METHOD FOR MANUFACTURING A SINGLE BELT/OVERLAY COMPONENT FOR A PNEUMATIC TIRE

Abstract

A method in accordance with the present invention manufactures a tire with a biaxial monolayer belt component (MBC). The method comprises the steps of: winding a cord continuously about a first drum according to a pre-defined pattern to create a mesh of cords defining a single belt/overlay structure; adjusting the structure to a predetermined position on the first drum by laser lights; applying a tread component to the structure; transferring the structure and tread component to a second drum; applying the structure and tread component to a carcass component on the second drum; reducing pressure of the carcass component by a predetermined amount; and stitching the structure and tread component to the carcass component.

Claims

1. A method for manufacturing a tire with a biaxial monolayer belt component (MBC), the method comprising the steps of: winding a cord continuously about a first drum according to a pre-defined pattern to create a mesh of cords defining a single belt/overlay structure; adjusting the structure to a predetermined position on the first drum by laser lights; applying a tread component to the structure; transferring the structure and tread component to a second drum; applying the structure and tread component to a carcass component on the second drum; reducing pressure of the carcass component by a predetermined amount; and stitching the structure and tread component to the carcass component.

2. The method as set forth in claim 1 wherein the predetermined amount is in the range between 100 mbar and 600 mbar.

3. The method as set forth in claim 1 further including the steps of: individually dipping the cord; and individually tackifying the cord.

4. The method as set forth in claim 1 wherein the cord is part of a plurality of individually dipped and individually tackified cords.

5. The method as set forth in claim 1 wherein the cord is constructed of two twisted aramid yarns.

6. The method as set forth in claim 1 wherein the structure is disposed radially between the tread component and the carcass component.

7. The method as set forth in claim 1 wherein the cord is constructed of one of the following materials: aramid, PEN, PET, PVA, PBO, POK, rayon, nylon, carbon, and glass fiber.

8. The method as set forth in claim 1 wherein the carcass component comprises uncured rubber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Further aspects of the present invention will become apparent from the description of the following embodiments in conjunction with the attached diagrammatic drawing, in which:

[0065] FIG. 1 represents a schematic cross-sectional view of an example tire constructed in accordance with the present invention;

[0066] FIG. 2 represents a schematic detail view of the bead region of the example tire shown in FIG. 1;

[0067] FIG. 3 represents a schematic detail view of a belt ply constructed in accordance with the present invention;

[0068] FIG. 4 represents a schematic detail view of another belt ply constructed in accordance with the present invention; and

[0069] FIG. 5 represents a schematic detail view of still another belt ply constructed in accordance with the present invention.

DESCRIPTION OF AN EXAMPLE EMBODIMENT

[0070] The example tire 1 of FIG. 1 includes a pair of sidewalls 8, 9 terminating in bead regions 10, 11. Each bead region 10, 11 is reinforced by an inextensible annular bead core 12, 13. Extending between each bead region 12, 13 is a tire carcass reinforcement ply structure 14 of one or more plies which is/are anchored in each bead region 10,11 by being turned around each respective bead core 12, 13 laterally from inside to outside to form each ply turn-up 15, 17. The carcass reinforcement ply structure 14 may, for example, comprise a single ply of nylon fabric cords oriented substantially in a radial direction. Each bead region 10, 11 may further comprise a hard rubber apex member 17, 18 anchored to each respective bead core 12, 13 and narrowing/tapering radially outward. The carcass ply fabric of the example tire 1 may also comprise polyester, rayon, nylon, or para-aramid cords.

[0071] The example tire 1 may have a convex tread region 2, having tread edges 3, 4 reinforced by an integral breaker assembly (or belt structure/overlay 16) in accordance with the present invention. The assembly may be a filament wound, or single end dipped, reinforcement that integrates the functionality of the belt and overlay to construct a single band of reinforcement in accordance with the present invention.

[0072] Conventional pneumatic tire designs have been based on classical composite laminate principles having several reinforcement layers in which cords are laid parallel to each other. Due to the unidirectional load carrying capability of each reinforcement layer, several such layers are stacked up to manage the force transfer in several directions. A minimum of two such reinforcement layers of steel wires has been used as a belt package along with an additional layer of reinforcement as an overlay for enhancing high speed performance Inherent disadvantages of this conventional design are excess weight with few possible weight reductions.

[0073] The assembly 16 may eliminate the inherent disadvantages of conventional reinforcement constructions by integrating belt and overlay functionality using rubberized filament winding technology to construct a single assembly 16. Such an integral assembly 16 may further reduce weight narrowing the overlay portion of the assembly without sacrificing performance characteristics (FIG. 1).

[0074] As shown in FIG. 3, the cords 305 of the wider belt portion of the assembly 16 may have equal or unequal angles relative to the circumferential direction of the tire 1 between 45 and +45. The cords 305 of the thinner overlay portion of the assembly 16 may have equal or unequal angles relative to the circumferential direction of the tire 1 between 45 and +45. The cords 305 may be symmetrically or asymmetrically wound and have 5-32 epi (ends per inch).

[0075] As shown in FIG. 4, the cords 405 of the wider belt portion of the assembly 16 may have equal or unequal angles relative to the circumferential direction of the tire 1 between 45 and +45. The cords 405 of the thinner overlay portion of the assembly 16 may have equal or unequal angles relative to the circumferential direction of the tire 1 between 45 and +45. The cords 405 may be symmetrically or asymmetrically wound and have 5-32 epi (ends per inch).

[0076] As shown in FIG. 5, the cords 505 of the wider belt portion of the assembly 16 may have equal or unequal angles relative to the circumferential direction of the tire 1 between 45 and +45. The cords 505 of the thinner overlay portion of the assembly 16 may have equal or unequal angles relative to the circumferential direction of the tire 1 between 45 and +45. The cords 505 may be symmetrically or asymmetrically wound and have 5-32 epi (ends per inch).

[0077] The assembly 16 may comprise single end dipped cords 305, 405, 505 which are individually dipped and subsequently individually tackified (i.e., not calendered). While the cords 305, 405, 505 may be individually dipped, a group 303, 403, 503 of several cords may also be dipped concurrently, moving through a dip process/machine in parallel. For example, the individual cords may be monofilaments, para-aramid 1680/3 Dtex with 240/240 tpm (turns per meter) or other suitable configurations. The selection of materials for the tackified finish may depend greatly upon the materials selected for use in the tire 1. One of ordinary skill may determine such suitable materials. Tackified finishes may be achieved by various methods such as coating the single end cords in an aqueous or solvent blend of resin and rubber lattices.

[0078] An example method may comprise the steps of: first, pretreating an individual cord by dipping the cord in a first solution or emulsion; second, drying the individual cord; third, tackifying a surface of the dipped and dried individual cord with a second solution or emulsion; and fourth, applying the tackified individual cord on a surface of an uncured tire component.

[0079] The second solution or emulsion may comprise a conventional un-vulcanized rubber compound dissolved in a solvent. Preferably, the solvent comprises a petroleum derivative or distillate such as toluene.

[0080] The dipping may include a treatment of the individual cord with an adhesion promoter as part of the dipping process. Typical examples of adhesion promoters include resorcinol formaldehyde latex (RFL), isocyanate based material, epoxy based material, and materials based on melamine formaldehyde resin. To this end, the dipping may include dipping the individual cord in the first solution or emulsion (or in a first bath) and subsequently dipping the dipped individual cord in a further solution or emulsion (or a second bath) prior to the drying step.

[0081] Preferably, the further solution or emulsion is an aqueous emulsion (dispersion) comprising a rubber latex containing resorcinol formaldehyde (RFL) resin. The RFL resin may be a primary element of adhesion between the cord and the rubber with the latex also reducing the modulus of the RFL resin.

[0082] The tackifying of the surface of the dipped and dried individual cord includes applying a tackified finish for facilitating adhesion, or green tack, during the building process of the green tire. The selection of materials for such tackified finish will depend greatly upon the materials selected for use in the tire, and the skilled person on the basis of his common knowledge can easily determine them appropriately. Tackified finishes can be achieved by various methods such as coating the cord in an aqueous blend of rosin and rubber lattices, or with a solvent solution or emulsion of an un-vulcanized rubber compound.

[0083] During building of the uncured tire, the cords 305, 405, 505 of the assembly 16 may be individually placed directly upon an outermost of one or two carcass plies 14, without any intermediate manufacturing process. The assembly 16 may thus provide a tread crown reinforcement structure and may optimize high speed performance, as well as provide excellent handling characteristics, while reducing overall manufacturing efficiency, cost, and weight. The present invention accomplishes this by utilizing the individually dipped and individually tackified Single End Dipped (SED) cord(s) 305, 405, 505 to integrate the belt and overlay structures. Suitable materials for the SED cords 305 may be aramid, PEN, PET, PVA, PBO, POK, Rayon, Nylon 6, 4,6 and 6,6, carbon, and/or glass fiber. Additionally, the cords 305, 405, 505, 605 may be calendered in small tapes or strips 303, 403, 503 of 1, 2, 3, 4, etc. cords.

[0084] The cords 305, 405, 505 may be first dipped in a first classical solution and, in a second phase, tackified by a second solution or emulsion (as described above). Once the cord 305, 405, 505 is tackified, the cord will have enough cohesive properties to adhere to an unvulcanized component, such as the carcass 14. This provides an improvement over conventional tire building methods, which include an additional calendering step and often generate a higher amount of scrap. Further, cord properties may not be affected by calendering and storage. Also, the process provides a simpler and more efficient method, since no weft yarns are needed for weaving and calendering.

[0085] This ready to use SED cord assembly 16 may provide a jointless belt/overlay having a better controlled tension applied to the cords 305, 405, 505 during winding at a tire building machine. This may be critical for strips with multiple cords due to the curvature of a radial carcass 14. The cords 305, 405, 505 at the tread edges 3, 4 may have significantly shorter length compared to the cords at the center of the tread 2.

[0086] A method in accordance with the present invention manufactures a tire with a biaxial monolayer belt component (MBC) 116. The MBC 116 may be constructed by winding a single cord 305, 405, 505 or tape 303, 403, 503 of multiple parallel cords according to a pre-defined pattern to create a mesh of cords which may be dedicated to replace conventional belt(s) and overlay(s) in a conventional tire. The MBC 116 may have a higher green gauge than a conventional belt package of two breakers and an overlay, a reduced stretch compliance, and a single, continuously wound cord forming a mesh rather than conventional breakers which are made with independent cords set side by side.

[0087] This mesh may drive the use of much bigger belt building diameters for the preparation of the MBC and reduce the so called dog bone effect created by cords piling up at edges of the MBC 116. The dog bone effect is highly dependent on the winding pattern used to create the mesh.

[0088] The MBC 116 may be applied similarly to a conventional belt package. The MBC 116 may be placed on a belt building drum at a tire building machine and the belt building drum may be expanded to the same diameter as an MBC drum. The MBC 116 may be adjusted to the predetermined position by laser lights of the belt building machine. A tread component 2 may subsequently be applied on the MBC 116. A transfer ring may then pick-up the MBC 116 (with the tread 2) and transfer it to a second stage drum.

[0089] The MBC 116 and tread 2 may then be applied on a green carcass component 14 as conventionally achieved. However, the inflation pressure of the green carcass component 14 may be decreased by 200 mbar in order to reduce green tire growth during tread stitching operations. Not reducing the inflation pressure may lead to a larger green tire than is required before curing.

[0090] The MBC 116 may be transferred to the green carcass 14 before setting of the tread component 2. The MBC 116 may be set on the belt building drum at the tire building machine and the belt building drum may expand to the same diameter as the MBC. The MBC 116 may be transferred by the transfer ring to the green carcass 14 or set manually on the green carcass. If the MBC 116 is set manually, the MBC may be aligned accurately with the middle of the green carcass 14.

[0091] The MBC 116 may be stitched on the green carcass 14 with an adjusted inflation pressure. The tread component 2 may then be set manually on the MBC 116 and green carcass 14 assembly before automatically stitching at usual inflation pressure minus 200 mbar, as described above. Winding time may be greatly reduced compared to conventional winding times in order to be close to the time needed to assemble the two steel breakers and the overlay in today's standard building process.

[0092] Conventional times for setting breaker 1, breaker 2, and an overlay directly on the tire building machine may be greatly reduced by installing just the prefabricated MBC 116. Further, the weight of the MBC 116 may be reduced by as much as 20%.

[0093] As stated above, an assembly 116 of SED cords produces excellent handling performance in a tire 1, as well as reducing manufacturing cost and weight. Further, a method in accordance with the present invention provides enhanced efficiency and reduced cost for constructing a pneumatic tire. Thus, the SED cords 305, 405, 505 and method both enhance the performance and/or manufacturing of a pneumatic tire, even though the complexities of the structure and behavior of the pneumatic tire are such that no complete and satisfactory theory has been propounded. Temple, Mechanics of Pneumatic Tires (2005). While the fundamentals of classical composite theory are easily seen in pneumatic tire mechanics, the additional complexity introduced by the many structural components of pneumatic tires readily complicates the problem of predicting tire performance Mayni, Composite Effects on Tire Mechanics (2005). Additionally, because of the non-linear time, frequency, and temperature behaviors of polymers and rubber, analytical design of pneumatic tires is one of the most challenging and underappreciated engineering challenges in today's industry.

[0094] A pneumatic tire has certain essential structural elements. United States Department of Transportation, Mechanics of Pneumatic Tires, pages 207-208 (1981). An important structural element is the overlay, typically made up of many flexible, high modulus cords of natural textile, synthetic polymer, glass fiber, or fine hard drawn steel or other metal embedded in, and bonded to, a matrix of low modulus polymeric material, usually natural or synthetic rubber. Id. at 207 through 208.

[0095] The flexible, high modulus cords are usually disposed as a single layer. Id. at 208. Tire manufacturers throughout the industry cannot agree or predict the effect of different twists of overlay cords on noise characteristics, handling, durability, comfort, etc. in pneumatic tires, Mechanics of Pneumatic Tires, pages 80 through 85.

[0096] These complexities are demonstrated by the below table of the interrelationships between tire performance and tire components.

TABLE-US-00001 CARCASS LINER PLY APEX BELT OV'LY TREAD MOLD TREAD WEAR X X X NOISE X X X X X X HANDLING X X X X X X TRACTION X X DURABILITY X X X X X X X ROLL RESIST X X X X X RIDE X X X X COMFORT HIGH SPEED X X X X X X AIR X RETENTION MASS X X X X X X X

[0097] As seen in the table, belt/overlay cord characteristics affect the other components of a pneumatic tire (i.e., belt/overlay affects apex, carcass ply, tread, etc.), leading to a number of components interrelating and interacting in such a way as to affect a group of functional properties (noise, handling, durability, comfort, high speed, and mass), resulting in a completely unpredictable and complex composite. Thus, changing even one component can lead to directly improving or degrading as many as the above ten functional characteristics, as well as altering the interaction between that one component and as many as six other structural components. Each of those six interactions may thereby indirectly improve or degrade those ten functional characteristics. Whether each of these functional characteristics is improved, degraded, or unaffected, and by what amount, certainly would have been unpredictable without the experimentation and testing conducted by the inventors.

[0098] Thus, for example, when the structure (i.e., twist, cord construction, etc.) of the overlay of a pneumatic tire is modified with the intent to improve one functional property of the pneumatic tire, any number of other functional properties may be unacceptably degraded. Furthermore, the interaction between the overlay and the apex, carcass ply, belt (or breaker), and tread may also unacceptably affect the functional properties of the pneumatic tire. A modification of the overlay may not even improve that one functional property because of these complex interrelationships.

[0099] Thus, as stated above, the complexity of the interrelationships of the multiple components makes the actual result of modification of a method in accordance with the present invention, impossible to predict or foresee from the infinite possible results. Only through extensive experimentation have the method of the present invention been revealed as an excellent, unexpected, and unpredictable option for a pneumatic tire.

[0100] The previous descriptive language is of the best presently contemplated mode or modes of carrying out the present invention. This description is made for the purpose of illustrating an example of general principles of the present invention and should not be interpreted as limiting the present invention. The scope of the invention is best determined by reference to the appended claims. The reference numerals as depicted in the schematic drawings are the same as those referred to in the specification. For purposes of this application, the various examples illustrated in the figures each use a same reference numeral for similar components. The examples structures may employ similar components with variations in location or quantity thereby giving rise to alternative constructions in accordance with the present invention.