Improvements in Mixing Machines for Flour and other Pulverulent Material.
Year: 1893

page_text: Date of Application, 19th Apr., 1893-Accepted, 20th May, 1893
Improvements in Mixing Machines for Flour and other Pulverulent
Material.
I, ROBERT HARTMANN of Kerb'sche Muehle near Dingelstaedt (Eichsfeld) in
the German Empire do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :--
This invention relates to a machine for mixing pulverulent substances of all
kinds and will be understood by reference to the accompanying drawing and the
following description,―
The machine is represented in
Figure 1 in vertical section and in Fig. 2 in plan, the cover being removed.
The apparatus is exceedingly simple; it consists of a stationary cylindrical
vessel A with a conical bottom B to the lower part of which is secured the
outlet D. In the centre of the vessel A a cylindrical tube or hollow shaft C is
arranged, which extends the whole length of the apparatus and terminates at its
lower end in the opening in the bottom B. This tube or hollow shaft C is
provided with openings which are formed by cutting open and bending outwards
the shell, and is mounted in a suitable manner on a shaft F by which it is rotated
by means of a pulley F¹. Above the conical bottom B of the vessel A. and parallel
or nearly parallel to this bottom at a certain distance therefrom inclined shelves E
are arranged between which are left openings B' and B2 in the manner shown in
Fig. 2. The vessel A is closed by a cover J which for the purpose of charging
the materials to be mixed is provided with an inlet or may be arranged to open in
a suitable manner.
If the shelves E are dispensed with the machine works as
follows;-
The pulverulent materials which are to be mixed having been charged in any
suitable succession into the vessel A and the hollow shaft C having been rotated,
the parts of C which are cut out and bent outwards operate like cutters and remove
particles of the material and allow them to fall mixed with each other through C
to the outlet D. After a short time however this operation stops, as only the
particles of the material which rest directly against the periphery of C, are seized
while the other part remains in the shape of a tube.
To prevent this and to effect a continuous operation of the machine the shelves E
are provided. These shelves allow the materials to be mixed to pass only through
the two openings B' and B2. If the pulverulent materials were of greater stability
than they are in reality, the space between the two shelves E and the bottom B
would remain empty; notwithstanding this, flour etc. when treated in this apparatus
enters that space, but it cannot become compacted above the bottom B as it is
quickly discharged by means of very large apertures in the tube or the hollow
shaft C.
By the shelves E the whole mass of the material is divided into two columns
one of which (the column which stands on the bottom B) is discharged more
quickly by the lower part of the tube or hollow shaft C than the other, which
stands on the shelves E. In consequence of this the mass that forms the first
column slides down quicker than that forming the second column; a differential
motion arises in the mass of the materials and a necessary consequence of this is
that as particles are discharged by the tube or hollow shaft C, the rest of the
mass slides downwards to the centre of the vessel A. so that constantly new particles
of the material can be seized or removed by the tube or hollow shaft C.
To maintain or to increase this difference in the speed of the two columns

page_text: throughout the whole apparatus several shelves E' E" are inserted at certain
distances apart and parallel to the shelves E. These shelves E' E' must be
arranged exactly vertically above the shelves E and must have similar openings B¹
and B between them.
In order to reduce the dead space in the machine to a minimum the shelves E¹ E"
eto. are provided at their outer parts adjacent to wall A with apertures G. By
these last described means the upper portion of the mass by its pressure on the
lower portions increase the motion towards the centre of the vessel. In consequence
of the different speeds at which the two columns of the material descend con-
siderable friction arises between the surfaces at which they touch each other which
tends to draw the material downwards and in combination with the inclination of
the bottom B, to the tube or hollow shaft C by which means the material is
constantly conducted under pressure to C so that the material energetically enters C.
In consequence of the pressure which the upper layers give to the lower layers the
latter are more strongly pressed against C than the former. If therefore the
apertures in C were everywhere the same the apertures in the lower part of
the tube would discharge greater quantities than the upper apertures, and the flour
or other material under treatment would become unequally mixed. To prevent
this and to compensate for the greater discharge from below the shelves E, narrow
apertures in the tube C are provided just above the shelves E. The size of these
apertures is gradually increased toward the upper part of the apparatus where the
pressure of the mass is lowest. In this manner an always proportionate entering
of the material from all layers is attained.
In most of the modern mixing machines chambers or compartments one beside
another are necessary, which must be filled before the mixing process takes place.
This arrangement requires considerable intermediate mechanism, great attention
and much time.
In the present machine the material may be charged unsorted and when the
machine is in full operation it is simply introduced into the vessel A.
It is quite immaterial in what succession the materials to be mixed are charged
into the machine and the effect of the machine is the same whether equal or
unequal parts of the materials to be mixed are charged after each other or mixed
with each other. The tube or hollow shaft C seizes the surrounding flour every-
where proportionately so that it is mixed intimately and in the desired proportion
while sliding down C.
The machine is of the simplest construction and by its use a considerable saving
of power is obtained, and as an immediate and unprepared filling up, even during the
operation of the machine can take place, the machine works more satisfactorily
than other machines.
It is obvious that the machine may be manufactured in various sizes and for any
quantity of flour or other material to be mixed.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is;-
1. A machine for mixing pulverulent material in which the materials which
have been charged in any suitable order of succession into a cylindrical vessel to
be mixed therein are divided in parallel columns which stand on different bases in
such a manner that they move at different speeds downwards and towards the
centre of the vessel where they are proportionately mixed and discharged.
2. In apparatus such as claimed in Claim 1 a vessel such as A above the conical
bottom B of which the lower part forms the outlet D are provided shelves such
as E with openings B' B2 between them whereby the materials in the vessel A. are
divided into separate columns of different size which are respectively supported on
the bottom B and shelves E in such a manner that on taking away the material
at the lower part of these columns a differential motion arises downwards and towards
the centre of the vessel the material being supplied at constant pressure to a

page_text: rotating tube or hollow shaft such as C which is arranged vertically in the vessel
and through the apertures of which the material passes on its way to the outlet D.
3. In a machine such as claimed in Claim 2 a tube or hollow shaft C the
apertures of which for receiving the materials are formed by cutting open and
bending outwards the shell and which to correspond with the varying degrees of
pressure are gradually decreased in size as they approach the lower part of the
apparatus so that the material can proportionately be mixed and discharged
substantially as described.
Dated this 19th day of April 1893.
W. P. THOMPSON & BOULT,
Agents for the Applicant.