IMPROVEMENTS IN ROLLER MILLS FOR THE PRODUCTION OF FLOUR AND IN APPARATUS TO BE USED FOR DETERMINING THE RELATIVE SPEEDS AND DIMENSIONS OF THE GRINDING PROVISIONAL SPECIFICATION
Year: 1882

page_text: LETTERS PATENT to John Auguste Arnold Buchholz of Vauxhall in the
10
County of Surrey Engineer for an invention of IMPROVEMENTS IN ROLLER
MILLS FOR THE PRODUCTION OF FLOUR AND IN APPARATUS TO BE USED FOR
DETERMINING THE RELATIVE SPEEDS AND DIMENSIONS OF THE
GRINDING
PROVISIONAL SPECIFICATION left by the said John Auguste Arnold
Buchholz at the Office of the Commissioners of Patents on the 1st May 1882.
JOHN AUGUSTE ARNOLD BUCHHOLZ of Vauxhall in the County of Surrey
Engineer "IMPROVEMENTS IN ROLLER MILLS FOR THE PRODUCTION OF FLOUR
AND IN APPARATUS TO BE USED FOR DETERMINING THE RELATIVE SPEEDS AND
DIMENSIONS OF THE GRINDING SURFACES."
The quality of flour or its market value is to a considerable extent governed by
the proportion of bran (in a powdered condition) contained therein and this
reduced bran is the inevitable product of every grinding mechanisin known to this
date, when employed on bran producing substances.
To diminish the production of such powdered bran, I formerly proposed to
concentrate into two grindings all the pressure usually expended in four or five
required in the reduction of wheat roughly into its constituents of bran and flour,
or flour particles in a semi-ground condition.
I have now discovered that a pair of rollers may be so speeded to operate on
grain as to ensure that practically no rubbing shall occur between their grinding
surfaces and the bran surface which rubbing is the origin of bran powder and I
am thus enabled to secure a result which is tantamount to the simultaneous
decorticating and grinding of the grain.
The rollers I so speed as to cause one of the rollers to roll out the bran of the
grain against the other roller while the grinding or reduction proceeds at such a
modified rate that the pressure of the flour forming portion of the grain is at every
point just sufficient to maintain the contact of the rolled out bran with the surface
of the slower rotating roller.
In order to attain this result I so proportion the speeds of the two rollers that
the point on the faster roller where the bite of the grain takes place shall reach the
plane of the axes of the rollers by the time that the rolled out bran carried by the
slower roller enters that plane.
To make this more clear let it be assumed that the point of first contact of the
faster roller with the seed, passes through a distance equal to 8 in order to reach

page_text: the plane of the axes of the rollers and that the rolled out bran represents a
distance equal to 5, then the distance which the first point of contact of the seed
with the slower roller travels will be. equal to 3 or thereabouts while the point of
contact of the quicker roller with the seed is reaching the plane of the axes of the
rollers.
I do not limit myself to the diameter of rollers used or to the use of rollers of
the same or of different diameters as any variation in their diameters may be
adopted, provided the relative surface speeds of the two rollers is so proportioned
as to ensure the above named result. The grinding may if desired be completed
by one or by several operations, according to the setting of the rollers but the
speed of grinding must be reduced in proportion to the completeness of grinding
required to be effected.
This will not however affect the ratio of speed which ratio is determined by the
character of the grain.
As the ordinary roller surfaces are usually too smooth to produce the necessary
grip on the grain it will be generally necessary to corrugate them. The best
corrugation is that which leaves a flat surface on the top of each ridge and has a
shallow groove with gently inclined sides, as the bran cannot then sink far over
the ridges without finding support at the bottom of the groove. In this wise the
fluting, with a suitable size of roller, will not endanger the integrity of the bran
or germ and will give the maximum of grip for a minimum of normal pressure.
As in my improved roller mill a large amount of pressure has to be exerted
which rapidly destroys ordinary bearings I propose to mount the roller axles in
the following manner.
Keyed to the roller axles are anti friction wheels designed in the proportion
required for the differentiated velocities of the two rollers. These wheels turn in
open bearings so as to present portions of their peripheries to contact with rotating
antifriction surfaces. The bearings of the one roller will be fixed and those of the
other capable of self adjustment.
Between these wheels I mount on a rocking bar which has its fulcrum in the
plane of the roller axes, a pair of antifriction wheels which are intended to press
against the wheels on the axles of the rollers and adjust the distance between the
rollers, a worm and sector on their equivalent being used for rocking the arm into
and holding it in its adjusted position.
In the plane of the axes of the rollers I provide an adjustable screwed pin to
the head of which is hinged a pair of arms carrying antifriction wheels that bear
upon the antifriction wheel of the fixed roller.
Circumscribing the group of wheels is an antifriction ring which bears upon the
periphery of the wheel of the adjustable roller and also upon the peripheries of the
wheels carried by the pair of hinged arms.
By tightening up a nut on the screwed pin which carries these arms the
antifriction wheels of the arms will be drawn nearer to the plane of the axes of
the rollers and will thereby tighten the grip of the ring.
The whole of this arrangement I enclose in a lubricating tank formed in the side
framing, using stuffing boxes where needed, to prevent the escape of the lubricant.
By thus fitting both ends of the mill little more pressure need be put upon the
mechanism than is required for the work and the proper lubrication of all the
working parts is ensured.
For the convenience of tightening the rings at the opposite sides of the mill
simultaneously I may connect the pins together by a cross bar and put the
adjusting pressure on the centre of this bar. This arrangement applies also to
roller mills generally.
To determine the ratio of speed of the rollers for a given quantity of grain I
employ a testing apparatus which I will now proceed to describe.
The apparatus consists mainly of two thin rotary discs simulating a pair of
grinding rollers the action of which it is intended to test.
These discs I arrange to test on dead pressure and also on graduated elastic

page_text: pressure and I provide for varying the speed of rotation of the two discs and for
observing the action of the discs on the grain while grinding.
The width of the discs will equal the thickness of any one grain of the species
to be ground their diameters being proportioned to obtain a proper nip of the grain
at the distance from the plane of axis above indicated. One disc is mounted on a
shaft fitted in fixed bearings and the other on a shaft mounted on adjustable
bearings carried by a pair of bars sliding in guides bolted to the main frame.
These bars are coupled together by a cross piece mounted on the end of a screw
working in a nut in the form of a hand wheel with a protruding boss, which turns
in a fixed bearing on the frame of the apparatus. By turning this nut, the
distance required between the two dises, may be determined with nicety and two
change hand-wheels are provided, one with a boss having two flanges for deter-
mining the distance adjustment of the movable disc under dead pressure, the other
with one flange only to fix the distance beyond which under graduated elastic
pressure the two discs cannot be drawn together-In connection with the graduated
elastic pressure test and by means of ropes or chains over suitably placed guide
pulleys, weights are attached to the cross piece. A belt is thrown over loose
pulleys on the two disc shafts and is carried over a tension pulley.
This tension pulley is carried on the short arm of a lever having its long arm
weighted to give the necessary tension to the belt. The weight is hung on a
sliding carrier to allow this tension to be varied at will.
If now the tension pulley lever be weighted so as to produce more pressure than
is required for grinding and if such a number of weights be placed on the cross
piece chains as to balance the pressure exerted by the weighted tension pulley, the
number of weights which have to be removed from the cross piece chains to
produce effective grinding, will indicate the pressure then exerted on the grain
with sufficient accuracy for practical purposes after deducting loss through friction
which is ascertainable by well known calculus.
The differentiated speeds above indicated may be imparted to the two disc
shafts by sets of change spur wheels or by belting but a more convenient arrange-
On
ment is to place on each disc shaft a long lever secured to it by a set screw.
each lever I place a sliding carrier which also by means of a set screw may be
The two carriers are
fixed in any position to vary the length of the levers.
screwed to rods which are each fashioned into a loop at their opposite ends and
swivel on a cross head that slides on a first motion lever pivotted overhead on a
standard at one end and weighted or otherwise set in motion at the other end.
Thus by shifting the crosshead along the first motion lever the carriers will adjust
the relative lengths of the levers secured to the shafts in any desired ratio, which
will be the ratio also of the angular motion of two discs when set in motion by the
weighted first motion lever. By placing a wedge or screw under the weight or its
substitute which actuates the first motion lever the velocity of rotation may be
controlled.
Outside the disc and facing the observer a slotted bar is mounted on each shaft
a microscope being fixed on one end for observing the rim of the disc. The bar is
secured against the disc by a nut running on the screwed end of the shaft so that
by shifting the bar in the slot the microscope can be brought to bear on any point
of the rim of the disc and adjusted to any size of disc.
If now it is observed that the rollers do not tear the bran immediately they
come into simultaneous contact with the grain but slip on the bran surface the
radius of one or both must be increased to render the angle of bite more acute.
If at any point in the subsequent course of the grinding the rollers are observed to
slip because apparently there is no resisting pressure in the grain the difference in
the roller velocities must be decreased. If on the contrary they slip because parts
of the grain burst away under too great pressure the difference in the roller
3 velocities must be increased.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Auguste Arnold Buchholz in the Great Seal Patent Office on
the 1st November 1882.
JOHN AUGUSTE ARNOLD BUCHHOLZ, of Vauxhall in the County of Surrey
Engineer "IMPROVEMENTS IN ROLLER MILLS FOR THE PRODUCTION OF FLOUR
IN APPARATUS TO BE USED FOR DETERMINING THE RELATIVE SPEEDS AND
DIMENSIONS OF THE GRINDING SURFACES."
AND
The quality of flour or its market value is to a considerable extent governed by
the proportion of bran (in a powdered condition) contained therein, and this
reduced bran is the inevitable product of every grinding mechanism known to this
date when employed on bran producing substances.
To diminish the production of such powdered bran I formerly proposed to
concentrate into two grindings all the pressure usually expended in four or five,
required in the reduction of wheat roughly into its constituents of bran and flour
or flour particles in a semi-ground condition.
I have now discovered that a pair of rollers may be so speeded to operate on
grain as to ensure that practically no rubbing shall occur between their grinding
surfaces and the bran surface which rubbing is the origin of bran powder, and
I am thus enabled to secure a result which is tantamount to the simultaneous
decorticating and grinding of the grain.
The rollers I so speed as to cause one roller to roll out the bran of the grain
against the other roller, while the grinding or reduction proceeds at such a modified
rate that the crushing of the flour-producing kernel shall keep pace with the rolling
out of the bran against the slow rotating roller.
In order to attain this result I so proportion the speeds of the two rollers that
the point on the faster roller where the bite of the grain takes place shall reach
the plane of the axes of the rollers by the time that the rolled out bran carried by
the slower roller enters that plane.
I do not limit myself to the diameter of rollers used, or to the use of rollers of
the same or of different diameters, as any variation in their diameters may be
adopted provided the relative surface speeds of the two rollers is so proportioned as
to ensure the above named result.-The grinding may if desired be completed by
one or by several operations according to the setting of the rollers but the speed
of grinding must be reduced in proportion to the completeness of grinding required
to be effected.
This will not however affect the ratio of speed of the two rollers which ratio is
determined by the character of the grain.
It has been generally believed, and the arrangement of mechanism in roller mills
hitherto known supports the belief, that by increasing the diameters of rollers the
amount or extent of rubbing between bran and grinding surfaces is increased
proportionately and that the grinding action obtained from a given proportion of
speed of a pair of rollers is the same for any size of rollers.
Now one of the results of my discovery is that I am enabled to increase the
diameter of rollers without disadvantage.
The ratio of speed for large rollers in accordance with my Invention should be
less than in the case of small rollers.
The operation of bursting open the grain and rolling out the bran on a large

page_text: roller being spread over a larger area is effected with a more favourable angle of
bite and thus the action is much less violent though far more certain.
Moreover small rollers for a given surface velocity bring their working points
more rapidly again and again into action, accumulate heat, and are subject
accordingly to variations of diameter which render the distance adjustment between
the rollers illusory.
One detail of my invention requires special notice.-The ordinary journals of
rollers, indeed of any mechanism, require a certain amount of play because
otherwise they would lock fast with the slightest increase of temperature.-The
consequence is that every form of adjustment provided between the bearings of a
pair of rollers, as hitherto designed, really ranges outside the play within the roller
journals, but that play is much larger (coarser) than the average of adjustment
required, especially for cleaning brans (of flour).
It therefore renders inoperative every mechanism heretofore provided and the
effect of this play has to be neutralized by a number of extra grindings in which
clean brans are brought under the action of the grinding surfaces again and again
merely to present to the grinding surfaces those brans that in consequence of the
uncertain relative adjustment of the rollers escaped previous grindings.
As in my improved roller mill a large amount of pressure has to be exerted
which rapidly destroys ordinary bearings, I propose to mount the roller axles in the
manner shewn in the accompanying drawings, where Fig: 1 is a side elevation
partly in section of the improved roller mill, Fig: 2 a partial front elevation the
side framing shewn being in section; Fig: 3 is a partial front elevation of the
roller mill, and Fig: 4 is a vertical section of the same taken in the line 1, 2.
of Fig: 3.
In these figures A A* are the crushing rollers within the bite of which the corn
to be converted into flour is fed from a hopper B. The plane through the axes of
these rollers is for convenience set at an incline of some thirty degrees with the
vertical.
CC are box frames or standards in which the rollers are mounted.-These
frames are connected together by flanged webs which are cast with the side
frames.
On the axle of the roller A a pair of antifriction wheels a is keyed, and on the
axle of the roller A* a pair of antifriction wheels a¹ is keyed.-These wheels must
be proportioned to the differentiated velocities intended to be given to the two
rollers. Between the wheels a a' roll a pair of antifriction wheels a³ which wheels
have their bearings in swivel frames a-The pivots on which these frames turn
project from the inner face of the standards C in the plane of the axes of the
crushing rollers A A*.-These crushing rollers are carried by bearings which form
part of pairs of supporting arms as a respectively.-These arms are pivotted at their
outer ends to the side standards the upper and lower arm on each side having the
same pin for their fulcrum.
The lower arms a5 are secured firmly to the standards by bolts and nuts the
slackening of which allows of the adjustment of the height of the lower roller by
the insertion of wood blocks or filling pieces between the arms and the cast pro-
jections on the standards to which the arms are bolted.
The arms a. which carry the upper roller A are free to rise and fall with that
roller.
The bearings in which the arms a³ and a terminate are formed to embrace the
antifriction wheels of their respective rollers, and by means of the caps with which
they are fitted they completely enclose these wheels.-Openings however are made
in the peripheries of the bearings to permit of contact being made between the
wheels and adjacent antifriction surfaces; this is best illustrated at Fig: 2.
Situate below the antifriction wheels a¹. are pairs of antifriction wheels a7 which
are carried by arms as. pivotted to the standards C. There is thus provided on.

page_text: each side of the roller mill a group a six antifriction wheels of which the wheels
a³ and a are adjustable as will be presently explained
Surrounding each of these groups of antifriction wheels is an antifriction ring D
(similar to that for which a Patent was granted to Andreas Mechwart bearing
date eleventh February One thousand eight hundred and seventy eight (No 563).
The whole of this arrangement is enclosed in the hollow standards C and shut in
by applying thereto a plate c as shewn at Fig: 1; this permits of the introduction
of lubricating material into the closed case or box thus formed, which lubricating
material will be distributed over the peripheries of the antifriction wheels by means
of the ring D which will always be partially immersed therein.
For adjusting the wheels a³ of the swinging frames I cast the frames with
a slotted end, the slot being at right angles to the plane of the axes of the wheels.
The slots of these frames I fit with sliding blocks e which are bored to receive
the crank pins of a transverse shaft E which has its bearings in the standards C.
Keyed to the shaft E is a hand lever e¹ which carries a screw bolt that enters
a segment slot in a sector e² and carries a clamping nut es on its inner end.-On
moving this handle over the sector an axial motion will be imparted to the shaft E
which through its crank pins will rock the swivel frames and adjust the antifriction
rollers a³ to their desired position.
By this means the distance between the crushing rollers may be increased
or diminished as desired, their adjustment when effected being maintained by
the tightening of the clamping nut e3 which is formed with a handle to facilitate
its use.
It is to provide for this adjustment of the crushing rollers that the antifriction
wheels a are made adjustable to and from each other.-The arms as which carry
these wheels are forked to embrace the wheels and allow of the ring D passing
beneath the wheels and bearing them upwards in contact with the antifriction
wheels a¹.
The forked arms as are pivotted to lugs made fast to the standards C and they
are each provided with link rods a which terminate in metal straps and serve to
embrace excentrics keyed to a transverse shaft F.
Fitted adjustably to one end of this shaft is a band lever f. which moves over a
sector and is capable of being made fast thereto by a bolt and clamping nut f
By giving an axial motion through this hand lever to the excentric shaft F in
one or other direction the antifriction wheels a will be caused to advance towards
or recede from each other as the case may be.
When the crushing rollers are required to be thrust further apart as above
explained by means of the antifriction wheels a³ it will be necessary first to
slacken the pressure of the antifriction rings D on the antifriction wheels a
of the upper roller A.-This is effected by causing the antifriction wheels a' to
recede slightly from each other and thus enable the rings D to rise a proportionate
distance.
When the adjustment of the upper roller A is effected the proper pressure of the
wheels a' on the rings is applied by means of the hand lever f which pressure is
maintained by clamping the hand lever to its sector as above mentioned.
From the foregoing it will be understood how I provide against the rapid
deterioration of the bearings in my improved roller mill and how at the same
time I determine with the greatest accuracy the distance at which the crushing
rollers shall stand with respect to each other, as the nature of the work in hand
may dictate.
I will now proceed to explain how I ensure the simultaneous decortication of
the grain and the reduction of the same to flour in a roller mill, preferring for that
purpose the use of the mill above described.
:
Fig 5 is a diagram which represents a pair of crushing rollers acting upon a
grain of corn; A B being the rollers and ab their axes, and C the grain to be
acted upon. The problem is so to proportion the speeds of rotation of the rollers

page_text: A B as to ensure the rolling out of the skin or bran of the grain on the surface
of the slower roller, say B, while at the same time the flour forming particles are
stripped therefrom leaving the bran spread out. Let it be imagined that the
gran C, as fed to the rollers first touches them at d and e.-Now if the rollers are
properly speeded the grain will be rolled out against the slow roller B, and at a
given instant occupy the position fu.
d
e u
or
d. S
e,f,fu
=
= f u being
It is now clear that while the point d travelled to f (the plane of the axes of the
rollers) the corresponding point e on the slow roller B moves only to the point u
thus determining the relative speed to be in the relation
the spread out bran.
This quantity fu does not necessarily correspond with the circumference of
the grain for it depends on the point of rupture which may also occur near d
or near 8. It is to determine this point with practical accuracy as well as to
decide upon the relative size of the rollers and the relative surface speed to be
imparted thereto, that I have designed the testing apparatus which I will now
proceed to describe.
Fig 6 is a side elevation and Fig: 7 a plan view of the testing apparatus which
consists mainly of two thin rotary discs A. B simulating a pair of grinding rollers
the action of which it is intended to test.-These discs I arrange to test on dead
pressure and also on graduated elastic pressure and I provide for varying the speed
of rotation of the two discs and for observing the action of the discs on the grain
while grinding.
The width of the discs will equal the thickness of any one grain of the species
to be ground, their diameters being proportioned to obtain a proper nip of the
grain at a given distance from the plane of their axes, as indicated in the diagram,
Fig: 5. The disc B which represents the slowly rotating crushing roller is mounted
on a shaft b fitted in fixed bearings, and the disc A which represents the adjustable
and quickly rotating crushing roller is keyed on a shaft a mounted in bearings
carried by a pair of bars G G which are capable of sliding in guides, G¹ G', bolted
to the main frame H.-These bars are coupled together by a cross-piece G³, which
carries at the middle of its length a screw G³.
The frame H carries a cross-piece H' in which is mounted a nut H2 to receive
the screw G. This nut forms the boss of a hand wheel, by turning which the
bars G are caused to slide in their guides, and thereby adjust the position of
the disc A relatively to the disc B.
Keyed to the axles a and b are the arms a¹ 61 which are fitted with sliding
sleeves a²bcarrying a lug for coupling with a pair of pendent rods i i. These
rods connect with a sliding block carried by a sleeve k which has its fulcrum
at and is connected at its free end by a pair of pendent screwed rods . These
O rods at their screwed ends each carry a worm wheel the bosses of which are
threaded to receive the rods.
These worm wheels are mounted in brackets H³ so as to be able to turn freely
therein, and they are actuated by means of worms 12 keyed to a shaft 18-Fitted
to this worm shaft is a chain wheel round which a chain passes to a tension
5 chain wheel at the other end of the frame.
This chain is provided for the purpose of driving the worm shaft, it being
more convenient for the hand of the experimenter than a winch handle on the
worm shaft.
It will now be understood that by turning the worm shaft, an axial motion
O will be imparted to the discs A B the worn wheel 'serving to draw down the
rods and cause the lever with which they are connected to press down the arms
a¹ b¹ on the disc axles and thereby move those arms slowly through a limited arc
such are corresponding with the movement requisite to crush a grain and roll out
its skin as indicated in the diagram fig: 5.
$5
The sleeve couplings ab which connect the arms a¹ b' with the lever kare

page_text: made adjustable so as to vary the ratio of speed of the two discs: thus when they
are caused to approach the axle a the ratio of speed of the disc A will be increased
and when they are moved together nearer to the axle b the ratio of speed of the
disc B will be increased, a corresponding decrease in the speed of the disc A being
at the same time effected.
Fitted to the shaft a at the opposite side of the disc to that on which the arm a¹
is keyed, is a slotted arin m which carries a microscope m¹ through which the
action of the testating apparatus is watched, the axis of the microscope being set so
as to command a view of the grain when first placed in the apparatus.
By thus mounting the microscope it will be caused to follow the action of
the disc A throughout the whole of the arc in which the sample grain is acted
upon, and by this means disclose to the observer the facts on which he is to
determine the relative diameters of the crushing rollers and their relative speed of
rotation.
The apparatus as described displays the results attained under a dead pressure,
but in order that the action of the discs may be observed under an elastic pressure
the inner flange of the hand wheel nut EL is removed or slackened to enable the
nut to move end wise or in the line of the screw stem.
To the cross head G2 a pair of chains G³ is connected which pass over guide
pulleys G mounted in the framing and are weighted at their pendent ends by
moveable weights placed on a cross bar G-The tendency of the load on this
bar is to draw back the disc A from the disc B and it thus acts in opposition
to a yielding or elastic pressure put upon the disc A by an endless band N, which
passes round band pulleys on the axles a b and is held at tension by the
antifriction bowle N' of a weighted rock lever N³ having its fulcrum on the
framing H.-The screw and nut in this case serve to fix the distance beyond
which under graduated elastic pressure of the band N the two discs cannot be
drawn together.
The weight N3 on this rock lever is adjustable to allow of the pressure on the
disc A to be varied at will.
If now the tension pulley lever be weighted so as to produce more pressure than
is required for grinding, and if such a number of weights be placed on the cross
piece chains as will balance the pressure exerted by the weighted tension pulley
the amount of weight which has to be removed from the cross-piece chains to
produce effective grinding will indicate the pressure then exerted on the grain
with sufficient accuracy for practical purposes after deducting loss through friction
which is ascertainable by well-known calculus, and this gauge of the pressure
will form the basis from which to calculate the pressure to be put on the upper
roller of the mill.
Supposing now it is desired to construct a roller mill suitable for working up
an average sample of wheat according to my improved mode of working; I take
at random a number of grains and measure them so as to arrive at their mean or
average thickness.
Of grains answering to this mean size I take any approved number and open
and scoop them out carefully so as to obtain therefrom as perfect skins (brans) as
possible. These skins I then measure and thus obtain an average of their length.
The thickness of grain will be found to bear a certain proportion to the spread out
skin (bran) say 1 to 5, and it is to determine with what means I can lay out this
length of bran upon the slower roller removing therefrom at the same time the
flour producing portion of the grain, that I employ the testing apparatus first
described
The rupture of the skin on pressure being applied to the grain will occur
between and e (diagram 5) near one or other of these points or near the
intermediate point 8.
It is important to ascertain the mean point of rupture, as upon its position will 5
depend the ratio of speed the rollers are to receive. Again the mean point of

page_text: rupture will be governed by the diameters of the rollers, as it is important that
the grain shall not slip when it has once been caught in the bite of the rollers as
at d e. It is mainly to assist in determining these points that the apparatus
above described has been designed and will be resorted to by the roller mill
Manufacturer.
If it is observed through the microscope that the discs representing the crushing
rollers do not tear the bran immediately they come into simultaneous contact with
the grain but slip on the bran surface, the radius of one or both must be increased
by replacing them with discs of larger diameter to render the angle of bite more
acute. If again at any point in the subsequent course of the reduction of the
grain the discs are observed to slip because apparently there is no resisting pressure
in the grain, the difference in the disc velocities must be decreased by readjusting
the connection of the radius arms A¹ B' with the lever k. If on the contrary the
discs are observed to slip because parts of the grain burst away under too great
pressure, the difference in the disc velocities must be increased by readjusting the
connections between the radius arms A¹ B¹, and the lever k through which axial
motion is imparted to the discs
When, by the adjustment of the testing apparatus the desired result is obtained,
and the bran is laid out upon the slowly rotating disc as explained with reference
to the diagram Fig 5, the roller mill manufacturer will have presented to him in
the apparatus the most desirable diameters for his rollers and a clear indication of
the relative surface speeds which he is to give to his rollers in order to ensure by
one operation the rolling out of the bran and the stripping therefrom of the flour-
forming particles of the grain.
By a series of tests I have found that for the purpose of reducing grains of an
average size to flour without tearing the bran, the crushing rollers should have a
diameter of some 24 inches, the mean thickness of the grain being 1/8th of an
inch. This diameter of rollers ensures a bite of the grain at such a point of their
surfaces as will allow of the bran of the grain being laid out flat on the slower
roller by the time that the point on the fast roller indicating the bite, has in the
rotation of the roller reached the plane of the axes of the rollers, and that the
relative speed of the rollers should be as 17 to 30.-This speed is indicated in
Figures 1 and 2 of the drawings.
As the ordinary roller surfaces are usually too smooth to produce the necessary
grip on the grain it will be generally necessary to flute them. The best form of
flute is that which leaves a flat surface on the top of each ridge, and has a shallow
groove with gently inclined sides, as the bran cannot then sink far over the ridges
without finding support at the bottom of the groove.-The diagram fig. 8 gives a
magnified section of a portion of a roller thus grooved. By the use of suitably
sized rollers grooved after this manner the integrity of the bran and germ will not
be endangered, while the maximum of grip with a minimum of normal pressure
will be secured.
Having now set forth the nature of my said Invention and explained the
manner of carrying the same into effect, I wish it to be understood that I claim :
First The arrangement of antifriction wheels above described whereby the
requisite adjustable pressure may be imparted to the rollers through anti-friction
pressure rings without such pressure affecting the bearings of the roller axles.
Secondly: The use of the antifriction wheels interposed between the bearings of
the rollers for separating the rollers and maintaining them at any determinate
distance apart.
Thirdly Speeding the crushing rollers of roller mills, and so proportioning
their diameters to their work, as to ensure the laying out of the skin or bran and
the separation of the flour-forming particles therefrom in the manner and for the
purpose above described.
Fourthly The testing apparatus for providing roller mill Manufacturers with

page_text: the means for determining the diameters and relative speeds of crushing rollers
suitable for ensuring the separation, at one operation, of the flour-forming particles
and the skin or bran of the grain in the manner above set forth.
In witness whereof I the said John Auguste Arnold Buchholz have hereunto
set my hand and seal the Thirtyfirst day of October in the year of our
Lord One thousand eight hundred and eighty two.
J. A. ARNOLD BUCHHOLZ. (L.S.)