Improvements in Grinding Mills.
Year: 1899

page_text: Date of Application, 6th Oct., 1899-Accepted, 11th Nov., 1899
COMPLETE SPECIFICATION.
Improvements in Grinding Mills.
We, EMIL ROBERT DRAVER and HENRY CHRISTOPHER DRAVER, both of Win-
chester, in the State of Indiana, United States of America, Millers, 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 relates to grinding mills, of that type wherein a screw or pro-
peller co-operates with a resistance plate or block, to effect the grinding action;
and it has for its object to provide an improved machine of this class, with a
view of securing an increased working capacity.
To this end the said invention consists of the novel devices and combinations
of devices hereinafter described and defined in the claims.
The invention is illustrated in the accompanying drawings, wherein like
characters indicate like parts throughout the several views:-
Fig. 1 is a perspective view, illustrating the improved machine.
Fig. 2 is a side elevation partly in vertical section, with some parts broken
away, illustrating the said machine, and Fig. 3 is a detail in transverse vertical
section, taken approximately on the line of Fig. 2.
The numeral 1 represents a pedestal casting which supports the machine. To
the pedestal 1 is bolted or otherwise rigidly secured a casting 2. The casting 2
is of suitable form to afford a long bearing 3 for the pulley sleeve 4, and has
formed integral therewith a cylindrical casting 5, open at its outer end and
constituting the feed trough or casing for the grinding screw or propeller, as
will later more fully appear. The casing 5 is also provided with a neck or
extension 6, which serves as the feed hopper. To the outer and otherwise open
end of the casting or annular trough 5 is bolted or otherwise rigidly secured a
tapering annular collar or truncated cone 7, which, as will hereafter appear,
co-operates with the screw or propeller, and serves as the so-called "resistance
plate or block." On its inner surface, this annular resistance plate 7 is formed
or provided with a series of radial flights or web-like projections 8, for a purpose
which will hereafter appear. At its contracted outer end, the said annular
resistance plate 7 opens into a discharge box 9, which, as shewn, is cast integral
therewith, is formed with a bearing 10, and has an opening at its top which is
shewn as closed by a removeable lid or cover 11.
The longsleeve 4 heretofore noted as being mounted in the bearing sleeve 3
At its outer end, the
of the casting 2, is provided with a driving pulley 12.
sleeve 4 is formed with longitudinal grooves or slots 13, for a purpose which
will presently appear.
The bearing sleeve 4 and the bearing 10 of the discharge box 9 stand in axial
line, and in these aligned parts 4 and 10, a shaft 14 is mounted. Near one end,
the shaft 14 is provided with projections formed by roller-equipped studs 15,
which work one in each of the slots 13 in the outer end of the bearing sleeve 4,

page_text: and together therewith constitute a clutch. In this manner, the said shaft 14
is caused to rotate with the sleeve 4, while, at the same time, it permits the
desired axial movement, as will hereinafter appear.
To the shaft 14, within the feed trough or casting 5, is rigidly secured a
propeller hub 16, having spiral blades 17, the diameters of which are nearly
equal to the internal diameter or wall of the said trough or casting .5. As
shewn, the propeller 17 is in the form of a double screw. The hub 16 is provided
with an extension 18, which flares slightly outward and terminates at its outer
end, approximately in line with the outer contracted extremity of the tapered
annular resistance plate 7, at which point it is of such diameter that it normally
nearly, but not quite, closes the passage through the said resistance plate, the
said part 18 thus serving as a gate thereto.
To a horizontal bracket 19 rigidly secured to the flanges of the castings 1
and 2, and projecting toward the right, under the shaft 14, is fulcrumed a
bent lever 20, which is provided on its lower or horizontal arm with a suitable
adjustable weight 21, which it will be noted by reference to Fig. 1, is adapted
to work through an opening 22 formed in the standard 1. The upper end of
the lever 20 has a convex flattened head 23 which bears against a cap 24 fitted to
the outer end of the shaft 14. The cap 24 has a concave face, which engages and
embraces the head 23 of the lever 20, and is thereby prevented from turning
with the said shaft 14. Hence, the shaft 14 is under yielding pressure from the
weight 21 to move toward the left, and force the propeller blades 17 toward
the stationary resistance plate 7.
With the construction above described, the grinding action will be readily
understood from the following statement. Assuming the proper stock to be
supplied through the food hopper 6 to the feed trough or case 5, and the pro-
peller to be under rotation at the proper speed, the grinding action will take place
under the co-operation of the propeller blades 17 and the resistance plate or
ring 7.
As the said shaft 14 is under strain from the weight 21 to move toward
the left, the gate or extension 18 of the propeller hub 16 will slide through the
opening in the resistance plate or ring 7, and the stock will be fed by the
blades 17 and held under yielding pressure against the inner surface of the said
resistance plate or ring 7. The non-rotary resistance plate 7, with its radial
flights or webs 8, prevent the stock, which is being ground, from rotating over
the inner surface of the resistance plate or ring 7. Hence, under the rotation
of the propeller, the stock will be ground by the rubbing action of the propeller
blades, and the rubbing action of the particles of stock on each other. Otherwise
stated, the propeller blades will rub against the stock under vielding pressure,
and the rotary motion of the particles of stock, when thus held under pressure,
between the propeller blades and the resistance plate or ring 7, makes the particles
rub against each other, thereby producing the grinding action.
The stock will be gradually worked through the annular discharge openings
formed between the outer end of the hub extension or gate 18 and the opening
in the contracted outer portion of the annular resistance plate or block 7.
Obviously, as the shaft is moved toward the right, so as to carry the outer
extremity of the hub extension or gate 18 inward or away from the opening
in the said resistance plate 7, the annular discharge opening between the said
parts is enlarged or increased, so as to give a more rapid discharge of the ground
stock from the mill.
By shifting the weight 21, the propeller blades may he set to work toward
the resistance plate 7 under any desired pressure.
This renders the mill, to a large extent, self-adjusting to the proper grinding
action, regardless of whether or not the feed of the stock from the hopper 6
is properly graduated. If a large quantity of stock is supplied to the feed
trough, the propeller will simply yield backward or move away from the
resistance plate 7. thereby increasing the size of the annular discharge opening,
as above described, for adaptation to the increased quantity of stock, while con-

page_text: tinuing to grind under the same pressure as if a smaller quantity of stock were
being acted on.
The discharge gate might take other forms than that shewn, as long as the
gate is automatically adjustable with the propeller shaft; or the discharge
opening itself might be indirectly varied by the longitudinal movement of the
propeller shaft or hub. This machine is especially designed for action on what
is known to the trade as dust middlings," but may, however, be used on other
forms of stock after one or more breaks or reductions have been made.
66
It will be further understood that that this class of grinding mills is especially
intended for operation on comparatively soft stocks, which cannot be handled
with equally good effect in a roller mill. Such soft stocks, when subjected to
the rollers, are simply mashed or flattened.
Under the treatment peculiar to this grinding mill, such soft stocks may be
ground into granular condition, so as to have much the same appearance as
hard stock, when treated by a roller mill.
By actual usage, the efficiency of the mill herein described, for the purposes
had in view, has been demonstrated. As compared with a roller mill, for action
on the same kind of stock, such as dust middlings, for example, it has been
demonstrated that a small mill of this type, costing only a small fraction of the
cost of a roller mill, will do an equal amount of work, and give a product of
much higher grade.
This is thought to be the first grinding mill of the screw or propeller type,
wherein the propelling blades radiate from a solid hub or shaft, as distinguished
from being formed by a twist in the shaft, auger-like, and wherein the hub or
shaft extends through the resistance block or plate, which co-operates with the
propeller or screw, whether the said resistance block or plate be stationary or
movable lengthwise of the shaft. The said resistance plate or block must, how-
ever, be a non-rotary one, and must not turn with the shaft.
This machine is also thought to be the first wherein the grinding screw or pro-
peller is held under yielding pressure to move toward and from the resistance
plate or block which co-operates therewith.
This machine is also thought to be the first, wherein the discharge opening
from the mill is automatically varied in size, under the longitudinal movement
of the grinding screw or propeller, thereby rendering the mill self-adjusting to
irregularities in the feed, and to different conditions in the stock.
From the foregoing statements, it will be obvious, of course, that the invention
herein described is capable of a considerable range of modifications in structure,
without departing from the essential features of the invention.
Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed we declare that what
we claim is :-
1. A grinding mill wherein the grinding screw or propeller has an extended
hub or shaft which passes through a suitable non-rotary resistance plate, the
said parts being so arranged that a yielding action is afforded between the
propeller and the resistance plate.
2. A grinding mill wherein the grinding screw or propeller is so held, under yield-
ing pressure, as to be capable, of moving toward and from a suitable non-rotary
resistance plate, the discharge opening of the mill being automatically varied
in size under the longitudinal movement of said propeller.
3. A grinding mill wherein the grinding screw or propeller is held under
yielding pressure so as to be capable of moving toward and from a suitable non-
rotary resistance plate, the said resistance plate being provided with an opening,
while the said propeller is provided with an extended hub which serves as a
gate for co-operation with the said opening in the resistance plate, for the
purpose of automatically varying the size of the discharge opening of the
grinding mill under the longitudinal movement of said propeller.

page_text: 4. A grinding mill, wherein the grinding screw is subject to yielding pressure
and co-operates with a suitable resistance plate which is provided with flights for
preventing the rotation of the stock with the propeller, substantially as
described.
5. A grinding mill, wherein the grinding screw or propeller is so mounted,
under yielding pressure, as to be capable of moving toward and from a non-
rotary resistance plate, and wherein the propeller shaft is clutch-connected to a
combined bearing and driving sleeve, with freedom for sliding motion there-
through while being rotated thereby, substantially as described.
Dated this 6th day of October 1899.
ABEL & IMRAY,
Agents for the Applicants.