Method for manufacturing carcass plies for a tire

Abstract

A method of manufacturing an annular toroidially-shaped cord reinforced ply for a tire is described. The method involves applying an elastomeric layer on a toroidal surface and placing and stitching one or more cords in continuous lengths onto the elastomeric layer in predetermined cord paths. The method further includes dispensing the one or more cords from spools and guiding the cord in a predetermined path as the cord is being dispensed. Preferably, each cord is held against the elastomeric layer after the cord is placed and stitched and then indexing the cord path to a next circumferential location forming a loop end by reversing the direction of the cord and releasing the held cord after the loop end is formed and the cord path direction is reversed. This method allows the step of forming loop ends to occur at more than one diameter on the toroidal surface. In one embodiment the toroidal surface has a first concave curvature, a convex crown and a second concave curvature and the step of placing and stitching each cord includes traversing the cord across a path including at least one of the first or second concave curvatures and at least a portion of the convex crown.

Description

FIELD OF THE INVENTION

This invention relates to an improved method for manufacturing a toroidal carcass ply for a tire.

BACKGROUND OF THE INVENTION

Historically, the pneumatic tire has been fabricated as a laminate structure of generally toroidal shape having beads, a tread, belt reinforcement, and a carcass. The tire is made of rubber, fabric, and steel. The manufacturing technologies employed for the most part involved assembling the many tire components from flat strips or sheets of material. Each component is placed on a building drum and cut to length such that the ends of the component meet or overlap creating a splice.

In the first stage of assembly the prior art carcass will normally include one or more plies, and a pair of sidewalls, a pair of apexes, an innerliner (for a tubeless tire), a pair of chafers and perhaps a pair of gum shoulder strips. Annular bead cores can be added during this first stage of tire building and the plies can be turned around the bead cores to form the ply turnups. Additional components may be used or even replace some of those mentioned above.

This intermediate article of manufacture would be cylindrically formed at this point in the first stage of assembly. The cylindrical carcass is then expanded into a toroidal shape after completion of the first stage of tire building. Reinforcing belts in the tread are added to this intermediate article during a second stage of tire manufacture, which can occur using the same building drum or work station.

This form of manufacturing a tire from flat components that are then formed toroidially limits the ability of the tire to be produced in a most uniform fashion.

In U.S. Pat. No. 3,935,894, issued Feb. 3, 1976, Jacques Pouilloux indicated that carcass plies could be laid in hoops or arcs having the ends of the carcass cord plies extending in a circumferential direction. It was his objective that a tire made this way could be dispensed of any circular bead core in the beads and the carcass would not have any lateral parts turned up radially with the edges delimited by cut cables. While this tire was not commercially viable in its time, new inventions have been described also constructing the ply using hoops of circular arcs so that the individual ply cords are laid across the convex toroidal cross section in its early stage of manufacture as opposed to being made in the flat construction. Such a concept is used by Michelin in a process called C3M wherein the cords extend in linear paths across the carcass. Early versions of the C3M process included wrapping the ply cords around bead cores to effect a change in cord direction. These ply cords were always placed in tension around a circular arcuate shape in the course of manufacture. Later versions of the C3M process included turning these linear extending cords in an opposite direction and sandwiching these cords between radially extending bead layers.

A similar process is described in EP0897813 A2 and is assigned to the Bridgestone Corporation. In EP0897813 one of the primary objectives is to simultaneously produce multiple arches using multiple cords in the process of manufacturing the carcass ply in the hopes of speeding up the rate of manufacture. The prior art tires to that date were produced in a method wherein each of the circumferential portions is made from a single fine cord and the distance between cords or the pitch C is very narrow. Therefore, it was an object of this European patent to teach a method of manufacturing a pneumatic tire wherein an array of cords were used so that the pitch between cords could be increased as the array is being applied.

In all these methods of manufacturing ply cords on a toroidal surface it has been determined that a tension was required and that the cords must be laid in a straight line on a convex surface from turnaround to turnaround. In other words, the cord angle could be arranged other than 90°, however, 90° is a preferred way in the prior art of orienting the cord path because 90° prevents any likelihood of slippage off angle because 90° is the shortest ply path. These angles could not be adjusted in any fashion other than to provide a linear path. This is true because the tension placed on the cord during the manufacture was required as the cord is being applied on the round or convex surface. In each step, the known prior art methods of manufacturing such a carcass ply uses a technique called “winding” wherein the turnarounds applied tension across the entire ply path. Such a tire winding procedure to apply ply cords can only work on a convex 60 surface and does not allow “placement” on a toroidal shape having a concavity as is common in the true manufacture of the molded tire in the sidewall regions near the beads.

It is an object of the present invention to provide a method of manufacturing ply cords that can allow placement on concave and convex surfaces more similar to the finished tire. It a further object of the present invention not to require tension from turnaround to turnaround as the cord path is being established thereby permitting nonlinear cord paths to be achieved. It is a further object of the present invention to allow the cord loop endings or turnarounds to occur at different diameters. There is still a further object of the invention that the placement of the ply cords can be such that toroidially shaped ply cords can be placed that would further include forming turnups and allow for anchoring the ply using the bead cores. Furthermore, another object of the invention is to have the pitch between the cords uniformly increase as the diameter increases along the cord path. Preferably, the cord pitch increases uniformly as the diameter increases along the ply path due to a coordinated differential motion between the application of the cord and the movement of the toroidal surface. These objects, alone or in various combinations, may be realized by the invention. Further objects, advantages and/or features may also be achieved in accordance with the invention.

SUMMARY OF THE INVENTION

A method of manufacturing an annular toroidially-shaped cord reinforced ply for a tire is described. The method involves applying an elastomeric layer on a toroidal surface and placing and stitching one or more cords in continuous lengths onto the elastomeric layer in predetermined cord paths. The method further includes dispensing the one or more cords from spools and guiding the cord in a predetermined path as the cord is being dispensed. Preferably, each cord is held against the elastomeric layer after the cord is placed and stitched and then the cord path is indexed to a next circumferential location forming a loop end by reversing the direction of the cord and releasing the held cord after the loop end is formed and the cord path direction is reversed. This method allows the step of forming loop ends to occur at more than one diameter on the toroidal surface. In one embodiment the toroidal surface has a first concave curvature, a convex crown and a second concave curvature and the step of placing and stitching each cord includes traversing the cord across a path including at least one of the first or second concave curvatures and at least a portion of the convex crown.

Preferably, the indexing of the toroidal surface establishes the cord pitch uniformly in discrete angular spacing at specific diameters.

The method as described above permits the forming of ply turnups by extending the elastomeric loops and the loop ends on each side of the toroidal surface.

The above-method permits an unusual number of ply cord paths to be taken in rather unique patterns. In one embodiment, the forming of loop ends includes locating one loop end at a radially inner diameter, one or more adjacent loop ends at radially outer diameters in a repeating pattern on each side of the toroidially shaped elastomeric surface. The loop ends can be varied in location such that a plurality of loop ends can occur at a first radially inner diameter d_i and a plurality of other loop ends at one or more radially outer larger diameters d_o, d_o being greater than d_i, thereby forming ply paths having varying amounts of cord pitch at different locations on the toroidal surface.

The above method may be performed using an apparatus for forming an annular toroidially shaped cord reinforced ply which has a toroidal mandrel, a means to dispense one or more cords, a means to guide the dispensed cords along predetermined paths, a means to place an elastomeric layer on the toroidal mandrel, a means to stitch the cords onto the elastomeric layer, and a means to hold the cords while loop ends are formed.

The toroidal mandrel is preferably rotatable about its axis and a means for rotating is provided which permits the mandrel to index circumferentially as the cord is placed in a predetermined cord path. The guide means preferably includes a multi axis robotic computer controlled system and a ply mechanism to permit the cord path to follow the contour of the mandrel including the concave and convex profiles.

Pursuant to another aspect of the invention, a method of manufacturing an annular toroidally shaped cord reinforced ply for a tire includes applying an elastomeric layer on a toroidal surface, the toroidal surface having opposite sides adjoining a toroidal surface equatorial plane, each side having a radially inward first region, a concave curvature disposed radially outward of the first region, a sidewall region disposed radially outward of the concave curvature and the sidewall region extending to a toroidal surface convex crown. The method further includes placing and embedding one or more cords in continuous lengths onto the elastomeric layer in predetermined relatively longer and shorter cord paths, the longer cord paths extending from a respective side of the toroidal surface over the convex crown of the toroidal surface and one or more relatively shorter cord paths having opposite path ends located within a sidewall region or the convex crown of the toroidal surface.

DEFINITIONS

“Aspect Ratio” means the ratio of a tire's section height to its section width.

“Axial” and “axially” means the lines or directions that are parallel to the axis of rotation of the tire.

“Bead” or “Bead Core” means generally that part of the tire comprising an annular tensile member, the radially inner beads are associated with holding the tire to the rim being wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes or fillers, toe guards and chaffers.

“Belt Structure” or “Reinforcing Belts” 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° to 27° with respect to the equatorial plane of the tire.

“Circumferential” means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction.

“Carcass” means the tire structure apart from the belt structure, tread, undertread, over the plies, but including beads, if used, on any alternative rim attachment.

“Casing” means the carcass, belt structure, beads, sidewalls and all other components of the tire excepting the tread and undertread.

“Chaffers” 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.

“Cord” means one of the reinforcement strands of which the plies in the tire are comprised.

“Equatorial Plane (EP)” means the plane perpendicular to the tire's axis of rotation and passing through the center of its tread.

“Footprint” means the contact patch or area of contact of the tire tread with a flat surface at zero speed and under normal load and pressure.

“Innerliner” 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.

“Normal Inflation Pressure” means the specific design inflation pressure and load assigned by the appropriate standards organization for the service condition for the tire.

“Normal Load” means the specific design inflation pressure and load assigned by the appropriate standards organization for the service condition for the tire.

“Placement” means positioning a cord on a surface by means of applying pressure to adhere the cord at the location of placement along the desired ply path.

“Ply” means a layer of rubber-coated parallel cords.

“Radial” and “radially” mean directions radially toward or away from the axis of rotation of the tire.

“Radial Ply Tire” means a belted or circumferentially-restricted pneumatic tire in which at least one ply has cords which extend from bead to bead are laid at cord angles between 65° and 90° with respect to the equatorial plane of the tire.

“Section Height” means the radial distance from the nominal rim diameter to the outer diameter of the tire at its equatorial plane

“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.

“Shoulder” means the upper portion of sidewall just below the tread edge.

“Sidewall” means that portion of a tire between the tread and the bead.

“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.

“Winding” means a wrapping of a cord under tension onto a convex surface along a linear path.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described by way of example and with reference to the accompanying drawings in which:

FIG. 1 shows a perspective view of the apparatus of the present invention;

FIGS. 2 and 3 illustrate cross-sectional views of the toroidal mandrel of the present invention;

FIGS. 4 through 9 show a simplified schematic view of a single cord being placed in a predetermined cord path in a flat view for ease of understanding;

FIGS. 10 through 15 show a simplified view of the cords as they are applied on the toroidal mandrel;

FIG. 16 shows a simplified schematic for dispensing a plurality of cords simultaneously;

FIG. 17 is a partial side view of an exemplary cord path;

FIG. 18 is a partial flat view of the exemplary cord path of FIG. 14 showing both sides of the ply path;

FIGS. 19 through 25 show a variety of exemplary ply path designs;

FIG. 26 illustrates cross-sectional views of the toroidal mandrel of the present invention having alternative cord path placement thereon.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

With reference to FIG. 1, a perspective view of an apparatus 100 in accordance with the present invention is illustrated. As shown the apparatus 100 has a guide means which has, in addition to the ply mechanism 70, a robotic computer controlled system 110 for placing the cord 2 onto the toroidal surface 50. A means for applying an elastomeric layer 4 onto the mandrel 52 is provided which can include a server mechanism (not shown) to feed strips of the layer 4 to the mandrel 52.

The robotic computer controlled system 110 has a computer 120 and preprogrammed software which dictates the ply path 10 to be used for a particular tire size. Each movement of the system 110 can be articulated with very precise movements.

The robot 150 which is mounted on a pedestal 151 has a robotic arm 152 which can be moved in preferably six axes. The manipulating arm 152 has the ply mechanism 70 attached as shown.

Loop end forming mechanisms 60 are positioned on each side 56 of the toroidal mandrel 52. The robotic arm 152 feeds the ply cord 2 in predetermined paths 10 and the loop end forming mechanism 60 holds the cord 2 in place as a looped end 12 is formed. Each time an end 12 is formed the toroidal mandrel 52 is rotated to index to the next pitch P and the adjacent ply path 10 around the toroidal mandrel 52.

The movement of the ply mechanism 70 permits convex curvatures to be coupled to concave curvatures near the bead areas thus mimicking the as molded shape of the tire. A means 63 for rotating the mandrel 52 about its axle 64 are all mounted to a rigid frame 65 as shown.

With reference to FIGS. 2 and 3, a cross-sectional view of the toroidal mandrel 52 of the present invention is shown. As illustrated the radially inner portions 54 on each side 56 of the toroidal mandrel 52 have a concave curvature that extends radially outward toward the crown area 55 of the toroidal mandrel 52. As the concave cross section extends radially outward toward the upper sidewall portion 57 the curvature transitions to a convex curvature in what is otherwise known as the crown area 55 of the toroidal mandrel 52. This cross section very closely duplicates the as molded cross section of a tire.

With reference to FIGS. 4 through 9, the means for guiding the dispensed cords has a ply mechanism 70 as shown in a schematic form which illustrates how the ply cord 2 is laid onto an elastomeric surface 4 in a predetermined ply path 10. The schematic views simply illustrate the basic working components of the ply mechanism 70 and give a very good illustration of how the mechanism 70 works to place the cords 2 in a very precise location.

To advance the cords 2 on a specified path 10, the mechanism 70 which contains two pairs of parallel pins or rollers 40, 42 with the second pair 42 placed 90° relative to the first pair 40 and in a physical space of about one inch above the first pair 40 and forms a center opening 30 between the two pairs of rollers which enables the cord path 10 to be maintained in this center. As illustrated, the cords 2 are held in place by a combination of embedding the cord into the elastomeric compound 4 previously placed onto the toroidal surface 50 and the surface tackiness of the uncured compound. Once the cords 2 are properly applied around the entire circumference of the toroidal surface 50 a subsequent lamination of elastomeric topcoat compound (not shown) can be used to complete the construction of the ply 20. As illustrated, the bottom pair of rollers 40 uses a first roller 40A to embed the cord 2 on a forward traverse across the toroidal surface 50 as illustrated in FIG. 4. In FIG. 5 once the cord path 10 has been transferred across the toroidal surface 50 the mechanism 100 stops and the holding mechanism and loop forming plate mechanism 60 advances onto the cord 2 and presses the cord 2 against the toroidal surface 50 as illustrated in FIG. 6. The mechanism 100 then reverses its path 10 forming a loop 12 in the ply cord path 10. At this point the second roller 40B of the first pair 40 pulls the cord 2 back across the toroidal surface 50. The top second pair 42 positions the cord 2 in a parallel path 10 and creates the spacing between the cords 2 hereinafter referred to as the pitch when the mandrel 52 having the toroidal surface 50 covered by the bottom coat compound laminate 4 advances for the return path. In other words, and as shown in FIG. 7 of the preferred embodiment, the toroidal surface 50 is indexed or advanced slightly allowing a circumferential spacing or pitch (P) to occur between the first ply pathway down in the second return ply path. As illustrated in FIG. 7, the loop 12 that is formed on the reverse traverse is slightly shifted and therefore allowed to be pulled against the loop forming mechanism 60 as the cord 2 clinches against the pin to create the desired loop position. As shown in FIG. 8, a looped end 12 is formed and the second ply path 10 is laid on the toroidal surface 50 parallel to the first ply path 10. As shown in FIG. 9, the loop mechanism 60 then retracts and the second ply path 10 is finished. This process is repeated to form a series of cords 2 that are continuous and parallel within at least certain portions of the ply path 10. This is accomplished by having toroidal mandrel 52 with the toroidal surface 50 with an elastomeric compound 4 laminated onto it to index or advance uniformly about its axis with each traverse of the pair of rollers pins 40, 42 to create a linearly parallel path 10 uniformly distributed about the toroidal surface 50. By varying the advance of the cord 2 as the mechanism 100 traverses, it is possible to create non-linear parallel cord paths 10 to tune tire stiffness and to vary flexure with the load.

Preferably, the cord 2 is wrapped around a tension or ply mechanism 70 to adjust and maintain the required tension in the cord 2. If it is too tight it will lift the cord from the coat laminate when the roller pins 40, 42 reverse direction. If it is too loose it will not create a loop at the correct length around the loop pin mechanism 60. As an example, tension on the cord 2 is created as it passes between a series of rollers 72 capable of adjusting and maintaining tension as needed for the process and the roller 40, 42. What is different about the present technique is that the amount of tension applied has to be sufficiently small that it does not lift the cords 2 from their placed position on the toroidal surface 50. In other words, the cord 2 is resting on the toroidal surface 50 positioned and stitched to an elastomeric layer 4 such that the tack between the cord 2 and the elastomeric layer 4 is larger than the tension applied by the ply mechanism 70. This permits the cords 2 to lay freely onto the toroidal surface 50 without moving or separating during the ply construction period. This is significantly different from the prior art mechanisms which required linear paths and required a large amount of tension to hold the cord paths 10 as the equipment is traversing over a convex surface to create a laminated ply.

With reference to FIGS. 10-15, attention is drawn to the three dimensional view of a cylinder representing how the ply path 10 is initiated along what would generally be considered the bead region 22 of the carcass 20 along the tire sidewall 24 toward the shoulder region 25 of the toroidal surface 50 and then traverses across the toroidal surface 50 in an area commonly referred to as the crown 26 as illustrated in FIG. 11. In FIG. 11 it will be noticed that the ply cord path 10 is laid at a slight angle. While the ply path 10 may be at any angle including radially at 90° or less, the ply path 10 also can be applied in a non-linear fashion. As shown in FIG. 12, once the ply cord 2 is traversed completely across the toroidal surface 50 and down the opposite side the loop 12 is formed as previously discussed and the cord 2 is brought back across the crown 26 as shown in FIG. 12. In FIG. 13 the cord 2 then proceeds down the tire sidewall 24 towards the bead region 22 where it is turned forming a loop 12 as previously discussed and then traverses back across the toroidal surface 50 in a linear path 10 as illustrated that is parallel to the first and second ply cord paths 10. This process is repeated in FIGS. 14 and 15 as the toroidal surface 50 is indexed, creating a very uniform and evenly spaced ply cord path 10.

With reference to FIG. 16, the ply mechanism 70 can be provided with additional rollers 40 such that multiple paths 10 can be traversed around the toroidal surface 50. As illustrated three dispensing spools 74 are shown traversing three rollers 42A, 42B, 42C that are spaced in a staggered sequence permitting the openings between each pair of rollers to continue to guide the cords 2 while the lower or bottom pair of rollers 40A, 40B provide the stitching of the cords 2 to the toroidal surface 50. Again the same loop mechanism 60 can be used for clinching the cords 2 at each loop end 12. As illustrated only one loop mechanism 60 is shown. However, it is understood that there would be a pair of loop mechanisms, one being on each side of the toroidal surface 50.

With reference to FIG. 17, a ply path 10 is shown whereby the loop ends 12B can be adjusted radially outwardly. As illustrated, the loop 12, while being part of a continuous strand of cord 2, is only partially shown going up to the sidewall 26 and terminating there. This continuous strand of cord 2 would create a path 10 whereby the loop ends 12B of the first set of adjacent pairs of cord paths 10 has loop ends 12B at a diameter slightly higher than the second pair of loop ends 12A. This is repeated in an alternating fashion. This particular cord path 10 creates the cord path 10 as illustrated in FIG. 18 shown in a lay flat position. The advantage of this type of cord path 10 is that fewer cord ends 12A are spaced at the bead attachment area 22 while in the crown area 26 additional ply cord paths 10 are added. It should be noted that depending on the ply cord diameter, the ends per inch are physically limited by the diameter of the cord. For example, passenger tires typically cannot exceed 30 ends per inch with minimum rivet or rubber spaced between the cords 2. In order to achieve a higher ends per inch fine cords 2 must be used and there is a limit to the strength of such fine cords 2. However, as the tire carcass with a flat formed ply expands into the toroidal configuration, the ply cord spacing or pitch is stretched in such a fashion that the cords per inch near the crown area 26 of the tire are oftentimes at least half the number in the bead area. This physical limitation can be corrected by the judicious use of the ply endings 12 in different diameters as illustrated in FIGS. 18 through 21. In FIG. 18, a cord spacing of 30 ends per inch could achieve a crown cord spacing of 30 ends per inch, the reason being the doubling of the cords in the crown area is achieved by shifting the looped end 12B slightly above the bead area 22. Thus in the toroidal shaped ply path 10 it is possible to maintain a uniform ply path all the way across the carcass structure. This enables the tire designer to possibly use finer cords or fewer cords and yet still achieve the same strength of present day tires.

With reference to FIG. 19, it is illustrated that one long ply cord path 10A can be used across the tire and then the two short ply cord paths 10B can be applied, then one long cord ply path 10A on the opposite side. The long ply cord paths 10A are circumferentially offset on a pattern of two short paths 10B being between each circumferentially offset long ply cord paths 10A; thereby four such ply cord path short ends 12B are on each side between the long ends 12A as illustrated in FIG. 19.

FIG. 20 shows a ply path construction whereby only one such short ply cord path 10B is between circumferentially offset long paths 10A. In FIG. 21, each ply cord path 10 creates a circumferentially offset long ply path 10A. Thus on each half of the ply cord path as shown in FIG. 21 there is a long 10A, then a short 10B, then a long ply cord path 10A formed by loop ends 12A, 12B, and 12C as shown.

With reference to FIG. 22, two ply cord paths 10A, 10B are shown that extend end to end in a repeating fashion. The ply cord paths 10A, 10B as illustrated show the possibility of creating two layers. A first layer of parallel ply cord paths 10A is shown with a curvature in one direction. The second ply cord path 10B of FIG. 22 could be a second layer of ply cord paths that could be applied continuously over the top of the first ply cord path 10A. Both of these ply cords paths 10A, 10B as illustrated in FIG. 22 illustrate the ability to make nonlinear cord paths in a uniform fashion. This technique greatly facilitates the construction of true geodesic ply path cord tires as a viable and manufacturingly feasible tire. Almost all nonlinear or geodesic type ply cord paths 10 are simply approximations due to the fact that the cords 2 are not laid in a fashion that is truly representative of the tire's internal shape or inflated shape as cured. As Purdy, in his book, Mathematics Underlying the Design of Pneumatic Tires, noted at page 84, “It is virtually impossible, by any acceptable means, to produce tire beads by the winding process that are uniform in size, shape, or in tension in the cords in the bead region. It is largely for such reasons that the cord winding machines have been of limited value in forming geodesic cord paths.” The present invention allows the ply cord paths to be placed in almost exactly the same positions as they will be in the cured tire thus making such non-linear plied tires feasible.

With reference to FIG. 23, the ply 20 shows how a standard tire currently manufactured could be built where all the ply endings 12 are at the same location.

With reference to FIG. 24 and FIG. 25, predetermined ply paths 10 are designed such that the sidewall will have an increased number of cords extending up toward the crown area 26 but will stop short of crossing the crown 26 at loop end 12B and will return by traversing back and then create a continuous ply across the entire toroidal surface 50. These ply paths 10, whereby only a portion of the ply cords 2 actually crosses the centerline of the tire under the crown area 26, can be advantageously used. In most light weight passenger and truck tires, the cords 2 crossing the centerline are of little structural value based in part to the tire's belt reinforcing structure which arguably transmits all the loads across the tire crown area 26. Accordingly, the use of a large number of ply cords 2 across the crown area 26 is a redundancy that adds no great structural value. What is interesting about the ply cord paths 10 of FIGS. 24 and 25 is that they take advantage of what otherwise could be entitled a split ply concept but with the advantage that at least every second or every third ply cord path 10 crosses the crown 26 creating enhanced structural value. In other words, instead of simply relying on split ply paths 10B these have an alternating continuous ply path 10A across the crown 26 that provides additional safety and reliability factors.

As will be appreciated from FIGS. 17 and 26, the toroidal surface 50 follows the curvature of a tire in substantially finished configuration and dimension. As explained, mandrel 52 has multiple concave curvatures forming surface 50; a concave curvature 120 on each side of the mandrel begins radially outward from the bead attachment area 22. A second sidewall outward curvature 122 extends radially outward from each first concave curvature outward toward the crown area 55 of the mandrel. As the mandrel cross section extends radially outward toward the upper sidewall portion 57, the curvature of the sidewalls 122 transitions to a convex curvature in what is otherwise known as the crown area 55 of the mandrel 52. The cross section closely duplicates the as molded cross section of a tire. As further depicted in FIGS. 15-17 and as previously explained, one or more cords in continuous lengths are embedded onto the elastomeric layer on surface 50. Longer cord paths 124 may be initiated radially opposite a first concave curvature 120 on one side of the mandrel and extend therefrom through the sidewall curvature and over the crown area 55. The longer cord path 124 may further extend to the first concave curvature 120 on the opposite mandrel side adjacent the bead attachment area 22.

Alternatively, or in conjunction with the longer cord paths 124, one or more shorter cord paths 126 may be formed. The shorter cord paths may initiate opposite a first concave curvature 120 on one side of the mandrel adjacent bead attachment area 22. The shorter cord path 126 may therefrom extend through the sidewall curvature 122 and over the crown area 55 or terminate within the sidewall curvature 122. The shorter cord path 126, extended over the crown area 55, may have a looped end located at the upper sidewall of the opposite mandrel side. Such a shorter cord path, such as depicted at 126, by ending at a higher location on the opposite sidewall of the mandrel, reduces the concentration of cord paths in the bead area of the tire. The shorter cord paths further conserve cord material in the finished tire and reduce manufacturing cost. Accordingly, cord paths forming a ply layer may be custom designed such that cord paths have differing path extensions and lengths. The shorter paths may terminate before crossing the equatorial plane of the mandrel (tire) or cross over the crown area to the sidewall on the opposite side. The longer paths may extend from bead attachment region 22 to bead attachment region 22 on the opposite side, crossing the crown region of the tire. As a result, a cord layer may be constructed having fewer cord paths present (lower cord path density) at the bead attachment area 22 and a higher ply cord path density at the crown region of the tire.

FIG. 17 represents one such cord ply configuration having cord paths of differing lengths. As illustrated in FIG. 17, a ply path 10 exists whereby loop ends 12B of a shorter cord path are placed and located radially outward of the sidewall curvature 122 of the surface 50. Loop ends 12A of longer cord paths are placed and located radially inward of surface 50 opposite the first concave curvature 120 at the bead attachment area 22. The loop ends 12B of the first set of adjacent pairs of cord paths 10 and the loop ends 12A of the adjacent set of cord paths are thus located at different respective radial locations relative to the first and second curvatures 120, 122 of the surface 50. It will be noted that ends 12A extend through the first and second concave curvatures 120,122 of the surface 50 to bead attachment area 22 while ends 12B terminate radially outward of the first concave curvature 120 opposite the sidewall of the surface 50. Consequently, fewer cord ends 12A are spaced radially below the first concave curvature 120 at the bead attachment area 22 than in the crown area where a higher cord path density exists.

A tire may accordingly be constructed having cord ply cord paths of differing lengths. A like number of longer and shorter cord paths, or a different number of longer and shorter paths may be employed depending on the tire performance characteristics desired. The longer cord paths may be constructed to extend over the crown of the tire surface 50 to the bead attachment areas. The shorter cord paths may be constructed to have loop ends that terminate either in the crown region, or the sidewall region. The cord paths may be advantageously constructed through placement and embedding one or more cords in continuous lengths onto the elastomeric layer in predetermined relatively longer and shorter cord paths, the longer cord paths extending from a respective side of the toroidal surface over the convex crown of the toroidal surface and one or more relatively shorter cord paths having opposite path ends located within a sidewall or crown region (refer to FIG. 18) or the convex crown of the toroidal surface. Thus, by having one or more cord paths extend between opposite path ends located radially outward of the first or second concave curvatures 120, 122 while other cord paths extend radially to the bead attachment area 22, the desired result of a higher cord density (cord paths per inch) at the crown area and a lower cord density at the bead attachment area may be achieved.

While the present invention has been illustrated by a description of various illustrative embodiments and while these embodiments have been described in some detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The various features of the invention may be used alone or in numerous combinations depending on the needs and preferences of the user. This has been a description of the present invention, along with the preferred methods of practicing the present invention as currently known. However, the invention itself should only be defined by the appended claims, wherein what is claimed is:

Claims

1. A method of manufacturing an annular toroidally shaped cord reinforced ply for a tire comprising the steps of: applying an elastomeric layer on a toroidal surface; and placing and stitching one or more cords in continuous lengths onto the elastomeric layer in predetermined cord paths, one or more first cord paths extending from a radially inward region of the toroidal surface and one or more second cord paths extending between path ends located radially outward of the radially inward region of the toroidal surface.

2. The method of manufacturing an annular toroidally shaped cord reinforced ply of claim 1, further comprising the step of: dispensing the one or more cords from one or more spools.

3. The method of manufacturing an annular toroidally shaped cord reinforced ply of claim 2 further comprising the step of: guiding the cord in predetermined paths as the cord is being dispensed.

4. The method of manufacturing an annular toroidally shaped cord reinforced ply of claim 1 further comprising: holding each cord against the elastomeric layer after the cord is placed and stitched; indexing the cord path to a next circumferential location; forming a loop end by reversing the direction of the cord; and releasing the held cord after the loop end is formed and the cord path direction is reversed.

5. The method of manufacturing an annular toroidally shaped cord reinforced ply of claim 4 wherein the step of forming loop ends occurs at opposite second ends of the second cord paths.

6. The method of manufacturing an annular toroidally shaped cord reinforced ply of claim 4 wherein the toroidal surface has a first concave curvature, a convex crown and a second concave curvature and the step of placing and stitching each cord includes traversing the cord across a path including at least one of the first or second concave curvatures and at least a portion of the convex crown.

7. The method of manufacturing an annular toroidally shaped cord reinforced ply of claim 4 further comprising the step of: forming ply turnups with the loop ends on each side of the toroidal surface.

8. The method of manufacturing an annular toroidally shaped cord reinforced ply of claim 5 wherein the step of forming the loop ends includes locating one loop end at a radially inner diameter di and one or more adjacent loop ends at a radially outer diameter do greater than di in a repeating pattern on each side of the toroidally shaped elastomeric surface.

9. The method of manufacturing an annular toroidally shaped cord reinforced ply of claim 5 wherein the step of forming the loop ends includes locating a plurality of the loop ends at a first radially inner diameter di and a plurality of other loop ends at one or more radially outer diameters do greater than di thereby forming ply paths having varying amounts of cords per inch at different locations on the toroidal surface.

10. A method of manufacturing an annular toroidally shaped cord reinforced ply for a tire comprising the steps of: applying an elastomeric layer on a toroidal surface wherein the toroidal surface has a first concave curvature, a convex crown and a second concave curvature; and embedding one or more cords in continuous lengths onto the elastomeric layer in predetermined cord paths, one or more first cord paths extending from a radially inward region of the toroidal surface and traversing at least one of the first or second concave curvatures; and one or more second cord paths extending between opposite path ends located radially outward of the first or second concave curvatures.

11. The method of manufacturing an annular toroidally shaped cord reinforced ply of claim 10 further comprising the step of extending one or more second cord paths to a radially outward second end located within the convex crown of the toroidal surface.

12. The method of manufacturing an annular toroidally shaped cord reinforced ply of claim 11 wherein the one or more second cord paths lie within a region bounded by at least one of the first or second concave curvatures of the toroidal surface and an equatorial plane of the toroidal surface.

13. The method of manufacturing an annular toroidally shaped cord reinforced ply of claim 11 further comprising the step of forming a loop at the radially outward second end of the one or more second cord paths.

14. The method of manufacturing an annual toroidally shaped cord reinforced ply of claim 13 wherein one or more second cord paths on opposite sides of the toroidal surface equatorial plane extend from a first end located radially outward of a respective one of the first or second concave curvatures to a radially outward second end located within the convex crown of the toroidal surface, the second ends of the second cord paths being located in spaced apart opposed relationship on opposite sides of the toroidal surface equatorial plane.

15. A method of manufacturing an annular toroidally shaped cord reinforced ply for a tire comprising the steps of: applying an elastomeric layer on a toroidal surface; dispensing a forward cord length into contacting relationship between the roller and the toroidal surface; embedding the forward cord length onto the elastomeric layer in a predetermined cord path as the roller progresses in a forward traverse across the toroidal surface in engagement against the forward cord length and the toroidal surface.

16. A method of manufacturing an annular toroidally shaped cord reinforced ply for a tire according to claim 15, further comprising the steps: holding the forward cord length against the elastomeric layer after the forward cord length is embedded; indexing the cord path to a next circumferential location; forming a loop end by reversing the direction of the forward cord length; and releasing the held forward cord length after the loop end is formed and the cord path direction is reversed.

17. A method of manufacturing an annular toroidally shaped cord reinforced ply for a tire according to claim 15, further comprising the steps: forming a loop end by reversing the direction of the forward cord length; positioning a reverse cord length into contacting relationship between the roller and the elastomeric layer; and embedding the reverse cord length onto the elastomeric layer in a predetermined cord path as the roller progresses in a reverse traverse across the toroidal surface in engagement against the reverse cord length and the elastomeric layer.

18. A method of manufacturing an annular toroidally shaped cord reinforced ply for a tire according to claim 17, further comprising the steps: holding the forward cord length against the elastomeric layer after the cord length is embedded in the forward traverse and the loop end is formed; indexing the cord path to a next circumferential location; and releasing the held forward cord length after the loop end is formed and the cord path direction is reversed.

19. A method of manufacturing an annular toroidally shaped cord reinforced ply for a tire according to claim 17, further comprising the step: engaging the forward cord length and the reverse cord length by respective rollers in the respective forward and reverse traverse of the lengths across the toroidal surface.

20. A method of manufacturing an annular toroidally shaped cord reinforced ply for a tire according to claim 15, further comprising the step of guiding the forward cord length along the predetermined cord path by the roller progressing in the predetermined cord path across the toroidal surface in engagement against the forward cord length and the toroidal surface.

21. A method of manufacturing an annular toroidally shaped cord reinforced ply for a tire comprising the steps of: applying an elastomeric layer on a toroidal surface wherein the toroidal surface includes opposite sides adjoining a toroidal surface equatorial plane, each side having a radially inward first region, a concave curvature disposed radially outward of the first region, a sidewall region disposed radially outward of the concave curvature and the sidewall region extending to a toroidal surface convex crown; and placing and embedding one or more cords in continuous lengths onto the elastomeric layer in predetermined relatively longer and shorter cord paths, the longer cord paths extending from a respective side of the toroidal surface over the convex crown of the toroidal surface and one or more of the relatively shorter cord paths having opposite path ends located within a sidewall region or the convex crown of the toroidal surface.

22. A method of manufacturing an annular toroidally shaped cord reinforced ply for a tire according to claim 21 further comprising the step of extending one or more of the longer cord paths to the radially inward region of a respective side of the toroidal surface.

23. A method of manufacturing an annular toroidally shaped cord reinforced ply for a tire according to claim 21 further comprising the step of locating one or more of the shorter cord paths within a respective side of the toroidal surface.

24. A method of manufacturing an annular toroidally shaped cord reinforced ply for a tire according to claim 21 further comprising the step of locating a plurality of the shorter cord paths on each side of the toroidal surface, the shorter cord paths of each side being in spaced apart relationship separated by an annular gap at the equatorial plane of the annular surface.

25. A method of manufacturing an annular toroidally shaped cord reinforced ply for a tire according to claim 21 further comprising the steps: holding each cord against the elastomeric layer after the cord is placed and embedded; indexing the cord path to a next circumferential location; forming a loop end by reversing the direction of the cord; and releasing the held cord after the loop end is formed and the cord path direction is reversed.

26. A method of manufacturing an annular toroidally shaped cord reinforced ply for a tire according to claim 21 further comprising the step of looping end to end the shorter cord paths a greater plurality of times on the sidewall region than the number of longer cord paths crossing the equatorial plane.

27. A method of manufacturing an annular toroidally shaped cord reinforced ply for a tire having an axis of rotation, comprising the steps of: applying an elastomeric layer on a toroidal surface having a convex crown bisected by an equatorial plane, and first and second sidewall regions located radially inward of the convex crown on opposite sides of the equatorial plane, embedding at least one length of cord into the elastomeric layer while extending the cord in a direction transverse to and across the equatorial plane between the first and second sidewall regions, and reversing the direction of the cord a plurality of times prior to crossing the equatorial plane thereby forming a greater number of cord paths on the first and second sidewall regions than at the convex crown.

28. The method of claim 27, wherein the cord paths on each of the first and second sidewall regions reverse directions at different radial distances from the axis of rotation.

29. A method of manufacturing an annular toroidally shaped cord reinforced ply for a tire having an axis of rotation, comprising the steps of: applying an elastomeric layer on a toroidal surface having a convex crown bisected by an equatorial plane, and first and second sidewall regions located radially inward of the convex crown on opposite sides of the equatorial plane, embedding at least one length of cord into the elastomeric layer while extending the cord in a direction transverse to and across the equatorial plane between the first and second sidewall regions, reversing the direction of the cord at different radial distances from the axis of rotation on the first sidewall region, and reversing the direction of the cord at different radial distances from the axis of rotation on the second sidewall region.