Tire and tire mold

Abstract

The invention provides a tire and a tire mold, which can emphasize the light and dark visual effect based on sawteeth, thereby exhibiting excellent visibility. In a tire having a stamp part (21) and a background part (22) surrounding the stamp part (21) in a side wall part (2), and a saw tooth (10) including a plurality of ridges (11) arranged in parallel is formed in either the stamp part (21) or the background part (22), each ridge (11) has, in a cross-section orthogonal to the longitudinal direction of the ridge (11), a side wall surface (13) that forms a negative gradient with respect to a normal (L) of a reference surface (B) that forms the ridge (11); and an inclined surface (14) that is inclined with respect to the reference surface (B).

Description

Technical Field

[0001] The present invention relates to a tire having serrations formed on its sidewall and a tire mold for molding the same, and more particularly to a tire and a tire mold capable of emphasizing the light and dark visual effects of the serrations, thereby exhibiting excellent visibility. Background Art

[0002] A tire has been proposed in the industry, wherein a logo portion comprising text, graphics, symbols, etc. and a background portion surrounding the logo portion are formed on the sidewall of the tire, and serrations comprising a plurality of ridges arranged in parallel are formed on either the logo portion or the background portion (see, for example, Patent Documents 1 to 3). When such serrations are provided on the sidewall, the light and dark visual effects created by the serrations can improve the visibility of the logo portion.

[0003] However, when emphasizing the light and dark visual effect, it is best to form the ridges higher, but the height of the ridges is limited in the sidewall of the tire. Therefore, the effect of improving visibility based on the ridge height is limited.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2003-175707

[0007] Patent Document 2: Japanese Patent Application Publication No. 2019-147495

[0008] Patent Document 3: Japanese Patent Application Laid-Open No. 2020-6863 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] An object of the present invention is to provide a tire and a tire mold that can emphasize the light and dark visual effect of serrations and thus exhibit excellent visibility.

[0011] Means used to solve problems

[0012] The tire of the present invention for achieving the above-mentioned object is a tire having a logo portion and a background portion surrounding the logo portion on a sidewall portion, wherein a serration portion including a plurality of ridges arranged in parallel is formed in either the logo portion or the background portion, and is characterized in that:

[0013] Each ridge has, in a cross section perpendicular to the longitudinal direction of the ridge, a side wall surface having a negative gradient relative to a normal line of a reference plane forming the ridge, and an inclined surface inclined relative to the reference plane.

[0014] In addition, the tire mold of the present invention for achieving the above object is a tire mold for molding the above tire, and is characterized in that it has a molding surface having a shape corresponding to the emblem portion, the background portion, and the serrations.

[0015] Advantages of the Invention

[0016] In the present invention, each ridge has a side wall surface with a negative gradient with respect to the normal of the reference plane, whereby it is easy to form a shadow along the ridge, and light is effectively absorbed between the ridges. In addition, each ridge has an inclined surface inclined with respect to the reference plane, whereby the inclined surface effectively reflects light. Therefore, according to the above ridge structure, it is possible to emphasize the light and dark visual effect based on the serrations while suppressing the ridge height to be low, thereby exhibiting excellent visibility.

[0017] In the present invention, each ridge preferably has a polygonal shape in a cross section orthogonal to the length direction of the ridge. In this way, when the cross-sectional shape of the ridge is a polygon, the reflection direction of light changes according to its cross-sectional shape, whereby the light and dark visual effect can be made to vary. In particular, when the cross-sectional shape of the ridge is a triangle, the light and dark visual effect can be emphasized.

[0018] The angle α of the side wall surface with respect to the normal of the reference plane is preferably in the range of -20° ≤ α < 0°. By setting the angle α of the side wall surface within the above range, the light and dark visual effect can be improved.

[0019] The vertex angle β of the ridge in a cross section orthogonal to the length direction of the ridge is preferably in the range of 30° ≤ β ≤ 60°. By setting the vertex angle of the ridge within the above range, the light and dark visual effect can be improved.

[0020] The pitch of the ridges is preferably in the range of 0.5 mm to 1.2 mm, and the height of the ridges is preferably in the range of 0.2 mm to 0.5 mm. Since the ridges having the above-described cross-sectional shape have excellent visibility, the pitch of the ridges can be increased and the height of the ridges can be decreased. Therefore, the number of ridges can also be reduced, and the machining workability of the tire mold can be improved.

[0021] The ridge preferably has a chamfered portion formed of a flat surface or a curved surface between the side wall surface and the inclined surface. In the case where such a chamfered portion is provided, the light and dark visual effect can be made to vary by changing the absorption or reflection direction of light.

[0022] The tire of the present invention can be a pneumatic tire or a non-pneumatic tire. When it is a pneumatic tire, it can be filled with an inert gas such as air or nitrogen or other gases inside. The non-pneumatic tire includes a solid tire. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1This is a meridian cross-section view of a pneumatic tire configured according to an embodiment of the present invention.

[0024] Figure 2 This is a plan view showing a logo portion, a background portion, and serrations formed in the logo portion, which are formed in a sidewall portion.

[0025] Figure 3 This is Figure 2 a cross-section view taken along the arrow III-III.

[0026] Figure 4 This is a cross-section view after adding dimension lines to Figure 3 it.

[0027] Figure 5 This is a plan view showing a logo portion, a background portion, and serrations formed in the background portion, which are formed in a sidewall portion.

[0028] Figure 6 This is a cross-section view showing an example of the light reflection state in a sidewall portion.

[0029] Figure 7 This is a cross-section view showing a modified example of serrations.

[0030] Figure 8 This is a cross-section view showing another modified example of serrations.

[0031] Figure 9 This is a cross-section view showing another modified example of serrations.

[0032] Figure 10 This is a cross-section view showing an example of a tire mold in the present invention. Detailed Description of the Invention

[0033] Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. Figure 1 This is a view showing a pneumatic tire configured according to an embodiment of the present invention, Figures 2 to 4 and this is a view showing its main part.

[0034] As Figure 1 shown, the pneumatic tire of the present embodiment includes a tread portion 1 that extends in the circumferential direction of the tire and is formed in a ring shape, a pair of sidewall portions 2, 2 disposed on both sides of the tread portion 1, and a pair of bead portions 3, 3 disposed on the radially inner side of these sidewall portions 2.

[0035] A carcass layer 4 is provided between the pair of bead portions 3, 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the radial direction of the tire and is folded back from the inner side to the outer side of the tire around a bead core 5 disposed in each bead portion 3. A bead apex 6 made of a rubber composition having a triangular cross-section is disposed on the outer periphery of the bead core 5.

[0036] On the other hand, a plurality of belt layers 7 are buried on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged in a mutually crossing manner between the layers. In the belt layer 7, the inclination angle of the reinforcing cords with respect to the tire circumferential direction is set, for example, within the range of 10° to 40°. As the reinforcing cords of the belt layer 7, steel cords are preferably used. In order to improve high-speed durability, at least one cover layer 8 in which the reinforcing cords are arranged at an angle of, for example, 5° or less with respect to the tire circumferential direction is disposed on the outer peripheral side of the belt layer 7. As the reinforcing cords of the cover layer 8, organic fiber cords such as nylon and aramid are preferably used.

[0037] It should be noted that the above-described internal structure of the tire shows a representative example of a pneumatic tire, but is not limited thereto. In addition, various grooves such as main grooves extending in the tire circumferential direction and transverse grooves extending in the tire width direction are formed in the tread portion 1.

[0038] As Figure 2 shown, a decorative portion 20 is formed in the sidewall portion 2. The decorative portion 20 includes a badge portion 21 and a background portion 22 surrounding the badge portion 21. The badge portion 21 forms letters, graphics, marks, etc., and is more recessed than the background portion 22. And, a serration 10 including a plurality of ridges 11 arranged in parallel is formed in the badge portion 21. The ridge 11 refers to a protrusion protruding from the reference plane B, and the serration 10 refers to an aggregate of the ridges 11. In addition, it may be configured such that the background portion 22 is more recessed than the badge portion 21, and a serration 10 including a plurality of ridges 11 arranged in parallel with respect to the background portion 22 is formed (refer to Figure 5 ).

[0039] As Figure 3 and Figure 4 shown, each ridge 11 has in a cross section orthogonal to the length direction of the ridge 11: a side wall surface 13 that has a negative gradient with respect to the normal line L of the reference plane B forming the ridge 11; and an inclined surface 14 that is inclined with respect to the reference plane B. That is, each ridge 11 is triangular in a cross section orthogonal to the length direction of the ridge 11. The reference plane B is a plane passing through the base ends of the plurality of side wall surfaces 13, and coincides with the bottom surface 12 between adjacent ridges 11, 11 in Figure 3 and Figure 4 . The fact that the ridge 11 has a negative gradient with respect to the normal line L of the reference plane B means that an undercut shape in which a part of the ridge 11 protrudes from the bottom surface 12 is formed. In addition, the top surface of the background portion 22 is parallel to the reference plane B.

[0040] In the above tire, each ridge 11 has a side wall surface 13 with a negative gradient with respect to the normal line L of the reference plane B. Thus, it is easy to form a shadow along the ridge 11, and light is effectively absorbed between the ridges 11, 11. In addition, each ridge 11 has an inclined surface 14 inclined with respect to the reference plane B. Thus, the inclined surface 14 effectively reflects light. Therefore, according to the structure of the above ridge 11, it is possible to emphasize the light and dark visual effect based on the serrations 10 while suppressing the height of the ridge 11 to a low level, thereby exhibiting excellent visibility.

[0041] Figure 6 It is a diagram showing an example of the light reflection state in the side wall portion. In Figure 6 assuming that the light source is located in front of the side wall portion 2, in the line-of-sight direction X1 of observing the side wall portion 2 from the front, the mark portion 21 looks black, and the background portion 22 looks luminous due to the reflection of light. In particular, since the ridge 11 has an undercut shape, the light entering between the ridges 11, 11 is difficult to be reflected, so the blackening of the mark portion 21 is promoted. On the other hand, at the line-of-sight position X2 of observing the side wall portion 2 obliquely from one direction side with respect to the front, the mark portion 21 looks luminous due to the reflection of light, and the background portion 22 looks black.

[0042] In the above tire, as Figure 4 shown, each ridge 11 preferably has a triangular shape in a cross section orthogonal to the length direction of the ridge 11. When the cross-sectional shape of the ridge 11 is set to a triangle, the light and dark visual effect can be emphasized.

[0043] In the above tire, the angle α of the side wall surface 13 with respect to the normal line L of the reference plane B can be in the range of -20° ≤ α < 0°. If the angle α is negative, it means an undercut shape, and if it is positive, it means a non-undercut shape. By setting the angle α of the side wall surface 13 to a negative gradient within the above range, the light and dark visual effect can be improved. Here, if the angle α of the side wall surface 13 is greater than 0°, the effect of absorbing light is reduced. On the contrary, if it is less than -20°, it is difficult to perform die processing. The angle α of the side wall surface 13 is particularly preferably in the range of -5° ≤ α < -15°.

[0044] In the above tire, the vertex angle β of the ridge 11 in a cross section orthogonal to the length direction of the ridge 11 can be in the range of 30° ≤ β ≤ 60°. The vertex angle β is the angle formed by the side wall surface 13 and the inclined surface 14 in a cross section orthogonal to the length direction of the ridge 11. By setting the vertex angle β of the ridge 11 within the above range, the reflection direction of light can be moderately dispersed, and the light and dark visual effect can be improved. If the vertex angle β of the ridge 11 exceeds the above range, the effect of moderately dispersing the reflection direction of light is reduced.

[0045] In the above-described tire, the pitch P of the lug 11 can be in the range of 0.5 mm to 1.2 mm, and the height of the lug 11 can be in the range of 0.2 mm to 0.5 mm. Since the lug 11 having the cross-sectional shape as described above has excellent visibility, the pitch P of the lug 11 can be increased and the height H of the lug 11 can be decreased. Therefore, the number of lugs 11 can also be reduced, and the workability of machining the tire mold can be improved. The pitch P of the lug 11 is particularly preferably in the range of 0.55 mm to 0.8 mm, and the height H of the lug 11 is particularly preferably in the range of 0.25 mm to 0.4 mm.

[0046] Figure 3 In the example of, each lug 11 is triangular in a cross-section orthogonal to the longitudinal direction of the lug 11. On the other hand, Figure 7 In the example of, each lug 11 is trapezoidal in a cross-section orthogonal to the longitudinal direction of the lug 11. That is, in Figure 7 , each lug 11 has in a cross-section orthogonal to the longitudinal direction of the lug 11: a side wall surface 13 that has a negative gradient with respect to the normal line L of the reference surface B forming the lug 11; an inclined surface 14 that is inclined with respect to the reference surface B; and a top surface 15 that connects the side wall surface 13 and the inclined surface 14. When the cross-sectional shape of the lug 11 is polygonal, the reflection direction of light changes according to the cross-sectional shape, whereby the light and dark visual effect can be made to vary.

[0047] In the above-described tire, as Figure 8 and Figure 9 shown, the lug 11 can have a chamfered portion 17 formed of a flat surface or a curved surface between the side wall surface 13 and the inclined surface 14. Figure 8 In the example of, a chamfered portion 17 formed of a flat surface is formed, Figure 9 In the example of, a chamfered portion 17 formed of a curved surface is formed. When such a chamfered portion 17 is provided, the light and dark visual effect can be made to vary by changing the absorption or reflection direction of light.

[0048] Figure 10 FIG. is a diagram showing an example of a tire mold in the present invention. Figure 10 In, only the main part of the side plate 30 that forms the side wall portion 2 of the tire is shown, and the structure of the other parts is not particularly limited, and a structure known as a tire mold can be adopted.

[0049] In the tire mold of the present invention, the molding surface 30A of the side plate 30 for molding the side wall portion 2 of the tire has a logo molding portion 31 corresponding to the logo portion 21 and a background molding portion 32 corresponding to the background portion 22, and the logo molding portion 31 protrudes more than the background molding portion 32. Further, the logo molding portion 31 is processed into a shape corresponding to the serrations 10. In this way, by vulcanizing the unvulcanized tire using the tire mold, the tire of the present invention can be molded. The tire mold includes a side plate 30 having a molding surface 30A with a shape corresponding to the logo portion 21, the background portion 22, and the serrations 10.

[0050] The processing method of the above tire mold is not particularly limited. For example, by using a double-angle cutter 40 or a dovetail cutter (not shown) as shown in Figure 10 , a molding surface 30A having a required shape can be processed.

[0051] Examples

[0052] In a tire having a logo portion and a background portion surrounding the logo portion on the side wall portion, and serrations including a plurality of ridges arranged in parallel are formed on the logo portion, tires of Comparative Example and Examples 1 to 11 with different ridge shapes are produced.

[0053] In each ridge of the Comparative Example, in a cross section orthogonal to the longitudinal direction of the ridge, there is a side wall surface at 0° with respect to the normal line of the reference plane forming the ridge and an inclined surface inclined with respect to the reference plane, and the cross-sectional shape of each ridge is triangular. In each ridge of Examples 1 to 11, in a cross section orthogonal to the longitudinal direction of the ridge, there is a side wall surface with a negative gradient with respect to the normal line of the reference plane forming the ridge and an inclined surface inclined with respect to the reference plane, and the cross-sectional shape of each ridge is triangular. In the Comparative Example and Examples 1 to 11, the angle α of the side wall surface of the ridge, the vertex angle β of the ridge, the pitch P of the ridge, and the height H of the ridge are set as shown in Table 1.

[0054] For these test tires, the visibility is evaluated by the following test method, and the results are shown in Table 1 together.

[0055] Visibility

[0056] Twenty testers visually observed the side wall portions of each test tire from various angles. At this time, the logo portion distinguished from the background portion due to light absorption or reflection was confirmed, and the visibility of the logo portion was evaluated. In the evaluation, a full score of 5 points was used, and the Comparative Example was 3 points. The evaluation result is the sum of the scores of 10 testers, and is expressed as an index with the Comparative Example set to 100. The larger the index value, the better the visibility.

[0057] [Table 1]

[0058]

[0059] As can be seen from Table 1, the tires of Examples 1 to 11 are excellent in visibility when compared with the Comparative Examples.

[0060] Description of Reference Numerals

[0061] 1: Tread surface

[0062] 2: Sidewall portion

[0063] 3: Bead portion

[0064] 10: Sawtooth

[0065] 11: Ridge

[0066] 12: Bottom surface

[0067] 13: Sidewall portion

[0068] 14: Inclined surface

[0069] 15: Top surface

[0070] 17: Chamfered portion

[0071] 20: Decorative portion

[0072] 21: Emblem portion

[0073] 22: Background portion

[0074] 30: Side plate

[0075] 30A: Molding surface

Claims

1. A tire, wherein the tire has a badge portion and a background portion surrounding the badge portion on a sidewall portion, and a serrated portion including a plurality of ridges arranged in parallel is formed in either the badge portion or the background portion, and is characterized in that each of the ridges has, in a cross section orthogonal to the longitudinal direction of the ridge: a sidewall surface that has a negative gradient with respect to the normal line of a reference plane forming the ridge; and an inclined surface that is inclined with respect to the reference plane.

2. The tire according to claim 1, characterized in that, Each of the ridges is polygonal in a cross section orthogonal to the longitudinal direction of the ridge.

3. The tire according to claim 1, characterized in that, Each of the ridges is triangular in a cross section orthogonal to the longitudinal direction of the ridge.

4. The tire according to any one of claims 1 to 3, characterized in that, The angle α of the sidewall surface with respect to the normal line of the reference plane is in the range of -20° ≤ α < 0°.

5. The tire according to any one of claims 1 to 4, characterized in that, The vertex angle β of the ridge in a cross section orthogonal to the longitudinal direction of the ridge is in the range of 30° ≤ β ≤ 60°.

6. The tire according to any one of claims 1 to 5, characterized in that, The pitch of the ridges is in the range of 0.5 mm to 1.2 mm, and the height of the ridges is in the range of 0.2 mm to 0.5 mm.

7. The tire according to any one of claims 1 to 6, characterized in that, The ridge has a chamfered portion formed of a flat surface or a curved surface between the sidewall surface and the inclined surface.

8. A tire mold for molding a tire according to any one of claims 1 to 7, characterized in that, A molding surface having a shape corresponding to the badge portion, the background portion, and the serrations is provided.

Images