IMPROVEMENTS IN THE MANUFACTURE OF VULCANIZED INDIA-RUBBER THREAD
Year: 1862

page_text: LETTERS PATENT to Thomas Barnabas Daft, of No. 2, Queen Square,
Westminster, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE
OF VULCANIZED INDIA-RUBBER THREAD."
Sealed the 16th January 1868, and dated the 17th July 1862.
PROVISIONAL SPECIFICATION left by the said Thomas Barnabas Daft at
the Office of the Commissioners of Patents, with his Petition, on the
17th July 1862.
I, THOMAS BARNABAB DAFT, of No. 2, Queen Square, Westminster, do
hereby declare the nature of the Invention for "IMPROVEMENTS IN THE MANU-
FACTURE OF VULCANIZED INDIA-RUBBER THREAD," to be as follows:-
This Invention has for its object improvements in the manufacture of
vulcanized india-rubber thread. Heretofore vulcanized india-rubber thread
has been made with flat sides, and of a rectangular or square section, and in
consequence thereof the angles are very liable to be jagged or ruptured. Now,
according to this Invention, vulcanized india-rubber thread is made of n
circular section, or as nearly so as may be without angles. The india-rubber.
used for the purpose is ground or masticated with a proper quantity of sulphur.
to cure the thread made therefrom when such thread has been subjected to
the requisite process of heat. A pair of grooved rollers are used, the grooves
of which are semicircular, and come close together, they being divided by.
sharp edges, the sharp or thin edges of one roller coming in contact with those
of the other roller. The plastic compound of india-rubber and sulphur is

page_text: passed between the rollers, and the several threads aro received on to separate
rcels, bobbins, or holders, the several coils thereof being kept separate, or so
dusted or coated with chalk or lime, or other suitable powder as to prevent
the parts adhering. The thread is then subjected to heat in the well-known
manner to cure or convert the same. It is not essential that the edges which
divide the grooves one from the other should be so sharp as actually in the act
of rolling to divide or cut the plastic india-rubber compound into separate
threads, as the edges, though thin, may be blunt, so that a sheet of compound
will be produced consisting of rounding ridges and furrows, such sheet
requiring to be cut to divide the parallel threads one from the other.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Barnabas Daft. in the Great Seal Patent Office on
the 16th January 1863.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
BARNABAS DAFT, of No. 2, Queen Square, Westminster, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Seventeenth day of July, in the year of our Lord
One thousand eight hundred and sixty-two, in the twenty-sixth year of Iler.
reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Thomas Barnabas Daft, Her special licence that I, the said
Thomas Barnabas Daft, my executors, administrators, and assigns, or such
others as I, the said. Thomas Barnabas. Daft, my executors, administrators,
and assigns, should at any time. agree with, and no others, from time to time
and at all times thereafter. during the term therein expressed, should and
lawfully might make, use, exercise, and vend; within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an Inven-
tion for "IMPROVEMENTS IN..THE MANUFACTURE OF VULCANIZED INDIA-RUBBER
THREAD," upon the condition (amongst others) that :I, the said Thomas
Barnabas Daft, my executors. or administrators, by an instrument in writing.
under my, or their, or one of their hands and scals, should particularly
describe and ascertain the nature of the said. Invention, and in what manner
the same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said Thomas Barnabas Daft, do hereby
declare the nature of the said Invention, and in what manner the same. is to

page_text: be performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say :—
The india-rubber used for the purpose is cleaned, ground, and mixed with a
proper quantity of sulphur to cure or vulcanize the thread made from the
mixture when it has been subjected to the requisite process of heat. The
sheet produced from this compound of india-rubber and sulphur may bo
spread in the usual way in which sheets are made for the purpose of being
vulcanized, and afterwards cut into thread, and which process of spreading is
well known; or it may be produced by simply rolling out the compound after
it has been well blended and mixed, or otherwise suitably prepared, which
processes are also all well known. A sheet of sulphurized india-rubber, either
spread or rolled to about the thickness of the diameter of the thread required
to be made is cut up into strips of the full length of the sheets, and of a
suitable width for the apparatus herein-after described. If the sheets be of
great length the thread will be in proportion, if short, the thread will be short
also; but if very long lengths of: thread be required, and it be inconvenient to
spread sheets accordingly, or to roll them out of the requisite length desired,
then one sheet may in. the sulphurized state be readily joined endwise to
another, and in this way, or by similarly joining the strips of a few inches wide
endwise, the means of obtaining thread of any desirable length will be obvious.
India-rubber compound fresh from the spreading or rolling is liable to shrink,
particularly when the compound of india-rubber and sulphur is of the best
and purest materials, such as should always. be used in the manufacture of
thread, and it is preferred that it should be submitted to a setting or seasoning
process; time will effect this at ordinary atmospheric temperatures, but it may
be readily done by submitting it to the effect of boiling water for a short
period, according to the bulk of material being opérated on; or if water under
pressure, or steam at 250°, or thereabouts, be employed to set it, a still shorter
time serves to season, set, or shrink it. In seasong or setting sulphurized
sheet or strips by boiling, if the same be done under pressure, it is necessary
to caution the operator not to. carry the process too far, that is to say, not to
semi-vulcanize it, or the effect will be when put through the rollers to cut and
separate the strip into threads with only rounded sides, the angles being less
rounded off. If the strips of india-rubber compound are by accident or other-
wise completely vulcanized, then by the machine herein described vulcanized
india-rubber thread will be produced of; a less rounding and of a more square
section, although the passages through the rolls are circular or eliptical; but
there will even under these circumstances be a marked improvement over the
ordinary square-sectioned thread cut in the ordinary manner. The time and

page_text: heat will very soon be accurately judged of by a workman accustomed to such
processes. The sheets or strips being well seasoned, are now to receive a
dusting of powdered "French chalk," which may be lightly rubbed on the
surfaces, in order to prevent adhesion in the process of reeling or winding
the strips upon feeding pullies. :
A pair of steel grooved rollers A, A, of about two inches diameter and two
inches long on the face or barrel are mounted in suitable frames B, B; the
rollers are formed with corresponding semicircular grooves varying, say, from
the 10th to the 50th of an inch in diameter, and when such rollers are made
to come close together they will shew circular spaces or passages between
thom; but it is better that this should not be exactly the case, although it is
found that if perfectly semicircular grooves be made in each roller, and the
division between each groove be a mere sharp or knife edge, round india-
rubber thread can be produced, provided always that the rollers be made
perfectly true, of a good spring temper set accurately, so that the sharp edges
of one roller come in contact during the complete revolution with the other,
yet it is better to have the grooves about one-fourth of their width or diameter
deeper than the semi-diameter, and about one-fifth of their diameter asunder,
that is to say, that they shall be so far from centre to centre of their "pitch"
lines as to leave an edge of one-fifth, or thereabouts of the width of the
grooves between each groove instead of a sharp or knife-like cutting edge.
And it is preferred that the rollers should be so mounted in a frame or frames,
as that when in position, either mounted between centres or on journals, they
may be lapped or turned true by tools actuated by an "over-head motion," or
otherwise, or the rollers may be so arranged as that one part of the frame C, C,
having one roller mounted upon it may be easily removed, and allow of
adjustment by suitable machinery, whilst a similar operation may be brought
to bear upon the other.
It will be obvious that by having the grooves in the rollers deeper than
half the diameter a lapping or reducing process of the rollers may be
resorted to occasionally, in order to obtain and maintain perfect cylindrical
accuracy without impairing the width of the grooves, and there is another
advantage in such arrangement, namely, the thread is found more circular in
section from rollers forming slightly elliptical openings than from those having
perfectly circular ones; there is, in fact, a minute tendency. under vulcaniza-
tion of the thread to flatteu a fraction in the depth or thickness way of the
sheet, and by a judicious enlargement of the grooves in the right direction the
proper compensation is made, and round thread produced, after it has gone
through the process of vulcanization. It might appear difficult to cut or

page_text: clearly divide the threads one from the other with rollers having comparatively
broad or blunted edges, but it is perfectly easy when the rollers are of them-
selves quite true, accurately set with reference to meeting each other, and
with a proper degree of pressure the one against the other, to cut the plastic
or semiplastic material to be dealt with perfectly and completely into distinct
and separate threads. In order to ensure a regular pressure of one roller
against the other; one roller is mounted in fixed centres or bearings B, B,
permanently attached to or being part of the principal frame, and the other
roller is mounted on centres or bearings C, C, belonging to a separate frame D,
made so as to allow of being fixed on centres or bearings attached to the
principal frame, and by a lever motion and adjustable screw E acting upon a
plate F, supported by an elastic bed G, a certain. degree of pressure with an
amount of resiliance is imparted to the roller, which is moveable in in its
frame. There is a double advantage in the resilience thus provided; firstly, any
very minute eccentricity of the rollers is thereby rendered harmless, or, in fact,
nullified so far as its effects in thread-making go; and secondly, if by accident
any hard body gets between the rollers there is much less danger of damage
being done to them. Assuming now that the rollers are mounted and in
perfect order, they are to be geared by toothed wheels or otherwise, and made
to turn at a speed at from 50 to 100 revolutions per minute. "Overhead" is
arranged a frame to receive a feeding pulley before mentioned, charged with a
strip of the india-rubber compound of, say, 60 or 100 yards long by two inches
wide and of an inch thick, which has been set or seasoned, and served with
French chalk dust, and carefully wound on the pulley, in order that when the
latter be properly suspended at a convenient distance over the rollers it may
be made to freely feed the rollers with the strip of india-rubber thread com-
pound. The end of the strip being placed between the rollers, and a guide
arranged for the purpose of bringing it correctly to the rollers, being made to
bear upon the strip, motion is given to the rollers, which immediately take hold
of the strip and convert it into threads; these are allowed to pass through the
.bottom of the machine (an aperture H being left for that purpose), or they
may be carried under one of the rollers; in either case they are conducted to
separate reels, but I prefer to conduct them to a receiving drum of about
three feet diameter, turned by hand or otherwise, at a speed so as to take up
the threads loosely, and at the same time dust them with French chalk, other-
wise they may be passed through a mixture of French chalk and water by the
lower part of the receiving drum working in a trough containing a mixture of
the kind calculated to separate the threads and to fill up the interstices between
them. The receiving drum should be of metal or material suitable to stand

page_text: -inch
the heat necessary for vulcanizing the thread. The loaded drum may stand
-for a time in order to set or season the thread, say for. a day before subjecting
the thread to the curing process; this tends to secure the desired shape or
.section of thread. Rollers of about two inches on the barrel; with
grooves and blunt cutting edges in proportion, as herein-before described
would give about 25 threads, and I prefer to produce about that number by a
.pair of rollers, but do not confine myself to that or any greater or less numbers,
nor to the diameter. or length of the rollers, nor to the material being steel or
.chilled iron, as other materials may be used.. By arranging for a circulation
of steam or hot or cold water through one or both of the rollers, the usual
effect: of..a tendency of the india-rubber compound. to leave the rollers in a
certain direction is obtained..
I prefer the rollers turned out of the solid, but they may be made up of
steel discs, which would have to be pierced in their centres, and put upon a
spindle made to admit of them' being screwed up very tight. The advantage
of such an arrangement is, that a defective disc may be replaced without
discarding the whole. One of the rollers may be of hard or semi-hard india-
rubber compound, which allows of the edges of the steel roller to slightly
penetrate.or embed themselves into the elastic surfaces of the india-rubber
compound, and I. find that by giving a great speed to the steel roller, par-
<ticularly when the edges are made sharp, and a slow speed to the india-rubber
¡compound roller; the separation of the threads is very complete; in this
process I find it advantageous to use water....When knife-like edges are
made to project considerably above the bottom of the grooves either from
solid rollers or rollers made up of steel discs,. and actuated at different speeds
-or upon elastic surfaces; there is a tendency to produce only partly rounded
thread from sulphurized india-rubber compound, and if the india-rubber
compound be vulcanized the thread cut from it by such last-mentioned process
would be angular in section. In either case I prefer to have the number of
grooves ranging from 20 to 30, and the receiving drum is better not to be
loaded with more than about 25 threads, each from.100 to. 200 yards long.
The curing chamber. I prefer to be a cylinder arranged vertically, and so as to
receive in a cage or frame 20 of such drums at a charge, the same being
lowered into water, and the heat gradually got up and maintained until
vulcanization has taken place; this process of vulcanization is well known.
After vulcanization the thread is to be unwound from the drum, and made up
into skeins, the chalk being removed by an application of boiling soda or
caustic potash in the usual way...If.it. be required to keep the 25 or any
other number of threads: made from one strip altogether, so as to save trouble

page_text: in the skeining operation, or for any subsequent purpose it is only necessary to
separate the rollers and pass a quarter of an inch or so through before com-
municating rotatory motion to them, and then the pressure and motion being
put on must be continued until within the same distance, inch or so of the
other end, when the revolving motion must be stopped, the rollers separated.
and the strip taken out, which will thus have what may be termed selvage
ends. Of course any number of such blank pieces as would be at the ends of
this strip may be left intermediate, dividing each strip into a number of
sections of 25 threads of any fixed lengths.
The rollers may be made with the edges coming in contact still more
blunted than has been described, or they may be set so as not to quité touch
each other or to touch, but so that the resilience existing in the one frame
shall allow of a strip passing the rolls and not quite severing the rubber; in
either of these cases the object is to obtain a sheet or strip of india-rubber
compound, consisting of rounded ridges and furrows, and this may be passed on
to the receiving drum in a slack manner, and served with a coating of chalk
to fill up the interstices and to prevent adhesion, and then vulcanized and cut
into threads by rollers having suitable guides for conducting such a fabric to
them, or a sheet or strip of ridge and furrow material may be passed again
through rollers adjusted so as to completely divide it into threads.
In witness whereof, I, the said Thomas Barnabas Daft, have hereunto
set my hand and seal, this Fifteenth day of January, in the year.
of our Lord One thousand eight hundred and sixty-three.
THOMAS BARNABAS DAFT. (L.S.)