EP0191773A4

EP0191773A4 - Channelled woven belt for a tire and apparatus and method for making the belt.

Info

Publication number: EP0191773A4
Application number: EP19850902914
Authority: EP
Inventors: William J Thomas
Original assignee: Armstrong Rubber Co
Current assignee: Pirelli Armstrong Tire Corp
Priority date: 1984-08-29
Filing date: 1985-06-03
Publication date: 1987-01-22
Also published as: MX161301A; AU4463785A; PT80963B; AU581236B2; ES295958U; PT80963A; EP0191773A1; JPS62500092A; NO853368L; ES295958Y; CA1259154A; WO1986001464A1

Abstract

A channelled woven belt for use in the manufacture of a tire, as well as a method of making the belt and the belted tire. A woven belt in accordance with the invention comprises a plurality of tapes each comprising an elongated strip of elastomeric material reinforced with a plurality of reinforcing cords. The cords extend lengthwise in the elongate strip, and each strip has a plurality of channels extending laterally with respect to the strip to permit flow of air from one edge of the strip to the other. When the strips are interwoven and laid surface to surface, a plurality of interstices are formed between the tapes, and the channels permit air to flow out of the woven belt during tire manufacture.

Description

CHANNELLED WOVEN BELT FOR A TIRE AND APPARATUS AND METHOD FOR MAKING THE BELT

BACKGROUND OF THE INVENTION (1) Field of the Invention

The present invention relates to woven belts for belted tires, either radial, bias belted or bias with belts, and more specifically, to a construction of the woven belt and the plurality of tapes which form the woven belt such that air is channelled from the interstices between these tapes during tire manufacture. (2) Discussion of the Prior Art

Belted tires utilize multiple ply composite belts to reinforce the tread region of the tire. The tire in- eludes a carcass on the interior, a reinforcing composite belt adjacent to the carcass, and a tread region adhered to the composite belt and the carcass of the tire.

Various types of composite belts are used in the construction of belted tires, and include basically three types. One type of composite belt system is a "cut belt" construction which consists of polymeric material reinforced with cords that are in the form of sheet like material cut along its edges. In a typical construction, two separate plies are used and the cords of one ply cross the cords of the second ply. In all cut belt systems, regardless of the number of plies, the cut cords are at the lateral edges of the belt, and are disadvantageous for several reasons including the tendency of the tread to separate in the region where the cut cords are exposed at the lateral edges of the tire. _ _

Another type of composite belt is what is known as a "folded belt" construction wherein the lateral edges of cut cords are enveloped by a folded sheet of reinforced cord material. A third type of belt, is a "woven belt" and com¬ prises a plurality of tapes interwoven and laid surface to surface, wherein each tape comprises a elastomeric material reinforced with a plurality of spaced apart reinforcing cords extending lengthwise within the strip. The tapes are typically woven in zig zag pattern so that the lateral edges of the belt are smooth, and do not contain exposed cord ends. When the tapes are woven in a zig zag pattern a large number of interstices are formed between the tapes. Examples of woven belts are disclosed in U.S. Patent Nos. 3,589,426; 3,674,079; 3,598,166; 3,720,569 and 3,720,570.

During tire manufacture, the woven belt is placed around the tire carcass, and a tread length is placed over the woven belt and "stitched" to the carcass and the belt. The term "stitched" as known in the art means pressing the tread against the underlying belt and carcass to form an uncured tire, which is thereafter placed in a mold and cured under heat and pressure. During this stitching phase of tire manufacture, the tread is forced against the belt and carcass by two rollers, each of which is in contact with the tread and moves from the center of the tire to its shoulder as the tire is rotated. During the stitching phase of tire manufacture, air may become trapped in the interstices between the tapes of the woven belt, and may remain in the tire after the tire has been cured and is ready for use.

It is a principle object of the present inven¬ tion to reduce or eliminate air trapped in the interstices of the woven belt during the manufacture of a tire. It is another object of the present invention to provide a method of manufacturing a tape to be woven to form a woven belt of a tire wherein the tape permits the air to be forced -3-

from the interstices of the belt during tire manufacture.

SUMMARY OF THE INVENTION In accordance with one aspect of the invention, a tape for use in a woven belt of a tire is provided and comprises an elongate flat strip made from elastomeric material reinforced by a plurality of spaced apart rein¬ forcing cords. The cords extend lengthwise in the strip and the strip has a generally rectangular cross section defined by upper and lower ^"surfaces and two edges. A plurality of channels are formed in a surface of the strip and extend laterally between the edges thereof to permit air flow between the edges of a given strip. When the tapes are interwoven to form a woven belt for a belted tire, the tapes are laid surface to surface and a number of interstices are formed between the belts. The channels formed in the tapes form a grid-like network of passageways which permit the flow of air to the edges of the woven belt when the tire is assembled for curing.

When the tread is stitched to the woven belt and the carcass which underlies the belt, the air in the interstices of the woven belt is- forced laterally outwardly from the belt thus reducing or eliminating the amount of air entrapped in the finished tire.^' It should be under¬ stood that during stitching operation, pressure is applied to the tread to adhere it to the belt and the carcass. The pressure is applied by a pair of rollers that move from the center of the tire away from each other to the shoulders of the tire while the tire is rotated with respect to the rollers. Thus, force is initially exerted on the tread on the center of the tire and the air is squeezed laterally outwardly from the interstices in the belt through the channels as the rollers move laterally from the center of the tire to the shoulder of the tire.

In accordance with one aspect of the invention an apparatus and a method for forming the channels in the tape or the woven belt formed from a plurality of tapes is disclosed. The apparatus comprises a first cylindrical _ _

roller having an axis and a second cylindrical roller having an axis extending parallel to the axis of the first roller. The rollers are spaced apart to accommodate pass¬ ing of the tape therethrough. At least one of the rollers has an outer cylindrical surface including a plurality of protrusions extending axially along the outer surface of the roller and spaced from each other about the circumference of the roller. As the tape is passed between the rollers, the protrusions form channels in the tape. In the case where it is desirable to form channels in the woven belt formed from a plurality of tapes, the rollers are spaced apart to accommodate the woven belt and the protrusions form channels in the surface of the woven belt. In accordance with one aspect of the invention, both rollers may have the protrusions on the outer surface thereof, and the protrusions of each roller are spaced so that the protrusions are located in face to face relation to provide two air channels, one on either side of the tape. Additional advantages and other aspects of the invention will be set forth in the detailed description of the invention with reference to the drawings which follows. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a perspective view of an apparatus for forming channels in a tape in accordance with the present invention;

FIG. 2 shows an enlarged perspective and sectional view of a tape in accordance with the present invention; FIG. 3 shows a sectional view along the plane

3-3 Of FIG. 2;

FIG. 4 is an exploded sectional view showing the tape shown in FIG. 2 interwoven to form a woven belt and wherein the tread of the tire is being stitched to the belt and carcass;

FIG. 5 shows a perspective view of an apparatus for forming channels on both sides of a woven belt; and -5-

FIG. 6 shows a perspective view of the belt shown in FIG. 5 during manufacture of a belted tire wherein the tread is being stitched to the belt and carcass of the tire. DETAILED DESCRIPTION OF THE INVENTION

Referring to Figure 1, an apparatus for extruding tape is shown schematically at reference character 10. The tape 12 comprises an elastomeric material reinforced by a plurality of spaced apart reinforcing cords 14 which extend lengthwise in the elongate strip. As shown in Figures 2 and 3, the strip has upper and lower surfaces 16 and 18 and edges 20 and 22. The extruded tape binder is an elastomeric material such as uncured rubber or other suitable materials. Rubber as used herein means natural or synthetic elasto¬ meric polymers or copolymers, or mixtures thereof, useful in composite construction such as in tires. The plurality of spaced cords may be made from polyester, aramid, glass, steel, nylon, cotton and other materials. The cords are typically made from a number of twisted strands and are generally uniformally spaced along the width of the tape, but other spacing configurations can be used. When the uncured rubber tape is extruded from machine 10, it is still warm and capable of being formed. As shown in Figure 2, a tape in accordance with the present invention includes a plurality of channels 24 extending laterally with respect to the strip between the edges 20 and 22 to permit flow of air from edge to edge. The channels are spaced apart from each other along the length of the strip.

As shown in Figure 2, the channels 24 extend laterally from edge to edge, and preferably extend at a right angle with respect to the lengthwise direction of the tape. However, it should be understood that other patterns of channels may be used provided the channel shape permits flow of air from edge to edge. The channels are uniformally spaced from each other, but the spacing -6- CT/US85/01033

of the channels may be irregular or may have a pattern other than that shown.

Once a tape having a plurality of channels is formed, it is interwoven to produce a woven belt 26 as shown in Figure 4. The tapes can be woven in numerous patterns, such as those disclosed in the patents cited as prior art above. When the tapes are interwoven, a multi¬ tude of interstices 28 are formed between the edges of the tapes. During a conventional tire forming process, air may become entrapped in these interstices and small voids may be formed in the tire. As can be appreciated by view¬ ing Figure 4, the large number of channels in these tapes form a grid-like network of passages which permits flow of air laterally within the belt. Referring to Figure 4, during tire manufacture, the belt 26 is placed over a tire carcass 30 and a strip of tread 32 of uncured rubber is placed over the belt. The uncured rubber of the tread 32 is in a soft uncured state and can be adhered to the woven belt 26 by downward pressure of rollers 34 and 36. The rollers 34 and 36 are moved in the direction of arrows 38 and 40 from the center of the tire to the tire shoulder 42. Since the pressure is applied at the center of the tire by both rollers, air in the interstices near the center of belt 26 is driven laterally toward the shoulders of the tire. As the rol¬ lers 34 and 36 move outwardly from the center of the tire, the entrapped air continues to be forced outwardly toward the shoulder so that as the rollers move out outwardly and than down the shoulder of the tire, the air is expelled from the interior of the tire. Thus, by using a channelled tape in accordance with the present invention, conventional tire making equipment may be used to expell the air, and no major redesign of the tire making ap¬ paratus is necessary. As the rollers 34 and 36 move over the tread 32, pressure is applied to the tread and translated to the tapes 12. The rubber of the tapes 12 during stitching flows as pressure is applied and a firm bond is provided between the tread and the tapes of the woven belt. Subsequent to the stitching step in tire manufacture, the tire is cured under pressure and heat and the tape rubber flows further to provide a bond between the tape rubber and the tread rubber.

Referring once again to Figure 1, the apparatus and method for forming the channels in the tape, will be described. The apparatus comprises first and second -cylin- drical rollers 50 and 52 each having an axis 54 and 56.-

The two axes extend in parallel relation to each other and are spaced apart to accommodate the passing of the tape 12 therethrough. Cylindrical roller 50 has an outer cylin¬ drical surface 58 including a plurality of protrusions 60 extending axially along the outer surface of the roller and spaced apart from each other the protrusions 60 have a generally rectangular cross section and provide a chan¬ nel in the tape having a substantially identical cross section. The cylindrical surface 62 of roller 52 func- tions as an anvil, supporting the underside of the tape.

After the tape 12 has passed through first and second cylindrical rollers 50 and 52, the tape includes channels on one side thereof. Depending upon the type of reinforcing cord used, an impression may be made on the surface opposite that in which the channels are formed. More specifically, it has been found that when using aramid and other synthetic reinforcing cords, a small channel is formed on the side of the tape opposite that in which channels are intended to be formed. These smaller channels may also aid in permitting air to be forced out of the tire during tire manufacture. In instances where it is desirable to form channels on both sides of the tape, the apparatus described below with respect to Figure 5 may be used. It may be necessary to form channels on both sides of the tape when steel reinforcing cords are used and that the impression from the protrusions 60 may not form small channels on the opposite side of the tape into which the protrusions 60 are pressed. Thus, when using steel reinforcing cords, it may be desirable to use an apparatus of the type described below in Figure 5 to provide channels on both sides of the tape. Referring to Figure 5, an apparatus for forming channels in both sides of the woven belt 26 is shown. The roller 70 includes protrusions 71 and is substantially identical to roller 50 in Figure 1 with the exception that the roller is wider so that it spans the entire width of woven belt 26. Roller 72 is identical to roller 70 and includes a series of protrusions 74. Rollers 76 and 78 are positioned on the side of woven belt 26 opposite re¬ spectively rollers 70 and 72. Roller 70 extends in sub¬ stantially parallel in relation to roller 76. Roller 78 also extends in substantially parallel in relation to

Roller 72. As the woven belt 26 is passed through the two sets of rollers, it is first pressed on one side to provide channels 80 and then on the other to provide channels 82. The channels 80 and 82 extend from one edge of the belt 26 to the other edge of the belt thus providing passages for the air to be expelled from the interstices of the belt. It should be understood that the apparatus shown in Figure 5 is shown forming channels on a belt made from a plurality of tapes 12, rather than a single tape. If it is desirable to form channels on both sides of a tape, an apparatus similar to that shown on Figure 5 may be used wherein channels are formed on both sides of the tape by two opposed rollers each of which have protrusions. The tire shown in Figure 6 corresponds to that of the tire shown in Figure 4 with the exception that the woven belt has lateral grooves 80 and 82 extending the entire width of the belt rather than the large number of grooves for each tape of the belt. It should be under- stood that during the stitching of the tread 90 onto the carcass 92, air is moved laterally outwardly from the center of the woven belt to the shoulder of the tire by the imposition of conventional stitching rollers which compose a force which is moved from the center of the tire toward the shoulder.

In accordance with one aspect of the invention, the channels 24 are formed having a sufficient depth to expose a length of the reinforcing cord. More specifi¬ cally, referring to Figure 2, the channels 24 have a depth sufficient to expose upper surfaces 25 of the cords 14. The cords 14 are typically made from twisted strands having small air spaces between the strands. To the extent some air is not forced out of the tire through channels 24, such air may enter the reinforcing cord thereby avoiding or minimizing entrapment of air in the rubber.

In summary, by use of a tape having a plurality of channels wherein the tapes are formed into a woven belt or, alternatively, a woven belt where the channels are formed in the belt, provides distinct advantages over prior art constructions in that air that is typically entrapped in a conventional belted tire is forced out of the woven belt thus providing a tire with few or no voids. The present invention is applicable to various types of belted tires including radial, bias belted or bias with belts type tires.

It should be understood that although specific embodiments of the invention have been described herein in detail, such description is for purposes of illustration, only and modifications may be made thereto by those skilled in the art within the scope of the invention.

Claims

3 AMENDED CLAIMS

[received by the International Bureau on 28 October 1985 (28.10.85); original claim 7 amended; other claims unchanged (1 page)] and between the sides of said tape to provide for flow of air from edge to edge of the tape and between said inter- stices, said channels being spaced apart from each other along the length of said tape, said channels of said tapes forming a grid-like network of passages permitting flow of air from one belt edge to the other.

7. A belt according to Claim 6 wherein said channels extend at a right angle with respect to said lengthwise ₈direc£i_? of_csaid_nta_?Ss_{clalm ? wherein each} said channels comprises grooves formed on at least one surface of each said tape.

9. A belt according to Claim 5 wherein said channels extend laterally from side to side across the continuous integral belt structure.

10. A belt according to Claim 9 wherein said channels are spaced apart from each other along the major axis of said structure and are formed on at least one said surface of said structure; il. A belt according to Claim 10 wherein said channels are formed along both said surfaces of said belt.

12. A method for making a woven belt for a belted tire, the method comprising providing a strip of elastomeric material, having two surfaces and two edges, said material encasing a plurality of spaced apart . reinforcing cords running the length of said strip; forming on at least one surface of said strip a plurality of grooves extending laterally between said edges, said grooves being spaced apart along the length of said strip and then forming a plurality of said strips into a belt.

13. A method according to Claim 12 wherein said forming step comprises forming an impression on the surface of said strip.

14. A method according to Claim 13 wherein said forming of said impression comprises pressing an elongated protrusion against said strip surface to deform said polymeric material.