IMPROVEMENTS IN PROCESS AND MACHINERY FOR CLEANING AND SCOURING RICE AND OTHER GRAIN
Year: 1882

page_text: LETTERS PATENT to Melville Church of the City of Washington, District of
Columbia United States of America Patent Solicitor, for an invention of
"IMPROVEMENTS IN PROCESS AND MACHINERY FOR CLEANING AND SCOURING
RICE AND OTHER GRAIN."-A communication by David Lukins Shoemaker
of Georgetown in the District of Columbia and United States of America.
COMPLETE SPECIFICATION filed by the said Melville Church at the Office
of the Commissioners of Patents on the 6th April 1882.
MELVILLE CHURCH of the City of Washington, District of Columbia, United
States of America, Patent Solicitor IMPROVEMENTS IN PROCESS AND MACHINERY
FOR CLEANING AND SCOURING RICE AND OTHER GRAIN; a communication by
David Lukins Shoemaker of Georgetown, in the District of Columbia and United
States of America.
Fig. 1 is a longitudinal vertical section of my improved machine, taken on the
line x, x, fig. 3. Fig. 2 is an end elevation of the same. Fig. 3, is a transverse
section taken on the line y, y, fig. 1. Similar letters of reference in the several
figures denote the same parts.
My invention has for its object the cleaning and scouring of rice in a new and
improved manner and by novel and improved machinery, and it consists, first, in
the hereindescribed process of scouring and cleaning rice. It further consists in
the combination substantially as hereinafter described, of the two screen surfaces,
the brushes, and the means for forcing currents of air through said surfaces and
through the rice contained between them. It further consists in the several specific
devices and combinations severally, hereinafter described and claimed.
In the drawings A, represents the frame of the machine B, the outer screen
and C, the inner cylinder or screen. The outer screen B, is constructed preferably
of wire cloth, and for convenience is divided into two parts of halves as shown in
fig. 3. Various kinds of wire cloth have been employed by me in the construction
of the outer screen but the most satisfactory results have been obtained with cloth
woven of square wires. For ordinary rice in a good average condition I have

page_text: .
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found that about ten or twelve meshes to the linear inch, answers the purpose
satisfactorily; but as the character and condition of the crop is liable to vary by
reason of the different conditions of growing, harvesting and storing it, whereby,
the rice is more or less easily cleaned and also more or less easily broken;
I recommend that the manufacturer provide himself with sets of outer screens
having meshes of different degrees of fineness and adapted to be substituted for
each other, so that if the rice breaks more easily he can use a mesh of greater
fineness or on the other hand, if the grains are tough and the skin adhere strongly,
he can use a coarser mesh. Extending longitudinally through the outer screen is
a fan shaft D, provided with lateral arms d and blades d', and to these blades and
arms the inner cylinder C, is secured. The inner cylinder may consist wholly of
wire cloth or perforated sheet metal, but I preferably construct it of alternate wire
cloth sections c, and imperforate sheet metal sections c¹, as shown in fig. 3, in order
that the current of air induced by the fan, may be forced through the perforated
sections, thence through the rice and out through the outer screen in the form of
sharp blasts.
A series of longitudinal brushes E, are secured to the outside of the inner
cylinder C, preferably one over each blade, and arm of the fan and extend outward in
close proximity to the outer screen as shown in figs. 1 and 3. . Openings are made
in one or both of the end casings of the machine for the admission of air to the
interior of the inner cylinder. In the operation of the machine a rapid rotary
motion is imparted to the fan and to the inner cylinder secured thereto by power
applied to the fan shaft and the 'hulled rice is fed in through a feed spout or
hopper F, at one end of the machine, and passing down in between the inner
cylinder and outer screen partakes of the inotion of the inner cylinder and is
carried round and round by the brushes and kept in contact with the outer screen
by centrifugal force until all the "douce" or skin is scoured off of it and forced
by air blast out through the meshes of the outer screen. Owing to the close
proximity of the inner cylinder and outer screen to each other there is no
opportunity for the rice to be thrashed about and broken up, but it is gradually
scoured and is finally delivered from the discharge spout G, of the machine in a
merchantable condition without further screening. After passing through this
scouring machine the rice is preferably passed through another machine termed a
"polisher" similar to the one herein-described except that in lieu of the outer
screen an outer cylinder of fine wire, leather or raw hide is employed. When raw
hide is used, it is preferably applied with the hair side exposed as the polishing
surface, in order to attain the best results. The polisher imparts to the rice a.
beautiful pearly appearance which greatly enhances its merchantable value.
I have found by practical experience, that the successful operation of the machine
for cleaning the inner skin, or douce from rice in the manner herein described
depends upon two correlated conditions to wit, the surface speed of the parts which
effect the cleaning or removal of the skin, and the time during which the rice is
subjected to the action of the cleaning mechanism which must be so proportioned
or graduated to each other that the rice will be effectually scoured or cleaned
without being broken or injured. If the machine runs to fast, the rice is liable to
be broken, if too slow, it is not perfectly cleaned. If the rice is not retained in
the machine a sufficient length of time it is not perfectly cleaned and if retained
too long it is broken or injured. I have obtained excellent results with the
Scouring surfaces six and one half feet in length, the inner cylinder ten and three
forths inches in diameter, the space between the inner cylinder and outer screen
about one and one half inches, with brushes extending from the cylinder to within
about one eighth of an inch of the outer screen, and with the fan shaft and inner
cylinder revolving at about two hundred and seventy five revolutions per minute,
all said parts being constructed substantially as herein described and as shown in
the drawing; and I would recommend that in varying these proportions care be
taken to secure substantially the same surface speed with the same rate of feed
through the machine, or in other words that if the speed be increased or reduced

page_text: the rate of feed through the machine be proportionately increased or reduced so
that substantially the same amount of scouring action be obtained. As the rice
however, is liable to vary somewhat in condition from various causes as above
indicated, it may sometimes be found necessary to slightly increase or retard the
rate of feed, or the peed, or both. In my experience the operation of the machine
can readily be varied to adapt it to rice of different conditions, by slightly raising
or depressing one end of the machine. Thus if the rate of feed should be increased
it can easily be accomplished by raising the feed end or lowering the discharge end
a few inches so that the gravity of the rice will slightly assist its passage through
the machine; and on the other hand, if the rate of feed should be decreased such
result can be accomplished in a similar manner by lowering the feed end or raising
the discharge end of the machine in order that gravity may retard the passage of
the grain through the machine. I have also in some cases decreased the scouring
'action of the machine, upon the rice, by removing a portion of the wire cloth near
the tail end of the outer screen which may be put on in sections for that purpose
and in other cases have varied the speed of the inner cylinder.
The whole scouring machine may be encased if desired and the douce or thin
skin removed by the scouring operation and forced out through the outer cylinder,
may be drawn off from within said outer case by a suction fan and conveyed to
any suitable place of deposit. In this machine as here constructed it is absolutely
necessary that the two scouring devices, to wit, the inner revolving cylinder and
the outer stationary screen, should be arranged substantially horizontal, as they
can be varied from that position only to a slight extent without entirely destroying
the practical utility of the machine for the purposes of cleaning rice. It will of
course be seen that the wire cloth screen can be made to revolve, but in this case
care should be taken to arrange the surface speed of the parts with relation to each
other, substantially as I have above indicated. The practical results of the machine
being entirely dependent upon the combination of the proper relative surface speed
of the cleaning mechanisms with the proper relative movement of the grain through
the machine between said cleaning surfaces or mechanisms.
The brushes are arranged as above described longitudinally of the cylinder to
which they are attached and not spirally; as I have found that with horizontal
cylinders or scouring surfaces a spiral arrangement of the brushes will either so
accelerate or retard the movement of the grain (accordingly as the spiral may
arranged) as to destroy the efficiency of the machine. Of course if the spiral be
so slight as to produce no practical effect it would be substantially the equivalent
of the longitudinal arrangement and would come within the limits of my invention.
The brushes which I have employed have been made of stiff bristles although any
equivalent substance may be employed. In a machine of the size herein described
I have employed six brushes each having a width of three rows of bristles and a
length equal to the length of the inner cylinder, the spaces or pockets between the
brushes being about seven inches in width. I have attached the bristles in the
ordinary way to wooden strips about five eighth of an inch thick and one inch
wide and fasten said strips to the longitudinal ribs of the inner cylinder. The
front edges of the wooden strips may be covered with sheep skin or other soft
substance to prevent them from breaking the rice. The air blast should not be
generated by a suction fan drawing the air through a wire screen, but should be
a positive blast forcing the air through the part that carries the brushes thence
through the grain and out through the wire screen. When the machine is arranged
as shown in the drawings the blast may be generated as shown, by a fan within
the revolving cylinder or by any equivalent means either within or without the
cylinder which will produce a sufficient air pressure within the inner cylinder to
cause the air to pass through its perforations and out through the grain and the
outer screen in the manner described. Without the air blast the douce or outer
skin of the grain will collect in little masses or balls, attach themselves to the
brushes, gradually obstructing their operation, and will finally break off and come
out of the machine with the scoured rice, thus rendering the product impure and

page_text: necessitating a subsequent cleaning operation of a different character. By reason
of the oily nature of the douce it is very difficult to completely free the rice from
it, except by the action of the positive blast, attacking and removing it entirely
from the rice as fast as it is scoured off from the grain. In the, operation of this
machine not only is the inner skin scoured off and removed from the douce, but the
soft oily germ end of the berry is at the same time detached and removed, whereby
the merchantable article is improved in quality and enabled to keep in good con-
dition for a great length of time. By the processes and machinery heretofore
employed and now in general use for scouring and cleaning rice, the hulled material
has to be pounded in mortars for a time averaging two hours in order to remove
the skin and germ-ends; by the machine herein described, as shown by actual
practical tests in the mill this operation is accomplished, in a better manner, and
resulting in a superior article, in a time averaging about one quarter of a minute,
and with the expenditure of but a small fraction of the power required by the old
process..
Having thus described the invention and the manner in which the same is to be
performed, what I claim as new is:
1st The improved process of cleaning and scouring rice, consisting in subjecting
the hulled rice to the scouring action of a horizontal outer cylindrical screen and
an inner revolving cylinder provided with the longitudinal brushes projecting in
close proximity to the outer screen and under the action of a blast or blasts of air
forced from the inner cylinder through the outer screen, substantially as
described.
2nd. In a machine for cleaning and scouring rice and other grain, the combina-
tion, substantially as described of a horizontal outer cylindrical screen an inner
revolving cylinder armed with longitudinal brushes which project in close
proximity to the outer cylindrical screen, and means for forcing currents or blasts
of air from the inner revolving cylinder out through the outer screen.
3rd. In a machine for cleaning and scouring rice and other grains the combina-
tion, of a horizontal outer cylindrical screen, an inner revolving cylinder between
which and the outer screen the rice is fed, longitudinal brushes on the inner
cylinder projecting in close proximity to the outer screen and operating to press
the rice against said outer screen to scour it, and a fan arranged within the inner
cylinder for forcing a blast or blasts of air outward through the rice and through
the outer screen to remove the scoured off particles substantially as described.
4th. In a machine for cleaning and scouring rice, the combination of a horizontal
outer cylindrical screen, an inner cylinder provided with longitudinal brushes
projecting in close proximity to the outer screen, and an air forcing fan for sup-
porting and rotating the inner cylinder and forcing air currents or blasts out
through it laterally and through the outer screen; substantially as described.
5th In a machine for cleaning and scouring rice, the combination of an outer
cylindrical screen, an inner cylinder consisting of alternate perforated and imper-
forated sections, and open at one or both ends, brushes on the outside of the inner
cylinder and a fan within said cylinder, whereby the air is directed from the fan
through the perforated section of the inner cylinder in the. form of sharp blasts,
substantially as described.
"
In witness whereof I the said Melville Church have hereunto set my hand
and seal this 6th day of April in the year of our Lord One thousand
eight hundred and eighty two.
MELVILLE CHURCH. (L.S.)