Improvements in Ball Grinding MI118.
Year: 1895

page_text: Improvements in Ball Grinding MI118.
I, ALBERT HERZFELD, of Halle on the Saale, Germany, Solicitor, do hereby
declare the nature of this invention to be as follows:-
This invention relates to an improved construction of ball grinding mills wherein
the grinding vessels have not only a rotary motion round their own axes but also
simultaneously a motion round an axis eccentric to those of the vessels so that the
absolute motion is planetary.
I will describe the said invention with reference to the accompanying drawings
in which
Fig. 1 shews a vertical section of a mill constructed according to my invention
and
Fig. 2 shews a plan of one of the grinding vessels with the cover removed.
In a frame B of any convenient form, rotatable round a central axis A, are
mounted rotatable axes a¹ a² . . . to the upper ends of which are fixed the grinding
vessels C. On the central axis A is mounted loose a spur wheel F which gears
with spur wheels Z1 Z2... fixed on the lower ends of the axes a¹ a²
the rotation of the main axis A consequently, not only are the frame B and
vessels C carried round, but also the vessels C C are rotated round their own
axes a! a
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In the grinding vessel are, as usual, balls c which effect the grinding of the
materials in the vessels, the supply of which is effected in the known manner by
means of shoots D branching from a hopper and leading to each vessel and
revolving with the axis A. If a sifting action of the ground material is to be
produced, it is of advantage to separate the sifting chamber from the grinding
space and to arrange it above the latter as shewn on the drawing.
•
The ground material is then made to pass through a narrow slot s through which
the balls cannot pass, to the upper sifting surface of the sifting chamber R into
which the ground particles fall and are there collected. The coarser particles are
made to travel along a curved channel L Fig. 2 back into the grinding space.
The ascent of the ground material along the sides of the vessel is facilitated by the
conical form of the latter.
In the above described construction of ball mill there are always two centrifugal
forces acting upon the balls; firstly that produced by the rotation round the main
axis A, and secondly that produced by rotation of the grinding vessels round their
own axes. The balls are thus caused always to remain at the side of the vessel
which for the time being is farthest away from the main axis A, where they are
consequently made to revolve by the rotation of the vessels on their own axes, and.
by, this means a very energetic grinding action is produced.
The ratio of transmission of the gearing F and Z Z.. is preferably so
arranged with reference to the number of grinding vessels, that the centrifugal
force produced by the rotation round the main axis A is greater than that
produced by the centrifugal force resulting from the rotation of the vessels lourd
their own axes.
".
It is immaterial whether the axes a¹ a ...are arranged parallel to the main
axis A or inclined thereto; also whether their rotation is in the same direction as,..

page_text: or in the contrary direction to that of the axis A. In all cases the grinding action
of the improved mill is superior to that of all known constructions..
Dated this 4th day of February 1894.
ABEL & IMRAY,
Agents for Applicant.
Danl Grinding Mills.
I, ALBERT HERZFELD, of Halle on the Saale, Germany, Solicitor, 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 an improved construction of ball grinding mills wherein
the grinding vessels have not only a rotary motion round their own axes but also
simultaneously a motion round an axis eccentric to those of the vessels, so that
their absolute motion is planetary.
I will describe the said invention with reference to the drawings accompanying
my Provisional Specification in which
Fig. 1 shews a vertical section of a mill constructed according to my invention
and
Fig. 2 shews a plan of one of the grinding vessels with the cover removed.
•
In a frame B of any convenient form, rotatable round a central axis A, are
mounted rotatable axes a¹ a². to the upper ends of which are fixed the grinding
vessels C. On the central axis A is mounted loose a spur wheel F which gears
with spur wheels Z¹ Z³ . fixed on the lower ends of the axes a¹ a².
the rotation of the main axis A consequently, not only are the frame B and
vessels C carried round, but also the vessels C C are rotated round their own
axes a¹ a².
On
In the grinding vessel are, as usual, balls c which effect the grinding of the
materials in the vessels, the supply of which is effected in the known manner by
means of shoots D branching from a hopper and leading to each vessel and revolving
with the axis A. If a sifting action of the ground material is to be produced, it is
of advantage to separate the sifting chamber from the grinding space and to arrange
it above the latter as shewn on the drawing.
The ground material is then made to pass through a narrow slot s through which
the balls cannot pass, to the upper sifting surface of the sifting chamber R into
which the ground particles fall and are there collected. The coarser particles are
made to travel along a curved channel L Fig. 2 back into the grinding space. The
ascent of the ground material along the sides of the vessel is facilitated by the
conical form of the latter.
In the above described construction of ball mill there are always two centrifugal
forces acting upon the balls; firstly that produced by the rotation round the main
axis A, and secondly that produced by rotation of the grinding vessels round their
own axes. The balls are thus caused always to remain at the side of the vessel
which for the time being is farthest away from the main axis A, where they are
consequently made to revolve by the rotation of the vessels on their own axes, and
by this means a very energetic grinding action is produced.
The ratio of transmission of the gearing F and Z Z2 is preferably so arranged
with reference to the number of grinding vessels, that the centrifugal force
produced by the rotation round the main axis A is greater than that produced by
the centrifugal force resulting from the rotation of the vessels round their own
axes.
..

page_text: It is immaterial whether the axes a¹ a² are arranged parallel to the main axis A
or inclined thereto; also whether their rotation is in the same direction as, or in
the contrary direction to that of the axis A. In all cases the grinding action of
the improved mill is superior to that of all known constructions.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
Ball grinding mills with grinding vessels having a planetary motion, substantially
os homin desamited