WO1999008860A1

WO1999008860A1 - Method and apparatus for adhering precured tire components

Info

Publication number: WO1999008860A1
Application number: PCT/US1997/014381
Authority: WO
Inventors: David Thomas Reese; Frederick Forbes Vannan, Jr.
Original assignee: The Goodyear Tire And Rubber Company
Priority date: 1997-08-15
Filing date: 1997-08-15
Publication date: 1999-02-25
Also published as: AU4068997A

Abstract

Method and apparatus for curing a cushion layer (22) of heat curable material positioned on an outer surface (18) of a vulcanized tire body (14) covered by a vulcanized tread (26). The tire body is reinforced by a metal belt member (34) position on the outer surface. The metal belt member (34) is heated by subjection to an alternating magnetic induction field generated by one or more induction coils (46). The metal belt member (34) is utilized as a heater to radiate heat energy to the cushion layer (22) in order to heat and cure the cushion layer and thereby adhere the tread (26) to the tire body (14). The tire assembly may be rotated relative to the induction field in order to promote uniform heating of the metal belt member (34).

Description

METHOD AND APPARATUS FOR ADHERING PRECURED TIRE COMPONENTS Technical Field

This invention pertains to the art of methods and apparatuses for adhering precured tire components such as adhering a vulcanized tread to a vulcanized tire body.

Background Art

In the art it is known to provide a pre-vulcanized tire carcass with a vulcanized tread. The tire carcass may be a newly vulcanized carcass, or may be a tire carcass prepared for retreading. Generally, methods have been set forth which provide an unvulcanized strip of rubber or the like which functions as an adhesive layer between the carcass and the tread. An assembly may be prepared consisting of the adhesive layer positioned between an outer surface of the tire carcass and an inner surface of the tread. The assembly may then be completely encased in a molding apparatus and the entire assembly heated until vulcanization of the adhesive strip has occurred. Other methods for vulcanizing an adhesive strip positioned between a tire carcass and tread include heating the adhesive strip utilizing microwave energy. The tire carcass, adhesive strip, and tread assembly is retained in an envelope before being subjected to the microwave energy. In a similar method, disclosed in U.S. Patent No. 4,536,242, local heating of the edges of the adhesive strip is accomplished by positioning a material having a high dissipation factor for microwave energy near the edges of the adhesive strip.

The present invention provides methods and apparatuses for curing a cushion layer provided between a vulcanized tire body and a vulcanized tread which does not require the entire assembly to be heated to the necessary cure temperature. The objects of the invention can then be more quickly achieved with substantial energy savings. In addition, the tread is not subjected to over-curing by exposure to additional heating. The desired properties of the tread compound are thereby maintained. Disclosure of Invention

In accordance with the practice of the present invention, there is provided a new and improved method and apparatus for the application of a vulcanized tread to a vulcanized tire body.

More particularly, in accordance with the present invention, a method of curing a heat curable cushion layer positioned on an outer surface of a vulcanized tire body and covered by a vulcanized tread wherein the tire body is reinforced by a metal belt member positioned under the outer surface is provided. The method is characterized by the steps of retaining the tread on the tire body, placing induction means adjacent the tire body so that an induction field intersects the metal belt member when activated, and activating the induction means to heat the metal belt member to thereby heat and cure the cushion layer for adhering the tread to the outer surface. According to one aspect of the present invention, the induction means includes a single induction coil and the method is further characterized by the step of rotating the tire assembly so that the metal belt moves relative to the induction means to promote uniform heating of the metal belt.

According to a further aspect of the invention, the step of retaining the tread on the tire body includes wrapping the tire assembly with a shrinkable material. The step of retaining the tread on the tire body also supplies the necessary curing pressure at the cushion strip interface.

According to a further aspect of the invention, a method for applying a tread to a tire body comprising the steps of providing a heat curable cushion layer between an outer surface of a vulcanized tire body and a vulcanized tread and heating the cushion layer to a temperature sufficient to cure the cushion layer in order to adhere the tread to the tire body is provided. The method is characterized by the steps of providing a electrically conductive member beneath the outer surface of the tire body, providing inductive heating means for heating the electrically conductive member, activating the inductive heating means, and traversing the inductive heating means relative to the electrically conductive member to heat the electrically conductive member and thereby heat and cure the cushion layer.

According to a further aspect of the invention, a method of retreading a vulcanized tire body with a vulcanized tread utilizing a cushion layer of heat curable material positioned between an outer surface of the tire body and an inner surface of the tread and wherein the tire body comprises a metal reinforcing member positioned under the outer surface is provided. The method including the steps of forming a tire assembly by positioning the cushion layer over a crown area of the tire body, and positioning the tread over the cushion layer; applying a retaining member to the tire assembly to retain the tread in a proper relationship to the tire body; and, heating the cushion layer to sufficient temperature for sufficient time to cure the cushion layer and thereby adhere the tread to the tire body. The method is characterized by utilizing electrical induction means for heating the metal reinforcing member and thereby radiate heat to the cushion layer. According to a further aspect of the invention, an apparatus for curing a cushion layer of heat curable material within an associated tire assembly wherein the cushion layer of heat curable material is positioned between an outer surface of a vulcanized tire body and covered by a vulcanized tread and wherein the tire body is reinforced by a metal belt member positioned under the outer surface is provided. The apparatus is characterized by an electrical induction heating coil positioned relative to an outer surface of the associated tire assembly so that an induction field intersects the metal belt member when activated and thereby heats the metal belt member. The metal belt member radiates heat to the cushion layer to affect the cure.

One advantage of the present invention is the ability to quickly adhere a vulcanized tread to a vulcanized tire body.

Another advantage of the present invention is the utilization of an embedded metal reinforcement member as a heater for heating the heat curable cushion layer.

Another advantage of the present invention is that the entire tire assembly does not need to be brought to the vulcanization temperature in order to obtain the objects of the invention. Still other benefits and advantages of the invention will become apparent to those skilled in the art upon a reading and understanding of the following specification. Brief Description of Drawings

The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof and wherein:

Fig. 1 is a cross-sectional view of a portion of a tire assembly and one embodiment of electric induction heating means according to the invention.

Fig. 1A is an enlarged fragmentary view of the area identified as 1A in Fig. 1.

Fig. 2 is a side view of one embodiment of the present invention showing electric induction heating means surrounding a tire assembly.

Fig. 3 is a side view of yet another embodiment of the present invention showing a plurality of induction coils placed about a periphery of a tire assembly.

Fig. 4 is a side view of yet another embodiment of the present invention showing a single induction coil positioned relative to a tire assembly. Detailed Description of the Invention

Referring now to the drawings wherein the showings are for purposes of illustrating a preferred embodiment of the invention only and not for purposes of limiting the same, Figure 1 shows a tire assembly 10 including a vulcanized tire body 14 having an outer surface 18. Adjacent the outer surface 18 is a heat curable cushion layer 22 which functions to adhere the tread 26 to the tire body 14. The cushion layer 22 may comprise unvulcanized rubber, a heat activated adhesive or other material able to perform an adhesive function. Tread 26 is positioned so that an inner surface thereof 30 is immediately adjacent the cushion layer 22. In the practice of the present invention, the tire body 14 may be a newly formed tire carcass or may be a tire carcass from a retreading operation. The outer surface 18 of the tire body 14 is prepared for the treading operation by methods that are used and well known in the art. If the tire body 14 is a tire carcass from a retreading operating operation, the outer surface 18 would for example, be buffed or otherwise prepared for retreading.

An important element in the present invention is the presence of an electrically conductive member 34 beneath the outer surface 18 of the tire body 14. The electrically conductive member 34 is responsive to induction heating methods as will be explained further in this disclosure. The electrically conductive member 34 is thereby heated and radiates heat to the cushion layer 22 in order to cure the cushion layer 22 and thereby adhere the tread 26 to the tire body 14. In a preferred embodiment, the electrically conductive member 34 is a metal reinforcing member such as a steel belt or belt package as is well known in the art. Because the present invention utilizes the steel belt 34 which is a common element in tires the invention may be easily practiced without design changes in the tire body 14. Each of the components in the tire assembly 10 must be held in proper relative position during the entire induction heating process. Therefore, retaining means 38 for retaining the tire assembly 10 together during cure of the cushion layer 22 are provided For ease of illustration, retaining means 38 is shown only in Figure 1. In a preferred embodiment, the tire assembly 10 is retained by a shrinkable material or stressing belt to insure that the components of the tire assembly 10 are held in proper relative position during the entire induction heating process. The retaining means 38 must also provide pressure to the cushion layer 22 during the curing process to eliminate trapped air and porosity.

One preferred method of retaining the tire assembly together is by wrapping the tread surface 40 with damp nylon shrink wrap. The moisture is then driven off by the use of infrared lamps or heat guns (not shown). As the nylon dries, it contracts, putting pressure on the tread surface 40 and cushion layer 22. Other types of shrinkable material could be used in order to perform the same functions. Another preferred method of retaining the tire assembly together is the use of a non- ferrous clamping mechanism surrounding the tire assembly. The clamping mechanism could be formed of carbon fiber or reinforced fiberglass.

Yet another method of retaining the tire assembly together is the use of a pressurized chamber during the curing process.

In the practice of the present invention, an electric induction heating means 42 is provided which interacts with the electrically conductive member 34. Preferably, the heating means includes one or more induction coils 46. The induction coil 46 generates an alternating magnetic induction field when activated. The induction coil 46 is positioned relative to the tire assembly 10 so that the field intersects at least a portion of the electrically conductive member or steel belt 34. As the steel belt 34 encounters the induction field, heat is generated in the steel belt 34. The heated steel belt 34 radiates heat toward the cushion layer 22 and thereby vulcanizes the cushion layer 22 and adheres the tread 26 to the outer surface 18 of the tire body 14. Because the steel belt 34 is also a thermal conductor, heat is dissipated directly beneath the surface of the tire body 14. This heat radiates to the unvulcanized cushion layer 22. The tire assembly 10 may be rotated in order to uniformly heat the entire steel belt 34 and thereby cure the cushion layer 22. In a preferred embodiment, the steel belt 34 is heated to approximately 270° F to 300° F. The induction coil 46 may be a single-turn coil or multiple-turn coil, or of any design chosen with sound engineering principles. In one embodiment of the invention, shown in Figure 2, the electric induction heating means 42 includes a solenoid 50 which encircles the tire assembly 10. In this embodiment, the tire assembly 10 may be rotated, or it may remain stationary as the steel belt is heated. The size of the solenoid 50 as well as its contour, depends on the size of the tire assembly to be subjected to the induction process. Because the efficiency of the heating means is effected by distance, the electric induction heating means should be positioned as close to the tire assembly as possible. It is contemplated to maintain a gap, G, of between Va inch to ^lA inch.

In a further embodiment of the invention, shown in Figure 3, the induction heating means 42 comprises a plurality of induction coils 46 which may be essentially planar, or contoured to follow the outline of the tire assembly 10. The tire assembly 10 may be rotated with respect to the induction coils 46 or may remain stationary, depending on the number and placement of induction coils 46. It is important to ensure that the steel belt 34 is heated enough to affect the vulcanization of the cushion layer 22. It is also within the scope of the present invention to maintain the tire assembly 10 in a stationary position and traverse the induction coil(s) 46 with respect to the tire assembly 10.

In yet another embodiment of the invention, shown in Figure 4, a single contoured coil 46 may be positioned near the tire assembly 10. The tire assembly 10 may then be mounted onto rotational means and the tire assembly 10 rotated through the field generated by the induction coil 46. It is also within the scope of the present invention to maintain the tire assembly 10 in a stationary position and traverse the coil 46 relative to the tire assembly 10 in order to achieve the desired results.

The preferred embodiments of the invention have been described, hereinabove. It will be apparent to those skilled in the art that the above methods may incorporate changes and modifications without departing from the general scope of this invention. It is intended to include all such modifications and alterations in so far as they come within the scope of the appended claims or the equivalents thereof.

Having thus described the invention, it is now claimed:

Claims

1. A method of curing a cushion layer of heat curable material positioned on an outer surface of a vulcanized tire body and covered by a vulcanized tread wherein the tire body is reinforced by a metal belt member positioned under the outer surface, the method including the steps of preparing the outer surface for adhesion to said cushion layer, applying the uncured cushion layer to the outer surface and applying the vulcanized tread over said cushion layer to form a tire assembly; the method being characterized by the steps of: retaining the tread on the tire body; placing induction means adjacent the tire assembly so that an induction field intersects the metal belt member when activated; and, activating the induction means to heat the metal belt member to thereby heat and cure the cushion layer for adhering the tread to the outer surface.

2. The method of claim 1 wherein the method is further characterized by the steps of: mounting the tire assembly on rotational means for rotating the tire assembly; and, rotating the tire assembly so that the metal belt member moves relative to the induction field.

3. The method of claim 1 wherein the step of placing induction means adjacent the tire assembly includes: positioning a solenoid about a periphery of the tire assembly.

4. The method of claim 1 wherein the step of placing induction means adjacent the tire assembly includes: positioning a plurality of induction coils about a periphery of the tire assembly.

5. The method of claim 2 wherein the step of placing induction means adjacent the tire assembly includes: positioning a single induction coil in a predetermined position relative to the tire assembly.

6. The method of claim 1 wherein the step of retaining the tread on the tire body includes: wrapping the tire assembly with a shrinkable material.

7. The method of claim 1 wherein the step of retaining the tread on the tire body includes: utilizing a clamping mechanism formed of non-ferrous material.

8. The method of claim 1 wherein the step of retaining the tread on the tire body includes: positioning the tire assembly in a pressurized chamber.

9. The method of claim 1 further characterized by the step of: traversing the induction means relative to the metal belt member to promote uniform heating of the metal belt member.

10. The method of claim 1 wherein the heat curable material comprises unvulcanized rubber.

11. The method of claim 1 wherein the heat curable material comprises a heat activated adhesive.

12. A method for adhering a tread to a tire body comprising the steps of providing a heat curable cushion layer between an outer surface of a vulcanized tire body and a vulcanized tread and heating the cushion layer to a temperature sufficient to cure the cushion layer in order to adhere the tread to the tire body, the method characterized by the steps of: providing a electrically conductive member beneath the outer surface of the tire body; providing induction means for heating the electrically conductive member, the induction means being positioned relative to the tire body so that an induction field intersects the electrically conductive member when activated; activating the inductive heating means; and, traversing the inductive heating means relative to the electrically conductive member to heat the electrically conductive member and thereby heat the cushion layer.

13. The method of claim 12 wherein the electrically conductive member is a reinforcing steel belt.

14. The method of claim 12 wherein the induction means comprises a solenoid.

15. The method of claim 12 wherein the induction means comprises a plurality of induction coils.

16. The method of claim 12 wherein the induction means comprises a single induction coil and wherein the method is further characterized by the steps of: mounting the tire assembly on rotational means for rotating the tire assembly; and, rotating the tire assembly so that the metal belt member moves relative to the induction field.

17. The method of claim 12 wherein the heat curable material comprises unvulcanized rubber.

18. The method of claim 12 wherein the heat curable material comprises a heat activated adhesive.

19. A method of retreading a vulcanized tire body with a vulcanized tread utilizing a cushion layer of heat curable material positioned between an outer surface of the tire body and an inner surface of the tread and wherein the tire body comprises a metal reinforcing member positioned under the outer surface, the method including the steps of forming a tire assembly by positioning the cushion layer over a crown area of the tire body, and positioning the tread over the cushion layer; applying means for retaining the tread in a proper relationship to the tire body; and, heating the cushion layer to sufficient temperature for sufficient time to cure the cushion layer and thereby adhere the tread to the tire body, the method characterized by: utilizing electrical induction means for heating the metal reinforcing member and thereby radiate heat to the cushion layer.

20. An apparatus for curing a cushion layer of heat curable material within an associated tire assembly wherein the cushion layer of heat curable material is positioned between an outer surface of a vulcanized tire body and covered by a vulcanized tread and wherein the tire body is reinforced by a metal belt member positioned under the outer surface, the apparatus being characterized by: an electrical induction heating coil positioned relative to an outer surface of the associated tire assembly so that an induction field intersects the metal belt member when activated.

21. The apparatus of claim 20 further characterized by a plurality of electrical induction heating coils positioned relative to said outer surface of the tire assembly.

22. The apparatus of claim 20 wherein the electrical induction heating coil is a solenoid which surrounds the outer surface of the associated tire assembly.

23. The apparatus of claim 20 further comprising rotational means for rotating the associated tire assembly with respect to the electrical induction heating coil.