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) on a side wall part (2), and a saw tooth (10) including a plurality of ridges (11) arranged in parallel is formed on 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), first and second side wall surfaces (13, 14), the convex ridge (11) has a 0-degree or negative gradient with respect to a normal (L) of a reference plane (B) forming the convex ridge (11); a first top surface (15) inclined to one side with respect to the reference surface (B); and a second top surface (16) that is inclined toward the other side with respect to the reference surface (B), the first top surface (15) and the second top surface (16) being connected to each other so as to form a recess.

Description

Technical Field

[0001] The present invention relates to a tire having serrations formed in a sidewall portion and a tire mold for molding the same. More specifically, the present invention relates to a tire and a tire mold capable of emphasizing the light and dark visual effect based on the serrations, thereby exhibiting excellent visibility. Background Art

[0002] The industry has proposed a tire in which a badge portion composed of letters, graphics, marks, etc. and a background portion surrounding the badge portion are formed in a sidewall portion of the tire, and serrations including a plurality of ridges arranged in parallel are formed in either the badge portion or the background portion (for example, refer to Patent Documents 1 to 3). When such serrations are provided on the sidewall portion, the visibility of the badge portion can be improved by utilizing the light and dark visual effect based on the serrations.

[0003] However, when emphasizing the light and dark visual effect, it is preferable to form the ridges higher, but in the sidewall portion of the tire, the height of the ridges is restricted. Therefore, the effect of improving visibility based on the ridge height is limited. In addition, for example, when the ridge has a triangular cross-sectional shape including a vertical surface and an inclined surface orthogonal to the surface of the sidewall portion, since the reflection of light is biased in one direction, sufficient visibility may not be obtained depending on the viewing angle.

[0004] Prior Art Documents

[0005] Patent Documents

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

[0007] Patent Document 2: Japanese Patent Application Laid-Open 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 capable of emphasizing the light and dark visual effect based on serrations, thereby exhibiting excellent visibility.

[0011] Means for Solving the Problems

[0012] The tire of the present invention for achieving the above object is a tire having a badge portion and a background portion surrounding the badge portion in a sidewall portion, and serrations including a plurality of ridges arranged in parallel are formed in either the badge portion or the background portion, characterized in that

[0013] Each of the ridges has, in a cross-section orthogonal to the length direction of the ridge: first and second side wall surfaces that are at 0° or have a negative gradient with respect to the normal of the reference plane forming the ridge; a first top surface that is inclined to one side with respect to the reference plane; and a second top surface that is inclined to the other side with respect to the reference plane, and the first top surface and the second top surface are connected to each other in a manner that forms a depression.

[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 first and second side wall surfaces that are at 0° or have 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 a first top surface that is inclined to one side with respect to the reference plane and a second top surface that is inclined to the other side with respect to the reference plane, and these first top surface and second top surface are connected to each other in a manner that forms a depression, whereby the first and second top surfaces effectively reflect light. Therefore, according to the above ridge structure, the light and dark visual effect can be emphasized. Moreover, when light is reflected by the first and second top surfaces, the same visual effect can be obtained whether observed from one direction side or the other direction side with respect to the front of the ridge, thereby reducing the deviation of the visual effect. Thus, 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 symmetric shape in a cross-section orthogonal to the length direction of the ridge. In this way, by making the cross-sectional shape of the ridge symmetric left and right, the deviation of the visual effect can be effectively reduced.

[0018] The angles α of the first and second side wall surfaces with respect to the normal of the reference plane are preferably each in the range of -25° ≤ α < 0°. By setting the angles α of the first and second side wall surfaces 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 ridge is preferably in the range of 0.5 mm to 1.2 mm, and the height of the ridge is preferably in the range of 0.2 mm to 0.5 mm. Since the ridge having the cross-sectional shape as described above has excellent visibility, the pitch of the ridge can be increased and the height of the ridge can be decreased.

[0021] Preferably, the gap between adjacent ridges widens toward the reference plane side of the ridge, and in a cross-section orthogonal to the length direction of the ridge, the bottom surface between adjacent ridges has a flat shape or a V-shaped shape. By widening the gap between adjacent ridges toward the reference plane side of the ridge and setting its bottom surface to a flat shape or a V-shaped shape, the reflection of light incident between adjacent ridges can be suppressed, and the light and dark visual effect can be improved.

[0022] Preferably, the ridge has a chamfered portion formed by a plane or a curved surface between the first top surface and the first side wall surface and between the second top surface and the second side wall surface, respectively. In the case where such a chamfered portion is provided, by changing the absorption or reflection direction of light, the light and dark visual effect can be made to vary.

[0023] 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

[0024] Figure 1 is a meridian cross-section of a pneumatic tire constituted by an embodiment of the present invention.

[0025] Figure 2 is a plan view showing a logo portion, a background portion, and serrations formed in the logo portion formed on the side wall portion.

[0026] Figure 3 is Figure 2 the III-III arrow cross-section of

[0027] Figure 4 is in Figure 3 the cross-section after adding dimension lines in

[0028] Figure 5 is a plan view showing a logo portion, a background portion, and serrations formed in the background portion formed on the side wall portion.

[0029] Figure 6 is a cross-section showing an example of the light reflection state in the side wall portion.

[0030] Figure 7 is a cross-section showing a modified example of the serrations.

[0031] Figure 8 is a cross-section showing another modified example of the serrations.

[0032] Figure 9 is a cross-section showing another modified example of the serrations.

[0033] Figure 10 is a cross-section showing another modified example of the serrations.

[0034] Figure 11 This is a cross-sectional view showing an example of the tire mold in the present invention. Detailed Embodiments

[0035] 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.

[0036] As Figure 1 shown, the pneumatic tire of the present embodiment includes a tread portion 1 extending in the tire circumferential direction and 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 tire radial inner side of these sidewall portions 2.

[0037] 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 tire radial direction, and is folded back from the tire inner side to the outer side around the bead cores 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.

[0038] 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 disposed to cross each other 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, in 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.

[0039] It should be noted that the above tire internal structure 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.

[0040] As Figure 2 shown, a decorative portion 20 is formed in the sidewall portion 2. The decorative portion 20 includes an emblem portion 21 and a background portion 22 surrounding the emblem portion 21. The emblem portion 21 is formed with 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 emblem 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 emblem portion 21, and a serration 10 including a plurality of ridges 11 arranged in parallel with respect to the background portion 22 is formed (seeFigure 5 )。

[0041] As Figure 3 and Figure 4 shown, each ridge 11 has in a cross-section orthogonal to the longitudinal direction of the ridge 11: a first side wall surface 13 and a second side wall surface 14, which are at 0° or a negative gradient with respect to the normal line L of the reference plane B forming the ridge 11; a first top surface 15, which is inclined to one side with respect to the reference plane B; and a second top surface 16, which is inclined to the other side with respect to the reference plane B, and the first top surface 15 and the second top surface 16 are connected to each other so as to form a depression. The reference plane B is a plane passing through the base ends of the first side wall surface 13 and the second side wall surface 14, 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.

[0042] In the above tire, each ridge 11 has a first side wall surface 13 and a second side wall surface 14 that are at 0° or a negative gradient with respect to the normal line L of the reference plane B, whereby 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 a first top surface 15 that is inclined to one side with respect to the reference plane B and a second top surface 16 that is inclined to the other side with respect to the reference plane B, and these first top surface 15 and second top surface 16 are connected to each other so as to form a depression, whereby the first top surface 15 and the second top surface 16 effectively reflect light. Therefore, according to the structure of the above ridge 11, the light and dark visual effect can be emphasized. Moreover, when light is reflected by the first top surface 15 and the second top surface 16, the same visual effect can be obtained whether observed from one direction side or the other direction side with respect to the front of the ridge 11, thereby reducing the deviation of the visual effect. As a result, 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 be low, thereby exhibiting excellent visibility.

[0043] Figure 6 is a diagram showing an example of the light reflection state in the side wall portion. In Figure 6In this case, assuming that the light source is located in front of the side wall portion 2, when viewed from the front in the line-of-sight direction X1 of the side wall portion 2, the marking portion 21 appears black, and the background portion 22 appears to glow due to light reflection. In particular, since the ridge 11 has an undercut shape, the light entering between the ridges 11, 11 is difficult to be reflected, thus promoting the blackening of the marking portion 21. On the other hand, at the line-of-sight position X2 where the side wall portion 2 is viewed obliquely from one direction side with respect to the front, and at the line-of-sight position X3 where the side wall portion 2 is viewed obliquely from the other direction side, the marking portion 21 appears to glow due to light reflection, and the background portion 22 appears black. Moreover, the same visual effect can be obtained at both the line-of-sight positions X2 and X3.

[0044] In the above tire, as Figure 4 shown, each ridge 11 preferably has a symmetric shape in a cross-section orthogonal to the length direction of the ridge 11. In this way, by making the cross-sectional shape of the ridge 11 symmetric left and right, the brightness generated by light reflection when viewed from the left and right with respect to the front is equal, and the deviation of the visual effect can be effectively reduced.

[0045] In the above tire, the angles α of the first and second side wall surfaces 13, 14 with respect to the normal line L of the reference plane B can be respectively in the range of -25° ≤ 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 angles α of the first and second side wall surfaces 13, 14 to a negative gradient within the above range, the light and dark visual effect can be improved. Here, if the angles α of the first and second side wall surfaces 13, 14 are greater than 0°, the effect of absorbing light is reduced, and conversely, if they are less than -25°, it is difficult to perform die processing. The angles α of the first and second side wall surfaces 13, 14 are particularly preferably respectively in the range of -5° ≤ α < -15°.

[0046] 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 first top surface 15 and the first side wall surface 13 or the angle formed by the second top surface 16 and the second side wall 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.

[0047] In the above-mentioned tire, the pitch P of the ridge 11 can be in the range of 0.5 mm to 1.2 mm, and the height of the ridge 11 can be in the range of 0.2 mm to 0.5 mm. Since the ridge 11 having the cross-sectional shape as described above has excellent visibility, the pitch P of the ridge 11 can be increased and the height H of the ridge 11 can be decreased. The pitch P of the ridge 11 is particularly preferably in the range of 0.6 mm to 0.8 mm, and the height H of the ridge 11 is particularly preferably in the range of 0.3 mm to 0.4 mm.

[0048] In the above-mentioned tire, the gap between adjacent ridges 11, 11 can become wider toward the reference plane B side of the ridge 11, and in a cross-section orthogonal to the longitudinal direction of the ridge 11, the bottom surface 12 between adjacent ridges 11, 11 can have a flat shape, a V-shaped, or a shape formed by combining a flat shape and a V-shaped. By making the gap between adjacent ridges 11, 11 wider toward the reference plane B side of the ridge 11 and setting the bottom surface 12 thereof to a flat shape, a V-shaped, or a shape formed by combining a flat shape and a V-shaped, the reflection of light incident between adjacent ridges 11, 11 can be suppressed, and the light and dark visual effect can be improved.

[0049] Figure 3 In the example of, the bottom surface 12 between adjacent ridges 11, 11 has a flat shape. On the other hand, Figure 7 In the example of, the bottom surface 12 between adjacent ridges 11, 11 has a V-shaped. In addition, Figure 8 In the example of, the bottom surface 12 between adjacent ridges 11, 11 has a shape formed by combining a flat shape and a V-shaped. That is, in Figure 8 , the bottom surface 12 between adjacent ridges 11, 11 is a shape having a flat surface and a pair of inclined surfaces on both sides thereof, and the flat surface is the most recessed. According to this shape, the reflection of light incident between adjacent ridges 11, 11 to the outside can be suppressed. The reference plane B is a plane passing through the base ends of the first side wall surface 13 and the second side wall surface 14, and thus does not coincide with the bottom surface 12 between adjacent ridges 11, 11 in Figure 7 and Figure 8 .

[0050] In the above-mentioned tire, as shown in Figure 9 and Figure 10 , the ridge 11 can have a chamfered portion 17 formed by a plane or a curved surface between the first top surface 15 and the first side wall surface 13 and between the second top surface 16 and the second side wall surface 14, respectively. Figure 9 In the example of, a chamfered portion 17 formed by a plane is formed, Figure 10 In the example of, a chamfered portion 17 formed by a curved surface is formed. In the case where such a chamfered portion 17 is provided, by changing the absorption or reflection direction of light, the light and dark visual effect can be made to have a change.

[0051] Figure 11 This is a view showing an example of the tire mold in the present invention. Figure 11 In this figure, only the main part of the side plate 30 for forming the side wall portion 2 of the tire is shown, and the structure of the other parts is not particularly limited, and a structure well-known as a tire mold can be adopted.

[0052] In the tire mold of the present invention, the forming surface 30A of the side plate 30 for forming the side wall portion 2 of the tire has a logo forming portion 31 corresponding to the logo portion 21 and a background forming portion 32 corresponding to the background portion 22, and the logo forming portion 31 protrudes more than the background forming portion 32. Further, the logo forming 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 formed, and the tire mold includes the side plate 30 having the forming surface 30A with a shape corresponding to the logo portion 21, the background portion 22, and the serrations 10.

[0053] The processing method of the above tire mold is not particularly limited. For example, by using a Figure 11 double-angle cutter 40 or a dovetail cutter (not shown) as shown, the forming surface 30A with the required shape can be processed.

[0054] Examples

[0055] Tires of Comparative Examples and Examples 1 to 12 with different ridge shapes were produced in a tire having a logo portion and a background portion surrounding the logo portion on the side wall portion, and the logo portion was formed with serrations including a plurality of ridges arranged in parallel.

[0056] In each ridge of the Comparative Example, in a cross-section orthogonal to the longitudinal direction of the ridge, there are first and second side wall surfaces having a positive gradient with respect to the normal line of the reference plane forming the ridge and a top surface parallel to the reference plane, and the cross-sectional shape of each ridge is trapezoidal. In each ridge of Examples 1 to 12, in a cross-section orthogonal to the longitudinal direction of the ridge, there are first and second side wall surfaces having a 0° or negative gradient with respect to the normal line of the reference plane forming the ridge, a first top surface inclined to one side with respect to the reference plane, and a second top surface inclined to the other side with respect to the reference plane, and the first top surface and the second top surface are connected to each other so as to form a depression, and the cross-sectional shape of each ridge is M-shaped. In the Comparative Example and Examples 1 to 12, the angle α of the side wall surface of the ridge, the vertex angle β of the ridge, the pitch P of the ridge, the height H of the ridge, and the shape of the bottom surface between the ridges were set as shown in Table 1.

[0057] For these test tires, the visibility was evaluated by the following test method, and the results are also shown in Table 1.

[0058] Visibility

[0059] Twenty testers visually observed the sidewall portions of each test tire from various angles, and at this time, the mark portion that was distinguishable from the background portion due to light absorption or reflection was confirmed, and the visibility of the mark portion was evaluated. When evaluating, a score was given out of 5 points, with the comparative example being 3 points. The evaluation result was obtained by finding the sum of the scores of 10 testers and expressing it as an index with the comparative example set to 100. The larger the index value, the more excellent the visibility.

[0060] [Table 1]

[0061]

[0062] As can be seen from Table 1, the tires of Examples 1 to 12 have excellent visibility in comparison with the comparative example.

[0063] Explanation of reference numerals

[0064] 1: Tread surface

[0065] 2: Sidewall portion

[0066] 3: Bead portion

[0067] 10: Sawtooth

[0068] 11: Ridge

[0069] 12: Bottom surface

[0070] 13: First sidewall portion

[0071] 14: Second sidewall portion

[0072] 15: First top surface

[0073] 16: Second top surface

[0074] 17: Chamfered portion

[0075] 20: Decorative portion

[0076] 21: Mark portion

[0077] 22: Background portion

[0078] 30: Side plate

[0079] 30A: Molding surface

Claims

1. A tire, wherein the tire has an emblem portion and a background portion surrounding the emblem portion on a sidewall portion, and a serration including a plurality of ridges arranged in parallel is formed in either the emblem 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: first and second sidewall surfaces that are at 0° or have a negative gradient with respect to the normal of the reference plane forming the ridge; a first top surface that is inclined with respect to the reference plane to one side; and a second top surface that is inclined with respect to the reference plane to the other side, and the first top surface and the second top surface are connected to each other in a manner that forms a recess.

2. The tire according to claim 1, characterized in that, Each of the ridges has a symmetric shape in a cross-section orthogonal to the longitudinal direction of the ridge.

3. The tire according to claim 1 or 2, characterized in that, The angles α of the first and second sidewall surfaces with respect to the normal of the reference plane are each in the range of -25° ≤ α < 0°.

4. The tire according to any one of claims 1 to 3, 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°.

5. The tire according to any one of claims 1 to 4, 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.

6. The tire according to any one of claims 1 to 5, characterized in that, The gap between adjacent ridges widens toward the reference plane side of the ridges, and in a cross-section orthogonal to the longitudinal direction of the ridges, the bottom surface between adjacent ridges has a flat shape or a V-shaped.

7. The tire according to any one of claims 1 to 6, characterized in that, The ridges each have a chamfer portion formed of a flat surface or a curved surface between the first top surface and the first sidewall surface and between the second top surface and the second sidewall surface.

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

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