Improvements in the Manufacture of Inflatable Air Tubes for Pneumatic Tyres.
Year: 1895

page_text: Date of Application, 5th Jan., 1895-Accepted, 9th Feb., 1895
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Inflatable Air Tubes for
Pneumatic Tyres.
I, ALBERT EDGAR ALEXANDER, of 19 Southampton Buildings, Chancery
Lane, in the County of Middlesex, Chartered Patent Agent, do hereby declare the
Dature of this invention (communicated to me from abroad by Fred William
Morgan, of 339 West Lake Street, Chicago, Cook County, Illinois, in the United
States of America, Rubber Manufacturer) and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
Prominent objects of the invention, are to produce a light durable and seamless,
inflatable air-tube for pneumatic tires involving a high degree of perfection; and
to attain results with certainty, and in an economical, rapid and highly efficient
way.
To the attainment of the foregoing and other useful ends, a sheet of adhesive
rubber film is first formed of unvulcanized rubber, and from this is cut a sheet of
such width and length relatively to the proposed size and thickness of air-tube to be
produced, that it can be rolled upon and about a mandrel so as to form a seamless
multiple-ply or multiply (as it may be termed) tube, of proper size and thickness.
The provision of this sheet of rubber film ensures a greater uniformity of perfection
than is found in sheets of rubber of the thickness commonly adapted in the manufac-
ture of air-tubes for pneumatic tires, it being extremely difficult and in fact not a
practical matter to produce perfect calendered sheets of the thickness commonly
used for tube making. On the other hand however, sheets of pure rubber film of,
for example, one thirty-second or one sixty-fourth of an inch in thickness can be
rolled out so as to involve a high degree of perfection and integrity of texture
throughout. The rubber film thus produced is however, delicate, filmy and sticky,
and hard to handle. In order to handle this rubber film with ease and rapidity,
and also to readily and rapidly roll the same into a multiply tube devoid of air-
bubbles between its plies or layers and possessing in general a high degree of
perfection and general adaptability for long service, the sheet of unvulcanized
rubber film is rolled upon and about a mandrel and also upon itself to an extent to
form a multiply tube, and while thus rolling the film into tube form, it is subjected
to an elastic yielding pressure or resistance in opposition to the mandrel, so as to
directly unite the plies or layers of film smoothly and evenly and exclude air from
between them. In order to successfully attain such yielding elastic pressure and
resistance and at the same time ensure rapidity and perfect work, an elastic yielding
bed or cushion table is provided and upon this the sheet of film is laid in a spread
out condition. The mandrel which is then employed, is simply a long cylindric
stick, which may be termed an independent mandrel for the reason that it is by
itself and free to be handled by and at the will of the workmen. The mandrel is
then rolled over the sheet by several operators with suitable manual pressure, which
in effect secures in opposition to the mandrel an elastic yielding pressure or resis-
tance. The film being thus rolled directly upon itself and being adhesive and
perfectly pliable, will readily wrap about and conform to the shape of the mandrel,
and hence, when the mandrel is rolled over the sheet, it will at the start take the
film and roll up the same during the initial portion of the operation of rolling
the mandrel upon the film whereby the first ply or layer is formed directly upon
the mandrel, the elastic yielding surface upon which the film is first laid, is

page_text: noticeably of greater advantage than a hard, unyielding surface, since by exerting
moderate down pressure upon the mandrel, the film will be compressed between the
mandrel and an elastic or spring yielding surface which will yield under pressure
along the length of the mandrel and thereby cause the film, as a condition both
desirable and precedent to the formation of the succeeding ply or plies, to wrap or
roll smoothly and evenly upon the mandrel. During the formation of the succeeding
ply or plies, the compression between the first ply or layer and the elastic yielding
surface of the film which is being taken up or rolled becomes a factor of vital
importance and essential to the practically successful production of a smoothly and
evenly rolled multiply tube devoid of air-bubbles between its plies or layers, it
being observed that if during the process of forming the tube, one or more air-
bubbles is or are caused or allowed to form at any point or points between the plies
or layers, the tube will be imperfect. By said mode however, the outer ply or layer
of film can be rolled up smoothly, evenly compactly and directly upon the next
inner ply or layer of film or air can be effectively excluded from between them,
even should any inequalities in thickness exist in the film from which the tube is
formed, it being a fact that such inequalities will exist in such film, although it can
be made more perfect than "sheet rubber." A feature of further and much import-
ance, particularly during the formation of the second and any succeeding plies or
layers is the adaptability of the elastic yielding surface to permit the mandrel and
intervening strata of film to be depressed into said surface which under such
pressure yields along the entire length of the mandrel and conforms to the same.
In this way, the rubber film is subjected to an increased area of elastic bearing and
resisting surface which will roll up or rise in advance of the forwardly moving
mandrel. During such operation however, the thin rubber film wilt wrinkle or
pucker in advance of the mandrel, but by using an independent mandrel and
manually rolling the same along the sheet of film, the operators can at any desired
moment give the mandrel a short bodily back movement, thereby straightening
out the sheet of film so as to remove not only the wrinkles or puckers formed as a
result cf. the rolling process, but also such wrinkles as may exist as a result of
laying the sheet upon the bed, it being observed that all such puckers or wrinkles
must be removed in order to form a perfect air-tube.
After the multiply air-tube has been formed as aforesaid, it is vulcanized,
whereby the plies or layers are united as one sheet so as to form a light, seamless,
perfect, durable and highly flexible inflatable tire-tube peculiarly adapted for service
in a pneumatic tire, in which it is desired to use the inflatable tube not as an elastic
structure or cushion but simply to prevent the leakage of a body of air which of
itself forms the elastic cushion.
In the accompanying drawings,
Figure 1 is a plan view of an adhesive sheet of unvulcanized rubber film, laid
upon an elastic yielding bed-surface with the mandrel placed upon said bed adjacent
to the sheet of film, preparatory to the operation of rolling the same into a multiply
inflatable tire-tube.
Figure 2 is a cross-section through the same, on an enlarged scale with the
mandrel slightly advanced, so as to illustrate the mandrel as having taken up a
portion of the thin adhesive sheet of film preparatory to rolling the same into
tubular form.
Figure 3 is a like view illustrating the formation of the first ply or layer.
Figure 4 is a like view illustrating the formation of a couple of plies about the
mandrel.
Figure 5 is a like view showing a three-ply tube formed upon the mandrel.
Figure 6 is a longitudinal section through a portion of the tube formed with
three-plies of film.
Figure 7 is a view similar to Fig. 1 but showing the mandrel arranged obliquely
to the length of the sheet of film.
Figure 8 shows the air-tube in longitudinal section, (on the scale of Fig. 6)
with its middle portion broken away for convenience of illustration. This view

page_text: indicates a way in which the ends of the tube can be closed after it has been formed
upon and removed from the mandrel.
The sheet A of film is formed by rolling out unvulcanized rubber preferably
of the kind known as pure rubber, between suitable rolls. A rubber film com-
posed of some suitable rubber compound might be used, it being observed however,
that what is known as pure rubber or substantially pure rubber is regarded as
the best, and that the mode herein employed of manipulating the film permits
the use of pure or comparatively pure material. Also that the more the pure
rubber is compounded with other material the heavier it becomes, and as lightness
is an important feature, pure rubber, that is to say, rubber nixed with sulphur is
preferably used. These tubes can be made with little or no loss, and in thus
making them, a film of about one sixty-fourth of an inch in thickness is desirably
employed. A thinner or a slightly thicker film could be used and hence the invention
is not confined to a determinate thickness of film, it being however, distinctly under-
stood that the term film as herein employed has a distinctive meaning and distinctive
characteristics, in contradistinction to the thin rubber sheets, heretofore employed
in making air-tubes for pneumatic tires.
The elastic yielding surface is formed by a bed or cushion table B of any suitable
elastic material, it being expressly.understood that the invention is not limited to
any particular kind of elastic substance or material, and that any material or
substance adapted to afford an elastic yielding surface, or surface having a function
and adapted for the purpose of the invention can be used.
In order to form a multiply tube, a sheet of the aforesaid sheet of film is laid
upon the yielding bed, the length of such sheet being proportioned to the required
length of the air-tube to be made, and its width being proportioned to the number
of proposed plies. The independent mandrel is then taken and laid upon the bed
alongside one edge of the sheet of film, and is then manually rolled over the sheet
of film by several workmen standing alongside the bed which is understood to be
suitably elevated for such purpose.
The manner in which the mandrel C first picks up the film A, is illustrated in
Fig. 2, the formation of the first ply or layer a is shown in Fig. 3, and the formation
of a second ply or layer a¹ is shown in Fig. 4 wherein the unrolled portion of the
elastic sheet A is understood to be sufficient for the formation of a third ply
or layer a², represented in Figs. 5, 6, and 8.
-
The tube may be formed of two or more plies, but in practice a three-ply tube A¹
can be produced with excellent results. This will be apparent from the following:-
Where the film is for example, one sixty-fourth of an inch thick, and is rolled
upon itself to form a three piy tube, the tube will be three sixty-fourths of an inch
thick, and at the same time will be composed of three plies or layers united
together as one. Should any imperfections therefore, have primarily existed in
the film, it is not likely that three points of imperfection in the material forming
the three plies will be brought into register with one another. It will also be
seen that a light and extremely perfect tube is produced by reason of the use of a
thin film which can be more perfectly and readily wrapped upon itself to the
exclusion of air-bubbles from between the plies. If the film should be thickened,
for making a three ply tube, a heavier tube, proportional to the increase in thickness
of the film would be produced, and if it is desired to make a tube of about the
thickness of a tube composed of three plies each say one sixty-fourth of an inch
thick, and use but two plies, the production of such will obviously entail the
disadvantage of using a heavier film. Figs. 2, 3 and 4 also illustrate the way in
which the elastic yielding surface is depressed during the advancement of the
mandrel, the depression shown at b being understood to extend the length of the
mandrel. This depression of the elastic yielding surface by and during the travel
of the mandrel is of obvious advantage not only during the formation of the
succeeding ply or plies, since it is necessary to the production of a perfect article
that no air-bubbles sball be left between the plies or layers. By depressing the
mandrel during the process of rolling it along the sheet of film, the plies will

page_text: be laid evenly and smoothly and the air will be excluded so effectively from
between the plies as to ensure their formation without intervening air-bubbles.
This method of subjecting the thin sheet of film to an elastic yielding pressure
during the process of rolling it to form a multiply tube and of manually handling
the mandrel also permits the rolling process to be performed with ease and
rapidity, and permits the rapid and economical production of a perfect article, it
being observed that during such operation the manipulation of the mandrel is
subject to the judgment of the workmen whose further duty it is to see that no
wrinkles are left in the film when rolled.
In practice, a set of operators (usually three) should stand constantly alongside a 1
long table having its top provided with a yielding bed. The long narrow sheet of
film laid upon the bed in front of these operators is thin, sticky and filmy, and to
spread it out without wrinkles would involve much care, time and labor and in fact
would be almost impracticable. The sheet of film also invariably puckers or
wrinkles in advance of the mandrel, during the operation of rolling it into tube-
forms. These wrinkles must be taken out, and this can be done by the operators
while rolling up the film. To such end, while rolling up the film, the operators
during each operation can give the mandrel a short quick back movement which
draws back upon the film and removes the wrinkles. As soon as a tube is rolled,
it is taken away and another sheet of film and mandrel supplied the operators. In .
practice, three operators can, and do roll up from seventeen hundred to two
thousand of such tubes a day.
After thus forming the tube, it is removed from the mandrel by first forcing an air
blast together with pulverized soap-stone or the like between the tube and mandrel and
then withdraw the latter, and by using an independent mandrel, the mandrels can
be quickly transferred from the cushion table to the workmen who can remove the
tubes therefrom. In order to close the ends of the tube so that it can be used in a
pneumatic tire, the end portions of the tube can be flattened as a³ in Fig. 8, and
the tube can then be vulcanized aud by so doing, the plies or layers will be united
as one. The tube can also be vulcanized in a generally flattened condition for
certain kinds of tires.
The thin sheet of film A could be rolled spirally or obliquely about a mandrel so
as to form in effect a multiply tube, and to such end the mandrel can at the start
be arranged obliquely to the length of the sheet of film as in Fig. 7, it being
understood that in such case the elastic yielding bed or surface is necessary for
the purposes herein before described, and that the ends of the tube must be cut
off after its removal from the mandrel. In all other respects, the operation is
substantially the same as that herein before described.
While the mandrel which consists of a straight cylindric rod proportioned with
reference to the required size of tube may be of any suitable material, a matter of
further improvement consists in the mandrel composed of a rod capable of elastic
spring or bending action, so that during the process of rolling up the film the
mandrel can be sprung or bent back when such is found desirable as a means för
straightening out the sheet of film so as to remove wrinkles or puckers.
As a matter of further improvement, a mandrel having a wooden surface is
provided. This is highly advantageous in both of the within described ways of
rolling up the film, since it takes up and handles the same much better than can be
attained by employing a metallic mandrel. As a simple and desirable arrangement
the mandrel is preferably made of some springy wood, which combines the
advantages of a mandrel capable of elastic bending action and having a wooden
surface.
It is obviously within the range of possibility to longitudinally divide the sheet
of film so as to provide separate pieces or layers of film, and to then roll the same
either simultaneously or separately about the mandrel so as to form a multiply
composite tube and that these layers can be smoothly and evenly rolled to the
exclusion of air-bubbles, by compressing them between the mandrel and an elastic
yielding resistance as aforesaid. And while therefore the preferred mode of rolling

page_text: up a single piece of rubber film is specifically claimed, both of said ways are also
broadly claimed so as to include forming a multiply tube by rolling up rubber film
either in one piece of sufficient width, and also by rolling up a plurality of pieces
which for example can be successively rolled and distributed so as to cover up
the seams.
No limitation is placed upon the particular material for forming the elastic
yielding bed, it being observed that a bed comprising hair felt &¹ covered with cloth
or canvas, is highly satisfactory.
For the purpose of Claim 1, the invention covered thereby is not limited to
manually rolling the mandrel upon the yielding bed surface or cushion table,
although in view of the advantages and better results attained by the manual
process over what could be done by the mandreling machine, such manual operation
is regarded as a matter involving distinctive improvement and invention and as
preferable.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:-
1. The within described process of preparing inflatable air-tubes for pneumatic
tires consisting essentially in the following steps, to wit:-forming unvulcanized
rubber into a thin film; placing said film upon a cushion table; forming said film
into a multiply tube having its plies in direct contact one with another by rolling
the film, thus arranged, upon a mandrel, and during such operation subjecting the
film or plies of film to compression between the cushion table and the mandrel;
and vulcanizing the multiply tube thus formed so as to unite, the plies of film and
adapt the tube for service in a pneumatic tire-sheath.
2. The within described process of preparing inflatable air-tubes for pneumatic
tires consisting essentially in the following steps, to wit:-forming unvulcanized
rubber into a thin film, placing a sheet of said film upon a cushion table; forming
said film into a multiply tube having its plies in direct contact one with another by
manually rolling a free and independent mandrel upon the film thus arranged, and
during such operation subjecting the film or plies of film to compression between
the cushion table and the mandrel at the will of the operator; and vulcanizing
the multiply tube thus formed so as to unite the plies of film and adapt it for
service in a pneumatic tire-sheath.
3. The within described process of manufacturing inflatable air-tubes for
pneumatic tires consisting in forming unvulcanized rubber into a thin film; spreading
a sheet of said film upon a cushion table; forming said sheet of film into a multiply
tube having its plies in direct contact one with another by rolling it about a
mandrel subjecting the film while being thus rolled to compression between the
mandrel and the yielding cushion table; removing wrinkles or gathers in the sheet
of film during said operation by stretching the portion of the sheet in advance of
the mandreland vulcanizing the multiply tube thus formed so as to unite the plies
and adapt it for service in a pneumatic tire-sheath.
4. The within described process of preparing inflatable air-tubes for pneumatic
tires consisting in spreading a sheet of thin unvulcanized rubber film upon a cushion
table; forming said sheet of film into a multiply tube having its plies in direct
contact with one another by manually rolling an independent mandrel over the film
thus arranged; subjecting the film while being thus rolled to compression between
the mandrel and the cushion table and during the formation of the tube upon the
mandrel giving the latter a temporary and limited back movement for the purpose
of stretching the film in advance of the mandrel; and vulcanizing the multiply
tube thus formed so as to unite the plies and adapt it for service in a pneumatio
tire-sheath.
5. The within described process of preparing inflatable air-tubes for pneumatic
tires consisting in forming unvulcanized rubber into a thin film; spreading such
film upon a cushion table; forming said film into a multiply tube having its plies

page_text: in direct contact one with another by rolling a free and independent mandrel over
the film thus arranged upon the cushion table and during such operation subjecting
the film to compression between the yielding cushion table and the mandrel;
removing the multiply tube thus formed from the mandrel by forcing air carrying
powdered soap-stone or the like in between the mandrel and tube so as to permit
the mandrel to be drawn from the tube; and vulcanizing said tube after its
removal from the mandrel.
6. An apparatus for preparing inflatable air-tubes for pneumatic tires from
unvulcanized rubber film consisting in a cushion table adapted to receive a sheet
of unvulcanized rubber film from which the said tube is to be made, and an inde-
pendent flexible mandrel upon which the film can be rolled to form a multiply
air-tube, substantially as and for the purpose described.
7. An apparatus for preparing inflatable air-tubes for pneumatic tires from
unvulcanized rubber film consisting in a cushion table adapted to receive a sheet of
unvulcanized rubber film from which the said tube is to be made and an independent
flexible wooden mandrel upon which the film can be rolled to form a multiply
air-tube, substantially as and for the purpose described.
8. As an improved article of manufacture, a multiply air-tube for pneumatic tires
characterized by the within described formation, and composed of a plurality of
plies of rubber film directly united to each other by compression and vulcanization,
substantially as described."
Dated this 5th day of January 1895
A. E. ALEXANDER,
19, Southampton Buildings, Chancery Lane, London, W.C.,
Chartered Patent Agent.