Improvements in Screw Cutting Lathes.
Year: 1896

page_text: PROW SIONAL SPECIFICATION.
Improvements in Screw Cutting Lathes.
I, WILLIAM TAYLOR, of Slate Street Works, Leicester, in the County of
Leicester, Engineer, do hereby declaro the nature of this invention to be as
follows:-
My invention relates to lathes employed chiefly for cutting short screw threads,
my object being to effect the cutting of the threads rapidly and yet with great.
accuracy.
For this purpose, I mount the mandril head, which carries the work, on a
spindle parallel to the mandril so that it can rock to and fro, in one position
resting against stops and presenting the work to a stationary cutting tool and
moving lengthwise as determined by a guide screw; in the other position
removing the work from the tool so that the head can be moved back for the
work to be operated on again. The rocking and return movements may be
effected in whole or in part by hand; I prefer however to effect them auto-
matically by suitable connection with the continuously revolving mandrel.
Thus, for instance, on the head having made a predetermined traverse while
the guide screw is driven from the mandrel and the thread is being cut, it is
rocked by an excentric or its equivalent so as to remove tho work from the cutting
tool, and thereupon the guide screw is disconnected from the mandrel, and a
weight or spring wound up by it while the thread was being cut moves the guide
sorew backwards and thereby slides the head back. The head then being rocked
back and the guido screw again engaged with the mandrel, the thread cutting
operation is repeated.
Dated this 19th day of November 1806
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Screw Cutting Lathes.
I, WILLIAM TAYLOR, of Slate Street Works, Leicester, in the County of
Leicester, 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:-
My invention relates to lathes employed chiefly for screw cutting, my object
being to effect the cutting of the threads rapidly and yet with great accuracy.
I shall describe the construotion and arrangement of a lathe head for this
purpose, referring to the accompanying drawings,

page_text: Figure 1 is a side clevation, Figure 2 is an end elevation, and Figure 3 is a
plan of a lathe head according to my invention.
The mandrel with its pulleys A and nose P by which the work is attached is
mounted as usual in bearings in the mandrel head or frame Z which is mounted
on a rocking shaft G so that it can rock within certain limits, in the one position
against stops which project up from the bed, and so that it can also slide or
traverse endwise as determined by the guide screw B upon the mandrel when
engaged with the part nut C which is fixed adjustably on the upper arm of a
bent lever D, the lower arm of which has a gap engaging an eccentric on a
spindle E which can be turned by a handle e. On this spindle which extends
some distance into the bed is another eccentric which as the handle e is turned
to remove the part nut C from the guide screw B moves up a stud F which locks
the head against the stops H in position for plain turning.
On the mandrel is fixed a pulley I which by means of a band drives a pulley
and spindle in any convenient position, this by a return band driving a pulley J
which is mounted with a friction washer on a spindle K. The spindle K has
on it two projecting pins which when the spindle revolves, come to bear
against a pin L3 on a sliding piece L which thus stops the spindle in either of
two positions, the pulley J nevertheless continuing to revolve and tending by
friction to move the spindle when it is free to move. The two pins projecting
from the spindle are so placed that they are stopped alternately by the pin in
the sliding piece L when it is moved to and fro. (In the spindle K there is an
eccentrio which, as the spindle turns, raises and lowers a catch N¹ engaging a
rib or claw projecting from the mandril head Z, and thereby causes the head
to rook backwards and forwards on its rocking shaft G.
The sliding piece L has a pin L' engaged in a gap in one arm of a lever M
pivotted on the head Z, the other arm of the lever coming to bear against tho
pulley I.
The operation is as follows:-
Assuming the head to be in the position shewn, the work to be screwed being
attached to the mandrel, and a cutting tool suitably supported behind the work,
the lever e is moved so as to release the stud and bring the part nut C in
engagement with the guide screw B; then as the mandrel revolves backwards
and traversos, cutting a screw on the work, the head retreats until the projection/
adjustably attached to the head Z moves the sliding piece L and permits the
spindle K to turn partly round lowering the catch and rocking the head so
as to withdraw the guide screw B from the part nut C (and the work from the
cutting tools). The mandrel then continues to revolve but ceases to traverse,
and in this condition the head is free to be slid back to its starting position,
either by hand or by a weight or spring up to a suitable stop.
In order to deaden the shock when the head reaches the stop, one hearing of
the head on the rocking shaft G Figure 2 is fitted with a cover to enclose the
air which is thus compressed by the motion of the head but is permitted to
escape through a small hole regulated by a screw.
The head in thus returning to its stop moves the lever M until it bears against
the face of the pulley I whereupon the gap of M draws forward the sliding
piece L and the piece X projecting from the pulley I moves the lever M and
the sliding piece L and completes the disengagement of the shaft K at the time
when the threads of the guide screw B and the part nut Care in position to
re-engage.
The spindle K then turns partly round again and, by means of excentric N,
rooks the head back so that the guide sorew B again engages with the part nut C
and the operation is repeated.
The projection is made adjustable and graduated to indicate various lengths
of traverse of the head.
It will be obvious that for traversing the head, instead of causing it to slide
upon the axis on which it rocks, it might be mounted with its rocking axis on

page_text: centres upon a plate to which the traversing motion is imparted, but I prefer
the arrangement described as being simpler.
Having now particularly described and ascertained the nature of my said in-
vontion and in what manner the same is to be performed I declare that what I
claim is:-
1. A head for a screw cutting lathe arranged so as to be capable of receiving
both a rocking and a traversing motion, substantially as described.
2. In a head for a screw cutting lathe, the combination of means for traversing
the head with means for imparting a rocking motion thereto, by an excentric or
equivalent motion, so arranged as to operate intermittingly at right times,
substantially as described.
3. A rocking and travorsing head for a screw cutting lathe combined and
operating as herein described with reference to the accompanying drawings.
DL: 1711 dave of tu 1807
ABEL & IMRAY,
Agents for the Applicant.