IMPROVEMENTS IN OR RELATING TO MACHINERY OR APPARATUS FOR CHASING OR CUTTING SCREWS WHICH IMPROVEMENTS ARE ALSO APPLICABLE TO OTHER PURPOSES
Year: 1884

page_text: I WILLIAM NIBLETT of the City of Bristol do hereby declare the nature of the
said invention for IMPROVEMENTS IN OR RELATING TO MACHINERY OR APPARATUS
FOR CHASING OR CUTTING SCREWS WHICH IMPROVEMENTS ARE ALSO APPLICABLE TO
OTHER PURPOSES," and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :-
My said invention, which is designed to obviate irregularity in cutting the
threads of chased screws cut by hand tools and in the production of designs on
turned articles, consists in the employment, in a lathe or other turning machine, of
a ring or plate capable of being adjusted, upon its support or supports, obliquely
to the axis of rotation which is the same as that of the mandrel of the lathe or
other turning machine.
Against the face of the inclined ring or plate which is rotated at a slower speed
than the material to be operated upon, is held a roller centred on one end of a bar
which carries at the other end the chasing or cutting tool. In rotating, the ring
or plate, acting as a swash plate, imparts motion horizontally to the tool bar, and,
on the application of the tool to the material to be operated upon an even and
regular series of incisions is produced which may be subsequently continued
independently by the operator throughout the length of the work. The ring or
plate may be driven direct from the mandrel or it may be centred on a spindle
actuated by the mandrel.
The horizontal travel of the tool bar for a given extent of rotation of the ring,
and accordingly the pitch or number of screw threads is governed by the inclination
at which the ring or plate is set, and may be indicated upon a graduated scale or
index affixed to the apparatus.
And in order that the said invention may be properly understood, I now
proceed inore particularly to describe the same with reference to the accompanying
sheet of illustrative drawings and the figures and letters marked thereon.
Fig. 1 on the accompanying sheet of Drawings represents a front elevation of a
turning lathe having my improved apparatus applied thereto.
Dlan of the cuine

page_text: The ring, a, pivotted at o upon the drum or collar, b, is capable of being inclined
on its pivots so as to cause the outside face thereof to be presented in an oblique
position to the roller, c, centred on one end of the tool bar, d, hung at that end
upon the rest bar, g. At the opposite end of the tool bar d is the screw chasing or
cutting tool c. The ring or plate, a, is placed concentrically with the mandrel by
which it is rotated. It may, however, be centred on a spindle actuated by the
mandrel. The ring or plate, a, driven at a slower rate of speed than the
material being operated upon by means of suitable gearing which, when the ring
or plate, a, is placed concentrically with the mandrel may be conveniently enclosed
in the drum or collar, b. At Fig. 3 is illustrated a form of sun and planet gearing
which may be adopted for this purpose.
Rigidly fixed to the mandrel, l, is the eccentric, r, embraced by the planet
wheel, s, gearing with the teeth with which the interior of the drum, b, is provided.
The drum is not rigidly fixed to the mandrel.
The rest lar, y, is inade to engage with the jaw or slot formed for that purpose
at one side of the Planet wheel, s, and the latter being thus brought into action
produces the following effect. The teeth of the planet wheels, being of the same
pitch as, but less in number than, the teeth of the drum, b, are caused by the
eccentric motion to gear one after the other with the teeth of the drum, b, and the
latter is thereby moved round in one revolution of the eccentric, r, to the extent of
the difference due to the excess of teeth of the drum, b, to which the ring, u, is
pivotted as aforesaid.
I do not confine myself to the use of a particular form of gearing to produce a
motion of the ring or plate, a, slower than that of the material being operated
upon.
The roller c (Figs. 1 and 2) is held against the outer face of the ring, «, which,
acting as a swash plate, imparts horizontal motion to the tool bar, 7, alternately
towards each end of the machine. Thus, throughout a part of its revolution, the
ring, causes the tool bar, d, to be impelled from right to left, and on the
application then of the tool, e, to the material to be operated upon the chasing or
cutting of a "right-hand" screw is commenced. When, as the ring, u, rotates,
motion to the left ceases the bar, d, is drawn, independently by the operator, still
towards the left, provided the length of screw requires it, the threads first cut
serving as guides to produce an even series of threads or incisions throughout the
length of the screw.
In order to cut a "left-hand" screw, the tool, c, is applied as the bar, d,
commences, in the rotation of the ring, a, against which the roller, c, is held as
aforesaid, to be moved from left to right, and if it be required to continue cutting
after the motion in that direction ceases, the tool bar, d, is unhung from the rest
bar, g, and dispensed with, the cutting being continued independently by the
operator with a simple hand tool. The threads or incisions first cut serve as
guides for the tool in the continuation of the cutting.
My said invention is also applicable to the production of ornamental or fanciful
designs on certain articles. For this purpose the outer face of the ring or swash
plate, a, is dentated or otherwise similarly furnished with a desired design or
pattern and the proper tool is substituted for the screw chasing or cutting tool, c.
The design is produced upon the material supported in the lathe, by the application
of the roller c to the inclined face of the ring, a, a varying motion being imparted
to the tool according to the nature of the pattern on the face of the ring, a.
The horizontal travel of the tool bar & for a given extent of rotation of the
ring or swash plate, a, is governed by the inclination to which the latter is set
and may be indicated upon a graduated scale or index affixed to the apparatus.
Motion of the tool bar, d, in one direction throughout an entire revolution of
the ring or swash plate may be obtained by dividing it as seen at Figs. 4 and 5,
which represent respectively a side elevation and plan of the drum or collar, b,
carrying the ring, a, so divided. The divided ring or strap, a, is fixed to the
drum or collar, b, at a point opposite to the division and the ends are drawn apart

page_text: and are adjusted on the periphery of the drum or collar & by the clamping screws
or bolts, m, which are themselves adjustable in grooves, n, sunk in the drum or
collar, b, to receive them. The divided ring or strap, a, thus resembles a thread
of a "right hand " screw, and on the application thereto of the roller of the tool
bar, motion of the latter towards the left would be produced throughout a
revolution. By reversing the respective ends of the divided ring or strap a so as
to cause the latter to assume the form of a thread of a " left-hand screw,
motion of the tool bar towards the right would similarly ensue. The ring or
strap a may be made up of one piece or of two or more pieces.
By withdrawing the rest bar (Figs. 1, 2, and 3) from the jaw of the planet
wheel the machine is reconverted for use as an ordinary lathe.
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 :-
The employment, in a lathe or other turning machine, of the adjustable ring or
plate a, undivided arranged and acting as herein before described with reference to
Figs. 1, 2 and 3 of the drawings, or divided, arranged and acting as described
with reference to Figs. 4 and 5, to produce horizontal motion of the tool bar d;
the said ring or plate a being rotated at a slower speed than the material being
operated upon, substantially as, and for the purposes, specified.