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

Abstract

To provide a tire molding die capable of improving tire appearance and air resistance around a tire while exhibiting good exhaust performance 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 a tire and a sector 23 for forming a tread part 1 of the tire, wherein an air vent slit 40 extending in the tire circumference direction is provided on the tire forming surface of the side plate 21 and the ratio h / H of a distance h in the tire radial direction from the sector division position P to the slit 40 to a distance H in the tire radial direction from the sector division position P to the position corresponding to the tire bead toe is set to satisfy the relation of 0.04≤h / H≤0.25.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] Pneumatic tire structures can be broadly classified into cap-over-side structures (COS structures) and side-over-cap structures (SOC structures), depending on the lamination method of rubber (tread rubber and side rubber) used when molding an unvulcanized tire (see, for example, Patent Document 1). In the cap-over-side structure, the edge of the tread rubber (the rubber boundary) is exposed on the surface of the sidewall, making it prone to air trapping during vulcanization. Meanwhile, conventionally, vent holes (thin exhaust holes) have been provided to release air during vulcanization. However, when vent holes are used to exhaust air, rubber may flow into the vent holes, potentially creating spews, or whisker-like protrusions, on the tire surface after vulcanization. Such spews are removed before shipping as finished tires, but even after the spews are removed, traces (cut marks) of the spew removal may remain on the tire surface. In other words, the base of the spew may remain as a tiny cylindrical protrusion. The presence of such cut marks deteriorates the appearance of the tire, and minute irregularities on the tire surface caused by the cut marks may affect the air resistance around the tire. Therefore, measures are needed to efficiently exhaust air during vulcanization without affecting the tire appearance or the air resistance around the tire. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 06-182902 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 tire appearance and the air resistance around the tire while exhibiting 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 has side plates for molding the sidewall portions of a tire and sectors for molding the tread portion of the tire, and is characterized in that the tire mold is provided with an air-bleeding slit formed so as to open into the tire molding surface of the side plate, the slit extending in the tire circumferential direction, and the ratio h / H of the distance H in the tire radial direction from a sector dividing position, which is the boundary position between the side plate and the sector, to a position corresponding to the bead toe of the tire, to the distance h in the tire radial direction from the sector dividing position to the slit, satisfies the relationship 0.04≦h / H≦0.25.

[0006] The tire manufacturing method of the present invention for achieving the above 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 a slit.

[0007] Further, in order to achieve the above object, the tire of the present invention is a tire manufactured by the above tire manufacturing method, and is characterized in that it has traces of slits on at least a part of the surface of the sidewall portion. [Effects of the Invention]

[0008] The inventors of the present invention conducted extensive research into venting methods for tire molds and discovered that by using a slit-shaped vent mechanism instead of conventional vent holes, it is possible to maintain good venting 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 slits are tiny gaps, rubber is less likely to flow into them. Even if a mark remains due to rubber that has flowed into the slit, it is only a very thin, linear mark, so the tire appearance is not impaired and air resistance around the tire is not adversely affected. The present invention is based on this discovery. By providing air-venting slits as described above, particularly at appropriate positions relative to the sector division positions, it is possible to prevent poor appearance and reduce air resistance around the tire while maintaining excellent venting performance.

[0009] The tire manufacturing method of the present invention uses the tire mold of the present invention described above, and therefore air remaining in the mold during vulcanization can be efficiently vented to the outside of the mold through the slits. At this time, since the slits are minute gaps as described above, rubber does not substantially flow into them, and even if traces of the slits remain due to the rubber that has flowed into them, only fine linear traces remain in the tire, so the appearance of the tire is not impaired and air resistance around the tire can be reduced.

[0010] Furthermore, since the tire manufactured using the tire molding mold of the present invention (tire of the present invention) is manufactured by the manufacturing method of the present invention described above, substantially no traces of the air vent slits remain, as described above, preventing poor appearance and reducing air resistance around the tire.

[0011] In the tire mold of the present invention, the slit width is preferably 0.01 mm to 0.5 mm. By making the slit width sufficiently thin, it is possible to reliably prevent the inflow of rubber while maintaining exhaust performance, which is advantageous for preventing poor appearance and reducing air resistance. In the present invention, the "slit width" refers to the dimension measured along the short side of the slit.

[0012] In the tire mold of the present invention, the total length of the slits in the tire circumferential direction is preferably 30% or more of the tire circumference at the sector division position. By providing the slits with a sufficient length in this manner, it is possible to achieve good exhaust performance through the slits.

[0013] In the tire molding mold of the present invention, a knurled portion protruding from the tire molding surface between the sector dividing position and the slit can be provided on the tire molding surface, and both ends of the knurled portion in the tire radial direction can be in contact with the sector dividing position and the slit, respectively. In this configuration, the provision of the knurled portion can improve the flow of rubber within the mold, preventing poor appearance and being advantageous for reducing air resistance around the tire.

[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.

[0015] In the tire manufacturing method of the present invention, the unvulcanized tire preferably has a structure in which the tread rubber layer constituting the tread portion is laminated so as to cover the outer peripheral side of the side rubber layer constituting the sidewall portion. When a tire is manufactured from such an unvulcanized tire, the end portion (rubber boundary) of the tread rubber layer is exposed on the surface of the sidewall portion, and air tends to easily become trapped during vulcanization. Therefore, using the slits for exhausting air is advantageous in achieving good exhaustion, preventing poor appearance, and reducing air resistance at the same time.

[0016] In the tire of the present invention, it is preferable that at least a part of the surface of the sidewall portion has traces of slits, and that the edge of the tread rubber layer in the tire width direction is located between the sector division position and the trace of the slit. As mentioned above, if the edge of the tread rubber layer in the tire width direction (rubber boundary) is exposed on the surface of the sidewall portion, it becomes a location where air is likely to accumulate, so by locating the edge of the tread rubber layer in an appropriate position with respect to the sector division position and the slit position as described above, it is advantageous to achieve good exhaust, prevention of poor appearance, and reduction of air resistance at the same time. [Brief explanation of the drawings]

[0017] [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

[0018] The configuration of the present invention will be described in detail below with reference to the accompanying drawings.

[0019] 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. 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 in the tire direction and form an annular shape, thereby forming the basic toroidal structure of a pneumatic tire. The following explanation using FIG. 1 will be based essentially on the meridian cross-section shown, but each tire component also extends circumferentially in the tire direction and forms an annular shape.

[0020] 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.

[0021] In the tread portion 1, a tread rubber layer 11 is disposed on the outer peripheral side of the carcass layer 4, belt layer 7, and belt reinforcing layer 8. The tread rubber layer 11 may have a structure in which two types of rubber layers with different physical properties (a cap tread layer that forms the tread surface of the tread portion 1 and an under tread layer disposed on its inner peripheral side) are laminated in the tire radial direction. A side rubber layer 12 is disposed on the outer peripheral side (outer side in the tire width direction) of the carcass layer 4 in the sidewall portion 2, and a rim cushion rubber layer 13 is disposed on the outer peripheral side (outer side in the tire width direction) of the carcass layer 4 in the bead portion 3.

[0022] 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).

[0023] The mold 20 is composed of a pair of side plates 21 (lower side plate 21A and upper side plate 21B) for molding the sidewall portion of the tire, a pair of bead rings 22 (lower bead ring 22A and 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.

[0024] 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.

[0025] 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.

[0026] In the tire vulcanization 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, in at least one 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) within 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.

[0027] 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.

[0028] 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.

[0029] The present invention relates to the arrangement of the slits 40. Specifically, when the boundary between the side plate 21 and the sector 23 is defined as the sector dividing position P, the ratio h / H of the radial distance H from the sector dividing position P to the position corresponding to the bead toe of the tire and the radial distance h from the sector dividing position P to the slit satisfies the relationship 0.04≦h / H≦0.25, preferably 0.08≦h / H≦0.20. By locating the slits 40 at an appropriate position relative to the sector dividing position P, it is possible to achieve excellent exhaust performance, prevent poor appearance, and reduce air resistance around the tire. If the ratio h / H is less than 0.04, the slits 40 will be located too close to the edge of the side plate 21, making it difficult to manufacture a mold (to process the slits 40). If the ratio h / H is greater than 0.25, it becomes difficult to achieve good exhaust performance. Furthermore, when the slit 40 extends at an angle relative to the tire circumferential direction, the above-mentioned ratio h / H relationship is satisfied at any position of the slit 40 (the portion of the slit 40 farthest from the sector division position P is also within the range of the above-mentioned ratio h / H).

[0030] A plurality of slits 40 may be provided at positions that satisfy the above-described ratio h / H. Alternatively, a single slit 40 may be provided at a position that satisfies the above-described ratio h / H and extends around the entire tire circumference. In either case, the total circumferential length of the slits 40 is preferably 30% or more, more preferably 50% or more, of the tire circumference at the sector dividing position P. By providing the slits 40 with a sufficient length in this manner, the exhaust performance of the slits 40 can be favorably exhibited. If the total circumferential length of the slits 40 is less than 30% of the tire circumference at the sector dividing position P, the slits 40 may not be long enough, which may result in a decrease in exhaust performance. Note that when a single slit 40 is provided around the entire tire circumference, the slit 40 is provided concentrically inside the sector dividing position, and therefore its length is less than 100% of the tire circumference at the sector dividing position P, for example, 95% or less.

[0031] 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.

[0032] 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.

[0033] The mold 20 of the present invention can also be configured to have a knurled portion (not shown) consisting of a repeating pattern of minute projections and depressions on the tire molding surface between the sector dividing position P and the slit 40. In particular, it is preferable that the knurled portion protrude from the tire molding surface, and that both ends of the knurled portion in the tire radial direction contact the sector dividing position P and the slit 40, respectively. Providing the knurled portion in this manner can improve the flow of rubber within the mold, preventing poor appearance and being advantageous for reducing air resistance around the tire. Furthermore, by having both ends of the knurled portion in the tire radial direction contact the sector dividing position P and the slit 40, respectively, it is possible to improve the flow of air into the slit 40, which serves as an exhaust mechanism. In addition, if the knurled portion protrudes from the tire molding surface, a recess recessed from the surface of the sidewall portion 2 is formed in the tire, thereby not compromising the effect of reducing air resistance.

[0034] 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.

[0035] Any tire can be manufactured by the above method, but the unvulcanized tire preferably has a structure in which the tread rubber layer 11 constituting the tread portion 1 is laminated so as to cover the outer periphery of the side rubber layer 12 constituting the sidewall portion 12 (so-called cap-over-side structure). That is, when a tire is manufactured from such an unvulcanized tire, the end portion (rubber boundary) of the tread rubber layer 11 is exposed on the surface of the sidewall portion 2, and air tends to become trapped during vulcanization. Therefore, by venting the air using the slits 40 provided at the above-mentioned positions, it is possible to effectively prevent poor appearance and reduce air resistance.

[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, thereby preventing poor appearance and reducing air resistance around the tire. When traces of the slits are present on at least a portion of the surface of the sidewall portion, it is preferable that the tire width direction end of the tread rubber layer be located between the sector division position and the slit traces. As described above, if the tire width direction end (rubber boundary) of the tread rubber layer is exposed on the surface of the sidewall portion, it becomes a location where air is likely to accumulate. Therefore, locating the end of the tread rubber layer in an appropriate position relative to the sector division position and the slit position as described above is advantageous for achieving good exhaust, preventing poor appearance, and reducing air resistance at the same time.

[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 having a tire size of 245 / 50R19 95Y and the structure illustrated in FIG. 1, the type of exhaust mechanism, the width of the exhaust mechanism, the length of the exhaust mechanism, the ratio h / H, the presence or absence of a knurled portion, and the method of forming the exhaust mechanism were varied for the tire molding mold, as shown in Tables 1 to 2 (Conventional Example 1, Comparative Examples 1 to 4, and Examples 1 to 10).

[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] In Tables 1 and 2, the "Exhaust mechanism width" column 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 lengths in the circumferential direction of the tire, and is shown as a percentage (unit: %) of the tire circumference at the sector division position. 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 Table 1 is the ratio of the radial distance H from the sector division position to the position corresponding to the tire's bead toe to the radial distance h from the sector division position to the exhaust mechanism (slit, vent hole, circumferential groove). The "Presence or Absence of Knurling" column indicates "Present" if a knurling is provided on the tire molding surface between the sector division position and the slit, and "Absent" if it is not. The "Exhaust Mechanism Forming Method" column indicates "Direct Mount" if the exhaust mechanism (slit, vent hole, circumferential groove) is directly formed on the side plate, and "Replacement Plate" if a replacement plate with an exhaust mechanism formed on it is used.

[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 10, air resistance was reduced while preventing appearance defects to the same extent or better than Conventional Example 1, and excellent workability was demonstrated. On the other hand, Comparative Example 1 had reduced appearance defect prevention capabilities because only vent holes were provided. Comparative Example 2 had reduced appearance defect prevention capabilities because only circumferential grooves were provided. Comparative Example 3 had reduced appearance defect prevention capabilities because the ratio h / H was too small. Comparative Example 4 had reduced appearance defect prevention capabilities because the ratio h / H was too large.

[0049] The present disclosure encompasses the following inventions. Invention [1] A tire molding mold having side plates for molding the sidewall portion of a tire and sectors for molding the tread portion of a tire, an air vent slit formed to open on the tire molding surface of the side plate, the slit extending in the tire circumferential direction; a ratio h / H of a distance H in the tire radial direction from a sector dividing position, which is a boundary position between the side plate and the sector, to a position corresponding to a bead toe of the tire, to a distance h in the tire radial direction from the sector dividing position to the slit, satisfying the relationship 0.04≦h / H≦0.25. Invention [2] The tire mold according to invention [1], wherein the width of the slit is 0.01 mm to 0.5 mm. Invention [3] A tire molding mold according to invention [1] or [2], characterized in that the total length of the slits in the tire circumferential direction is 30% or more of the tire circumference at the sector division position. Invention [4] A tire molding mold according to any one of inventions [1] to [3], characterized in that a knurled portion protruding from the tire molding surface is provided on the tire molding surface between the sector dividing position and the slit, and both ends of the knurled portion in the tire radial direction are in contact with the sector dividing position and the slit, respectively. Invention [5] A tire molding mold according to any one of inventions [1] to [4], characterized in that it comprises a spare piece in which at least one of the slits is formed, and a hole formed in the side plate into which the spare piece is inserted. Invention [6] A method for manufacturing a tire using a tire mold according to any one of Inventions [1] to [5], characterized in that an unvulcanized tire is placed in the tire mold, and the unvulcanized tire is vulcanized in the tire mold while air is removed through the slit. Invention [7] The unvulcanized tire has a structure in which a tread rubber layer constituting the tread portion is laminated so as to cover the outer peripheral side of a side rubber layer constituting the sidewall portion, according to the method for manufacturing a tire described in Invention [6]. Invention [8] A tire manufactured by the tire manufacturing method according to invention [6] or [7], A tire having traces of the slits on at least a portion of the surface of the sidewall portion. Invention [9] A tire manufactured by the tire manufacturing method according to Invention [7], a trace of the slit on at least a part of the surface of the sidewall portion; A tire characterized in that an end portion in the tire width direction of the tread rubber layer is located between the sector division position and the slit trace. [Explanation of symbols]

[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 mold having side plates for molding a sidewall portion of a tire and sectors for molding a tread portion of the tire, an air vent slit formed to open on the tire molding surface of the side plate, the slit extending in the tire circumferential direction; a ratio h / H of a distance H in the tire radial direction from a sector dividing position, which is a boundary position between the side plate and the sector, to a position corresponding to a bead toe of the tire, to a distance h in the tire radial direction from the sector dividing position to the slit, satisfying the relationship 0.04≦h / H≦0.

25.

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

3. 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 circumference at the sector dividing position.

4. 2. The tire molding mold according to claim 1, wherein a knurled portion protruding from the tire molding surface is provided on the tire molding surface between the sector dividing position and the slit, and both ends of the knurled portion in the tire radial direction are in contact with the sector dividing position and the slit, respectively.

5. 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.

6. A tire manufacturing method using the tire molding mold according to any one of claims 1 to 5, 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.

7. 7. The tire manufacturing method according to claim 6, wherein the unvulcanized tire has a structure in which a tread rubber layer constituting the tread portion is laminated so as to cover an outer peripheral side of a side rubber layer constituting the sidewall portion.

8. A tire manufactured by the tire manufacturing method according to claim 6, A tire having traces of the slits on at least a portion of the surface of the sidewall portion.

9. 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 an end portion in the tire width direction of the tread rubber layer is located between the sector division position and the slit trace.

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