upright axis, I
would obtain little or no grinding e?iciency, because the
charge and material would tend to “freeze” against the
bowl or retainer in an undisturbed equilibrium position,
and would thereafter rotate in :unison with the bowl,
with little or no relative movement of the various particles
and balls involved and thus with no grinding at all. In
50 order to obtain the necessary action of the charge of balls
I subject the charge to other forces creating the desired
grinding. In the mill herein described I obtain this ac
tion as follows.
While rotating the ball housing or bowl at uniform
Other purposes will appear from time to time in the
course of the speci?cation and claim.
55 angular velocity about its inclined axis Y, I also rotate
‘the sub-frame or base B about its axis X. I ?nd it ad
I illustrate myrinvention more or less diagrammatically
vantageous that rotation of the respective elements about
in the accompanying drawings wherein:
their axes should be in opposite directions. As a result
FIGURE 1 is a perspective view;
of this simultaneous reverse rotation about dilferent but
FIGURE 2 is a vertical axial section, on an enlarged
60 intersecting axes I give the charge of balls a grinding ac
tion between the balls and the bowl, and between indivi
FIGURE 3 is a diagrammatic illustration of the con
dual balls. It will be understood that I may vary the angu
tour of the ball track or chamber, as shown in FIGURES
lar relation between the two axes. I may also vary the
1 and 2;
rotational speed of the sub-base B about the axis X, and
FIGURE 4 illustrates a variant form of the track in
65 may independently vary the rate of rotation of the bowl
which it is elongated along its axis of rotation;
or housing C about the axis Y. These factors may vary
FIGURE 5 is another diagrammatic showing in which
with the radius of the bowl, and the size of the bowl
the ball track is radially elongated or enlarged;
may be widely varied, to grind more or less material.
FIGURE 6 is a vertical axial section of another form
I may also vary the shape or form of the bowl. I il
of my invention; and
lustrate, in FIGURES l and 2, ‘a bowl which is generally
FIGURES 7, 8 and 9 diagrammatically illustrate cross
spherical and concentric with the intersection Z between
sections of the load at various positions of the bowl.
the axes X and Y. In FIGURE 4, I diagrammatically
illustrate an axial departure from sphericity, and in FIG
URE 5, I illustrate diagrammatically a radial departure
may all be removed and replaced by others of slightly
different diameter, thereby controlling the relative rota
from sphericity.
tional speeds about the two axes.
In connection with the structure as shown, I illustrate
As a matter of fact, I ?nd that I can
substantially vary the contour of the track C while main
taining a practical operation of my method. I may even
employ conic ‘faces.
a bowl or grinding chamber wall 50 which is generally
spherical and formed about the center Z where the axes
X and Y intersect. Under some circumstances, I ?nd it
Referring to the speci?c structure of FIGURES 1 and
preferable to vary from this sphericity. I illustrate,
2, I may employ any suitable frame elements 1, which
diagrammatically, in FIGURES 3, 4 and 5, a possible
may, for example, be I-beams or channel beams, suitably
connected, for example, by a top plate 2 and transversely 10 range of variations. In FIGURE 3 the track 50' is shown
as generally spherical. In FIGURE 4 I illustrate it as
extending angles 3 and 4. The top plate 2 is shown as
varying from this sphericity by an axial elongation. In
apertured as at 5, and as associated with a discharge
FIGURE 5, on the contrary, I depart from sphericity in
chute shown as including an inclined plate 6 and an up
per inclined continuation or extension thereof 7. Any
material received on the plate portions 6 or 7 will flow
downwardly over the lower discharge edge 3 to any suit—
able receiving or disposal means, not herein shown. I
illustrate an upper circumferential ?ange or wall 10 which
may receive a suitable housing 11 having a cover plate 12
apertured as at 13 to permit the entry of any suitable
downspout or feed chute 14.
Considering now the supporting and driving means for
the rotated portion ‘of the structure, I illustrate a nor
the direction of an increase in radius about the central
part of the track. It will be understood that the grinding
chamber or member can be widely varied from the spheri
cal, a spherical or generally spherical shape not being
Regardless of the contouring of the bowl itself, I ?nd
it advantageous to have an upper end member 51 which
may include a central, generally conic wall 52 terminat
ing in an aperture 53. The parts are so proportioned that
at no position is the wall 52 or the aperture edge 53 in
mally ?xed bearing sleeve 24}. This sleeve extends to
contact with the downspout or feeding member 14. I
and may form part of any suitable gear housing having a 25 illustrate the bottom of the ball track or ‘bowl or grinding
bottom member 21 and side member, or members 22,
chamber as closed by a bottom member 55 which is con
shown as provided with a connecting top plate or ?ange
nected by the sleeve portion 56 with the shaft 44. In the
23. It will be understood that the member 26} and its as
particular form of my device shown in FIGURE 2, I
sociated gear housing 21, 22, 23, may be mounted on or
illustrate, also, an outer sleeve, or axial discharge tube,
suitably secured to the base frame, for example, by at— 30 or dam 60, 61. It will be understood that I prefer to have
tachrnent to the transversely extending angles 3 and 4.
this dam adjustable as to height. For example, the upper
24 generally indicates a shaft to which is keyed a suit
section 61 may be removably secured and may readily be
able driving element or pulley 25 which may be driven
removed when the feed distributing plate 70 is removed
by belts 26 from any suitable motor means or power
from the top of the shaft 44. When the upper sleeve ex
source, such as the motor 27. The shaft 24 is mounted
tension 61 is in position the ground particles flow over its
in suitable bearing assemblies 28 and 29 and carries gears
upper edge in the direction of the arrows of FIGURE 2.
or pinions 30, 31, of different diameters. The pinion 30
I do not illustrate any speci?c means for removably
meshes with the gear 33 on the vetrical shaft 32 mounted
supporting the sleeve extension 61, since it will be under
for rotation about the axis X. It rotates within a hollow
stood that any suitable means for varying the height of
sleeve 34 rotatable in bearing assemblies 35 and 36 within 40 the discharge lip 61a may be employed. It will be under
the ?xed sleeve 20. The hollow sleeve 34 is driven
stood, also, that the sleeve portions 60 and 61 may be
through the gear 37 in mesh with the upper and smaller
apertured intermediate their ends, or may ‘be entirely dis
pinion 31 of the shaft 24. 38 and 39 are any suitable
pensed with. In the structure as shown in FIGURE 2,
bearing assemblies interposed between the inner shaft 32
however, the material which passes over the discharge lip
and the outer hollow shaft 34. It will be understood that,
?ows downwardly through the tube or sleeve 60, to any
in response to the above described drive, they are rotated
suitable discharge aperture or apertures, such as 62, 63.
simultaneously, but at different rates of rotation, in re
If the members 60 and 61 are dispensed with, the open
sponse to rotation of the shaft 24. Mounted on and pref
ings 63 do not have to be provided with any surrounding
erably unitary with the hollow rotated sleeve or shaft 34
duct walls 63a, such as are shown in FIGURE ‘2. It will
is the sub-base or cross-head 40.
In response to or in 50 be understood, also, that the location of the discharge
unison with the rotation of the hollow sleeve or shaft 34
aperture or apertures and their shape may be varied,
depending upon the needs of a particular installation or
of a particular material to be ground.
In FIGURE 6, I have shown a variant form of mill
fore rotatable within the cross-head 40. I illustrate the »" having generally upright and inclined axes X ‘and Y inter
cross-head 40 as, for convenience, having an upper por
secting at the grinding chamber’s center Z. The basic
tion or assembly 42 which extends upwardly as the hol
parts or elements are broadly similar to those of FIG
low sleeve 43. Rotatable within it is the shaft 44 which
URE 2, and include a normally ?xed base A’ supporting a
rotates about the axis Y. This shaft is mounted for ro
sub-frame or rotor B’ with a ball track or grinding cham—
tation with the ball track element C, or, rather, the ball 60 ber C’ and a material feeding means D’, all ‘disposed gen
track element C rotates with and as a result of the ro
erally in the same relationship as in FIGURE 2.
tation of the shaft 44. 45 indicates a suitable bottom
The base A’ is shown as including a gear box 71 which
bearing assembly between the sleeve 43 and the below
supports a generally upright post or shaft 72 rigidly ?xed
described ball track, and 46 is a suitable upper bearing
or wedged by a tapered portion 73 in a box or journal 74
assembly. The bevel pinion 47 at the lower end of the 65 by a suitable nut 75 or the like.
shaft 44 meshes with the bevel pinion 41 at the upper end
A bearing assembly 76 is shown as ?xed around a suit
of the shaft 32. In response to rotation of the shaft 24
ably shouldered portion 77 of the post and carries suit
it will be understood that the cross-head 40 is rotated
able gears or pinions 78 and 79 which are bolted or other
about the axis X, and the ball housing assembly C is
wise suitably interlocked. The lower gear 79 meshes with
rotated in an opposite direction of rotation about the 70 a pinion 80 keyed to an input shaft 81 which is supported
axis Y. I may employ any suitable means for varying the
on a suitable boss or journal 82 by appropriate bearings
relative speeds of rotation about the two axes. Since the
83 with a suitable cover plate 84.
details do not of themselves form part of this inven
The upper pinion or gear 78 meshes with a pinion 85
tion, I do not show them. It will be understood, for ex
?xed on an inclined shaft 86 rotatably supported by
ample, that the gears or pinions 30, 31, 33, 37, 41 and 47 75 suitable bearings 87 and 88 in the sub-frame or rotor B’.
the cross-head 40 rotates about the axis X. Within the
hollow of the cross-head 40 I illustrate the bevel pinion
41 keyed to the upper end of the solid shaft 32, and there
The sub-frame or rotor is suitably counterweighted
such as at 89 and ‘90 and is rotatably mounted on the
supporting post or shaft 72 by suitable bearing units 91
and ‘92. A seal 93 is effected between the rotor or sub
While it is convenient to use a vertically axised machine,
even a horizontally axised machine is operable.
Whereas, in FIGURE 2, I illustrate a means for con
otherwise suitably connected to the counter-weighting at
trolling the level of escape of the ground particles, the
sleeve 60, 61 of variable height, it will be understood
that the sleeve may be completely or partially omitted.
For example, I may employ a coil spring or conical rings
96 which meshes with a pinion 97 on a second input shaft
‘98 ‘which is rotatably supported in a suitable boss or
the balls of the charge with the ground material. Where
frame and a cover 94 on the gear box. The rotor may be
driven by a suitable pinion or ring gear 95 bolted or
journal 99 by bearings 100.
The housing 101 surrounds the bowl or grinding cham
ber and supports the feed means or chute D’. The hous
ing 101 may be removably mounted as shown in FIGURE
as a discharge controlling means to prevent the escape of
10 as a coil spring is satisfactory as a means to prevent or
limit such escape, any other suitable means may be em
Whereas, in FIGURE 2, I illustrate a three-part ball
track member, including the elements 51, 50 and 55, I
15 illustrate, in FIGURE ‘6, a single ball track element or
tegral part of the gear box or base.
The bowl or chamber C’ is shown as generally spherical
member. I ?nd it important that the ball track member
in :FIGURE 6 although it could be one of the other
be readily removable and replaceable. For example, in
6 or it can be permanently connected or formed as an in
forms previously shown. A conical wall 102 or the like
extends downwardly from the upper opening and is
removably connected by bolts or the like.
the structure of FIGURE 6 the ball track member C1
can be removed unitarily and quickly from the hub struc
ture or shaft with which it rotates. It is shown as having
The inclined shaft 86 has a central disc or shoulder por
an inwardly, conically surfaced ?ange 106 opposed to and
tion 103 with a plurality of legs or spokes 104 connected
conforming to a centering ‘?ange 105 mounted on the cen
tral disc or hub 103- of the inclined shaft 86. The bowl
or ball track member C1 can readily be removed upon
to a ring 105 which ?ts into or against a shoulder or ?ange
106 formed on the bottom of the ball track. The upper
end of the inclined shaft carries a ‘feed distributing plate 25 removal of the distributing plate 107 and the collar 114
107 which opposes the inlet feed or chute D’.
through which a downward thrust is exerted against the
The discharge opening 108 in the bottom of the bowl
cage or screen structure, generally indicated at 109, and,
may be covered by a screen type medium 109 which in
thus, against the lower edge of the ball track member.
cludes a plurality of ring members 110 decreasing in
When the ball track member is worn in use it may thus be
diameter upwardly and each resting on or connected to a 30 bodily upwardly removed and replaced.
plurality of spoke-type members 111. Sleeve 112 with a
The use and operation of my invention are as follows:
?ange 113 is forced down against the spokes by a collar
Stated broadly, my method includes using: a con?ning
member 114 which is threaded on the inclined shaft at
member or bowl, within which the load of balls and mate
rial undergoing grinding is con?ned. The rotation of this
-In this form the basic operation is much the same as in 35 member about its axis creates the grinding force or pres
that of FIGURE 2. Any suitable drive can be connected
sure between load and bowl, and between the balls of
the load. The gyration of the bowl about a central point
to one or both of the two input shafts, such as separate
motors or the like. The sub-frame or rotor is rotated in
the opposite direction from the bowl or grinding chamber.
Suitable lubrication can be provided through the center
shaft at 116.
The bowl or chamber, while shown as a
single piece, may be in halves or several portions, either
causes movement of the load in relation to the inner sur
face of the bowl, and, at the same time, causes relative
movement of the elements of the medium.
Thus the
simultaneous rotation and gyration of the bowl creates,
throughout the entire load, pressure and motion sufficient
to grind the hardest particle.
welded or bolted together.
The device can be used as a batch grinder, either dry or
A centrifugal force to arrange the balls and material
around the bowl or ball track is set up by rotating the 45 wet, and it may be used as an air swept grinder by ap
chamber about the inclined axis Y. The rotor is at the
propriate air connections of any suitable type, the details
of which, for clarity, have not been shown, as I consider
same time rotated in the opposite direction about the
them conventional.
vertical axis X at a speed su?icient to create motion be
While the shape of the bowl may be varied, I show it
tween the balls and the bowl, and between the elements
50 herein as generally spherical.
of the load.
I claim:
One effective way of operating the device, as shown
In a grinding mill, a base, a sub-base mounted thereon
in the various ?gures, is to rotate the bowl and rotor at
for rotation about a generally upright ?rst axis, a hollow
suitable rotational speeds but in opposite directions.
mounted on a shaft extending upwardly ‘from the
Each element of the ball and material load will be sub
55 subebase for simultaneous rotation about its axis inclined
jected to lifting and lowering cycles at a rapid rate.
It will be realized that whereas I have described a prac
at a predetermined ‘angle to and intersecting the ?rst axis,
the bowl having a top opening surrounding the ?rst axis
in all bowl positions, means disposed in the ?rst axis to
tical method, and have described and shown a practical
structure for carrying it out, nevertheless many changes
deliver a generally constant stream of material to be
may be made in method steps and characteristics, and in 60 ground normally through said top opening into the interior
size, shape, number and disposition of parts of the illus
of the bowl in the general direction of the intersection of
trated structures without departing from the spirit of my
the two axes, a body of grinding media in the interior
invention. I therefore wish my description and drawings
of the bowl, means located entirely below the open top of
to be taken as in a broad sense illustrative or diagram
the bowl to drive said rotary sub-base and said bowl shaft
matic rather than as limiting me to my speci?c structure. 65 for rotating the bowl simultaneously about both axes at
For example, the grinding member need not be spherical
a speed e?ective to maintain the media and the material
or generally spherical but can be made in a wide variety
undergoing grinding centrifugally against the inner surface
of elongated shapes. It will be understood, for example,
that the particular mode of mounting the moving parts
of the bowl with a thrust of the order of several times
gravity, and at the same time to impart to the media and
and the particular means for driving the moving parts are 70 material a substantial wave-like movement across the
illustrative rather than restrictive. I may, for example,
equator of the bowl, and a generally annular concave dis
employ individual motors for rotating the shafts 32 and
charge -at an end of the bowl, surrounding but radially
44 in the form of FIGURE 2, rather than to drive them
spaced from the bowl axis, formed and adapted to permit
from gearing from a single motor, as shown herein. 75 the escape of ground material along and from the inner
surface of the bowl, while resisting the passage of the
References Cited in the ?le of this patent
Vose _________________ -_ Dec. 4, 1855
Wegrnann ____________ __ June 25, 1889
Pendleton ____________ __ Aug. 5, 1902
Pendleton _‘_ __________ __ Feb. 24, 190-3
Weston _______________ __ June 8, 1954
Limb _________________ __ July 9, 1957
Germany ____________ __ Nov. 11, 1938
Great Britain _________ __ Nov. 27, 1953
Symons _______________ __ Feb. 6, 1951
Youngnickel _________ __ July 26, 1955
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