Improvements in Screw-cutting Attachments for Lathes.
Year: 1899

page_text: Date of Application, 19th Dec., 1899 --Accepted, 30tn June, 1900
COMPLETE SPECIFICATION.
Improvements in Screw-cutting Attachments for Lathes.
I, JEAN CORNELIS, of 566, Rue St. Leonard, Liége, in the Kingdom of Belgium,
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:-
The object of the present invention is an apparatus or attachment for screw-
cutting, capable of being fitted to any lathe and able to finish at onc operation,
any screw-thread, whatever its form, depth and pitch may be, completely and
automatically.
In the annexed drawing, the complete lathe is shown, with the tool-rest, and
the screw intended to work the special form of screw-cutting tool. This screw
is preferably set in motion by gearing controlled by the lathe. This gearing,
as well as the screw to move the saddle forward and to move the tool rest support,
have no especial features.
Figure 1 is a plan view. Figure 2 a lateral view and Figure 3 a section
from A to B (Figure 1) of the saddle with the tool rest. In Figures 1 and 3
the tool is removed to facilitate the comprehension of the drawing. Figure 4
Of course
is a plan and Figure 5 a lateral view of a circular cutting tool
this varies according to the shape of the thread to be cut. Figure 6 is a plan
of a complete lathe upon a reduced scale.
. On one of the longitudinal sides of the lathe, and parallel to it, there is a
screw a, having its bearings in supports which are part of the structure and
controlled by gearing actuated by the mechanism of the lathe.
A worm wheel b
engages this screw a, and transmits its movement to the tool. This wheel b has
its bearing in an arm c affixed to the saddle d, which arm, surrounding the
screw serves as a guide for it. (Figure 2.) The worm wheel b is keyed to a
shaft f, which at its other end, is supported by the tool-rest g, and carries the
wheel h, which has tangential teeth and is adjustable only longitudinally along
this shaft f. This wheel h engages a like toothed wheel i keyed on the shaft 1,
the upper extremity of which carries either the rotating cutter or tool n, shown
in Figures 4 and 5, or any other suitable tool. The tool is retained on the
shaft by a nut m or other means.
The diameter of the wheel b is equal to the diameter of the tool n, the form
of whose teeth correspond to the thread to be cut.
The work t, to be screw-cut being fixed in the lathe at a suitable height, the
mechanism of the lathe is set in motion by means of the pulleys, which
directly drive the object to be threaded, and transmit their movement to the
toothed wheels q, q, q, and r, r, as in ordinary lathes. The wheels q, q', q²
are changed according to the thread to be cut and control the screw. The
screw s, which traverses the saddle in a direction parallel to the axis of the
The screw &
piece of work t, is driven through the medium of the wheels r, r¹.
turns and communicates its motion to the wheel b, and thence through the shaft f,
the wheels h, i and the shaft to the tool n.
Then the tool rest g. which is mounted on the saddle d and is moveable trans-

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versely to the length of the lathe, is advanced by the hand lever u until the
tool comes into contact with the work to be screw-cut and after starting the
traverse of the saddle d, by means of the screw as aforesaid, the
lathe is left to itself, and a screw thread of the required depth is formed
at one operation. The arrows shown in Figures 2 and 6 indicate the direction
in which the several parts are rotated in cutting a right-hand thread, and the
direction of traverse of the saddle d. The tool which is of disc shape, has on its
periphery teeth suitable for cutting or shaping the screw thread required.
In cutting a left hand thread, the work is rotated in the same direction, but
the direction of movement of all the other parts is reversed.
The thread is formed complete and cut to the desired depth throughout the
whole length of the work under treatment, in one operation, by the rotation
of the tool n, through the medium of the screw «, and the traversing of the
saddled by means of the screw s; it being understood that the teeth of the tool
get to work successively and each removes a small portion from the object to be
screw cut. It is not necessary to keep the tool cool but it is preferably to lubri-
cate the work to be screwed.
By means of this lathe attachment any form and pitch of screw-thread may
be cut by changing the tool and the wheels y and 2 as in ordinary screw-cutting
lathes.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
In a screw-cutting lathe, provided with a rotating tool or cutter, driving
the tool by means of ordinary lathe-gearing operating an endless-screw («),
which transmits its motion to a worm wheel (b) keyed on a shaft (f), carrying
another worm wheel (h) moveable longitudinally on its shaft and engaging a
corresponding wheel (2) on the spindle of the tool, substantially as and for the
purpose herein described and also as set forth in the accompanying drawings.
Dated this 18th day of December 1899
JEAN CORNÉLIS.
By Henry Skerrett,
24, Temple Row, Birmingham, Agent for Applicant.