U.S. patent application number 10/441471 was filed with the patent office on 2004-11-25 for method and apparatus for tread belt assembly.
Invention is credited to Currie, William Dudley, Delgado, Andres Ignacio, Girard, Jean-Claude.
Application Number | 20040231779 10/441471 |
Document ID | / |
Family ID | 33097963 |
Filed Date | 2004-11-25 |
United States Patent
Application |
20040231779 |
Kind Code |
A1 |
Girard, Jean-Claude ; et
al. |
November 25, 2004 |
Method and apparatus for tread belt assembly
Abstract
A method of building and transferring a tread 12 or a tread belt
reinforcing assembly 14 on a building drum 10 is disclosed. The
steps include applying at least one uncured tread component 12, 14
onto a radially collapsible building drum 10, inserting the at
least one uncured tread component 12 and the radially collapsible
building drum 10 into an open segmented mold 2 wherein a plurality
of mold tread forming segments 4 are radially expanded; contracting
the plurality of mold tread forming segments 4 pressing into the at
least one uncured tread component 12, 14; collapsing the building
drum 10; and removing the building drum 10 thereby transferring the
at least one uncured tread component 12, 14 into the mold. The
preferred building drum apparatus 10 has a portable radially
expandable and axially rotatable support means 20; a drive means 30
for rotating the support means 20 about the axis, a plurality of
arcuate or straight segments 22 slidably mounted over the support
means, the plurality of arcuate or straight segments 22 forming an
annular building surface 24; a means 40 for radially expanding and
contracting the radially expandable and axially rotatable support
means; a means for receiving and accepting the tread or tread belt
assembly while mounted on the plurality of arcuate or straight
segments 22 mounted onto the portable support means 20, the
receiving means 2 being a segmented mold 2 with radially movable
tread forming segments 4.
Inventors: |
Girard, Jean-Claude;
(Copley, OH) ; Delgado, Andres Ignacio; (Medina,
OH) ; Currie, William Dudley; (Stow, OH) |
Correspondence
Address: |
The Goodyear Tire & Rubber Company
Patent & Trademark Department - D/823
1144 East Market Street
Akron
OH
44316-0001
US
|
Family ID: |
33097963 |
Appl. No.: |
10/441471 |
Filed: |
May 20, 2003 |
Current U.S.
Class: |
156/129 ;
156/130; 156/406.2 |
Current CPC
Class: |
B29D 30/0661 20130101;
B29D 2030/105 20130101; B29D 30/242 20130101; B29D 2030/202
20130101; B29D 30/2607 20130101; B29D 30/12 20130101 |
Class at
Publication: |
156/129 ;
156/130; 156/406.2 |
International
Class: |
B29D 030/52; B29D
030/58 |
Claims
What is claimed is:
1. A method of building and transferring a tread or a tread belt
reinforcing assembly on a tire building drum, the method comprising
the steps of: applying at least one uncured tread component onto a
radially collapsible building drum; inserting the at least one
uncured tread component and the radially collapsible building drum
into an open segmented mold wherein a plurality of mold tread
forming segments are radially expanded; contracting the plurality
of mold tread forming segments pressing into the at least one
uncured tread component; collapsing the building drum; removing the
building drum thereby transferring the at least one uncured tread
component into the mold.
2. The method of claim 1 further comprises the steps of: inserting
a tire carcass into the mold; closing the mold; expanding the
carcass under pressure forcing the carcass into contact with the at
least one uncured tread component forming a tire assembly; curing
the tire assembly.
3. The method of claim 1 further comprises the step of: heating the
at least one uncured tread component to a temperature above ambient
prior to closing the segments and wherein the at least one uncured
tread component is warm and softened as the segments press into the
tread.
4. The method of claim 1 wherein the step of applying at least one
uncured tread component includes: applying one or more cord
reinforced belt, breaker, underlay or overlay layers onto the
building drum prior to applying one or more layers or strips of
uncured tread rubber to form a tread belt reinforcing assembly.
5. An apparatus for building and transferring a tread or tread belt
reinforcing assembly comprises: a radially expandable and axially
rotatable support means; a drive means for rotating the support
means about the axis; a plurality of arcuate or straight segments
slidably mounted over the support means, the plurality of arcuate
or straight segments forming an annular building surface; a
transfer means for removing the plurality of arcuate or straight
segments from the support means and wherein the transfer means
provides radial support for the plurality of arcuate or straight
segments when the support means is contracted.
6. The apparatus of claim 5 further comprises: a means for radially
expanding and contracting the radially expandable and axially
rotatable support means.
7. The apparatus of claim 6 further comprises: a means for
receiving and for accepting the tread or tread belt assembly while
mounted on the plurality of arcuate or straight segments mounted
onto the support means, the receiving means being a segmented mold
with radially movable tread forming segments.
8. An apparatus for building and transferring a tread or tread belt
reinforcing assembly comprises: a portable radially expandable and
axially rotatable support means; a drive means for rotating the
support means about the axis; a plurality of arcuate or straight
segments slidably mounted over the support means, the plurality of
arcuate or straight segments forming an annular building surface; a
means for radially expanding and contracting the radially
expandable and axially rotatable support means; a means for
receiving and accepting the tread or tread belt assembly while
mounted on the plurality of arcuate or straight segments mounted
onto the portable support means, the receiving means being a
segmented mold with radially movable tread forming segments.
9. The apparatus of claim 8 further comprises a plurality of
arcuate gap spanners interposed between each adjacent pair of
arcuate or straight segments and wherein each arcuate segment has a
gap of at least 0.050 (1.25 mm) in the radially expanded position,
the gap spanners providing a radially outer surface which bridges
between and overlaps pairs of adjacent segments.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a method and an apparatus for
building and transferring a tread or a tread belt reinforcing
structure on a building drum.
BACKGROUND OF THE INVENTION
[0002] In the manufacture of pneumatic tires elastomeric
components, some of which are reinforced by cords of textile or
wire, are formed as long strips. These strips are assembled
together to form a carcass subassembly in a first stage of
assembly. This carcass typically has one or more cord reinforced
plies, a pair of bead cores and an air impervious liner. Additional
strips of material such as apexes, shoulder gum strips and chippers
and chaffers may also be used in this first stage of tire
assembly.
[0003] In a second stage the tread rubber and belt or breaker
reinforcing structure is typically applied to the carcass after the
carcass has been toroidally shaped on the tire building drum. The
tread rubber can be of one homogeneous compound or more. Typically
the tread is a sophisticated composite of many different rubber
materials co-extruded to form a tread strip. The belt or breaker
reinforcing layers generally include two layers or more of cross
plies reinforced by equal but oppositely oriented cords of
textiles, such as nylon or aramid or wire such as steel.
Additionally, overlays or underlays of generally circumferentially
oriented cords may be added as an additional layer.
[0004] Tires typically have been built using this two-stage
assembly. Once assembled this uncured assembly of the components is
placed in a mold to be vulcanized to form a finished tire.
[0005] High speed and efficient ways to manufacture tires require
the processes to be reliable and fast. Accordingly, manufacturers
of tires have experimented with and perfected many ways to improve
on the basic two-stage assembly of tires.
[0006] One method described in U.S. Pat. No. 3,865,670 taught the
use of an expansible and contractible transfer ring for conveying a
breaker tread assembly from a building drum in a tire building
machine to a tire carcass mounted on a tire shaping machine.
[0007] An improved but somewhat similar U.S. Pat. No. 3,888,720
also disclosed a separate tread breaker building drum designed to
vary in size to accommodate different sizes of tires.
[0008] Similarly, the Charles E. Todd U.S. Pat. No. 3,865,669 also
disclosed an expansible and contractible transfer ring for
conveying a breaker-tread assembly.
[0009] Each of these prior art patents recognized that an assembly
of a tread belt to a tire carcass can be accomplished off-line or
separate from the carcass building machine. Once formed into a ring
these tread breaker assemblies could be moved to encircle a tire
carcass, the carcass inflated to contact the inner surface of the
tread breaker assembly and then stitched together by a roller
mechanism to form a green or uncured tire assembly to be placed
into a mold.
[0010] While these assembly techniques provided efficiencies in
production, none really changed the method for actually forming a
tire assembly.
[0011] Conventional tire molds, whether two piece molds or
segmented molds, form the tread surfaces by pressing groove forming
ribs and sipe forming blades into the tread rubber as the tire is
molded. As this is done the belt cords, particularly those directly
under the groove-forming ribs deflect in small but noticeable
undulations. These undulations create a variety of changes across
the tread that actually can vary the surface or change the amount
of tread rubber across the otherwise normal appearing tire. These
non-uniformities can lead to mass imbalance issues, irregular wear
and a variety of associated ride and handling performance issues.
The goal in tire manufacturing is to minimize unpredictable
non-uniformities in manufacturing while also building the tire in a
very cost-efficient manner.
[0012] The object of the present invention is to provide a method
that minimizes or eliminates the influence of the tread forming
mold surfaces as the tire is molded.
[0013] A further object of the invention is to provide a more
productive method of assembling the tread-belt or breaker
reinforcing structure to the carcass.
[0014] Another objective is to change the method of how the tread
forming surfaces engage the tread rubber.
[0015] Still another objective is to provide a novel apparatus for
forming the tread-belt or breaker assembly and to employ that
apparatus to a unique tire building system.
SUMMARY OF THE INVENTION
[0016] A method of building and transferring a tread on a tread
belt reinforcing assembly on a building drum is disclosed. The
steps include applying at least one uncured tread component onto a
radially collapsible building drum; inserting the at least one
uncured tread component and the radially collapsible building drum
into an open segmented mold wherein a plurality of tread forming
segments are radially expanded; contracting the plurality of tread
forming segments pressing into the at least one uncured tread
component; collapsing the building drum; and removing the building
drum thereby transferring the at least one uncured tread component
into the mold.
[0017] The method further includes inserting a tire carcass into
the mold; closing the mold; expanding the carcass under pressure
forcing the carcass into contact with the at least one uncured
tread component forming a tire assembly; and curing the
assembly.
[0018] Preferably, the method provides the additional step of
heating the at least one uncured tread component to a temperature
above ambient most preferably at 110.degree. C. or more, prior to
closing the segments and wherein the at least one uncured tread
component is warmed and softened as the segments press into the
tread.
[0019] The step of applying at least one uncured tread component
also can include applying one or more cord reinforced belt,
breaker, overlay or underlay layers onto the building drum prior to
applying one or more layers or strips of uncured tread rubber to
form a tread-belt reinforcing assembly.
[0020] The apparatus for building and transferring a tread or tread
belt reinforcing assembly has a radially expandable and axially
rotatable support means; a drive means for rotating the support
means about the axis; a plurality of arcuate or straight segments
slidably mounted over the support means, the plurality of arcuate
or straight segments forming an annular building surface; a
transfer means for removing the plurality of arcuate or straight
segments from the support means and wherein the transfer means
provides radial support for the plurality of arcuate or straight
segments when the support means is contracted.
[0021] The apparatus further includes a means for radially
expanding and contracting the radially expandable and axially
rotatable support means.
[0022] The preferred apparatus has a portable radially expandable
and axially rotatable support means; a drive means for rotating the
support means about the axis, a plurality of arcuate or straight
segments slidably mounted over the support means, the plurality of
arcuate or straight segments forming an annular building surface; a
means for radially expanding and contracting the radially
expandable and axially rotatable support means; a means for
receiving and accepting the tread or tread belt assembly while
mounted on the plurality of arcuate or straight segments mounted
onto the portable support means, the receiving means being a
segmented mold with radially movable tread forming segments.
[0023] The preferred apparatus further has a plurality of arcuate
or straight gap spanners interposed between an adjacent pair of
arcuate or straight segments and wherein each pair of adjacent
arcuate or straight segments has a gap of at least 0.050 in. (1.25
mm) in the radially expanded position, the gap spanners providing a
radially outer surface which bridges between and overlaps pairs of
adjacent segments. When radially contracted the arcuate or straight
segments reduce the circumferential gap and thereby
circumferentially reduce the length of the surface supporting the
tread or tread belt reinforcing assembly, thereby releasing the
tread or tread belt assembly.
[0024] The arcuate or straight segments and the overlapping gap
spanners when mounted on the support means and fully expanded
provide a rigid internal surface that prevents the tread or tread
belt assembly from locally distorting as the mold tread forming
segments are closed. Once closed the tread rubber is pressed into
the tread forming surface securing the tread or tread belt
reinforcing assembly. Once secured the arcuate or straight segments
of the support means are contracted releasing from the inner
surface of the tread or tread belt assembly. After contracting, the
entire portable support means with contracted arcuate or straight
segments can be removed from the mold while the mold's tread
forming segments are in a closed position holding the tread or
tread belt assembly. Then the uncured carcass can be placed into
the mold and the mold closed and the curing processes can be
initiated.
[0025] Definitions
[0026] "Apex" means an elastomeric filler located radially above
the bead and interposed between the plies and the ply turnup.
[0027] "Axial" and "axially" means the lines or directions that are
parallel to the axis of rotation of the tire.
[0028] "Bead" means that part of the tire comprising an annular
tensile member wrapped by ply cords and shaped, with or without
other reinforcement elements such as flippers, chippers, apexes,
toe guards and chafers, to fit the design rim.
[0029] "Breaker Structure" refers to at least two annular layers or
plies of parallel reinforcement cords oppositely oriented having
the same angle or about 5.degree. less than the parallel
reinforcing cords in carcass plies, generally about 20.degree. to
less than 50.degree. with reference to the equatorial plan of the
tire.
[0030] "Belt Structure" means at least two annular layers or plies
of parallel cords, woven or unwoven, underlying the tread,
unanchored to the bead, and having both left and right cord angles
in the range from 17.degree. to 27.degree. with respect to the
equatorial plane of the tire.
[0031] "Carcass" means an unvulcanized laminate of tire ply
material and other tire components cut to length suitable for
splicing, or already spliced, into a cylindrical or toroidal shape.
Additional components may be added to the carcass prior to its
being vulcanized to create the molded tire.
[0032] "Casing" means the carcass, the belt reinforcement and other
components of the tire excluding the tread.
[0033] "Chafers" refers to narrow strips of material placed around
the outside of the bead to protect cord plies from the rim,
distribute flexing above the rim, and to seal the tire.
[0034] "Circumferential" means lines or directions extending along
the perimeter of the surface of the annular tread perpendicular to
the axial direction.
[0035] "Cord" means one of the reinforcement filaments, cables, or
strands of which the plies in the tire are comprised.
[0036] "Equatorial plane (EP)" means the plane perpendicular to the
tire's axis of rotation and passing through the center of its
tread.
[0037] "Innerliner or liner" means the layer or layers of elastomer
or other material that form the inside surface of a tubeless tire
and that contain the inflating fluid within the tire.
[0038] "Overlay" means one or more layers of parallel cords
underlying tread above the belt structure and having cord angles
typically 0.degree. to 15.degree. with respect to the equatorial
plane of the tire.
[0039] "Ply" means a continuous layer of rubber-coated parallel
cords.
[0040] "Radial" and "radially" mean directions radially toward or
away from the axis of rotation of the tire.
[0041] "Radial ply tire" means a belted or
circumferentially-restricted pneumatic tire in which the ply cords
which extend from bead to bead are laid at cord angles between
65.degree.-90.degree. with respect to the equatorial plane of the
tire.
[0042] "Section height" means the radial distance from the nominal
rim diameter to the outer diameter of the tire at its equatorial
plane.
[0043] "Section width" means the maximum linear distance parallel
to the axis of the tire and between the exterior of its sidewalls
when and after it has been inflated at normal pressure for 24
hours, but unloaded, excluding elevations of the sidewalls due to
labeling, decoration or protective bands.
[0044] "Shoulder" means the upper portion of sidewall just below
the tread edge.
[0045] "Shoulder gum strip" means an elastomeric reinforcement
located in the shoulder region of the carcass.
[0046] "Sidewall" means that elastomeric portion of a tire between
the tread and the bead.
[0047] "Subassembly" means an unvulcanized assembly of laminated
unreinforced tire components to which a cord reinforced ply or
plies and other tire components can be added to form a casing.
[0048] "Tread" means a rubber component which when bonded to a tire
carcass includes that portion of the tire that come into contact
with the road when the tire is normally inflated and under normal
load.
[0049] "Tread width" means the arc length of the tread surface in
the axial direction, that is, in a plane parallel to the axis of
rotation of the tire.
[0050] "Underlay" means one or more layers of parallel cords
underlying the belt structure or at least one layer of the belt
structure and having cord angles typically 0.degree. to 15.degree.
with respect to the equatorial plane of the tire.
BRIEF DESCRIPTION OF THE DRAWINGS
[0051] The invention will be described by way of example and with
reference to the accompanying drawings in which:
[0052] FIG. 1 is a perspective view of the tread or tread belt
assembly building drum of the present invention;
[0053] FIG. 2 is a cross-sectional view of the tread or tread belt
assembly building drum of the present invention;
[0054] FIG. 3 is a perspective view of the transfer means engaged
in the support means of the building drum;
[0055] FIG. 4 is a cross-sectional view of the apparatus taken from
FIG. 3;
[0056] FIG. 5 is a perspective view showing the transfer means with
the support means attached thereto and separated from the building
drum;
[0057] FIG. 6 is a cross sectional view of the apparatus taken from
FIG. 5;
[0058] FIG. 7 is a cross-sectional view of the tread or tread belt
assembly building drum attached to the drive means for rotating the
drum and illustrating the means for radially expanding and
contracting the support means as well as an overload clutch
means;
[0059] FIG. 8A is a cross-sectional view of the adjacent arcuate or
straight segments with a gap spanner shown in the expanded fully
open position;
[0060] FIG. 8B is the same features illustrated in FIG. 8A but in
the fully collapsed contracted position;
[0061] FIG. 9 is a perspective view of the building drum assembly
showing a tread belt assembly as applied to the support
surface;
[0062] FIG. 10 is a cross-sectional view of the tread or tread belt
assembly mounted on the building drum and being placed into an
opened mold;
[0063] FIG. 11A is a cross-sectional view of the tread or tread
belt assembly mounted on the building drum with the mold being
closed onto the assembly;
[0064] FIG. 11B is a cross-sectional view of the tread belt
assembly in the mold with the building drum collapsed and being
removed from the mold; and
[0065] FIG. 12 is a cross-sectional view of the mold and tread or
tread belt assembly being cured to a carcass assembly mounted on a
collapsible building drum assembly.
DETAILED DESCRIPTION OF THE INVENTION
[0066] With reference to FIG. 1, a perspective view of the tread or
tread belt assembly building drum of the present invention is
illustrated. As shown, the building drum 10 has a radially
expandable and contractible support means 20. The support means 20
has a radially outer surface 24 for building a tread or tread belt
reinforcing structure onto the surface 24. The surface has a
plurality of arcuate or straight segments 22 which are connected by
gap spanner segments 21 around the peripheral surface of the tread
building support means. The arcuate or straight segments 22 and gap
spanner segments 21 are slidably attached onto the building drum
support means 20. Each arcuate segment 22 has a hole or opening 55
for accepting a plurality of pins located on a transfer means 50.
The pins 54 can be pressed into the openings 55 and provide a means
50 for transferring the arcuate or straight segments and gap
spanner segments as an assembly onto and off the support means
20.
[0067] As used herein, each segment 22 and gap spanner segment 21
can have a flat or straight circumferentially or laterally
extending surface or, alternatively, an arcuate surface.
Hereinafter the segments will be generally referred to as arcuate
while it is understood the surface may be straight in either the
circumferential direction or the lateral direction.
[0068] As illustrated, in FIG. 1 the transfer means 50 has an
annular transfer ring 51 and a guide ring 52. The guide ring 52 is
slidably inserted over the pins 54 and the pins 54 are rigidly
attached to the transfer ring 51 as shown. On the exterior surface
of the transfer means 50 are shown three knobs 53.
[0069] With reference to FIG. 2, a cross sectional view of the
building drum 10 is shown along with the transfer means 50. The
transfer means 50 is shown not engaged to the building drum 10 or
to the arcuate or straight segments 22. The combination of the
arcuate or straight segments 22 and the gap spanner segments 21
form a subassembly commonly referred to as the deck. The term
"deck" is commonly referred to with a similar meaning as that of
the deck of a boat. It is an exterior surface upon which one can
stand or build the tread assembly. For purposes of this invention
the building surface 24 will commonly be referred to as the deck
24. This deck 24 which is an assembly of the arcuate or straight
segments 22 and the gap spanning segments 21 is slidably mounted
over deck segment guides 116 and 117. Once slid over these guides
116, 117 a detent assembly called a deck segment locking pin 115
engages and secures the deck 24 to the drum expansion segment 114
as illustrated. To remove the deck assembly 24 from the radially
expandable and contractible tread building drum, the transfer means
50 is pushed into the holes 55 wherein the pins 54 engage the deck
segment locking pins 115 thereby releasing them when the pins 54
are fully engaged. This is illustrated in FIGS. 3 and 4. Once
engaged the transfer means 50 can be used to slidably remove the
deck assembly 24 as shown in FIG. 5. The pins 54 provide radial
support for the deck assembly 24 and hold the assembly 24 in the
position as shown for removal. The perspective view of the removed
deck assembly 24 provides a better illustration of the deck segment
guides 116 and 117 and the drum expansion segment 114. As shown,
the arcuate or straight segments 22 have the deck segment locking
pin 115 engaged by the pin 54. A spring 129 is used in the
contracted position when the pin 54 is inserted as shown in FIG. 6.
Once the pin 54 is removed the spring 129 is free to release and
allow the locking pin 115 to extend radially inwardly to accomplish
the locking of the mechanism. This is as illustrated in the
cross-sectional view of FIG. 6.
[0070] In order for the tread belt building drum 10 to expand
radially and contract radially and to provide a surface 24 upon
which a tread belt assembly can be built, the building drum 10 must
accept a drive means 30 that provides rotational movement of the
entire building drum assembly 10 as shown in FIG. 7. The drive
means 30 is connected to a motor (not illustrated) which can
provide rotational movement of the tire building drum assembly 10.
The drive means 30 includes a drive spline 100 which is connected
to a screw drive shaft 101 and which is embedded inside a drum
quick-mount mounting cone 102 as illustrated. The quick-mount
mounting cone 102 provides for rapid engagement and disengagement
of the drum assembly 10. The drum quick-mount mounting cone 102 has
a key 104 with a key locating pin 103 as illustrated and a
longitudinally extending keyway 105 as illustrated. A drum inboard
housing 106 is illustrated on the left-hand side of FIG. 7 and a
corresponding drum outboard housing 107 is on the right-hand side
of FIG. 7. On the opposite side of the drive means 20 and the drum
assembly 10 is an outboard support cone 108. The outboard support
cone 108 has a live center receptacle 109. The live center permits
easy rotation of the drum assembly 10 while the entire assembly is
being rotated. Looking internally at the center of the mechanism or
apparatus 10 there is a ball screw or acme threaded screw assembly
110. As illustrated the threaded assembly 110 is comprised of two
components, one having left-hand threads and an opposite side
having right-hand threads. These two components are pinned together
to provide simultaneous rotation of the mechanism. On the left-hand
side is an inboard ball nut or acme nut 111 connected to one end of
the threaded screw 110 and on the opposite or outboard side another
ball nut or acme nut 112 is illustrated. A ball screw overload
protection clutch mechanism is illustrated at 113. This mechanism
113 provides capability of disengaging the shaft 110 and permitting
the drum assembly 10 to collapse if the pressure is exceeded beyond
the capability of the clutch 113. This override clutch protection
system 113 ensures that when the mold closes or pressure is applied
to the radially outer surface of the deck 24, the deck 24 can
collapse as the clutch 113 disengages, permitting the entire unit
or drum 10 to collapse slightly preventing any overload from
damaging the internal workings of either the mold or the mechanism
10. Radially directly inward of the deck 24 or its arcuate or
straight segments 22 there is illustrated a drum expansion segment
114. The drum expansion segments 114 are threadedly engaged by
threaded fasteners 125 to an expanding segment base 123 as
illustrated. They are also located by pins 122 as shown. Radially
inward of the expanding segment base 114 is an outward outboard
segment cone bushing 121 and an inboard segment cone bushing 120
which are threadedly attached using screws or threaded fasteners
126 as illustrated to the expanding segment base 123. Radially
inward of the inboard segment bushing 120 is the inboard expansion
cone 118. Similarly, on the outboard side the outboard segment cone
bushing 121 is radially outward of an outboard expansion cone 119.
The bushings 120 and 121 are designed to slide along the cone
surfaces of the inboard expansion cone 118 and outboard expansion
cone 119, respectively. As shown, the building drum 10 is in an
expanded position such that the radially outer deck or building
surface 24 is radially expanded. As the drive shaft 101 is spun or
rotated inside the bearings 127, 128 the inboard ball nut 111 and
outboard ball nut 112 push the expansion cones both inboard and
outboard 118 and 119, respectively, radially to the center plane of
the building drum 10. As these cones 118, 119 push to the center
plane, the conical surface permits the expanding segment base 123
and its bushings 120 and 119 to slide along the conical surfaces
and contract radially inwardly.
[0071] With reference to FIG. 8A in the fully expanded position the
arcuate or straight segments 22 are shown with a gap G between each
segment in the fully radially expanded position. The gap G is
preferably at least 0.050 in (1.25 mm) as measured between the
adjacent segments. The gap spanning segment 21 is constrained in
channels 25. Each gap spanning segment 21 has lobes 26 that are
captured within these channels 25. They may be slid laterally to
remove the segments 21, 22 but are constrained such that the
arcuate or straight segments 22 can move circumferentially a
certain extent until they engage the lobes 26 as illustrated. This
permits a diametrical expansion of the assembly 10 by a few
millimeters. The ends of the segments 22 have a chamfered surface
27 which provides a space for the gap spanning segment to occupy at
the correct diameter for tread belt building. Upon contraction, as
shown in FIG. 8B, the arcuate or straight segments close upon each
other and the gap spanning segments 21 are moved within the
channels 25 such that the lobes 26 contact the interior surface of
the arcuate or straight segments as illustrated in FIG. 8B. When
this occurs the gap G between the adjacent arcuate or straight
segments 22 is closed permitting each of the segments 22 to
contract radially inwardly. This feature enables one to build a
tread or tread belt assembly in such a manner that the tread or
tread belt assembly can easily be removed once assembled to the
deck assembly 24. This will be discussed later in detail.
[0072] With reference to FIG. 9, the tread drum assembly 10 is
shown wherein a typical tread belt reinforcing structure 14 is
shown assembled to the exterior surface or peripheral surface of
the deck 24. As shown, a first belt layer 16 is illustrated lying
adjacent to the surface 24. At the lateral edges of the first belt
layer 16 are two belt edge elastomeric strips 17. Interposed in
between the elastomeric strips 17 is a second belt layer 15 having
cords oriented oppositely relative to the first belt layer 16.
Optionally, and as illustrated, an overlay 18 is shown. The overlay
18 is a circumferentially extended cord reinforced structure that
overlays both the second belt layer 15 and the first belt layer 16
and the underlying gum strips 17. Radially outward of the overlay
18 is an unvulcanized layer 12 of tread rubber. As illustrated the
tread rubber 12 may be provided as strips of rubber wound and laid
adjacently or can be provided as a single layer.
[0073] With reference to FIG. 10, once the tread belt assembly 14
is applied onto the building surface 24, the entire building drum
assembly can be placed inside a mold 2. In the illustrated
embodiment, the tread assembly 14 is shown mounted on a building
drum 10 that is in a radially expanded position and placed inside
the open and expanded mold 2. The mold 2 has tread forming segments
4 on each side, a bottom plate 6, a pair of bead forming rings 11
and 9, a top plate 8, and a tread forming segment 5 attached to the
top plate 8. Once inserted inside the mold 2, as shown in FIG. 11A,
the mold 2 is closed and in the particular embodiment illustrated
the mold segments contract against the tread belt assembly on the
tread belt drum assembly 10. In this methodology the tread rubber
12 is then forced into the tread forming grooves of the segments 4.
Once fully contracted the tread rubber 12 would adhere to the tread
forming segments 4. As illustrated it is preferred that the tread
rubber 12 be warmed or applied to the building drum 10 hot, such
that when the mold closed, the rubber is relatively softened so
that it will easily accept, adapt and conform to the tread forming
segments 4. It is believed that the tread 12 should be warmed to a
temperature of approximately 110.degree. C., preferably between
90.degree. C. and 110.degree. C. Once the pressure is applied as
shown, assuming the pressure does not exceed the desired limits,
the entire tread belt assembly 14 will be adequately adhered to the
internal surfaces of the tread forming segments 4. While the mold 2
is still closed, it is desirable then to contract the tread belt
drum assembly 10 into a radially contracted position. The tread
belt 14 will remain in the tread forming segments 4. Once fully
retracted the drum 10 is freed from the tread belt assembly 14 and
the top plate of the mold 8 can be removed along with the
associated connected components as was illustrated in FIG. 10. Once
the mold top plate 8 is removed, the tread drum assembly 10 can be
removed from the mold 2. Once removed the tread belt 14 is left in
the mold 2 with the segments 4 closed and a tire building drum
assembly 7 with a green carcass 72 already mounted to it can be
placed into the mold 2. As shown in FIG. 12 the carcass building
drum assembly 7 has an axle 70 that is contoured and locked into
the mold using locking detents 74. Once closed a gaseous fluid or
steam is introduced into the interior through the axle 70 and the
internal pressure is applied to the carcass adhering it to the
tread belt assembly at the interfacial surfaces. The tire is then
cured in this self-locking mold 2 as illustrated in FIG. 12.
[0074] When a mold 2 is first closed and the tread building drum
assembly 10 is inside the mold, should the mold be misaligned or
the tread rubber 12 not properly aligned for closing the segments
4, then the clutch mechanism 113 will disengage allowing the entire
assembly 10 to collapse, thereby preventing damage to the mold 2 as
previously discussed.
[0075] The present invention permits the assembly of the tread belt
assembly 14 to be made on the building drum 10 and as illustrated
and the building drum 10 being portably movable permits the entire
assembly to be placed inside a mold whereby the tread belt assembly
14 can be transferred directly to the mold 2 prior to being applied
to the carcass 72. Then the tread building drum assembly 10 can be
collapsed and removed from the mold 2 and the entire green carcass
72 on a building drum assembly 7 can be inserted into the mold 2,
locked into position, pressurized and cured to form a finished
tire.
[0076] This method for molding tires is described in a self-locking
and copending patent application entitled "The Method For Curing
Tires and a Self-Locking Tire Mold", U.S. Pat. Ser. No. 10/417,849,
filed on Apr. 17, 2003, which is incorporated herein by reference
in its entirety. The core building drum assembly 7 for mounting the
carcass directly onto is described in U.S. patent application Ser.
No. 10/388,733, filed Mar. 14, 2003 and is entitled "Radially
Expansible Tire Assembly Drum and Method for Forming Tires", the
contents of which are incorporated herein by reference in its
entirety also.
[0077] In an alternative method of practicing the invention, the
tread 12 or tread belt assembly 14 can be applied to the deck 24
when the deck 24 is set at an outside diameter less than the
diameter required to fit precisely in the closed mold position.
Typically a small amount of at least 0.5 mm less than the desired
finish diameter of the tread belt 14 is selected. In this method of
assembly, once the tread 12 or tread belt assembly 14 is placed in
the open mold 2 and after the mold 2 is closed and the mold
segments 4 are contracted embedding into the tread rubber 12, then
the drive means 30 can be rotated, expanding the building drum 10
from the slightly smaller build diameter to the precise mold
diameter required. This additional expansion firmly compresses the
tread 12 or tread belt assembly 14 into the mold tread forming
segments 4 and insures a slight tensioning of the tread 12 or tread
belt assembly 14 into the mold tread forming segments 4 and insures
a slight tensioning of the tread 12 or tread belt assembly 14. Then
the deck 24 can be retracted releasing it from the tread 12 or
tread belt assembly 14 as previously discussed.
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