IM- PROVEMENTS IN THE MANUFACTURE OF MIDDLINGS AND FLOUR, AND IN APPARATUS OR MACHINERY THEREFOR."
Year: 1879

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake, & Co.,
Patent Agents, Southampton Buildings, London, for the Invention of "IM-
PROVEMENTS IN THE MANUFACTURE OF MIDDLINGS AND FLOUR, AND IN
APPARATUS OR MACHINERY THEREFOR." A communication from abroad by
Thomas Wallace, of Joliet, Illinois, United States of America, Millwright and
Engineer.
Sealed the 23rd December 1879, and dated the 28th October 1879.
COMPLETE SPECIFICATION filed by the said William Robert Lake at the
Office of the Commissioners of Patents on the 28th October 1879.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN THE MANUFACTURE OF
MIDDLINGS AND FLOUR, AND IN APPARATUS OR MACHINERY THEREFOR." A
communication from abroad by Thomas Wallace, of Joliet, Illinois, United States
of America, Millwright and Engineer.
In the manufacture of flour from cereal grains by the older methods, it was sought
to accomplish the result by a single operation of grinding. The grain was therefore
subjected to the grinding action until as much as possible thereof was properly
reduced. As a result of long continued grinding, some portion of the interior
substance was heated and injured, and a considerable part of the integunent or
bran was comminuted equally with the flour, so as to be inseparable therefrom.
Recognizing the objectionable effects of heating and of the presence of commi-
nuted bran in the flour and its products, manufacturers in the more modern methods
of milling have sought to remedy the evils by "gradual reduction," or in other
words, by a series of partial and less severe grindings alternated with separations of
the bran and inferior products of the inner grain substance from the cleaner portions
of the latter.
As such separations are practicable only when the granulations of the inner grain
substance are coarser than flour, it has become an object in the advanced art of high-
grade flour manufacture to make as large a proportion of such coarse granulations

page_text: as possible in the first instance, which, after being purified, are reduced to flour.
There has thus arisen in said art the distinct preliminary product consisting of such
coarser granulations, and known as middlings.
A principal object of the Invention herein described is to make a larger part of
the grain into middlings than has heretofore been done. This I accomplish by a
method which will be hereinafter fully set forth, whereby the inner structure of the
grain is broken down or disintegrated through its natural cleavages, which give
granular form to its particles, and by rubbing or grating the same off the bran by
the tractive action of granular surfaces suitable for the purpose, as will be explained.
Not only do I thus make more middlings and less flour, but I also make the lessened
proportion of flour of granular form or quality.
Since all processes and appliances employed for the purification of middlings are
troublesome and expensive, and not always wholly effective of their purpose, another
principal object of my Invention is to make the middlings and its inevitably atten-
dant flour more free from bran impurities in the first instance, and thus obviate the
necessity of purification. In other words, I seek by my Invention rather to prevent
than to cure the evil of comminuted bran in the food product. This I accomplish
by fixedly holding the bran out of reach of the action of the granulating and
stripping surfaces while the food snbstance is being removed therefrom.
For these purposes I employ two sharply rough or granular cylindric surfaces,
arranged opposite and near each other, and moved inwardly and downwardly
towards their proximate line at materially different velocities, each one of which
surfaces is adapted at any point in its area to imbed itself by pressure in the
integument of a grain fragment, so as to draw the fragment off any overlying
fragment similarly held by the opposite cylindric surface, and to draw it along upon
said opposite surface, and thus to rub or grate off the food substance of both
fragments in granular form by their action upon each other, and by the action of
the cylindric surfaces upon them.
In the accompanying Drawing,-
Figure 1 is a side elevation of my improved mill.
Figure 2 is an end elevation thereof, with the front cross beam removed.
Figure 3 is an end elevation of one of the cylinders when made of stone, showing
devices by which the cylinder is secured to the shaft; and
Figure 4 is a central sectional view of the cylinder secured to the shaft.
Figure 5 is intended to shew the progress of the grain when admitted whole in
its passage through the space between the cylinders, and will be referred to in
describing the action of the cylinder surfaces, which are themselves not easily
capable of graphic illustration.
A represents a strong frame, consisting of two parallel lateral uprights rigidly
united by suitable cross beams not seen in the Drawing. B and B are two prefer-
ably equal cylinders, say 18 inches or upwards in diameter, and of any desired
length, mounted upon the frame A by means of the central shafts S, which have
bearing in the boxes J. These boxes are adapted to slide a short distance horizon-
tally in their seats upon the frame A, and are confined by the cap-plate C, bolted as
shown to the standards J, which rise from the frame A. The cylinder B is brought
to position and secured by the set screws a, a, threaded through the standards J¹,
and arranged to bear against the boxes in the direction of their movement through
the interposed plates j. The cylinder B¹ is similarly controlled by the screws a¹
and a, but for the purpose of more convenient adjustment, the outer screws all are
carried to the front of the machine through bearings b, and there provided with
hand wheels C¹ and the strong springs are inserted between the boxes J and the
inner standards J'. These springs operate to constantly throw the cylinder outwards
against the screws a", so that these screws only need be manipulated in making the
nice adjustment required of this cylinder. After the adjustment is made the stop
screws a¹ may be set up to hold the boxes fixedly in place. The working pressure
being outward upon the cylinder shafts, the boxes J are divided so that one half of

page_text: each box supports the shaft on its under and outer surface, as shewn. This portion
of the box is provided with the removable brass d, or is otherwise specially fitted to
accurately and durably support the shaft.
His a housing which covers the cylinders, and with the casing G, G¹, forms an
inclosure for the cylinders and other working parts of the mill, for the purpose of
excluding dirt from the product. M is a central elevated hopper, communicating
through the housing with the cylinders. It is provided with the feed-roller I and
with the adjustable slide 8, which is controlled by the screws c, provided with hand
wheels h and passing through eyes f. The grain from the hopper is discharged
between the converging plates g, g, secured to the under surface of the housing, and
arranged to convey the grain well down between the cylinders, and to deliver the
same as nearly as may be directly above or at the point at which it is grasped by
said cylinders. E and E' are two cylindric brushes supported in contact with the
cylinders B and B' respectively, as shown by the adjustable shaft bearings e in the
brackets p. W is a screw conveyor arranged centrally beneath the cylinders Band
B¹ in the trough T.
The several working parts are given suitable motion as follows:-P is a driving
pulley fixed to the shaft S of the faster cylinder B. R and R' are gear wheels
fixed to the shafts of the cylinders B and B¹ respectively, being of such relative size
as to give the requisite difference in surface speed to the two cylinders, of which
relative speed more will be said hereinafter. The machine is driven to rotate the
cylinders downwardly and inwardly towards their proximate line, as indicated by
the arrows. From a smaller pulley Q, on the shaft of cylinder B, the adjacent
brush E is driven by the belt v, and the other brush E¹ is driven by a crossed belt w
from the first brush, the shafts of said brushes being provided with pulleys p¹ for
this purpose. The surfaces of each brush and cylinder in contact are therefore
moved in opposite directions, and any material detached by the brushes is thrown
inwardly.
The feed-roller I is also operated from the pulley Q through the roller pulley O,
which is of proper relative size to give suitable speed of motion to the feed-roller.
For the purpose of securing a perfectly positive and reliable motion of the feed-
roller I prefer to use a chain u in connection with pulley surfaces adapted thereto,
such as are commonly used to prevent the chain from slipping. In order to arrest
the feed without stopping the mill the pulley O is made loose on the roller shaft t,
and movement of the latter is obtained by a clutch of which K represents the
gland sliding on the shaft t, and rotated with it by means of a short feather or stud
in the shaft that rises into a longitudinal groove in the gland. The gland is slid
by the arm N, pivoted at n, the lower end of said arm running in the central
annular groove of the gland K in the usual manner. The meeting faces of the
gland and pulley-hub are notched to engage when the gland is thrown outward,
and when engaged the roller is set in motion in the proper direction to carry the
grain out beneath the slide 8. For the purpose of suddenly and certainly arresting
the feed-roller at any time the inner end of the sliding gland K is also notched to
engage with the stationary bearing of the shaft t. The fragmentary piece x, shown
pivoted to the upper end of the arm N, represents a rod connecting with the
arms N of other similar machines, so that the feed of several mills, set side by side,
may be simultaneously controlled from a single point. F represents a fly wheel on
the faster shaft S; and L, a vertical conveyor, connecting with, and, if desired,
operating the horizontal conveyor W.
The cylinders B and B are usually made of stone, and to secure them perfectly
and permanently to the shafts I have employed the means illustrated by Figures 3
and 4, and now to be described. B in said Figures represents the stone, which is
first roughly prepared in cylindrical form and provided with a central opening
through it for the free admission of the shaft $; C" is a heavy cast iron gland
having marginal projections c¹ and a central aperture adapted to closely fit the
shaft S. One such gland is set in each end of the cylinder and securely leaded in

page_text: place, the shaft S being inserted and keyed at m while this is being done in order
to hold the two parallel, and otherwise in proper position. After securing the
glands to the .cylinder the latter is mounted in a lathe and turned up to form
and size, and the ends are faced off to receive the heads H¹. For the purpose of
saving labor the central portions of the cylinder ends are left depressed by the
hammer, so that the skirt only requires to be faced, and the heads H¹ are given
only marginal bearing thereon, as shewn in Figure 4. The heads are secured to
the stone by means of the plugs P¹, which are also leaded into the stone and are
tapped to receive the bolts b. The heads are also secured to the shaft by set
screws or keys, and the hubs are dressed to fit closely between the bearings or
boxes J so as to have no material end motion in the machine. The final or
working surface of the cylinder, which requires to run with the utmost truth
in operation, is usually given after the heads H¹ are in place and with the cylinder
shaft in its proper bearings.
In the operation of the machine herein described, the cylinders are set parallel
to and near each other but never in contact. Whole grain fed from the hopper is
received between the cylinders, and is first crushed so as to break down the inner
structure and disrupt the integument, and thereafter drawn apart and stripped as
will be further described, the product being discharged into and carried out by the
conveyor beneath the cylinders or otherwise if preferred.
Cylinder mills having many of the general features of construction above
described have been used before; but the cylinder surfaces employed in my machine
and for my purposes are not of the heterogeneous character indifferently suited to
the objects of cylinder mills as hitherto constructed and used. These surfaces in
my machine need to be in their structure of a uniformly finely and somewhat
sharply rough character, as nearly like the fracture of marble or sand stone as they
can be made under the tool by which they are turned to give them the true
cylindric form required. They are intended to imbed or impress their numerous
prominences in the outer surface of the bran or grain integument sufficiently to
fixedly hold such integument from sliding thereon so long as pressure is continued
upon the other surface of the grain fragment by the opposite cylinder, and to
uniformly support all parts of the bran sheet of such fragment. They are also
intended to so engage or act upon the food substance of a grain fragment so held
by the opposite cylinder as to rub, grate or crumble such substance off the fragment
in granular form when that part of the grain is brought into contact therewith.
For these purposes they require to have a continuous or unbroken surface of the
grangular character described, since any point in either cylinder may be called upon
to either thus imbed itself in and support in proper position a flattened fragment
of grain or to detach the middlings from a fragment so held. A cavernous material
like French burr stone will therefore not answer the purpose, nor will any material
having smooth spots that will slip on either surface of the fragment, for in that
case the middlings will not be stripped off the integument by the differently
speeded surfaces, but will be simply compressed and pulverized, which is an effect
to be avoided in the practice of my method.
The required surface may be artificially produced by a composition of small
angular fragments or grains of suitable substance, say of silicious sand, emery, or
corundum of Number 40 or thereabouts, as known in the trade, united to a matrix
of proper cementing material moulded in cylindric form and finally trued in a
lathe with a diamond or other proper tool. The matrix being softer than the
imbedded grains will wear away and expose the angular prominence of the grains
until the matrix is beyond the reach of further attrition. A surface so formed will
preserve its character indefinitely, and may be restored to cylindrical truth whenever
it is necessary by the lathe and tool as at first. Cylinders possessing the required
characteristics of surface may also be made of marble, sandstone, or other substances
having uniformly close texture, which after dressing by the diamond or other tool
will present a continuous homogeneous surface of angular fracture or cleavage,

page_text: Marble does not however possess sufficient endurance to make its use advantageous
for my purpose.
The requisite characteristics of surface may also be produced by sand-blast upon
substances not otherwise capable of assuming the same, such, for example, as steel,
chilled iron, and the like. I do not therefore propose to limit myself to the use of
any particular substance or material, but only to the continuous angular or granular
forin of surface capable of holding a flattened bran sheet by impression therein as
described, and of grating or stripping off the food substance by tractive action
thereon.
I will now proceed to more fully set forth the action of the cylinders by reference
to Figure 5 of the Drawing, which shews a kernel of wheat admitted whole between
the cylinders. B is the faster and B' is the slower cylinder.
It is advantageous to perform the operation of granulating wheat by my machine
by a succession of similar operations. The grain may be previously crushed or
flattened if desired by means of a simple crusher consisting of a pair of plain evenly
speeded crushing rolls, but I prefer to perform the crushing in the mill herein
described which has both granular quality and unequal speed of cylinder surface
for the sake of obtaining the drawing action upon the inner particles of the wheat
in the first instance instead of simple compression, because the latter tends more to
pulverization (as distinguished from granulation) than does the former.
In Figure 5 the whole kernel is seen at 1, where it is caught between the
cylinders. At 2 it is shewn crushed, having been carried forward into a space narrow
enough to break down its structure and rupture the integument. Up to this point
(2) the berry, if received horizontally, has been rotated as well as compressed. At
this point the bran is flattened and disrupted practically into two separate sheets,
each firmly impressed upon the adjacent cylinder and baving no union with the
other sheet except through the disintegrated mass of food substance between them.
From this point forward each part of the integument will be carried forward inde-
pendently of the other by the cylinder surface that holds it at 3, therefore that
fragment adhering to the faster cylinder B is in advance of the other, and a portion
of the food substance of both sheets has been exposed and is being grated or rubbed
off the mass by the opposite cylinder surface.
At 4 and 5 the two bran sheets are shewn to be entirely separated and the still
adhering food substance upon each is fully exposed to the grating action of the
opposite cylinder; at 6 the advanced bran sheet is shewn falling from the cylinder,
having been released from pressure as it has emerged from the neck of the passage
between the cylinders. If by chance it still adheres to the cylinder it is detached
by the brush E and falls into the conveyor beneath. The retarded sheet soon
follows.
In rubbing upon each other as well as in rubbing on the opposite cylinder the
food-substance generally broken in crushing is further divided into granules through
their natural cleavages. A very small proportion will be in the form of granular
flour, but by far the greater portion will be in the form of coarser granulations or
middlings.
When the grain is admitted whole as above described I prefer that the action may
be as gentle as possible thereon in the first operation, therefore it is better that the
difference of speed for this operation be no more than, say, 4 to 3 for 18 or 20-inch
cylinders, and that the cylinders be set at such a distance apart as to only fairly
flatten the bran into sheets and to detach only the originally central portion of the
food-substance of the berry. The middlings and flour from this operation are
screened out from the portions still adhering to the bran by means of a revolving
reel which gives gentle friction upon the fragments among themselves. Preferably
the reel will be clothed with two or more grades of screening cloth, and thus also
separate the middlings from the flour at the same time. The portions containing
bran sheets pass over the tail of the reel and are sent to a second cylinder machine
like the first wherein the cylinders are set nearer to each other than in the first

page_text: operation. The action upon the partly denuded bran is in all essential respects
precisely the same as in the case above set forth. It is plain that the flattened
sheets will arrange themselves edgewise between the cylinders, and that they will
severally adhere to the cylinders by the bran side only, since that side alone presents
material resistance to the grating action of the granular cylinder surface or gives a
hold to such surface. There will be no regularity in the relative positions of the
several fragments of grain as they are received by the cylinders in the second or
any following operation, but those fragments which chance to overlie will be drawn
upon each other and off into contact with the opposite cylinder surfaces, practically
as already set forth above, and in general the fragment will be stripped more or less
according to the distance at which the cylinders are set from each other. The
second stripping is succeeded by a separation of the middlings and flour from the
bran-bearing portions of the grain as before, and the latter is again passed through
cylinders set still closer. These operations may be repeated to any desired extent,
though I find that from three to five passages including the first are sufficient to fit
the bran for the bran-cleaning machine. Different qualities and conditions of grain
however require somewhat different treatment in this respect, and also in respect
to the difference in speed of the cylinder surfaces, less violent action being better in
the case of the harder and drier wheats than in the case of wheats of softer character
or conditions.
To obtain the best results in the case first described, wherein whole wheat is fed
to the cylinders, the rate of feed should be so regulated that the grains will enter
between the cylinders at a little distance apart in order that they may have room
to spread upon the cylinder surfaces in the act of crushing, without crowding one
another (as such crowding would prevent the bran sheets from flattening wholly so
as to be out of reach of the opposite cylinder), and thus permit the comminution of
the, bran.
It is obvious that in the practice of the method and in the operation of the
machine above described the bran sheets may by proper adjustment of the feed-
roller and the cylinders be held out of reach of the cylinder opposite that to which
they adhere, and that practically all the food substance may be removed without
seriously disturbing the bran.. Whatever bran is detached will be principally from
the torn edges of the bran flakes, and these particles will be usually of such size as
to be easily removed from the middlings.
The food product of the above described method and apparatus is, as stated, in
granular form, and contains but a small proportion of flour. The flour produced is
not only less in relative quantity than has heretofore been made in granulating
wheat, but it is far superior to the ordinary "first flour" or incidental flour product
made in the manufacture of middlings by other appliances and methods.
I have spoken of the character of the surface required for my cylinders as
distinguished from the surface belonging indifferently to the various cylinder mills
hitherto in use. . Not only is the surface described requisite, but it is also necessary
that said surfaces have such a material difference of speed as will draw the over-
lying fragments of. grain off each other and upon the cylinder surfaces as described.
What this difference will be cannot be arbitrarily stated, since it will vary with the
diameter of the cylinders, but it may be proximately given as varying, say, from
1/4 to 1 to 4 or 5 to 1 for cylinders both 18 inches in diameter, or, say, from a
difference sufficient to carry originally coincident fragments about one half their
length off each other (in order to carry a central granule out from between them) to-
a difference sufficient to wholly and widely separate the fragments. The surface 5
speed of the faster cylinder may be as high as from, say, 500 to 750 feet per minute,
variable according to quantity and condition of the wheat and the kind of result
desired.
"
The slowest speed and the lowest ratio of difference in speed should be employed
in the first operation, upons whole wheat, since the bran not being flattened or s
divided when first seized the imbedding action is for an instant delayed; so when

page_text: the grain is received vertically, and until impressed so as to be held, there may be
a slight and brief grating of the grain surface. This is so slight, however, that it is
not found to be necessary to use any devices for the purpose of feeding the grains
horizontally, as may obviously be done. Generally in determining the precise rate
and difference of speed to be given to the cylinder surfaces several things must be
taken into account, such as economy of working or capacity, as well as the nicer
questions of quality in the product. Discrimination will also be made with regard
to the kind of result wanted. Thus the gentle action suggested for the first opera-
tion upon whole wheat is found to affect the quality and quantity of the "first
flour," and not materially the quality of the middlings; that is to say, by using
both a high rate and a high difference of speed the capacity of the mill is greatly
increased and the quality of the purified middlings is sustained, but the quantity of
the middlings is perhaps slightly lessened and the purity of the "first flour" is
lowered. Circumstances may make the advantage of increased capacity outweigh
the disadvantage of this change in "first flour," and vice versa. The operator will
by the employment of change gear wheels soon learn what variations are advan-
tageous for the special result he seeks to obtain.
A marked advantage of my improved method and apparatus over others hitherto
employed for making middlings is that as many middlings may be made thereby
from soft as from hard wheat, a result never before obtained by any method or
machine.
.
In the foregoing description of apparatus I have specified cylindric surfaces as
the agents by which my process is performed. Cylinders are doubtless best adapted
to effect said process, besides being the most simple and convenient form in which
the desired relations of such surfaces may be obtained. An operative mill may,
however, be made by arranging a disc to rotate in a vertical plane proximate to a
horizontal cylinder placed opposite the downward moving face of the disc. The
practical objections to this form of apparatus are obvious, but it may be made to
embody the essential conditions of my method and machine, and therefore to
fall within my Invention; said conditions being the peculiar surfaces described,
coupled with the material inequality of speed given them, as set forth.
I am aware that middlings have heretofore been reduced to flour by the action
of porcelain rollers revolving at different speeds, but such rollers have been dressed
with smooth surfaces, and were therefore incapable of the action herein-described
and claimed.
Having thus fully described the said Invention as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that I claim,
First. The method or process of making middlings from grain, namely, by first
crushing the grain so as to break down the interior structure and disrupt and flatten
the bran into sheets, and subsequntly rubbing or grating off the interior substance
from the bran-sheets while the latter are fixedly held by their outer surfaces,
substantially as described.
Second. The method or process of granulating the inner substance of grain, and
separating the same from the bran, namely, by first crushing the grain so as to
break down its interior structure and disrupt and flatten the integument into
sheets; secondly, holding the fragments fixedly by their bran surfaces, and rubbing
off a portion of the food substance while so held; thirdly, separating the detached
food substance from the partially denuded bran-flakes, and thereafter repeating the
operations of holding and stripping the bran sheets and separating them from the
detached granules, once or more than once, as may be required, substantially in
the manner and for the purpose set forth.
Third. In an apparatus for the production of middlings from grain, the cylinders
B and B' adapted to be set close to each other and not to touch, each having a
continuous sharply rough or granular surface capable of imbedding itself in the bran
surface of a grain fragment, as set forth, and so connected as to rotate inwardly and

page_text: downwardly towards their proximate line at materially unequal velocities, whereby
grain admitted between them will be disrupted and fragments will be held by the
bran surfaces, and drawn upon and from each other, and their food substance
stripped from them, substantially as described.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Twenty eighth day of October, in the year of our Lord
One thousand eight hundred and seventy-nine.
W KOB LAKE. (L.S.)