Systems and methods for forming refurbished tires using flat back tread

Abstract

The present invention provides a retreaded tire and a manufacturing method thereof. A tire is retreaded using a pre-cured tread rubber, wherein the pre-cured tread rubber has one or more tread grooves with a compliant groove base rubber thickness on a smooth back and front sides. The grooves on the pre-cured tread rubber are aligned with the grooves in the tire body and conform to the shape of the tire body grooves during vulcanization. The tire tread depth is greater than the original tire tread depth of the pre-cured tread rubber, thereby increasing the wear volume of the tire tread.

Description

[0001] This application is a divisional application of the invention patent application with application number 201480073117.0 and name “System and method for forming a retreaded tire using a flatback tread”. Background Art

[0002] The present disclosure relates generally to retreading of tires, and more particularly, to systems and methods for retreading tires and manufacturing retreaded tires.

[0003] When a tire is worn, the worn tread can be replaced using a process known as retreading. This retreading process can include a mechanical grinding process to remove the worn tire tread from the carcass. The grinding process allows one to grind the carcass to a desired size, shape, and texture. The tire tread can then be applied to the polished carcass. For example, a pre-cured tire tread having a desired tread design on the outer surface can be applied or positioned to the polished carcass. An adhesive layer (such as an uncured rubber compound) can be applied between the tread and the carcass to promote adhesion between the tread and the carcass. The assembly including the carcass and the tread can then be vulcanized or hardened in a vulcanization chamber (such as an autoclave). Thus, a retreaded tire can be produced.

[0004] The retreading method involves bonding a tread to a carcass that is either buffed flat or has a continuous cambered profile. The tread comprises a front face that contacts the ground and provides traction, and a back face that may be bonded to the carcass. As part of the tread design, grooves may be provided on the front face of the tread.

[0005] The volume of tire tread required to produce a retreaded tire with sufficient tread groove depth is costly. Therefore, it is desirable to reduce the volume of material required for the tire tread while maintaining or even improving the wear volume of the tire tread (e.g., the useful volume of tread material that can be worn until the depth of the exposed tread grooves is reduced to the point where the tire needs to be scrapped and discarded or thrown away). Therefore, it is desirable to provide a retreaded tire with an optimal tread wear volume and a compliant tread groove depth, as well as a system and method for manufacturing a retreaded tire with an optimal tread wear volume and a compliant tread groove depth. Summary of the invention

[0006] The present disclosure generally relates to tread retreading of tires, and more specifically, to systems and methods for retreading tires and manufacturing retreaded tires. For example, in certain embodiments, systems and methods for retreading tires using a pre-cured tread rubber having a substantially smooth back side and one or more tread grooves on the front side are provided. The grooves in the pre-cured tread rubber are aligned with the grooves in the carcass, and during the vulcanization process, the substantially smooth back side can conform to the shape of the carcass grooves to form new grooves that act synergistically. The retreaded tire advantageously has a compliant groove base rubber thickness, and its tire tread depth is greater than the original tire tread depth of the pre-cured tread rubber, thereby increasing the wear volume of the tire tread.

[0007] According to one aspect, a method for retreading a tire is provided. The method may include providing a carcass having a carcass profile with at least one carcass groove, the at least one carcass groove having a carcass groove depth and a carcass groove shape; and the method includes providing a tire tread, the tire tread having a substantially smooth profile on the back side and at least one tread groove on the front side, the at least one tread groove having an initial tread groove depth. The method may also include aligning the tire tread to the carcass to produce a tire assembly, wherein the substantially smooth profile on the back side of the tire tread faces the carcass, and wherein the at least one tread groove on the front side of the tire tread is aligned with the at least one carcass groove; and the method includes vulcanizing the tire assembly under pressure so that the back side of the tire tread conforms to at least a portion of the carcass profile, wherein the at least one tread groove conforms to the carcass groove depth and the carcass groove shape so that the final depth of the tread groove is greater than the initial tread groove depth.

[0008] According to one aspect, a method for retreading a tire is provided. The method may include providing a carcass having a carcass profile with at least one carcass groove having a carcass groove depth and a carcass groove shape; and the method includes providing a tire tread having at least one tread groove on a front side of the tire tread having an initial tread groove depth and a back side having a substantially smooth profile in an area near the bottom of the at least one tread groove. The method may also include aligning the tire tread to the carcass to produce a tire assembly, wherein the substantially smooth profile on the back side of the tire tread faces the carcass, and wherein the at least one tread groove on the front side of the tire tread is aligned with the at least one carcass groove; and the method includes vulcanizing the tire assembly under pressure so that the back side of the tire tread conforms to at least a portion of the carcass profile, wherein the at least one tread groove conforms to the carcass groove depth and the carcass groove shape so that the final depth of the tread groove is greater than the initial tread groove depth.

[0009] According to another aspect, a retreaded tire is provided. The retreaded tire may include a carcass having a sidewall, and a tire tread vulcanized to the carcass, the tire tread having a final tread groove depth greater than an initial tire tread groove depth, wherein the tire tread has been connected to the carcass by vulcanizing the tire assembly at high pressure and temperature. When vulcanized, the assembly may include at least one carcass component and a tire tread component, the tire tread component having a substantially smooth profile on a back side and at least one tread groove on a forward side, the at least one tread groove having an initial tire tread groove depth, and the carcass component having a carcass profile having at least one carcass groove having a carcass groove depth, and wherein the substantially smooth back side of the tire tread component faces the carcass component, and wherein the at least one tread groove is aligned with the at least one carcass groove.

[0010] According to yet another aspect, a system for retreading a carcass is provided. The system may include a container, a pressure source operable to increase the pressure within the container, a heat source operable to increase the temperature within the container, and a tire assembly. The tire assembly may include a tire tread and a carcass, the tire tread having a substantially smooth back side and at least one tread groove on a front side having an initial tread groove depth; a carcass profile of the carcass having at least one carcass groove, the at least one carcass groove having a carcass groove depth. In operation, the tire tread may be positioned on the carcass so that the substantially smooth back side of the tire tread faces the carcass, and wherein the at least one tread groove is aligned with the at least one carcass groove. The tire tread may be configured so that when the precured tire assembly is provided into the container and the pressure and temperature are increased, the back side of the tread will conform to the carcass profile and the carcass groove shape in a manner such that the final depth of the tread groove is greater than the initial tread groove depth.

[0011] Other features and advantages of the present disclosure will be appreciated by referring to the remainder of this specification, including the drawings and claims. Additional features and advantages of the present disclosure, as well as the structure and operation of various embodiments of the present disclosure are described in detail below with reference to the drawings. In the drawings, similar reference numerals represent identical or functionally similar elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A partial cross-sectional view of separate components of a tire assembly is shown according to one embodiment.

[0013] Figure 2 A partial cross-sectional view of a tire assembly according to one embodiment before vulcanization is shown.

[0014] Figure 3 According to one embodiment, Figure 2A partial cross-sectional view of a retreaded tire obtained after the tire assembly is vulcanized.

[0015] Figure 4 A method of retreading a tire according to one embodiment is shown. DETAILED DESCRIPTION

[0016] Retreaded tires and methods of forming retreaded tires are described herein. According to certain exemplary embodiments, a tire is retreaded using a tread rubber having one or more tread grooves with a compliant groove base rubber thickness on a substantially smooth back and front side. The grooves on the tread rubber can be manipulated to align with the grooves in the carcass and can conform to the shape of the carcass grooves when vulcanized. The retreaded tire advantageously may have a compliant groove base rubber thickness and a groove depth greater than the original groove depth of the tread rubber, thereby increasing the wear volume of the tire tread. In some aspects, the tread rubber may be pre-vulcanized, while in other aspects, the tread rubber may be unvulcanized. In general, the present disclosure is applicable to any type of tread retreading method.

[0017] Figure 1 A partial cross-sectional view of separate components of a tire assembly 10 according to one embodiment is shown. The tire assembly 10 includes a tread 20 and a carcass 30. The carcass 30 includes a buffed front side 34 having one or more pre-formed grooves 35. The grooves 35 may include existing grooves in the carcass, or they may be formed during the buffing process. Although the grooves shown have a curved profile, it should be understood that other profiles are also available, such as rectangular, triangular, polygonal, etc. The carcass 30 typically also includes a wire ring that includes one or more wires or belts 33 embedded in the carcass. The tire tread 20 has a substantially smooth back side 22 and one or more tread grooves 25 on the front side 24. It should be understood that when discussing tire components (such as tire treads), the terms "face" and "side" are used interchangeably herein. Each tread groove 25 has an initial tread groove depth d i Similar to the carcass grooves, although the tread grooves are shown as having a curved profile, it should be understood that other profiles are also possible, such as rectangular, triangular, polygonal, etc. In addition, although the groove profiles are shown as coinciding (e.g., both are curved), the grooves may also be other combinations of profiles that are aligned with each other. As shown (not drawn to scale), the initial tread groove depth d i Less than the tread rubber depth or thickness d t , where d t -d i The difference is usually within approximately 1 / 32".

[0018] When there is more than one tread groove, each groove may have the same profile (cross-sectional shape and initial tread groove depth), or some or all of the tread grooves may have different profiles. In some aspects, the one or more tread grooves are circumferential grooves, such as circumferential grooves that run parallel to the centerline of the tire. The one or more tread grooves may include transverse tread grooves, such as grooves having a directional component of an angle between about 1° and 90° (completely perpendicular to the centerline) relative to the centerline of the tire. It should be understood that the profile of a particular tread groove may vary along the length of the groove.

[0019] Figure 2 A partial cross-sectional view of a tire assembly 10 according to one embodiment before vulcanization is shown. As shown, the tread 20 is positioned on the carcass 30 so that the substantially smooth back side 22 of the tread 20 faces the exposed front side of the carcass 30, and one or more tread grooves 25 are aligned with one or more carcass grooves 35 in the polished carcass 30. For example, the centerline of the groove having a symmetrical profile is substantially aligned with the centerline of the symmetrical carcass groove, as shown (dashed line). A bonding layer (not shown) may be provided between the tire tread 20 and the carcass 30. As is well known, the bonding layer may include a rubber compound or a glue layer that promotes bonding of the tread to the carcass. Examples of useful materials for the bonding layer include unvulcanized rubber compounds and mixtures thereof. As shown in FIG. Figure 2 As shown, when tread 20 is positioned and aligned, there are one or more gaps or spaces between back surface 22 and tread 20 and grooves 35 defined by the carcass grooves.

[0020] The substantially smooth back side includes a back side surface having a certain roughness or grain size, which is determined by the rubber compound used, the extrusion process used to form the tread rubber, and any pre-assembly processing. Generally speaking, when positioned on a flat surface, the entire back side 22 can be flat (for example, compared to the carcass including the grooves), however, due to the flexibility of the rubber material generally used, the substantially smooth back side will bend to adapt to a curved surface, such as a curved carcass contour. The substantially smooth back side generally has a smooth and continuous surface appearance over the entire tread contour, or in an area near the bottom of at least one tread groove. The substantially smooth area preferably does not contain protrusions extending from the back side, such as pre-formed shapes or discontinuous surface features on the back side near the tread grooves. It should be understood that a substantially smooth back side does not exclude intentional protrusions or grooves in the back side that do not interfere with the alignment of the tread grooves and the carcass grooves, for example, alignment features or protrusions that may be present away from the groove alignment area, the alignment features or protrusions extending outwardly or inwardly from the back side 22, and may be positioned to facilitate attachment or alignment of the tire tread to the carcass by closely engaging complementary grooves or features on the carcass. Similarly, in addition to the portion aligned with the grooves in the carcass, other profiles may be provided, such as that described in U.S. Patent No. 5,277,727, which is incorporated herein by reference. Thus, the substantially smooth profile of the back side of the tread may include a surface profile that is substantially flat and without discontinuities, and it may include a curved surface without discontinuities, or it may include a flat or curved surface profile with discontinuities in an area away from the tread grooves that conform to the carcass grooves.

[0021] As described in detail below, Figure 2 The carcass assembly 10 shown in FIG. 1 is subjected to a vulcanization process. Figure 3 According to one embodiment, Figure 2 The retreaded tire 100 is a partial cross-sectional view of the tire assembly 10 obtained after vulcanization. The retreaded tire 100 includes a tire having a final tread groove depth d f The tread groove has a depth greater than the initial groove depth d of the tire tread 20. i

[0022] During the vulcanization process, the bottom portion of the tread groove 22 conforms to the contour of the carcass groove 35. Due to the increase in pressure during vulcanization, the bottom portion of the tread groove undergoes negative deformation or distortion and moves downward into the carcass groove, increasing the tread groove depth; the thickness d t -d i The rubber material at the bottom of the tread groove can sometimes become thinner to a certain extent after reaching the Poisson's ratio, so that the tread groove depth is further increased.

[0023] The carcass groove depth can be any depth that is practical for a given particular application. In some aspects, for example, the desired carcass groove depth is less than about 5 / 32", such as between about 2 / 32" and about 5 / 32" for a standard truck tire. Optimally, the carcass groove depth is about 3 / 32". Depending on the depth d of the carcass groove, i , the final tread groove depth will increase relative to the initial tread groove depth. For example, when the carcass groove depth is about 3 / 32" deep, the tread groove depth may increase by about 2 / 32" or more, depending in part on various system parameters, such as the mechanical properties of the rubber components of the tire tread and the pressure and temperature when the tire assembly is vulcanized. For example, an initial tread groove depth of about 14 / 32" may increase to about 16 / 32". In the case of a carcass groove depth of about 3 / 32", a tread groove having an initial depth of between about 9 / 32" and about 26 / 32" may increase to between about 11 / 32" and about 28 / 32".

[0024] Various embodiments provide for increased wear volume of the tire tread. For example, when a flatback tire tread is cured to a flat carcass profile, the final tread groove depth will be substantially the same as the initial tread groove depth. Figure 3 As shown in FIG. , according to one embodiment, the final tread depth d f can extend below the carcass surface 24. Thus, the entire volume of the tread becomes part of the wear volume for the end user, i.e., the wear volume can be more efficient. Since the tire tread wears during use, the more efficient wear volume prolongs the service life of the tire tread, and in fact, when the tread is completely worn away and the groove base rubber thickness is left, the carcass rubber can be used as part of the wear volume. In this way, when compared to the existing process using a tread product with more tread volume but the same initial and final tread groove depth, a retreaded tire with the same or deeper tread groove depth can be produced using a substantially smooth back tread product (such as a flatback tread product) with reduced tread volume, which allows less carcass to be worn away in the tread retreading process, thereby saving material. In this way, the volume of material required to form the desired and usable tread groove depth in the retreaded tire is reduced, which in turn can save costs.

[0025] Figure 4A method 400 of retreading a tire according to one embodiment is shown. A carcass is provided in step 410. The provided carcass may be pre-ground to a desired shape, or it may be ground to remove any worn tread and have a desired shape. For example, the carcass may be ground to produce a carcass profile having at least one carcass groove having a specified groove depth and carcass groove shape. A tire tread is provided in step 420, the tire tread having a substantially smooth profile on the back side and a tread groove pattern having at least one tread groove on the front side. The at least one tread groove has an initial tread groove depth d i .

[0026] In step 430, the tire tread is placed or positioned on the carcass so that the substantially smooth profile on the back side of the tire tread faces the carcass and the at least one tread groove on the front side of the tire tread is aligned with the at least one carcass groove. Alignment step 430 produces a tire assembly. A step of applying or placing a bonding material between the carcass and the tire tread may be performed before vulcanization, such as before alignment step 430. The bonding material facilitates the attachment or bonding of the tire tread to the carcass during the vulcanization process. In step 440, the tire assembly is vulcanized. For example, the tire assembly is vulcanized under pressure in a chamber or container (such as an autoclave). The chamber or container may have a pressure source operable to regulate the pressure in the container, and a heat source operable to regulate the temperature in the container. Vulcanization generally includes increasing the pressure and temperature in the vulcanization chamber or container. Under the combined action of the vulcanization process, the back side of the tire tread conforms to the carcass profile. For example, the at least one tread groove conforms to the carcass groove depth and carcass groove shape so that the final depth d of the tread groove is f Greater than the initial tread groove depth d i .

[0027] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0028] In the context of describing embodiments (particularly in the context of the following claims), the terms "one", "a kind of", "the" and "at least one (kind)" used should be interpreted as covering both the singular and the plural, unless otherwise specified in this article or clearly conflicting with the context. The term "at least one" used followed by a list of one or more entries (e.g., "at least one of A and B") should be interpreted as meaning an entry (A or B) selected from the listed entries or any combination (A and B) of two or more of the listed entries, unless otherwise specified in this article or clearly conflicting with the context. The terms "include", "have", "include" and "contain" should be interpreted as open terms (i.e., meaning "including but not limited to"), unless otherwise specified. Unless otherwise specified in this article, the numerical ranges mentioned herein are only used as a shorthand representation method for referring to each individual value falling within the range, and each individual value is introduced into this specification as if it were recorded separately in this article. All methods or process steps described herein can be carried out in any suitable order, unless otherwise specified in this article or clearly conflicting with the context. Unless otherwise claimed, the use of any and all examples or exemplary language (e.g., "such as") provided herein is intended only to better illustrate the various embodiments and does not impose limitations on the scope of the various embodiments. No language in this specification should be construed as indicating that any non-claimed element is essential to the implementation of the various embodiments.

[0029] Exemplary embodiments are described herein, including the best mode known to the inventor. After reading the above description, variations of these embodiments may become apparent to those of ordinary skill in the art. The inventors expect that the skilled person can appropriately adopt such variations, and the inventors intend that these embodiments be implemented in a manner different from that specifically described herein. Therefore, as permitted by applicable law, all modifications and equivalents of the subject matter described in the appended claims are included herein. In addition, any combination of the above elements in all possible variations thereof is included herein, unless otherwise indicated herein or clearly conflicting with the context.

Claims

1. A retread tire assembly for forming a retread tire, comprising: A carcass comprising: side walls; and a flat carcass profile having at least one carcass groove having a carcass groove depth, A tire tread positioned on the carcass, the tire tread having: a front side having at least one tread groove having an initial tread groove depth; and a back side configured to bend between a first profile and a second profile, wherein the first profile is a back side profile of the tread before vulcanization, the first profile is substantially smooth, has a smooth and continuous surface profile on the first profile and has no discontinuities and no preformed shapes, and the second profile is a back side profile of the tread after pressure vulcanization, the bottom portion of the tread groove of the second profile is shaped to be received in the at least one carcass groove, and the smooth and continuous surface profile of the first profile is provided for the entire profile of the tire tread; and a bonding material disposed between the tire tread and the tire carcass; wherein the back side of the tire tread faces the carcass; wherein the at least one tread groove is aligned with the at least one carcass groove; wherein the back side of the tire tread is configured to conform to the flat carcass profile; and Wherein, when the back side bends from the first profile to the second profile, the at least one tread groove is configured to conform to the at least one carcass groove so that a final tread groove depth of the at least one tread groove is greater than the initial tread groove depth of the at least one tread groove.

2. The retreaded tire assembly according to claim 1, wherein: The tire tread is configured to be vulcanized to the carcass under pressure, The at least one tread groove has a tread groove bottom of an initial thickness, and The tread groove bottom of the at least one tread groove is configured to become thinner as the at least one tread groove is conformed to the shape of the at least one carcass groove such that a final thickness is less than the initial thickness.

3. The retreaded tire assembly of claim 1, wherein the carcass groove depth is less than 5 / 32", wherein the initial tread groove depth is between 9 / 32" and 26 / 32", and wherein the final tread groove depth is between 11 / 32" and 28 / 32".

4. The retreaded tire assembly of claim 1, wherein the initial tread groove depth is 14 / 32", and wherein the final tread groove depth is 16 / 32".

5. The retreaded tire assembly of claim 1, wherein the at least one carcass groove and the at least one tread groove are circumferential grooves, and wherein the tire tread includes at least one transverse groove.

6. A system for forming a retreaded tire, the system comprising: container; a pressure source operable to increase the pressure within the container; a heat source operable to increase the temperature within the container; as well as A tire assembly, comprising: a carcass having a carcass profile having at least one carcass groove, the at least one carcass groove having a carcass groove depth; and A tire tread having a back side and a front side on which at least one tread groove is formed, wherein the back side is configured to be curved between a first profile and a second profile, wherein the first profile is a profile of the back side of the tread before vulcanization, The first profile is substantially smooth, having a smooth and continuous surface profile, the smooth and continuous surface profile being free of discontinuities and preformed shapes, the second profile being a backside profile of the tread after pressure vulcanization, the bottom portion of the tread groove of the second profile being shaped to be received in the at least one carcass groove, the smooth and continuous surface profile of the first profile being provided for the entire profile of the tire tread, the at least one tread groove having an initial tread groove depth, and a bonding material disposed between the tire tread and the tire carcass; wherein the tire tread is positioned on the carcass such that a back side of the tire tread faces the carcass and the at least one tread groove is aligned with the at least one carcass groove; and Wherein the tire assembly is configured to be provided into the container, and the pressure source is manipulated to increase the pressure, and the heat source is manipulated to increase the temperature, the back side can be manipulated to conform to the carcass contour, so that the at least one tread groove is configured to conform to the shape of the at least one carcass groove in a manner such that a final depth of the at least one tread groove is greater than the initial tread groove depth of the at least one tread groove.

7. The system of claim 6, wherein the container is an autoclave.

8. The system of claim 6, wherein the carcass groove depth is less than 5 / 32", wherein the initial tread groove depth is between 9 / 32" and 26 / 32", and wherein the final depth of the at least one tread groove is between 11 / 32" and 28 / 32".

9. The system of claim 6, wherein the initial tread groove depth is 14 / 32", and wherein the final depth of the at least one tread groove is 16 / 32".

10. The system of claim 6, wherein the at least one carcass groove and the at least one tread groove are circumferential grooves, and wherein the tire tread includes at least one transverse groove.

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