IMPROVEMENTS IN MILLS OR APPARATUS FOR GRINDING OR REDUCING GRAIN OR OTHER LIKE SUBSTANCES
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by John Henry Johnson at the Office
of the Commissioners of Patents on the 4th May 1881. A communication
from abroad by Wilhelm Seck, of Bockenheim, Frankfort on the Maine, in the
Empire of Germany.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN MILLS OR APPARATUS FOR GRINDING OR
REDUCING GRAIN OR OTHER LIKE SUBSTANCES." A communication from abroad
by Wilhelm Seck, of Bokenheim, Frankfort on the Maine, in the Empire of
Germany.
This Invention relates to improvements in that class of mills in which the
reduction of the grain or other substance under treatment is effected by means of
three crushing or grinding rollers or cylinders arranged one above the other, and
in which two distinct crushing or grinding operations are performed simultaneously,
namely, one between the upper and middle cylinders, and one between the middle
and lower cylinders.
The said improvements consist partly in the manner in which the bearings of
the cylinders are arranged in the hollow cast iron side frames, and in the employ-
ment of certain devices for producing and accurately adjusting the pressure which
the cylinders exert upon each other.
Another part of the improvements consists in a peculiar arrangement of friction
wheels and rollers employed in combination with levers and helical springs to
exert the required pressure upon the cylinders. This arrangement enables the
shaft of the upper friction wheel to be utilised as a feed roller, and also provides
for the simultaneous stopping of the feed immediately when the motion of the
mill is arrested, all of which operations are effected by one and the same lever
handle.
A third improvement consists in the employment of a peculiarly constructed
scraper. This scraper in lieu of consisting of a single blade of steel is formed by a
number of thin steel springs held together between two bars.
These steel springs are arranged close together side by side between the two
bars so as to form a straight unbroken edge. As each spring is enabled to yield
to pressure independently of its neighbours, this scraper adjusts itself to the
cylinder more readily and acts more efficiently than the scrapers constructed in the
usual manner with a single blade, and is moreover not so liable to become heated.

page_text: The Invention further relates to an improvement in the mode of conducting the
grain or grits from the feed hopper to the cylinders in two separate streams, in
such a manner that whilst one grinding operation is being performed between the
upper and middle cylinders a similar operation is carried on between the middle
and lower cylinders.
In carrying out this Invention the three crushing or grinding cylinders are
arranged one above the other; the shaft of the middle cylinder revolves in fixed
bearings attached to the side frames and carries the driving pulley. The upper
and lower cylinders are mounted upon shafts which rotate in moveable bearings,
capable of oscillating to a small extent in a vertical direction upon short arms
jointed to vertical wrought iron tie bars. These shafts are each provided with
two friction rollers, and at each extremity of the tie bars there are pivotted levers
acted upon at one extremity by springs, as hereinafter described, and provided at
the other extremity with suitable bearings for the reception of shafts carrying
friction wheels or rollers of large diameter, which when the mill is at work revolve
in contact with the friction rollers on the cylinder shafts and communicate the
required pressure to the cylinders. The side frames are hollow and the tie bars
are passed through them vertically; these bars are provided at each end with
bolts upon which there are swivelled the levers, one extremity of each of which
carries the bearings for two shafts supporting the friction wheels before referred to.
The frames are arranged at each side of the apparatus. The pair of levers at
the upper extremities of the tie bars and the corresponding pair at the opposite
extremities of the said tie bars carry the two shafts hereinbefore referred to in
suitable bearings. These shafts are each provided with two friction wheels (as
before mentioned), which are arranged between the levers and work in contact
with corresponding rollers on the cylinder shafts.
The upper and lower cylinders are mounted upon shafts working in bearings
supported by the tie bar, to which they are connected by forked arms jointed to
the said bar by suitable bolts or pins in such a manner as to enable these cylinders
to yield to the pressure exerted upon them by the friction wheels, as hereinafter
described. This pressure is produced by means of springs which act against the
extremities of the levers carrying the friction wheels. These springs are connected
to adjustable blocks bearing against a species of knife edge forined upon horizontal
levers, the latter being pivotted at one extremity to the tie bars, and supported at
the opposite extremity by a screwed rod capable of adjustment by means of nuts
bearing against the frame.
It will be observed that the tie bars relieve the cast iron side frames of all the
strain of the cylinders.
The levers carrying the friction wheels at one extremity are connected together
at the opposite extremity by rods provided with nuts for the purpose of adjustment.
These connecting rods are attached to the levers by means of the said nuts at one
extremity, and are joined at the opposite extremity to a species of shackle, which
is formed by straps attached to the upper and lower connecting rods respectively
and passed round excentrics mounted on a shaft; this shaft passes through and is
supported by bearings in both the side frames, and is capable of being rotated by
means of a hand lever at one extremity, and when so rotated the excentrics are
turned with it and cause the connecting rods to move in opposite directions
according to the direction in which the shaft is rotated.
By this means the force of the springs acting upon the levers and pressing the
cylinders together through the intervention of the friction wheels and rollers is
counteracted and regulated at pleasure.
The pressure exerted by each spring is also capable of being adjusted separately
by means of the levers provided with knife edges, and pivotted to the tie bar and
the screwed rods and nuts herein before described. By simply turning the excentrics
the cylinders may be either stopped altogether or the pressure regulated. In one
extreme position of the hand lever the springs are thrown quite out of action; the
friction wheels on the upper pair of levers are moved out of contact with the

page_text: corresponding friction rollers on the shaft of the upper cylinder, and the lower
cylinder is moved out of contact with the middle cylinder. The consequence of
this is that the upper friction wheel stops directly the pressure is taken off the
cylinders. Now the shaft carrying this wheel acts as a feed roller, so that the
feed is also stopped immediately when the pressure is removed from the cylinders,
and the latter are prevented from crushing the produce.
The scrapers employed with this apparatus consist of a number of thin steel
plates made of saw plate or sheet steel. These plates are held between two bars
connected together by screws, and project for a certain distance on one side of the
said bars. The ends of the lower bar are bent at right angles in order to enable
it to be screwed to the side frames. This arrangement enables the scrapers to be
readily and accurately adjusted with reference to the cylinders.
The cylinders are supplied with two distinct streams of produce in the following
manner-
The produce to be ground is contained in a suitable hopper, and is conveyed by
the feed roller to a second hopper divided into a number of compartments by trans-
verse partitions. The first, third, fifth, and other uneven numbered compartments, for
example, discharge their contents at the back, whilst the second, fourth, sixth, and
other even numbered compartments, for example, discharge their contents at the
front. As all the compartments are equally supplied with the grain or grits from
the first hopper, one half of the produce is delivered at the back of the second
hopper on to the upper cylinders, and slides down a board to be crushed between
the upper and middle cylinders, after which the ground produce is finally delivered
on to a shoot, whilst the other half is delivered at the front of the said second
hopper and conducted through tubes or shoots to an inclined plane, down which it
slides to be crushed between the lower and middle cylinders.