DE2235980A1 - PROCESS FOR MANUFACTURING OR TREADING TIRES - Google Patents

Description

DR ,. MÜLLER-BORE DIPL-PHYS. DR. MANITZ DIPL ..- CHEM. DR. DEUFEL DIPL.-ING. PINSTERWALD dipl.-ing. GRÄMKOW PATENT LAWYERS 2235980

Munich, the ** ■ JWU Mafc / ri - D 134-9

Dunlop ltd of Dunlop House Ryder Street, St, James ¹ s, London, SW 1 / ENSLAITD

Process for making or resurfacing

tire

The invention relates to a method for producing or Retreading of pneumatic tires.

According to the invention, a method for production is provided an at least partially vulcanized tread ring for a pneumatic tire, in which the rubber, which the profile or to form the tread of a tire, formed in the shape of a ring at a pressure and at least partially vulcanized, which is higher than the pressure normally used when molding and vulcanizing unvulcanized, is used in the usual way built tire. In tire manufacture, the molded and at least preferred is preferred partially vulcanized tread ring applied to a cambered unvulcanized tire carcass and the combination

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of ring and carcass together, for example in one form vulcanized. With new rubber lining or soling or retreading of a worn tire, the molded and at least partially vulcanized tread ring is placed on a roughened and loosened (solutioned) substructure sewn or stapled and the arrangement or combination formed in this way is then subjected to a vulcanization step, for example in an autoclave.

The tread ring is preferably formed at a pressure in excess of 35 kg / sq cm (500 psi), for example 100 kg / sq cm (1500 psi); The high temperatures are Dami used to produce a thick tire tread ring which has an increased wear and abrasion resistance to molded at lower pressures tread DAEU. The tread ring can be substantially completely vulcanized during molding.

The inventive method can be used for Production of radial, diagonal or belt-diagonal tires (belted bias tires) and is particularly suitable for the production of tires that have reinforcement in the Tread ring, for example include a breaker assembly.

In the manufacture or retreading of tires with a breaker arrangement or other tread reinforcement according to According to the invention, the initially prepared tread ring comprises the tread rubber and the breaker assembly. Such a tread ring is at a high pressure, for example in the order of 100 to 140 kg / icm (1,500-2,000 p.s.i.) formed on a core or bead and at least partially vulanized, the device, for example

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a channel, which enables precise positioning of the Breaker arrangement facilitated. The core indicates "preferred a contractible construction or segment construction to allow removal of the tread ring.

During tire manufacture, the shaped and at least partially vulcanized tread ring is then cambered onto a cambered one unvulcanized carcass applied · This step is preferred by simultaneous crowning or · shaping and expanding the radial or diagonal carcass into the tread ring

A good bond or good adhesion between the To ensure the tread ring and the unvulcanized carcass, the tread ring is preferred on its inner circumference roughened and loosened before it is applied to the carcass. In particular, it is advantageous in the preparation of a tire in which the tread ring comprises a breakoscan assembly The tire carcass has a rubber ply arranged, which acts as a breaker cushion, the rubber for a effective cross-linkage with the at least partially vulcanized tread during the final Vulcanization stage is mixed or composed in a suitable manner.

The final vulcanization stage for vulcanizing the tire carcass to the tread ring can be carried out in one be performed flat shape, since further shaping of the tread ring is not required and the tread ringj in almost all circumstances, it will do what is necessary Tread pattern or profile is provided on its outer surface. Using a flat

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Mold allows the profiled ring to be easily removed from the mold compared to removal a tire provided with a tread pattern from a Shape with a profile-tread-shape matrix.

When soling or retreading, the formed and at least partially vulcanized tread is then roughened on and loosened tire casing from which the old breaker has been removed and the formed Arrangement or combination is a vulcanization, for example subjected in an autoclave. To do this, the diameter of the substructure must be reduced, to be inserted into the tread ring and then expanded to substantially its original shape.

As a result, it is possible with the method according to the invention it is the use of a contractible core or segment core in molding and vulcanizing a tread ring with a breaker arrangement to form a belt tread tire (braced tread tire) without the use of the expensive Segment shape normally required to allow removal of the tire from the mold. Tread uniformity can thus also be more easily obtained.

The method according to the invention makes it possible to achieve an increased accuracy of the running surface thickness, in particular in the case of large Tires, and also with tires with breaker arrangements to obtain a better centralization of the breaker. The application a tread ring also means a reduction the number of seams in the tire.

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If desired, the tread ring can consist of an injection-molded

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or extruded rubber strips or such strips and, where appropriate, breaker layers are made from rubberized Öordware.

The running surface ring is preferably produced by transfer molding, a breaker arrangement, where it is used, is prearranged precisely and firmly in position on a core which is part of a Transfer mold forms. A mass of tread rubber is placed in the open mold and the The mold is closed under pressure, whereby the rubber is pressed under pressure into the mold cavity and thus the tread is molded on the breaker. - '

The invention is illustrated below with reference to the drawing, for example described; in this shows:

Fig. 1 is a chemical cross-sectional view of the exterior Part of a tire produced by the method according to the invention,

Figure 2 is a sectional view of an transfer molding apparatus showing the breaker assembly and the rubber compound shown in place with the form open are and

Figure 3 is a view similar to Figure 2 in which the mold is closed.

According to Fig. 1, the tire consists of a carcass 1 with a reinforcement 2 and a tread ring 3 »which consists of a tread M- , and a breaker arrangement 5 · The carcass 1 comprises a rubber breaker cushion 6, which is arranged under the breaker arrangement 5 is, the latter being off. three breakers

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layers 7 »8 and 9 is built up ·

This tire can be made from a "green or fresh" tire carcass which is molded on a crowning or injection device for a bring into contact with the inner circumference of the prepared tread ring carried coaxially around the carcass, and the whole The assembly can be vulcanized in a flat shape; or the tire can be in a retreading operation starting from a roughened and loosened, worn tire carcass which the prepared tread ring is tacked on and vulcanized in a flat mold or in an autoclave. The retreading process removes any additional rubber that is on the side walls, for example or shoulders, at the same high pressure that is used to form the treads in Strip or ring shape at least partially vulcanized and molded and attached to the carcass with the tread ring.

The tread ring 3 of the tire 1 has been manufactured by means of transfer molding.

2 and 3, the transfer molding apparatus includes a pair of mold halves 10 and 11 which carry tread molding surfaces 12 and 13. The mold half 10 includes a flange 14 which fits snugly around the peripheral surface 15 of the mold half 11 so that the mold halves 10 and 11 can be pushed apart to a distance equal to the length of the flange 14 to provide an enlarged cavity. in which a rubber compound can be arranged.

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The inner surface 17 of the flange 14 tapers slightly, so that when the mold halves 1o and 11 to each other are moved, the seal between the surfaces 15 and 17 is increased to prevent escape of rubber from the mass 16 to prevent this in the form pressurized. is. .

The radially inner surface of the mold cavity is of a segment toroidal core 18 is formed, the one radially has outer surface 19 which is designed to receive and hold a breaker arrangement 5. The segments of the core are assembled on and supported by a circular member 20; the mold halves and the individual segments of the core are each provided with cavities 21 for the passage of a heating or cooling fluid intended*

In operation, a breaker assembly 5 is placed on the outer surface 19 of the segment core 18 and the core is placed in position against the mold half 10. A ring mass of rubber sufficient to fill the mold cavity and spue cavities 22 is placed within the flange 14 of the mold half 10 and the mold half 11 is then pushed down against the rubber mass with a ram pressure of about ^L \ ^ 0 tons (450 tons), creating a molding pressure on the order of 100 to 140 kg / sq cm (1,500-2,000 psi). As the rubber is deformed, the mold half 11 moves closer to the mold half 10, the seal between surfaces 15 and 17 becoming tighter and the rubber being pressed into the mold cavity and molded to form the tread portion of the tread ring 5.

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When the forming step is complete, will the temperature of the tread ring is kept at an elevated temperature in order to partially vulcanize the rubber. When the rubber compound is of the type described below, the tread ring can, for example for 30 min. at 150 ° C, 20 min. at 160 ° C or 15 min. be held at 170 ° 0.

An example of the type of rubber compound used in the The transfer molding operation can be used to form the tread 4 is given in Table I below.

TABLE I. Parts by weight ■ · oil-extended styrene / butadiene 75.00 Rubber (1712) 25.00 oil-extended polybutadiene 1.75 sulfur 1.00 Cyclohexylbenzulfenamide 0.45 N-nitrosodiphenylamine 1.00 Stearic acid 7.50 Process Oil 1.50 Isopropyl-p-phenylenediamine 1.00 Paraffin wax 3.50 zinc oxide 52.50 ISAF soot 170.20

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Claims (1)

Claims 1. A method for producing an at least partially vulcanized Tread for a pneumatic tire, characterized in that rubber, which the tread, before a tire is supposed to form, in the shape of a ring s is molded and at least partially vulcanized at a pressure higher than the normal pressure in the molding and vulcanization of unvulcanized, in Usually built or wound tires is used. \ 2. The method according to claim 1, characterized in that the molding pressure is higher than about 35 kg / sq cm *, (500 psi) ge.kennzeich- i net. • 3 · Method according to claim 1, characterized in that g e k en η ze ic h - net that the molding pressure is in the order of magnitude from \ to 140 kg / sqcm (1500-2000 psi). I 4. A method according to any one of the preceding claims, characterized j in that the ring is formed in a ring-shaped cavity by {transfer molding (transfer molding). \ 5 · Method according to one of the preceding claims, characterized in that the running surface ring * a tread pattern is imprinted during the forming process. - 10 - 20988571039 6. The method according to any one of the preceding claims, characterized in that a gain in the Tread ring is provided. 7. The method according to claim 6, characterized in that it pays off, that the reinforcement comprises a breaker arrangement θ. Method according to claim 6 or 7 »thereby g e k β η η ζ ei c h η θ t that the hanging is formed on a core, the means for an accurate positioning of the reinforcement and that the reinforcement is placed on the core prior to forming the ring. 9. The method according to claim 6 or 7 »characterized in that the ring is formed on a core, which has a channel in which the reinforcement can be precisely arranged, and that the reinforcement in the channel placed prior to molding the tire. 10. The method according to any one of the preceding claims, characterized in that the tread ring during of molding is substantially fully vulcanized. 11. A method for producing a pneumatic tire, characterized in that a tread ring, which means a method according to any one of the preceding claims has been produced to a cambered or shaped unvulcanized tire carcass is applied and that the ring and the carcass are vulcanized together. 12. A method for retreading a pneumatic tire, characterized in that that a tread ring which is produced by means of a method according to one of claims 1 to 10 - 11 209885/1039 223598Q is attached to a roughened, worn tire casing, and then the assembly so formed is subjected to a vulcanization stage. A method for retreading a pneumatic tire according to claim 12, characterized in that any additional rubber required on the substructure is molded at the same pressure, which is used for the molding of the tread ring, that the additional rubber in strip or ring form and that the additional rubber is adhered to the substructure with the tread ring. 209885/1039 Blank page