Improvements in Machines for the Manufacture of Screw-nuts.
Year: 1896

page_text: Date of Application, 25th Jan., 1896-1ccepted, 4th Apr., 1896
COMPLETE SPECIFICATION.
Improvements in Machines for the Manufacture of Screw-nuts.
I, FRIEDRICH AUGUST MEISCHNER, Mechanical Engineer, of Klosterstrasse,
Chemnitz, in the Kingdom of Saxony, 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:-
This invention relates to machines for tapping screw-nuts, and has for its object,
to construct the same in such a manner that it is only necessary to supply the
machine periodically with about one thousand or two thousand crude nuts arranged
in piles, after which the machine automatically provides the nuts with screw-
threads, and allows them to drop out at the bottom. As the quantity of screw nuts
fed into the machine at one time will last for a whole day, the same workman will
be able to attend to several machines.
In the accompanying drawings,
Fig. 1 is a vertical section of a machine embodying my invention;
Fig. 2 is a plan of one half of the machine;
Fig. 3 is partly a side elevation of the machine, and partly a vertical section
through the driving gear;
Figs. 4, 5, 6, 7 and 8 show in what manner the nuts are conducted to the
screw tap;
Figs. 9 and 10 illustrate the method of operation of the tap.
The machine comprises in its construction a revolving vertical shaft a, on which
are fixed a pair of discs b', 62. The disc ' has radial recesses for suspending
vertical bars c, and the disc 2 has perforations wide enough to allow the untapped
nuts to pass through; said perforations being situated vertically under the recesses
of the disc b'.
Close underneath the disc b # plate d is fixed to the machine frame; which
plate has circular openings o', o, placed vertically above the screwing taps e', e³,
and provided with slides o,*, o, for closing the same.
For the sake of simplicity the bars c are preferably suspended in revolving discs,
as shown, but they may be suspended in a reciprocating frame adapted to place the
bars over the openings o', o² one by one, and to deliver the nuts in the required
manner.
The upper part of each tap has two pairs of parallel faces filed on, the vertical
distance between which is equal to the height of the largest screw nut to be tapped.
Over these faces slide alternately the bolts 91, 92; 91, 92, drawn by the springs f
in the direction of the arrows; said bolts serving to prevent the taps from dropping
and turning; they are shifted by rollers i, i, ix, x, fixed on a disc / which is
mounted on a slowly revolving hollow shaft w₂, this being done in such a manner
that the semicircular recesses will be placed opposite each other at the required
time, and that the nuts m lying on the bolts may then fall through the same, as
indicated by Figs. 4 to 8.
All the nuts mounted on one of the rods c descend for the height of a nut, when
passing the aperture o, (see Fig. 6) and the lowest nut is held back by the vertical
wall of the said aperture o₁ and the conical part of the tap. As the bar c
continues its motion (being propelled by the edge of the aperture in the disc b₂) the
other nuts separate from the deposited nut and are lifted by the inclined edge k of
the slide o* (Figs. 7 and 8). The height should be greater than that of the

page_text: largest nut to be tapped, and
to be tapped.
should be less than the height of the smallest nut
As soon as the bolts g g have assumed the position shown in Fig. 5, the
deposited nut drops between the bolts on to the bolts g, g" (Fig. 8), and after
the bolts g, g, have again seized the screwing taps, the slides g, 9 assume such
a position, that the nuts lying on the same drop along the spindles of the screwing
taps, until they reach the screw-threads of the same. The screwing tape is
suspended within the hexagonal or square interior of the sleeve & held up by a
spring, so that the nut dropping into the said space or interior is obliged to take
part in the rotary motion of the said sleeve, which is imparted to it by the sleeve
surrounding the sleeve k', the latter being connected with the former by steep
screw threads, as shown in Fig. 11. This arrangement has for its object, to enable
the screwing tap to cut the nut, for if the sleeve k could not take part in the down-
ward motion of the nut m, which occurs during the thread-cutting, the nut would
be held back by the sleeve through friction, and would only be bored out. For
utilizing the frictional contact between nut and sleeve to start the cutting of the
thread, the sleeves and are not coupled by vertical grooves, but by grooves
forming steep helices (Fig. 11), in consequence of which the cut is started as
follows:-
The nut falling into the sleeve is held by the same, and the cutting teeth of
the tap which immediately begin to bite, oppose a resistance to the turning of the
nut, which is sufficient to start the downward motion of the sleeve k. Owing to
the frictional contact between the sleeve k' and the nut to be tapped, the vertical
shifting of the sleeve is communicated to the nut, and this latter is pressed still
more firmly against the screwing tap. In consequence of this increasing resistance
between the screwing tap and the nut, the downward pressure of the sleeve
and of the nut to be tapped increases also, and this causes the tool to act on
the nut.
The pitch of the screw-threads of the sleeve and of the hollow spindle ³, and
the tension of the spring f', are chosen in such a manner, that the nut to be tapped
and the sleeve will move downward together, until the sleeve k' rests on the
ring. This latter is hexagonal or square inside, and is secured to the hollow
spindle. The thread of the nut has now already been cut so deeply that during the
further tapping of the nut the strength of the screw threads exceeds several times
the frictional resistance encountered by the nut in sliding down the interior of the
sleeve k².
Before the nut leaves the sleeve, it is held by the ring &, fixed in the sleeve ³,
and thus the tapping is completed.
For supplying the soap water necessary during the process of cutting the thread,
a feeder Vis mounted above each of the cutting devices; said feeder receiving soap
water from a pump driven by the main shaft of the machine and ejecting it towards
the screw tap in several jets.
The machine receives its motion from a main driving shaft w, provided with a
fast and loose pulley and adapted to turn a spur wheel 3 by means of bevel
wheels, . The spur wheel is loose on a hollow axle w² and gears into spur
wheels,, mounted on the sleeves 2. On a horizontal shaft w³ geared together
with the shaft w by means of tooth wheels, r, there are mounted a pair of
worms S1, S2, the worm s₁ serving to set in motion the hollow shaft w, by means of a
worn wheel, while the worm s, gears into the worm wheel mounted on a
shaft w which imparts a slow rotary motion to the spindle a by means of a worm s³
and worm wheel 10.
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 :
1. A machine for tapping screw-nuts, comprising in its construction a series of
suspension bars on which the crude nuts are piled, and which are adapted to deliver

page_text: the lowest nuts as they pass the cutting device, so as to conduct them towards the
screwing taps, substantially as described.
2. In a machine for tapping screw nuts, the device for facilitating the
commencement of the cutting process, comprising a pair of sleeves k₁ k, adapted to
slide one within the other along steep screw threads, the inner sleeve having a
hexagonal or square central opening and the outer sleeve being provided with
means for imparting to it a slow rotary motion, a spring f1 adapted to be
compressed by the downward motion of the sleeve k₁, and a hexagonal or square
ring k adapted to revolve with the sleeve k₂ and to limit the motion of the
sleeve ki, substantially as described.
3. In a tapping machine adapted to feed the crude nuts by depositing or
dropping them one by one from suspension bars, a screwing tap having a spindle
adapted to receive the nuts and to guide them towards the cutting thread so as
to prevent the tilting of the nuts on their way to the same, substantially as
described.
Dated this 25th day of January 1896.
FAIRFAX & WETTER,
433, Strand, London, Agents.