Improvements in the Manufacture of Pneumatic Tyres, and in Apparatus therefor.
Year: 1896

page_text: Date of Application, 19:h Nov., 1896-Accepted, 27th Feb., 1897
COMPLETE SPECIFICATION.
[Communicated from abroad by FRED WILLIAM MORGAN, of 339 West Lake
Street, Chicago, Illinois, United States of America, Rubber Manufacturer.]
Improvements in the Manufacture of Pneumatic Tyres, and in
Apparatus therefor.
I, DAVID YOUNG, Patent Agent, of the Firm of D. Young & Co., of
11 & 12 Southampton Buildings, London, W.C. do hereby declare the nature of
this invention and in what manner the same is to le performed, to be particularly
described and ascertained in and by the following statement:-
This invention relates to the manufacture of pneumatic tires, involving as a
maiter of general construction, a seamless, tubular shoath or casing, and an inner
air-tube which can be removed and replaced through a short slit in the base or
seating portion of the sheath.
The object of the invention, is mainly, to produce a flexible, durable sheath, in a
rapid and economical way.
In carrying the invention into effect, a strip of fabric suitably "frictioned "
with unvulcanized rubber, is formed into an endless band by lapping together its
euds. This endless band will normally coincide with the circumference of a circle
which is somewhat less than the circumference of an annular, separable mandrel
upon which the sheath is to be moulded and vulcanized. The endless band is then
placed upon the annular mandrel, and in so doing, the band will be uniformly
stretched along its longitudinal middle portion, and remain in such condition
throughout the remaining portion of the process of forming, moulding and vulcanizing
the sheath. The unstretched n.arginal portions of the band are then smoothed
down upon the mandrel, and a strip of unvulcanized rubber is then placed upon the
band, by rolling the mandrel, thus covered with fabric, along the strip of rubber.
The whole is then placed in a divided, metal mould, and subjected to heavy
hydraulic pressure and vulcanization, after which, it is removed from the mould,
and the sheath is removed from the mandrel, by cutting a short slit in the sheath
and causing the mandrel to part from the latter by way of such slit. The pre-
liminary treatment of the fabric, whereby it is placed and hold on the mandrel
under longitudinal tension along its longitudinal middle portion, has direct reference
to the moulding of the sheath in a metal mould under hydraulic pressure, the result
being that in the completed sheath, the fabric along the tread portion thereof will
be smooth and devoid of a longitudinal wrinkle or pucker, which will occur if the
fabric is not thus placed under longitudinal tension, and which if present, will
render the tire less durable, for the reason, that when the tire is inflated, the
internal pressure will tend to draw out the wrinkle and in so doing stretch and
weaken the rubber along the middle line of the tread. The mandrel is desirably
of solid metal, preferably steel, whereby during the vulcanization of the sheath, the
solid metal mandrel which at the start is cool, will conduct the heat from the fabric
and thereby protect the latter.
In the accompanying drawings,-
Figure 1 illustrates a strip of fabric from which the endless band can be made.
Figure 2 illustrates nient war of forming the endless hand uno colle

page_text: which are gauged with reference to the proposed length of normal circumference of
the endless hand..
Figure 3 shows the band, unstretched, and in circular form.
Figure 4 is a side elevation of a holder upon which the mandrel is placed,
preparatory to placing the endless band upon the latter.
Figure 5 is a top, plan view of Fig. 4.
Figure 6 is a view similar to Fig. 4, showing the baud stretched upon the
mandrel.
Figure 7 is a section taken centrally through Fig. 6 on a vertical plane.
Figure 8 shows in side elevation, the mandrel with the band of fabric thereon,
preparatory to smoothing down the unstretched edge portions of the fabric.
Figure 9 is a section taken transversely through Fig. 8, on a larger scale.
Figure 10 is a view similar to Fig. 8 showing the fabric smoothed down
upon the mandrel.
Figure 11 illustrates the mandrel thus covered with fabric, in the act of
being rolled along a strip of rubber, and shows in cross section a guide for the
mandrel.
Figure 12 is a plan of the strip of rubber, in part broken away for convenience
of illustration.
Figure 13 is a side view of the guide, with the fabric of rubber; the guide being
in part broken away for convenience of illustration.
Figure 14 is a plan of one of the halves of the mould, with the mandrel covered
with fabric and rubber, in place therein.
Figure 15 is a section taken transversely through the complete mould, with the
imandrel covered with fabric and rubber therein.
Figure 16 shows in elevation, the hydraulic, vulcanizing press, with the mould
theroin.
Figure 17 shows a way in which the mandrel can be opened so as to permit the
sheath to be removed therefrom).
Figure 18 illustrates the removal of the sheath from the mandrel.
Figure 19 illustrates the completed tire.
Figures 20 and 21, are to illustrate the way in which a defect will occur in the
sheath, if the band be not stretched upon the mandrel, Figure 20 being a section
through the mould and mandrel, with rubber and non-stretched fabric upon the
mandrel, and Figure 21 being a section through the inflated tire, with the wrinkled
fabric of Figure 20 drawn smooth, thereby drawing out the wrinkles aud at the
same time stretching and weakening the rubber.
The strip A, shown in Fig. 1, can be of one or more layers of suitably
"frictioned "fabric, (that is to say, fabric treated with unvulcanized rubber by
passing the fabric and rubber between rolls), a preferred arrangement being to
ferm such strip of a layer a of frictioned duck, and a layer a' of frictioned
drilling. Each layer can of course be of one piece, but as the strip is cut on the
bins, the width of fabric, as commonly found on the market, does not admit of a
single strip of suitable length being cut therefrom. Owing however, to the
sticky, rubber upon the fabric, the ends of the pieces will suitably and effectively
adhere, the oue to the other, when they aro lapped and pressed together. The
narrower piece or layer a', when thus employed, should terminate short of one
end of the layer a, and extend beyond the opposite end of the latter, whoreby
the laps of the layer which form the endless band will be at different points
along the latter as indicated in Fig. 2 in which the strip is shown as formed
into an endless band. The proper size of the band can be determined in various
ways, as for example, it can be formed upon a druin, but as a more convenient
way, it is formed by passing the strip over a couple of rolls B which are arranged
upon a support C, and so sized and set apart, that when the endless band D which
has been formed thereon from the strip A of Fig. 1, is brought while unstretched,
into the circular form of Fig. 3, it will have a circumference which is somewhat
less than the circunference of the annular mandrel E.

page_text: The ends of the strip of fabric can be conveniently lapped together upon one
of the rolls B, so as to form the endless band, and whilo they could be subsequently
stitched, it will be sufficient to simply rely upon their tendency to adhere together
by reasou of the sticky rubber with which they are coated.
The annular mandrel E is an annular metal rod-preferably of steel-which is
solid and provided with a removable section e held in place by tongue and groove.
joints. This mandrel is temporarily placed upon a holder, such as a conical-
frustum F, and the endless band is then stretched upon the mandrel, whereby
while the longitudinal edge portions of the endless band remain unstretched,.
the longitudinal middle portion of the band will be under longitudinal stretch
upon the mandrel, as indicated in Figs. 6, 7, 8, and 9. The inandrel is then
removed from the holder F, and the edge portions of the fabrio are smoothed
down upon the mandrel, as in Fig. 10. The mandrel is then placed in a.
guide G, comprising an oblong bed g baving a straight, longitudinally arranged
channel g', and an overhead guide-way formed by the space between a pair of
parallel and horizontally arranged rails g, g' which are supported over the bed by
suitable standards 9. A strip H of unvulcanized rubber is laid upon the bed g of
this guide, and arranged over the groove g' therein, so that the mandrel, while
rolling along such strip, will depress the same in the channel, as in Fig. 11. The
mandrol extends up between the guide-raile g³, g², and hence it will be guided, both
by said rails, and by reason of the channel g into which it will depress the rubber'
strip. As the mandrel is rolled along the rubber strip it will pick up the same, as
shown in Fig. 13, which illustrates a portion of the rubber strip thus picked up by
the inandrel. The annular mandrel thus covered with fabric and rubber, is then-
placed in a two-part metal mould I, each half of which has an annular concave
groove, so that when the two parts of the mould are together, as in Fig. 15, the
mandrel with its covering will be confined within an aunular bore which is circular
in cross-section. The mould is then placed in a hydraulic vulcanizing press, where
the material upon the mandrel is subjected to hydraulic pressure and vulcanization.
The hydraulic press, which is illustrated in Fig. 16, is constructed with two steam-
chambers K, and K', the upper chamber K being fixed, and the lower chamber K'.
being arranged for vertical movement upon the guide and supporting rods L.
These two chambers are conveniently supplied with steam from a supply pipe M.
having a coil m, which allows the lower arm m of the pipe to move with the lower
movable steam-chamber. The lower steam chamber is rigid with and thereby in:
effect forms the upper end of a plunger N, which latter works in a pot or
cylinder O, the latter being supplied with water under pressure, from a supply
pipe P.
After vulcanizing, the mould is removed from the press, and the mandrel with
the vulcanized sheath thereon is removed from the mould, and a short slit is made
through the sheath at a point opposite the removable section of the mandrel. The
mandrel with the sheath thereon is then placed upon a bench Q, Fig. 17, having a
stopy thereon, and a hand lever R is inserted in a space between the end of the
bench and the mandrel, as in Fig. 17 and by then operating the lever in a direction
to draw the sheath covered mandrel against the stop g, the mandrel will spring
open to an extent to permit its removable section to be withdrawn through the slit
in the sheath. One end of the mandrel is then placed in a clamp S, which is in
turn tightened up in a vice T, and the sheath is then stripped from the mandrel as
illustrated in Fig. 18. After such operation, an air-tube can be introduced within
the sheath, by way of the short slit h in the latter, and the slit can then be laced
up, so as to form the completed tire U, shown in Fig. 19.
The importance of forming the strip of fabric into an endless band, which is
stretched on the mandrel, as hereinbefore set forth, is further illustrated by
Figs. 20 and 21, in which the fabric is understood to have been placed upon the
maudrel without stretch and consequent longitudinal tension. As a result, the
fabric, not under longitudinal tension will gather or pucker so as to form an
annular wrinkle V along the middle outer circumferential line of the inandrel,.

page_text: as well as along the middle inner circumferential line thereof, it being
observed that such wrinkles are opposite the line of separation between the two
parts i,, of the mould, and that the portion of the rubber which is formed between
said parts of the mould, and which thereby forms a fin A, is pared off from the
sheath after moulding and vulcanizatiou.
If now the sheath having wrinkles as in Fig. 20, is completed, and supplied with
an air-tube, and the latter inflated, the lateral tension upon the fabric will draw
out the wrinkles as in Fig. 21, and at the same time will stretch the rubber along
lines opposite the lines along which the wrinkles existed. This will reduce the
rubber in thickness as at A, and stretch and weaken it, and in time, the sheath
will be extremely liable to crack along its middle tread line, it being observed that
as the sheath is cemented upon the wheel rim W, and as no wear occurs upon its
base, the weakened portion along its middle base line will not affect the wearing
properties of the tire.
Having now particularly described and ascertained the nature of said inven-
tion, and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is :-
1. The within described improvement in the manufacture of pneumatic tires,
consisting essentially in the following steps, to wit:-forming a strip of one or
more layers of frictioned fabric; forming this strip into an endless band; placing
this endless band upon an annular separable mandrel having a greater circumference
than the normal circumference of said band, thereby causing the longitudinal
middle portion of the band to stretch upon the circumference of the maudrel and
remain thereon under longitudinal tension; Binoothing the remaining portion of
the band down upon the mandrel; applying a strip of rubber upon the fabric;
moulding and vulcanizing the material thus arranged upon the mandrel in a
sectional mould, under pressure, thereby forming a scamless, tubular structure, and
then removing the sheath from the mandrel.
2. Arranging upon an annular solid metal mandrel having a removable section,
an annular band of fabric under longitudinal tension along its middle longitudinal
portion which lies upon the outer circumference of the mandrel; arranging a strip
of rubber upou the fabric; vulcanizing the structure thus formed in a mould
subject to hydraulic pressure in a combined hydraulic press and vulcanizing
apparatus and subsequently opening the vulcanized structure to a limited extent
and removing it from the mandrel.
3. Apparatus such as set forth comprising ineans for gauging the size of the
endless band of fabric; a device for holding the mandrel while placing the endless
band thereon; a device for guiding the mandrel while rolling the same along the
strip of rubber; and a combined hydraulic press and vulcanizer and separable
metal mould adapted to be placed therein.
Dated the 19th day of November 1896
D. YOUNG & Co.,
11 & 12 Southampton Buildings, London, W.C.,
Agents for the Applicant.