Note: Descriptions are shown in the official language in which they were submitted.
1~641~0S
Background o~ the Invention
Thls invention rela-tes to a method for mak- -
ing radial ply tires o~ -the type including bias-
angled breaker plies and a 0 cap band and -
more specifically to a method for mak ing such a tire
in a single building stage and to the intermediate
article of manufacture so made.
The expressions "radial tires" and "radial
ply tires" as commonly used in the pneumatic tire
art may be said to include various tire constructions
having a carcass or body comprising one or more rein-
forcement plies of rubberized tire cords extending
from bead to bead wherein the cords in each ply are
substantially radial in orientation, i.e., the cords
are oriented substantially normal to the beads and to
the crown centerline of the tire. In a mono-ply ra- ;~
dial tire the carcass or body cords normally have ~0
bias angle, i.e., in the unshaped carcass they extend
perpendicular to the planes of the beads. In a two~
ply radial tire, the cords in each body ply are usually
oriented at oppositely disposed small angles of up to
10 with respect to the perpendicular to the bead ~ ;
planes, in which case the respective body plies are ~`;
said to have oppositely disposed bias angles of 80
or greater (but less than 90Q). In four-ply or heav-
ier radial ply tire constructions similar opposed ~ ;
orientation of the cords in successive body plies is ; ~-
usually employed. All of these body or carcass con~
structions are'contemplated within the scope and mean-
ing of the expressions "radial" and "substantially
radial"'as used herein. ;~
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i: -. . : ,, ~ .. .. . . .
- ~1364~S
Radial tires are generally constructecl with
a breaker or belt interposed between the crown region
of the carcass and the tread for- rein:forcing the lat-
ter such breaker being comprised of one or more
layers or plies o~ tire cords or cables which are
generally inextensible i.e., made of such materials as
metallic wire, glass fiber, rayon, nylon etc. In a
mono-ply belt, the cords or cables have a relatively
low bias angle of 0, i.e., they are oriented substantially
parallel to the planes of the beads and to the median
equatorial plane, or crown centerline, of the tire.
If the belt is of a multi-ply construction, similar
but opposed low bias orientation of -the cords or
cables generally at an~les ranging up to about 30
or so with respect to the median equatorial plane of
the tire are employed in successive plies. The more
recent of such tires further include a 0 cap band
positioned radially outward of the breaker struct~re
and beneath the tread which cap band serves to en-
20 hance both the geometrical uniformity and the rolling ~
properties o~ -the tire. Such a tire structure is ~-
shown, for example, in Canadian Patent No. 984,719.
In *he building of radial ply tires having
breakers and 0 cap bands incorporated in the crown
area of the tire, a two stage process is convention-
ally employed. During the first stage of building,
a cylindrical tire carcass is formed, the carcass
having o~e or more rubber covered cord plies anchored
to and interconnecting axially spaced, parallel, co-
axial bead cores, and a layer of rubber sidewall stock
3~ 69~8~5
on CaCIl sidc~ all area of th~ c~rcass interm~dla~e
th~ ever.lu~l cro~rn ~rea th~r~o~ and tlle ~wo ~ead
areas ~hereo~. ~uch a carcass is conventionally re-
ferred ~o as a ":~irst stage" carcass . During the
. 5 second stage o~ building~ thQ shape o~ the f~rst
stage carcass is chan~ed fro-. cylindrical to to-
roidal, and one or more rubber cove-ea cord breaXer
.
. plies, the cap band and a ru~ber tread slab are ad-
:- ded to ~he cr~.n po~tion of ~he ~ire carcass ~o ~orm
~ what is c~n~ren~ionally referred to ~s a "second stage'
. .
carcassO m e term "rubber' as used herein i~ intended
to cover natural and syn~hetic rubber and rubber-like
materials zs well as blends thereo~. The ~erm "cord"
as used herein is intended ~o ccver sin~le and mul- .
tiple s~rands, filaments, T,~7ires or cables of natural
t~ and~or syn~hetic tex~ile materials such as co~on,
rayon, ~lon, polyester, glass ~iber, nylon and the like~ ;
metal, and/or such other ma~erials as may be used as
reinforcements in pneumatic vehicle ~ires.
As above s~ated, ~he shape o~ the ~irst stage
- carcass is changed during the second s~age o~ build- .
ing from cylindrical ~o toroidal, and breaker plies~
the cap band and a rubber tread slab are added to
. . .
the tire carcass to form the afore~en~ioned second
2~ s~age czrcass. ~chines of the type presentl~ known
in the art for building tires frequen~ly utilize two
stations ~o perform this func~ion. The first station
is u~ilized to fabricate the breaker, c~p band and .
tread asse~bly by successively winding the various
. 30 elemen~s thereo~ abou~ a radially expansible and con-
.
, ...... . . . .. . . . .
L~_ 10648~5
tra^t~.ble building dr~m. l`he breaker~ cap band and
tread assembly is then conveyed from the ~irst sta-
tion to the second s-tation at which is positioned the
aforementioned cyllndrical carcass, the second sta-
tion including support and shaping disks and movable
conical shaping rings engageable with the carcass
sidewalls for shaping the first s-tage carcass into
the second stage carcass during inflation thereof.
The breaker~ cap band and tread assembly is then
positioned so as to encircle the eventual crown area
of the first stage carcass which is posit.ioned on the
aforementioned support and shaping disks. me car~
cass is then inflated and the crown area thereof ex-
pands into pressuri~ed contact with, and adheres to~
the inner surface o~ the breaker~ cap band and tread -.
assembly to form the desired second stage carcass.
The second stage carcass may now be deflated and re- -
moved from the support and shaping disks. m is two- .
stage building method has been necessitated by the .-
~act that any low bias angle breaker plies built into
~he un~ormed tire on the drum would necessarily have
to be stretched considerably in circumference during
the forming of the tire. While some of this stretch
can be accomplished, as in the forming of the body
plies of conventional tlres~ by the cords in the
breaker plies assuming a more nearly circumferential
orientation and moving closer together, some of it
is necessarily, because of the low bias angle of the
breaker plies, accomplished by the parallel slippage
as well a.s the pivoting action of the cords in the
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. : . , ,~ . .. . ..
-5- ~64805
breaker plies. ~en~ in the past, it has been at-
tempted to form completely dr~-built radial tlres
contalnin~ low angle brea~ers, it has been found that
the adhesion of t;he breaker pl~ cords to the adJacent
tire components resulted in uneven movement of the
cords and consequent malformation of the tires. In
the case of such tires which include 0 cap bands,
the problem has, of course, been compounded by the
fact that, since the cords comprising the cap band
are already substantially at 0 relative to the median
equatorial plane of the tire9 there can be no slippage
or movement toward a circumferential orientation and
because the cords o~ the cap band are inextensible,
they cannot stretch to accomodate the expansion of
the carcass.
Although tire making machines of the type
presently known in the art are efficient and produce
uni~orm, high quality, second stage carcasses, it
would be desirable, for economic reasons~ to be able
to build such tires in a single stage processes. The
desired economics would result from, among other rea- `~
sons, the ability to use existing single stage bui~d- ~ -
ing equipment, the fact that a lesser amount o~ expen- -
sive factory floor space would be required for the
necessary tire building equipment, and the fact that
fewer man-hours would be required for the buiIding of
a tire in a single stage.
Summar~ of the Invention
It is therefore an important obJect of the
present invention to proYide a novel and improved
'
~06~ 5
method ~or making a radial ply tire in a single building
stage.
It is a further oo~ect of this invention to pro-
vide a novel and improved method for making such a tire
on conventional single stage building equipment.
It is another important ob~ect of the present
invention to provide, as an intermediate article of manu-
facture of said method, an uncured, 0 belted, radial ply
tire.
Generally speaking the ob;ectives of the present
invention are obtained by the provision of a method for
making a radial ply tire in a single stage comprising the
steps of winding at least one ply of body tire cords around
a tire building drum to form a cylindrically shaped body ~ ~.
layer, the body tire cords extending substantially parallel
to the axis of the drum, serially wrapping an even multi-
plicity of plies of bias angled substantially inextensible
breaker tire cords around the radially outer surface of the
:: . .
body layer to form a breaker, the breaker tire cords being ~ :
parallel in each ply and oppositely disposed in adjacent ~
plies and forming a bias angle of between about 30 and 70 . .
with a plane orthogonal to the axis of the drum, helically
winding a strip of high "soft-stretch" reinforcing cord
tape around the radially outer surface of the breaker for
a selected plurality of full turns to form a cap band
having a desired axial width~ the tape strip being wound at
an angle o~ substantially 0 relative to the plane orthogonal
to the axis of the drum, and wrapping a trea~ slab around
the radially outer surface of the cap band so as to provide
a raw~ cylindrically shaped, tire carcass having a diameter
--6--
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~06~305
whlch is substantially less than the diameter o~ the crown
region o~ the corresponding cured, toroidally shaped, com-
pleted tire at the crown centerline thereof.
The ob~ecti~es o~ the present invention are also
attained by the provision, as an intermediate article of
manufacture, o~ an uncured radial ply tire carcass in the
as drum-built ~orm thereof comprising a bead anchored cy-
lindrically shaped body layer including at least one ply of
body tire cords, which tire cords extend substantially paral~
lel to the axis o~ the cylindrically shaped body layer, a :
breaker positioned circumferentially about the body layer,
the breaker including an even multiplicity of plies o~ bias
angled substantially inextensible breaker tire cords, the
breaker tire cords being parallel in each ply and oppositely ~ .disposed in adjacent plies and ~orming a bias angle o~ be- : -
tween about 30 and about 70 with a plane orthogonal to
the axis o~ the cylindrically shaped body layer, a cap band
positioned circumferentially about the breaker, the cap band .
being formed o~ a strip o~ high "so~t-stretch" rein~orcing ~;cord tape helically wound around the radially outer surface ;;
o~ the breaker ~or a selected plurality of ~ull turns J the
tape strip being wound at an angle o~ substantially 90
relative to the axis o~ the cylindrically shaped body layer,
so that upon ultimate radial expansion and axial contraction -~ :
o~ the carcass to transform the carcass from its cylindrical
shape to a toroidal shape, the reinforclng cord component o~
said cap band will extend at a substantially 0 bias angle
relative to the crown centerline of the toroidally shaped
carcass and will be straightened and tautened and tightly
embrace said breaker, and a tread slab positioned circum- .
~. .
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1(~ti48al5
ferentially about the cap band.
Brief Description of the Drawin~s
The foregoing and other obJects and features of
the present invention will be more clearly understood from
the following detailed description thereof when read in con-
junction with the accompanying drawings, in whicho
Figure 1 is a partially sectioned perspective view
of a raw, cylindrically shaped ~ire carcass, in its as built
form, on a building drum, made in accordance with the method
of the present invention;
Figure lA is an enlarged, partially sectioned, per-
spective view of a portion of the carcass illustrated in
Figure l;
Figure 2 is a sectional plan view of the intermediate
article tire carcass of the present invention illustrated `~
in Figure 1 and taken along lines 2-2 thereof;
Figures 2A and 2B illustrate modifications o~ the
tire carcass illustrated in Figure 2; ~:
Figure 3 is a fragmentary, diagrammatic, perspective ~ ~
view of a six-cord high "soft-stretch" tape used in the i .
manufacture of the tire carcass illustrated in Figure 1
according to the method of the present invention; and .~
Figure 4 is a partially sectioned perspective view ~.
of a cured, toroidally shaped, completed tire made according
to the method of the present invention.
Al ' ~ 8
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-9 1~64805
Descri~tion o~ the Preferred Embodiments
., .. . , , . ~
Referring now to the drawings, wherein like
reference numerals denote coxresponding parts through-
out the several views, Fig. 1 illustrates a partially-
sectioned perspective view of a ra~J c~lindrically
:'
shaped tire carcass 1 in its as-built form on a low
diameter building drum 3. The method for making a
radial ply tire in a single stage is, in i;he initial
stages of the building operation, generally conven-
- 10 tional. The first step is to wind at least one ply~
and preferably two plies, 5 and 7, of body tire cords,
which cords extend substantially parallel to the axis,
indicated at A-B, of the drum 3, around the drum
about which a rubber liner 9 (Fig. 23 has been wrap-
ped, to form a cylindrically shaped body layer. The
tire building drum 3 is of the type conventionally
used in the tire building art ~or first stage tire
building. The associated carcass components such as
the bead cores, chafer and apex strips~ etcO~ lndicated
generally at 11 (Fig. 4), are also assembled on the
building drum which may be o~ the expandable and con-
tractible type and may be either a flat drum or a
shoulder drum. The term l'low diameter" is here used
with respect to the drum to signii`y that the diameter
of the drum, and thus that of the generally cylin~ri-
cal carcass built thereon, is appreciably smaller than
the ~inal diameter to which the tire will be radially
expanded when being shaped into its desired toroidal
form as an ad~unct of the curing operation in the mold~
The next step is to serially wrap an even multiplicity,
_g_ ~ :
. .
-lo~ ~6480~
o~, ~or example, ~wo, plies 13 and 15 of biased ~ngled
breaker tire cords which may, ~or example, be of steel,
which is ~ubstantially inextensible around the radially
outer sur~ace of the body laye~r to ~orm a breaker struc-
ture 16. me breaker tire cords are parallel to one
another in each ply and are oppositely dlsposed in ad~a-
cen~ plies, and the angle they ~orm relative to the plane
orthogonal to the axis A-~ of the drum 3 i~ between about
30 and about 70~ and, in the embodiment illustrated,
is about 40. The next step is to helically wind a strip
o~ high "so~t stretch" reinforcing cord tape 17 (Fig. 3)
around the radially outer surfa~e of the breaker struc-
ture for at least a selected plurallty of ~ull turns to
form a cap band 19 having a desired axial width. The
~ape 17, which is long~tudinally extensible by between
abou~ 30% and about 75% without stretching the cords
thereo~ is wound at an angle o~ substantially 0 and,
in a~y e~rent, less than 2, relative to the plane orthogo-
nal ~o the axis o~ the drum~
me high "soft stretch" tape 17 which ls used
to form the cap band 19 is o~ the type disclosed ln
Canadian Patent ~o. 967,341, and a ~ragMentary diagram-
matic, perspective ~iew o~ a six-cord high "so~t-
stretch" tape used to make the cap band herei~ is
~-lustrated in ~ig. 3. 0~ course, any tape possess-
ing the required charcateristics would b0 satisfactory
~or use~ Generally speaklng, such a tape would com-
prise a continuous~ longitud~nally extensible strand
of one o~ more substan~i.ally inextensible cords 21
each having formed therein a multiplieit~ o~ undula
-10-
. . ~- . . .
6~L~il0S
tio~s which in any glven str~ight length of the tape
are substantially planar, the undulations preferably
being o~ a generally sinusoidal nature. The term `~
"soft stretch" is used herein to denote the abillty
of the tape to be longitudinally considerably extended
by the straightening of its component cord or cords
without the latter being stretched. The tape 17 in-
cludes the required number of individual cords 21,
each of which may be untreated or may have a coating
of rubber or latex or other rubber-adhesion promoting
material applied thereto and is made so that the ~inal
tape has the desired stretch ratio (the ratio of straight~
ened cord length to unextended tape length). A rela-
tively weak and frangible cotton or like yarn or thread
23 holds each of the cords of the tape in its unduiat-
ing state and, where the tape 17 includes a plurality
of cords 21, more than one of these cords may also be
tied to each other by the stitches 23. In a preferred
version of such a plural-cord tape used to form cap
band 19~ the cords 21 are disposed side by side with
the unduIations of laterally ad~acent cords in parallel
planes and out of phase with one another. To enhance
the stability and integrity of the tape a second rela~
tively weak and frangible cotton or like thread or yarn
(not shown) may also be woven into and held by the afore-
mentioned stitches. This second yarn, which extends the
length o~ tape is, however, in almost a straight condi-
tion, with only minimal undulation. Each cord may also
be provided with a multiplicity of longitudinally spaced
locally weakened portions to enhance its abillty to be
-11- .
~ .
-12- 10 ~ ~8~ 5
stretched and elon"ated som~what ~fter be~.ng fully
straightened. l~e ~/eakening of the cord portions,
whlch may be effected mechanically, chemically or
othe~ise is accomplished in such a manner as ~o leave
the portions with a relativel;y low residual tensile
strength, generally on the order of about 5~, to 20~
of their pre-wea~ened or full tensile strength. For
the production OI any given tire, the weakening inter- -~
val, i.e., the cord length between successive weakened
portions is selected and preset to be di~ferent from,
but not equal to a regular fractional multiple of, the
ultimately intended circumferential length of a full
turn of the cap band 19 in the fini.shed tire.
The tape winding operation may be either uni-
- 15 directional or bidirectional with reference to the
axis of the building drum and the winding is continued
until the tape-constituted cap band structure extends
over the desired width of the medial region of the
cylindrical carcass. It will be understood that the ~. :
tape 17, once properly laid on the breakers 16~ will
not twist or shift out of its wound-on position, and
the use o~ a tape of plural-cord width will enable a
relatively large number of cords to be applied with
each turn of the tape.
It should be noted, merely by way of example~
that it has been found that for most standard rim
size 0 belted passenger tires which are completely
built in a flat bard form in a single stage building
operation prior to being shaped, a tape having a stretch
ratio of between about 1.5 and 1.9 (50% and 90~) pro-
-12-
-13- ~ ~ 6~ ~ S
; vides satlsractory results. It will also be under-
; stood, however~ that for certain t~)es of tlres the
building operation may dictate the use of a tape hav-
; ing a s-tretch ratio which may be as low as about 1.2
(2~,~), while for other types the stretch ratio may
have to be as much as 4 (400~).
Prior to windlng the tape strip 17 helically
around the brea~er 16 which has been wound onto the
body layer, the breaker cords are stitched down (ad-
hered) in the axiall~ central portion of the breaker.
It has been found advantageous to stitch the b~eaker
down in the area of one inch (1") on each side o~ the
axial center line thereof so as to prevent shifting -~
o~ the breaker 16 during the pantographing of the
cords therein ~Thich occurs during the shaping o~ the
cylindrical carcass into the toroidal tire.
The raw, cylindrically shaped tire carcass is
now completed by wrapping a tread slab 25 around the
radially outer surface of the cap band 19 and the
tread splices are stitched (adhered) under conditions
insuring that no undesired bunching of the cap band
turns will occu~. Thereupon, the raw or green tire
in its as built form is removed from the building drum
and is ready to be subjected to the final shaping and ~
2~ curing operation. ~ -
When a 0 cap band raw ti.re built by the above
described method is radially expanded and axially con-
tracted into its final toroidal shape (either in the
curing press or prior to its being put thereinto),
the cap band forming structure defined by the wound
-13-
,4~3~5
on tape iS3 0~ course, sub~ect to the same type o~
radial expansion. This expanslon almost lmmediately
causes the weak stabilizing or stitching threads or
yarn 23 to be broken and they then have no ~urther
function in either the process or the tire, although
of course they remain in the tire. Thereupon, as the
expansion of -the tire continues, the cords 21 lose
their undulations and are ultimately completely
straightened out to define the cap band 19.
In this connection it should be noted that
whether the tire is to be cured in a segmented mold,
in which case the cap band expansîon will be substan-
tially completed before the mold is closed, or whether
the tire is to be cured in a standard unsegmented
"clam~shell" mold, in whicll case a small further ex-
pansion will ta~e place after the mold is closed~
the tape used may have a "soft stretch" or str~tch
ratio as nearly as possible exactly equal to that
actually required for the full radial ex~ansion.
Preferably, however, the tape 17 used will normally
have a stretch ratio somewhat less than the ~ull ex-
pansion ratio, in the order of between about 1% and
about 3~ less, so that the cord 21 becomes ~ully
straightened and the undulations disappear there~rom
shortly before the shaping operation is completed.
In such a case, of course, during the final expansion
o~ the tire, e.g., upon ~he forcing o~ the tire agains-t
the mold surfaces under high internal pressure a~ter
the mold is closed, the cap band cords will be sub~
~ected to fairly high tensile stresses and elongate
: :
-15~ 5
to the ext..ent required. Whe~e the cords, by virtue
o~ the construction and the stress-strain characteris-
tics of the cord material, can accommodate the result-
ant strain and elongation t~rithout exceeding their
elastic limit, the fact that they may be unweakened
will not lead to any problems. I~ere, on the other
hand, the cords are locally ~reakened, they ~il]. addi-
tionally have an increased ability to undergo a "hard
stretch" without adverse effect, i.e., they will be
able to elongate either, for example, hy the strain
of the cord material or hy actually breaking at one
or more of the locations o~ the various weakened por-
tions thereo~, or by a combination of these and simi-
lar characteristics. ~ney weakening o~ the cords o~
the tape 17 at a multiplicity o~ longitudinally spaced
pOilltS as described thus can be seen to provide a mar-
gin o~ safety, due to the presence of ~rhich a possible
choice.of a tape stretch ratio somewhat lower than
ordinary relative to the tire expansion ratio can be
compensated for and thus tolerated.
,. .
By helically winding the longitudinally exten-
sible tape 17, the final cap band 19 is devoid o~
splices, the absence o~ which splices leads to a greater
degree o~ uni~ormity and dynamic balance in the ~inished
tire. Moreover, the 0 belt or cap band leads to an-
- other advantage~ that is, a maximized hoop modulus of
the tire in the circumferential direction relative to
the hoop modulus which a tire utilizing only biased
belts directly under the tread would have.
Al~hough a cap band 19 having an axial width
.
-15- .
: ,.
-16~ 6~5
le~s than that of the underlyin~ breaker, comprls~d
of ~lies 13 and 15~ ~ay be utilized it ls :;r.o~rn thæt
many types of tires, e~pecially ra~ial pl~ carc~.ss
tires in which the tread is, as hereinJ re~nforced
by a breaker 16 composed o~ superposed, mutually crosse*~
rubberized plies of parallel substantially inexten~lble
cords or cæbles, often fail at high speeds because
separa~ions occu;^ in the s:noulder zones 27 (Fig.
. o~ the tires where the edges OL ~he breake~ plies
are located. Such ply sep_rations are due to ~he
cord ends at the ed~es o~ ~e breaker plies 13 ~nd
- 15 beco~ing detached ~rom the surrounding rubber under
the comb~ned effect of centri~ugal force acting on the . :
re~ flexing of the tire and heat buildup ln ~he tire.
~his result is made even more likeLy ~Ihere, as her~
l~ ~.'. the cords or cables in the breaker plies, 13 and 15~ . .
. which ~re disposed oblique~y ~o the median ~quatori7.1
plane o~ the ultimately to~o~dally shaped completed
t~re, have~ by virtue of the plies being cu~ obliquely
w~tn respect to the longitudinal d~rection o~ the cords
: . therein, a natural tendenc~ to spread apart a~ their
cu~ ends. The edges of ~he breaker pl~es 13 and 15
thus const~tute zones where the cut and ~ree ends of
- . the re~nforcin~ elements, ~hat is~ the cox~s or cables~
by friction and by cutting , ca~se breaks both ~n the
carcess ~lies 5 and 7 and in the rubber of ~he tiresO
~ere the tires which result Prom the method and inter- :
mediate ~rticle disclosed nere~n are to be utilized in
. hi~h ~p~ed service it is zdvantageous ~o LOrm the c2p
ba~ 19 so ~hat its axial w~dth is a~ least 2s great as,
-16-
. .
, .. . . . . . . . ..
-17- ~0~i48~5
and pre~erabl~ greater than5the width of th~ breaker
160 Such a construction will enable the 0 cap band
19 to minir~ze the detrimental ply edge separztion.
Due to the fact that tapes of the type herein
described and utilized are not convenientl~ made with
more than about 4 or 5 cords 21 therein, when it i5
desired to utilize in the building of the cap band 19
o~ the instant invention a tape 17 having a relatively
high number of component cords 21, such a tape 17 may
be made of a plurality of tapes of lesser cord numbers,
with these lesser cord tapes being cemented or other-
wise adhered to one another in a side by side rela-
tion. In this regard it is appropriate to note that
~f such a side by side relation of low number cord
tapes is utilized, it is advantageous to offset the
lo~Y number cord tapes relative to one another so as
to cause the undulations of the respective adjoining
side cords to be out of phase with one another.
As shown in Fig. 2 the tape 17 forming the cap
band 19 is preferably wound with the turns of the band
forming structure spaced slightly from each other by a
gap 29 o~ predetermined width, the reason for which
will be discussed below.
It will be understood~ of course, that in order
to achieve th~ stated orientation of the tape turns,
that is in a direction as nearly orthogonal to the axis
A-B of the drum and the ca~cass as feasible~ and thus
as close to the truly circumferential direction as pos-
sible, it is necessary to insure that the helix or
winding angle of the tape be as small as possibleO
-17-
-1~3- 3.0641!305
For the pu~ose of the instant invention this means
the helix angle may not be greater than about 2 and
~s prefer~bly less than 1. 1~e magnitude o~ the
helix angle will basically be a fu~ction o~, on the
one hand, the width of the tape indicated at 31,
plus the width of the gap 29 between two adjacent
turns of the tape, and of, on the other hand, the
diameter of the dr~m 3~ these parameters defining,
respectively, the lead of the helix and the length
of one turn o~ the tape around the circumference of
the drum. m us ~or example, a tire built on a 15"
diameter drum and including a cap band forming struc-
ture utilizing a rubber coated rayoll cord six cord
wide tape, the width o~ l~hich is approximately 0.3",
wound "on end" with a gap of approximately 0.1", will
have a winding angle of approximately 1/2, this angle
being the arc tangent of the quotient of the lead o~
the helix divided by the circun~erence of the drum,
i.e~, approximately 0. oo8s .
It is further deemed advisable to effectively
skive the tape at the opposite lateral edges of the
band forming structure so as to minimize any possible
discontinuity in the rubber to cord stress transfer in
the ultimate -finished tire~ mis result is accomplished
by peeling away and cutting off at each end o~ the tape
a predetermined length of the end region of the later-
ally outwardly facing tape component.
Turning once again to the spacing 29 between
the tape windings it will be remembered of course that
the cylindrical carcass will be radially expanded into
-18-
-19- ~L06~L805
a toroid~ During the shaping operation the cords
straighten out and the cap band ~orming structure
becomes some~at narrower. It will be apparent,
therefore, that :it is to fa~ilitate this narro~^ring
and at t~.e same -time prevent the cords ~rom bunch-
lng up at indeterminate locations across the width
o~ the cap band that the winding gap between the
turns of the tape in the cap band forming structure
is provlded. The ~idth of the gap is, of course, pre-
determined and selected to yield the desired cord den-
sity in the final band ~ithout ~mduly increasing the
helix or winding angle. Nevertheless, it should be
understood that the gap may be either entirely omitted
or not speci~ically cont.~ol~ed to be uniform through
out i~ some bunching of the cords and the resultant
non~uni~ormity o~ the band 19 can be toleraked. Fur-
ther, it will be understood that gaps as large as
three-quarters of one inch, and even slightly larger,
depending on tire ~ize and tape width, may be utilized.
mus, a tire as small as one built on a 13" diameter ~.
drum and including a tape as wide as a nine cord wide
tape, the width o~ which is approximately 0045", would
have a winding angle, i~ a three-quarter inch ~ap were
utilized, o~ 1.7.
It will be understood that although only a
- mono-ply cap band has been illustrated, a m~lti~ply
cap band 19 may be provided mis may be accomplished,
for example, by, after a desired axial width cap band
19 is provided by means o~ khe above described helical
winding of the tape 17, continuing to wind the tape
-19~ '
-20- ~4~5
back onto itself a-t the same hellx angle. An alterna-
tive method is to sever the tape 17 after a cap band
19 having a desired axial ~ridth is generated and to
begin the winding process again, the second ply belng,
of course, radially out~rard o~ the first ply. Yet
another method of providing a multi-ply cap band is
to utili~e a multi-ply or "nested" tape, i.e., a tape
in which a rnultiplicity of cords are arranged so that
the undulations of each cord are interfitted with, and
lie in the same plane as, the undulations of each adja
cent cord, and to helically wind this multi-ply tape a
single t:ime. The cap band 19 which results from this
last method will have a number of plies equal to the
number of layers of the ne~ted tapesO
15 - The next step in the inventive method to ar- -
rive at the structure shown in Fig. 1 is the wrapping
o~ the tread slab 2~ around the radially outer surface
of the cap band 19. This results in a raw, cylindri-
cally shaped, tire carcass 1 having a diameter which
is substantially less than the diame-ter of the crown
region of the corresponding cured, toroidally shaped,
completed tire 33, shown partially sectioned in Fig. 4.
m e ~inal step in the method for making the
desired radial ply tire is the step of simultaneously
shaping and curing said raw, cylindrically shaped,
carcass 1 to form the completed tire 33. It will be
understood of course that although the steps of shap-
ing and curing were indicated as occurring simultaneous-
ly, in actuality the shaping step begins as the curing
mold is closed onto the cylindrically shaped carcass 1
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, ~
".. . .
, : . .. : . . . . . :
-21- ~ ~6~8~5
whereas the curing step docs not commence until after
the shaping o~ the tire has commenced. Nevertheless
these two steps, which both occur in the curing mold
- are so closely related in tlme that, for the pu~oses
o~` this invention, they may be considered to occur
simultaneously. It ~Jill be understood of course that
this essentially simultaneous shaping and curing need
not occur. Thus, the tire may be shaped ln a com~
pletely separate step by using shaping means known
in the art, for example, the shaping bells illustrate~
in U. S0 Patent No. 3,676~262. In this e~ent only a
small portion o~ the total shaping will occur during
the curing operation, and then only if a non-segmental
"clam~shell" type mold is utilized.
Turning now to Fig. lA there is illustrated an
enlarged partial view of the completed raw carcass il-
lustrated in Fig. 1. In this view, more clearly than
in Fig. 1, it may be seen that the tape 17 includes
six adjacent cords 21~ the tape being, as noted above,
made up of two three-cord high or wide tapes. The gap
29 between each of the tapes 17 may be more clearly
seen in this view as may be the stitching yarns 23
hich, as previously noted, serve to maintain the cords -
21 in position`relati~e to one another until the tire
2~ is shaped.
Turning now to Fig. 2 there is shown a sectional
plan view o~ the intermediate article tire carcass f l`~
the present invention. This carcass is, o~ course, the ¦;
carcass 1 illustrated in Fig. 1 after the removal there- ¦~
f from the el~ansible and contractible building drum 3.
~- .
~21- -
~22~ 5 ~:
It ~ri] 1 be noted that in Fi.g~ 2, as was dlscussed with ;~
regard to Fig. lA~ the cap band 19 o~ the instant in-
vention is made up of a plurality of helical ~lindings
of undulating cord ~apes 17. :
Turning now to Figs. 2A and 2B if l:Jill be seen
that these figures illustrate modifications or alter- ~
native embodiments of the tire carcass illustrated in ~!
Figs. l, lA and 2. mus, Figs. 1, lA and 2 illustrate
a cap band 19 having an a.xial width less than that of
the breaker 17. Fig. 2A, however, illustrates a cap
band 19 having an axial ~idth equal to the axial width ~
of the 1Jidest of the breaker plies 13 and 15 comprising ..
the breaker 16~ In this regard i~ is appropriate to
note that although each of the figures herein illus-
trates a breaker structure comprised of breaker plies ~.
which are of progressively narrower axial width in the :~
radiall~ outward direction, i.e., the axial width of
pl~ 15.is less than that of ply 13, the tire may also
~: - ` be constructed with breaker plies each having the same -:
axial width as well as with breaker plies T~hich are i .
progressively axially wider in the radially outward
direction. Fig. 2B illustrates an embodiment of the
~; invention in which the cap band l9 has an axial width . .
greater than the axial width of the axially widest . ~.
~ 25 breaker ply of the breaker 16. This structure ma~ ad- . :
: vantageously be utilized in tires ~ntended for use at . ::
high speeds for -the reasons previously discussed.
Turning now to Fig. 4 there is shown a par~
tially sectioned perspective view of the cured, toroi- :
dall~ shaped, complete tire 33 made according to the
'
-22-
''.
-23- ~i4805
metho~l of the present inventionO The diameter of
the toroldally shaped completed tire, in the crown
region thereof, is approximatel~ 1.59 times as great
as the diameter of the cylilldrically shaped tire car-
cass 1 illustrated in ~ig. 1 In general~ ho~ever,
the diameter o~ a completed tire, in the crot~Jn region
thereof, will be between about 35"~ and about 70,'
greater than the diameter of the corresponding raw
tire carcass.
The angle made by the breaker tire cords o~
the completed tire relative to the cro~m centerline
or median equatorial plane (indicated at X Y) of the
completed tire 33 lS approximately 25-30, whereas
the angle the breaker tire cords made with the plane
orthogonal to the axis A-B of drum 1 was, in the em-
bodiment i].lustrated in Fig. 1, indicated to be about ~`
40. It therefore may be seen that the breaker tire
cords pantographed during the aforementioned shaping.
In general the breaker tire cords will pantograph down
during the shaping from between about 30 and about
70 with the plane orthogonal to the axis A-B of the
drum 3 to an angle of between about 20 and about 60
with the crown centerline of the completed tire 33.
It will be understood that the foregoing descrip-
tion of the preferred embodiments of the present inven-
tion is for purposes o~ illustration only, and the vari-
ous structural~operational and procedural features as
herein disclosed are susceptible to a number o~ modi~i-
cations and changes, none Or which entail any departure
from the spirit and scope o~ the present invention as
de~ined by the hereto appended claims.
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