Improvements in Turret Heads for Milling Machines and like Tools.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improvements in Turret Heads for Milling Machines and like Tools.
ABRAHAM HOPWoon, 3, Culwell Terrace, Cannock Road, Wolverhampton, in
the County of Staffordshire, Engineer, do hereby declare the nature of this
invention to be as follows:
This invention relates to improvements in that type of apparatus commonly
known as dividing heads, or. turret holders, which are used for holding certain
articles such as cocks, valves, screws, or the like, while the said articles are
being acted upon by milling machines or other cutters.
The object of this invention is to construct a dividing head in such a manner
that
(1st.) The articles to be machined may be easily and quickly put into, and
taken out of the said apparatus ;
(2nd.) To construct it in such a way that any wear, and tear which may take
place will not affect the accuracy of the apparatus, and,
(3rd.) To lock the revolving portion of the apparatus quickly, and rigidly in
the different positions without the aid of a spring or springs. I will now proceed
to describe my said invention together with the methods employed therein, to
bring about the above results. The lower portion which is bolted or otherwise
fastened to the machine table is bored out taper to receive the revolving portion,
which fits accurately therein. To the side of the lower or fixed portion, is
attached a nut, or sleeve, having an internal screw of coarse pitch cut therein,
and a suitable bolt having an external screw which fits the nut or sleeve is pro-
vided. A little more than half the thread of both the nut and bolt is cut away,
so that when put in a certain position one will slide inside the other, but when
the bolt is partly rotated, the threads engage with each other as in an ordinary
screw. This device is commonly known as a breech screw. The point of the
bolt is made taper, and suitable holes are provided in the revolving portion of
the apparatus, into which the point of the bolt enters. It is then partly rotated,
when the threads engage, and the bolt is forced into the hole, thus locking the
one portion of the apparatus firmly to the other. The revolving portion of the
apparatus has a cap or cover wherein is a circumferential groove, which is true
with the conical part which fits into the lower or fixed portion.
Into this groove is fitted a ring, portions of which are cut away in such a
manner as to form two eccentric cams. A groove is also provided across the
revolving portion, in which two blocks slide. These blocks engage with the
eccentric cams in such a way that when the above mentioned ring is partly
rotated, the blocks slide to & from each other; and suitable dies attached to the
locks grip the article to be machined. A suitable handle or handles are attached

page_text: to the ring for rotating the same, or a worm, and worm wheel may be employed,
or again a tooth wheel, and pinion may be used for rotating the ring. The
above mentioned cap or cover keeps the parts in position, and also prevents
dirt or swaif from getting into the apparatus.
Dated this 22nd day of February 1899
Improvements in Turret Heads for Milling Machines and like Tools.
I, ABRAHAM HOPWOOD, of 3, Culwell Terrace, Cannock Road, Wolverhampton, in
the County of Stafford, Engineer, do hereby declare the nature of this 1
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 improvements in that kind of apparatus commonly
known as turret heads, dividing chucks or capstan holders, which_are_used_on_
milling machines and like tools for holding or chucking parts of machinery
such as cocks, valves, screws or the_like_while_they_are_tooled_by_milling cutters.
or other tools.
1
The object of this invention is to construct a turret head in such a manner
that the articles to be machined may be readily gripped and removed; and to
lock the revolving part of the head quickly and rigidly in the different positions 2
without the aid of a spring and in such a manner that the accuracy of the
division will not be affected by any wear and tear that may take place, and my
improvement consists in-improved arrangements for attaining said objects.
On the drawing appended hereunto
Figure 1 shews a vertical section through the improved turret head along the 2
dividing bolt;
Figure 2 a partial vertical cross section;
Figure 3 a plan;
Figure 4 a horizontal section along linex Figure 1;
Figures 5 a cross section of the dividing bolt;
Figures 6 and 7 cross sections of the sleeve for the same along lines Y Y
and Z Z on Figure 1.
The lower portion a of the head is formed with a base plate a¹ for bolting to
the machine table and is bored out conically on the upper and under side to receive
the revolving portion of the head formed of two parts b and c which are fixed
together by screws d' and fit accurately into the part a.
To the part a a sleeve d is fixed having an internal screw thread of course
pitch cut in the part and bored out to the outer diameter of the screw thread
in the part d². A bolt e with a handle h is provided which has an external screw
thread cut on it fitting the nut, and fits the sleeve in its front part and a hole in
the part a at the back part. Diametrically opposite parts of the thread on the
bolt and nut are cut away for rather more than a quarter of the circumference,
as shewn on Figures 5 and 6, so that when the threaded parts of the bolt are in
the spaces between the threaded parts of the nut, the bolt can slide in the
sleeve, but when the bolt is partly rotated the threads engage with each other
as in an ordinary screw. This device is commonly known as a "breech-screw."
The point of the bolt e is tapered as shewn and correspondingly tapered holes b
are provided in the revolving part of the apparatus into which the bolt enters.
To change the position of the revolving part the bolt is turned so as to disengage
the thread, a screw f being fixed in it and the sleeve cut out as shewn on

page_text: Figure 7 to determine this position by the contact of the screw and sleeve, then
pulled out, the part 6 turned as required, the bolt pushed in again and turned
to engage the threaded part. The position of the bolt required for this purpose
can be indicated by a mark on the part protruding from the sleeve, and the ends
of the threads on the bolt may be tapered to facilitate their entry into the nut.
In consequence of these arrangements the revolving part can be quickly and
accurately fixed in its different positions, any wear occurring on the end of
the bolt or in the holes being compensated by screwing the bolt further home.
Upon the revolving part 6 of the apparatus a cap or cover g is fixed by means
of the screws g¹. In the cap a circular groove preferable tapered outside is
formed centrally with the cone of the part 6. Into this groove is fitted a ring i
portions of which are cut away so as to form two eccentric cams, as shewn on
Figure 4. Handles 7 are fixed in the ring to turn it by. Across the revolving
part a groove with inclined sides is formed in which two blocks m and mi
slide. These blocks engage with the eccentric cams of the ring i in such a
manner that as the ring is partly turned the blocks are pushed towards or from
each other. Suitable dies n n for gripping the articles to be machined are
fixed to the blocks m m¹. Preferably the faces of the blocks are bored out
cylindrically when in their closing position, and the dies are formed in a solid
piece turned cylindrically in its lower part to fit the hore and with a flange on the
top to fix to the slide blocks by screws o o¹, and are afterwards cut through the
centre, the drawings shewing dies made in this way and arranged for gripping
a screw.
Instead of a handle for rotating the ring
a worm and wormwheel or a
toothed wheel and pinion may be used for this purpose.
The cap keeps the ring i in position and also prevents dirt or cuttings from
getting into the apparatus.
Having now particularly described and ascertained the nature of my
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. The construction of a turret head for milling machines and like tools and
the formation and combination of the parts thereof substantially as hereinbefore
described and illustrated by the drawings.
2. In turret heads for milling machines and like tools the arrangement of a
"breech-screw" and nut for fixing the revolving part thereof in its different
positions substantially as hereinbefore described and illustrated by the drawings.
Dated the 27th day of December 1899.
R. J. URQUHART, C.E.,
Chartered Patent Agent, Manchester & Liverpool.