Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present invention relates to a pressurized
heating apparatus for vulca~izing parts o~ vulcanizable
rubber tire in contact with each other by means of a heat-
bearing fluid in order to cause the parts to adhere firmly
to each other. This apparatus may be used for retreading
or repairing a tire.
In order that the bond between the parts to be
adhered to each other will be fir~r it is absolutely neces-
sary to prevent heat~bearin~ fluid from penetrating between
these parts. The most common means used to prevent such
penetration conslsts of a sheathing, or flexible membrane
or film, generally of elastomer, which covers at least the
region of the interface of the parts of the tire which are
applied against each other.
A tire retreading apparatus in which such a mem-
brane is provided is described in U.S. patent No. 4,111~732.
In that apparatus, the heating is effected by a liquid, which
involves a system of pipes, connections, valves, etc., which
is relatively complicated. Another drawback of this known
apparatus is that the membrane or membranes used apply them-
selves not only against the sides of the tire, in the region
of the interface of the parts thereof which are to be connec-
ted together by vulcanization, but also against the tread
of the tire over the entire width of the tread. In the
case of a premolded tread with grooves, the membrane which
surrounds the tread cannot reach the bottom of these grooves
so that the pressure is not uniform over the entire width
of the tread, which leads to defects in adherence.
A retreading method and appa atus which operate
without the use of a membrane are, to be sure, described in
West German Unexamined Patent Application No. 2,3a3,282.
This method and apparatus, however, have the drawback, on
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the one hand, that there is a danger that the pressurized
heating fluid whlch surrounds the tire may come between the
parts thereof which are to be united to each other by vulca-
nization, while, on the other hand, it is impossible to ef-
fect the vulcanization of a repair under good conditions,
particularly in the region of the side~walls of the tire.
From French patent No~ 2.184,515 there is also
known a process and apparatus for the vulcanization of tires
which makes use of hot air agitated within the tire by a
fan arranged on the axis of rotation of the tire. One
drawback of this known apparatus is that it can receive
only tires which are all of the same dimensions, because it
~s formed of rigid mold shells. Furthermore, the fact that
the heated air is in contact only with the inner wall of
the tire leads to longer sejourn times in the apparatus
than when heating is provided also against the outer wall
of the tire.
The object of the present invention is therefore
in ordre to cause parts of a vulcanizable rubber tire to
adhere firmly to each other, to provide a pressurized heat-
ing apparatus which is free oE all the drawbacks described
above.
In ordre to achieve this object, the invention
provides a pressurized heating apparatus having the follow-
ing features:
(a) a cylindrical tank formed of a circular back
and of a circular front cover articulated to the back is
supported on a frame;
(b) a cylindrlcal hub forming a mounting rim for
the tire to be heated is lntegral with the back oE the tank,
concentric with the back and is provided in its periphery
with fluid-circulation openings,
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(c) between the outer periphery of the hub and
the inner periphery of the back of the tank there extends
a first flexible annular membrane of crown shape, spaced
from the back of the tank and, on the whole, parallel to
the back;
(d).a second flexible annular membrane of crown
shape extends, spaced axially from the first membrane and
from the inner face of the cover and, on the whole, parallel
to the cover, between the periphery of the cover and an
annular rib which is integral with the inner face of the
cover, is coaxial with the hub and forms a rim flange, the
space between the two membranes defining in axial direction
a receiving enclosure for receiving the tire to be heated;
(e) an annular space contained between the back
of the tank, the first membrane a~d the hub, and an annular
space contained between the cover, the second membrane and
the annular rib forming a rim flange, are connected to a
source of pressurized fluid;
(f) a fan and a first electrical heating resistor
are arranged in the hub coaxially with the hub;
(g) a fan is arranged at the top of the tank
between the back and the cover of the tank, midway between
the two membranes;
(h) a second electrical heating resistor is
arranged.along the periphery of the tank within the tank
between the two membranes î
(i) when a tire is in place on the hub within the
receiving enclosure, the tire subdi~ides the receiving en-
closure into an annular compartment contained between the
crown of the tire, the two fle~ible membranes and the peri-
phery of the tank, and into a central compartment located
radially inward of the annularco~partment and defined by
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the.inside of the tire and the hub, each of these two com~
partments being connected independently of each other to
a source of pressuri~ed fluid.
It is advantageous furt~ermore to provide a centxal
control for the fans and electrical heating resistors con~
nected to thermal detectors arranged within the tank.
Other details and advantages of the apparatus of
the invention will become evident from the description of
an illustrative embodiment given below with reference to
the accompanying drawing in which~
Fig. 1 is a view in side elevation, in radial sec-
tion, of a pressurized heati~ apparatus in accordance with
the invention within which a tire to be heated is contained,
and
Fig. 2 is a view on a smaller scale of the inside
of the apparatus along the median plane XX' of Fig. 1,
without the tire.
A cylindrical tank 1 formed of a circular back 2
and of a circular front cover 3 articulated to the back 2
~0 is sùpported on a frame A shown in Fig. 2.
In order to support the tire P to be heated, the
back 2 has integral with it a cy~lndrical hub 4 whose axis
5, which is also the axis of the tank 1 as a whole, is
horlzontal. Coaxlally with the huh 4, the inner face 3' of
the cover 3 has integral with ~ an annular rib 3" whose
inside diameter corresponds substantially to the outside
diameter of the hub 4. The annular rib 3" forms a rim
flange. In order to receive tires whose beads Pi" have a
diameter greater than that of the hub 4, interposed rings
(not shown) may be arranged between the beads P"' and the
hub 4.
Between the inner periphery 2' of the back 2 and
the outer periphery of the hub 4 there extends a first
flexible annular membrane 6 of crown shape which is parallel,
on the whole, to the back 2 and spaced from the back 2,
while between the perip~ery 31 of the cover 3 and the annu-
lar rib 3" there extends a second flexible annular membrane
6' of crown shape which is parallel, on the whole, to the
cover 3 and spaced from the inner face 3' of the cover 3.
The membranes 6 and 6' are opposi~e each other and are at
a distance apart which corresponds approximately to the
largest a~ial width o~ the tire P. The space between these
two membranes constitutes a receiving enclosure for the
receiving of the tire P.
The hub 4 is provided in its periphery with fluid-
circulation openings 4' which place the inside of the tire
P .in communication with the enclosure 4" of the hub 4 de-
fined by the periphery of the hub 4 and by two partitions
? and 7' parallel to the median plane X-X' of the tan]c 1.
Within this enclosure 4" there are arranged a fan 8 and a
first electrical heating reslstor 9 which are ~coaxial with
the hub 4.
An annular space 10 contained between the first
membrane 6, the back 2 of the tank 1, and the hub 4, as well
as an annular sp~ce 10' containe~ between the second mem-
brane 6', the cover 3, and the annuIar rib 3" / are connected
- to a source of pressurized flui~ by connecting nipples lOA
and lOB, respectively, in order to apply the membranes 6,6'
against the tire P. When a tire P is in place on the hub
4 within the receiving enclosure, its crown PS subdivides
the receiving enclosure into two compartments 11 and 12.
The annular co~mpa~t~en,t-llis contained between the crown
Psr the two flexiblé membranes 6,6' and the periphery 1' of
the tank 1. The c,entral compartment 12 is loca-ted radially
inward of the annular compartment 11, is defined by the in-
side of the tire P and the hub 4 and communicates with the
enclosure 4" of the hub 4. Each of these two compartments
11 and 12 is connected independen~;ly of each other to a
source of pressurized fluid by connecting nipples llA and
12A, respectively.
At the top of the tank 1 in the annular compartment
11 a fan 13 is installed radially inward of a second elec-
trical heating resistor 14 which, in this example, extends
all around the periphery 1' of the tank 1.
In order that the heating temperature not be much
higher in the upper portion of the annular compartment 11
than in the lower portion thereof, a rigid annular heat
screen 15, interposed between the second electrical heating
resistor 14 and the crown P5 of the tire P, has perforations
15' the number and/or size of which increase from the upper
portion (upper half) to the lowe~ portion (lower half) of
the annular compartment 11. The heat screen 15 is, OI
course, closer to the second heat~ng resistor 14 than to
the hub 4. Furthermore, the fans 8 and 13 and/or the elec-
trical heating resistors 9 and 14 are connected to a thermo-
static regulation box C which controls these fans and/or
these resistors as a function of the temperatures recorded
at the top and bottom of the annulax compartment 11 and in
the central compartment 12 by thermal detectors (not shown)
which are connected to the inlet E of this box C.
In order that the flexible membranes 6,6' will
apply themselves properly against the carcass P" and the
edges of the tread P' of the tire P under the effect of the
pressurized fluid introduced into the annular spaces 10,10'
it is preferable that the membranes 6,6' be as thin as
possible in the portion thereof inteded to come into contact
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with the zone along which the edges of the tread P' of the
tire P adhere to the carcass P" thereof. On the other
hand, in the region of the beads P"~ of the tire P, it is
preferable that these membranes 6,6' be thicker, as shown
in Fig. 1, in order to withstand better the various stresses.
Furthermore, in order that these two membranes 6,6' of
crown shape have the possibility of snugly fitting the outer
shape of the carcass P~ of the tire P, their developed
radial length between their outer periphery and their inner
periphery is, on the one hand, greater than the distance D
between the radius R oE their zone of outer peripheral at-
tachment and the radius r of their zone of inner peripheral
attachment. On the other hand, a drainage system, known
per se (not shown), which is connected to a source of
vacuum can be pro~ided between the membranes and the car-
cass or sidewalls P" of the tire P in the surface defined
by the inner periphery and the outer periphery of the tire
P up to the limit of the edges of the tread P' forming a
sealing zone.
The tire P installed on the hub 4 between the two
membranes 6,6' receives a hot fluid, e.g., a gas such as
air, on the one hand, against the outer periphery of its
tread P' coming from the second electrical heating resistor
14 and the fan 13 and, on the other hand, against the inner
perlphery of the carcass of sidewall P" and the crown PS
coming from the first electrical heating resistor 9 and the
fan 8, while the annular spaces 10, 10'-and the annular com-
partment 11 are maintained under a pneumatic pressure which
is substantially equal to that which prevails in the centràl
compartment 12.
When the heating of the tire P is finishéd,
atmospheric pressure is reestablished throughout the entire
tank 1. The cover 3, to which the membrane 6' ls fastened,
can then be opened. The tire P can then be removed from
the hub 4 and the ne~t tire mounted on the hub 4~
