JP7085454B2 - tire - Google Patents

Description

Embodiments of the present invention relate to a tire to which a stud is attached to a tread portion.

As a tire that improves running performance on ice and snow roads, a studded tire (also called a spike tire) is known in which a stud (tack) made of metal or the like is driven into the tread portion.

The stud is attached to the mounting hole provided in the tread portion. The mounting holes are formed by mounting hole forming protrusions provided on the vulcanization mold during vulcanization molding of the tire. Conventionally, in order to prevent the stud from coming off the mounting hole when the tire is running, a large bulge is provided at the bottom of the mounting hole, and a flange portion that fits into the bulge is provided at the lower end of the stud (see Patent Document 1). ).

In addition, Patent Document 2 describes that a plurality of inclined annular grooves are provided in the body of the stud in order to prevent the stud arranged in the shoulder region of the tread surface from falling off. However, it is not described that the body of the stud and the mounting hole are provided with threaded portions that are screwed together.

Japanese Unexamined Patent Publication No. 2017-074924 Japanese Unexamined Patent Publication No. 2017-213960

It is an object of the present invention to provide a tire capable of preventing the stud from coming off when the tire is running.

The tire according to the embodiment of the present invention is a tire including a stud and a tread rubber having a mounting hole for which the stud is attached, and the stud has a columnar body and an outer peripheral surface of the body. The mounting hole is provided with a male threaded portion provided, the mounting hole is provided with a female threaded portion on an inner peripheral surface, and the stud is fixed to the mounting hole by screwing the male threaded portion into the female threaded portion.

According to the present embodiment, the female threaded portion is provided in the mounting hole provided in the tread rubber, and the male threaded portion is provided on the outer peripheral surface of the body of the stud, so that the male threaded portion is screwed into the female threaded portion and the stud is used as the mounting hole. Can be fastened and fixed. Therefore, it is possible to prevent the stud from falling off from the mounting hole.

Semi-cross-sectional view of the tire according to one embodiment The figure which shows the tread pattern of the tire which concerns on one Embodiment Side view of the stud according to one embodiment Sectional drawing of the mounting hole which concerns on one Embodiment Cross-sectional view of the mounting hole to which the stud according to the embodiment is mounted. Sectional view of studs and mounting holes according to other embodiments

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the tire 10 according to the embodiment is a pneumatic tire, and is a studded tire in which a stud 40 is attached to a tread portion 12. The tire 10 includes a tread portion 12, a pair of left and right bead portions 14, and a pair of left and right sidewall portions 16 interposed between the tread portion 12 and the bead portion 14. In the figure, reference numeral CL indicates a tire equatorial plane corresponding to the center in the tire axial direction.

The tire 10 includes a carcass layer 18 that extends toroidally across the pair of bead portions 14. The tread portion 12 is provided with a belt layer 20 on the radial outer side of the carcass layer 18, and a tread rubber 22 is laminated on the radial outer side of the belt layer 20. The tread rubber 22 has a two-layer structure including a cap rubber layer 26 having a tread surface 24 in contact with the road surface and a base rubber layer 28 arranged radially inside the cap rubber layer 26. The tread surface 24 is an outer peripheral surface of the tread portion 12 forming a ground contact surface. A general tire structure can be adopted for parts other than the tread portion 12.

The base rubber layer 28 is made of rubber having a higher hardness than the cap rubber layer 26. That is, the rubber hardness of the base rubber layer 28 is higher than the rubber hardness of the cap rubber layer 26. The rubber hardness values of the rubber layers 26 and 28 are not particularly limited, but may be, for example, the rubber hardness of the cap rubber layer 26 may be 45 to 60, and the rubber hardness of the base rubber layer 28 may be 60 to 75. Here, the rubber hardness is JIS K6253-1-2012 3.2 durometer hardness (durometer hardness), and is measured in an atmosphere of 23 ° C. using a type A durometer for general rubber (medium hardness). Ru.

As shown in FIG. 2, the tread portion 12 is provided with a main groove 30 extending in the tire circumferential direction and a lateral groove 32 extending in a direction intersecting the main groove 30, and a plurality of land portions 34 such as blocks and ribs are divided. It is formed. A plurality of sipes 36 are provided on the land portion 34.

As shown in FIGS. 1 and 2, a plurality of mounting holes 38 are provided in the land portion 34 of the tread portion 12, and studs 40 are attached to each mounting hole 38.

As shown in FIG. 3, the stud 40 includes a columnar body 42 and a convex portion 44 provided at the upper end of the body 42 in the axial direction and in contact with the road surface. The stud 40 is made of, for example, metal. Here, the upper end of the body 42 is an end located on the tread surface 24 side in a state of being attached to the tire (that is, an end on the outer side in the radial direction of the tire). Unless otherwise specified, terms that describe the vertical relationship such as upper, upper, upper, lower, lower, lower, and lower also mean the vertical relationship of the tire, with the outer side in the radial direction of the tire as the upper side and the tire. The inner side in the radial direction is expressed as the lower side.

The body 42 is a portion to be fitted into the mounting hole 38, and is mounted in the mounting hole 38 from the other end side in the axial direction, that is, the lower end side. The body 42 has a columnar shape in this example. The size of the body 42 is not particularly limited, and may be, for example, a diameter of 5.0 to 7.0 mm and a length of 7.0 to 11.0 mm.

A male screw portion 46 formed of a spiral groove is provided on the outer peripheral surface of the body 42. In this example, the male threaded portion 46 is provided at the lower part of the body 42, and more specifically, the outer peripheral surface of the lower half of the body 42 is formed on the male threaded portion 46, and the upper half has a threaded portion. It is formed in a columnar portion (columnar portion in this example) 48 having no constant cross section. The lower end of the stud 40 is not provided with a bulging portion such as a flange that extends in the direction perpendicular to the axis to prevent the stud 40 from coming off.

The convex portion 44 protrudes in the axial direction from the upper end surface which is one end surface in the axial direction of the body 42, and is exposed (protruded) from the mounting hole 38 to exert a scratching effect on the ice and snow road surface as shown in FIG. It is also called a stud core. The convex portion 44 is formed to have a smaller outer shape than the body 42 in this example. The shape of the convex portion 44 is not particularly limited, and may be, for example, a columnar or a prismatic shape.

As shown in FIG. 4, the mounting hole 38 is provided in the tread rubber 22 and is a bottomed hole that sinks inward in the radial direction of the tire from the tread surface 24. The mounting hole 38 has a pillar-shaped inner peripheral surface 38A to which the stud 40 is mounted. The inner peripheral surface 38A of the mounting hole 38 has a cylindrical surface shape in this example.

The mounting hole 38 includes a female threaded portion 50 formed of a spiral groove on its inner peripheral surface 38A. The female threaded portion 50 is formed so as to be screwable with the male threaded portion 46 of the stud 40. In order to form the female threaded portion 50 in the mounting hole 38, although not shown, the female threaded portion 50 is formed on the outer peripheral surface of the columnar mounting hole forming protrusion for molding the mounting hole 38 in the vulcanization die of the tire. The corresponding spiral streaks may be provided.

The female screw portion 50 is provided on the bottom 38B side of the mounting hole 38 in this example. Specifically, the inner peripheral surface 38A of the lower half of the mounting hole 38 is formed in the female screw portion 50, and the upper half is a pillar-shaped portion having a constant cross section having no threaded portion (cylindrical surface-shaped portion in this example). It is formed at 52.

More specifically, the mounting hole 38 is formed by being recessed so that the bottom portion 38B thereof enters the base rubber layer 28. That is, the mounting hole 38 extends inward in the radial direction beyond the boundary surface 27 between the cap rubber layer 26 and the base rubber layer 28, and the bottom portion 38B of the mounting hole 38 is surrounded by the base rubber layer 28. .. Since the mounting hole 38 is formed by pushing the protrusion for forming the mounting hole into the surface of the tread rubber of the green tire, as shown in FIG. 4, the portion that has entered the base rubber layer 28 has a cap on the surface thereof. A rubber film 29 made of rubber of the rubber layer 26 is provided.

In this example, the female thread portion 50 is provided on the bottom portion 38B side in the depth direction of the mounting hole 38. That is, the female screw portion 50 is provided on the inner peripheral surface 38A of the bottom portion 38B that has entered the base rubber layer 28.

As shown in FIG. 5, the stud 40 is mounted and fixed by screwing it into the mounting hole 38. That is, the stud 40 is inserted into the mounting hole 38 from the male threaded portion 46 side at the lower end thereof, and the body 42 of the stud 40 is screwed into the female threaded portion 50 of the mounting hole 38 while the male threaded portion 46 is screwed into the bottom surface of the mounting hole 38 (that is, that is). , Lower end) Insert up to 38C and fix. As a result, the entire body 42 of the stud 40 enters the mounting hole 38, and the convex portion 44 at the upper end protrudes from the tread surface 24. At this time, there is no cavity below the body 42 (that is, inward in the radial direction of the tire), and the lower end of the stud 40 (that is, the lower surface of the body 42) is supported by the support surface with the bottom surface 38C of the mounting hole 38 as the support surface. It is in a state of being.

As described above, according to the present embodiment, the stud 40 can be fixed to the mounting hole 38 by engaging the female threaded portion 50 provided in the mounting hole 38 with the male threaded portion 46 provided in the stud 40, and the mounting hole 38 can be fixed. It is possible to prevent the stud 40 from falling off from the stud 40.

Further, since it is fixed by screwing the male screw portion 46 and the female screw portion 50 and does not provide a large bulge at the bottom of the mounting hole 38, the protrusion for forming the mounting hole is formed on the tread rubber 22 after the tire vulcanization molding. It can be easily removed from the mold, and the resistance at the time of demolding (that is, the resistance to remove the kettle) can be reduced.

Further, since the stud 40 is fixed so that the convex portion 44 protrudes from the tread surface 24 and there is no cavity below the stud 40, the stud 40 is supported by the bottom surface 38B of the mounting hole 38 when the tire 10 is in contact with the ground. It stabilizes and can exert its function.

Further, in this embodiment, the mounting holes 38 are provided up to the base rubber layer 28, and the female screw portion 50 is provided on the bottom portion 38B side surrounded by the base rubber layer 28. Since the base rubber layer 28 has a higher hardness than the cap rubber layer 26, by providing the female threaded portion 50 on the bottom portion 38B side having a high hardness, the screwing strength with the male threaded portion 46 is increased and the stud 40 is made more difficult to come off. be able to.

In the above embodiment, the female screw portion 50 is provided only on the bottom 38B side of the mounting hole 38, and the male screw portion 46 is also provided only on the lower side of the body 42. This is because it is preferable to provide the female screw portion 50 at least on the bottom 38B side in the depth direction of the mounting hole 38 from the viewpoint of preventing the stud 40 from coming off. In order to further enhance the effect of preventing disconnection, it is preferable to provide the female threaded portion 50 in the entire depth direction of the mounting hole 38 and the male threaded portion 46 in the entire axial direction of the body 42. The female threaded portion 50 is preferably provided in a range of, for example, 20% or more of the depth of the mounting hole 38 from the bottom surface 38C of the mounting hole 38, and the male threaded portion 46 is, for example, the length in the axial direction from the lower end of the body 42. It is preferably provided in the range of 20% or more of the shavings.

It is preferable that the thread height H1 (see FIG. 4) of the female threaded portion 50 of the mounting hole 38 is formed to be larger than the thread height H2 (see FIG. 3) of the male threaded portion 46 of the stud 40 (see FIG. 3). That is, H1> H2). By increasing the height H1 of the thread of the female thread 50, the thread of the female thread 50 is compressed and an inward tightening force is generated at the time of screwing with the male thread 46. Therefore, the screwing strength with the male screw portion 46 can be increased to make it more difficult for the stud 40 to come off. For example, the thread height H1 of the female thread portion 50 is preferably about 1.1 to 1.3 times the thread height H2 of the male thread portion 46 (that is, H2 × 1.1 ≦ H1 ≦ H2). × 1.3).

The height H1 of the thread of the female thread portion 50 is not particularly limited, but is preferably 1.0 to 2.0 mm, for example. When H1 is 1.0 mm or more, the stud 40 can be made more difficult to come off. Further, when H1 is 2.0 mm or less, it is possible to suppress an increase in the resistance to pulling out the hook after vulcanization and molding of the tire.

The shape of the tooth of the screw with respect to the male screw portion 46 and the female screw portion 50 is not particularly limited, and examples thereof include a triangular screw, a square screw, a trapezoidal screw, a sawtooth screw, and a round screw.

In one embodiment, as shown in FIG. 6, it is preferable that the female screw portion 50 has a thread 54 of a sawtooth screw in which the angle θ2 of the slope 54B on the bottom side is smaller than the angle θ1 of the slope 54A on the opening side.

Here, the slope 54A on the opening side is a slope on the side (that is, the upper side) closer to the opening surface (same as the tread surface 24) of the mounting hole 38 among the slopes on both sides of the thread 54, and is on the bottom side. The slope 54B is a slope on both sides of the thread, which is closer to the bottom surface 38C of the mounting hole 38 (that is, the lower side). Further, the angles θ1 and θ2 of the slopes 54A and 54B are angles with respect to the depth direction (that is, the axial direction) of the mounting hole 38.

The male threaded portion 46 has a threaded thread 56 of a saw-toothed screw in which the angle θ4 of the slope 56B on the upper end side is smaller than the angle θ3 of the slope 56A on the lower end side so as to mesh with the female threaded portion 50 having the threaded thread 54 of the saw-toothed screw. Is preferable. Here, the angles θ3 and θ4 of the slopes 56A and 56B are angles with respect to the axial direction of the body 42.

By setting the shape of the thread teeth of the male threaded portion 46 and the female threaded portion 50 to the thread threads 54 and 56 of such a saw-toothed screw, it is possible to reduce the resistance to removing the hook after vulcanization and molding of the tire. In the embodiment shown in FIG. 6, other configurations and effects are the same as those in the embodiments shown in FIGS. 1 to 5, and the description thereof will be omitted.

In the above embodiment, it is not necessary to use the stud 40 having the same convex portion 44 shape for all the mounting holes 38 provided in the tire 10, and the convex portion 44 according to the purpose according to the position of the tread surface 24. A stud 40 having the shape of can be attached.

Further, the tire 10 may be sold with the stud 40 attached, or may be sold as a set with the stud 40 without the stud 40 attached, and the user can easily attach / detach the stud 40. Is.

Further, the stud 40 does not have to be mounted in all the mounting holes 38 provided in the tire 10, and the number of studs 40 to be mounted can be set according to the regulations of each country (regulation of the number of studs). For example, the number of mounting holes 38 provided in the tire 10 may be set to the maximum number of the regulations of a plurality of countries (for example, the whole world), and a predetermined number of studs 40 may be attached according to the regulations of the country in which the tire 10 is distributed. ..

Examples of the tire according to the present embodiment include tires for various vehicles such as tires for passenger cars, tires for heavy loads such as trucks, buses, and light trucks (for example, SUV cars and pickup trucks).

Although some embodiments have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and variations thereof are included in the scope of the invention described in the claims and the equivalent scope thereof, as are included in the scope and gist of the invention.

10 ... Tread part, 22 ... Tread rubber, 24 ... Tread surface, 26 ... Cap rubber layer, 28 ... Base rubber layer, 38 ... Mounting hole, 38B ... Bottom, 40 ... Stud, 42 ... Body, 44 ... Convex part, 46 ... Male threaded portion, 48 ... Inner peripheral surface of mounting hole, 50 ... Female threaded portion, 54 ... Thread thread, 54A ... Open side slope, 54B ... Bottom side slope

Claims (4)

A tire comprising a stud and a tread rubber having a mounting hole for which the stud is mounted.
The stud comprises a columnar body and a male threaded portion provided on the outer peripheral surface of the body.
The mounting hole is provided with a female thread on the inner peripheral surface.
A tire in which the stud is fixed to the mounting hole by screwing the male threaded portion into the female threaded portion. The tread rubber includes a cap rubber layer having a tread surface in contact with the road surface, and a base rubber layer made of rubber having a hardness higher than that of the cap rubber layer and arranged radially inside the cap rubber layer. ,
The mounting hole is formed by being recessed so that the bottom portion thereof enters the base rubber layer, and the female thread portion is provided at least on the bottom side in the depth direction of the mounting hole.
The tire according to claim 1. The tire according to claim 1 or 2, wherein the female thread portion has a thread of a sawtooth screw in which the angle of the slope on the bottom side is smaller than the angle of the slope on the opening side. The tire according to any one of claims 1 to 3, wherein the height of the thread of the female thread portion is formed to be larger than the height of the thread of the male thread portion.

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