Tire molding die, method for producing tire and tire using the same

Abstract

To provide a tire molding die capable of performing efficient exhaust during vulcanization without affecting tire appearance or air resistance around a tire and to provide a method for producing a tire and a tire using the same.SOLUTION: There is provided a tire molding die 20 for forming a tire having a side plate 21 for forming a sidewall part 2 of the tire and a sector 23 for forming a tread part 1 of the tire in which a mounting direction with respect to a vehicle is specified, wherein an air vent slit 40 formed opening to the tire forming surface of each side plate 21 is provided on each of an inner side plate 21i for forming a sidewall part 2 inside of the vehicle and an outer side plate 21o for forming a sidewall part 2 outside of the vehicle and a slit 40 formed on the inner side plate 21i is disposed on an outer side in the tire radial direction of the slit 40 formed on the outer side plate 21o.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a tire molding mold for molding tires, a tire manufacturing method using the same, and tires; and more particularly, to a tire molding mold for molding tires that can suppress defects in tire appearance and reduce air resistance around the tire, a tire manufacturing method using the same, and tires. [Background technology]

[0002] Tire molds typically have vent holes (thin exhaust holes) for venting air during vulcanization. However, using vent holes for venting can result in rubber flowing into the holes, potentially creating spews, or whisker-like protrusions, on the surface of the molded tire. While these spews are typically removed before the tire is shipped, there's a risk that traces of the spew (cut marks) remain on the tire surface. In other words, the bases of the spews may remain as tiny cylindrical protrusions. The presence of these cut marks can negatively impact the tire's appearance, and the minute irregularities on the tire surface caused by the cut marks can affect air resistance around the tire. For this reason, Patent Document 1, for example, proposes reducing the number of vent holes by providing grooves on the mold's side molding surfaces as air vent channels. However, while these grooves can reduce the occurrence of spews, the rubber that flows into the air vent grooves remains on the tire as protrusions, potentially limiting their impact on air resistance. Therefore, further measures are needed to efficiently exhaust air during vulcanization without affecting the tire's appearance or the air resistance around the tire. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-305623 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a tire molding mold that makes it possible to improve the appearance of a tire after vulcanization and the air resistance around the tire while ensuring good exhaust performance, a tire manufacturing method using the same, and a tire. [Means for solving the problem]

[0005] In order to achieve the above object, the tire molding mold of the present invention is a tire molding mold for molding a tire for which the mounting direction on a vehicle is specified, and includes a pair of side plates for molding the sidewall portion of the tire and a sector for molding the tread portion of the tire, the pair of side plates including an inner side plate that molds the sidewall portion that will be on the inside of the vehicle when mounted on the vehicle, and an outer side plate that molds the sidewall portion that will be on the outside of the vehicle when mounted on the vehicle, each of the inner side plate and the outer side plate has an air vent slit that is formed so as to open on the tire molding surface of the respective side plate, the slit extends in the tire circumferential direction on each side plate, and the slit formed in the inner side plate is positioned radially outward of the slit formed in the outer side plate.

[0006] The tire manufacturing method of the present invention for achieving the above-mentioned object is a tire manufacturing method using the tire molding mold, characterized in that an unvulcanized tire is placed into the tire molding mold, and the unvulcanized tire is vulcanized in the tire molding mold while air is removed through the slits.

[0007] In addition, the tire of the present invention for achieving the above-mentioned object is a tire manufactured by the above-mentioned tire manufacturing method, and is characterized in that it has traces of the slits on at least a portion of the surface of the sidewall portion, and the traces of the slits on the sidewall portion on the inner side of the vehicle are positioned radially outward of the traces of the slits on the outer sidewall portion. [Effects of the Invention]

[0008] The inventors of the present invention conducted extensive research into exhaust methods for tire molds and discovered that by using a slit-shaped exhaust mechanism instead of conventional vent holes, it is possible to maintain good exhaust performance, prevent poor appearance, and reduce air resistance around the tire. Specifically, with conventional vent holes, rubber may flow into the vent holes, causing spew, and even if the spew is removed, there is a possibility of a cut mark (the base of the spew remaining as a tiny cylindrical protrusion). However, because the slit is a tiny gap, rubber is less likely to flow into it. Even if a mark remains due to rubber that has flowed into the slit, it is only a very thin, linear mark, so it does not detract from the tire's appearance or worsen air resistance around the tire. Meanwhile, the inventors of the present invention conducted extensive research into airflow around a vehicle while it is running and discovered that the inner sidewall portion of the tire, which is located inside the tire well when mounted on the vehicle, is affected by airflow flowing from the front under the vehicle and airflow generated in the gap between the vehicle side of the tire well and the tire tread. The present invention is a synthesis of these findings, and as described above, air vent slits are provided, particularly at appropriate positions on the inside and outside of the vehicle, thereby achieving excellent exhaust performance while preventing poor appearance and reducing air resistance around the tire.

[0009] Since the method for manufacturing the tire of the present invention uses the mold for tire molding of the present invention described above, the air remaining in the mold during vulcanization can be efficiently exhausted outside the mold through the slit. At this time, since the slit is a fine gap as described above, rubber does not substantially flow in, and even if a trace of the slit remains due to the rubber flowing into the slit, in the tire, only a linear trace with a fine width remains, so the appearance of the tire is not impaired, and the air resistance around the tire can be reduced.

[0010] Furthermore, since the tire (tire of the present invention) manufactured by the tire molding mold of the present invention is manufactured by the manufacturing method of the present invention described above, the trace of the slit for air venting substantially remains as described above, preventing appearance defects and reducing the air resistance around the tire.

[0011] In the tire molding mold of the present invention, it is preferable that the ratio h / H of the outer side plate satisfies the relationship of 0.2 ≤ h / H ≤ 0.7, and the ratio h / H of the inner side plate satisfies the relationship of 0 < h / H ≤ 0.4. By arranging the slit in this way, in the tire after vulcanization, in the sidewall portion on the outer side of the vehicle, since there is no trace of the exhaust mechanism near the maximum width position of the tire, the airflow generated at the outer edge of the vehicle can be rectified, and in the sidewall portion on the inner side of the vehicle, since there is no trace of the exhaust mechanism near the sector cut position, the turbulent flow generated in the tire house can be rectified, and the air resistance around the tire can be effectively reduced.

[0012] In the tire molding mold of the present invention, it is preferable that the width of the slit is 0.01 mm to 0.5 mm. By making the width of the slit sufficiently thin in this way, it is possible to reliably prevent the rubber from flowing in while maintaining the exhaust performance, which is advantageous for preventing appearance defects and reducing air resistance. In the present invention, the "width of the slit" is the dimension measured along the short side direction of the slit.

[0013] In the tire mold of the present invention, the slits preferably occupy 30% or more of the tire circumference at the positions in the tire radial direction where they are formed. By providing the slits with sufficient length in this manner, it becomes possible to exhibit good exhaust performance through the slits.

[0014] The tire mold of the present invention can also be configured to include a spare piece having at least one slit formed therein and a hole formed in the side plate into which the spare piece is inserted. This configuration makes it easier to clean the inside of the slit when cleaning the mold after vulcanization, thereby improving productivity. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a meridian cross-sectional view showing an example of a tire according to an embodiment of the present invention. [Figure 2] 1 is an explanatory diagram showing an example of a tire vulcanizing apparatus including a tire molding mold of the present invention. FIG. [Figure 3] FIG. 2 is an explanatory diagram showing an enlarged view of a main part of a tire molding mold according to an embodiment of the present invention. [Figure 4] FIG. 4 is an explanatory view showing an enlarged view of a main part of a tire mold according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] The configuration of the present invention will be described in detail below with reference to the accompanying drawings.

[0017] FIG. 1 shows an example of a tire manufactured using the tire vulcanization mold of the present invention (hereinafter referred to as the "tire of the present invention"). The tire of FIG. 1 is a pneumatic tire that includes a tread portion 1 that contacts the road surface, a pair of sidewall portions 2 arranged on both sides of the tread portion 1, and a pair of bead portions 3 arranged radially inward of the sidewall portions 2. This tire is designed so that the tire is mounted in a specified orientation when mounted on a vehicle. In FIG. 1, the symbol CL indicates the tire equator. Although not depicted in FIG. 1 because it is a meridian cross-section, the tread portion 1, sidewall portions 2, and bead portions 3 each extend circumferentially and form annular shapes, thereby forming the basic toroidal structure of a pneumatic tire. The following explanation using FIG. 1 will be based primarily on the meridian cross-section shown, but each tire component also extends circumferentially and forms an annular shape.

[0018] In the tire of FIG. 1, a carcass layer 4 is installed between a pair of left and right bead portions 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction and is folded back from the inner side to the outer side in the tire width direction around a bead core 5 arranged in each bead portion 3. A bead filler 6 is arranged on the outer periphery of the bead core 5, and this bead filler 6 is wrapped by the main portion and the folded back portion of the carcass layer 4. Meanwhile, a plurality of belt layers 7 (two layers in FIG. 1) are embedded on the outer periphery of the carcass layer 4 in the tread portion 1. Each belt layer 7 includes a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so as to cross each other between the layers. In these belt layers 7, the inclination angle of the reinforcing cords with respect to the tire circumferential direction is set, for example, in the range of 10° to 40°. Furthermore, at least one belt reinforcing layer 8 (two layers in FIG. 1) is provided on the outer periphery of the belt layer 7. The belt reinforcing layer 8 includes organic fiber cords oriented in the tire circumferential direction. In the belt reinforcing layer 8, the organic fiber cords are set at an angle of, for example, 0° to 5° with respect to the tire circumferential direction.

[0019] The tire of the present invention is a tire for which the mounting direction of the front and back of the tire when mounted on a vehicle is specified. In Fig. 1, "IN" indicates the inside of the vehicle when mounted on the vehicle, and "OUT" indicates the outside of the vehicle when mounted on the vehicle. A tire for which the mounting direction on a vehicle is specified has a mounting direction indicator (not shown) formed, for example, on at least the sidewall portion 2 on the outside of the vehicle, which indicates the mounting direction on the vehicle. The mounting direction indicator displays, for example, the character string "OUTSIDE" along the tire circumferential direction on the outside of the vehicle, and displays, for example, the character string "INSIDE" along the tire circumferential direction on the inside of the vehicle.

[0020] FIG. 2 shows an example of a tire vulcanizing apparatus including a tire vulcanizing mold (hereinafter, sometimes simply referred to as "mold") of the present invention. The tire vulcanizing apparatus comprises a mold 20 that molds the outer surface of the tire T, and a cylindrical bladder 30 that is inserted inside the pneumatic tire T. This tire vulcanizing apparatus also comprises a heating and pressurizing medium supply means (not shown) that supplies a heating and pressurizing medium such as steam into the bladder 30, and a heating means (not shown) that heats the mold 20. Note that the present invention mainly relates to an exhaust mechanism formed in the side plate 21 described below, and so the structure of the tire vulcanizing apparatus is not limited to the example shown in the figure, as long as it comprises the mold 20 (particularly the side plate and sector).

[0021] The mold 20 is composed of a pair of side plates 21 (a lower side plate 21A and an upper side plate 21B) for molding the sidewall portion of the tire, a pair of bead rings 22 (a lower bead ring 22A and an upper bead ring 22B) for molding the bead portion of the pneumatic tire T, and a plurality of sectors 23 for molding the tread portion of the pneumatic tire T, and the pneumatic tire T is vulcanized and molded inside the mold 20. Note that a mold for molding a tire whose mounting direction relative to a vehicle is specified is provided with protrusions and recesses corresponding to the above-mentioned mounting direction indicator (for example, protrusions and recesses with inverted character strings such as "OUTSIDE" or "INSIDE"), and these indicators make it possible to distinguish between the inside and outside of the vehicle in the tire.

[0022] The heating and pressurizing medium supply means (not shown) is configured to supply steam adjusted to a predetermined temperature and pressure and nitrogen gas adjusted to a predetermined pressure as the heating and pressurizing medium at appropriate times. When such heating and pressurizing medium is introduced into the bladder 30, the pressure of the heating and pressurizing medium presses the pneumatic tire T from the inside toward the inner surface of the mold 20. Note that it is also possible to use only steam as the heating and pressurizing medium.

[0023] The heating means (not shown) is attached to the lower side plate 21, the upper side plate 22, and the sector 23 that make up the mold 20, and the mold 20 is heated by the heating means to vulcanize the pneumatic tire T.

[0024] In the tire vulcanizing apparatus configured as described above, the tire molding mold (mold 20) of the present invention is provided with an air-bleeding slit 40 as shown in FIG. 3 on each of a pair of side plates 21 (lower side plate 21A and upper side plate 21B) for molding the sidewall portion 2 of the tire T. The air-bleeding slit 40 is a minute gap that opens on the tire molding surface of the side plate 21, and as shown in FIG. 3 , penetrates the mold 20 (side plate 21) and reaches an exhaust mechanism (not shown) inside the tire molding mold or the outside of the tire molding mold, thereby discharging air remaining in the mold during tire molding. The slit 40 also extends in the tire circumferential direction (the circumferential direction of the tire manufactured using this mold). A single slit 40 may be provided extending around the entire circumference of the tire, or multiple slits 40 may be provided intermittently around the tire. When the slit 40 extends in the tire circumferential direction, it may extend at an angle relative to the tire circumferential direction.

[0025] Unlike conventional vent holes (thin cylindrical exhaust holes), these air-release slits 40 do not allow rubber to flow into them, so spew does not occur as occurs with conventional vent holes. Even if traces of the slits 40 are formed due to rubber flowing into the slits 40, they are only fine linear traces, so they do not mar the appearance or worsen air resistance around the tire.

[0026] As described above, the slit 40 is a minute gap at the opening, and the width w of the slit 40 is preferably 0.01 mm to 0.5 mm, more preferably 0.02 mm to 0.05 mm. By making the width of the slit 40 sufficiently small, rubber does not substantially flow into the slit 40. Even if traces of the slit 40 remain due to the rubber that has flowed into the slit 40, they only remain as minute linear traces. This prevents damage to the tire's appearance and prevents poor appearance. If the width w of the slit 40 is smaller than 0.01 mm, it becomes difficult to ensure sufficient exhaust performance. Furthermore, the slit 40 is too thin, making it difficult to manufacture a mold (process the slit 40). If the width w of the slit 40 exceeds 0.5 mm, rubber tends to flow into the slit 40, leaving traces of the slit 40.

[0027] The present invention relates to the arrangement of the slits 40, and the tire radial positions of the slits 40 are different between the inner and outer sides of the tire. That is, when the pair of side plates (lower side plate 21A and upper side plate 21B) are classified into the inner side plate 21i, which forms the sidewall portion that will be on the inner side of the vehicle when mounted on the vehicle, and the outer side plate 21o, which forms the sidewall portion that will be on the outer side of the vehicle when mounted on the vehicle, taking into account the mounting direction of the tire, the slits 40 formed in the inner side plate 21i are positioned radially outward of the slits 40 formed in the outer side plate 21o. With this arrangement, the slits 40 formed in the outer side plate 21o are closer to the maximum width position of the tire, and the slits 40 formed in the inner side plate 21i are closer to the sector division position, thereby improving the airflow around the tire at each portion and effectively reducing air resistance around the tire. In addition, in Figure 2, the lower side plate 21A is depicted as the inner side plate 21i and the upper side plate 21B is depicted as the outer side plate 21o, but the combination of the lower side plate 21A and the upper side plate 21B with the inner side plate 21i and the outer side plate 21o is not particularly limited.

[0028] As described above, the positions of the slits 40 in the tire radial direction on the inner and outer sides of the vehicle are different. However, on either side, when the boundary position between the side plate 21 and the sector 23 is defined as the sector division position P, the ratio h / H of the tire radial distance H from this sector division position P to the position corresponding to the bead toe of the tire and the tire radial distance h from the sector division position P to the slit 40 preferably satisfies the relationship 0 < h / H ≤ 0.7. By providing the slit 40 at an appropriate position with respect to the sector division position P in this way, it is possible to exhibit excellent exhaust performance, prevent appearance defects, and reduce the air resistance around the tire. When the ratio h / H exceeds 0.7, the slit 40 is arranged radially inside the tire (particularly near the bead portion 3) from the maximum width position, making it difficult to appropriately exhaust the sidewall portion 2. Since the slit 40 cannot be processed on the sector division position P, the ratio h / H does not satisfy h / H = 0.

[0029] The above-mentioned ratio h / H preferably satisfies the relationship 0.2 ≤ h / H ≤ 0.7, more preferably 0.3 ≤ h / H ≤ 0.6, in the outer side plate 21o. As a result, the slit 40 of the outer side plate 21o is arranged near the maximum width position in the tire, and since there is no trace of the exhaust mechanism at this position in the tire, the airflow generated at the outer edge of the vehicle can be effectively rectified, and the air resistance around the tire can be effectively reduced. When the ratio h / H in the outer side plate 21o deviates from the above range, the slit 40 is separated from the maximum width position in the tire, so the effect of rectifying the airflow generated at the outer edge of the vehicle is limited.

[0030] Regarding the ratio h / H mentioned above, in the inner side plate 21i, it is preferably 0 < h / H ≤ 0.4, more preferably 0.04 ≤ h / H ≤ 0.25. In this way, the slit 40 of the inner side plate 21i is arranged near the sector division position P, and in the tire, there is no trace of the exhaust mechanism at this position, so the turbulent flow generated in the tire house can be effectively rectified, and the air resistance around the tire can be effectively reduced. If the ratio h / H in the inner side plate 21i is out of the above range, the slit 40 is separated from the sector division position P, so the effect of rectifying the turbulent flow generated in the tire house is limited.

[0031] In addition, when the slit 40 extends obliquely with respect to the tire circumferential direction, it is assumed that the relationship of the above ratio h / H is satisfied at any position of the slit 40 (the part farthest from the sector division position P of the slit 40 is also within the range of the above ratio h / H).

[0032] A plurality of slits 40 may be provided at positions satisfying the above ratio h / H. Also, one slit 40 extending over the entire circumference of the tire may be provided at a position satisfying the above ratio h / H. In either case, the total length of the slit 40 in the tire circumferential direction is preferably 30% or more, more preferably 50% or more of the tire circumferential length at the position where the slit 40 of the inner side plate 21i or the outer side plate 21o is formed. By providing the slit 40 with a sufficient length in this way, it becomes possible to excellently exhibit the exhaust performance by the slit 40. If the total length of the slit 40 in the tire circumferential direction is less than 30% of the tire circumferential length at the position where the slit 40 is formed, the length of the slit 40 cannot be sufficiently ensured, so there is a risk of deterioration of the exhaust performance.

[0033] The slit 40 may be formed directly in the mold 20 (side plate 21). Alternatively, as shown in FIG. 4, the side plate 21 may be configured to include a side plate main body 21a and a replacement piece 21b with the slit 40 formed therein, with the side plate main body 21a provided with a hole into which the replacement piece 21b is inserted. The replacement piece 21b is a component that is removably inserted into a hole formed in the side plate main body 21a. The molding surface of the side plate 21 is formed by inserting and fitting the replacement piece 21b into the hole. Note that FIG. 4 shows the replacement piece 21b inserted into the hole in the side plate main body 21a. In this configuration, the slit 40 can be formed at any position in the replacement piece 21b. However, as shown in the example, it is preferable to form the slit 40 by recessing the surface of the replacement piece 21b that abuts against the side of the hole when fitted. This configuration makes it easier to clean the inside of the slit 40 when cleaning the mold 20 (especially the side plate 21) after vulcanization, thereby improving productivity.

[0034] The slit 40 can be formed by any method (e.g., wire processing, laser processing, etc.) that can process a minute gap of the above-mentioned dimensions, whether it is formed directly in the side plate 21 or by using the replacement piece 21b as described above.

[0035] When manufacturing a tire using the tire mold described above, a typical method is used, that is, an unvulcanized tire is molded and then vulcanized in the tire mold described above. Air is removed from the mold using the slits 40 described above. Because the slits 40 are tiny gaps through which almost no rubber flows, the tire of the present invention generally leaves no traces of air removal on the surface of the sidewall portion 2 (the area where air is removed using the slits 40). Even if traces of the slits 40 are left behind due to rubber flowing into the slits 40, they are only small, linear traces in a certain area. Even if traces of the slits 40 are formed, they are not easily visible because, as described above, they are small, linear traces, and do not detract from the appearance of the sidewall portion 2. Furthermore, the traces of the slits 40 do not impair the air resistance around the tire.

[0036] As described above, a tire manufactured using the tire mold of the present invention (tire of the present invention) has substantially no traces of the air-bleeding slits remaining, preventing poor appearance and reducing air resistance around the tire. In particular, in the present invention, the arrangement of the slits 40 described above means that there are substantially no traces of the exhaust system at predetermined positions on each of the vehicle-inner and vehicle-outer sidewall portions 2 (near the maximum tire width position on the vehicle-outer sidewall portion 2 and near the sector division positions on the vehicle-inner sidewall portion 2), making it possible to rectify the airflow generated at the outer edge of the vehicle and the turbulence generated inside the tire housing, effectively reducing air resistance around the tire.

[0037] The present invention will be further explained below with reference to examples, but the scope of the present invention is not limited to these examples. [Example]

[0038] In manufacturing tires with a tire size of 245 / 50R19 95Y and having the structure illustrated in Fig. 1, the type of exhaust mechanism, width of the exhaust mechanism, length of the exhaust mechanism, ratio h / H, and method of forming the exhaust mechanism were varied for the tire molding mold, as shown in Tables 1 and 2 (Conventional Example 1, Comparative Examples 1 to 3, Examples 1 to 10). For each item, the settings for the inner side plate and the outer side plate are also listed.

[0039] In Tables 1 and 2, the column for "Type of exhaust mechanism" indicates whether a slit, vent hole, or circumferential groove was used as the exhaust mechanism. Note that a circumferential groove is a groove provided concentrically on the inner periphery of the sector division position, which connects vent holes to facilitate air flow, and is basically an exhaust mechanism used in combination with a vent hole as in Conventional Example 1 (Comparative Example 2 has only a circumferential groove, so it does not actually function as an exhaust mechanism, but is presented for comparison).

[0040] The "Exhaust mechanism width" column in Tables 1 and 2 lists the width of the exhaust mechanism used in each mold. Note that the vent hole width is essentially the diameter of the vent hole. The "Exhaust mechanism length" column lists the length of the exhaust mechanism used in each mold. The vent hole length is essentially the diameter of the vent hole and is listed as a real value (unit: mm). The length of the slits and circumferential grooves is the sum of their respective circumferential lengths, and is shown as a percentage (unit: %) of the tire circumference at the radial position where each exhaust mechanism is installed. In the "Exhaust mechanism width" and "Exhaust mechanism length" columns, if a combination of circumferential grooves and vent holes is used, the value for the circumferential groove is listed in the upper row of each column, and the value for the vent hole is listed in the lower row.

[0041] The "ratio h / H" column in Tables 1 and 2 is the ratio of the distance H in the tire's radial direction from the sector division position to the position corresponding to the tire's bead toe to the distance h in the tire's radial direction from the sector division position to the exhaust mechanism (slit, vent hole, circumferential groove). The "method of forming the exhaust mechanism" column indicates when the exhaust mechanism (slit, vent hole, circumferential groove) is directly formed on the side plate as "direct" and when a replacement piece with the exhaust mechanism formed on it is used as "replacement piece."

[0042] These examples were evaluated for appearance defect prevention, low air resistance, and workability using the following evaluation methods, and the results are shown in Tables 1 and 2.

[0043] Prevents appearance defects 1,000 tires were vulcanized using each tire mold, and the resulting tires were visually inspected to count the number of tires with visual defects (poor rubber flow or poor aesthetics due to incorrect vent cutting) and determine the incidence of visual defects. The evaluation results were expressed as an index using the reciprocal of the measured value, with Conventional Example 1's value being 100. The higher the index value, the fewer tires with visual defects, meaning better prevention of visual defects.

[0044] Low air resistance The pneumatic tires (test tires) manufactured using each tire molding mold were mounted on wheels with a rim size of 19 x 7.5J, the tire internal pressure was set to 230 kPa, and the tires were mounted on test vehicles. The vehicle speed while coasting was measured in accordance with JIS D1012, and the running resistance was calculated using the multipoint regression method. The evaluation results were expressed as an index using the reciprocal of the measured value, with Conventional Example 1's value being set at 100. The higher the index value, the lower the air resistance, indicating excellent low air resistance.

[0045] Workability The time required to clean the mold (exhaust mechanism) after vulcanizing a tire using each tire mold was measured. The evaluation results were expressed as an index using the reciprocal of the measured value, with Conventional Example 1's value being set at 100. The higher the index value, the shorter the time required to clean the mold, indicating better workability.

[0046] [Table 1]

[0047] [Table 2]

[0048] As is clear from Tables 1 and 2, when manufactured using the molds of Examples 1 to 8, the prevention of appearance defects and low air resistance were well maintained or improved compared to Conventional Example 1. On the other hand, in Comparative Example 1, only vent holes were provided, so cut marks were formed, and the prevention of appearance defects was reduced. In Comparative Example 2, only circumferential grooves were provided, so it did not actually function as an exhaust mechanism, and the prevention of appearance defects was reduced. In Comparative Example 3, the ratio h / H was the same for the inner side plate and the outer side plate 21, so the effect of reducing air resistance was not obtained.

[0049] The present disclosure includes the following inventions. Invention [1] A tire mold for molding a tire with a specified mounting direction on a vehicle, A tire tread mold includes a pair of side plates for molding a sidewall portion of the tire and a sector for molding a tread portion of the tire. the pair of side plates include an inner side plate that forms a sidewall portion that is on the inner side of the vehicle when mounted on the vehicle, and an outer side plate that forms a sidewall portion that is on the outer side of the vehicle when mounted on the vehicle, each of the inner side plate and the outer side plate has an air release slit formed to open to a tire molding surface of each side plate, the slit extending in a tire circumferential direction on each side plate; a slit formed in the inner side plate being positioned radially outward of the slit formed in the outer side plate; Invention [2] In each of the inner side plate and the outer side plate, the ratio h / H of the distance H in the tire radial direction from the sector division position, which is the boundary position between each side plate and the sector, to the position corresponding to the bead toe of the tire, and the distance h in the tire radial direction from the sector division position to the slit satisfies the relationship 0 < h / H ≤ 0.7. The tire molding die according to Invention [1]. Invention [3] The ratio h / H in the outer side plate satisfies the relationship 0.2 ≤ h / H ≤ 0.7, and the ratio h / H in the inner side plate satisfies the relationship 0 < h / H ≤ 0.4. The tire molding die according to Invention [2]. Invention [4] The width of the slit is 0.01 mm to 0.5 mm. The tire molding die according to any one of Inventions [1] to [3]. Invention [5] The total length of the slits in the tire circumferential direction is 30% or more of the tire circumferential length at the tire radial position where the slits are formed. The tire molding die according to any one of Inventions [1] to [4]. Invention [6] It includes a replacement piece in which at least one of the slits is formed, and a hole formed in the side plate into which the replacement piece is inserted. The tire molding die according to any one of Inventions [1] to [5]. Invention [7] A method for manufacturing a tire using the tire molding die according to any one of Inventions [1] to [6], comprising putting an unvulcanized tire into the tire molding die, and vulcanizing the unvulcanized tire in the tire molding die while performing air venting through the slit. A method for manufacturing a tire. Invention [8] A tire manufactured by the method for manufacturing a tire according to Invention [7], having traces of the slit on at least a part of the surface of the sidewall portion, where the traces of the slit in the sidewall portion on the inner side of the vehicle are arranged radially outside of the tire than the traces of the slit in the outer sidewall portion. A tire.

Explanation of reference numerals

[0050] 1 Tread section 2 Sidewall 3 Bead section 4 carcass layers 5 bead core 6 Bead filler 7 Belt Layer 8 Belt reinforcement layer 20 Mold 21 Side Plate 22 bead ring 23 sectors 30 Bladder 40 slits CL Tire Equator

Claims

1. A tire molding mold for molding a tire whose mounting direction on a vehicle is specified, A tire tread mold includes a pair of side plates for molding a sidewall portion of the tire and a sector for molding a tread portion of the tire. the pair of side plates include an inner side plate that forms a sidewall portion that is on the inner side of the vehicle when mounted on the vehicle, and an outer side plate that forms a sidewall portion that is on the outer side of the vehicle when mounted on the vehicle, each of the inner side plate and the outer side plate has an air release slit formed to open to a tire molding surface of each side plate, the slit extending in a tire circumferential direction on each side plate; a slit formed in the inner side plate being positioned radially outward of the slit formed in the outer side plate;

2. 2. The tire mold according to claim 1, wherein, in each of the inner side plate and the outer side plate, a ratio h / H of a distance H in the tire radial direction from a sector dividing position, which is a boundary position between each side plate and the sector, to a position corresponding to a bead toe of the tire, and a distance h in the tire radial direction from the sector dividing position to the slit, satisfies the relationship 0<h / H≦0.

7.

3. 3. The tire mold according to claim 2, wherein the ratio h / H of the outer side plate satisfies the relationship 0.2≦h / H≦0.7, and the ratio h / H of the inner side plate satisfies the relationship 0<h / H≦0.

4.

4. 2. The tire mold according to claim 1, wherein the width of the slit is 0.01 mm to 0.5 mm.

5. 2. The tire mold according to claim 1, wherein the total length of the slits in the tire circumferential direction is 30% or more of the tire circumferential length at the tire radial position where the slits are formed.

6. 2. The tire molding mold according to claim 1, further comprising: a spare piece having at least one of the slits formed therein; and a hole formed in the side plate into which the spare piece is inserted.

7. A tire manufacturing method using the tire molding mold according to any one of claims 1 to 6, characterized in that an unvulcanized tire is placed in the tire molding mold, and the unvulcanized tire is vulcanized in the tire molding mold while air is removed through the slits.

8. A tire manufactured by the tire manufacturing method according to claim 7, a trace of the slit on at least a part of the surface of the sidewall portion; A tire characterized in that the traces of the slits in the sidewall portion on an inner side of a vehicle are positioned radially outward of the traces of the slits in the outer sidewall portion.

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