Improvement in Chucks.
Year: 1896

page_text: Date of Application, 4th Feb., 1896-Accepted, 9th May, 1896
Improvement in Chucks.
1, ERNST SCHMIDTMANN, Work-master of Wismar in the Granduchy of
Mecklenburg-Schwerin, Germany 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:-
The present improvement relates to a chuck for the reception of bearings,
sockets etc., which are to be bored, of such a kind, that it always holds centrally
the work-pieces that are put into it, so that it is no longer necessary as hitherto for
the workman to be continually adjusting them and thereby losing much time.
In the annexed drawing such a chuck is represented in longitudinal section a
Sellers-bearing being fixed in it for boring.
A is a cylindrical hollow body, bored exactly cylindrically in the inside, having
at its further end a piece B provided with an inside screw-thread, by means of
which it is screwed on the mandril C of the mandril stock. The transition from
the cylinder A to the piece B is formed by a cone D. Into this cylinder A first of
all a hollow cone D, whose side-inclination corresponds exactly to the inclination
of the conical part of the chuck is pushed in to the bottom of the chuck.
The picce E is used to close the cylindrical chuck. It has the same diameter as
the chuck A and has a cylindrical shape on the outside. In the inside, on the
contrary, this cylinder is turned corresponding to the cone of the piece D and
provided on the outside with a central opening F, which serves for the introduction
of the drill.
The piece E is furthermore provided with a key G, by means of which it can be
slid sideways in a groove of the chuck, without a rotation of E taking place. In
order further completely to close the chuck, a cover H is put on this piece E by
screwing it on the thread of the chuck, which has a bore J corresponding to the
bore F of E.
As will be seen from the drawing, the back piece E is provided with a ring K,
which fits into a corresponding groove of the cover H. This arrangement has no
special purpose and may be omitted; when the chuck is to be used, it is screwed on
the mandril C after the piece D has been pushed in, the bearing L (socket etc.)
pushed in and the closing-piece E put on.
At the same time the work-piece, that is to be bored is accurately centred; by
screwing on the cover H, when in consequence of the groove and key the closing-
piece E cannot turn, the workpiece is then put in firmly between D and E.
By means of this chuck work-pieces of the most various length and thickness can
be bored.
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 1
claim is:
Self-centring contrivance for fastening hollow bodies that are to be bored,
distinguished by the arrangement of two hollow cones (D, E) in a cylindrical
socket (A) one of which, being hindered from turning by a key (G) running in a

page_text: groove of the socket, is firmly pressed against the work-piece by means of a
centrally bored cover (H) which can be screwed on to the socket.
Dated this 29th day of January 1896.
For ERNST SCHMIDTMANN,
Bernh. Brockhues.