IMPROVEMENTS IN GRINDING MILLS
Year: 1884

page_text: I, JASPER WETTER, Engineer, of 67, Strand, in the city of Westminster, do
hereby declare the nature of said Invention for IMPROVEMENTS IN GRINDING
MILLS, a communication to me from abroad by J. C. Wedekind, of Nordhausen,
in the German Empire to be as follows:-
.
This invention has for its object to obtain the advantages of roller mills and
accessories by a peculiar and simple construction of mill stones, adapted to produce
the passage and disintegration of the grain between the stones by ventilation and a
gradual rolling action, instead of the pushing and cutting process of ordinary mill
stones.
For this purpose I divide the grinding surface of each stone into a number of
sectors or panels by means of air channels placed tangentially to a circle equal in
diameter to that of the eye of the mill stone, said air channels or grooves being
narrow and deep near the axis of the stone and made gradually wider and
shallower towards the circumference.
In the case of the upper stone the said channels reach deep into the eye of the
stone (the diameter of the eye being about one quarter of the diameter of the
stone), while in the lower stone they cease at a certain distance from the same, so
as to leave in the centre of the stone a flat ring with a rectangular edge.
The tangential grooves in the upper stone thus form inlets for the grain and air
and allow it to spread uniformly over the grinding surface.
Additional inlets are provided by a number of shafts extending from the upper
surface to the lower surface of the upper stone (through the same) and terminating
in the tangential channels of the same, said shafts being distributed equally around
the centre, and preferably equal in number to the tangential channels.
In some cases the air current may be strengthened by introducing a tube into
the eye of the upper stone, and ventilating hoods (similar to chimney cowls) may
be. placed on the top of the upper stone and communicate through inclined shafts
eitlier with the said additional inlet or feed shafts or directly with the tangential
air channels.

page_text: I, JASPER WETTER, of 67, Strand, in the City of Westminster, Engineer, do
hereby declare the nature of said Invention for "IMPROVEMENTS IN GRINDING
MILLS," a communication to me from abroad by J. C. Wedekind, of Nordhausen,
Germany, and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:—
This invention has for its object to obtain the advantages of roller mills and
accessories by a peculiar and simple construction of mill stones, adapted to produce
the passage of the grain between the stones by ventilation and a gradual rolling
action, instead of the pushing and cutting process of ordinary mill stones.
For this purpose the eye of the improved mill stone has a diameter about one
fourth of that of the millstone, and the surface of the latter is divided into a
number of sectors or panels by means of grooves placed tangentially to the circle
formed by the eye.
The grooves separating the adjacent sectors or panels form air channels; those of
the lower stone cease near the eye, while those of the upper stone reach deep into
the eye and become gradually shallower and wider towards the circumference.
The tangential grooves in the upper stone (which commence in the eye at a
considerable depth) thus form inlets for the air and grain and allow the latter to
spread uniformly over the grinding surface.
The grinding surfaces may be either smooth or riffled (sharpened or dressed).
The grain is introduced not only through the eye of the stone, but also through
special channels or shafts the inlets of which are situated in a circle in which
terminate the tangential air channels serving to feed the grinding surfaces.
If required, the current of air may be strengthened by the insertion of a tube
into the eye of the upper stone, or by means of ventilating hoods (similar to
chimney cowls) placed on the top and which serve to supply air through inclined
shafts either to the special shafts already described or directly to the tangential air
channels.
For regulating the current of air, the tubes are made telescopic.
The upper edge of the eye of the lower stone, instead of being interrupted or
broken, forms a sharp right angle.
Its air channels are also placed tangentially to the circle formed by the eye of
the upper stone. They begin, however, at a circle the diameter of which is a few
centimetres larger, so as to leave in the centre a closed annular surface, which has
for its object to obtain a thorough sweeping action with the edges of the grinding
surfaces of the upper stone, when the latter pass over the lower stone.
The grooves reaching into the eye of the upper stone form projections which suck
in air and grain and gradually supply the same to the grinding surfaces through
the gradually widened and shallowed grooves.
The accompanying drawing represents a set of grinding stones embodying the
invention.
Fig. 1. is a section of the upper stone along the lines a, b, c, d of Fig. 2.
Fig. 2 is a bottom view of the same.
Fig. 3 is a side view of an upper stone provided with ventilating hoods.

page_text: Fig. 5 is a section of the upper stone, when the supply is effected through the top
by special shafts.
Fig. 6 represents the grinding surface of the upper stone, Fig. 5.
Fig. 7 is a side view of the same.
Fig. 8 is a plan.
fare the edges of the grinding surfaces leading tangentially from the eye.
g are the air channels.
h are the grinding surfaces, which may be sharpened or smooth.
k are the feeding holes or special shafts arranged in a circle.
Z are the air tubes.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, as communicated to
me by my foreign correspondent, I declare that what I claim is
1. A millstone divided into sectors or panels by air channels forming tangents to
a circle equal in diameter to that of the eye, the said channels being deep and
narrow near the centre of the stone, and gradually made shallower and wider
towards the circumference; the channels of the upper stone reaching deep into the
eye of the same.
2. A grinding mill adapted to be supplied with raw material from the top
through special shafts situated in a circle and leading to the air channels.
3. Ventilating hoods or cowls mounted on the top of the mill stone, in com-
bination with air shafts leading to the air channels of the grinding surface.