JP2024082398A - Tires and tire moulds - Google Patents

Abstract

[Problem] To provide a tire and tire mold that emphasize the visual effect of light and dark based on serrations and enable excellent visibility. [Solution] In a tire having a marking portion 21 and a background portion 22 surrounding the marking portion 21 in a sidewall portion 2, and serrations 10 including a plurality of ridges 11 arranged in parallel formed on either the marking portion 21 or the background portion 22, each of the ridges 11 has, in a cross section perpendicular to the longitudinal direction of the ridge 11, first and second sidewall surfaces 13, 14 that are inclined at 0° or a negative gradient with respect to a normal line L of a reference plane B on which the ridge 11 is formed, 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 the first top surface 15 and the second top surface 16 are connected to each other so as to form a recess. [Selected Figure] Figure 3

Description

The present invention relates to a tire with serrations formed in the sidewall and a tire mold for molding the tire, and more specifically, to a tire and tire mold that emphasizes the visual effect of light and dark based on the serrations, making it possible to achieve excellent visibility.

A tire has been proposed in which a marking portion consisting of letters, figures, symbols, etc. and a background portion surrounding the marking portion are formed on the sidewall of the tire, and serrations including multiple ridges arranged in parallel are formed on either the marking portion or the background portion (see, for example, Patent Documents 1 to 3). When such serrations are provided on the sidewall portion, the visibility of the marking portion can be improved by the visual effect of light and dark based on the serrations.

However, while it is desirable to form the ridge high in order to emphasize the visual effect of light and dark, the height of the ridge is restricted in the sidewall portion of the tire. Therefore, there is a limit to the effect of improving visibility based on the height of the ridge. Also, for example, if the ridge has a triangular cross-sectional shape that includes a vertical surface perpendicular to the surface of the sidewall portion and an inclined surface, light reflection is biased in one direction, and sufficient visibility may not be obtained depending on the viewpoint.

JP 2003-175707 A JP 2019-147495 A JP 2020-6863 A

The object of the present invention is to provide a tire and tire mold that enhances the visual effect of light and dark based on serrations and provides excellent visibility.

In order to achieve the above object, a tire of the present invention has a mark portion and a background portion surrounding the mark portion on a sidewall portion, and serrations including a plurality of ridges arranged in parallel are formed on either the mark portion or the background portion,
Each of the ridges has, in a cross section perpendicular to the longitudinal direction of the ridge, first and second side wall surfaces that have a 0° or negative gradient with respect to the normal to a reference plane on which the ridge is formed, 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 so as to form a recess.

The tire mold of the present invention, which is used to achieve the above object, is a tire mold for molding the above-mentioned tire, and is characterized by having a molding surface having a shape corresponding to the marking portion, the background portion, and the serrations.

In the present invention, each of the ridges has a first and second sidewall surface that is inclined at 0° or a negative gradient with respect to the normal to the reference plane, which makes it easier for a shadow to be formed along the ridge and effectively absorbs light between the ridges. In addition, each of the ridges 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 and second top surfaces are connected to each other to form a recess, so that the first and second top surfaces effectively reflect light. Therefore, the above ridge structure can emphasize the visual effect of light and dark. Moreover, when light is reflected at the first and second top surfaces, the same visual effect can be obtained whether viewed from one side or the other side with respect to the front of the ridge, and the bias of the visual effect can be reduced. This makes it possible to emphasize the visual effect of light and dark based on the serration while keeping the height of the ridge low, thereby providing excellent visibility.

In the present invention, it is preferable that each ridge has a symmetrical shape in a cross section perpendicular to the longitudinal direction of the ridge. By making the cross-sectional shape of the ridge symmetrical in this way, it is possible to effectively reduce bias in the visual effect.

It is preferable that the angle α of the first and second side wall surfaces with respect to the normal to the reference surface is in the range of -25°≦α<0°. By setting the angle α of the first and second side wall surfaces within the above range, the visual effect of light and dark can be improved.

The apex angle β of the ridge in a cross section perpendicular to the longitudinal direction of the ridge is preferably in the range of 30°≦β≦60°. By setting the apex angle of the ridge in the above range, the visual effect of light and dark can be enhanced.

It is preferable that the ridge pitch is in the range of 0.5 mm to 1.2 mm and the ridge height is in the range of 0.2 mm to 0.5 mm. Ridges having the cross-sectional shape described above have excellent visibility, so it is possible to increase the ridge pitch and decrease the ridge height.

It is preferable that the gap between adjacent ridges widens toward the reference surface side of the ridge, and that in a cross section perpendicular to the longitudinal direction of the ridge, the bottom surface between adjacent ridges has a flat or V-shape. By widening the gap between adjacent ridges toward the reference surface side of the ridge and making the bottom surface flat or V-shaped, it is possible to suppress the reflection of light that penetrates between adjacent ridges and enhance the visual effect of light and dark.

It is preferable that the ridge has a chamfered portion consisting of a flat surface 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. When such a chamfered portion is provided, the direction of light absorption and reflection can be changed, thereby providing a variety in the visual effect of light and dark.

The tire of the present invention may be a pneumatic tire or a non-pneumatic tire. In the case of a pneumatic tire, the inside of the tire can be filled with air, an inert gas such as nitrogen, or other gases. Non-pneumatic tires include solid tires.

1 is a meridian cross-sectional view showing a pneumatic tire according to an embodiment of the present invention. 1 is a plan view showing a mark portion formed in a sidewall portion, a background portion, and serrations formed in the mark portion. FIG. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2 . FIG. 4 is a cross-sectional view of FIG. 3 with dimension lines. 1 is a plan view showing a marking portion formed on a sidewall portion, a background portion, and serrations formed on the background portion. FIG. 4 is a cross-sectional view showing an example of a state in which light is reflected at a sidewall portion. FIG. FIG. 11 is a cross-sectional view showing a modified example of the serration. FIG. 11 is a cross-sectional view showing another modified example of the serration. FIG. 11 is a cross-sectional view showing another modified example of the serration. FIG. 11 is a cross-sectional view showing another modified example of the serration. FIG. 1 is a cross-sectional view showing an example of a tire mold in the present invention.

The configuration of the present invention will be described in detail below with reference to the attached drawings. Figure 1 shows a pneumatic tire according to an embodiment of the present invention, and Figures 2 to 4 show the main parts of the tire.

As shown in FIG. 1, the pneumatic tire of this embodiment has a tread portion 1 that extends in the circumferential direction of the tire and forms an annular shape, a pair of sidewall portions 2, 2 arranged on both sides of the tread portion 1, and a pair of bead portions 3, 3 arranged on the radially inner side of the sidewall portions 2.

A carcass layer 4 is fitted between a pair of bead portions 3, 3. This carcass layer 4 includes multiple reinforcing cords extending in the tire radial direction, and is folded back from the inside to the outside of the tire around a bead core 5 arranged in each bead portion 3. A bead filler 6 made of a rubber composition with a triangular cross section is arranged on the outer periphery of the bead core 5.

On the other hand, multiple belt layers 7 are embedded on the outer periphery of the carcass layer 4 in the tread portion 1. These belt layers 7 include multiple reinforcing cords that are inclined with respect to the tire circumferential direction, and are arranged so that the reinforcing cords cross each other between layers. In the belt layers 7, the inclination angle of the reinforcing cords with respect to the tire circumferential direction is set to a range of, for example, 10° to 40°. Steel cords are preferably used as the reinforcing cords of the belt layers 7. At least one belt cover layer 8 is arranged on the outer periphery of the belt layers 7, in which reinforcing cords are arranged at an angle of, for example, 5° or less with respect to the tire circumferential direction, with the aim of improving high-speed durability. Organic fiber cords such as nylon and aramid are preferably used as the reinforcing cords of the belt cover layer 8.

The above-mentioned tire internal structure shows a typical example of a pneumatic tire, but is not limited to this. In addition, various grooves such as main grooves extending in the tire circumferential direction and lug grooves extending in the tire width direction are formed in the tread portion 1.

As shown in FIG. 2, the sidewall portion 2 is formed with a decorative portion 20. The decorative portion 20 includes a mark portion 21 and a background portion 22 surrounding the mark portion 21. The mark portion 21 forms a character, a figure, a symbol, etc., and is recessed from the background portion 22. The mark portion 21 is formed with serrations 10 including a plurality of ridges 11 arranged in parallel. The ridges 11 are protruding stripes protruding from the reference plane B, and the serrations 10 are a collection of the ridges 11. The background portion 22 may be recessed from the mark portion 21, and the serrations 10 may be formed with a plurality of ridges 11 arranged in parallel to the background portion 22 (see FIG. 5).

3 and 4, each of the ridges 11 has a first sidewall surface 13 and a second sidewall surface 14 that are inclined at 0° or a negative gradient with respect to the normal line L of the reference plane B on which the ridge 11 is formed, 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, in a cross section perpendicular to the longitudinal direction of the ridge 11, and the first top surface 15 and the second top surface 16 are connected to each other to form a recess. The reference plane B is a plane passing through the base ends of the first sidewall surface 13 and the second sidewall surface 14, and in FIG. 3 and FIG. 4, it coincides with the bottom surface 12 between the adjacent ridges 11, 11. The fact that the ridge 11 has a negative gradient with respect to the normal line L of the reference plane B means that a part of the ridge 11 forms an undercut shape protruding above the bottom surface 12. The top surface of the background portion 22 is parallel to the reference plane B.

In the above-mentioned tire, each of the ridges 11 has a first sidewall surface 13 and a second sidewall surface 14 that are inclined at 0° or a negative gradient with respect to the normal line L of the reference plane B, so that a shadow is easily formed along the ridge 11, and light is effectively absorbed between the ridges 11, 11. In addition, each of the ridges 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 surfaces 15 and second top surfaces 16 are connected to each other to form a recess, so that the first top surface 15 and the second top surface 16 effectively reflect light. Therefore, according to the structure of the ridge 11, the visual effect of light and dark 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 viewed from one side or the other side with respect to the front of the ridge 11, and the bias of the visual effect can be reduced. This allows the height of the ridge 11 to be kept low while emphasizing the visual effect of light and dark created by the serrations 10, providing excellent visibility.

Figure 6 shows an example of the state of light reflection in the sidewall portion. In Figure 6, assuming that a light source is located in front of the sidewall portion 2, in the line of sight X1 when the sidewall portion 2 is viewed from the front, the marking portion 21 appears black, and the background portion 22 appears shiny due to the reflection of light. In particular, the ridge 11 has an undercut shape, and light that penetrates between the ridges 11, 11 is not easily reflected, which promotes the blackening of the marking portion 21. On the other hand, at line of sight X2 when the sidewall portion 2 is viewed obliquely from one side relative to the front, and at line of sight X3 when the sidewall portion 2 is viewed obliquely from the other side, the marking portion 21 appears shiny due to the reflection of light, and the background portion 22 appears black. Moreover, the same visual effect can be obtained at both line of sight X2 and X3.

In the above tire, as shown in Figure 4, it is preferable that each of the ridges 11 has a symmetrical shape in a cross section perpendicular to the longitudinal direction of the ridge 11. By making the cross-sectional shape of the ridges 11 symmetrical in this way, the brightness due to the reflection of light when viewed from the left and right sides of the front is equal, and the bias in the visual effect can be effectively reduced.

In the above tire, the angle α of the first and second sidewall surfaces 13, 14 with respect to the normal line L of the reference plane B is preferably in the range of -25°≦α<0°. A negative value of the angle α indicates an undercut shape, and a positive value indicates a non-undercut shape. By making the angle α of the first and second sidewall surfaces 13, 14 negatively sloping in the above range, the visual effect of light and dark can be enhanced. Here, if the angle α of the first and second sidewall surfaces 13, 14 is larger than 0°, the light absorption effect decreases, and conversely, if it is smaller than -25°, die processing becomes difficult. In particular, it is desirable that the angle α of the first and second sidewall surfaces 13, 14 is in the range of -5°≦α<-15°.

In the above tire, the apex angle β of the ridge 11 in a cross section perpendicular to the longitudinal direction of the ridge 11 is preferably in the range of 30°≦β≦60°. The apex angle β is the angle between the first top surface 15 and the first sidewall surface 13 or the angle between the second top surface 16 and the second sidewall surface 14 in a cross section perpendicular to the longitudinal direction of the ridge 11. By setting the apex angle β of the ridge 11 in the above range, the direction of light reflection can be appropriately dispersed, enhancing the visual effect of light and dark. If the apex angle β of the ridge 11 is outside the above range, the effect of appropriately dispersing the direction of light reflection decreases.

In the above tire, it is preferable that the pitch P of the ridge 11 is in the range of 0.5 mm to 1.2 mm, and the height H of the ridge 11 is in the range of 0.2 mm to 0.5 mm. Since the ridge 11 having the above-mentioned cross-sectional shape has excellent visibility, it is possible to increase the pitch P of the ridge 11 and decrease the height H of the ridge 11. In particular, it is preferable that the pitch P of the ridge 11 is in the range of 0.6 mm to 0.8 mm, and the height H of the ridge 11 is in the range of 0.3 mm to 0.4 mm.

In the above tire, the gap between adjacent ridges 11, 11 is wider toward the reference plane B side of the ridge 11, and in a cross section perpendicular to the longitudinal direction of the ridge 11, the bottom surface 12 between adjacent ridges 11, 11 may have a flat shape, a V shape, or a shape that combines a flat shape and a V shape. By widening the gap between adjacent ridges 11, 11 toward the reference plane B side of the ridge 11 and making the bottom surface 12 flat or V shape, or a shape that combines a flat shape and a V shape, it is possible to suppress the reflection of light that penetrates between adjacent ridges 11, 11 and enhance the visual effect of light and dark.

3, the bottom surface 12 between the adjacent ridges 11, 11 has a flat shape. On the other hand, in the example of FIG. 7, the bottom surface 12 between the adjacent ridges 11, 11 has a V-shape. Also, in the example of FIG. 8, the bottom surface 12 between the adjacent ridges 11, 11 has a shape that combines a flat shape and a V-shape. That is, in FIG. 8, the bottom surface 12 between the adjacent ridges 11, 11 has a flat surface and a pair of inclined surfaces located on both sides thereof, and the flat surface has a shape that is the most recessed. With such a shape, it is possible to suppress the reflection of light that has entered between the adjacent ridges 11, 11 to the outside. Since the reference plane B is a plane that passes through the base ends of the first side wall surface 13 and the second side wall surface 14, it does not coincide with the bottom surface 12 between the adjacent ridges 11, 11 in FIG. 7 and FIG. 8.

As shown in Figures 9 and 10, in the above tire, the ridge 11 may have chamfered portions 17 made of a flat or curved surface between the first top surface 15 and the first sidewall surface 13, and between the second top surface 16 and the second sidewall surface 14. In the example of Figure 9, a chamfered portion 17 made of a flat surface is formed, and in the example of Figure 10, a chamfered portion 17 made of a curved surface is formed. When such a chamfered portion 17 is provided, the direction of light absorption and reflection can be changed, resulting in a variety of light and dark visual effects.

Figure 11 shows an example of a tire mold according to the present invention. In Figure 11, only the main parts of the side plate 30 that molds the sidewall portion 2 of the tire are depicted, but the configuration of the other parts is not particularly limited, and any known structure can be used for a tire mold.

In the tire mold of the present invention, the molding surface 30A of the side plate 30 that molds the sidewall portion 2 of the tire has a mark molding portion 31 that corresponds to the mark portion 21 and a background molding portion 32 that corresponds to the background portion 22, and the mark molding portion 31 protrudes beyond the background molding portion 32. The mark molding portion 31 is processed into a shape that corresponds to the serrations 10. In this way, the tire according to the present invention can be molded by vulcanizing an unvulcanized tire using a tire mold that includes a side plate 30 having a molding surface 30A that has a shape that corresponds to the mark portion 21, the background portion 22, and the serrations 10.

The machining method for the tire mold described above is not particularly limited, but for example, a double angular cutter 40 as shown in FIG. 11 or a dovetail cutter (not shown) can be used to machine the molding surface 30A into the desired shape.

For a tire that has a marking portion on the sidewall and a background portion surrounding the marking portion, and in which serrations including multiple ridges arranged in parallel are formed on the marking portion, tires were manufactured as comparative examples and examples 1 to 12 with various different ridge shapes.

Each ridge of the comparative example has, in a cross section perpendicular to the longitudinal direction of the ridge, first and second sidewall surfaces that have a positive gradient with respect to the normal to the reference plane on which the ridge is formed, and a top surface that is parallel to the reference plane, and has a trapezoidal cross-sectional shape. Each ridge of the examples 1 to 12 has, in a cross section perpendicular to the longitudinal direction of the ridge, first and second sidewall surfaces that have a gradient of 0° or a negative gradient with respect to the normal to the reference plane on which the ridge is formed, 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 and second top surfaces are connected to each other to form a recess, and the cross-sectional shape is M-shaped. In the comparative example and examples 1 to 11, the angle α of the sidewall surface of the ridge, the apex 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.

The visibility of these test tires was evaluated using the following test method, and the results are shown in Table 1.

Visibility:
Twenty testers visually inspected the sidewall of each test tire from various angles, and confirmed the markings that were distinguished from the background due to light absorption or reflection, and evaluated the visibility of the markings. The evaluation was conducted on a 5-point scale, with the comparative example receiving 3 points. The evaluation results were calculated by adding up the evaluation points of the 10 testers and expressed as an index with the comparative example receiving 100. The higher the index value, the better the visibility.

As can be seen from Table 1, the tires of Examples 1 to 12 had superior visibility compared to the comparative example.

The present disclosure includes the following inventions [1] to [8].
Invention [1] is a tire having a mark portion and a background portion surrounding the mark portion on a sidewall portion, and serrations including a plurality of ridges arranged in parallel are formed on either the mark portion or the background portion,
The tire is characterized in that each of the ridges, in a cross section perpendicular to the longitudinal direction of the ridge, has first and second side wall surfaces that have a 0° or negative gradient with respect to the normal to a reference plane on which the ridge is formed, a first top surface that slopes to one side with respect to the reference plane, and a second top surface that slopes 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 recess.
Invention [2] is the tire according to invention [1], characterized in that each of the ridges has a symmetrical shape in a cross section perpendicular to the longitudinal direction of the ridge.
Invention [3] is the tire according to invention [1] or [2], characterized in that the angles α of the first and second side wall surfaces with respect to the normal to the reference plane are each in the range of −25°≦α<0°.
Invention [4] is the tire according to any one of inventions [1] to [3], characterized in that the apex angle β of the ridge in a cross section perpendicular to the longitudinal direction of the ridge is in the range of 30°≦β≦60°.
Invention [5] is a tire according to any one of inventions [1] to [4], characterized in that the ridge pitch is in the range of 0.5 mm to 1.2 mm, and the ridge height is in the range of 0.2 mm to 0.5 mm.
Invention [6] is a tire according to any one of inventions [1] to [5], characterized in that the gap between adjacent ridges becomes wider toward the reference plane side of the ridge, and in a cross section perpendicular to the longitudinal direction of the ridge, the bottom surface between adjacent ridges has a flat shape or a V-shape.
Invention [7] is a tire according to any one of inventions [1] to [6], characterized in that the ridge has chamfered portions, each of which is 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.
Invention [8] is a tire mold for molding the tire according to any one of Inventions [1] to [7], characterized in that the tire mold has a molding surface having shapes corresponding to the mark portion, the background portion, and the serrations.

REFERENCE SIGNS LIST 1 tread portion 2 sidewall portion 3 bead portion 10 serration 11 ridge 12 bottom surface 13 first sidewall surface 14 second sidewall surface 15 first top surface 16 second top surface 17 chamfered portion 20 decorative portion 21 emblem portion 22 background portion 30 side plate 30A molding surface

Claims (8)

A tire having a mark portion and a background portion surrounding the mark portion on a sidewall portion, and serrations including a plurality of ridges arranged in parallel are formed on either the mark portion or the background portion,
Each of the ridges has, in a cross section perpendicular to the longitudinal direction of the ridge, first and second side wall surfaces that have a 0° or negative gradient with respect to a normal to a reference plane on which the ridge is formed, 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 so as to form a recess. The tire according to claim 1, characterized in that each of the ridges has a symmetrical shape in a cross section perpendicular to the longitudinal direction of the ridge. The tire described in claim 1, characterized in that the angle α of the first and second sidewall surfaces relative to the normal to the reference plane is in the range of -25°≦α<0°. The tire according to claim 1, characterized in that the apex angle β of the ridge in a cross section perpendicular to the longitudinal direction of the ridge is in the range of 30°≦β≦60°. The tire described in claim 1, characterized in that the pitch of the ridge is in the range of 0.5 mm to 1.2 mm, and the height of the ridge is in the range of 0.2 mm to 0.5 mm. The tire described in claim 1, characterized in that the gap between adjacent ridges is wider toward the reference surface side of the ridge, and in a cross section perpendicular to the longitudinal direction of the ridge, the bottom surface between adjacent ridges has a flat shape or a V-shape. The tire according to claim 1, characterized in that the ridge has chamfered portions consisting 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. A tire mold for molding the tire according to any one of claims 1 to 7, characterized in that the tire mold has a molding surface having a shape corresponding to the marking portion, the background portion, and the serrations.

Images