GB1601100A

GB1601100A - Method of building a radial tyre

Info

Publication number: GB1601100A
Application number: GB658678A
Authority: GB
Original assignee: Goodyear Tire and Rubber Co
Current assignee: Goodyear Tire and Rubber Co
Priority date: 1977-03-28
Filing date: 1978-02-20
Publication date: 1981-10-21
Also published as: FR2385518A1; DE2813702C2; FR2385518B1; DE2813702A1; BR7801630A; AU514919B2; CA1082863A; LU79245A1; AU3371678A

Description

(54) A METHOD OF BUILDING A RADIAL TIRE (71) We, THE GOODYEAR TIRE & RUBBER COMPANY, a corporation organised under the laws of the State of Ohio, United States of America, of 1144 East Market Street, Akron, Ohio, United States of America, do hereby declare the invention, for which we pray that a patent may by granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to radial tires and to the production of radial tires, especially but not exclusively to radial truck tires having a belt structure of metal reinforcement cords.

According to this invention, there is provided a method of building a radial tire, comprising the steps of: (a) providing a beltless tire casing mcluding: (I) at least one carcass ply reinforced with radially oriented (as herein defined) cords, and (II) a pair of inextensible bead cores secured to said carcass ply; (b) positioning an unvulcanized belt structure comprising at least one belt ply of unvulcanized material, reinforced with tire cords, circumferentially around the outer periphery of the shaped beltless tire casing, and, before positioning the belt structure, positioning a restrictor band which is separate from and narrow relative to the belt structure circumferentially about the outer periphery of the beltless tire casing to lie between the belt structure and the tire casing; (c) placing a tread circumferentially around the belt structure positioned on the beltless tire casing; and td) vulcanizing any unvulcanized components of the tire, including the belt structure, the restrictor band serving to prevent expansion of the beltless tire casing beyond the diameter it takes up when the tire is vulcanized and molded.

According to a feature of this invention there is provided a radial tire built by the method according to this invention and comprising: (a) at least one carcase ply reinforced with radially oriented (as herein defined) reinforcement cords; (b) a tread and pair of sidewalls surrounding the said at least one carcass ply, each sidewall having at its edge, an inextensible annular bead; (c) a belt structure positioned between the tread and the or the radially outermost carcass ply of the tire; and (d) a restrictor band of substantially inextensible cords interposed between the belt structure and the or the radially outermost carcass ply of the tire, the restrictor band being separate from the belt structure and narrow relative to the belt structure.

The technology employed in the invention is somewhat similar to that described in our Application No. 6022/77 (1,578,164), on the retreading and rebuilding of a radial tire, rather than in the formation of a new tire. The invention also envisages the use of a precured tread in combination with an unvulcanized belt structure.

An embodiment of the invention will now be described with reference to the accompanying drawings, wherein: Fig. 1 is a section of a radial tire made in accordance with the invention; Fig. 2 is a section of a beltless radial tire casing and mold in which the casing is molded and vulcanized; and Fig. 3 is a section of the upper portion of a radial tire, including the performed casing, and mold in which the belt structure and tread are molded and vulcanized onto the tire casing.

With reference to Fig. 1 of the drawing, there is shown a radial tire 5 which essentially comprises conventional components of an innerliner 6; a single, or plurality of carcass plies 7, 8 reinforced with radially oriented parallel cords composed of rayon, nylon, polyester, aramid, or steel; a belt structure 9 for annularly reinforcing the radial tire 5, the belt structure composed of a plurality of belt plies 10, 11 which are in superimposed relation and which are reinforced by parallel cords composed of rayon, nylon, polyester, glass, aramid, or steel; and a tread 12 and pair of sidewalls 13, 14 surrounding the carcass plies 7, 8 and termi nating at a pair of inextensible annular beads 15, 16. A narrow, inextensible band 17 is centrally disposed around the radial tire 5 intermediate the belt structure 9 and radially outermost carcass ply 8.

The belt plies 10, 11, in the case of larger tires for uucks, for example, are reinforced with parallel aramid or metal cords that are disposed at similar angles in the broad range of from 0 to 90 degrees measured relative r.o a plane containing the mid-circumferential centerline of the tread 12, when the tire is molded, vulcanized, and uninfiated, such plane being hereinafter referred to as the centerplane, and in the narrower preferred range of from 15 to 80 degrees relative to the centerplane. The reinforcement cords of the successive belt plies 10, 11 extend in different directions from the centerplane, but at similar angles, although in some cases thc cord angle can vary from ply to ply. In the case of passenger tires, the reinforcement cords of the belt plies 10, 11 are disposed at angles in the broad range of 0 to 30 degrees and in the narrower, preferred range of 15 to 26 degrees relative to the centerplane. The reinforcement cords of the carcass plies 7, 8 are radially oriented, i.e. disposed at angles in the range of from 75 to 90 degrees measured relative to the centerplane.

A pair of rubber wedge strips 18, 19 are provided to transversely flatten the belt structure 9 so that it is in cylindrical relation about the center axis of the radial tire 5. The radial tire 5 is mounted on a conventional wheel rim 20.

With reference to Fig. 2, there is shown a beltless radial tire casing 21 which is utilized in the formation of the radial tire 5, as shown in Fig. 1. The tire casing 21 contains essentially all of the components of the radial tire 5 with the exception of the belt structure 9 and tread 12. The tire casing 21 can be formed without the sidewalls 13, 14 and undertread 22. However, it has been found more desirable to mold the tire casing 21 with these particular components. Thus, it can be appreciated that che radial tire 5 is almost completely molded and vulcanized except for the belt structure 9 and tread 12.

The unvulcanized tire casing 21 is conventionally built, as by the flat band method, after which it is placed in a conventional mold 23 where the tire casing 21 is molded and vulcanized. The outer peripheral surface 24 of the tire casing 21 can be molded smooth or with circumferential grooves which provide a mechanical innerlock of the later applied tread 12 with the preformed tire casing 21. The overall diameter D of the tire casing 21 can be easily computed for any given tire. This information is necessary, since it is important to restrict the tire casing to this particular diameter D for receipt of the later applied un vulcanized belt structure 9 and tread 12, so that the overall diameter of the finished tire will be essentially the same as that of a similarly sized tire which is conventionally molded and vulcanized in a mold.

After the tire casing 21 is completely molded and vulcanized and removed from the mold 23, it is ready for receipt of the belt structure 9 and tread 12 which can be accomplished in a number of ways. For example, the preformed tire casing 21 is mounted on the wheel rim 20 and inflated to the desired diameter D. The narrow restrictor band 17 is centrally disposed around the smooth outer peripheral surface 24 which is usually roughened slightly to enhance the bonding of the belt structure 9 and tread 12 to the tire casing 21. The narrow restrictor band 17, is designed so that it will prevent radial expansion of the tire casing 21 beyond diameter D without adversely affecting the operational characteristics of the belt structure 9. It can be appreciated that the width of the restrictor band 17 naturally depends on the size of the radial tire 5. It is good to maintain the width of the restrictor band 17 in the range of from 5 to 15 percent of the section diameter SD of the tire 5. A one-inch wide restrictor band 17 was found especially suitable for a size 10:0920 tire. The restrictor band 17 is composed of inextensible cords composed of material such as glass fibers, metal, or aramid.

The cords are parallel and extend longitudinally of the resuictor band 17. The ends of the restrictor band 17 are usually overlapped about 1 to 4 inches rather than being abutted. A smaller width restrictor band 17, e.g. one-half inch, can be spirally wound twice around the outer peripheral surface 24 of the tire casing 21 to form, for example, the oneinch wide restrictor band 17 used in the popular size tire indicated above. Thus, the restrictor band 17 can be made in a number of ways, so long as it is kept narrow enough not to adversely affect the operational characteristics of the belt structure 9.

The belt structure 9 is always unvulcanized when applied to the tire casing 21, but the tread 12, although usually composed of unvulcanized rubber material, can be a previously molded and vulcanized tread, in which case conventional adhesives are used to increase the bond between the preformed tread 12 and tire casing 21. When using a precured tread, it is advantageous to use the so-called "hot" process of permanently bonding the precured tread and belt structure to the tire casing, i.e. heating the assembly of the preformed tire casing 21 and tread 12 and unvulcanized components of belt structure 9, restrictor band 17, and bonding layer conventionally used when precured treads are used, in an atmosphere of steam or air which is heated to a temperature of 200 degrees F. or more, as distinguished from the so-called "cold" process, where the precured tread is bonded to a tire casing at room, or slightly elevated room temeperatures.

As best seen in Fig. 3, the assembly of a preformed tire casing 21, unvulcanized, partially vulcanized, or vulcanized restrictor band 17, unvulcanized belt structure 9, and unvulcanized tread 25 are positioned within another mold 26 where the unvulcanized components are vulcanized and a pattern of ribs and grooves are molded into the outer surface 27 of the tread 25. The use of a restrictor band 17 in this situation is particularly advantageous, because it keeps the beltless tire casing 21 from ballooning out into the mold 26, whereby the finish molded and vulcanized tire becomes distorted from a desired shape.

An alternate method of using a restrictor band 17 in the building of a radial tire, is to initially build the restrictor band 17 into the beltless tire casing 21. In such a method the unvulcanized tire casing 21 is toroidally shaped to receive an unvulcanized restrictor band 17 which, depending on the final shaping of the tire casing 21, has reinforcement cords disposed at angles in the range of from zero to 10 degrees relative to the centerplane. Usually, even a toroidally shaped tire casing 21 requires further expansion during the molding and vulcanization process. Therefore, the cords may be at a slight angle, relative to the centerplane, to allow further limited expansion of the tire casing 21 necessary to the complete formation of the tire casing 21. Another way of accomplishing this is to use cords, such as rayon, which are circumferentially oriented around the tire casing 21 and which are slightly expansible or elongatable.

Thus, there has been provided a method of building a radial tire of a preformed tire casing to which is later added the belt structure and tread.

WHAT WE CLAIM iS:- 1. A method of building a radial tire, comprising the steps of: (a) providing a beltless tire casing including: (I) at least one carcass ply reinforced with radially oriented (as herein defined) cords, and (II) a pair of inextensible bead cores secured to said carcass ply; (b) positioning an unvulcanized belt structure comprising at least one belt ply of unvulcanized rubber material, reinforced with tire cords, circumferentially around the outer periphery of the shaped beltless tire casing, and, before positioning the belt structure, positioning a restrictor band which is separate from and narrow relative to the belt structure circumferentially about the outer periphery of the beltless tire casing to lie between the belt structure and the tire casing; (c) placing a tread circumferentially around the belt structure positioned on the beltless tire casing; and (d) vulcanizing any unvulcanized components of the tire, including the belt structure, the restrictor band serving to prevent expansion of the beltless tire casing beyond the diameter it takes up when the tire is vulcanized and molded.

2. A method according to claim 1, wherein the restrictor band is composed of rubber material reinforced with cords which are disposed at angles in the range of from zero to 10 degrees relative to the centerplane.

3. A method according to claim 2, which includes molding and vulcanizing the restrictor band into the beltless tire casing during the molding and vulcanization thereof, prior to the receipt thereby of the unvulcanized belt struc ture and tread.

4. A method according to claim 3, which includes toroidally shaping the unvulcanized tire casing to a predetermined desired dia meter to receive the restrictor band.

5. A method according to claim 2, wherein the tread is unvulcanized, prior to positioning on the tire casing.

6. A method according to claim 1 or claim 2, wherein the tread is previously molded and vulcanized, prior to positioning on the tire casing.

7. A method according to claim 2, wherein the restrictor band is reinforced with cords which extend circumferentially of the tire and which are composed of materials of the group of glass, metal and aramid.

8. A method according to claim 1 or claim 2 wherein the radially oriented cords of the said at least one carcass ply are composed of material of the group of rayon, nylon, poly ester, glass, aramid, and metal, and the reinforcement cords of the belt structure are composed of material of the group of glass, aramid, and metal.

9. A radial tire built by a method according to claim 1 and comprising: (a) at least one carcass ply reinforced with radially oriented (as herein defined) reinforcement cords; (b) a tread and pair of sidewalls surrounding the said at least one carcass ply, each sidewall having, at its edge, an inextensible annular bead; (c) a belt structure positioned between the tread and the or the radially outermost carcass ply of the tire; and (d) a restrictor band of substantially inextensible cords interposed between the belt structure and the or the radially outermost carcass ply of the tire, the restrictor band being separate from the belt structure and narrow relative to the belt suucture.

10. A radial tire according to claim 9, wherein the belt structure includes a plurality of belt plies which are reinforced with tire cords that are disposed at angles in the range of from zero to 90 degrees relative to the center-plane.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. elevated room temeperatures. As best seen in Fig. 3, the assembly of a preformed tire casing 21, unvulcanized, partially vulcanized, or vulcanized restrictor band 17, unvulcanized belt structure 9, and unvulcanized tread 25 are positioned within another mold 26 where the unvulcanized components are vulcanized and a pattern of ribs and grooves are molded into the outer surface 27 of the tread 25. The use of a restrictor band 17 in this situation is particularly advantageous, because it keeps the beltless tire casing 21 from ballooning out into the mold 26, whereby the finish molded and vulcanized tire becomes distorted from a desired shape. An alternate method of using a restrictor band 17 in the building of a radial tire, is to initially build the restrictor band 17 into the beltless tire casing 21. In such a method the unvulcanized tire casing 21 is toroidally shaped to receive an unvulcanized restrictor band 17 which, depending on the final shaping of the tire casing 21, has reinforcement cords disposed at angles in the range of from zero to 10 degrees relative to the centerplane. Usually, even a toroidally shaped tire casing 21 requires further expansion during the molding and vulcanization process. Therefore, the cords may be at a slight angle, relative to the centerplane, to allow further limited expansion of the tire casing 21 necessary to the complete formation of the tire casing 21. Another way of accomplishing this is to use cords, such as rayon, which are circumferentially oriented around the tire casing 21 and which are slightly expansible or elongatable. Thus, there has been provided a method of building a radial tire of a preformed tire casing to which is later added the belt structure and tread. WHAT WE CLAIM iS:-

1. A method of building a radial tire, comprising the steps of: (a) providing a beltless tire casing including: (I) at least one carcass ply reinforced with radially oriented (as herein defined) cords, and (II) a pair of inextensible bead cores secured to said carcass ply; (b) positioning an unvulcanized belt structure comprising at least one belt ply of unvulcanized rubber material, reinforced with tire cords, circumferentially around the outer periphery of the shaped beltless tire casing, and, before positioning the belt structure, positioning a restrictor band which is separate from and narrow relative to the belt structure circumferentially about the outer periphery of the beltless tire casing to lie between the belt structure and the tire casing; (c) placing a tread circumferentially around the belt structure positioned on the beltless tire casing; and (d) vulcanizing any unvulcanized components of the tire, including the belt structure, the restrictor band serving to prevent expansion of the beltless tire casing beyond the diameter it takes up when the tire is vulcanized and molded.

11. A tire according to claim 10, wherein

the reinforcement cords of the belt plies are disposed at angles in the range of from 16 degrees to 26 degrees, relative to the said plane.

12. A radial tire according to any of claims 9 to 11 wherein the width of the restrictor band is in the range of 5 to 15 percent of the section diameter of the tire.

13. A method of building a radial tire sub stantially as hereinbefore described with reference to the accompanying drawings.

14. A radial tire substantially as hereinbefore described with reference to the accompanying drawings.