An Improved Ball Grinding Apparatus.
Year: 1897

page_text: Date of Application, 31st Mar., 1897-Accepted, 22nd May, 1897
CUBE DELE DIECIFICATION.
An Improved Ball Grinding Apparatus.
I, AUGUST BERNHARDT DRAUTZ of 62, Friedrichsstrasse, Stuttgart, in the
Empire of Germany, Civil Engineer, 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 :-
All balls hitherto produced by grinding have the drawback that they do not
receive a mathematically exact spherical form but are mostly of an oval form
which however cannot usually be ascertained with the naked eye nor with the
ordinary measuring instruments. If however finer sighting and measuring instru-
ments be made use of the proof is not difficult to show that the balls are not round.
The cause of the balls not being round is to be attributed to the fact that the balls
when being ground lying in semi-circular grooves between grinding discs rotating
in opposite directions, only receive a tangentially rotary motion. If therefore the
grooves are not exactly semi-circular, a round ball will not be produced. As soon
however as these grooves, even if at first perfectly semi-circular become somewhat
worn an exact spherical form cannot be produced.
The improved grinding apparatus which forms the object of my invention
removes this drawback, by the balls which have been preliminarily turned and then
ground on grinding discs with hollow grooves, being treated between flat grind-
stones which have a rotary movement in opposite directions and also simultaneously
a radial movement of displacement relative to one another. The balls hereby
receive simultaneously with the tangential rotary motion, a radial rotary motion,
which latter is preferably so calculated that it amounts to about one fourth of the
circumference of the ball. A rotary body treated in this manner receives a
perfectly mathematically spherical form, as the ball describes an elliptical_course
and is constantly operated on in two vertical directions by the grinding discs at
diametral points under constant rotation.
In the accompanying drawings,
Figures 1-4 show such a grinding apparatus in which the grinding discs rotating
in opposite directions are also moved radially relative to one another.
Grinding rings z are fastened on separate discs A B which are rotated in opposite
directions by means of shafts D and E and bevel gearing J and J¹ from a bevel
pinion driven by a split belt pulley kk. The discs A and B are not however
rigidly mounted on the shafts D and E but adjust themselves radially on the same
during their revolutions. This radial adjustment is effected by means of an
eccentric d on the shaft D and an eccentric c on the frame C, which are engaged
by rings b and a arranged on the discs B and A respectively. The discs A and B
receive their rotary motion from arms d' fixed on the shaft D and teeth h of a
disc H fixed on the shaft E, the arms d¹ engaging pins a' on the disc A and the
teeth engaging teeth 6' on the disc B.
It is even sufficient if an eccentric or rather radially shifting motion be given to
one disc and grinding ring.
Instead of an eccentric movement one or other or both of the grinding roller
discs may have a radially reciprocating motion imparted to it, whereby a radial
rotary motion is imparted to the balls to be treated in addition to the
tangential one.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
A grinding apparatus for making perfectly spherical balls, characterised by the
rotary grinding discs between which the balls lie during the rotary movement
being also radially displaced relative to one another, in such a way that a radial
reciprocating rotary motion is imparted to the balls in addition to their tangential
rotary motion, substantially as hereinbefore set forth.
تيمم
ديد
1
10057
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.