IMPROVEMENTS IN GRINDING MILLS
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by the said Louis Gathmann at the
Office of the Commissioners of Patents on the 14th March 1882.
LOUIS GATHMANN of the City of Chicago, State of Illinois, United States of
America, "IMPROVEMENTS IN GRINDING MILLS,"
This Invention relates to apparatus in which discs are used for grinding or
reducing grain and other materials. It has for its object to provide means for
subjecting the grain or other material passed between the discs to a practically
uniform and determinate action therefrom, whereby the product is made more
regular than heretofore as regards the size of its particles, and whereby all portions
thereof may be equally preserved from overheating or from other harmful effects
of too long subjection to the grinding action. To these ends the disc faces, and
particularly one of them, are formed or constructed in a novel manner as hereinafter
set forth.
In those forms of dress heretofore given to millstones or grinding discs there is
nothing so far as I am aware to prevent some portions of the material operated
upon from being retained much longer than other portions between the grinding
faces. This is one of the serious objections hitherto urged against the disc form of
grinding face as compared with the roller or cylinder form.
In the case of two cylinders or of a cylinder and concave the extent of the
grinding action is practically the same upon all parts of the mass subjected thereto.
That is to say in reducing wheat for example by cylinders or by a cylinder and
concave, each kernel of the mass of grain passes over the same extent of surface,
and remains subject to the grinding action the same length of time, practically as
every other kernel of the mass. This has not been true of disc grinding faces as
heretofore constructed, the open furrows on the one hand allowing the grain or
middlings to escape at any time, and no provision being made on the other hand
[Pains 6d1

page_text: to prevent the same substance from passing over several succeeding lands, and
thus to be too long or too severely acted upon. The disc form of mill bas,
however, many important advantages over the cylindric forms mentioned, parti-
cularly with regard to cost and more easy management. It has therefore been
sought in this invention to obviate the objections mentioned by establishing the
same conditions in the discs that are present in the said cylinder forms of mill.
In carrying the said invention into practice the discs may be mounted in any
approved framework to run either with a vertical or with a horizontal axis, and
should be housed and otherwise fitted and accompanied after the usual manner of
discs in a disc mill.
In a vertical axis arrangement of the discs the upper disc has a central aperture,
through which the material to be operated upon is fed between the discs, and a
depressed portion or bosom surrounded by the annular working face, which is
preferably not more than from 3 to 6 inches in width, and is dressed according to
the work to be done as will be hereinafter explained.
The lower disc also has a central depression or bosom and a marginal working
face corresponding in radial width with that of the upper disc. When the two
discs are mounted in working relation, the faces are parallel, whether plane or
conical or concave and convex.
.
While either disc may be rotated in an operative machine I prefer that the
under disc shall be the runner. In the bosom of the runner are fixed a number of
wings or raised flanges which are inclined or set on a draft suitably to throw the
material to be ground outward when the runner is in motion. Grooves or furrows
may be used instead of the raised flanges. The working face of the lower disc is
formed as follows; furrows are made leading outward from the bosom either
radially or on a draft as may be preferred, and terminating a short distance inside
the periphery of the disc: They may therefore be called "blind" furrows. These
furrows are in sectional form, like the furrows of an ordinary mill stone; that is
they have a gradual upward and rearward slope to the level of the face. Alternating
with the said furrows I provide deep recesses which open broadly in the periphery
of the disc, but terminate at their inner ends in the face a short distance outside
the inner edge of said face, or outside the raised margin of the bosom. The sides
of said recesses are abrupt or nearly vertical and said sides diverge in the lines
where they cut the face so as to leave lands in said face of substantially equal
width throughout their length. The several land faces of the lower disc are also
of substantially equal width one with another.
In the operation of the discs when mounted as described the material to be
operated upon is thrown outward by the wings, and enters the furrows. Having
no other escape it thence passes over the lands, and the product falls into tho
recesses. The rear walls of these recesses being abrupt as stated, said product
cannot again rise to the face, but is, by centrifugal action thrown out of said
recesses at their open ends in the periphery of the disc. The lands being of
substantially equal and uniform width, as described, the grinding action is
practically the same in extent of time and space upon each and every part,
fragment or kernel passed through the machine, and the limit of this action may
obviously be predetermined in fixing the breadth of the lands.
The nature of the reducing action of the discs will depend upon the nature of
the working faces; that is to say of the furrows and lands in the lower disc and
of the face in the upper disc. For the purpose of a first reduction of grain or for
splitting the grain through the crease, the grooves and lands of the disc should be
smooth. With the lower disc so constructed, and for this particular effect the
upper disc has cut in its face a series of fluted or rounded grooves of uniform
width, and depth, and located close to each other at their inner ends. The purpose
and effect of these rounded grooves when opposed to the smoothly finished lower
disc are to catch the whole grain kernels as they rise on the incline of the furrows,
to turn them in such direction that they will pass the lands practically parallel
therewith, and to positively retain them until they have passed the lands, and

page_text: have been split by pressure thereof. To this end the rounded grooves are section-
ally less than a half circle so as to hold down the kernels therein retained against
the opposing land, and they are of such breadth as to allow the kernels to spread
therein in the act of splitting. For ordinary wheat the grooves may be, say,
about /ths of an inch in breadth at the surface of the disc, and say about 1/18 inch
in depth. Plain faces intervening between the adjacent grooves perform no work,
but are made smooth in order that a kernel caught between said faces and the
incline of the furrows in the opposite disc may slide upon the former until reached
and taken up by the next groove.
The importance of at once discharging the half kernels after splitting the grain
as effected by the contraction in the lower disc is apparent such splitting being
solely for the purpose of detaching the germ and crease impurities which it is
desirable to do without the production of flour.
For subsequent reductions of the grain the lands of the lower disc may, if
preferred, be ridged or dressed in any suitable manner. In the upper disc a form
of dress may be used consisting of a series of shallow radial grooves of any desired
firmness.
For the later operations upon middlings or for their reduction to flour I prefer
to employ porcelain or stone for the upper disc. Certain well known kinds of
stone and porcelain will in their natural wear constantly present a rough or
granular surface well suited to the reduction of middlings. When opposed to this
grit the lands of the lower disc are preferably perfectly smooth or slightly
roughened.
I do not wish to restrict myself to any particular character of surface for the
lands or to those forms of dress or surface in the opposing upper disc which are
herein described.
The furrows may be closed at their outer ends by means of a metal ring which
is shrunk or otherwise secured in place after the furrows have been finished out.
By this means an emery wheel may be used to polish the furrows throughout their
length and the lands may be made straight and of accurately uniform width from
end to end. The furrows may be cast to terminate inside the periphery of the
disc and have their land edges curved at their outer ends as they appear after
being finished out by an emery wheel. In order to give uniform width to the
lands throughout their length in this case the land walls of the recesses are corre-
spondingly curved at their outer ends. While this is productive of perfect
accuracy in the width of the lands substantial accuracy so far as results are
concerned will be obtained if the recess wall is made straight.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Louis Gathmann in the Great Seal Patent Office on the
14th September 1882.
LOUIS GATHMANN of the City of Chicago State of Illinois United States of
America "IMPROVEMENTS IN GRINDING MILLS
"
This Invention relates to apparatus in which discs are used for grinding or
reducing grain and other materials. It has for its object to provide means for
subjecting the grain or other material passed between the discs to a practically
uniform and determinate action therefrom, whereby the product is made more
regular than heretofore as regards the size of its particles, and whereby all portions
thereof may be equally preserved from overheating, or from other harmful effects
of too long subjection to the grinding action. To these ends the disc faces and
particularly one of them, are formed or constructed in a novel manner as
hereinafter set forth.
In those forms of dress heretofore given to millstones or grinding discs, there is
nothing, so far as I am aware, to prevent some portions of the material operated
upon from being retained much longer than other portions between the grinding
faces. This is one of the serious objections hitherto urged against the disc form of
grinding face as compared with the roller or cylinder form.
In the case of two cylinders, or of a cylinder and concave, the extent of the
grinding action is practically the same upon all parts of the mass subjected thereto.
That is to say in reducing wheat, for example, by cylinders or by a cylinder and
concave, each kernel of the mass of grain passes over the same extent of surface
and remains subject to the grinding action for practically the same length of time.
This has not been the case with disc grinding faces as heretofore constructed, the
open furrows on the one hand allowing the grain or middlings to escape at any
time and no provision being made on the other hand to prevent the same substance
from passing over several succeeding lands, and thus being too long or too severely
acted upon. The disc form of mill has however many important advantages over
the cylindric forms mentioned, particularly with regard to cost and management.
By this invention I obviate the objections above mentioned and establish the same
conditions in the disc form of mill that are present in the said cylindric forms
of mill.
In the accompanying Drawings:
Figure 1 is a view of the principal parts of a grinding mill, having a vertical
axis and containing my improvements, in which the curb the upper disc, and part
of the feed tube are in central vertical section and the remainder in elevation.
Figure 2 is a perspective view of the lower disc constructed in accordance with
my invention.
Figure 3 is a plan of a part of a disc having a simple form of dress, and adapted
to be used for general purposes in connection with the disc shown in Figure 2.
Figure 4 shows the upper disc provided with a special form of dress, suited to
splitting lobated grain through the crease.
Figure 5 is a vertical section through the working faces of the discs shown in
Figures 2 and 4 and illustrative of their action in splitting grain.
Figure 6 is a plan of a part of a porcelain disc intended to be used with the disc
shown in Figure 2 for the reduction of middlings to flour.
Figure 7 illustrates a modification of the disc shown in Figure 2
According to this invention the discs may be mounted in any approved framework
to run either with a vertical or with a horizontal axis, and should be covered and
otherwise fitted in the usual manner,

page_text: In a vertical axial arrangement as here represented A is the upper disc and bed
and B the lower disc and runner rotating in the direction indicated by the arrows,
Figures 1 and 2.-The said discs may be of any suitable size or material.
The upper disc or bed A has an eye O through which the material to be operated
upon is fed between the discs and a depressed portion or bosom C surrounded by
the annular working face D. The said face is preferably not more than from
three to six inches in width, and is dressed according to the work to be done as
will be hereinafter explained.
The lower disc or runner B also has a central depression or bosom E and a
marginal working face F corresponding in radial width with that of the disc A.
When the two discs are mounted in working relation to each other the faces D
and F are parallel, whether plane conical, or concave and convex.
While either disc may be adapted to be rotated I prefer that the under disc
shall be the runner.
In the bosom E of the runner B are fixed a number of
wings or raised flanges e which are inclined or set on a draft, suitably to throw
the material to be ground outward when the runner is in motion but grooves
or furrows may be used instead of the raised flanges e. The working face F of
the disc B is formed as follows, furrows; G G are made leading outwards from the
bosom E either radially or on a draft, as may be preferred, and terminating a short
distance inside the periphery of the disc. They may therefore be called "blind
furrows," These furrows are in section similar to the furrows of an ordinary mill
stone; that is they have a gradual upward and rearward slope to the level of the
face F. Alternating with the furrows G are the deep recesses H H which open
broadly in the periphery of the disc, as shown, but terminate at their inner ends in
the face F a short distance outside the inner edge of the said face, or outside the
raised margin of the bosom E.
The sides of the recesses H are abrupt or nearly vertical, and the said sides diverge
in the lines where they cut the face F so as to leave lands I in the said face of
substantially equal width throughout their length. The several lands of the disc A
are also of nearly the same width throughout. their length.
In the operation of the discs when arranged as described, the material to be
operated upon is thrown outward by the wings e and enters the furrows G.
Having no other means of escape, it thence passes over the lands I where it is
reduced, the product then falls into the recesses H. The rear walls of these recesses
being abrupt, as stated, the said product cannot again rise to the face F but is, by
centrifugal action thrown out of the said recesses at their open ends in the periphery
of the disc. The lands being of substantially equal and uniform width, as described,
the grinding action is practically the same with regard to time and space upon each
and every part, fragment or kernel passed through the machine, and the extent of
this action may obviously be predetermined in fixing the breadth of the lands I.
The nature of the reducing action of the discs will depend upon the nature of the
working faces; that is to say, of the furrows G and lands I in the disc Band of the
face D in the disc A. For the purpose of a first reduction of grain, or for splitting
the grain through the crease, the grooves and lands of the disc B should be smooth
and the upper disc dressed as shewn in Figure 4. The latter has cut in its face D
a series of fluted or rounded grooves d of uniform width and depth, and located
close to each other at their inner ends. The purpose and effect of these rounded
grooves d when opposed to the smoothly finished disc B is to catch the whole
grain-kernels as they rise on the incline of the furrows G to turn them in such
direction that they will pass the lands practically parallel therewith, and to positively
retain them until they have passed the lands I and have been split by the pressure
thereof.
To this end the rounded grooves d are sectionally less than a half circle, so as to
hold down the kernels therein retained, against the opposing land, and they are of
such breadth as to allow the kernels to spread therein in the act of splitting. This
action is illustrated in Figure 5 which also shows the discs set at a distance apart
less than the diameter of the grain, measuring from the bottom of the grooves d to

page_text: the top of the opposing lands I.-For ordinary wheat the grooves may be, say, about
three sixteenth's of an inch in breadth at the surface of the disc, and, say about
one sixteenth of an inch in depth. Plain faces & intervening between the adjacent
grooves d perform no work, but are made smooth, in order that a kernel caught
between the said faces and the incline of the furrows G in the opposite disc, may
slide upon the former until reached and taken up by the next groove.
In Figure 5 k k represent whole kernels of wheat and half kernels which
have passed the lands I and in passing them have been split through the crease.
The importance of at once discharging the half kernels, after splitting the grain
as effected by the construction shewn in the disc B is apparent, such splitting being
solely for the purpose of detaching the germ and crease impurities, which it is desirable
to do without the production of flour.
For subsequent reductions of the grain the lands I of the disc B may if preferred,
be ridged or dressed in any suitable manner. In the disc A a form of dress shewn
in Figure 3 may be used consisting of a series of shallow radial grooves of any
desired fineness.
For the latter operations upon middlings, or for their reduction to flour, I prefer
to employ porcelain or stone for the disc A as shown in Figure 6 wherein I have
sought to represent the working face D as presenting the natural grit of a ground
porcelain surface. Certain well known kinds of stone and porcelain will, in their
natural wear constantly present a rough or granular surface, well suited to the
reduction of middlings. When opposed to this grit, the lands I of the disc are
preferably perfectly smooth or only slightly roughened.
I do not restrict myself to any particular character of surface for the lands I or
to those forms of dress or surface in the opposing disc A which are herein shown or
described.
In Figure
the furrows G G are closed at their outer ends by means of a metal
ring R which is shrunk or otherwise secured in place after the furrows have been
finished out. By this means, an emery wheel may be used to polish the furrows
throughout their length, and the lands I may be made straight and of accurately
uniform width from end to end. In Figure 7 the furrows G G are cast to terminate
inside the periphery of the disc, and have their land edges curved at the outer ends,
as they appear after having been finished out by an emery wheel. In order to give
uniform width to the lands throughout their length, in this case, the land walls of
the recesses H are correspondingly curved at their outer ends. While this is
productive of perfect accuracy in the width of the lands, substantial accuracy so
far as results are concerned, can be obtained if the recess wall is made straight.
Having thus fully described my said invention and the manner of performing
the same I wish it understood that I claim in a mill for grinding corn and similar
substances.
First: The combination with an opposing disc having a relatively plain working
face, of the disc B provided in its working face with alternating feeding furrows G,
lands I, and recesses H having abrupt rear walls and discharge openings, substantially
as, and for the purposes, set forth.
Second: The combination, with an opposing disc having a relatively plain,
working face, of the disc B having on its working face furrows G leading from the
bosom outwards and terminating near the periphery, recesses H having abrupt rear
walls and extending inwards from the periphery nearly to the bosom, and intervening
lands I of practically uniform width, substantially as, and for the purposes, set
forth.
Third The combination, with an opposing disc, of the disc B having the feeding
furrows G the discharging recesses H and the intervening lands I of practically
uniform width arranged alternately as shown, all substantially as, and for the purposes
set forth.
Fourth: The combination, with the disc B having furrows G discharging
recesses H and intervening lands I arranged alternately as shown, of the opposing
disc A having a relatively plain and uniform surface, whereby all parts thereof

page_text: present the same acting surface in opposition to the lands I substantially as
described.
Fifth The combination, with the disc B having the alternating furrows G lands
I and recesses H arranged as shown, of the opposing disc A having grooves of
rounded form, substantially as described, and for the purposes set forth.
Sixth-The combination, with the dise B having the alternating furrows G
lands I and recesses H arranged as shown, of the opposing disc A of stone or
porcelain, and having a granular surface, substantially as described and for the
purposes set forth.
In witness whereof I the said Louis Gathmann have hereunto set my hand
and seal this Thirtieth day of March in the year of our Lord One thousand
eight hundred and eighty two.
LOUIS GATHMANN. (L.S.)