Tire mold

Abstract

Provided is a tire mold that, while ensuring the strength required by a side mold, is capable of discharging, via mating surfaces of a tread mold and the side mold, gas that has accumulated in the interior of the tire mold. A tire mold (1) is provided with a mold (2) and a mold (3). A mating-surface-side inner surface (F31) of the mold (3) is inclined inward, and a through-hole (5) that opens in the mating-surface-side inner surface (F31) and a mating surface (Fm3) is formed in the mold (3). A communication groove (6) that leads to the through-hole (5) is formed in the mating surface (Fm3) of the mold (3). The communication groove (6) forms a communication path (R6) that leads to the through-hole (5) when the molds (2, 3) are mated. Furthermore, the mold (3) has, formed in the mating surface (Fm3), a recessed section (7) that leads to the communication groove (5). When the molds (2, 3) are mated, the recessed section (7) forms a filling space (S7) that communicates with the communication path (R6) and has a larger volume than the total volume of the through-hole (5) and the communication path (R6).

Description

tire mold

[0001] This application claims priority to Japanese Patent Application No. 2023-203032, filed on November 30, 2023, the entire contents of which are incorporated herein by reference.

[0002] A known conventional tire mold is one in which the inner surface of the mating surface between the tread mold and the side mold forms an inclined surface, and the side mold has air vents formed therein that connect the inner surface of the mating surface of the side mold to the mating surface with the tread mold in order to discharge air that has accumulated on the inner surface of the mating surface of the tire mold in the direction normal to the inner surface of the mold (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2017-109366

[0004] However, since the vent holes are through-holes that open at an angle to the mating surface of the side mold, simply providing the vent holes in the side molds means that the mating surface of the tread mold will block the vent holes when the tire mold is clamped.

[0005] Therefore, the conventional tire mold is provided with a space called a communication opening that communicates with the vent hole at the mating surface between the tread mold and the side mold, and with the conventional tire mold, the space can communicate the vent hole with the outside of the tire mold.

[0006] However, when a recess that defines part of the space is formed in the mating surface of the side mold so as to directly connect the vent hole to the space, the position of the recess on the mating surface F of the side mold needs to be set so as to maintain the strength required for the side mold, and therefore a configuration in which the vent hole is directly connected to the space is not effective.

[0007] An object of the present invention is to provide a tire mold that can discharge gas accumulated inside the tire mold through the mating surface between the tread mold and the side mold while ensuring the strength required of the side mold.

[0008] (1) A tire mold according to the present invention is a tire mold comprising a tread mold and a side mold, wherein an inner surface of the side mold, which is adjacent to a mating surface of the tread mold and which is continuous with the mating surface of the tread mold, is inclined inwardly toward the mating surface of the tread mold, and a through hole is formed in the side mold, one end of which opens to the inner surface of the mating surface of the side mold and the other end of which opens to the mating surface of the tread mold, and the side mold has a through hole formed in the mating surface of the tread mold. a communicating groove having one end communicating with the other end of the communicating groove and extending from that end toward the outside in the tire axial direction of the side mold, the communicating groove forming a communicating passage leading to the through hole when the tread mold and the side mold are mated, and further, the side mold has a recess formed in its mating surface with the tread mold that communicates with the other end of the communicating groove, the recess forming a filling space that communicates with the communicating passage and has a volume greater than the total volume of the through hole and the communicating passage when the tread mold and the side mold are mated. The tire mold of the present invention makes it possible to discharge gas accumulated inside the tire mold through the mating surface of the tread mold and side mold while ensuring the strength required of the side mold.

[0009] (2) In the tire mold of (1) above, it is preferable that the filling space is a closed space that is closed off from the outside of the tire mold when the tread mold and the side mold are combined together. In this case, gas inside the tire mold does not leak out to the outside of the tire mold, resulting in a tire mold with excellent heat retention and increased strength.

[0010] (3) In the tire mold of (1) or (2) above, it is preferable that a spring vent is disposed inside the through hole. In this case, a tire with reduced appearance defects such as spew can be obtained.

[0011] (4) In any one of the tire molds (1) to (3) above, the recess is preferably positioned at a position 20 mm or more outward in the tire axial direction from the inner edge of the mating surface with the tread mold, which makes it possible to easily obtain the strength required for the side molds.

[0012] (5) In any one of the tire molds (1) to (4) above, the through holes are preferably positioned 8 mm or less along the inner surface of the side mold mating surface from the inner edge of the mating surface with the tread mold. In this case, the strength required for the side molds can be easily obtained.

[0013] According to the present invention, it is possible to provide a tire mold that can discharge gas accumulated inside the tire mold through the mating surface between the tread mold and the side mold while ensuring the strength required of the side mold.

[0014] FIG. 1 is a cross-sectional view showing a schematic half section of a tire mold according to one embodiment of the present invention, with the tire mold shown in a state where the tread mold has been released from the side mold. FIG. 2 is another cross-sectional view of the tire mold of FIG. 1, with the tire mold shown in a clamped state. FIG. 3 is a cross-sectional view showing an enlarged view of a portion of region X of the tire mold of FIG. 2. FIG. 4 is an outline view showing a schematic cross-sectional shape of a flow path of a communication passage in the tire mold of FIG. 1. FIG. 5 is a perspective view showing one of two side molds in the tire mold of FIG. 1 assembled over the entire circumferential direction of the tire. FIG. 6 is a cross-sectional view showing a schematic example of a spring vent applicable to the tire mold of FIG. 1. FIG. 7 is a cross-sectional view showing a schematic view of a main portion of a tire mold according to another embodiment of the present invention, corresponding to region X of FIG. 2.

[0015] A tire mold according to an exemplary embodiment of the present invention will now be described with reference to the drawings.

[0016] Fig. 1 shows a schematic half cross section of a tire mold 1 according to one embodiment of the present invention, as viewed from a cross section in the tire axial direction including a tire center axis O1 of a tire (product tire) molded by the tire mold 1 (hereinafter also referred to as a "cross section in the tire axial direction").

[0017] Here, the symbol O1 denotes the tire central axis. The tire central axis O1 (hereinafter also simply referred to as the "center axis O1") corresponds to the central axis (rotational center axis) of the product tire. Furthermore, the symbol O2 denotes the tire radial axis. The tire radial axis O2 (hereinafter also simply referred to as the "tire radial axis O2") is an axis perpendicular to the tire central axis O1. Furthermore, the symbol PC denotes the intersection of the tire central axis O1 and the tire radial axis O2.

[0018] In the following description, the tire axial direction refers to the direction in which the tire center axis O1 extends or a direction parallel to that direction. In the tire axial direction, the side closer to the intersection point PC is referred to as the tire axial inner side, and the side farther from the intersection point PC is referred to as the tire axial outer side. In addition, the tire radial direction refers to the direction in which the tire radial axis O2 extends or a direction parallel to that direction. In the tire radial direction, the side closer to the intersection point PC is referred to as the tire radial inner side, and the side farther from the intersection point PC is referred to as the tire radial outer side. In addition, the tire circumferential direction refers to the circumferential direction around the tire center axis O1.

[0019] 1, a tire mold 1 includes a tread mold 2 and side molds 3. In this embodiment, the tire mold 1 includes a pair of side molds 3 on the outer sides in the tire axial direction.

[0020] In this embodiment, the inner surface F2 of the tread mold 2 forms the outer shape of the tread portion of the tire and also forms part of the outer shape of the shoulder portion of the tire. Fig. 1 exemplarily shows, of the inner surfaces F2 of the tread mold 2, a tread-side inner surface F21 that forms the tread surface of the product tire and a shoulder-side inner surface F22 that forms part of the outer surface of the shoulder portion of the product tire.

[0021] In this embodiment, the inner surface F3 of the side mold 3 forms the remainder of the outer surface of the shoulder portion of the product tire and also forms the outer surface of the sidewall portion of the product tire. Fig. 1 exemplarily shows, of the inner surface F3 of the side mold 3, a shoulder-side inner surface F31 that forms the remainder of the outer surface of the shoulder portion of the product tire, and sidewall-side inner surfaces F32, F33 that form the outer surfaces of the sidewall portion of the product tire.

[0022] Additionally, in this embodiment, the tire mold 1 is provided with a pair of bead molds 4. In this embodiment, the tire mold 1 is provided with a pair of bead molds 4 on the outer side in the tire axial direction. In Fig. 1, the bead molds 4 are shown mated with the side molds 3 on the inner side in the tire axial direction of the side molds 3. Fig. 1 exemplarily shows the inner surface F4 of the bead mold 4, which forms the outer surface of the bead portion of a product tire.

[0023] Furthermore, the tread mold 2 has a side mating surface Fm2. The side mating surface Fm2 is a mating surface with the side mold 3. In contrast, the side mold 3 has a tread mating surface Fm3. The tread mating surface Fm3 is a mating surface with the tread mold 2. As shown in FIG. 2 , the tire mold 1 according to this embodiment is clamped with the side mating surface Fm2 of the tread mold 2 and the tread mating surface Fm3 of the side mold 3 mated to each other.

[0024] Region X in FIG. 2 is shown enlarged in FIG.

[0025] In the tire mold 1, of the inner surfaces F3 of the side mold 3, a mating surface side inner surface (F31) continuing to the tread side mating surface Fm3 is inclined inward toward the tread side mating surface Fm3.

[0026] In this embodiment, the mating surface-side inner surface of the side mold 3 is a shoulder-side inner surface F31 of the side mold 3. As shown in Fig. 3 , the shoulder-side inner surface F31 is inclined inward in the tire axial direction as it extends outward in the tire radial direction in a cross section in the tire axial direction. Also, in this embodiment, the tread-side mating surface Fm3 of the side mold 3 extends in the tire axial direction in a cross section in the tire axial direction as shown in Fig. 3 .

[0027] A through hole 5 is formed in the side mold 3. One end 5a of the through hole 5 opens to the inner surface of the mating surface side of the side mold 3, i.e., the shoulder-side inner surface F31, while the other end 5b of the through hole 5 opens to the mating surface with the tread mold 2, i.e., the tread-side mating surface Fm3.

[0028] In this embodiment, the through hole 5 extends in a normal direction to the shoulder-side inner surface F31 of the side mold 3. That is, in this embodiment, the through hole 5 extends perpendicular to the shoulder-side inner surface F31. In this embodiment, the through hole 5 extends linearly on the plane of the tire axial cross section, as shown in FIG. 3 . In this case, the through hole 5 leads to the filling space S7 (described later) via the shortest distance. However, the through hole 5 may extend obliquely in the circumferential direction (the direction perpendicular to the drawing in FIG. 3 ) so as to intersect with the tire axial cross section. The through hole 5 may also meander in the circumferential direction. That is, the path of the through hole 5 is not particularly limited. Furthermore, in this embodiment, the shape of the cross section perpendicular to the extension direction of the through hole 5, i.e., the flow path cross section of the through hole 5, is round. However, the flow path cross section of the through hole 5 may be elliptical, polygonal, or the like.

[0029] Furthermore, the side mold 3 has a communication groove 6 formed in its mating surface with the tread mold 2, i.e., the tread-side mating surface Fm3, the communication groove 6 having one end 6a that communicates with the other end 5b of the through hole 5 and extending from the one end 6a toward the outside in the tire axial direction of the side mold 3. As shown in Figure 3, the communication groove 6 forms a communication passage R6 that communicates with the through hole 5 when the tread mold 2 and the side mold 3 are mated.

[0030] In this embodiment, the communicating groove 6 is a groove formed in the tread-side mating surface Fm3, as shown in FIG. 1 . The communicating groove 6 is open to the tread-side mating surface Fm3 of the side mold 3, as shown in FIG. 1 . In this embodiment, the communicating groove 6 extends linearly in the tire axial direction in the tire axial cross section, as shown in FIG. 1 . In this embodiment, the communicating groove 6 extends linearly on the plane of the tire axial cross section, as shown in FIG. 1 . In this case, the communicating groove 6 leads to a filling space S7, which will be described later, via the shortest distance. However, the communicating groove 6 may extend obliquely in the circumferential direction (a direction perpendicular to the drawing in FIG. 3 ) so as to intersect with the tire axial cross section. The communicating groove 6 may also meander in the circumferential direction. That is, the path of the communicating groove 6 is also not particularly limited.

[0031] Furthermore, FIG. 4 schematically illustrates the cross-sectional shape of the communicating channel R6. In FIG. 4, the straight line portion of the communicating channel R6 (communicating groove 6) at the top of the drawing corresponds to the tread-side mating surface Fm3 of the side mold 3. FIG. 4 also illustrates the height of the communicating channel R6, i.e., the depth d of the communicating groove 6. FIG. 4 also illustrates the width of the communicating channel R6, i.e., the width w of the communicating groove 6. In this embodiment, the communicating groove 6 is a U-shaped groove as shown in FIG. 4. A U-shaped groove is a groove whose cross-sectional shape (cross-sectional shape of the communicating channel) is U-shaped. In this embodiment, as shown in FIG. 4, the bottom of the communicating groove 6 is formed by a curved surface with a curvature radius r in a cross-sectional view of the communicating channel. The depth d [mm] of the communicating groove 6 can be, for example, 0.5≦d≦1.2. The curvature radius r [mm] can be 0.5≦r≦1.0. However, the communicating passage R6 may be a groove other than a U-shaped groove. For example, the communicating groove 6 may be a V-shaped groove. A V-shaped groove is a groove whose cross-sectional shape (flow path cross-sectional shape) is V-shaped. When the communicating groove 6 is a groove other than a U-shaped groove, the width w [mm] of the communicating groove 6 may be, for example, 2.5≦w≦3.5.

[0032] 3 , in this embodiment, the area of ​​a cross section perpendicular to the extension direction of the communicating passage R6, i.e., the flow path cross-sectional area of ​​the communicating passage R6, is different from the flow path cross-sectional area of ​​the through hole 5. For example, the communicating passage R6 can be made into an enlarged flow path by making the flow path cross-sectional area of ​​the communicating passage R6 larger than the flow path cross-sectional area of ​​the through hole 5. Furthermore, for example, the communicating passage R6 can be made into a throttled flow path by making the flow path cross-sectional area of ​​the communicating passage R6 smaller than the flow path cross-sectional area of ​​the through hole 5.

[0033] In this embodiment, the flow path cross-sectional shape of the through hole 5 is constant throughout the extension direction of the through hole 5. However, the flow path cross-sectional shape (flow path cross-sectional area) of the through hole 5 can be formed so as to expand outward in the tire axial direction, i.e., toward the communication passage R6. Also, the through hole 5 can be formed so that the flow path cross-sectional shape contracts outward in the tire axial direction. That is, in this embodiment, the flow path cross-sectional shape of the through hole 5 can be expanded or contracted outward in the tire axial direction.

[0034] In this embodiment, the cross-sectional shape of the communication passage R6 is also the same throughout the extension direction of the communication passage R6. However, the cross-sectional shape (cross-sectional area) of the communication passage R6 can be formed to expand toward the filling space S7 described below, i.e., toward the outside in the tire axial direction. The cross-sectional shape of the communication passage R6 can also be formed to contract toward the outside in the tire axial direction. That is, in this embodiment, the cross-sectional shape of the communication passage R6 can be expanded or contracted toward the outside in the tire axial direction.

[0035] 3 , for example, the side mold 3 has a recess 7 formed in its mating surface with the tread mold 2, i.e., the tread-side mating surface Fm3, that communicates with the other end 6b of the communicating groove 6. When the tread mold 2 and the side mold 3 are mated, the recess 7 forms a filling space S7 that communicates with the communicating passage R6 and has a volume that is greater than or equal to the total volume of the through holes 5 and the communicating passages R6. Here, in this embodiment, the phrase "the volume of the filling space S7 is greater than the total volume of the through holes 5 and the communicating passages R6" means that, when a through hole 5 and a communicating groove 6 communicating with the through hole 5 are considered as one set, the volume of one filling space S7 that communicates with the one set is greater than the total volume of the through holes 5 and the communicating passages R6 of the one set.

[0036] In this embodiment, filling space S7 is a space filled with gas that has accumulated inside (cavity space) of tire mold 1. In this embodiment, of the gas that has accumulated between unvulcanized rubber for tire molding and the inner surface (cavity surface) of tire mold 1, the gas that has accumulated between the unvulcanized rubber and the inner surface (F22, F31) of tire mold 1 that forms the shoulder portion of the product tire is evacuated from one end 5 a of through hole 5 via through hole 5 and communicating passage R6 and filled into filling space S7.

[0037] In this embodiment, the cross-sectional area of ​​the filling space S7 perpendicular to the extension direction, i.e., the flow path cross-sectional area of ​​the filling space S7, is different from the flow path cross-sectional area of ​​the communication passage R6. The flow path cross-sectional area of ​​the filling space S7 is made larger than the flow path cross-sectional area of ​​the communication passage R6, thereby forming an expanded space.

[0038] In this embodiment, the flow path cross-sectional shape (flow path cross-sectional area) of the filling space S7 is constant throughout the extension direction of the filling space S7. However, the flow path cross-sectional shape of the filling space S7 can be formed so as to expand outward in the tire axial direction. Also, the flow path cross-sectional shape of the filling space S7 can be formed so as to contract outward in the tire axial direction. That is, in this embodiment, the flow path cross-sectional shape of the filling space S7 can be expanded or contracted outward in the tire axial direction.

[0039] In this embodiment, the filling space S7 is a closed space that is closed off from the outside of the tire mold 1 when the tread mold 2 and the side mold 3 are combined.

[0040] In the present embodiment, one end 7a of the recess 7 communicates with the other end 6b of the communicating groove 6, and the other end 7b of the recess 7 is closed by a step 3a that protrudes outward in the tire radial direction. In the present embodiment, the tire radially outer step surface (tread-side step surface) of the step 3a forms the same plane as the tread-side mating surface Fm3 of the side mold 3. As a result, in the present embodiment, the tire axially outer side of the filling space S7 is closed by the step 3a of the side mold 3, as shown in FIG. 3 . Specifically, in the present embodiment, when the tread mold 2 and the side mold 3 are mated, the tire axially outer side of the filling space S7 is closed by the side-side mating surface Fm2 of the tread mold 2 and the tread-side step surface of the step 3a of the side mold 3, which serves as the tread-side mating surface Fm3 of the side mold 3. As a result, in the present embodiment, the filling space S7 is a closed space that is closed off from the outside of the tire mold 1. Therefore, in this embodiment, the gas discharged into the filling space S7 is not discharged to the outside of the tire mold 1. As a result, the heated gas is stored in the filling space S7.

[0041] FIG. 5 schematically shows one of the two side molds 3 assembled over the entire circumferential direction of the tire. Note that FIG. 5 only shows one through hole 5 connected to the communicating groove 6, with the other through holes 5 omitted. As shown in FIG. 5 , in this embodiment, the recess 7 is an annular recess extending circumferentially around the tire axial axis O1. This allows the communicating groove 6 formed in the tread-side mating surface Fm3 of the side mold 3 to communicate with the recess 7 regardless of its circumferential position. In this case, flexibility is provided in the positioning of the communicating groove 6 when arranging the communicating groove 6 around the tire axial axis O1. Furthermore, the annular recess 7 facilitates connection with the communicating groove 6 (installation of the communicating groove 6). In particular, as shown in FIG. 5 , when a through hole 5 and a communicating groove 6 connected to the through hole 5 are considered as one set and there are multiple such sets, the flexibility in arranging the communicating groove 6 is improved, and the communicating groove 6 can also be easily installed. However, the recesses 7 do not have to be provided annularly, but can be provided intermittently in the circumferential direction.

[0042] FIG. 6 shows a schematic diagram of an example of a spring vent that can be applied to the tire mold 1.

[0043] In the tire mold 1, a vent piece serving as a check valve is preferably disposed inside the through hole 5. In the present embodiment, a spring vent 10 serving as a vent piece is disposed inside the through hole 5. An example of the spring vent 10 is a spring vent manufactured by Glebus Alloys.

[0044] In this embodiment, the spring vent 10 includes a shaft valve 11, a housing 12, and a spring 13. In this embodiment, the shaft valve 11 is housed inside the housing 12. The lower end of the shaft valve 11 functions as a valve body 11a for opening and closing an opening A1 formed at the lower end of the housing 12. The spring 13 is housed inside the housing 12 together with the shaft valve 11. The spring 13 biases the shaft valve 11 toward the interior of the tire mold 1 (the upper side of FIG. 6 ). As a result, in this embodiment, the shaft valve 11 is maintained in a state in which the valve body 11a of the shaft valve 11 closes the opening A1 of the housing 12, as shown in FIG. 6 . That is, in this embodiment, the spring vent 10 closes the interior of the through-hole 5 in its initial state. On the other hand, when the pressure of the gas accumulated inside the tire mold 1 increases, the gas pressure causes the shaft valve 11 to move toward the side mating surface Fm2 (lower side in FIG. 6 ) of the tread mold 2 against the biasing force of the spring 13. This enables the valve body 11a of the shaft valve 11 to open the opening A1 of the housing 12. Therefore, when the pressure of the gas accumulated inside the tire mold 1 increases above a certain level, the spring vent 10 can discharge the gas from the through hole 5 through the communicating passage R6 to the filling space S7.

[0045] However, the through hole 5 is a through hole that opens obliquely with respect to the tread-side mating surface Fm3 of the side mold 3. Therefore, if the through hole 5 is simply provided in the side mold 3, the side-side mating surface Fm2 of the tread mold 2 may block the through hole 5 when the tire mold 1 is clamped.

[0046] Therefore, if a filling space S7 communicating with the through hole 5 is provided on the mating surface between the tread mold 2 and the side mold 3, the through hole 5 can be made to communicate with the filling space S7 without blocking the through hole 5. As a result, gas accumulated inside the tire mold 1 is discharged through the through hole 5 into the filling space S7.

[0047] However, when the filling space S7 is directly connected to the through hole 5, a recess 7 that defines a part of the filling space S7 is formed in the tread-side mating surface Fm3 of the side mold 3. In this case, the side mold 3, particularly the shoulder-side inner surface F31 of the side mold 3, cannot maintain the strength required of the side mold 3. For this reason, the configuration in which the through hole 5 is directly connected to the filling space S7 is not effective.

[0048] In contrast, as shown in Fig. 3 , the tire mold 1 according to this embodiment has a through hole 5 in the side mold 3 that communicates from the shoulder-side inner surface F31 to the tread-side mating surface Fm3. This allows the portion of the interior of the tire mold 1 that corresponds to the inclined surface of the tire shoulder, where gas is likely to accumulate, to communicate with the mating surfaces (Fm2, Fm3) between the tread mold 2 and the side mold 3. The tire mold 1 also has a communication groove 6 in the tread-side mating surface Fm3 of the side mold 3 that communicates with the through hole 5. The communication groove 6 forms a communication passage R6 that communicates with the through hole 5 when the tread mold 2 and the side mold 3 are mated. This allows the through hole 5 to communicate outward in the tire axial direction along the mating surfaces (Fm2, Fm3) between the tread mold 2 and the side mold 3. Furthermore, the tire mold 1 is provided with a recess 7 in the tread-side mating surface Fm3 of the side mold 3, which recess 7 communicates with the communicating groove 6 and has a volume larger than the total volume of the through hole 5 and the communicating passage R6. The recess 7 forms a filling space S7 in the mating surface (Fm2, Fm3) between the tread mold 2 and the side mold 3, outward of the communicating passage R6 in the tire axial direction, which communicates with the communicating passage R6 and has a volume larger than the total volume of the through hole 5 and the communicating passage R6. As a result, the recess 7, which forms the filling space S7 with a volume larger than the through hole 5, communicates with the through hole 5 via the communicating groove 6 without being directly connected to the through hole 5.

[0049] That is, with the tire mold 1, the filling space S7, which has a larger volume than the through hole 5, is not directly connected to the through hole 5 but is formed at a position on the tread-side mating surface Fm3 of the side mold 3, away from the through hole 5. In this case, the side mold 3, and particularly the shoulder-side inner surface F31 of the side mold 3, is spaced further away from the filling space S7 than in a case where the filling space S7 is directly connected to the through hole 5, thereby increasing the strength of the side mold 3. Therefore, with the tire mold 1, it is possible to discharge gas that has accumulated inside the tire mold 1 through the mating surfaces (Fm2, Fm3) between the tread mold 2 and the side mold 3 while ensuring the strength required of the side mold 3.

[0050] 3 , in tire mold 1, filling space S7 is a closed space that is closed off from the outside of tire mold 1 when tread mold 2 and side mold 3 are combined. In this case, in the clamped state, there is no gas passage that connects through holes 5 with the outside of tire mold 1. Therefore, in this case, gas inside tire mold 1 does not flow out to the outside of tire mold 1, resulting in a tire mold with excellent heat retention and an increased strength because no extra flow path leading to the outside is required.

[0051] The tire mold 1 according to this embodiment has a spring vent 10 disposed inside the through hole 5. The spring vent 10 functions as a check valve for discharging only gas accumulated inside the tire mold 1. In this case, a tire with reduced appearance defects such as spew can be obtained. Furthermore, from the perspective of the aesthetic appearance of the product tire, it is preferable that the spring vent 10 not protrude obliquely from the through hole 5 into the tire mold 1. In contrast, with the tire mold 1, the through hole 5 can extend in the normal direction to the shoulder-side inner surface F31 of the side mold 3. That is, in this embodiment, the through hole 5 can extend perpendicular to the shoulder-side inner surface F31. Therefore, with this embodiment, the spring vent 10 can also extend perpendicular to the shoulder-side inner surface F31. Therefore, with this embodiment, the spring vent 10 does not protrude obliquely from the through hole 5 into the tire mold 1, and the product tire has an excellent aesthetic appearance.

[0052] Furthermore, in the tire mold 1 according to this embodiment, it is preferable that the recess 7 formed in the tread side mating surface Fm3 of the side mold 3 is positioned at the inner end of the mating surface with the tread mold 2, i.e., at a position 20 mm or more outward from the inner end of the tread side mating surface Fm3 of the side mold 3.

[0053] 3 , in this embodiment, the recess 7 is disposed at a position spaced a distance L1 outward in the tire axial direction from the tire axially inner end 3e of the tread-side mating surface Fm3 of the side mold 3. In this embodiment, the dimension L1 is the distance in the tire axial direction between the tire axially inner end 3e of the tread-side mating surface Fm3 and one end 7a of the recess 7 (the other end 6b of the communicating groove 6). In this embodiment, the dimension L1 is 20 mm or greater.

[0054] In the present embodiment, when the recess 7 is positioned at a position 20 mm or more away from the inner end (3 e) of the tread side mating surface Fm3 of the side mold 3, for example, the strength required for the side mold 3 can be easily obtained while arranging the spring vent 10 inside the through hole 5.

[0055] Furthermore, in the tire mold 1 according to this embodiment, the through holes 5 are preferably positioned at a position 8 mm or less from the inner end of the mating surface with the tread mold 2, i.e., the inner end of the tread-side mating surface Fm3 of the side mold 3, along the mating surface-side inner surface of the side mold 3, i.e., the shoulder-side inner surface F31.

[0056] As shown in FIG. 3 , in this embodiment, the through hole 5 is disposed at a position spaced a distance L2 from the tire axially inner end 3e of the tread-side mating surface Fm3 of the side mold 3 toward the tire radially inward direction along the shoulder-side inner surface F31 of the side mold 3. In this embodiment, the dimension L2 is the distance (in this example, a linear distance) measured along the shoulder-side inner surface F31 between the tire axially inner end 3e of the tread-side mating surface Fm3 and one end 5a of the through hole 5. Specifically, as shown in FIG. 3 , the dimension L2 is the distance between the tire axially inner end 3e of the tread-side mating surface Fm3 and the edge of one end 5a of the through hole 5 that is closest to the tread-side mating surface Fm3. In this embodiment, the dimension L2 is a maximum of 8 mm. More preferably, the dimension L2 is 5 to 6 m.

[0057] In the present embodiment, when the through hole 5 is positioned 8 mm or less from the inner end of the tread-side mating surface Fm3 of the side mold 3 along the mating surface-side inner surface of the side mold 3, i.e., from the inner end 3 e in the tire axial direction of the tread-side mating surface Fm3 along the shoulder-side inner surface F31, it is possible to easily obtain the strength required of the side mold 3 while, for example, arranging a spring vent 10 inside the through hole 5.

[0058] Figure 7 is a cross-sectional view showing a main part of a tire mold according to another embodiment of the present invention, corresponding to the area X in Figure 2. Parts that are substantially the same as those in the above-described embodiment are given the same reference numerals, and their description will be omitted.

[0059] 7 , in this embodiment, the step 3a of the side mold 3 protrudes toward the tread mold 2, i.e., outward in the tire radial direction, so as to form a step in the tread-side mating surface Fm3 of the side mold 3. In contrast, the tread mold 2 has a step 2a that accommodates the step 3a of the side mold 3. That is, the step 2a of the tread mold 2 is recessed outward in the tire radial direction. As a result, in this embodiment, the tire axially outer side of the filling space S7 is more reliably closed by a contact portion between the tire radially inner mating surface Fm21 of the step 2a of the tread mold 2 and the tire radially outer mating surface Fm31 of the step 3a of the side mold 3, and a contact portion between the tire axially inner mating surface Fm22 of the step 2a of the tread mold 2 and the tire axially outer mating surface Fm32 of the step 3a of the side mold 3. Therefore, in this embodiment, the gas discharged into the filling space S7 is not reliably discharged to the outside of the tire mold 1.

[0060] The above-described exemplary embodiments of the present invention are merely illustrative, and the present invention is not limited to the above-described embodiments, but may be modified in various ways within the scope of the appended claims.

[0061] For example, the side mold 3 according to each of the above embodiments may have at least one through hole 5, and therefore at least one communicating groove 6 (communicating passage R6). Specifically, the communicating grooves 6 may be arranged at intervals in the circumferential direction around the tire center axis O1, for example, 24 communicating grooves 6. Also, the communicating grooves 6 may be arranged at intervals in the circumferential direction, for example, 8 to 16 communicating grooves 6. The communicating grooves 6 may be arranged at any intervals in the circumferential direction. Also, the communicating grooves 6 may be arranged at equal intervals in the circumferential direction.

[0062] In each of the above embodiments, the filling space S7 is a closed space that is closed off from the outside of the tire mold 1 when the tread mold 2 and the side mold 3 are assembled together. However, the filling space S7 may be an open space that is open to the outside of the tire mold 1 when the tread mold 2 and the side mold 3 are assembled together.

[0063] 1: tire mold, 2: tread mold, 2a: step in tread mold, 3: side mold, 3a: step in side mold, 4: bead mold, 5: through hole, 5a: one end of through hole, 5b: other end of through hole, 6: communicating groove, 6a: one end of communicating groove, 6b: other end of communicating groove, 7: recess, 7a: one end of recess, 7b: other end of recess, 10: spring vent, 11: shaft valve, 12: housing, 13: spring, F2: inner surface of tread mold, F21: tread side inner surface of tread mold, F22: shoulder side inner surface of tread mold, F3: inner surface of side mold, F31: shoulder side inner surface of side mold, F32, F33: sidewall side inner surface of side mold, F4: inner surface of bead mold, Fm2: tread mold side mating surface (tread mold mating surface), Fm21: tire radial direction inner mating surface of tread mold step, Fm22: tire axial direction inner mating surface of tread mold step, Fm3: tread side mold mating surface (side mold mating surface), Fm31: tire radial direction outer mating surface of side mold step, Fm32: tire axial direction outer mating surface of side mold step, O1: tire center axis, O2: tire radial axis, R6: communication passage, S7: filling space

Claims

1. A tire mold comprising a tread mold and a side mold, wherein an inner surface of the side mold, which is adjacent to a mating surface with the tread mold, is inclined inwardly toward the mating surface with the tread mold, a through hole is formed in the side mold, one end of the through hole opens to the inner surface of the mating surface with the side mold and the other end of the through hole opens to the mating surface with the tread mold, and a communication groove is formed in the mating surface with the tread mold, the communication groove having one end connected to the other end of the through hole and extending from the one end toward the outside of the side mold in the tire axial direction, the communication groove forming a communication passage leading to the through hole when the tread mold and the side mold are joined together, and further, a recess formed in a mating surface of the side mold with the tread mold, the recess communicating with the other end of the communicating groove, and the recess forming a filling space communicating with the communicating passage and having a volume larger than the total volume of the through hole and the communicating passage when the tread mold and the side mold are mated.

2. The tire mold according to claim 1, wherein the filling space is a closed space that is closed from the outside of the tire mold when the tread mold and the side mold are combined.

3. The tire mold according to claim 1 or 2, wherein a spring vent is disposed inside said through hole.

4. A tire mold as set forth in claim 1 or 2, wherein the recess is disposed at a position 20 mm or more outwardly in the tire axial direction from the inner end of the mating surface with the tread mold.

5. A tire mold as set forth in claim 1 or 2, wherein the through holes are disposed at positions 8 mm or less along the inner surface of the mating surface of the side mold from the inner edge of the mating surface with the tread mold.

Images