Tire molding die, tire manufacturing method using the same, and tire

Abstract

To provide a tire molding die capable, while maintaining superior exhaust performance, of preventing defect in the exterior and obtaining air resistance reduction performance, and a tire manufacturing method using the same, and a tire.SOLUTION: A tire molding die for molding a tire in which plural protrusions having a longitudinal direction in a surface of a tire side part are disposed at intervals in a tire peripheral direction, includes recesses for forming the protrusions and an air-bleeding slit formed so as to open on an inner face of the respective recesses.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a tire molding mold for molding a tire having a plurality of longitudinally extending convex portions on the surface of a tire side portion, a tire manufacturing method using the same, and a tire. [Background technology]

[0002] In recent years, in order to reduce the air resistance of a vehicle by changing the air flow around the tire, a plurality of convex portions (so-called "fins") having a longitudinal direction are provided on the surface of the tire side portion (see, for example, Patent Document 1). A tire molding die for manufacturing such a tire has a concave portion corresponding to the convex portion, and in order to exhaust the air accumulated in the concave portion to the outside of the die and obtain a convex portion of an appropriate shape, a vent hole (thin exhaust hole) may be provided in the concave portion. However, when exhausting air using a vent hole, there is a risk that rubber flows into the vent hole and spews, which are whisker-like protrusions, are generated on the surface of the convex portion. Such spews are cut off before being shipped as a product tire, but even if the spews are cut off, there is a risk that traces (cut marks) of the spews being cut off remain on the surface of the convex portion. In other words, there is a possibility that the root portion of the spews remains as fine cylindrical protrusions. If such cut marks exist, the appearance of the convex portion is deteriorated, and there is a problem that the effect of reducing air resistance is not sufficiently obtained due to the fine unevenness on the surface of the convex portion caused by the cut marks. Therefore, there is a demand for measures to prevent poor appearance while maintaining excellent exhaust performance and to obtain excellent air resistance reduction performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-511096 A 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 prevents poor appearance while maintaining excellent exhaust performance, and makes it possible to obtain excellent air resistance reduction performance, as well as a tire manufacturing method and tire using the same. [Means for solving the problem]

[0005] In order to achieve the above-mentioned object, the tire molding mold of the present invention is a tire molding mold for molding a tire having a plurality of longitudinally extending protrusions on the surface of a tire side portion that are spaced apart in the tire circumferential direction, the tire molding mold being characterized by comprising a recess for forming the protrusions, and an air vent slit formed to open on the inner surface of the recess.

[0006] The tire manufacturing method of the present invention for achieving the above-mentioned object is a tire manufacturing method using the above-mentioned tire molding mold, characterized in that a tire in an unvulcanized state is molded and the tire is vulcanized in the above-mentioned tire molding mold of the present invention.

[0007] In addition, in order to achieve the above-mentioned object, the tire of the present invention is a tire having a plurality of longitudinally extending convex portions on the surface of the tire side portion, the plurality of convex portions being spaced apart in the circumferential direction of the tire, and characterized in that less than half of the plurality of convex portions have traces of air-bleeding slits on the surface of the plurality of convex portions. Effect of the Invention

[0008] As described above, the tire molding die of the present invention is for manufacturing a tire having a plurality of longitudinally extending convex portions arranged at intervals in the tire circumferential direction on the surface of the tire side portion, and since slits are provided instead of conventional vent holes to exhaust air accumulated in the concave portions for molding the convex portions to the outside of the die, it is possible to prevent poor appearance while maintaining good exhaust properties. That is, with conventional vent holes, there is a risk that rubber will flow into the vent hole and cause a spew, and even if the spew is cut off, there is a possibility that a cut mark (the base part of the spew remaining as a fine cylindrical protrusion) will remain, but since the slit is a fine gap, rubber is unlikely to flow into it, and even if a mark of the slit remains due to the rubber that has flowed into the slit, only a fine linear mark remains, so the appearance is not impaired and poor appearance can be prevented.

[0009] In addition, because the tire manufacturing method of the present invention uses the tire molding mold of the present invention described above, air remaining in the mold (particularly in the recesses) during vulcanization can be efficiently exhausted 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 the slits, only minute linear traces remain on the tire, so the appearance is not impaired and poor appearance can be prevented.

[0010] Furthermore, a tire manufactured using the tire molding die of the present invention (tire of the present invention) has a plurality of longitudinally extending convex portions on the surface of the tire side portion as described above, and the convex portions that rotate and move when the vehicle is running turbulently cause the air to flow, improving stagnation of the air flow around the tire and reducing the air resistance of the vehicle. Even if traces of the air-bleeding slits remain on the surface of the convex portions, the traces of the slits are fine linear traces as described above, so the shape of the convex portions is not marred by the traces of the slits, and the air resistance reduction performance can be satisfactorily exhibited.

[0011] In the tire molding die of the present invention, it is preferable that the slits extend along the longitudinal direction of the recesses. By aligning the longitudinal direction of the protrusions and the extension direction of the slit traces (linear traces) in this way, the slit traces become less noticeable, which is advantageous in preventing poor appearance.

[0012] In the tire molding die of the present invention, the slit is preferably disposed at a portion where the depth of the recess is greatest. By disposing the slit at a position in the recess where air is most likely to remain, it is advantageous for improving exhaust performance.

[0013] In the tire molding die of the present invention, the width of the slit is preferably 0.01 mm to 0.5 mm. Making the width of the slit sufficiently thin in this manner is advantageous for preventing poor appearance and improving air resistance reduction performance. In the present invention, the "width of the slit" refers to the length measured along the short side direction of the slit.

[0014] In the tire molding die of the present invention, the length of the slit is preferably 2% to 100% of the length of the recess. By providing a slit of an appropriate length relative to the recess in this manner, it is advantageous to prevent poor appearance and improve air resistance reduction performance while ensuring exhaust performance. In the present invention, the "length of the slit" is the length measured along the longitudinal direction of the slit.

[0015] In the tire molding die of the present invention, the opening area of ​​the slit is preferably 0.01% to 15% of the opening area of ​​the recess. By providing the slit with an appropriate length relative to the recess in this manner, it is advantageous to prevent poor appearance and improve air resistance reduction performance while ensuring exhaust performance.

[0016] The tire molding mold of the present invention can also be used with a replacement piece having a slit formed therein and a fixing hole into which the replacement piece is fitted. In this specification, it is preferable that the surface of the replacement piece that abuts against the side surface of the fixing hole is recessed relative to the side surface of the fixing hole against which it abuts when fitted, thereby forming the slit. In this specification, cleaning inside the slit becomes easier when cleaning the mold after vulcanization, and productivity can be improved. [Brief description 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. [Diagram 2] 1 is a side view showing an example of a tire according to an embodiment of the present invention. [Diagram 3] 3 is a schematic diagram of a protrusion extracted from part X in FIG. 2. FIG. [Figure 4] FIG. 1 is an explanatory diagram showing an example of a tire vulcanizing apparatus. [Diagram 5] FIG. 2 is a front view showing a schematic diagram of a recess of a tire vulcanizing mold according to an embodiment of the present invention. [Figure 6] FIG. 2 is an explanatory diagram illustrating a recess of a tire vulcanizing mold according to an embodiment of the present invention. [Figure 7] FIG. 4 is an explanatory view showing a schematic diagram of a recess of a tire vulcanization mold according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 by 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, and 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 on the tire radial inner side 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, the sidewall portions 2, and the bead portions 3 each extend in the tire circumferential direction to form an annular shape, and thus the toroidal basic structure of the pneumatic tire is constituted. The following description using FIG. 1 is basically based on the meridian cross section shown in the figure, but each tire component extends in the tire circumferential direction to form 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 the bead cores 5 arranged in each bead portion 3. A bead filler 6 is arranged on the outer periphery of the bead cores 5, and the bead filler 6 is wrapped by the main body 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 side 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 to, for example, a range of 10° to 40°. Furthermore, at least one belt reinforcing layer 8 (two layers in FIG. 1) is provided on the outer periphery side 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] FIG. 2 is a side view of the tire of the present invention. As shown in FIG. 2, a plurality of protrusions 9 (fins) having a longitudinal direction are provided at intervals in the tire circumferential direction on the surface of the tire side portion (sidewall portion 2) of the tire of the present invention. The protrusions 9 may be provided on the tire radially inward (bead portion 3 side) of the tire maximum width position as in the illustrated example, or on the tire radially outward (tread portion 1 side) of the tire maximum width position as opposed to the illustrated example, and can be provided at any position in the tire radial direction of the sidewall portion 2. The protrusions 9 are protrusions integrally formed with the tire side portion. In the illustrated example, the protrusions 9 are formed as ridges extending intersecting the tire circumferential direction and the tire radial direction on the surface of the tire side portion. In the illustrated example, the protrusions 9 are formed to be curved in a side view of the pneumatic tire 1, but are not limited to this shape, and may be formed to be straight, bent, S-shaped, meandering, or zigzag.

[0022] By providing the surface of the tire side portion with multiple protrusions 9 in the longitudinal direction in this manner, the protrusions 9 that rotate and move when the vehicle is traveling turbulently create airflow, improving stagnation of the air flow around the tire and reducing the air resistance of the vehicle. The multiple protrusions 9 are preferably provided on at least one of the tire side portions on both sides in the tire width direction. In particular, it is preferable to provide them on the tire side portion that is on the outer side of the vehicle when the tire is mounted on the vehicle.

[0023] The specific shape of the protrusion 9 is not particularly limited, but may be a three-dimensional shape consisting of multiple faces (two faces in the illustrated example) facing different directions and a ridge line located at the boundary between these faces, as shown in Fig. 3. In a cross section of the protrusion at any position perpendicular to the ridge line, a point on the ridge line is the apex of the protrusion. By making the shape have multiple faces and ridge lines in this way, the air around the tire can be efficiently turbulent, which is advantageous for reducing the air resistance of the vehicle.

[0024] The present invention relates to a tire having a plurality of protrusions 9 on the surface of the tire side portion as described above, a tire molding die for molding the tire, and a tire manufacturing method using the tire molding die. Therefore, the basic structure of the tire of the present invention is not limited to the above example as long as the plurality of protrusions 9 are provided on the surface of the tire side portion as described above. In addition, the tire of the present invention may be a non-pneumatic tire as long as the plurality of protrusions 9 are provided on the surface of the tire side portion as described above.

[0025] FIG. 4 shows an example of a tire vulcanizing apparatus including a tire vulcanizing mold (hereinafter, sometimes simply referred to as a "mold") of the present invention. The tire vulcanizing apparatus includes a mold 10 for molding the outer surface of the tire T, and a cylindrical bladder 20 inserted inside the pneumatic tire T. The tire vulcanizing apparatus also includes a heating and pressurizing medium supplying means (not shown) for supplying a heating and pressurizing medium such as steam into the bladder 20, and a heating means (not shown) for heating the mold 10. Note that the present invention relates to a convex portion formed in a tire side portion, and therefore the tire vulcanizing apparatus is not limited to the example shown in the figure as long as it has a molding surface for molding a sidewall portion.

[0026] The mold 10 is composed of a pair of side plates 11 (lower side plate 11A and upper side plate 11B) for molding the sidewall portion of the tire, a pair of bead rings 12 (lower bead ring 12A and upper bead ring 12B) for molding the bead portion of the pneumatic tire T, and a plurality of sectors 13 for molding the tread portion of the pneumatic tire T, and the pneumatic tire T is vulcanized and molded inside the mold 10.

[0027] The heating and pressurizing medium supplying means (not shown) is adapted 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 a heating and pressurizing medium is introduced into the bladder 20, the pneumatic tire T is pressed from the inside toward the inner surface of the mold 10 based on the pressure. It is also possible to use only steam as the heating and pressurizing medium.

[0028] Heating means (not shown) is attached to the lower side plate 11, the upper side plate 12, and the sector 13 that constitute the mold 10, and the mold 10 is heated by the heating means to vulcanize the pneumatic tire T.

[0029] In the tire vulcanizing apparatus thus configured, the tire molding die (mold 10) of the present invention, particularly at least one of the pair of side plates 11 (lower side plate 11A and upper side plate 11B) for molding the sidewall portion, is provided with recesses 30 for forming protrusions 9 (fins) in the tire, as shown in Figures 5 and 6. As the protrusions have a shape having a longitudinal direction as described above, and multiple protrusions are arranged at intervals in the tire circumferential direction on the surface of the tire side portion, multiple recesses 30 are similarly arranged at intervals in the tire circumferential direction on the surface of the die 10 (side plate 11) for molding the sidewall portion 2.

[0030] In the tire molding die of the present invention, the recess 30 is provided with a slit 31 for venting air, which is formed so as to open to the inner surface of the recess 30. As shown in Fig. 6, the slit 31 penetrates the die 10 (side plate 11) and reaches an exhaust mechanism (not shown) in the tire molding die or the outside of the tire molding die, and discharges air remaining in the die during tire molding. In the illustrated example, the slit 31 extends along the longitudinal direction of the recess 30. In this way, since the slit 31 is provided instead of a conventional vent hole (a thin cylindrical exhaust hole), it is possible to prevent poor appearance while maintaining good exhaust properties. That is, with conventional vent holes, there was a risk that rubber would flow into the vent hole and cause a spew, and even if the spew was removed, there was a possibility that a cut mark (the base of the spew remaining as a tiny cylindrical protrusion) would remain. However, because slits 31 are tiny gaps, almost no rubber flows into them, and even if a mark of slit 31 is formed due to rubber that has flowed into slit 31, only a very narrow linear mark remains, so the appearance is not marred and poor appearance can be prevented.

[0031] As described above, the slit 31 is a gap with a very small width at the opening, and the width w of the slit 31 is preferably 0.01 mm to 0.5 mm, more preferably 0.02 mm to 0.05 mm. When the width of the slit 31 is sufficiently small, the rubber does not substantially flow into the slit 31, and even if a trace of the slit remains due to the rubber that has flowed into the slit 31, only a very small linear trace remains, so that the appearance is not impaired and poor appearance can be prevented. If the width w of the slit 31 is smaller than 0.01 mm, it is difficult to ensure sufficient exhaust performance. In addition, since the slit 31 is too thin, it is difficult to manufacture the mold (machining the slit 31). If the width w of the slit 31 exceeds 0.5 mm, the rubber easily flows into the slit 31 and the trace of the slit 31 is easily left.

[0032] In order to ensure exhaust performance equal to or greater than that of a conventional vent hole, the slit 31 should be sufficiently open. In order to ensure an opening area while maintaining a fine width of the slit 31, the slit 31 should have a sufficient length. Specifically, the length L1 of the slit 31 is preferably 2% to 100% of the length L0 of the recess, more preferably 5% to 30%. By providing the slit 31 with an appropriate length relative to the recess 30 in this manner, it is advantageous to prevent poor appearance and improve air resistance reduction performance while ensuring exhaust performance. If the length L1 of the slit 31 is less than 2% of the length L0 of the recess 30, the opening area of ​​the slit 31 cannot be sufficiently ensured, making it difficult to maintain good exhaust performance. If the length L1 of the slit 31 exceeds 100% of the length L0 of the recess 30, the slit 31 will extend beyond the recess 30, making it difficult to manufacture a mold (machining the slit 31).

[0033] In addition to the width and length of the slit 31 satisfying the above relationship, the opening area of ​​the slit 31 is preferably 0.01% to 15% of the opening area of ​​the recess 30, more preferably 0.1% to 5%. By providing the slit 31 with an appropriate width relative to the recess 30 in this manner, it is advantageous to prevent poor appearance and improve air resistance reduction performance while ensuring exhaust performance. If the opening area of ​​the slit 31 is less than 0.01% of the opening area of ​​the recess 30, it is difficult to ensure sufficient exhaust performance. If the opening area of ​​the slit 31 exceeds 15% of the opening area of ​​the recess 30, there is a risk that the trace of the slit 31 will be large, and there is a risk that the appearance of the protrusion 9 of the tire and the air resistance reduction effect of the protrusion 9 will be reduced when the tire is manufactured.

[0034] The slits 31 can be provided at any position on the inner surface of the recess 30, but as in the illustrated example, it is preferable that the slits 31 extend along the longitudinal direction of the recess 30. By providing the slits 31 in this way, the longitudinal direction of the protrusions 9 and the extension direction of the traces (linear traces) of the slits 31 are aligned in the tire, so that the traces of the slits 31 are less noticeable, which is advantageous for preventing poor appearance. In addition, in consideration of the flow of rubber during molding, it is preferable to provide the slits 31 in the deepest part (the part with the greatest depth) of the recess 30. By providing the slits 31 in the position (deepest part) in the recess 30 where air is most likely to remain, it is advantageous for improving exhaust performance.

[0035] The recess 30 shown in Figures 5 and 6 is intended to mold the protrusion 9 shown in Figures 2 and 3, and has two molding surfaces for molding the two surfaces of the protrusion 9. The boundary line connecting these two molding surfaces corresponds to the ridge line of the protrusion 9, and is the deepest part of the recess 30. In the case of such a recess 30, it is preferable to arrange the slit 31 on the boundary line corresponding to the ridge line. This allows the trace of the slit 31 to be substantially integrated with the ridge line of the protrusion 9 in the tire, which is advantageous in preventing poor appearance.

[0036] The slit 31 may be provided directly in the mold 10 (side plate 11), but as shown in FIG. 7, the mold 10 may be structured to include a mold body 10A and a replacement piece 10B in which the slit 31 is formed, and may be provided with a fixing hole for fitting the replacement piece 10B to the mold body 10A. The replacement piece 10B is a part that is detachably inserted into a fixing hole provided in the mold body 10A, and the molding surface of the mold 10 is formed by fitting the replacement piece 10B to the fixing hole. Note that FIG. 7 shows a state in which the replacement piece 10B is fitted into the fixing hole of the mold body 10A. In this specification, the slit 31 can be provided at any position of the replacement piece 10B, but it is preferable to form the slit 31 by making the surface of the replacement piece 10B that abuts against the side of the fixing hole recess against the side of the fixing hole that abuts against when fitted, as in the example shown in the figure. With this configuration, cleaning inside the slit 31 becomes easier when cleaning the mold 10 after vulcanization, and productivity can be improved.

[0037] The slit 31 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 mold 10 or using the replacement piece 10B as described above.

[0038] When a tire is manufactured using the above-mentioned tire molding die, a tire can be manufactured by a general method, that is, by molding an unvulcanized tire and vulcanizing the unvulcanized tire in the above-mentioned tire molding die. The tire manufactured in this way (the tire of the present invention) has a plurality of protrusions 9 having a longitudinal direction on the surface of the tire side portion (sidewall portion 2). At this time, air is removed from the recessed portion 30 when the protrusions 9 are molded by the above-mentioned slits 31, and since the slits 31 are fine gaps, almost no rubber flows into them, so in the tire of the present invention, basically no traces due to air removal are formed on the surface of the protrusions 9. Even if traces of the slits 31 are formed due to the rubber that has flowed into the slits 31, only fine linear traces remain on some of the protrusions 9. In other words, the tire of the present invention has traces of the slits 31 for air removal on the surface of less than half of the plurality of protrusions 9. Even if traces of the slits 31 are formed, as described above, the traces of the slits 31 are linear traces of very small width, so that the shape of the convex portions 9 is not marred by the traces of the slits 31, and the air resistance reduction performance of the convex portions 9 can be satisfactorily exhibited.

[0039] The present invention will be further described below with reference to examples, but the scope of the present invention is not limited to these examples. EXAMPLES

[0040] In manufacturing tires having a tire size of 165 / 50R16 75V and the structure illustrated in Figs. 1 and 2, the tire molding dies were varied in the following manner as shown in Table 1: the method of exhausting air from within the recesses, the direction of the slits, the arrangement of the slits / vent holes, the width of the slits / vent holes, the length of the slits / vent holes, the opening area of ​​the slits / vent holes, and the method of forming the slits / vent holes (Conventional Example 1, Comparative Example 1, Examples 1 to 7).

[0041] In Table 1, the column "Exhaust method" indicates whether a vent hole or a slit was used as an exhaust hole for exhausting the air in the recess. The column "Slit direction" indicates whether the slit extends along the longitudinal direction or the lateral direction of the recess (the opening end of the vent hole is circular, so the extending direction is not defined). The column "Layout of slit / vent hole" indicates the layout position of the slit or vent hole in the recess. The column "Slit / vent hole width" indicates the width of the slit or vent hole. The width of the vent hole is essentially the diameter of the vent hole. The column "Slit / vent hole length" indicates the length of the slit or vent hole. The length of the vent hole is also essentially the diameter of the vent hole. In this column, the ratio to the length of the recess is also indicated. The column "Slit / vent hole formation method" indicates "direct formation" when the slit or vent hole is directly provided in the mold, and "replacement piece" when a replacement piece with a slit or vent hole formed therein is used. Incidentally, since Conventional Example 1 is an example in which no vent holes or slits are provided (no exhaust mechanism is provided in the recess), no numerical values ​​are shown for each item in the table.

[0042] These pneumatic tires were evaluated for appearance defects, air resistance, and workability using the following evaluation methods. The results are shown in Table 1.

[0043] Prevents appearance defects 100 tires were vulcanized using each tire molding mold, and the number of tires that had visual defects (poor aesthetics due to improper shaping) on ​​the protruding parts of the tires obtained was counted to 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 being set at 100. A higher index value means better prevention of visual defects.

[0044] Low air resistance The test tires manufactured using each tire molding die were mounted on wheels with a rim size of 16 x 4.5J, the tire internal pressure was set to 230kPa, and the tires were mounted on a test vehicle. In accordance with JIS D1012, the vehicle speed while coasting was measured and the running resistance was calculated using the multipoint regression method. The evaluation results were expressed as an index with the value of Conventional Example 1 being 100. The higher the index value, the lower the air resistance, meaning that the tire is more excellent in low air resistance.

[0045] Workability The time required to clean the mold (exhaust mechanism) after vulcanizing a tire using each tire molding mold was measured. The evaluation results were expressed as an index using the reciprocal of the measured value, with the value of Comparative Example 1 being 100. The larger the index value, the shorter the time required to clean the mold and the better the workability. Note that, as mentioned above, Conventional Example 1 does not have an exhaust mechanism in the recess, so workability tests were not conducted.

[0046] [Table 1]

[0047] As is clear from Table 1, the tires of Examples 1 to 7 reduced air resistance while preventing poor appearance compared to Conventional Example 1, and also exhibited good workability equal to or better than that of Comparative Example 1. On the other hand, Comparative Example 1 prevented poor appearance compared to Conventional Example 1 because exhaust was performed through the vent holes, but did not achieve the effect of improving low air resistance because traces (cut marks) of cutting off the spews caused by the vent holes were present on the surface of the convex portions (fins).

[0048] The present disclosure includes the following inventions. Invention [1] A tire molding die for molding a tire having a plurality of longitudinally extending protrusions on the surface of a tire side portion, the protrusions being arranged at intervals in the tire circumferential direction, A tire molding die comprising: a recess for forming the protrusion; and an air vent slit formed so as to open on an inner surface of the recess. Invention [2] The tire molding mold according to invention [1], wherein the slit extends along the longitudinal direction of the recess. Invention [3] A tire molding mold according to invention [1] or [2], characterized in that the slit is arranged in a portion where the depth of the recess is greatest. Invention [4] The tire molding mold according to any one of inventions [1] to [3], wherein the width of the slit is 0.01 mm to 0.5 mm. Invention [5] The tire molding mold according to any one of inventions [1] to [4], wherein the length of the slit is 2% to 100% of the length of the recess. Invention [6] The tire molding mold according to any one of inventions [1] to [5], wherein the opening area of ​​the slit is 0.01% to 15% of the opening area of ​​the recess. Invention [7] A tire molding mold according to any one of inventions [1] to [6], comprising a replacement piece having the slit formed therein, and a fixing hole into which the replacement piece fits. Invention [8] A method for manufacturing a tire using a tire molding mold according to any one of Inventions [1] to [7], comprising molding an unvulcanized tire and vulcanizing the tire in the tire molding mold. Invention [9] A tire having a plurality of longitudinal convex portions on the surface of the tire side portion that are spaced apart in the circumferential direction of the tire, wherein less than half of the plurality of convex portions have traces of air vent slits on their surfaces. [Explanation of symbols]

[0049] 1 Tread section 2 Sidewall 3 Bead section 4 Carcass layer 5 Bead Core 6 Bead Filler 7 Belt layer 8 Belt reinforcement layer 9 Fin 10. Mold 11 Side plate 12 Bead ring 13 Sectors 20 Bladder 30 Recess 31 Slit CL Tire Equator

Claims

1. A tire molding die for molding a tire having a plurality of longitudinally extending protrusions arranged at intervals in the tire circumferential direction on a surface of a tire side portion, A tire molding die comprising: a recess for forming the protrusion; and an air vent slit formed so as to open on an inner surface of the recess.

2. 2. The tire mold according to claim 1, wherein the slit extends along the longitudinal direction of the recess.

3. 3. The tire molding mold according to claim 1, wherein the slit is disposed at a position where the depth of the recess is greatest.

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

5. 3. The tire molding mold according to claim 1, wherein a length of the slit is 2% to 100% of a length of the recess.

6. 3. The tire molding mold according to claim 1, wherein an opening area of ​​the slit is 0.01% to 15% of an opening area of ​​the recess.

7. 3. The tire molding die according to claim 1, further comprising a replacement piece having the slit formed therein, and a fixing hole into which the replacement piece is fitted.

8. 3. A method for manufacturing a tire using the tire molding mold according to claim 1 or 2, comprising molding an unvulcanized tire and vulcanizing the tire in the tire molding mold.

9. A tire having a plurality of longitudinally extending protrusions on the surface of a tire side portion, the plurality of protrusions being spaced apart in the tire circumferential direction, the tire being characterized in that less than half of the plurality of protrusions have traces of air vent slits on their surfaces.

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