Tire manufacturing method

Abstract

A tire manufacturing method for obtaining a tire (10) including a tire body part (11) and a tread rubber part (12), the method comprising: a base tire preparation step (S101) for preparing a base tire (1) which is the tire body part of a used tire and which will become the tire body part (11); a molded tire assembly step (S102) for assembling a molded tire (4) by attaching a tread rubber (2), which will become a tread rubber part (12), to the outer peripheral side of the prepared base tire (1); a molded tire vulcanization step (S103) for vulcanizing the assembled molded tire (4); and a sipe forming step (S104) for forming a sipe (16) on the surface (5) of the tread of the vulcanized molded tire (4).

Description

Technical Field

[0001] The present disclosure relates to a tire manufacturing method.

[0002] This application claims priority based on Japanese Patent Application No. 2022-096887 filed in Japan on June 15, 2022, the entire contents of which are incorporated herein by reference. Background Art

[0003] It has been known for some time that sipes (thin cuts) are formed in the tread contact surface of a vulcanized tire using a tool such as a knife (see, for example, Patent Document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 60-240507 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] However, when sipes are formed on a new tire, it has been found that the sipe width may become wider due to the tire diameter growth during running, which may prevent the sipe from fully exerting its effects such as improving wear resistance, and the sipe bottom may also be more susceptible to cracks.

[0009] Therefore, an object of the present disclosure is to provide a tire manufacturing method for obtaining a tire in which the sipe width is less likely to vary.

[0010] Solutions for solving problems

[0011] The above problems will be solved by the following means.

[0012] (1) The tire manufacturing method disclosed in the present invention is:

[0013] A tire manufacturing method for obtaining a tire including a tire body portion and a tread rubber portion, characterized by comprising:

[0014] a base tire preparation step, wherein a base tire is prepared, the base tire being a tire body portion of a used tire and serving as the tire body portion;

[0015] a molded tire assembling step of assembling the molded tire by attaching a tread rubber to be the tread rubber portion to the outer peripheral side of the prepared base tire;

[0016] a molded tire vulcanization step, wherein the assembled molded tire is vulcanized; and

[0017] The sipe forming step includes forming sipes on the surface of the tread of the vulcanized molded tire.

[0018] Effects of the Invention

[0019] According to the present disclosure, it is possible to provide a tire manufacturing method for obtaining a tire in which the sipe width is less likely to vary. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] [ Figure 1 ] Figure 1 is a development view of a tread contact surface, illustrating an example of a tread pattern of a tire that can be obtained using the tire manufacturing method according to any embodiment of the present disclosure.

[0021] [ Figure 2 ] Figure 2 is a development view of a tread contact surface, illustrating another example of a tread pattern of a tire that can be obtained using the tire manufacturing method according to any embodiment of the present disclosure.

[0022] [ Figure 3 ] Figure 3 is a flowchart illustrating a tire manufacturing method according to one embodiment of the present disclosure.

[0023] [ Figure 4 ] Figure 4 is a diagram illustrating a tire manufacturing method according to an embodiment of the present disclosure, Figure 4 (a) shows a base tire that has been prepared in the base tire preparation step. Figure 4 (b) shows a tire that has been assembled in the tire assembly process. Figure 4 (c) shows the vulcanization process of the molded tire. Figure 4 (d) shows the sipe forming step. DETAILED DESCRIPTION

[0024] The tire manufacturing method disclosed in the present invention can be appropriately used as a manufacturing method for any type of pneumatic tire, such as TB tires (tires for trucks and buses), LT tires (tires for vans and small trucks, tires for small trucks and buses), OR tires (tires for construction and mining vehicles), and can be particularly well used as a manufacturing method for TB tires or LT tires.

[0025] Hereinafter, an embodiment of a tire manufacturing method according to the present disclosure will be described by way of example with reference to the accompanying drawings.

[0026] In the various drawings, the same components and parts are denoted by the same reference numerals.

[0027] In this specification, the term "tire circumferential direction" refers to the direction in which the tire rotates around its rotation axis, the term "tire radial direction" refers to the direction perpendicular to the rotation axis of the tire, and the term "tire width direction" refers to the direction parallel to the rotation axis of the tire. In some drawings, the tire circumferential direction is represented by the symbol "CD", the tire radial direction is represented by the symbol "RD", and the tire width direction is represented by the symbol "WD".

[0028] In this specification, the side of the tire closer to the tire equatorial plane CL along the tire width direction is referred to as the "tire width direction inner side", and the side of the tire farther from the tire equatorial plane CL along the tire width direction is referred to as the "tire width direction outer side".

[0029] In addition, in this specification, the term "extending in the tire circumferential direction" means extending at least with a tire circumferential component. In other words, "extending in the tire circumferential direction" means that it may extend in a direction following the tire circumferential direction (i.e., at an angle of 0° to the tire circumferential direction and not inclined relative to the tire circumferential direction), or it may extend at an angle other than 90° to the tire circumferential direction (i.e., at an angle of inclination greater than 0° and not greater than 90° relative to the tire circumferential direction).

[0030] In addition, in this specification, the term "extending in the tire width direction" means extending at least with a tire width direction component. In other words, the term "extending in the tire width direction" means that it may extend in a direction following the tire width direction (i.e., at an angle of 0° to the tire width direction and not inclined relative to the tire width direction), or it may extend at an angle other than 90° to the tire width direction (i.e., at an angle greater than 0° and other than 90° relative to the tire width).

[0031] Unless otherwise specified, the positional relationship and dimensions of each element shall be measured in the reference state of the tire mounted on the applicable rim, filled with the specified internal pressure and without load. In addition, when the tire is mounted on the applicable rim, filled with the specified internal pressure and loaded with the maximum load, the outer surface of the tire in contact with the road surface is referred to as the "tread contact surface", and the edge of the tread contact surface in the tire width direction is referred to as the "tread end". In addition, in this specification, the term "expanded view of the tread contact surface" refers to a plan view of the tread contact surface in a state where the tread contact surface is expanded on a plane.

[0032] In this specification, "applicable rim" refers to a standard rim of applicable size recorded in the industry standards effective in the area where pneumatic tires are produced and used or to be recorded in the future (measurement rim in the ETRTO standard manual and design rim in the TRA yearbook). The industry standards are such as the JATMA yearbook of JATMA (Japan Automobile Tire Manufacturers Association) in Japan, the standard manual of ETRTO (European Tire and Rim Technical Organization) in Europe, and the yearbook of TRA (Tire and Rim Association) in the United States. In the case of a size not recorded in the aforementioned industrial standards, the "rim" refers to a rim whose width corresponds to the bead width of the pneumatic tire. "Applicable rim" includes, in addition to the current size, the size that will be described in the aforementioned industrial standards. Examples of "sizes to be recorded in the future" include sizes recorded as "FUTURE DEVELOPMENTS" in the 2013 edition of the ETRTO standard manual.

[0033] In this specification, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel under the applicable size and ply grade recorded in the aforementioned JATMA Yearbook or other industry standards. In the case of a size not recorded in the aforementioned industry standards, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for the vehicle on which the tire is installed. In addition, as used herein, "maximum load" refers to the load corresponding to the maximum load capacity in the tire of the applicable size recorded in the aforementioned industry standards, or, for a size not recorded in the aforementioned industry standards, refers to the load corresponding to the maximum load capacity specified for the vehicle on which the tire is installed.

[0034] <Tires>

[0035] First, refer to Figure 1 to Figure 2 , we will explain an example of a tread pattern of a tire that can be obtained using the tire manufacturing method according to any embodiment of the present disclosure.

[0036] Figure 1 and Figure 2 is a development view of a tread contact surface, illustrating an example of a tread pattern of a tire that can be obtained using the tire manufacturing method according to any embodiment of the present disclosure.

[0037] Figure 1 An example of a tread pattern of a tire that can be obtained by the tire manufacturing method according to any embodiment of the present disclosure is illustrated.

[0038] exist Figure 1In the example shown, the tire 10 has a rib pattern on its tread contact surface 15. In other words, the tire 10 in this example has a plurality of (six in the example shown) land portions 14 divided in the tire width direction by a plurality of (five in the example shown) main grooves 13 extending in the tire circumferential direction on the tread contact surface 15, and each land portion 14 is a rib-like land portion extending continuously in the tire circumferential direction.

[0039] like Figure 1 As shown, the tire 10 in this example is provided with sipes 16 on the land portion 14 to improve wear resistance, wet road performance, ice performance, etc. More specifically, Figure 1 In the example shown, each land portion 14 has a plurality of sipes 16 spaced apart from each other in the tire circumferential direction. In this example, as described below, the sipes 16 or more specifically, the plurality of sipes 16 are arranged to avoid the tread rubber 2 (see below). Figure 4 (b) to (d)) of the joint 2a (in some cases it is difficult to see, so in Figure 1 In the example, the tread is provided in a dotted line form (i.e., in a manner not to overlap with the joint portion 2a when the tread contact surface is viewed in the development view). Figure 1 As shown, the sipes 16 or more specifically, the plurality of sipes 16 are all arranged in a straight line in a direction inclined relative to the tire circumferential direction (i.e., in a development view of the tread contact surface, in a direction with an angle greater than 0° relative to the tire circumferential direction) (more specifically, in this example, in a direction also inclined relative to the tire width direction). In addition, in this example, the sipes 16 or more specifically, the plurality of sipes 16 may be arranged so that the depth of the sipes 16 increases as the sipes 16 approach the tire equatorial plane CL from at least one or both tread ends TE (not shown).

[0040] In addition, in this example, Figure 1 As shown, each sipe 16 is arranged in a manner that crosses each land portion 14 (that is, is continuous from one end to the other end of each land portion 14 in the tire width direction). Figure 1 As shown, each sipe 16 is provided so as to extend from one tread end TE to the other tread end TE along a straight line spanning across the main grooves 13 between the land portions 14 (ie, interrupted by the main grooves 13 ).

[0041] However, the tread pattern of the tire that can be obtained by the tire manufacturing method according to any embodiment of the present disclosure is not limited to the above-mentioned rib pattern. Figure 2 The tread pattern may be a block pattern or any other arbitrary tread pattern as long as it has a sipe 16.

[0042] Here, in this specification, the term "sipe" refers to a thin cut in the tread contact surface, and more specifically, refers to a cut in which the sipe width is 1.0 mm or less in an area of ​​50% or more of the sipe depth in the above-mentioned reference state. Here, the "depth of the sipe (sipe depth)" should be measured in a direction perpendicular to the tread contact surface in the above-mentioned reference state, and the "width of the sipe (sipe width)" should be measured in a direction parallel to the tread contact surface in a cross section perpendicular to the extending direction of the sipe on the tread contact surface in the above-mentioned reference state. The sipe width may be constant or may vary in the direction perpendicular to the tread contact surface.

[0043] Note that the tire 10 that can be obtained by the tire manufacturing method according to any embodiment of the present disclosure includes: a tire body portion 11 (see Figure 4 (d)), which is composed of (in other words, used as a material) the following base tire 1 (see Figure 4 ) formed; tread rubber portion 12 (see Figure 1 to Figure 2 as well as Figure 4 (d)), which is composed of (in other words, used as a material) the following tread rubber 2 (see Figure 4 )form.

[0044] In addition to the tread rubber, the tire main body 11 may include general tire components, such as left and right bead portions, a carcass composed of one or more carcass cord layers spanning between these bead portions, a belt portion composed of one or more belt layers arranged on the radial outside of the carcass, and sidewall rubber, etc. These are general tire components other than the tread rubber.

[0045] The tread rubber portion 12 includes at least tread rubber which is a tire component other than the above-mentioned tire body portion.

[0046] Figure 2 Another example of a tread pattern of a tire that can be obtained using the tire manufacturing method according to any embodiment of the present disclosure is illustrated.

[0047] exist Figure 2 In the example shown, the tire 10 has a block pattern on the tread surface 15. In other words, the tire 10 in this example has a plurality of (four in the example shown) land portions 14 divided in the tire width direction by a plurality of (three in the example shown) main grooves 13 extending in the tire circumferential direction on the tread surface 15, and each land portion 14 is a block land portion having a plurality of pattern blocks 14b divided in the tire circumferential direction by transverse grooves 14a extending in the tire width direction.

[0048] like Figure 2As shown, the tire 10 in this example is also provided with sipes 16 on the land portion 14 to improve wear resistance, wet road performance, ice performance, etc. More specifically, Figure 2 In the example shown, each land portion 14 also has a plurality of sipes 16 spaced apart from each other in the tire circumferential direction. In this example, as described below, the sipes 16 or more specifically the plurality of sipes 16 are also arranged to avoid the tread rubber 2 (see below). Figure 4 (b) to (d)) of the joint 2a (in some cases it is difficult to see, so in Figure 2 In the example, the tread is provided in a dotted line form (i.e., in a manner not to overlap with the joint portion 2a when the tread contact surface is viewed in the development view). Figure 2 As shown, the sipes 16 or more specifically, the plurality of sipes 16 are also arranged in a straight line in a direction inclined relative to the tire circumferential direction (i.e., in a development view of the tread contact surface, in a direction at an angle greater than 0° relative to the tire circumferential direction) (more specifically, in this example, at an angle of 90° relative to the tire circumferential direction and 0° relative to the tire width direction, i.e., along the tire width direction). In addition, in this example, the sipes 16 or more specifically, the plurality of sipes 16 may also be arranged so that the depth of the sipes 16 increases as the sipes 16 approach the tire equatorial plane CL from at least one or both tread ends TE (not shown).

[0049] In addition, in this example, Figure 2 As shown, each sipe 16 is arranged such that: in the two land portions 14 on the inner side in the tire width direction near the tire equatorial plane CL, each sipe 16 crosses each of the two land portions 14 (that is, is continuous from one end to the other end of each land portion 14 in the tire width direction); and in the two land portions 14 on the outer side in the tire width direction near the tread end TE, each sipe 16 opens into the main groove 13 but does not reach the tread end TE, and is designed to terminate in the associated land portion 14. In addition, in this example, as shown in FIG. Figure 2 As shown, each sipe 16 is provided so as to extend along a straight line that crosses each main groove 13 between each land portion 14 (that is, is interrupted by each main groove 13 ).

[0050] <Tire Manufacturing Method>

[0051] In the following, reference will be made to Figure 3 and Figure 4 A tire manufacturing method according to one embodiment of the present disclosure is described.

[0052] Figure 3 is a flowchart illustrating a tire manufacturing method according to one embodiment of the present disclosure. Figure 4 2 is a diagram illustrating a tire manufacturing method according to an embodiment of the present disclosure. Figure 4(a) shows a base tire that has been prepared in the base tire preparation step. Figure 4 (b) shows a tire that has been assembled in the tire assembly process. Figure 4 (c) shows the vulcanization process of the molded tire. Figure 4 (d) shows the sipe forming step. Figure 4 (a) to (d) are illustrated as schematic diagrams of cross-sectional views in the tire width direction.

[0053] The tire manufacturing method according to one embodiment of the present disclosure is a method for manufacturing a so-called retreaded tire, and the tire obtained by the tire manufacturing method according to one embodiment of the present disclosure is a retreaded tire.

[0054] Generally speaking, there are two methods for manufacturing retreaded tires: the COLD method (also called the precuring method, etc.) and the HOT method (also called the remolding method, etc.). The tire manufacturing method disclosed in the present invention can be used for both the COLD method and the HOT method. In the COLD method, a vulcanized precured tread is wound around and mounted on the crown portion of a base tire via an unvulcanized buffer rubber, and after the molded tire is formed, the precured tread is vulcanized at a relatively low temperature in a vulcanizing kettle and bonded to the base tire. On the other hand, in the HOT method, an unvulcanized tread rubber is wound around and mounted on the crown portion of a base tire, and the tread rubber is vulcanized at a relatively high temperature through a mold and bonded to the base tire. Figure 4 The shown example is an example of a manufacturing method using the COLD method.

[0055] The tire manufacturing method according to one embodiment of the present disclosure is used to obtain a tire having a tire body portion 11 (see Figure 4 (d)) and the tread rubber portion 12 (see Figure 1 to Figure 2 and Figure 4 (d)) tire.

[0056] like Figure 3 As shown, the tire manufacturing method according to one embodiment of the present disclosure sequentially comprises a base tire preparation process (step S101), a molded tire assembly process (step S102), a molded tire vulcanization process (step S103) and a sipe forming process (step S104).

[0057] (Base tire preparation process)

[0058] First, in the base tire preparation process, a base tire 1 which is a tire main body portion of a used tire and will become the tire main body portion 11 is prepared (step S101 ).

[0059] like Figure 4As shown in (a), the base tire 1 is a portion of a used tire (not shown) from which the worn tread rubber portion is removed, which is originally used as the tire body portion, and is the tire body portion 11 (see FIG. 1 ) of the tire that can be obtained by the manufacturing method of this embodiment. Figure 4 (d)) component.

[0060] The base tire preparation process may include an acceptance process and a tread rubber part removal process, wherein the acceptance process is used to check whether the tire body part other than the tread rubber part of the used tire received from the market, etc. can be reused, and the tread rubber part removal process is used to remove the tread rubber part from the used tire.

[0061] (Molding tire assembly process)

[0062] After the base tire preparation process, in the built tire assembly process, the built tire 4 is assembled by attaching the tread rubber 2 to be the tread rubber portion 12 to the outer peripheral side of the base tire 1 prepared in the base tire preparation process (step S102 ).

[0063] The tread rubber 2 is a tread rubber portion 12 (see FIG. 1 ) of a tire that can be obtained by the tire manufacturing method of the present disclosure. Figure 1 to Figure 2 and Figure 4 The length of the tread rubber 2 may be equivalent to one circumference of the tire.

[0064] As mentioned above, Figure 4 The example shown in FIG. 1 is an example of a general method for manufacturing a retreaded tire using the COLD method. Figure 4 In the example shown, in the tire assembly process, a vulcanized tread rubber 2 (generally referred to as a pre-cured tread) is wrapped and attached to the outer surface of a base tire 1 via an unvulcanized cushion rubber 3 (see FIG. Figure 4 In other words, Figure 4 In the example shown, in the built tire assembly process, a vulcanized tread rubber 2 (generally, referred to as a pre-cured tread) is wound and attached to the outer surface of a base tire 1 via an unvulcanized cushion rubber 3. In other words, Figure 4 In the example shown, the formed tire 4 assembled in the formed tire assembly process is a tire in which the vulcanized tread rubber 2 is wound and attached (or more specifically, adhered) to the outer surface of the base tire 1 via the unvulcanized cushion rubber 3. The length of the unvulcanized cushion rubber 3 may be equivalent to one circumference of the tire.

[0065] In this example, the vulcanized tread rubber 2 used in the molded tire assembly process is in a flat plate shape before being attached to the base tire 1, and a tread pattern (for example, Figure 1 and Figure 2 , excluding the sipes 16). In addition, in this example, in the molded tire assembly process, the unvulcanized cushion rubber 3 may be wound and attached (or more specifically, adhered) to the outer surface of the base tire 1, and then the vulcanized tread rubber 2 may be wound and attached (or more specifically, adhered) to the outer surface of the unvulcanized cushion rubber 3; or the unvulcanized cushion rubber 3 may be pre-attached to the vulcanized tread rubber 2, and the composite may be wound and attached (or more specifically, adhered) to the outer surface of the base tire 1.

[0066] Note that, in this example, in the built tire assembly process, an additional adhesive may be interposed between at least one of the base tire 1 , the unvulcanized cushion rubber 3 , and the vulcanized tread rubber 2 .

[0067] As in the above example, in the molded tire assembly process, when the vulcanized tread rubber 2 is wrapped and attached to the outer surface of the base tire 1 via the unvulcanized buffer rubber 3, the tire can be manufactured on a compact production line because large equipment such as conventional vulcanization molds are not required, especially in the subsequent molded tire vulcanization process, etc.

[0068] However, the tire manufacturing method in this example is not limited to Figure 4 The example shown in the figure can be a method using the HOT method in a general manufacturing method of a retreaded tire. That is, although not shown in the figure, in the molded tire assembly process, the unvulcanized tread rubber 2 can be wound and attached to the outer surface of the base tire 1 without passing through the above-mentioned unvulcanized buffer rubber 3, etc. In other words, the molded tire 4 assembled in the molded tire assembly process can be a tire in which the unvulcanized tread rubber 2 is wound and attached (or more specifically, attached) to the outer surface of the base tire 1 without passing through the unvulcanized buffer rubber 3, etc. In this case, the surface of the unvulcanized tread rubber 2 used in the molded tire assembly process does not need to have a tread pattern formed thereon in advance. In addition, in this case, in the molded tire assembly process, an adhesive can be used between the base tire 1 and the unvulcanized tread rubber 2.

[0069] As in the above example, in the case where the unvulcanized tread rubber 2 is wrapped and attached to the outer surface of the base tire 1 in the molded tire assembly process, since the molded tire 4 is enclosed in a vulcanization mold including a normal tread pattern and vulcanized in the subsequent molded tire vulcanization process, as described below, the joint 2a of the tread rubber 2 formed when the tread rubber 2 is wrapped and attached to the outer surface of the base tire 1 will be less obvious in the circumferential direction of the tire, making it easier to achieve a better appearance of the manufactured tire.

[0070] (Vulcanization process of molded tires)

[0071] After the tire assembly process, during the tire vulcanization process, such as Figure 4 As shown in (c), the formed tire assembled in the formed tire assembly process is vulcanized (step S103) (see Figure 4 (c)). Vulcanization can be carried out using a predetermined vulcanization equipment 6.

[0072] exist Figure 4 In the example shown (i.e., in the case of the aforementioned COLD method, in which, in the molded tire assembly process, the vulcanized tread rubber 2 is wound and attached to the outer surface of the base tire 1 via the unvulcanized cushion rubber 3), since the surface of the vulcanized tread rubber 2 used in the molded tire assembly process already has a tread pattern formed thereon that does not include at least the sipes 16, it is not necessary to vulcanize the molded tire in a normal vulcanization mold including the tread pattern in the molded tire vulcanization process. As the vulcanization equipment 6, for example, a vulcanization mold such as Figure 4 The molded tire 4 is sealed in the vulcanizer CG, and the unvulcanized cushion rubber 3 is vulcanized by heating and pressurizing at a relatively low temperature, so that the vulcanized tread rubber 2 (precured tread) can be vulcanized and bonded to the base tire 1.

[0073] On the other hand, in the case of the aforementioned HOT method (wherein, in the molded tire assembly process, the unvulcanized tread rubber 2 is wound around and attached to the outer surface of the base tire 1), vulcanization in the molded tire vulcanization process is performed using the vulcanization equipment 6 (the vulcanization equipment 6 uses, for example, a mold including a tread pattern (not shown) (the tread pattern is engraved on the mold), and the tread pattern does not include at least the sipes 16 (for example, such as Figure 1 and Figure 2 The tread pattern shown, which does not include the sipes 16 and has the opposite concave and convex) , seals the molded tire 4 inside a vulcanization mold and applies heat and pressure at a relatively high temperature so that the unvulcanized tread rubber 2 can be vulcanized and bonded to the base tire 1.

[0074] However, the vulcanization method used in the vulcanization process of the molded tire and the vulcanization equipment used in the vulcanization process of the molded tire are not limited to the above, as long as the surface 5 (see Figure 4 (d)) has a necessary tread pattern other than the sipes 16, and the vulcanization method and vulcanization equipment can be arbitrary. Note that, on the surface 5 of the tread of the molded tire 4 that has been vulcanized in the molded tire vulcanization process, one or more sipes 16 can be formed as needed in addition to the sipes 16 formed in the sipe forming process described below.

[0075] (Slot Forming Process)

[0076] After the tire vulcanization process, in the sipe forming process, the sipe 16 is formed on the surface 5 of the tread of the tire 4 vulcanized in the tire vulcanization process (step S104) (see Figure 4 (d)). The sipe 16 can be formed by a predetermined sipe forming device 7.

[0077] After the vulcanization treatment in the tire molding vulcanization process, the sipe forming process may form a sipe such as on the surface 5 of the tread of the molded tire 4 (and therefore, on the tread contact surface 15 of the tire 10). Figure 1 and Figure 2 The tread pattern shown is a sipe 16 portion of the tread pattern. Note that Figure 4 For the sake of convenience, the main groove formed on the surface of the tread rubber 2 (the surface 5 of the tread) is included, and the main groove is Figure 1 and Figure 2 The structures (number, etc.) of the main grooves 13 and the like in the tread pattern of the 200 GT GT 500 do not strictly correspond.

[0078] In the knife groove forming process, the knife groove 16 may be formed using knife groove forming equipment 7 such as a cutter (hot knife) or a laser.

[0079] exist Figure 4 In the example shown, use Figure 4 The guillotine cutter GC schematically shown in (d) forms the sipe 16 as the sipe forming equipment 7 in the sipe forming process. Here, the term "guillotine cutter" refers to an equipment that fixes the tire in a manner allowing it to rotate about its rotation axis when the tire is mounted on a rim and filled with a low internal pressure (about 50 kPa) just enough to fit the rim, and then uses a blade (thin blade) that can move in the radial direction of the tire to form sipes while rotating the tire little by little. Figure 4 In (d), the white arrow pointing downward illustrates the appearance of the guillotine cutter GC (or more specifically, the blade of the guillotine cutter GC) moving radially inward toward the surface 5 of the tread of the molded tire 4 after vulcanization to form the sipes.

[0080] The above-mentioned guillotine cutter GC is suitable for forming a plurality of sipes on the surface 5 of the tread having a rib pattern or the like, wherein the land portion 14 (see Figure 1 to Figure 2 ) extends continuously in the tire circumferential direction. In addition, the above laser is suitable for forming a plurality of sipes on the surface 5 of a tread having a block pattern, for example, in which the land portion 14 is interrupted in the tire circumferential direction.

[0081] However, the sipe forming method in the sipe forming process and the sipe forming equipment used in the sipe forming process are not particularly limited to those described above, but may be arbitrary.

[0082] A preferred sipe forming method in the sipe forming step will be described in more detail later.

[0083] Next, the effects of the aforementioned tire manufacturing method according to one embodiment of the present disclosure will be described.

[0084] First, the embodiment includes: a base tire preparation process, in which a base tire 1 is prepared; a molded tire assembly process, in which a molded tire 4 is assembled by attaching a tread rubber 2 to the outer peripheral side of the base tire 1; and a molded tire vulcanization process, in which the molded tire 4 is vulcanized, so that a tire (particularly, a retreaded tire) can be obtained as usual.

[0085] Furthermore, according to the present embodiment, in the molded tire assembly process, the tread rubber 2 is attached to the outer peripheral side of the prepared base tire 1, and in the sipe forming process, the sipes 16 are formed on the surface 5 of the tread of the vulcanized molded tire 4. In other words, according to the present embodiment, the base tire 1 of the tire body part of a used tire is used for the tire body part 11, and the sipes 16 are formed in the molded tire 4 after vulcanization.

[0086] Here, it is known that for a new tire obtained using a conventional manufacturing method (i.e., without using a base tire), after the tire is used for the first time, the tire diameter will increase as the tire has been running for a period of time, and if the new tire has a sipe, there is a risk that the sipe width will increase as the tire diameter increases. In contrast, according to the present embodiment, in the molding tire assembly process, a base tire 1 whose diameter growth has been completed is used, so the tire body 11 of the manufactured tire is the base tire 1 whose diameter growth has been completed. Therefore, compared with a conventional new tire manufactured without using a base tire 1, a tire in which the width of the sipe formed initially is less likely to change can be obtained.

[0087] Furthermore, for example, in a manufacturing method using the above-mentioned COLD method, one possible way is to perform a molded tire assembly process using a vulcanized tread rubber (precured tread) having sipes that are formed in advance by means of a cutter or the like in a state where the vulcanized tread rubber is placed on a flat surface. In this case, during the molded tire assembly process, when the vulcanized tread rubber 2 is wound around and attached to the outer periphery of the base tire 1, there is a risk that the sipe width will also become wider. In contrast, in the present embodiment, the sipes are formed in the sipe forming process after the molded tire 4 is vulcanized, and therefore, compared with the case of assembling a molded tire using a vulcanized tread rubber having preformed sipes in the molded tire assembly process, a tire in which the initially formed sipe width is less likely to vary can be obtained.

[0088] As described above, the tire manufacturing method according to this embodiment makes it possible to obtain a tire in which the groove width is less likely to vary, thereby preventing the effects of the grooves, such as improving wear resistance, from not being fully exerted or cracks from occurring at the bottom of the grooves, which would otherwise be caused by the increase in the groove width.

[0089] Furthermore, according to the present embodiment, the sipes 16 are formed in the molded tire 4 after vulcanization in the sipe forming process using a cutter or a laser, etc., instead of forming the sipes during vulcanization by a vulcanization mold provided with a blade for forming the sipes (for example, in the manufacturing method using the above-mentioned HOT method, one possible way is to form the sipes during vulcanization in the vulcanization mold in the molded tire vulcanization process), and therefore, it is easy to customize the performance of each tire according to customer requirements, etc.

[0090] Next, a preferred sipe forming method and the like in the sipe forming step will be described.

[0091] Note that the arrangement and configuration of the sipes formed in the molded tire 4 in the sipe forming step are substantially the same as the arrangement and configuration of the sipes in the tire 10 obtained by the manufacturing method. Therefore, for ease of explanation, the following description will appropriately refer to the illustration of the tire 10 in question. Figure 1 and Figure 2 .

[0092] First, in the sipe forming process, it is preferred that Figure 1 and Figure 2 As shown, the sipe 16 is formed by avoiding the joint 2a of the tread rubber 2 of the molded tire 4 in the tire circumferential direction (not overlapping with the joint 2a in the unfolded view of the tread contact surface) generated when the tread rubber 2 is attached to the outer peripheral side of the base tire 1 in the molded tire assembly process.

[0093] In this case, a failure due to the sipe 16 is less likely to occur, and thus deterioration in tire durability can be prevented.

[0094] Furthermore, in the sipe forming step, it is preferred that the sipe 16 be formed in a straight line along a direction inclined relative to the tire circumferential direction of the molded tire 4, such as Figure 1 and Figure 2 shown.

[0095] In this case, the formation of the knife groove 16 can be easily performed using, for example, a guillotine cutter GC having a simple linear blade, so that the formation of the knife groove 16 becomes easier.

[0096] In addition, although not shown in the drawings, in the sipe forming process, it is preferred that the sipe 16 is formed in such a manner that the depth of the sipe 16 (sipe depth) becomes deeper as the sipe approaches the center of the molded tire 4 in the tire width direction (i.e., the tire equatorial plane CL).

[0097] In the case of the molded tire 4 that has been subjected to the molded tire vulcanization process, the surface of the tread rubber 2 (the surface 5 of the tread, or the tread contact surface 15) is generally formed in a slightly arcuate shape having a radially outward convex radius R in a cross-sectional view in the tire width direction. Therefore, in the above case, the formation of the sipes 16 can be easily performed using, for example, a guillotine cutter GC having a straight-line blade when viewed from the side, so the formation of the sipes 16 becomes easier.

[0098] Furthermore, in the sipe forming step, it is preferred that Figure 1 and Figure 2 As shown, a plurality of sipes 16 are formed in the molded tire 4 at intervals from each other in the tire circumferential direction.

[0099] In this case, the effects of the sipes 16 such as improvement of wear resistance are more effectively exerted.

[0100] The width of the sipe formed in the sipe forming step (sipe width) is preferably 0.7 mm or less, more preferably 0.5 mm or less, and even more preferably 0.4 mm or less in an area of ​​50% or more of the sipe depth. In addition, the width of the sipe is preferably at least 0.2 mm in an area of ​​at least 50% of the sipe depth. In addition, the sipe width is preferably 0.2 mm to 0.5 mm, and even more preferably 0.2 mm to 0.4 mm in an area of ​​at least 50% of the sipe depth.

[0101] The thinner the sipe width is within the above range of 0.7 mm or less, the more the benefits of the sipe 16 such as improved wear resistance can be exerted, and as described above, making the sipe depth 0.2 mm or more makes it easier to form the sipe using a cutter or the like.

[0102] In order to improve the wear resistance of the tire, it is preferred that in the sipe forming process, Figure 1 and Figure 2 As shown, the sipes 16 are formed in a straight line in a direction inclined relative to the tire circumferential direction of the molded tire 4, and a plurality of sipes 16 are formed spaced apart from each other in the tire circumferential direction of the molded tire 4. In other words, in a development view of the tread contact surface, a plurality of straight sipes 16 extending in the tire width direction are preferably formed at intervals in the tire circumferential direction.

[0103] In this case, the tire circumferential distance between the sipes 16 adjacent in the tire circumferential direction (hereinafter, also simply referred to as "the circumferential distance between (multiple) sipes 16", etc.) is preferably 5 mm to 40 mm. If the interval is 5 mm or more, the rigidity of the land portion 14 will not be excessively reduced (that is, the land portion will not become too soft), and if the interval is 40 mm or less, the rigidity of the land portion 14 is reduced to a moderate degree (that is, the land portion becomes moderately soft), and when the tire rotates, the amount of sliding between the ground and the tire is reduced, so in either case, it is easier to improve the wear resistance. From the same point of view, in the above case, it is more preferable that the circumferential interval of the sipes 16 is 10 mm to 30 mm. In addition, from the same point of view, in the above case, the depth of the sipe 16 is preferably 40% to 100% of the depth of the main groove 13.

[0104] Furthermore, as described above, when a plurality of sipes 16 extending linearly in the tire width direction are formed at intervals in the tire circumferential direction, it is preferred that the sipes 16 have uniform intervals in the tire circumferential direction over the entire circumference, or in other words, the plurality of sipes 16 are formed at equal intervals over the entire circumference of the tire. In this case, the wear resistance and other properties exhibited by the sipes 16 can be made uniform over the entire circumference of the tire.

[0105] A plurality of ribs (e.g., Figure 1 As shown, these ribs result in rib-like land portions 14) and / or blocks (e.g., as shown) in the manufactured tire 10. Figure 2 As shown, these blocks lead to the pattern blocks 14b in the manufactured tire 10) (this is the case of the manufacturing method using the above-mentioned COLD method); or in the process of vulcanizing the molded tire, a plurality of ribs are formed on the surface of the tread rubber 2 (for example, as shown in FIG. Figure 1 As shown, these ribs result in rib-like land portions 14) and / or multiple blocks (e.g., as shown) in the manufactured tire 10. Figure 2 As shown, these blocks result in a pattern block 14b in the manufactured tire 10) (this is the case when the manufacturing method using the above-mentioned HOT method), and in the sipe forming process, a plurality of sipes 16 can be formed on part or all of the plurality of ribs and / or the plurality of blocks in such a manner that the tire circumferential spacing, depth and / or angle relative to the tire circumference are different for each of the plurality of ribs and / or the plurality of blocks.

[0106] In this case, in the sipe forming process, for example, the guillotine cutter GC may be used to form a first type of sipes that are circumferentially spaced from each other around the tire over a portion or the entire circumference of the tire, and then a second type of sipes that are different from the first type and are circumferentially spaced from each other may be formed around the tire over a portion or the entire circumference of the tire. Furthermore, the sipe formation may be repeated, and a third type or more types of sipes that are different from the type of sipes formed up to that point may be formed.

[0107] Furthermore, in the sipe forming step, the sipes 16 may be formed over the entire width of the molded tire 4 (and therefore, the tire 10) in the tire width direction (see, for example, Figure 1 ), or may be formed in only a portion of the width of the tire in the tire width direction (for example, see Figure 2 ).

[0108] Furthermore, in the sipe forming process, the sipes 16 may be formed over the entire width in the tire width direction in each land portion 14, each of which is defined in the tire width direction by the main groove 13 extending in the tire circumferential direction in the molded tire 4 (thus, the tire 10) (see, for example, Figure 1 ), the sipe 16 may be formed only on a portion of the width in the tire width direction in at least a portion of the land portion 14 (for example, see Figure 2 ).

[0109] The above describes the preferred method for forming the knife grooves in the knife groove forming process, etc., however, the method for forming the knife grooves in the knife groove forming process is not particularly limited to the above method, as long as the knife grooves 16 are formed on the surface 5 of the tread of the molded tire 4 that has been vulcanized in the molded tire vulcanization process, the method for forming the knife grooves can be arbitrary.

[0110] According to the tire manufacturing method according to one embodiment of the present disclosure described above, for example, by forming the sipes 16 in the already vulcanized molded tire 4 in a manner such that the sipes have the configuration and structure of the tire 10 in the sipe forming step, it is possible to obtain the tire 10 which uses the tire body portion of a used tire as the tire body portion 11 of the tire and has the tire body portion 12 of the tire 10 as shown in FIG. Figure 1 and Figure 2 The tread pattern is illustrated.

[0111] Furthermore, according to the tire manufacturing method according to one embodiment of the present disclosure, for example, by using a general guillotine cutter or the like whose blade thickness is constant in the depth direction of the sipes 16 to be formed in the sipe forming process, a tire 10 can be obtained, which includes a tire body portion 11 and a tread rubber portion 12, wherein the tire body portion 11 is composed of a base tire 1 of a tire body portion of a used tire; a plurality of sipes 16 are formed on the surface of the tread rubber portion 12; and each of the aforementioned plurality of sipes 16 has a substantially constant width in the depth direction. The width of the sipes in the tire 10 does not easily vary.

[0112] The above description is an example of an exemplary embodiment of the present disclosure, and various changes may be made without departing from the scope of the claims.

[0113] For example, in the present disclosure, in the case where the vulcanized tread rubber 2 is wound and attached to the outer periphery of the base tire 1 via the unvulcanized cushion rubber 3 in the molded tire assembly process (i.e., in the case of the above-mentioned COLD method), there may be an additional encapsulation process of wrapping the molded tire 4 in a rubber bag between the molded tire assembly process and the molded tire vulcanization process. In addition, for example, in the present disclosure, after the molded tire vulcanization process and / or the sipe forming process, there may be an inspection process of inspecting whether there is any abnormality in the vulcanized molded tire 4 and / or the tire 10 after the sipe formation, etc.

[0114] Industrial Applicability

[0115] The tire manufacturing method disclosed herein can be appropriately used as a manufacturing method for any type of pneumatic tire, such as TB tires (tires for trucks and buses), LT tires (tires for vans and small trucks, tires for small trucks and buses), OR tires (tires for construction and mining vehicles), etc., and can be particularly well used as a manufacturing method for TB tires or LT tires.

[0116] Reference numerals list

[0117] 1 base tire

[0118] 2. Tread rubber

[0119] 2a Joint

[0120] 3. Buffer rubber

[0121] 4Molding tire

[0122] 5. Tread surface

[0123] 6Vulcanization equipment

[0124] 7. Slot forming equipment

[0125] 10 Tires

[0126] 11 Tire body

[0127] 12. Tread rubber part

[0128] 13 Main Slot

[0129] 14 Land Department

[0130] 14a Horizontal groove

[0131] 14b Tread Block

[0132] 15 Tread contact patch

[0133] 16 Slots

[0134] CC Vulcanizing Reactor

[0135] CD Tire Circumferential Direction

[0136] CL Tire equatorial plane

[0137] GC Guillotine Cutter

[0138] RD radial tire

[0139] WD tire width direction

Claims

1. A tire manufacturing method for obtaining a tire including a tire body portion and a tread rubber portion, the tire manufacturing method comprising: a base tire preparation step, wherein a base tire is prepared, the base tire being a tire body portion of a used tire and serving as the tire body portion; a molded tire assembling step of assembling the molded tire by attaching a tread rubber to be the tread rubber portion to the outer peripheral side of the prepared base tire; a molded tire vulcanization step, wherein the assembled molded tire is vulcanized; and The sipe forming step includes forming sipes on the surface of the tread of the vulcanized molded tire.

2. The tire manufacturing method according to claim 1, wherein: In the molded tire assembly process, the vulcanized tread rubber is wound and attached to the outer circumference of the base tire via unvulcanized cushion rubber.

3. The tire manufacturing method according to claim 1, wherein: In the built tire assembly process, the unvulcanized tread rubber is wound and attached to the outer circumference of the base tire.

4. The tire manufacturing method according to any one of claims 1 to 3, wherein: In the sipe forming step, the sipe is formed avoiding a joining portion of the tread rubber of the molded tire in a tire circumferential direction.

5. The tire manufacturing method according to any one of claims 1 to 3, wherein: In the sipe forming step, the sipe is formed in a straight line along a direction inclined with respect to a tire circumferential direction of the molded tire.

6. The tire manufacturing method according to any one of claims 1 to 3, wherein: In the sipe forming step, the sipe is formed so that the depth of the sipe increases as the sipe approaches the center in the tire width direction of the molded tire.

7. The tire manufacturing method according to any one of claims 1 to 3, wherein: In the sipe forming step, a plurality of the sipes are formed in the molded tire at intervals from each other in a tire circumferential direction.

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