Process and apparatus for manufacturing radial tires

A process is provided for manufacturing radial tires for a motor vehicle having a radial carcass, a reinforcing structure with at least two layers of criss-crossed symmetrically arranged metallic cords forming a belt, and a tread. The process involves a series of steps which comprise: building up a carcass in a cylindrical configuration on a first expandable building drum and shaping the carcass into a toroidal configuration. A reinforcing belt is also formed by winding two layers of metallic cords on an auxiliary expandable drum with a diameter equal to the external diameter of the toroidal shaped carcass. The belt is maintained in slidable contact on the drum and shaped toroidally by expanding the auxiliary drum. The belt is then removed from the auxiliary drum and transferred with a tread band to the carcass on the first drum. The carcass is toroidal shaped again to assemble the carcass and belt. The assembly is vulcanized under pressure in a mold.

This invention relates to a process for manufacturing radial tires and to 
an apparatus for practicing the process. The radial tires comprise, from 
inside to outside, a carcass having one or more plies wherein the cords 
lie substantially in meridian planes; a ring-shaped reinforcing structure 
formed by at least two layers of metallic cords criss-crossed one with the 
other and oriented symmetrically with respect to the longitudinal 
direction of the tire; and a tread. 
Generally speaking, these tires have been manufactured in accordance with 
prior art processes by disposing the carcass plies in a cylindrical 
configuration on a special expandable building drum, then bringing this 
first configuration of the carcass to a toroidal configuration, and 
finally, disposing onto this carcass the reinforcing structure and the 
tread band. 
In the case of radial tires that have particular characteristics such as, 
for example, more comfortable and better handling, there exist other 
`known` manufacturing processes as well. 
In general, these processes consist in applying the annular reinforcing 
structure on the toroidal-shaped carcass that has already been built on a 
building drum through an expandable membrane, and subsequently, in taking 
the carcass, with its associated reinforcing structure, and in the absence 
of the tread, to a second toroidal shape by means of a further expansion 
of the drum membrane. 
By this process owing to the fact that the cords are not obstructed in 
their movement by a tread band, a more uniform disposition of the metallic 
cords is achieved and, moreover, a state of tension is obtained in the 
cords that increases the tire's resistance against lateral and torsional 
stresses. 
In particular, the various assembling operations, the centering and the 
reciprocal aligning of the various tire component parts onto the building 
drum, all require the use of a great number of devices around the drum 
itself. For example, the so-called `bells` or equivalent supports are used 
for positioning the annular reinforcing structure onto the carcass, after 
the first toroidal shaping, and also for positioning the tread, after the 
second toroidal shaping of the carcass. 
Consequently, all these manufacturing steps and the apparatus used in 
practicing them are very complex. Moreover, the various inspection, 
checking-up and other manual operations required are to a certain extent, 
obstructed by the presence of multiple machine parts, all located within a 
limited space around the building drum. 
Moreover, it has been found also that the distribution and the uniformity 
obtained by the metallic cords of the reinforcing plies are not entirely 
satisfactory because the cords become arranged on the carcass with 
variations in the angle of inclination that are significant and 
undesirable in a radial tire which must be resistant to all kinds of 
stresses during its performance on a motor vehicle wheel. 
It is an object of this invention to provide a process and apparatus for 
manufacturing radial tires which are devoid of the foregoing 
disadvantages. Another object of the invention is to provide an improved 
apparatus and process for making radial tires for motor vehicles.

The foregoing objects and others are accomplished in accordance with this 
invention, generally speaking, by providing a process for manufacturing 
radial tires comprising a radial carcass, a reinforcing structure with at 
least two layers of metallic cords which constitute the belt, the cords of 
the two layers being criss-crossed with each other, and symmetrically 
oriented with respect to the longitudinal direction of the tire, and a 
tread, the process comprising the steps of: 
(a) building-up the carcass in a cylindrical configuration on a main 
expandable building-drum; 
(b) shaping the carcass, in its non-vulcanized state, into a toroidal 
configuration; the process being characterized by the fact of comprising 
the further steps of: 
(c) disposing and winding into a cylindrical configuration, the belt 
(formed by two layers of metallic cords) on an auxiliary expandable drum 
with a diameter equal to the external diameter of the carcass, after the 
first toroidal configuration on the main building drum: 
(d) expanding the expandable part of the auxiliary drum, and maintaining 
the expandable part and belt in slidable contact, and while in the 
slidable condition, taking the belt from its first cylindrical 
configuration to a toroidal configuration, with an equatorial development 
which is greater than the equatorial development of the carcass after the 
first shaping; 
(e) contracting the auxiliary drum; 
(f) extracting from the auxiliary drum, the annular layered-band comprising 
the belt and the tread which has been wound on the belt after step (d); 
(g) transferring and centering the annular layered-band, in correspondence 
of the equatorial plane of the carcass on the main drum; 
(h) expanding the main drum, and proceeding to make a second toroidal 
shaping of the carcass until taking the carcass crown into contact with 
the corresponding toroidal surface of the belt; and 
(i) vulcanizing the so-formed tire in a mold, and under pressure. 
The fundamental characteristic of the invention involves expanding the 
belt, without the tread and the carcass, while taking care, at the same 
time, to exercise uniform pressures on a belt by means of an expandable 
surface with slidable characteristics that maintain, in the expansion 
step, a practically negligible friction when there is contact between the 
expandable part of the auxiliary drum and the elastomeric part of the 
overlying layer that contains the metallic cords. 
This process can be carried out with an expandable part of the auxiliary 
drum formed out of a metallic material for example, with a plurality of 
sectors in steel or other metal having a surface with an anti-adhesive 
covering, that is preferably scored; or of any other material, the 
behavior of which is equivalent to that of a metal, as far as concerns 
`frictional effects` when in contact with the belt to be expanded. 
According to the process described above, the metallic cords of the 
reinforcing layer are more freely disposed and more uniformly layed than 
are cords prepared by the `known` processes. 
As a matter of fact, in the step of expanding the belt, the metallic cords 
are not obstructed in their movement of setting, due to the presence of 
the tread and to the underlying carcass--the elastomeric composition of 
which, in the processes of the prior art, originated a high friction when 
in contact with the elastomeric part of the belt, and which resisted 
hence, free expansion, causing negative results, such as preventing a 
uniform distribution of the cords. 
The process of the invention, can also be applied among other things, to 
the manufacture of radial tires which comprise on the carcass (besides the 
belt with metallic cords), further reinforcing layers--for example, one of 
several layers of cords that are parallel to each other and disposed in a 
longitudinal direction. These cords can be either metallic, or a textile 
material which shrinks under the action of heat. 
The manufacturing process for the tire with textile cords is characterized 
by the fact of applying and winding around the already expanded belt, at 
least one layer of textile material cords, and finally wrapping the 
tread--for constituting the annular layered band for being transferred to 
the main drum, where the carcass after its first toroidal shaping, has 
been made ready. 
This process, moreover, brings about the advantage again, of manufacturing 
a tire possessing particular characteristics of comfort and uniform 
behavior because the metallic cords, not being impeded in their movements 
and by the presence of the textile cords (such as, for example nylon 
cords), are able to settle during belt expansion; this results in very 
small variations in the inclination angle. 
A further object of the invention is to provide an auxiliary expandable 
drum for separately shaping the reinforcing structure and the tread for 
manufacturing radial tires comprising a tread, a radial carcass and a 
reinforcing structure which has at least two layers of metallic cords 
criss-crossed with each other and forming the belt, the carcass being 
produced on a main expandable drum where it is transformed from a 
cylindrical configuration into a first toroidal shape, and then, to a 
succeeding second toroidal shape for transforming the external equatorial 
development of the carcass into a higher value than that obtained during 
the first shaping; the auxiliary drum being characterized by comprising 
means for assuming and for passing from a cylindrical configuration into a 
toroidal configuration, in such a way as to transform the belt, wound onto 
the auxiliary drum which has a diameter corresponding to that of the first 
toroidal shaped carcass to the toroidal shaped configuration corresponding 
to the carcass crown of the second shaping, the said means comprising an 
expansible part in a metallic material, or material that is equivalent to 
metal as regards the `frictional effects` during the contact between the 
expandable part and the belt, during the passage from a cylindrical 
configuration into a toroidal configuration. 
In a preferred embodiment, the means for assuming and for making the 
auxiliary drum pass from a cylindrical configuration to a toroidal 
configuration comprises a plurality of supports disposed circumferentially 
and parallel to the drum axis, assembled with each other with interposed 
void spaces, a plurality of convexed sectors comprising the expandable 
part of the means with a total convexed surface disposed below the upper 
surface of the supports in the cylindrical configuration of the auxiliary 
drum, means for the passage of the sectors between the void spaces and for 
the expansion of the sectors up to a position above the supports for 
determining the toroidal configuration of the auxiliary drum. Still 
another object of the invention is to provide a plant or apparatus for 
manufacturing radial tires comprising a tread, a radial carcass, and a 
reinforcing structure of at least two layers of metallic cords 
criss-crossed one with the other, for forming the belt; the plant or 
apparatus comprising a main `known` per se expandable drum--for converting 
the carcass from a cylindrical configuration to a first toroidal shape, 
and then to a subsequent toroidal shape having a higher value than the 
first shape, said auxiliary drum being adapted, as first stated, for 
assuming the configuration from cylindrical to toroidal and for taking the 
layer of metallic cords from a cylindrical configuration to a toroidal 
shaping of the carcass; means for transferring the annular layered-band 
that is comprised by the reinforcing structure and by the tread from said 
auxiliary drum onto said main drum, after the first toroidal shaping of 
the carcass, and prior to the second toroidal shaping of the same carcass. 
In the description given below, reference is made to one embodiment of the 
tire of the invention illustrated in FIG. 1 and to one embodiment of the 
corresponding manufacturing plant illustrated in FIG. 2. 
The illustrated `finished` tire in the drawing has a single-ply radial 
carcass 3 having its extremities turned up around the beads 4 and 5, a 
reinforcing structure 6, and a tread 7. 
The reinforcing structure 6, has an annular belt constituted by two layers, 
of rubberized canvas 8, 9, comprising metallic cords criss-crossed one 
with the other and inclined with respect to the equatorial plane at an 
angle equal, for example, to 21.degree.. 
Obviously, the reinforcing structure can have other reinforcing layers such 
as, for example, strips of nylon cords with a longitudinal direction that 
are omitted here without adversely effecting in any way comprehension of 
the invention. More generally speaking, the plant 2 for manufacturing tire 
1, comprises a basic or main drum 10 for building first the carcass 3 in a 
cylindrical configuration and then transforming it into a first toroidal 
shape; an auxiliary expandable drum 11 for shaping the belt first into a 
cylindrical configuration with a diameter corresponding to the maximum 
diameter of the carcass in the first shaping step, and then for converting 
the belt into a toroidal shape; means 12 for transporting the annular 
layered-belt constituted by the reinforcing belt and the tread from the 
auxiliary drum to the main drum with the mid-plane of the annular 
layered-band corresponding to the mid-plane of the carcass of the first 
shaping step in such a way as to be able to proceed successively with the 
second toroidal shaping of the carcass, until when the carcass crown 
reaches, and is disposed against the corresponding internal surface of the 
belt. 
The main drum 10 (see FIG. 3) is constituted by an expandable membrane `B` 
and by device 13 for blocking the beads comprising two C-shaped rings 14 
and 15 which are adapted for the purpose of fitting-on and for 
successively blocking the beads of the carcass' cylindrical sleeve 
`M`--which modalities are amply described and illustrated in the Italian 
Pat. No. 957,079 and its corresponding U.S. Pat. No. 3,925,141, assigned 
to the assignee of this application. 
The auxiliary expandable drum 11 (see FIG. 4) has means for allowing the 
carcass to assume a cylindrical configuration, and for passing from the 
cylindrical configuration to a toroidal one. 
In the preferred embodiment, the means comprise a plurality of supports for 
the belt constituted by a cylindrical supporting structure 16 in the form 
of a comb with teeth 17, and an expandable part constituted by a plurality 
of sectors 18 having a convexed surface 19 disposed radially with the 
overall surface below the upper surface of the comb 16 in its initial 
at-rest position (see FIG. 4), and thence, shifted radially outwards, 
towards the toroidal configuration, through expansion means 20 (see FIG. 
4) illustrated in detail in FIG. 6. 
The comb-like structure carries out various functions as listed and 
explained below: 
(a) With its external cylindrical development it acts as an element for 
measuring the length of the belt, the first cylindrical configuration of 
which (for the actual purpose of the invention), is required to have an 
external diameter corresponding to the maximum diameter of the carcass, 
after its first toroidal shaping. 
(b) With its external comb-shaped development having teeth 17 preferably 
occupying half of the total cylindrical surface, it constitutes a 
practically continuous support for the uncured belt thereby obviating 
dangerous deformations; and, at the same time, owing to the presence of 
void spaces between comb-teeth, it permits expansion of the sectors in 
order to make the auxiliary drum assume the toroidal configuration after 
the cylindrical configuration. 
(c) The practically continuous cylindrical external development allows 
overlapping of the belt edges through-out their entire length with the 
advantage of having a perfect joint which cannot be obtained, for example, 
if the layers of the belt are wound onto the convexed sectors for the 
surface obviously would only constitute a partial support for the width of 
the overlying layers and would render the relative junction of the edges 
imperfect. 
(d) It acts as a centering element for the belt, for example, in providing 
a circular ridge 21 (see FIG. 4), defined by an orthogonal plane at the 
axis `1` of the auxiliary drum, against which one side `L` of the belt is 
maintained, while the belt is wound onto the drum. 
The plurality of the sectors 18, comprise a convexed surface 19 of metallic 
material--particularly in steel, or any other material that has 
"frictional effects" which are equivalent to a metal during contact 
between the surfaces of the sectors in expansion and the belt; or yet as 
another example, in polytetrafluoroethylene (known commercially as 
"Teflon"), that has special `non-stick` characteristics, or in some such 
equivalent materials whose surfaces have duly undergone a special process 
for rendering them slidable, with respect to the belt. 
Generally speaking, the surface of the sectors (regardless of what material 
they are made of) must have a minimum friction when contacting the belt in 
expansion, in such a way as to uniformly settle the metallic cords during 
their passage from the cylindrical conformation to the toroidal 
conformation of the belt. 
The sectors 18 are designed to have a special form for permitting deep 
penetration of the convexed surface 19 between the teeth 17 of the comb 
16, and into the void spaces found between the teeth, and hence, to be 
able to expand the belt with the greatest uniformity possible. 
Each sector, with regard to this, comprises two longitudinal substantially 
identical wells 22 (see FIG. 5) having their form corresponding to that of 
the comb-teeth with each well having a depth (measured radially to the 
auxiliary drum between the innermost surface of the teeth and the bottom 
of the relative well in its at-rest position), at least equal to the 
radial shifting of the sectors, for passing from the initial position 
below the comb (see FIG. 4) to the upper position that is coincident with 
the toroidal configuration of the auxiliary drum (see FIG. 5). 
The means 20, for the radial expansion of the sectors 18, comprise, for 
each sector 18 (see FIG. 6), two levers 23 and 24, a pilot shaft 25, and a 
mechanism for actuating the lever 26. 
The two levers 23 and 24, are oriented to cross, one over the other, and 
they are disposed in planes that are radial to the drum. The levers have 
first ends 27-28 hinged to the extremities 29-30 of the relative sector 
18, and second ends 31-32 that are actuable by the fluid-dynamic pistons 
33-34 of the actuating mechanism. 
The pilot shaft 25, is extended radially to the auxiliary drum and 
comprises an upper end 35 attached to the center of the relative sector, 
and a lower end 36 that is slidable in an internal position found at the 
center of the auxiliary drum. 
There are also provided blocking means which are adjustable, for varying 
the degree of the expansion path for the sectors 18 of the relative belts 
in tires having measurements which are diverse to each other. 
With the aid of a special handle `D`, the rotation of the screw 28, in one 
sense or in the contrary sense, varies the initial reciprocal distances of 
the lever ends 31 and 32, and the successive path of the pistons, varies 
the degree of the expansion of the sectors 18, as is clearly shown in FIG. 
6. In this Figure, in the upper part, there may be seen the minimum of the 
expansion travel of the sectors 18, depending upon a predetermined 
rotation of the screw; and in the lower part, may be seen the greatest 
expansion travel of the sectors 18 that abut against the stop-limit 
surface 39 by means of another predetermined rotation of screw 38. 
The return movement of the sectors is also actuated by the special action 
of the cylindrical springs `m` that are adapted for returning the ends 
31-32 of the levers back to their original position when the actuating 
fluid is extracted from the relative cylinders. 
The contraction of the sectors is also regulated by another screw 38"; the 
depth of the screw on a corresponding threaded surface 38"' of the drum 
determines the arresting of the lever ends, before the corresponding 
sector can proceed to interfere with the underlying profile of the teeth 
17 in the comb 16. 
Means adapted for withdrawing the comb 16 by sliding it off the relative 
teeth 17 and through the wells 22 of the sectors are provided on the 
auxiliary drum for completely expanded sectors 18. 
These sliding means comprise (see FIG. 6) a plurality of horizontal 
guide-bars 40 connected to a first and a second plate (41 and 42) co-axial 
with the auxiliary drum; a third plate 43 mounted to slide over the 
guide-bars 40; a fluid-dynamic control, connected to the fixed structure 
`F` and whose rod 45, is connected to the third plate 43 by means of the 
interposition of bearings 46 adapted for rotating on corresponding rolling 
tracts made directly on parts fast with the third plate and on the rod 45. 
Comb 16 is fixed on the third mobile plate 43, co-axial to the auxiliary 
drum. 
When the auxiliary drum is in its steady state condition, after belt 
expansion, the return path of the rod 45, in its relative cylinder, 
carries along with it the third plate 43, and withdraws the comb 16 from 
the `full-line` position to the `broken-line` position of FIG. 2; or from 
the broken-line position to the full-line of FIG. 6. 
The auxiliary drum 11, moreover, comprises means for temporarily blocking 
under pressure, the belt that is wound around the auxiliary drum. 
In a preferred embodiment, the blocking means are magnetic means 47, 
forming additional supports (see FIG. 5) in the form of the teeth of comb 
16. 
The means 12 of apparatus 2, for transferring the annular layered-band 
formed by the reinforcing structure and by the tread, from the auxiliary 
drum to the main drum 10, comprise a transfer ring of the commonly `known` 
type, provided with a plurality of sectors 48 that are actuatable through 
the means of opportune levering mechanisms in such a way as to permit them 
to contract radially for drawing any annular shaped element; and also to 
expand for returning to the at-rest position and for releasing the same 
element. 
The movement of the rings 12 between the two drums, is regulated by the 
actuating system that comprises a motor 49 (see FIG. 2) with a chain 50 
wherein the ends 51-52 are connected to a supporting base 12' of the ring, 
which is slidable on an appropriate rail 53. 
The centering of the ring, with respect to the mid-plane of the main drum, 
is regulated by an extremely precise control-system based substantially 
(even though with a simplier solution) on the concept of the device 
described in the Italian Pat. No. 29324 A/76 and corresponding U.S. Pat. 
No. 4,131,402 assigned to the assignee of this application. 
According to the scheme illustrated in FIG. 2, the auxiliary drum and the 
main drum are disposed on a common shaft, and the two drums are actuated 
in rotation independently one from the other, with the usual friction type 
mechanisms that are associated to various gears for changing the relative 
velocity, according to what is required for the single operation to be 
effected. 
The transfer ring, in its turn, moves with its axis aligned with the drum 
axis. The functioning of the apparatus is as follows: 
At the beginning of the manufacturing cycle, the carcass, already formed 
into the shape of a cylinder `M` (see FIG. 3) is fitted onto the main drum 
10. 
For carrying out this operation, one of the two C-rings (14-15), is drawn 
apart in the direction of the axis of the main drum 10, and thence, after 
inserting sleeve `M`, the same C-ring is returned to a position for 
blocking the bead. 
In a further step, always on the main drum 10, fluid under pressure is sent 
to the inside of the drum cavity, in this way bringing about the expansion 
of the elastic membrane `B` and the consequent toroidal shaping of the 
carcass `M` (FIG. 7) with a diameter that results in being substantially 
coincident with the diameter of the cylindrical surface of the comb 16. 
Substantially simultaneously, either a little while before, or a little 
while after the said operations, there takes place (successively) the 
winding of the first and second plies over the auxiliary drum 11 (see FIG. 
4). 
Each of these reinforcing plies is slowly directed to the auxiliary drum 
put into rotation, while always maintaining one of the sides `L` of each 
ply in contact with the drum ridge 21, in such a way as to guarantee the 
exact alignment of the belt with respect to the mid-plane of the auxiliary 
drum. 
During this phase, the plies adhere, for their entire width, to the comb 
16, through means of `attraction`, to which the metallic ply cords are 
subjected due to the presence of magnents 47 inserted for part of the arc 
of the teeth 17. 
For the purpose of winding each ply, it is necessary to proceed by 
overlapping the ends, and by effecting the relative joining, thus 
obtaining an annular belt having an internal diameter that corresponds 
with the external diameter of the carcass, after the first shaping step. 
Before expanding the belt, the operation of compacting (or stitching) the 
two reinforcing plies, takes place. 
The stitching operation is advantageous to insure the desired optimum 
uniform distribution of the metallic cords. 
In fact, this `compacting` results in having adhesion between the two 
plies--through the elimination of any interposition of air between the 
plies themselves. In this way, during the subsequent expanding of the 
belt, any slipping of one ply with respect to the other is prevented, and 
hence, the risk that free movement in the setting of the cords in the 
innermost ply might be held-up or altered by the relative shifting of the 
upper ply is eliminated. 
Preferably, the `compacting` action is carried out with cylindrical brushes 
54 (FIG. 4) composed of filaments of a synthetic material, drawn close-to, 
and then brought under pressure onto the belt itself. 
This brush action, is particularly favorable because (although it has 
sufficient mechanical action for allowing the air entrapped between the 
two plies, to escape) it has, owing to its construction with synthetic 
filaments, a force of impact that does not deform the belt, and neither 
does it alter the alignment of the belt, with respect to the mid-plane of 
the auxiliary drum. 
Once this `compacting` step is completed, the belt expansion takes place 
through the following sequence. 
The fluid under pressure, is sent into the pistons 33-34 (see FIG. 6) of 
the actuating mechanism on the auxiliary drum in such a way as to draw the 
ends 31-32 of the levers 23-24, closer together, and to determine the 
raising of each of the sectors 18. 
The sectors 18 expand progressively, starting from their initial position 
below the comb 16 (FIG. 4) with a radial shifting that is perfectly 
regulated by the presence of the pilot shaft 25 that is compelled to slide 
into the drum brushing 37 (FIG. 6). 
Therefore, during the raising of the sectors, from the position of FIG. 4 
to that of FIG. 5, alignment is guaranteed, with continuity between the 
wells of the teeth 17 which determine in this manner a rigorous and 
complete penetration between comb and the convexed surface 19 of the 
sectors, until the convexed surfaces (of all the sectors) are brought 
radially to a position above the comb. 
Hence, there is obtained, with this step, the gradual passage of the 
auxiliary drum from a cylindrical configuration to a toroidal one and 
consequently, the belt expands between these two configurations, in a 
state of free slidability, into contact with the metallic surface 19 of 
the sectors 18. 
The state of slidability between the innermost ply of the reinforcement and 
the metallic material surface of the sectors is further favored by the 
characteristic of expanding the belt by means of a plurality of convexed 
surfaces separated by void spaces, and determined by the presence of the 
comb `teeth`. 
As a matter of fact, with this solution during the expansion step, these 
void spaces act similarly to canals adapted for permitting the escape of 
entrapped air, that has been `sucked in` in the course of the movement 
between sectors and inner ply; thus, any eventual effect of being held 
back or attached to the said inner ply attaching onto the sectors, is 
practically eliminated. 
The finished result, is a nonrestrained setting of the metallic cords, with 
the absence of any hindrance to their movement either above or below, 
during the belt expansion; and finally, the cords are distributed with the 
maximum of uniformity possible and in a manner that has never been 
obtained in the past. 
At the termination of the discussed expansion step, the auxiliary drum 11 
and the belt 6 are found in the condition that is illustrated in FIG. 5, 
i.e. a toroidal configuration, with the maximum diameter of the belt 
larger than the diameter of the carcass, after the first toroidal 
configuration on the main drum. 
In the same FIG. 6, there is represented the comb 16 withdrawn axially, and 
at a side with respect to the sectors after the various functions of the 
cylindrical support of the auxiliary drum, have ceased. 
Successively, there takes place the step of transferring the annular 
layered-band from the auxiliary drum to the main drum 10. First, the ring 
12 (FIG. 2) is transported, from its at-rest position towards the 
auxiliary drum until it is brought to the mid-plane in a centered position 
with regard to the annular layered-band; then, the sectors of the ring 12 
are contracted together for bringing them into close contact with the 
central circular portion of the tread, and successively, the sectors 18 of 
the auxiliary drum contract in such a manner, that the annular layered 
band becomes solid with just the transfer ring; finally, the ring 12 is 
shifted in the direction of the axis that is common to the two drums, up 
to the mid-plane of carcass 3 that is obtained in the first toroidal 
shaping on the main drum 10 (FIG. 7). 
Now, the further expansion of the carcass begins. This step is carried out 
once again with fluid under pressure inside of the membrane `B` until the 
carcass 3 is transported from the first toroidal configuration (FIG. 7) to 
the second configuration, wherein the carcass crown coincides with the 
corresponding internal surface of the belt 6. 
At the termination of this second shaping step, expansion of the sectors of 
the transfer ring 12, is effected--and hence, the drawing apart of the 
same ring from its at-rest position of FIG. 2. 
Immediately after this, on the main (or basic) drum 10, the usual rolling 
operations take place by means of metallic discs (not illustrated), 
following dispositions and sequence that are already per se `known`. 
At the end of the rolling step, the tread is approached and compacted even 
at the ends of the underlying carcass; and the finished tire is in the 
condition illustrated in FIG. 8, with the equatorial development of the 
carcass slightly smaller than what it will assume in the vulcanizing step. 
During the vulcanizing step, the tire that was already subjected 
previously to an equatorial lengthening of the carcass during its passage 
from the first to the second toroidal shaping step, is now subjected to a 
further equatorial lengthening in its passage from the second toroidal 
shaping step to the vulcanized tire and with consequent, further expansion 
of the reinforcing structure and the molding of the tire band. 
The plant 2 has been described according to a preferred embodiment; 
therefore, it is quite clearly comprehensible that certain of the elements 
can also be varied. For example, the cylindrical surface of the auxiliary 
drum 11 instead of having a comb form, can also comprise a plurality of 
sectors, the upper surfaces of which determine a cylindrical supporting 
surface for the belt. 
These sectors can be shifted radially towards the outside, and regulated 
with a predetermined path for the purpose of adapting the sectors for 
supporting the belts relative to tires having diverse measurements. 
Subsequent to the expanding of the belt, by means of the convex sectors, 
the cylindrical sectors can be contracted radially by shifting them. This 
nevertheless, will not at all interfere in any way, with the belt ends 
regardless of the tire size. 
Moreover, the main drum can be structurally different from the one 
described. For example, a drum adapted for receiving the radial plies of 
the carcass, and for constructing them first into a cylindrical 
conformation having the form of a sleeve, and then, into the two 
successive toroidal conformations can be used. 
Also the building drum may be one wherein the function of the expansible 
membrane is effected by the very same carcass, to the interior of which, 
fluid under pressure is directly introduced. 
Although the invention has been described in detail for the purposes of 
illustration, it is to be understood that such detail is solely for the 
purpose of illustration and that variations can be made therein without 
departing from the spirit and scope of the invention except as it may be 
limited by the claims.