Vulcanizing mold for pneumatic tire and pneumatic tire

Abstract

To provide a technology for improving the releasability of pneumatic tires.SOLUTION: A mold has an upper side mold 1 having a first molding surface 11 that forms the upper sidewall of the pneumatic tire during vulcanization, and an upper bead ring 2 having a molding surface 20 that forms the upper bead of the pneumatic tire during vulcanization. The molding surface 20 of the upper bead ring 2 includes a second molding surface 21 extending from the tire radial direction inner side RD2 end in the molding surface 20 of the upper bead ring 2 to the tire radial direction outer side RD1. The surface roughness of the second molding surface 21 is smoother than the surface roughness of the first molding surface 11.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a vulcanizing mold for a pneumatic tire and a pneumatic tire. [Background technology]

[0002] For example, Patent Document 1 discloses a tire vulcanizer for manufacturing a vulcanized pneumatic tire by vulcanizing a green tire in a vulcanization mold. The vulcanization mold vulcanizes the green tire with the tire axis aligned vertically. For this reason, the vulcanization mold has an upper side mold that forms the upper sidewall of the tire, an upper bead ring that forms the upper bead of the tire, a lower side mold that forms the lower sidewall of the tire, a lower bead ring that forms the lower bead of the tire, and a sector that forms the tread of the tire. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-361631 A Summary of the Invention [Problem to be solved by the invention]

[0004] When vulcanization of a pneumatic tire is completed and the vulcanization mold is opened, a phenomenon may occur in which the vulcanized tire adheres to the upper side mold and the upper bead ring, as shown in Fig. 4. If an attempt is made to hold a tire that is adhered to the upper side mold and the upper bead ring and transport it outside the mold, the tire held by the holding part of the transport mechanism may deform, resulting in a defective tire. In particular, in the case of a vulcanizer shown in Patent Document 1 that has a claw-shaped holding part that holds the upper bead of the tire when the mold is opened after vulcanization, the vulcanized tire remains stuck to the mold, and the above-mentioned problem is likely to occur.

[0005] The present disclosure provides a technique for improving the demoldability of a pneumatic tire. [Means for solving the problem]

[0006] The vulcanization mold for a pneumatic tire disclosed herein comprises an upper side mold having a first molding surface that forms the upper sidewall of the pneumatic tire during vulcanization, and an upper bead ring having a molding surface that forms the upper bead of the pneumatic tire during vulcanization, the molding surface of the upper bead ring including a second molding surface extending from an inner end of the molding surface of the upper bead ring toward an outer end in the tire radial direction, and the surface roughness of the second molding surface is smoother than the surface roughness of the first molding surface. [Brief description of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view showing a vulcanization mold for a pneumatic tire T according to a first embodiment. [Diagram 2] FIG. 2 is an enlarged view showing the upper side mold 1 and the upper bead ring 2. [Diagram 3] 4 is an enlarged view showing the lower side mold 3 and the lower bead ring 4. FIG. [Figure 4] 1 is a cross-sectional view showing a state in which a pneumatic tire T is fixed to an upper side mold 1 and an upper bead ring 2 when the vulcanization mold is opened. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A first embodiment of the present disclosure will be described below with reference to the drawings. Fig. 1 is a cross-sectional view showing a vulcanization mold for a pneumatic tire according to the first embodiment. Fig. 2 is an enlarged view showing an upper side mold 1 and an upper bead ring 2. Fig. 3 is an enlarged view showing a lower side mold 3 and a lower bead ring 4. Fig. 4 is a cross-sectional view showing a state in which a pneumatic tire T is fixed to the upper side mold 1 and the upper bead ring 2 when the vulcanization mold is opened.

[0009] As shown in FIG. 1, the vulcanizing mold molds the outer surface of the pneumatic tire T. The vulcanizing mold has an upper side mold 1 and a lower side mold 3 that are paired vertically, an upper bead ring 2 and a lower bead ring 4 that are paired vertically, and a plurality of sectors 5 arranged in the tire circumferential direction. The sectors 5 are molds for molding the tread surface T1 of the pneumatic tire T. The plurality of sectors 5 are displaceable in the tire radial direction RD, and move to the tire radial outer side RD1 when the mold opens. The upper side mold 1 and the upper bead ring 2 are configured to be movable in the up-down direction (AD) relative to the lower side mold 3 and the lower bead ring 4, and move upward (AD1) when the mold opens. The up-down direction (AD) coincides with the tire axial direction AD. The upper side is the first side AD1 in the tire axial direction AD, and the other side is the second side AD2 in the tire axial direction AD.

[0010] 1, the bladder 6 is diagrammatically shown by a dashed line. The bladder 6 is configured to include a toroidal rubber elastic body that can expand and contract, and is disposed on the inner surface side of the pneumatic tire T. The bladder 6 is inflated by the supply of pressurized gas to pressurize the pneumatic tire T from the inside.

[0011] As shown in Figs. 1 and 2, the upper side mold 1 has a molding surface 10 that forms the upper sidewall T2 of the pneumatic tire T. The molding surface 10 that forms the upper sidewall T2 includes a first molding surface 11 that forms a reference surface along the tire profile. The molding surface 10 that forms the sidewall T2 may include not only the first molding surface 11 but also an uneven surface that forms an uneven shape as a tire design and an uneven surface that forms a mark (letters, figures). The profile (reference surface) is disposed at a position that is rotationally symmetrical about the tire rotation axis. A portion of the profile (reference surface) extends continuously around the entire circumference in the tire circumferential direction.

[0012] The upper bead ring 2 has a molding surface 20 that forms an upper bead T3 of the pneumatic tire T. The molding surface 20 that forms the upper bead T3 includes an end (P1) that forms the toe of the bead T3 (a corner portion on the radially inner side RD2 of the tire and the axially inner side of the tire) and a single curved surface P2 that forms the heel of the bead T3 (a corner portion from the toe toward the axially outer side of the tire).

[0013] 1 and 3, the lower side mold 3 has a molding surface 30 that forms the lower sidewall T2 of the pneumatic tire T. The molding surface 30 that forms the lower sidewall T2 includes a third molding surface 31 that forms a reference surface along the profile of the tire. In addition, the molding surface 30 that forms the sidewall T2 may include not only the third molding surface 31 but also an uneven surface that forms an uneven shape as a tire design and an uneven surface that forms a mark (letters, figures).

[0014] The lower bead ring 4 has a molding surface 40 that forms a lower bead T3 of the pneumatic tire T. The molding surface 40 that forms the lower bead T3 includes an end (P1) that forms the toe of the bead T3 (a corner portion on the inner side RD2 in the tire radial direction and the inner side in the tire axial direction) and a single curved surface P2 that forms the heel of the bead T3 (a corner portion from the toe toward the outer side in the tire axial direction).

[0015] As shown in Fig. 4, the upper side mold 1 and the upper bead ring 2 move together when the mold opens after vulcanization is completed. The molding surface 10 of the upper side mold 1 and the molding surface 20 of the upper bead ring 2 are always connected to each other. As shown in Fig. 4, the sidewall T2 and the bead T3 of the vulcanized tire T tend to adhere to the connected molding surfaces 10, 20.

[0016] Therefore, the present disclosure employs the following means. The bead T3 adhered to the molding surface is less likely to separate from the mold than the sidewall T2 adhered to the molding surface. This is because the weight of the pneumatic tire T is more likely to be applied to the sidewall T2 close to the tread, and the bead T3 has high rigidity and is less likely to deform because it includes a bead core. In order to improve the mold releasability of the bead T3, the surface roughness of the second molding surface 21 of the upper bead ring 2 is made smoother than the surface roughness of the molding surface 10 forming the sidewall T2. The second molding surface 21 includes a surface extending from the end (P1) of the inner side RD2 in the tire radial direction of the molding surface 20 of the upper bead ring 2 toward the outer side RD1 in the tire radial direction. The second molding surface 21 can be said to be the end of the inner side RD2 in the tire radial direction that forms the bead T3 among the molding surfaces 10 and 20. In cases where the surface roughness of the molding surface 10 forming the sidewall T2 is not uniform, such as when the surface roughness of the first molding surface 11, the surface roughness of the uneven surface forming the uneven shape as the tire design, and the surface roughness of the uneven surface forming the mark (letters, figures) are different, it is preferable to use the first molding surface 11 as a representative of the molding surface 10. The first molding surface 11 forms a reference surface for a relatively wide range of the sidewall T2. In other words, it is preferable that the surface roughness of the second molding surface 21 is smoother than the surface roughness of the first molding surface 11.

[0017] The arithmetic mean roughness Ra of the molding surface 10 (first molding surface 11) forming the sidewall T2 is preferably 1.5 μm or more and 1.9 μm or less. The calculated mean roughness Ra of the second molding surface 21 is preferably 0.1 μm or more and less than 1.5 μm. Furthermore, the calculated mean roughness Ra of the second molding surface 21 is preferably 1.0 μm or more and 1.4 μm or less. The smaller the value of the arithmetic mean roughness Ra, the more improved the releasability of the pneumatic tire T, but on the other hand, the tire surface may become smooth and glossy, which may deteriorate the aesthetic appearance. By keeping the minimum value of the arithmetic mean roughness Ra of the second molding surface 21 at 1.0 μm, it is possible to suppress deterioration of the aesthetic appearance. By setting the maximum value of the arithmetic mean roughness Ra of the second molding surface 21 to 1.4 μm, a difference from the minimum value of the arithmetic mean roughness Ra of the first molding surface 11, 1.5 μm, can be secured, making it possible to more easily achieve the effect of improving the releasability of the pneumatic tire T.

[0018] The second molding surface 21, which has a smooth surface roughness, may extend from the part P1 that forms the toe (the end of the molding surface 20 on the inner side RD2 in the tire radial direction) to the outer side RD1 in the tire radial direction, but preferably includes a surface up to the curved surface P2 that forms the heel. This is because the surface of the molding surface 20 that extends from the toe to the heel is inclined from the inner side in the tire axial direction AD to the outer side in the tire axial direction AD, and therefore is likely to trigger demolding of the pneumatic tire T.

[0019] In the first embodiment, the second molding surface 21 having a smooth surface roughness is set on the entire molding surface 20 of the upper bead ring 2. That is, the entire molding surface 20 of the upper bead ring 2 (second molding surface 21) is smoother than the first molding surface 11 of the upper side mold 1. By making the entire molding surface 20 of the upper bead ring 2 the second molding surface 21, it is only necessary to control the surface roughness for each component of the upper side mold 1 and the upper bead ring 2, and workability can be improved.

[0020] The surface roughness of the molding surface 10 (first molding surface 11) of the upper side mold 1 is set to the above surface roughness by a blasting treatment in which a spraying material such as glass or resin is sprayed onto the molding surface 10 (first molding surface 11). The second molding surface 21 of the upper bead ring 2 is set to the above surface roughness by forming a plating layer of hard chrome or the like after blasting, by forming a plating layer without blasting, by polishing, etc. When cleaning a mold, a blasting treatment is often performed, and by forming a plating layer, the wear resistance of the mold against the blasting treatment is improved, making it easier to maintain the above surface roughness relationship.

[0021] Although this has less adverse effects than adhesion of the vulcanized tire T to the upper side mold 1 and the upper bead ring 2, there are cases in which the vulcanized tire T also adheres to the lower side mold 3 and the lower bead ring 4 when the molds are opened. In order to also deal with adhesion of the tire T to the lower side mold 3 and the lower bead ring 4, it is preferable to set the surface roughness in the same manner as for the upper side mold 1 and the upper bead ring 2.

[0022] Specifically, the surface roughness of the fourth molding surface 41 of the lower bead ring 4 is made smoother than the surface roughness of the molding surface 30 forming the sidewall T2. The fourth molding surface 41 includes a surface from the end (P1) of the molding surface 40 of the lower bead ring 4 on the inner side RD2 in the tire radial direction toward the outer side RD1 in the tire radial direction. The fourth molding surface 41 can be said to be the end of the inner side RD2 in the tire radial direction that forms the bead T3 among the molding surfaces 30, 40. When the surface roughness of the molding surface 30 forming the sidewall T2 is not uniform, such as when the surface roughness of the third molding surface 31, the surface roughness of the uneven surface that forms the uneven shape as the tire design, and the surface roughness of the uneven surface that forms the mark (characters, figures) are different, it is preferable to use the third molding surface 31 as a representative of the molding surface 30. The third molding surface 31 is for forming a reference surface of a relatively wide range of the sidewall T2. In other words, it is preferable that the surface roughness of the fourth molding surface 41 is smoother than the surface roughness of the third molding surface 31.

[0023] The surface roughness (arithmetic mean roughness Ra) of the molding surface 30 (third molding surface 31) forming the sidewall T2 is preferably 1.5 μm or more and 1.9 μm or less. The calculated mean roughness Ra of the fourth molding surface 41 is preferably 0.1 μm or more and less than 1.5 μm. Furthermore, the calculated mean roughness Ra of the fourth molding surface 41 is preferably 1.0 μm or more and 1.4 μm or less. Similar to the surface roughness of the second molding surface 21 of the upper bead ring 2, the surface roughness of the fourth molding surface 41 of the lower bead ring 4 is made smoother than that of the upper side mold 1 and the lower side mold 3, thereby achieving aesthetic uniformity on both side surfaces of the tire T.

[0024] The pneumatic tire T vulcanized using the above mold has a pair of sidewalls T2 on a first side AD1 (upper) in the tire axial direction AD, and a pair of beads T3 on the first side AD1 (upper) in the tire axial direction AD. The surface roughness of the second outer surface of the upper bead T3 corresponding to the second molding surface 21 is smoother than the surface roughness of the first outer surface of the upper sidewall T2 corresponding to the first molding surface 11. In addition, the surface roughness of the fourth outer surface of the lower (second side AD2) bead T3 corresponding to the fourth molding surface 41 is smoother than the surface roughness of the third outer surface of the lower (second side AD2) sidewall T2 corresponding to the third molding surface 31.

[0025] <Examples 1 to 3 and Comparative Example 1> In order to show the effects, examples 1 to 3 and comparative example 1 will be described below.

[0026] Comparative Example 1 A blasting treatment was performed by spraying glass material. The arithmetic mean roughness Ra of the molding surfaces of the upper side mold 1, the upper bead ring 2, the lower side mold 3, and the lower bead ring 4 was set to 1.5 μm or more and 1.7 μm or less, and there was no difference in surface roughness.

[0027] Example 1 A blasting treatment was performed by spraying a glass material onto the upper side mold 1 and the lower side mold 3. The arithmetic mean roughness Ra of the first molding surface 11 and the third molding surface 31 was set to 1.5 μm or more and 1.7 μm or less. A hard chrome plating layer after the blasting treatment was formed on the second molding surface 21 and the fourth molding surface 41. The arithmetic mean roughness Ra of the second molding surface 21 and the fourth molding surface 41 was 1.3 μm.

[0028] Example 2 A hard chrome plating layer was formed after blasting on the second molding surface 21 and the fourth molding surface 41. The arithmetic mean roughness Ra of the second molding surface 21 and the fourth molding surface 41 was 0.2 μm. The rest was the same as in Example 1.

[0029] Example 3 A hard chrome plating layer was formed on the second molding surface 21 and the fourth molding surface 41 without blasting. The arithmetic mean roughness Ra of the second molding surface 21 and the fourth molding surface 41 was 0.1 μm. The rest was the same as in Example 1.

[0030] In Comparative Example 1, after tires were manufactured using a certain mold for one month, a tire deformation defect occurred due to the vulcanized tire T sticking to the upper side mold 1 and the upper bead ring 2. On the other hand, after the mold used in Comparative Example 1 was treated to produce Example 1, tires were manufactured for one month, and no tire deformation defects occurred due to the vulcanized tire T adhering to the upper side mold 1 and the upper bead ring 2. The number of tires manufactured in Example 1 was about seven times that of Comparative Example 1. After the mold used in Comparative Example 1 was treated to produce Example 2, tires were manufactured for one month, and no tire deformation defects occurred due to the vulcanized tire T adhering to the upper side mold 1 and the upper bead ring 2. The number of tires manufactured in Example 2 was about seven times that of Comparative Example 1. After the mold used in Comparative Example 1 was treated to produce Example 3, tires were manufactured for one month, and no tire deformation defects occurred due to the vulcanized tire T adhering to the upper side mold 1 and the upper bead ring 2. The number of tires manufactured in Example 3 was about seven times that of Comparative Example 1. Therefore, it can be understood that the releasability of the pneumatic tire T is improved in Examples 1 to 3 compared to Comparative Example 1.

[0031] [Variations] (A) In the above embodiment, the surface roughness of the fourth molding surface 41 is smoother than that of the third molding surface 31, but this is not limited to the above as long as the surface roughness of the second molding surface 21 is smoother than that of the first molding surface 11. The surface roughness of the fourth molding surface 41 and the surface roughness of the third molding surface 31 may be the same.

[0032] (B) In the above embodiment, the second molding surface 21 is formed with a plated layer, but is not limited to this.

[0033] (C) In the above embodiment, the arithmetic mean roughness Ra of the second molding surface 21 is preferably 0.1 μm or more and less than 1.5 μm, but is not limited thereto. For example, the arithmetic mean roughness Ra of the second molding surface 21 may be 0.1 μm or more and 1.4 μm or less, 1.0 μm or more and less than 1.5 μm, or 0.1 μm or more and 1.0 μm or less.

[0034] [1] As described above, the vulcanization mold for the pneumatic tire of the first embodiment includes an upper side mold 1 having a first molding surface 11 that forms the upper sidewall T2 of the pneumatic tire T during vulcanization, and an upper bead ring 2 having a molding surface 20 that forms the upper bead T3 of the pneumatic tire T during vulcanization, and the molding surface 20 of the upper bead ring 2 includes a second molding surface 21 that extends from the end of the molding surface 20 of the upper bead ring 2 on the inner side RD2 in the tire radial direction toward the outer side RD1 in the tire radial direction, and the surface roughness of the second molding surface 21 may be smoother than the surface roughness of the first molding surface 11. When the mold is opened after vulcanization, the vulcanized pneumatic tire T tends to stick to the molding surfaces 10, 20 of the upper side mold 1 and the upper bead ring 2. By making the surface roughness of the second molding surface 21 located at the end of the inner side RD2 in the tire radial direction of the molding surface 20 of the upper bead ring 2 smoother than the surface roughness of the molding surface 10 of the upper side mold 1, it becomes possible to easily release the pneumatic tire T stuck to the molding surfaces 10, 20 of the upper side mold 1 and the upper bead ring 2 from the end of the inner side RD2 in the tire radial direction as a starting point.

[0035] [2] In the vulcanization mold for a pneumatic tire described in [1] above, the second molding surface 21 may include a surface from a portion P1 that forms the toe of the bead T3 of the pneumatic tire T to a curved surface P2 that forms the heel of the bead T3 of the pneumatic tire T. The surface from the portion P1 forming the toe of the bead T3 to the curved surface P2 forming the heel is located on the innermost side RD2 in the tire radial direction of the pneumatic tire T that is attached to the upper side mold 1 and the upper bead ring 2, and therefore by smoothing the surface roughness of the surface from the portion P1 forming the toe of the bead T3 to the curved surface P2 forming the heel, it is possible to accurately improve the releasability of the pneumatic tire T. In addition, since this surface is a portion that is hidden when the rim is attached, there is little impact even if the appearance is deteriorated by smoothing it.

[0036] [3] In the vulcanizing mold for a pneumatic tire according to the above [1] or [2], the second molding surface 21 may include the entire molding surface 20 of the upper bead ring 2. Changing the surface roughness of the entire molding surface 20 of the upper bead ring 2 can improve workability more than changing the surface roughness of a portion of the molding surface 20 of the upper bead ring 2.

[0037] [4] In the vulcanizing mold for a pneumatic tire described in any one of [1] to [3] above, the arithmetic mean roughness Ra of the second molding surface 21 may be 0.1 μm or more and less than 1.5 μm, and the arithmetic mean roughness Ra of the first molding surface 11 may be 1.5 μm or more and 1.9 μm or less. This is a desirable surface roughness.

[0038] [5] In the vulcanizing mold for a pneumatic tire described in the above item [4], the second molding surface 21 may have an arithmetic mean roughness Ra of 1.0 μm or more and 1.4 μm or less. This makes it possible to prevent deterioration of the appearance of the outer surface of the tire corresponding to the second molding surface 21.

[0039] [6] In the vulcanizing mold for a pneumatic tire according to any one of the above items [1] to [5], a plating layer may be formed on the second molding surface 21. When cleaning a mold, a blasting treatment is often performed, and the plating layer improves the wear resistance of the mold against the blasting treatment, making it easier to maintain the above-mentioned surface roughness relationship, and making it easier to maintain the releasability of the pneumatic tire T.

[0040] [7] A vulcanization mold for a pneumatic tire as described in any one of [1] to [6] above may include a lower side mold 3 having a third molding surface 31 that forms a lower sidewall T2 of the pneumatic tire T during vulcanization, and a lower bead ring 4 having a molding surface 40 that forms a lower bead T3 of the pneumatic tire T during vulcanization, wherein the molding surface 40 of the lower bead ring 4 includes a fourth molding surface 41 extending from an end (P1) of the molding surface 40 of the lower bead ring 4 on the inner side RD2 in the tire radial direction toward the outer side RD1 in the tire radial direction, and the surface roughness of the fourth molding surface 41 is smoother than the surface roughness of the third molding surface 31. According to this configuration, the releasability of the pneumatic tire T is improved, and the aesthetic appearance of the beads T3 on both sides of the tire in the tire axial direction AD can be unified.

[0041] [8] As in the first embodiment, the pneumatic tire T may include a pair of beads T3 and a pair of sidewalls T2 extending from the pair of beads T3 to the tire radial outside RD1, wherein the sidewall T2 on a first side AD1 in the tire axial direction AD of the pair of sidewalls T2 has a first outer surface, and the bead T3 on the first side AD1 of the pair of beads T3 has a second outer surface extending from the toe toward the tire radial outside RD1, and the surface roughness of the second outer surface may be smoother than the surface roughness of the first outer surface. According to this configuration, the releasability of the pneumatic tire T from the mold is improved, so that it is possible to provide a tire that is close to the designed shape and has tire performance values ​​that are close to the designed tire shape.

[0042] Although the embodiments of the present disclosure have been described above based on the drawings, the specific configurations should not be considered to be limited to these embodiments. The scope of the present disclosure is indicated not only by the description of the above-mentioned embodiments but also by the claims, and further includes all modifications within the meaning and scope equivalent to the claims.

[0043] The structures employed in the above-described embodiments may be employed in any other embodiment. The specific configurations of the components are not limited to the above-described embodiments, and may be modified in various ways without departing from the spirit of the present disclosure.

[0044] For example, the order of execution of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings, can be arbitrary, as long as the output of a previous process is not used in a subsequent process. Even if the flow in the claims, specifications, and drawings is described using "first," "next," and the like for convenience, this does not mean that it is essential to execute the processes in this order. [Explanation of symbols]

[0045] 1: Upper side mold 2: Upper bead ring 3: Lower side mold 4: Lower bead ring 10, 20, 30, 40: Molding surface 11: 1st molding surface 21:Second molding surface 31: 3rd molding surface 41: 4th molding surface AD: Tire axial direction AD1: First side RD: Tire radial direction RD1: Tire radial outer side RD2: Tire radial inner side T: Pneumatic tire T2: Sidewall T3: Bead

Claims

1. an upper side mold having a first molding surface that forms an upper sidewall of a pneumatic tire during vulcanization; and an upper bead ring having a molding surface that forms an upper bead of the pneumatic tire during vulcanization, the molding surface of the upper bead ring includes a second molding surface extending from an end of the molding surface of the upper bead ring that is on an inner side in the tire radial direction toward an outer side in the tire radial direction, A pneumatic tire vulcanization mold, wherein the second molding surface has a surface roughness that is smoother than the surface roughness of the first molding surface.

2. 2. The pneumatic tire vulcanization mold according to claim 1, wherein the second molding surface includes a surface extending from a portion that forms a toe of a bead of the pneumatic tire to a curved surface that forms a heel of the bead of the pneumatic tire.

3. The pneumatic tire vulcanization mold according to claim 1 , wherein the second molding surface includes an entire molding surface of the upper bead ring.

4. 2. The pneumatic tire vulcanization mold according to claim 1, wherein the second molding surface has an arithmetic mean roughness Ra of 0.1 μm or more and less than 1.5 μm, and the first molding surface has an arithmetic mean roughness Ra of 1.5 μm or more and 1.9 μm or less.

5. The vulcanizing mold for a pneumatic tire according to claim 4 , wherein the second molding surface has an arithmetic mean roughness Ra of 1.0 μm or more and 1.4 μm or less.

6. The pneumatic tire vulcanizing mold according to any one of claims 1 to 5, wherein a plating layer is formed on the second molding surface.

7. a lower side mold having a third molding surface that forms a lower sidewall of the pneumatic tire during vulcanization; and a lower bead ring having a molding surface that forms a lower bead of the pneumatic tire during vulcanization, the molding surface of the lower bead ring includes a fourth molding surface extending from an inner end of the molding surface of the lower bead ring toward an outer end in the tire radial direction, The pneumatic tire vulcanization mold according to claim 1 , wherein a surface roughness of the fourth molding surface is smoother than a surface roughness of the third molding surface.

8. A pair of beads and a pair of sidewalls extending radially outward from the pair of beads, The sidewall on a first side in the tire axial direction of the pair of sidewalls has a first outer surface, The first bead of the pair of beads has a second outer surface extending from a toe toward an outer side in a tire radial direction, The second outer surface has a surface roughness smoother than a surface roughness of the first outer surface.

Images