IMPROVEMENTS IN GRINDING MILLS
Year: 1877

page_text: LETTERS PATENT to William Newzam Nicholson and William Mather, both
of Newark-upon-Trent, in the County of Nottingham, Agricultural Engineers,
for the Invention of. "IMPROVEMENTS IN GRINDING MILLS."
Sealed the 27th October 1877, and dated the 10th May 1877.
PROVISIONAL SPECIFICATION left by the said William Newzam Nicholson
and William Mather at the Office of the Commissioners of Patents on the 10th
May 1877.
WILLIAM NEWZAM NICHOLSON and WILLIAM MATHER, both of Newark-upon-
"IMPROVEMENTS
Trent, in the County of Nottingham, Agricultural Engineers.
IN GRINDING MILLS."
This Invention has for its object improvements in grinding mills made of metal,
which improvements are also applicable to grinding mills made wholly or partially
of metal, stone, consolidated emery, or other material.
In various grinding mills already in use it has been customary to employ a drum
approximately of a conical shape, working within a concave or cylinder of a similar
form, such drums and concaves having sharp edged grooves upon them for the
purpose of cutting, kibbling, or grinding the grain or other substance for which such
mills are used.
Our improvements consist in making the drums and concaves of such mills in the
shape of a bell, or with a trumpet mouth, formed in such a way that when the drum
is withdrawn for a short distance from the concave for the purpose of grinding
coarsely or kibbling, the coarsely ground substances pass the trumpet mouth by
which the finer part of the grinding would be performed without being further
operated upon.
These
For grinding finely, the drum is moved further within the concave, when the corn
or other material being first operated on by the straighter part of the drum passes
onward, and the finer grinding is done at the trumpet mouth, which from its
increased diameter runs at a greater velocity than the narrower part.
narrower parts of the drums and concave are cut with grooves in such a way that
the edges of the grooves in the drum meet the edges of the grooves in the concave,
so as to give a cutting or shearing action, whilst at the trumpet mouth the grooves

page_text: in the concave are cut either the same way as those in the drum, or have their
edges thickened, so as to give a rubbing or grinding action, by which finer meal is
produced.
We propose to feed these mills with an arrangement of discs fixed excentrically
on a spindle, which discs revolve within the circular pipe forming the outlet of the
hopper, and are so contrived that the feed ceases immediately the mill stops.
For the purpose of preventing accident to the grinding part of the mill from a
stone, nail, or other hard substance getting into it, we arrange a lever with a weight
or spring which holds the drum in proper position for grinding, but which on the
intrusion of any hard substance allows the drum and concave to move away from
each other, and at the same time disengages the driving pulley, which acts by either
a clutch or friction cone upon the drum shaft, allowing the said driving pulley to
revolve without actuating the mill, or throws the belt off the driving pulley on to a
loose pulley. This arrangement of mill, feed motion, and safety contrivance may be
made either vertical or horizontal, and the grinding parts either of metal, stone,
consolidated emery, or other substance, or partly of one, and partly of another
substance.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Newzam Nicholson and William Mather in the Great Seal
Patent Office on the 10th November 1877.
WILLIAM NEWZAM NICHOLSON and WILLIAM MATHER, both of Newark-upon-
Trent, in the County of Nottingham, Agricultural Engineers.
"IMPROVEMENTS
IN GRINDING MILLS."
This Invention has for its object improvements in grinding mills made of metal,
but which Invention is also applicable to grinding mills made wholly or partially of
metal, stone, consolidated emery, or other material.
In various grinding mills it has been customary to use a drum of a conical shape,
working within a concave or barrel of a similar forin, such drums and concaves
having sharp edged grooves upon them for the purpose of cutting or grinding the
grain or other substance for which the mills are used.
Our improvements consist in making the drum and concave of such mills in the
shape of a bell, or with a bell or trumpet mouth, formed in such a way that when
the drum is withdrawn from the concave for a short distance for the purpose of
grinding coarsely, or for what is called kibbling, the coarsely ground grain or other
substance passes the trumpet mouth by which the finer part of the grinding is
performed without being further operated upon.
When the drum is brought closer to the concave for grinding finely, the corn or
other substance is first operated on by the straighter part of the drum, and passing
onward the finer grinding is performed at the trumpet mouth, which. from its
increased diameter runs at a greater velocity than the narrow part. The straighter
part of the drum and concave is cut with the edges of the grooves in the drum,
meeting the edges of the grooves in the concave so as to give a shearing or cutting
action, whilst at the trumpet mouth the grooves are cut so as to give a rubbing or
grinding action, by which fine meal fit for dressing is produced.
Our improved method of feeding these mills consist of an arrangement of discs on
a spindle revolving within a circular hopper spout, which discs are so contrived that
the feed ceases the moment the mill is stopped.
In the accompanying Drawings,―
Figure 1 shows a longitudinal section through our improved vertical mill. A is
the mill frame, or stand; B, the bell-shaped grinding cone connected with a vertical
spindle S, which is capable of being raised or lowered to the concave by any of the
ordinary methods. C is the grinding concave, which is fixed upon the frame of the
mill. The grinding cone is shown in the proper position for fine grinding. The

page_text: dotted lines a, a, show the cone lowered into the position for coarse grinding. With
the drum thus lowered there is space at Z for the coarsely ground substance to pass
without being further operated on.
Figure 2 is a side elevation of the grinding cone; Figure 3, a section of the same
through the line X, Y, showing the method of grooving; Figure 4, a vertical section
through the concave; Figure 5, a part plan of the same.
It will be seen that the grooves in the upper part of the cone, shown in section
on Figure 3, are so formed that in work their acute edges meet the acute edges of
the grooves in the concave, Figure 4, so as to give a cutting or shearing action. The
form of the grooves at the bell mouth of the grinding cone is shown at b, b. They
are made the reverse way from those in the upper part of the cone, so that in work
they have a rubbing rather than a cutting action.
Figure 6 shows a longitudinal section of our improved feed arrangements, and
Figure 7, an end elevation of the feed discs removed from the circular hopper spout
in which they revolve. D is the hopper spout, and E the feed discs, one of which is
diagonal, and the other on the plane of the axis of the revolving spindle. This
spindle may be driven from a belt working on a speed cone F, as shown, or in any
other suitable manner. Each revolution of this disc contrivance brings the grain or
other substance forward to the grinding part of the mill, but when stopped, effectually
cuts off the feed.
The arrangement of mill and feed motion herein described may be applied to
either vertical or horizontal mills, and the grinding cone and concave made either
of metal or other substance, or partly of one substance and partly of another.
In witness whereof, we, the said William Newzam Nicholson and William
Mather, have hereunto set our hands and seals, this Ninth day of November,
One thousand eight hundred and seventy-seven.