Patent Description:
Some known pneumatic tires are provided with so-called sipes, which are cuts formed in a tread portion, in order to improve performance on ice and snow, which is running performance on snowy roads and frozen road surfaces, and wet performance, which is running performance on wet road surfaces, and the like. The pneumatic tires used on icy and snowy road surfaces include so-called pneumatic studded tires in which stud pins are disposed in a tread portion in order to further improve the performance on ice and snow. In a pneumatic studded tire, the stud pin is disposed by inserting the stud pin into a pin hole formed in the tread portion. In this way, in a pneumatic tire in which stud pins are disposed in the tread portion, a variety of ideas have been applied to ensure the performance on ice and snow. For example, the pneumatic tires described in Patent Documents <NUM> to <NUM> try to maintain the performance on ice and snow by suppressing the stud pins from coming off.

Here, the pin hole formed in the tread portion is formed by a mold pin included in a tire molding mold used for vulcanization molding of a pneumatic tire, and the sipe is formed by a sipe blade. In this way, when vulcanization molding of a pneumatic tire is performed using a tire molding mold including a mold pin and a sipe blade, twisting is likely to occur in a blade disposed at or near the mold pin when the tire is detached from the mold after the vulcanization molding is performed, and failures may easily occur in the blade due to twisting.

In other words, the tire molding mold is often divided into a predetermined number of sectors in the tire circumferential direction, and when the tire is detached from the mold after the vulcanization molding, the divided sectors are detached from the tire in different directions for respective sectors. On the other hand, the sipe blade is disposed in a direction in which the height direction is substantially parallel to the tire radial direction, and thus the direction in which the sectors are detached from the tire is often in a direction different from the height direction of the blade. In this case, the blade is pulled out in a direction different from the depth direction rather than the direction along the depth direction of the sipe formed by the blade, but the sipe is formed of a rubber member. And thus, due to the elastic deformation of the rubber, it is possible to pull out the blade from the sipe while suppressing the occurrence of a failure such as bending or folding in the blade pulled out in a direction different from the depth direction of the sipe.

However, in the blade disposed at or near the mold pin, the amount of rubber located between the blade and the mold pin during vulcanization molding is small, and there is a small number of members that elastically deform when the sector is detached from the tire. Thus, when the depth direction of the sipe formed by the blade differs from the direction in which the sector is detached from the tire, that is, the direction in which the blade is pulled out from the sipe, a large force acts on the blade from a sipe having a small amount of deformation due to elastic deformation. In this way, a force acts the blade in the direction of twisting the blade, and the blade is prone to failure such as bending or folding by this force.

Occurrence of such a blade failure can be suppressed by reducing the number of the pin holes, but in a case where the number of stud pins inserted into the pin holes is reduced, the performance on ice and snow may deteriorate as compared to a case where a large number of stud pins are inserted. And thus, it is very difficult to provide the durability of the sipe blade during manufacturing of pneumatic tires and the performance on ice and snow of pneumatic tires in a compatible manner.

Patent document <CIT> discloses similar features to the respective preambles of independent claims <NUM> and <NUM>.

In light of the foregoing, an object of the present invention is to provide a pneumatic tire and a tire molding mold that can provide the durability of sipe blades and the performance on ice and snow in a compatible manner.

In order to solve the problems described above and achieve the object, a pneumatic tire according to the present invention includes, a plurality of sipes disposed in a land portion formed in a tread portion, and a plurality of pin holes for stud pins disposed in the land portion, the sipes being disposed at positions where a distance Ds from the pin hole and a diameter Dp of the pin hole satisfy a relationship of (Ds/Dp) ≥ <NUM>, the sipe, among the plurality of sipes, in which the distance Ds from the pin hole and the diameter Dp of the pin hole satisfy a relationship of (Ds/Dp) ≤ <NUM> being defined as a pin hole neighboring sipe, the sipe of which the distance Ds from the pin hole is the smallest, among the sipes in which the distance Ds from the pin hole and the diameter Dp of the pin hole satisfy a relationship of (Ds/Dp) > <NUM>, being defined as a normal sipe, and the pin hole neighboring sipe being formed in a high rigidity shape having higher rigidity than the normal sipe.

In the pneumatic tire described above, preferably a maximum depth of the pin hole neighboring sipe is shallower than a maximum depth of the normal sipe.

In the pneumatic tire described above, preferably, a ratio of a maximum depth H1 of the pin hole neighboring sipe to a maximum depth H2 of the normal sipe is in a range of <NUM> ≤ (H1/H2) ≤ <NUM>.

In the pneumatic tire described above, preferably, a ratio of a maximum width W1 of the pin hole neighboring sipe to a maximum width W2 of the normal sipe is in a range of <NUM> ≤ (W1/W2) ≤ <NUM>.

In the pneumatic tire described above, preferably, the pin hole neighboring sipe is formed oscillating in a width direction in a depth direction.

In the pneumatic tire described above, preferably, only the pin hole neighboring sipe, in which the number of bend points is less than three in a length direction of the pin hole neighboring sipe among the plurality of pin hole neighboring sipes, is formed in the high rigidity shape.

In the pneumatic tire described above, preferably, the pneumatic tire being molded by a tire molding mold including a plurality of sectors divided in a tire circumferential direction, and only the pin hole neighboring sipe, among the plurality of pin hole neighboring sipes, located at or near a position corresponding to a division position between the sectors of the tire molding mold in the land portion, being formed in the high rigidity shape.

In order to solve the problems described above and achieve the object, a tire molding mold according to the present invention includes, a plurality of sectors divided in a tire circumferential direction, a plurality of sipe blades disposed on a tread molding surface of the sectors, and a plurality of mold pins disposed on the tread molding surface, the sipe blades being disposed at positions where a distance Dsm from the mold pin and a diameter Dpm of the mold pin satisfy a relationship of (Dsm/Dpm) ≥ <NUM>, the sipe blade, among the plurality of sipe blades, in which the distance Dsm from the mold pin and the diameter Dpm of the mold pin satisfy a relationship of (Dsm/Dpm) ≤ <NUM>, being defined as a pin neighboring blade, the sipe blade of which the distance Dsm from the mold pin is the smallest, among the sipe blades in which the distance Dsm of the mold pin and the diameter Dpm of the mold pin satisfy a relationship of (Dsm/Dpm) > <NUM>, being defined as a normal blade, and the pin neighboring blade being formed in a high rigidity shape having higher rigidity than the normal blade.

The pneumatic tire and the tire molding mold according the present invention can provide the durability of sipe blades and the performance on ice and snow in a compatible manner.

Pneumatic tires and tire molding molds according to embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited by the embodiment. Constituents of the following embodiments include elements that are essentially identical or that can be substituted or easily conceived of by a person skilled in the art.

In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not illustrated) of a pneumatic tire <NUM>, the inner side in the tire radial direction refers to the side facing the rotation axis in the tire radial direction, and the outer side in the tire radial direction refers to the side away from the rotation axis in the tire radial direction. Moreover, the tire circumferential direction refers to the circumferential direction with the rotation axis as the center axis. Additionally, the tire width direction refers to a direction parallel with the rotation axis, the inner side in the tire width direction refers to a side toward the tire equatorial plane (tire equator line) CL in the tire width direction, and the outer side in the tire width direction refers to a side away from the tire equatorial plane CL in the tire width direction. The tire equatorial plane CL is a plane that is orthogonal to the rotation axis of the pneumatic tire <NUM> and passes through the center of the tire width of the pneumatic tire <NUM>, and in the tire equatorial plane CL, the center line in the tire width direction, which is the center position of the pneumatic tire <NUM> in the tire width direction, coincides with the position in the tire width direction. The tire width is the width in the tire width direction between portions located on the outermost sides in the tire width direction, or in other words, the distance between the portions that are the most distant from the tire equatorial plane CL in the tire width direction. "Tire equator line" refers to a line along the tire circumferential direction of the pneumatic tire <NUM> that lies on the tire equatorial plane CL.

<FIG> is a plan view of a road contact surface <NUM> of a tread portion <NUM> of the pneumatic tire <NUM> according to an embodiment. The pneumatic tire <NUM> illustrated in <FIG> includes the tread portion <NUM> disposed at the outermost portion of the pneumatic tire <NUM> in the tire radial direction. The surface of the tread portion <NUM>, in other words, a portion that comes into contact with a road surface when a vehicle (not illustrated) equipped with the pneumatic tire <NUM> travels is formed as the road contact surface <NUM>. A plurality of grooves <NUM> are formed in the road contact surface <NUM>, and a plurality of land portions <NUM> are defined by the plurality of grooves <NUM>. As the grooves <NUM>, for example, a plurality of circumferential grooves <NUM> extending in the tire circumferential direction and a plurality of lug grooves <NUM> extending in the tire width direction are formed. A tread pattern is formed by these grooves <NUM> and land portions <NUM> in the road contact surface <NUM>. In the present embodiment, the lug grooves <NUM> are inclined in the tire circumferential direction while extending in the tire width direction, and the circumferential grooves <NUM> are formed between adjacent lug grooves <NUM> in the tire circumferential direction. The land portions <NUM> are formed in block shape by the circumferential grooves <NUM> and the lug grooves <NUM>.

Additionally, a plurality of sipes <NUM> are formed in the road contact surface <NUM>. The sipes <NUM> described herein are formed in a narrow groove shape in the road contact surface <NUM>. In the sipes <NUM>, when the pneumatic tire <NUM> is mounted on a regular rim, inflated to a regular internal pressure, and in an unloaded state, wall surfaces constituting the narrow groove do not contact one another, whereas in a case where the narrow groove is located in a portion of the ground contact surface formed on a flat plate in response to application of a load on the flat plate in the vertical direction or in a case where the land portion <NUM> provided with the narrow groove flexes, the wall surfaces constituting the narrow groove or at least parts of portions provided on the wall surface contact one another due to deformation of the land portion <NUM>. Here, "regular rim" refers to a "standard rim" defined by JATMA, a "Design Rim" defined by TRA, or a "Measuring Rim" defined by ETRTO. Moreover, a regular internal pressure refers to a "maximum air pressure" defined by JATMA, the maximum value in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" defined by TRA, or "INFLATION PRESSURES" defined by ETRTO. In the present embodiment, the width of the sipe <NUM> is within a range of <NUM> or more and <NUM> or less, and a depth thereof is within a range of <NUM> or more and <NUM> or less.

The sipes <NUM> are formed extending in the tire width direction at a predetermined depth, and are disposed in each of the land portions <NUM> defined by the grooves <NUM>. Some of the sipes <NUM> bend in the tire circumferential direction while extending in the tire width direction and the sipes <NUM> vary in form.

Additionally, a plurality of pin holes <NUM> which are holes for stud pins (not illustrated) are disposed in the road contact surface <NUM> of the tread portion <NUM>. The pin hole <NUM> is formed as a hole that opens to the road contact surface <NUM> in a substantially circular shape and extends in the tire radial direction. A metallic stud pin is inserted into the pin hole <NUM> and thus the stud pin can be disposed in the road contact surface <NUM>. Note that, the portion of the stud pin inserted into the pin hole <NUM> has a different diameter depending on the position of the stud pin in the axial direction and thus the stud pin does not easily come out of the pin hole <NUM> after it is inserted into the pin hole <NUM>. In line with this, the pin hole <NUM> has a different diameter depending on the depth direction of the pin hole <NUM>.

<FIG> is a detailed view of the portion A of <FIG>. A mark portion <NUM> is formed around the pin hole <NUM> such that the position of the pin hole <NUM> is easily identified. The mark portion <NUM> is formed around the pin hole <NUM> in the road contact surface <NUM> as an unevenness pattern. The mark portion <NUM> is formed in a substantially circular shape concentric with the pin hole <NUM>, whose diameter is larger than the diameter of the pin hole <NUM>. In addition, the mark portion <NUM> has a pattern that makes the pin hole <NUM> more noticeable. In the present embodiment, the pattern is formed in a substantially fan-shaped shape in the inner side of the circle of the mark portion <NUM>, and is provided at two locations that are point-symmetrical about the center of the pin hole <NUM>.

The mark portion <NUM> formed as the unevenness pattern has an unevenness amount within a range of <NUM> or less with respect to the surface of the road contact surface <NUM> where the unevenness pattern is not formed. In this case, the unevenness may be formed as protrusions from the road contact surface <NUM>, or may be formed as recesses.

Some of the plurality of sipes <NUM> formed in the road contact surface <NUM> are also disposed near the pin hole <NUM>. The sipe <NUM> disposed near the pin hole <NUM> is disposed on the outer side of the mark portion <NUM> without entering the inner side of the mark portion <NUM> formed in a substantially circular shape.

<FIG> is a detailed view of the portion B of <FIG>. <FIG> shows the pin hole <NUM> and the mark portion <NUM> in a simplified manner so that the positional relationship between the sipe <NUM> and the pin hole <NUM> can be easily understood. The plurality of sipes <NUM> disposed in the road contact surface <NUM> are disposed at positions where the distance Ds from the pin hole <NUM> and the diameter Dp of the pin hole <NUM> satisfy a relationship of (Ds/Dp) ≥ <NUM>. That is, the sipe <NUM> is not disposed within a range from the pin hole <NUM> that is <NUM> times the diameter Dp of the pin hole <NUM>, and the region within this range is a region Ns where the sipe <NUM> is not present. Specifically, the region Ns where the sipe <NUM> is not present is a region in which a groove or an unevenness having a depth of <NUM> or more including the sipe <NUM> is not present.

Note that in this case, the diameter Dp of the pin hole <NUM> is the diameter of the opening of the pin hole <NUM> that opens in a substantially circular shape with respect to the road contact surface <NUM>. Additionally, the region Ns where the sipe <NUM> is not present is preferably within a range of <NUM> or more and <NUM> or less from the center of the pin hole <NUM>. In the present embodiment, the radius of the mark portion <NUM> is larger than the radius of the region Ns where the sipe <NUM> is not present.

In addition, a pin hole neighboring sipe <NUM> which is the sipe <NUM> disposed near the pin hole <NUM> among the plurality of sipes <NUM> is formed in a high rigidity shape having higher rigidity than a normal sipe <NUM> which is the sipe <NUM> other than the pin hole neighboring sipe <NUM> disposed near the pin hole neighboring sipe <NUM>.

The pin hole neighboring sipe <NUM> here is the sipe <NUM> in which the distance Ds from the pin hole <NUM> and the diameter Dp of the pin hole <NUM> satisfy a relationship of (Ds/Dp) ≤ <NUM> among the plurality of sipes <NUM>. That is, the pin hole neighboring sipe <NUM> is the sipe <NUM> in which the distance Ds from the pin hole <NUM>, that is, the distance Ds of the portion closest to the pin hole <NUM>, and the diameter Dp of the pin hole <NUM> satisfy a relationship of <NUM> ≤ (Ds/Dp) ≤ <NUM>. Specifically, in the pin hole neighboring sipe <NUM>, the distance Ds from the pin hole <NUM> of the end portion 21a in the length direction and the diameter Dp of the pin hole <NUM> satisfy a relationship of <NUM> ≤ (Ds/Dp) ≤ <NUM>. Note that the number of pin hole neighboring sipes <NUM> corresponding to one pin hole <NUM> may be <NUM>, or may be one or plural.

In addition, the normal sipe <NUM> is the sipe <NUM> of which the distance Ds from the pin hole <NUM> is the smallest among the sipes <NUM> in which the distance Ds from the pin hole <NUM> and the diameter Dp of the pin hole <NUM> satisfy a relationship of (Ds/Dp) > <NUM>. That is, the normal sipe <NUM> is the sipe <NUM> of which the distance Ds from the pin hole <NUM> is the smallest among the sipes <NUM> other than the sipes <NUM> satisfying the definitions of the pin hole neighboring sipe <NUM>. The pin hole neighboring sipe <NUM> is formed in a high rigidity shape having higher rigidity than the normal sipe <NUM> defined in this way.

<FIG> is a cross-sectional view taken along the line C-C in <FIG>. <FIG> is a cross-sectional view taken along the line E-E in <FIG>. The pin hole neighboring sipe <NUM> has a maximum depth H1 that is shallower than the maximum depth H2 of the normal sipe <NUM>. As a result, the pin hole neighboring sipe <NUM> has rigidity higher than that of the normal sipe <NUM>. That is, the pin hole neighboring sipe <NUM> has the maximum depth H1 shallower than the maximum depth H2 of the normal sipe <NUM>. And thus, the volume of the space where the sipe <NUM> is formed, that is, the volume of the portion where the rubber constituting the land portion <NUM> is not disposed, is small, and the proportion of the disposed rubber is large, and thus, the rigidity is high. Specifically, the ratio of the maximum depth H1 of the pin hole neighboring sipe <NUM> to the maximum depth H2 of the normal sipe <NUM> is in the range of <NUM> ≤ (H1/H2) ≤ <NUM>.

Now, a tire molding mold <NUM> according to the embodiment will be described. Note that in the following description, the tire radial direction of the pneumatic tire <NUM> will be described as the tire radial direction in the tire molding mold <NUM> and that the tire width direction of the pneumatic tire <NUM> will be described as the tire width direction of the tire molding mold <NUM> and that the tire circumferential direction of the pneumatic tire <NUM> will be described as the tire circumferential direction in the tire molding mold <NUM>.

<FIG> is an explanatory diagram of the tire molding mold <NUM> for manufacturing the pneumatic tire <NUM> according to an embodiment. As illustrated in <FIG>, the tire molding mold <NUM> is configured as a so-called sector mold corresponding to a divided tire molding mold <NUM>, and has an annular structure in which a plurality of sectors <NUM> separated from one another in the tire circumferential direction are connected to one another. Note that in <FIG>, the tire molding mold <NUM> is illustrated in the form of an eight-division structure including eight sectors <NUM>, but the number of divisions of the tire molding mold <NUM> is not limited to eight.

One sector <NUM> includes a plurality of pieces <NUM> for forming the tread portion <NUM> of the pneumatic tire <NUM> corresponding to a product, and a back block <NUM> in which the pieces <NUM> are mounted adjacent to one another. One piece <NUM> corresponds to a portion of the tread pattern formed in the tread portion <NUM> of the pneumatic tire <NUM>, and includes a tread molding surface <NUM> for forming a part of the tread pattern. One sector <NUM> includes a plurality of pieces <NUM> in the tire circumferential direction and the tire width direction, respectively (not illustrated), and the plurality of pieces <NUM> are assembled to constitute the tread molding surface <NUM> of one sector <NUM>. In other words, the piece <NUM> of one sector <NUM> is divided into a plurality of pieces <NUM>.

In the back block <NUM>, a plurality of pieces <NUM> are mounted and held in a predetermined arrangement. One sector <NUM> is thus configured.

The tire molding mold <NUM> is configured by using a plurality of the sectors <NUM> configured as described above and connecting the plurality of sectors <NUM> in an annular shape. In the tire molding mold <NUM>, the plurality of sectors <NUM> are connected together in an annular shape to assemble the tread molding surfaces <NUM> of the sectors <NUM>, forming the tread molding surface <NUM> of the entire tread pattern.

<FIG> is a view in the direction of arrow F-F in <FIG>, and is an explanatory diagram of a state in which the sectors <NUM> are connected together. In the tread molding surface <NUM> in each sector <NUM>, a plurality of circumferential groove forming bones <NUM> are disposed that form the circumferential grooves <NUM> in the tread portion <NUM> of the pneumatic tire <NUM>, a plurality of lug groove forming bones <NUM> are disposed that form the lug grooves <NUM>, a plurality of sipe blades <NUM> that form the sipes <NUM>, and a plurality of mold pins <NUM> that form the pin holes <NUM> are disposed. In this regard, the circumferential groove forming bones <NUM> and the lug groove forming bones <NUM> are formed in a rib-like shape protruding from the tread molding surface <NUM>, and the sipe blades <NUM> are formed as plate-like members formed from a metal material. For example, stainless steel is used as the metal material that forms the sipe blade <NUM>. Additionally, the sipe blades <NUM> are disposed on the tread molding surface <NUM> such that the sipe blades <NUM> are identical in number to the sipes <NUM> formed in the tread portion <NUM>. The sipe blades <NUM> are respectively disposed at positions in the tread molding surface <NUM> corresponding to positions in the tread portion <NUM> where the sipes <NUM> are disposed.

Additionally, the mold pin <NUM> is formed in a substantially cylindrical shape protruding from the tread molding surface <NUM> such that the mold pin <NUM> is formed in a substantially cylindrical shape with the diameter being different depending on the position in the axial direction of the cylinder. Additionally, the mold pins <NUM> are disposed on the tread molding surface <NUM> such that the sipe blades <NUM> are identical in number to the pin holes <NUM> formed in the tread portion <NUM>. The mold pins <NUM> are respectively disposed at positions in the tread molding surface <NUM> corresponding to positions in the tread portion <NUM> where the pin holes <NUM> are disposed.

A mark forming portion <NUM> that forms the mark portion <NUM> in the road contact surface <NUM> is formed on the base of the mold pin <NUM> in the tread molding surface <NUM>. The mark forming portion <NUM> is formed as an unevenness pattern around the mold pin <NUM> in the tread molding surface <NUM>. Some of the plurality of sipe blades <NUM> disposed in the tread molding surface <NUM> are also disposed near the mold pin <NUM>. The sipe blade <NUM> disposed near the mold pin <NUM> is disposed on the outer side of the mark forming portion <NUM> without entering the inner side of the mark forming portion <NUM> formed in a substantially circular shape.

<FIG> is a detailed view of the portion J in <FIG>. <FIG> illustrates the mold pin <NUM> and the mark forming portion <NUM> in a simplified manner so that the positional relationship between the sipe blade <NUM> and the mold pin <NUM> can be easily understood. The plurality of sipe blades <NUM> disposed in the tread molding surface <NUM> are disposed at positions where the distance Dsm from the mold pin <NUM> and the diameter Dpm of the mold pin <NUM> satisfy a relationship of (Dsm/Dpm) ≥ <NUM>. That is, the sipe blade <NUM> is not disposed within a range from the mold pin <NUM> that is <NUM> times the diameter Dpm of the mold pin <NUM>, and the region within this range is the region Nb where the sipe blade <NUM> is not present. Note that in this case, the diameter Dpm of the mold pin <NUM> is the diameter at the base of the mold pin <NUM> that is disposed in a substantially circular shape with respect to the tread molding surface <NUM>.

In addition, a pin neighboring blade <NUM> which is the sipe blade <NUM> disposed at or near the mold pin <NUM> among the plurality of sipe blades <NUM> is formed in a high rigidity shape having higher rigidity than a normal blade <NUM> which is the sipe blade <NUM> other than the pin neighboring blade <NUM> disposed at or near the pin neighboring blade <NUM>.

The pin neighboring blade <NUM> here is the sipe blade <NUM> in which the distance Dsm from the mold pin <NUM> and the diameter Dpm of the mold pin <NUM> satisfy a relationship of (Dsm/Dpm) ≤ <NUM> among the plurality of sipe blades <NUM>. That is, the pin neighboring blade <NUM> is the sipe blade <NUM> in which that the distance Dsm from the mold pin <NUM>, that is, the distance Dsm of the portion closest to the mold pin <NUM>, and the diameter Dpm of the mold pin <NUM> satisfy a relationship of <NUM> ≤ (Dsm/Dpm) ≤ <NUM>. Specifically, in the pin neighboring blade <NUM>, the distance Dsm from the mold pin <NUM> of the end portion 121a in the length direction and the diameter Dpm of the mold pin <NUM> satisfy a relationship of <NUM> ≤ (Dsm/Dpm) ≤ <NUM>. Note that the number of pin neighboring blades <NUM> corresponding to one mold pin <NUM> may be <NUM>, or may be one or a plural.

In addition, the normal blade <NUM> is the sipe blade <NUM> of which the distance Dsm from the mold pin <NUM> is the smallest among the sipe blades <NUM> in which the distance Dsm from the mold pin <NUM> and the diameter Dpm of the mold pin <NUM> satisfy a relationship of (Dsm/Dpm) > <NUM>. That is, the normal blade <NUM> is the sipe blade <NUM> of which the distance Dsm from the mold pin <NUM> is the smallest among the sipe blades <NUM> other than the sipe blades <NUM> satisfying the definitions of the pin neighboring blade <NUM>. The pin neighboring blade <NUM> is formed in a high rigidity shape having higher rigidity than the normal blade <NUM> defined in this way.

<FIG> is a view in the direction of arrow K-K of <FIG>. <FIG> is a view in the direction of arrow M-M in <FIG>. The pin neighboring blade <NUM> has a maximum height H1m lower than the maximum height H2m of the normal blade <NUM>. As a result, the pin neighboring blade <NUM> has rigidity higher than the rigidity of the normal blade <NUM>. Specifically, the pin neighboring blade <NUM> is configured such that a ratio of the maximum height H1m of the pin neighboring blade <NUM> to the maximum height H2m of the normal blade <NUM> is in the range of <NUM> ≤ (H1m/H2m) ≤ <NUM>.

Note that in the present embodiment, the height of the sipe blade <NUM> in the tire radial direction from the tread molding surface <NUM> is in the range of <NUM> or more and <NUM> or less. Thus, both the maximum height H1m of the pin neighboring blade <NUM> and the maximum height H2m of the normal blade <NUM> are in the range of <NUM> or more and <NUM> or less. Moreover, the thickness of the sipe blade <NUM> is in the range of <NUM> or more and <NUM> or less.

Now, a manufacturing method for the pneumatic tire <NUM> using the tire molding mold <NUM> according to an embodiment will be described. <FIG> is an explanatory diagram illustrating a tire manufacturing method using the tire molding mold <NUM> illustrated in <FIG>. <FIG> illustrates an axial cross-sectional view of the mold support device <NUM> including the tire molding mold <NUM> illustrated in <FIG>. The pneumatic tire <NUM> according to the present embodiment is manufactured in accordance with manufacturing steps described below.

First, various rubber members (not illustrated) that constitute the pneumatic tire <NUM>, and members such as carcass plies (not illustrated) and belt plies (not illustrated) are applied to a molding machine to form a green tire G. Then, the green tire G is mounted on the mold support device <NUM> (see <FIG>).

In <FIG>, the mold support device <NUM> includes a support plate <NUM>, an outer ring <NUM>, a segment <NUM>, a top plate <NUM> and a base plate <NUM>, an upper side mold <NUM> and a lower side mold <NUM>, and the tire molding mold <NUM>. The support plate <NUM> has a disc shape and is disposed with the flat surface thereof to be horizontal. The outer ring <NUM> is an annular structure including a tapered surface <NUM> on an inner side in the radial direction, and is installed and suspended from a lower portion of an outer peripheral edge of the support plate <NUM>. The segment <NUM> is a divisible annular structure corresponding to the sectors <NUM> of the tire molding mold <NUM> and is inserted into the outer ring <NUM> and disposed slidably in the axial direction relative to the tapered surface <NUM> of the outer ring <NUM>. The top plate <NUM> is installed movably in the axial direction inside the outer ring <NUM> and between the segment <NUM> and the support plate <NUM>. The base plate <NUM> is disposed below the support plate <NUM> and at a position opposite the support plate <NUM> in the axial direction.

The upper side mold <NUM> and the lower side mold <NUM> include molding surfaces with side profiles corresponding to both side surfaces of the pneumatic tire <NUM> in the tire width direction. Additionally, the upper side mold <NUM> and the lower side mold <NUM> are disposed such that the upper side mold <NUM> is attached to the lower surface side of the top plate <NUM>, the lower side mold <NUM> is attached to the upper surface side of the base plate <NUM>, and the molding surface of the upper side mold <NUM> faces the molding surface of the lower side mold <NUM>. As described above, the tire molding mold <NUM> has a divisible annular structure (see <FIG>) with the tread molding surface <NUM> enabling a tread profile to be formed. Additionally, each of the sectors <NUM> of the tire molding mold <NUM> are attached to the inner circumferential surfaces of the corresponding segments <NUM>, and the tire molding mold <NUM> is disposed such that the tread molding surface <NUM> faces the side where the molding surfaces of the upper side mold <NUM> and the lower side mold <NUM> are located.

Then, the green tire G is mounted between the molding surface of the tire molding mold <NUM> and the molding surfaces of the upper side mold <NUM> and the lower side mold <NUM>. At this time, the support plate <NUM> moves downward in the axial direction to move the outer ring <NUM> downward in the axial direction along with the support plate <NUM>, and the tapered surface <NUM> of the outer ring <NUM> pushes the segments <NUM> radially inward. Then, the tire molding mold <NUM> is contracted in diameter to annularly connect the molding surfaces of the sectors <NUM> of the tire molding mold <NUM>, and the entire molding surface of the tire molding mold <NUM> is connected to the molding surface of the lower side mold <NUM>. Additionally, the top plate <NUM> moves downward in the axial direction to lower the upper side mold <NUM>, reducing the distance between the upper side mold <NUM> and the lower side mold <NUM>. Then, the entire molding surface of the tire molding mold <NUM> is connected to the molding surface of the upper side mold <NUM>. Accordingly, the green tire G is surrounded and held by the molding surface of the tire molding mold <NUM>, the molding surface of the upper side mold <NUM>, and the molding surface of the lower side mold <NUM>.

Then, the green tire G corresponding to an unvulcanized tire is subjected to vulcanization molding. Specifically, the tire molding mold <NUM> is heated, and the green tire G is expanded radially outward by a pressurizing device (not illustrated) and pressed against the tread molding surface <NUM> of the tire molding mold <NUM>. Then, the green tire G is heated, and rubber molecules and sulfur molecules in the tread portion <NUM> are bonded together, leading to vulcanization. Then, the tread molding surface <NUM> of the tire molding mold <NUM> is transferred to the green tire G, forming the tread pattern in the tread portion <NUM>.

Subsequently, the tire after vulcanization molding is acquired as a product tire corresponding to the pneumatic tire <NUM> to be provided as a product. At this time, the support plate <NUM> and the top plate <NUM> move upward in the axial direction to space the tire molding mold <NUM>, the upper side mold <NUM>, and the lower side mold <NUM> apart from one another, opening the mold support device <NUM>. In response to opening of the mold support device <NUM>, the tire detaches the tire molding mold <NUM> from the mold support device <NUM> with the tire subjected to vulcanization molding.

<FIG> is an explanatory diagram illustrating a state before the tire molding mold <NUM> is detached from the pneumatic tire <NUM> after vulcanization molding. During vulcanization molding of the pneumatic tire <NUM> using the tire molding mold <NUM>, the tread portion <NUM> is formed by the tire molding mold <NUM>. Thus, immediately after vulcanization molding is performed, the tire molding mold <NUM> is attached to the tread portion <NUM> of the pneumatic tire <NUM> (see <FIG>). Specifically, the plurality of sectors <NUM> of the tire molding mold <NUM> are connected in an annular shape, and the tire molding mold <NUM> is attached to the tread portion <NUM> of the pneumatic tire <NUM> immediately after vulcanization molding is performed. In response to completion of the vulcanization molding of the pneumatic tire <NUM> and detachment, by the tire, of the tire molding mold <NUM> from the mold support device <NUM>, the plurality of sectors <NUM> connected together in an annular shape and attached to the tread portion <NUM> of the pneumatic tire <NUM> are detached from the pneumatic tire <NUM>. Accordingly, the tire molding mold <NUM> is detached from the pneumatic tire <NUM>.

<FIG> is an explanatory diagram illustrating a state in which the tire molding mold <NUM> is detached from the pneumatic tire <NUM> after vulcanization molding. In a case that the plurality of sectors <NUM> are detached from the pneumatic tire <NUM>, the sectors <NUM> are moved toward the outer side in the tire radial direction and separated from the tread portion <NUM> of the pneumatic tire <NUM>. Accordingly, the tire molding mold <NUM> is detached from the pneumatic tire <NUM>. In this case, during vulcanization molding of the pneumatic tire <NUM>, the plurality of sipe blades <NUM> disposed on the tread molding surfaces <NUM> of the sectors <NUM> of the tire molding mold <NUM> form a plurality of sipes <NUM> in the road contact surface <NUM> of the tread portion <NUM>, and the plurality of mold pins <NUM> disposed on the tread forming surface <NUM> form a plurality of pin holes <NUM> in the road contact surface <NUM> of the tread portion <NUM>. In response to detachment of the sectors <NUM> of the tire molding mold <NUM> from the pneumatic tire <NUM> by moving the sectors <NUM> toward the outer side in the tire radial direction, the plurality of sipe blades <NUM> and the plurality of mold pins <NUM> disposed on the sectors <NUM> are extracted from the sipes <NUM> and the pin holes <NUM> formed in the tread portion <NUM> of the pneumatic tire <NUM>.

In this regard, the sipe blades <NUM> and the mold pins <NUM> disposed on the tread molding surfaces <NUM> of the sector <NUM> extend from the tread molding surfaces <NUM> generally toward the inner side in the tire radial direction. On the other hand, in a case of detaching the sectors <NUM> from the pneumatic tire <NUM>, the sectors <NUM> are moved toward the outer side in the tire radial direction. Thus, in the sipe blade <NUM> and the mold pin <NUM> disposed in the tread molding surface <NUM>, differences between the direction of extending from the tread molding surface <NUM> and the movement direction when the sector <NUM> is detached from the pneumatic tire <NUM> are different depending on the position in the tire circumferential direction on the tread molding surface <NUM> of the sector <NUM>. For example, the sipe blade <NUM>, among the plurality of sipe blades <NUM> disposed on one sector <NUM>, disposed in a central region of the sector <NUM> in the tire circumferential direction has the direction in which the sipe blade <NUM> extends from the tread molding surface <NUM> being similar to the direction in which the sector <NUM> is moved.

In contrast, for the sipe blade <NUM>, among the plurality of sipe blades <NUM> disposed on one sector <NUM>, disposed at or near the division position 101a between the sectors <NUM> has the direction in which the sipe blade <NUM> extends from the tread molding surface <NUM> being inclined with respect to the direction in which the sector <NUM> is moved. In other words, in a case where the sectors <NUM> are detached from the pneumatic tire <NUM>, one sector <NUM> is integrally moved, and thus, the direction in which the sector <NUM> is moved corresponds, even at or near the division position 101a between the sectors <NUM>, to the identical direction as the direction in which a position in a central region of the sector <NUM> in the tire circumferential direction is moved toward the outer side in the tire radial direction. Thus, the direction of movement of the division position 101a between the sectors <NUM> during detachment of the sectors <NUM> from the pneumatic tire <NUM> differs from the tire radial direction, and thus, the direction in which the sipe blade <NUM> disposed at or near the division position 101a between the sectors <NUM> moves during detachment of the sectors <NUM> from the pneumatic tire <NUM> differs from the direction in which the sipe blades <NUM> extends from the tread molding surface <NUM>.

Similarly, in the plurality of sipe blades <NUM> disposed in the tread molding surface <NUM>, differences between the direction of extending from the tread molding surface <NUM> and the movement direction when the sector <NUM> is detached from the pneumatic tire <NUM> are different depending on the position in the tire circumferential direction on the tread molding surface <NUM> of the sector <NUM>. Similarly, in the mold pins <NUM>, differences between the direction of extending from the tread molding surface <NUM> and the movement direction when the sector <NUM> is detached from the pneumatic tire <NUM> are different depending on the position in the tire circumferential direction on the tread molding surface <NUM> of the sector <NUM>.

In the sipe blade <NUM> and the mold pin <NUM>, the differences between the direction of extending from the tread molding surface <NUM> and the movement direction of the sipe blade <NUM> and the mold pin <NUM> when the sector <NUM> is detached from the pneumatic tire <NUM> are different depending on the position in the tire circumferential direction on the tread molding surface <NUM> of the sector <NUM>. However, the tread portion <NUM> of the pneumatic tire <NUM> is formed of a rubber member having elasticity. Thus, even when there are differences between the direction of extending from the tread molding surface <NUM> and the movement direction when the sector <NUM> is detached from the pneumatic tire <NUM>, the rubber member around the sipe <NUM> formed by the sipe blade <NUM> and the pin hole <NUM> formed by the mold pin <NUM> elastically deforms, and thus the sipe blade <NUM> and the mold pin <NUM> can be pulled out of the sipe <NUM> and the pin hole <NUM>.

That is, for example, when the movement direction of the sipe blade <NUM> and the depth direction of the sipe <NUM> formed by the sipe blade <NUM> are different, the force when moving the sector <NUM> acts on the sipe blade <NUM> in a direction different from the depth direction of the sipe <NUM>. In this case, a reaction force from the sipe <NUM> acts on the sipe blade <NUM>, but the sipe <NUM> is formed of a rubber member. And thus, the sipe blade <NUM> can move in a direction different from the depth direction of the sipe <NUM> due to the elastic deformation of the rubber member. Even when the movement direction of the sipe blade <NUM> is different from the depth direction of the sipe <NUM>, the rubber member elastically deforms and thus the sipe blade <NUM> can be pulled out of the sipe <NUM>.

On the other hand, when the distance between the sipe blade <NUM> and the mold pin <NUM> is small, the amount of the rubber member present between the sipe blade <NUM> and the mold pin <NUM> is reduced when the sector <NUM> is detached from the pneumatic tire <NUM>. That is, when the distance between the plurality of pin holes <NUM> and the plurality of sipes <NUM> disposed in the land portion <NUM> of the pneumatic tire <NUM> is small, the amount of the rubber member present between the sipe <NUM> and the pin hole <NUM> is reduced. In this case, when the depth direction of the sipe <NUM> formed by the sipe blade <NUM> and the movement direction of the sipe blade <NUM> when the sector <NUM> is detached from the pneumatic tire <NUM> are different, the amount of the member that is elastically deformed around the sipe blade <NUM> is reduced.

Thus, when the sipe blade <NUM> is pulled out of the sipe <NUM> into which the sipe blade <NUM> is inserted, a large reaction force from the rubber member forming the sipe <NUM> acts on the sipe blade <NUM>. In a case of detachment of the sectors <NUM> from the pneumatic tire <NUM>, a reaction force from the rubber member forming the sipes <NUM> acts on the sipe blade <NUM> at a close distance from the mold pin <NUM>, and is likely to cause failure such as bending or folding of the sipe blade <NUM> by the reaction force.

In contrast, in the pneumatic tire <NUM> according to the present embodiment, the pin hole neighboring sipe <NUM> in which the distance Ds from the pin hole <NUM> and the diameter Dp of the pin hole <NUM> satisfy a relationship of (Ds/Dp) ≤ <NUM> is formed in a high rigidity shape having higher rigidity than the normal sipe <NUM> of which the distance Ds from the pin hole <NUM> is the smallest among the sipes <NUM> in which the distance Ds from the pin hole <NUM> and the diameter Dp from the pin hole <NUM> satisfy a relationship of (Ds/Dp) > <NUM>. That is, the pin hole neighboring sipe <NUM> has a high rigidity shape in which the rigidity of the entire groove formed by the wall surface and the bottom portion that forms the sipe <NUM> is higher than that of the normal sipe. In line with this, the sipe blade <NUM> that forms the pin hole neighboring sipe <NUM> has a high rigidity shape having higher rigidity than the sipe blade <NUM> that forms the normal sipe <NUM>. Thus, when the sipe blade <NUM> that forms the pin hole neighboring sipe <NUM> in which the amount of the rubber member present between the pin hole <NUM> and the pin hole neighboring sipe <NUM> is small due to the small distance Ds from the pin hole <NUM> is pulled out of the pin hole neighboring sipe <NUM>, even when a large reaction force from the rubber member forming the sipe <NUM> acts on the sipe blade <NUM>, the occurrence of failures such as bending of the sipe blade <NUM> can be suppressed.

Additionally, since the sipes <NUM> are disposed at positions where the distance Ds from the pin hole <NUM> and the diameter Dp of the pin hole <NUM> satisfy a relationship of (Ds/Dp) ≥ <NUM>, it is possible to suppress the distance Ds from the pin hole <NUM> of any sipe <NUM> from becoming too small. As a result, it is possible to suppress the amount of the rubber member disposed between the sipe <NUM> and the pin hole <NUM> from becoming too small. Moreover, it is possible to suppress the occurrence of failures such as bending in the sipe blade <NUM> due to a reaction force acting from the rubber member forming the sipe <NUM> when the sipe blade <NUM> is pulled out of the sipe <NUM>.

In addition, since the pin hole neighboring sipe <NUM> is formed in a high rigidity shape, and thus the sipes <NUM> can be disposed at or near the pin holes <NUM> while suppressing the occurrence of failures in the sipe blade <NUM>, it is possible to dispose more sipes <NUM>. Thus, the edge effect when traveling on snow-covered road surfaces or icy road surfaces can be improved. The state of the pneumatic tire <NUM> when the pneumatic tire <NUM> is mounted on a vehicle and the vehicle travels will be described. When the pneumatic tire <NUM> is mounted on a vehicle, the pneumatic tire <NUM> is mounted on a rim wheel, inflated with air, and then mounted on the vehicle in an inflated state. When the vehicle on which the pneumatic tires <NUM> are mounted travels, the pneumatic tires <NUM> each rotate while a bottom portion of the road contact surface <NUM> of the tread portion <NUM> comes into contact with the road surface. When traveling on dry road surfaces, the vehicle on which the pneumatic tires <NUM> are mounted travels by, mainly with friction force between the road contact surface <NUM> and the road surfaces, transmitting driving force and braking force to the road surfaces and generating turning force. Additionally, during traveling on wet road surfaces, water between the road contact surface <NUM> and the road surfaces enters the grooves <NUM> such as the circumferential grooves <NUM> and the lug grooves <NUM> and the sipes <NUM>, and the vehicle travels while the water between the road contact surface <NUM> and the road surfaces is drained through the grooves <NUM> and the sipes <NUM>. As a result, the ground contact surface <NUM> is easily brought into contact with the road surfaces, and the vehicle can travel with friction force between the road contact surface <NUM> and the road surfaces.

When a vehicle travels on snow-covered road surfaces or icy road surfaces, the vehicle travels using the edge effect of the circumferential groove <NUM>, the lug grooves <NUM>, and the sipes <NUM>. In other words, when a vehicle travels on snow-covered road surfaces or icy road surfaces, the vehicle travels using the resistance caused by the edges of the circumferential groove <NUM>, the edges of the lug grooves <NUM>, and the edges of the sipes <NUM> biting the snow or ice surface. Furthermore, in the pneumatic tire <NUM> according to the present embodiment, when the vehicle travels on snow-covered road surfaces or icy road surfaces, stud pins (not illustrated) are inserted into the pin holes <NUM>, and thus the vehicle can travel using the resistance resulting from the stud pins biting the snow or ice surfaces. When the vehicle travels on snow-covered road surfaces or icy road surfaces, the resistance between the snow-covered road surfaces or the icy road surface and the road contact surface <NUM> can be increased due to the edge effects and the resistance resulting from the stud pins biting the snow or ice surfaces, and the running performance of the vehicle having the pneumatic tire <NUM> mounted thereon can be ensured.

Since the edge effect of the sipe <NUM> is also effective in ensuring the running performance during traveling on snow-covered road surfaces and icy road surfaces, it is effective to dispose as many sipes <NUM> as possible in the road contact surface <NUM>. However, when the pin holes <NUM> for stud pins are formed in the road contact surface <NUM>, failures are likely to occur in the sipe blade <NUM> that forms the sipe <NUM> of which the distance to the pin hole <NUM> is small. Thus, it is difficult to dispose the sipe <NUM> at or near the pin hole <NUM>. However, in the present embodiment, the pin hole neighboring sipe <NUM> is more rigid than the normal sipe <NUM>, and failures are less likely to occur in the sipe blade <NUM> that forms the pin hole neighboring sipe <NUM>. As a result, the sipes <NUM> can be disposed at or near the pin holes <NUM>, and more sipes <NUM> can be disposed in the road contact surface <NUM>. Accordingly, the edge components of the sipe <NUM> can be increased to increase the edge effect, and the performance on ice and snow can be ensured. As a result, the durability of the sipe blades <NUM> and the performance on ice and snow can be provided in a compatible manner.

Additionally, the maximum depth H1 of the pin hole neighboring sipe <NUM> is shallower than the maximum depth H2 of the normal sipe <NUM>. And thus, the rigidity of the entire groove formed by the wall surface and the bottom portion that forms the pin hole neighboring sipe <NUM> can be more reliably increased as compared to the rigidity of the entire groove formed by the wall surface or the bottom portion that forms the normal sipe <NUM>. As a result, it is possible to more reliably suppress failures such as bending of the sipe blade <NUM> generated due to the reaction force acting to the sipe blade <NUM> from the rubber member forming the sipe <NUM> when the sipe blade <NUM> that forms the pin hole neighboring sipe <NUM> in which the amount of the rubber member disposed between the pin hole <NUM> and the pin hole neighboring sipe <NUM> is small is pulled out of the pin hole neighboring sipe <NUM>. As a result, the durability of the sipe blades <NUM> and the performance on ice and snow can be provided more reliably in a compatible manner.

In addition, since the ratio of the maximum depth H1 of the pin hole neighboring sipe <NUM> to the maximum depth H2 of the normal sipe <NUM> is within the range of <NUM> ≤ (H1/H2) ≤ <NUM>, it is possible to more reliably provide the durability of the sipe blade <NUM> and the performance on ice and snow. That is, when the ratio of the maximum depth H1 of the pin hole neighboring sipe <NUM> to the maximum depth H2 of the normal sipe <NUM> is (H1/H2) < <NUM>, since the maximum depth H1 of the pin hole neighboring sipe <NUM> is too shallow, the pin hole neighboring sipe <NUM> may wear prematurely. In this case, since the edge components are reduced, the performance on ice and snow may deteriorate prematurely. Additionally, when the maximum depth H1 of the pin hole neighboring sipe <NUM> is too shallow, the pin hole neighboring sipe <NUM> may wear prematurely as compared to other sipes <NUM>, the appearance may degrade. In addition, when the ratio of the maximum depth H1 of the pin hole neighboring sipe <NUM> to the maximum depth H2 of the normal sipe <NUM> is (H1/H2) > <NUM>, since the maximum depth H1 of the pin hole neighboring sipe <NUM> is too deep, it may be difficult to form the pin hole neighboring sipe <NUM> in a shape having higher rigidity than the shape of the normal sipe <NUM>. In this case, since it is difficult to increase the rigidity of the sipe blade <NUM> that forms the pin hole neighboring sipe <NUM>, it may be difficult to suppress failures such as bending of the sipe blade <NUM> by the force acting from the rubber member forming the sipe <NUM> to the sipe blade <NUM> when the sipe blade <NUM> that forms the pin hole neighboring sipe <NUM> in which the amount of the rubber member disposed between the pin hole <NUM> and the sipe blade <NUM> is small is pulled out of the pin hole neighboring sipe <NUM>.

In contrast, when the ratio of the maximum depth H1 of the pin hole neighboring sipe <NUM> to the maximum depth H2 of the normal sipe <NUM> is in the range of <NUM> ≤ (H1/H2) ≤ <NUM>, the depth of the pin hole neighboring sipe <NUM> can be ensured. Thus, the edge effect of the pin hole neighboring sipe <NUM> can be ensured continuously, and degradation of the appearance when the tread portion <NUM> wears can be suppressed. Furthermore, the pin hole neighboring sipe <NUM> can be more reliably formed in a shape that is more rigid than the shape of the normal sipe <NUM>, and the rigidity of the sipe blade <NUM> that forms the pin hole neighboring sipe <NUM> can be more reliably increased. Thus, failures of the sipe blade <NUM> can be more reliably suppressed. As a result, the durability of the sipe blades <NUM> and the performance on ice and snow can be provided more reliably in a compatible manner.

Additionally, in the tire molding mold <NUM> according to the present embodiment, the pin neighboring blade <NUM> in which the distance Dsm from the mold pin <NUM> and the diameter Dpm of the mold pin <NUM> satisfy a relationship of (Dsm/Dpm) ≤ <NUM> is formed in a high rigidity shape having higher rigidity than the normal blade <NUM> of which the distance Dsm from the mold pin <NUM> is the smallest among the sipe blade <NUM> in which the distance Dsm from the mold pin <NUM> and the diameter Dpm of the mold pin <NUM> satisfy a relationship of (Dsm/Dpm) > <NUM>. Thus, during vulcanization molding of the pneumatic tire <NUM>, when the pin neighboring blade <NUM> in which the amount of the rubber member of the tread portion <NUM> disposed between the mold pin <NUM> and the pin neighboring blade <NUM> is small due to the small distance Dsm from the mold pin <NUM> is pulled out of the pin hole neighboring sipe <NUM> formed by the pin neighboring blade <NUM>, even when a large reaction force acts on the pin neighboring blade <NUM> from the rubber member, the occurrence of failures such as bending of the pin neighboring blade <NUM> can be suppressed.

Additionally, since the sipe blades <NUM> are disposed at positions where the distance Dsm from the mold pin <NUM> and the diameter Dpm of the mold pin <NUM> satisfy a relationship of (Dsm/Dpm) ≥ <NUM>, it is possible to suppress the distance Dsm from the mold pin <NUM> of any sipe blade <NUM> from becoming too small. As a result, it is possible to suppress the amount of the rubber member disposed between the sipe blade <NUM> and the mold pin <NUM> from becoming too small during vulcanization molding of the pneumatic tire <NUM>. Moreover, it is possible to suppress the occurrence of failures such as bending in the sipe blade <NUM> due to a reaction force acting from the rubber member forming the sipe <NUM> when the sipe blade <NUM> is pulled out of the sipe <NUM>.

In addition, since the pin neighboring blade <NUM> has higher rigidity than the normal blade <NUM>, failures are less likely to occur. Thus, when the pin neighboring blades <NUM> are disposed at or near the mold pins <NUM>, the sipe blades <NUM> can also be disposed at or near the mold pins <NUM>, and more sipe blades <NUM> can be disposed on the tread molding surface <NUM>. And thus, more sipes <NUM> can be disposed in the road contact surface <NUM> of the pneumatic tire <NUM>. Accordingly, when vulcanization molding of the pneumatic tire <NUM> is performed using the tire molding mold <NUM> according to the present embodiment, the edge components of the sipe <NUM> can be increased, and thus the edge components can be improved. And thus, the performance on ice and snow of the pneumatic tire <NUM> can be ensured. As a result, the durability of the sipe blades <NUM> and the performance on ice and snow can be provided in a compatible manner.

Note that in the embodiment described above, the pin hole neighboring sipe <NUM> of the pneumatic tire <NUM> is formed in a high rigidity shape having higher rigidity than the normal sipe <NUM> by making the maximum depth H1 shallower than the maximum depth H2 of the normal sipe <NUM>. However, the pin hole neighboring sipe <NUM> may have a higher rigidity shape without making the depth shallower than the normal sipe <NUM>. <FIG> is a modified example of the pneumatic tire <NUM> according to the embodiment, and is an explanatory diagram in a case where the width of the sipe <NUM> is different. The pin hole neighboring sipe <NUM> may be formed such that the maximum width W1 of the pin hole neighboring sipe <NUM> is greater than the maximum width W2 of the normal sipe <NUM>, for example, and thus the shape of the pin hole neighboring sipe <NUM> is more rigid than the normal sipe <NUM>. In this case, the ratio of the maximum width W1 of the pin hole neighboring sipe <NUM> to the maximum width W2 of the normal sipe <NUM> is preferably in the range of <NUM> ≤ (W1/W2) ≤ <NUM>.

That is, when the ratio of the maximum width W1 of the pin hole neighboring sipe <NUM> to the maximum width W2 of the normal sipe <NUM> is (W1/W2) < <NUM>, the maximum width W1 of the pin hole neighboring sipe <NUM> is not significantly greater than the maximum width W2 of the normal sipe <NUM>, and thus it may be difficult to form the pin hole neighboring sipe <NUM> in a shape that can effectively improve the rigidity. In this case, during vulcanization molding of the pneumatic tire <NUM>, it may be difficult to effectively suppress the occurrence of failures such as bending in the sipe blade <NUM> that forms the pin hole neighboring sipe <NUM>. In addition, when the ratio of the maximum width W1 of the pin hole neighboring sipe <NUM> to the maximum width W2 of the normal sipe <NUM> is (W1/W2) > <NUM>, the maximum width W2 of the normal sipe <NUM> is too narrow, and thus it may be difficult to exhibit the edge effect of the normal sipe <NUM>.

In contrast, when the ratio of the maximum width W1 of the pin hole neighboring sipe <NUM> to the maximum width W2 of the normal sipe <NUM> is in the range of <NUM> ≤ (W1/W2) ≤ <NUM>, it is possible to form the pin hole neighboring sipe <NUM> in a shape that can more reliably increase the rigidity while ensuring the edge effect of the normal sipe <NUM> and suppress failures of the sipe blade <NUM> that forms the pin hole neighboring sipe <NUM>. As a result, the durability of the sipe blades <NUM> and the performance on ice and snow can be provided more reliably in a compatible manner.

Additionally, the pin hole neighboring sipe <NUM> may be formed oscillating in the width direction in the depth direction, and thus formed in a shape having higher rigidity than the normal sipe <NUM>. That is, the pin hole neighboring sipe <NUM> may be formed as a so-called three-dimensional sipe that oscillates in the width direction of the sipe <NUM> with respect to both the length direction and the depth direction of the sipe <NUM>. When the pin hole neighboring sipe <NUM> is formed as a three-dimensional sipe, the pin hole neighboring sipe <NUM> includes a wall surface having a bent shape with an amplitude in the width direction of the sipe <NUM> in both a cross-sectional view in which the length direction of the sipe is a normal direction and a cross-sectional view in which the depth direction of the sipe <NUM> is a normal direction. When the normal sipe <NUM> is formed as a so-called two-dimensional sipe and the pin hole neighboring sipe <NUM> is formed as a three-dimensional sipe, the pin hole neighboring sipe <NUM> can be more reliably formed in a shape having higher rigidity than the normal sipe <NUM>. As a result, the durability of the sipe blades <NUM> and the performance on ice and snow can be provided more reliably in a compatible manner. In this case, the two-dimensional sipe refers to the sipe <NUM> including a wall surface having a straight shape in any cross-sectional view (cross-sectional views including the width direction and the depth direction of the sipe <NUM>) in which the length direction of the sipe <NUM> is a normal direction.

In the pneumatic tire <NUM> according to the embodiment described above, the pin hole neighboring sipe <NUM> formed in a shape having higher rigidity than the normal sipe <NUM> is not defined in detail. However, the pin hole neighboring sipe <NUM> formed in a shape having higher rigidity than the normal sipe <NUM> may be some of the plurality of pin hole neighboring sipes <NUM>. <FIG> is an explanatory diagram of a modified example of the pneumatic tire <NUM> according to the embodiment, illustrating bending of the pin hole neighboring sipe <NUM>. Only the pin hole neighboring sipes <NUM> in which the number of bend points in the length direction of the pin hole neighboring sipe <NUM> is less than three among the plurality of pin hole neighboring sipes <NUM> may be formed in a high rigidity shape. That is, even when the pin hole neighboring sipes <NUM> are bent or not bent in a plan view, only the pin hole neighboring sipes <NUM> in which there is one bend point <NUM> as illustrated in <FIG> or there are two bend points <NUM> as illustrated in <FIG> may be formed in a high rigidity shape. That is, when the pin hole neighboring sipe <NUM> has three bend points <NUM> as illustrated in <FIG> or has four or more bend points, the pin hole neighboring sipe <NUM> may not be formed in a high rigidity shape. For example, the maximum depth H1 of the pin hole neighboring sipe <NUM> having three or more bend points <NUM> may not be shallower than the maximum depth H2 of the normal sipe <NUM>.

When the pin hole neighboring sipe <NUM> has three or more bend points <NUM>, the sipe blade <NUM> that forms the pin hole neighboring sipe <NUM> also has three or more bend points and thus the rigidity of the sipe blade <NUM> can be ensured. And thus, the occurrence of failures such as bending of the sipe blade <NUM> can be suppressed. In addition, by making the maximum depth H1 of the pin hole neighboring sipe <NUM> having three or more bend points <NUM> approximately equal to, rather than shallower than, the maximum depth H2 of the normal sipe <NUM>, it is possible to suppress the premature wearing of the pin hole neighboring sipe <NUM>. As a result, the edge effect of the pin hole neighboring sipe <NUM> can be ensured for the identical period as the normal sipe <NUM>. As a result, the durability of the sipe blades <NUM> and the performance on ice and snow can be provided more reliably in a compatible manner.

In addition, when some pin hole neighboring sipes <NUM> are formed in a high rigidity shape, the pin hole neighboring sipes <NUM> to be formed in a high rigidity shape may be set in consideration of the division positions 101a between the sectors <NUM> of the tire molding mold <NUM> in the land portion <NUM>. <FIG> is an explanatory diagram of a modified example of a pneumatic tire <NUM> according to the embodiment, illustrating the vicinity of the division position of the sector <NUM>. The tread portion <NUM> of the pneumatic tire <NUM> is formed in a state where a plurality of sectors <NUM> (see <FIG>) of the tire forming mold <NUM> (see <FIG>) are connected in an annular shape in the tire circumferential direction. In this case, the pin hole neighboring sipes <NUM> located at or near the positions corresponding to the division positions 101a (see <FIG>) between the sectors <NUM> of the tire molding mold <NUM> in the land portion <NUM> among the plurality of pin hole neighboring sipes <NUM> disposed in the tread portion <NUM> may be formed in a high rigidity shape. That is, when the positions corresponding to the division positions 101a between the sectors <NUM> of the tire molding mold <NUM> in the landing position <NUM>, that is, the positions facing the division positions 101a, are division corresponding positions <NUM>, only the pin hole neighboring sipes <NUM> located at or near the division corresponding positions <NUM> among the plurality of pin hole neighboring sipes <NUM> may be formed in a shape that has higher rigidity than the normal sipe <NUM>.

Here, at or near the division corresponding position <NUM> refers to a range of <NUM> or less from the division corresponding position <NUM> in the tire circumferential direction. Thus, only the pin hole neighboring sipes <NUM> of which at least a portion is located in the range of <NUM> or less from the division corresponding positions <NUM> among the plurality of pin hole neighboring sipes <NUM> are preferably formed in a high rigidity shape.

In the sipe blade <NUM> disposed at or near the division position 101a of the sector <NUM> among the plurality of sipe blades <NUM> disposed in one sector <NUM>, the difference between the direction of moving the sector <NUM> when the tire molding mold <NUM> is detached after vulcanization molding of the pneumatic tire <NUM> and the direction of the sipe blade <NUM> extending from the tread molding surface <NUM> is larger than the sipe blades <NUM> disposed at a position away from the division position 101a. That is, in the sipe blade <NUM> disposed at or near the division position 101a of the sector <NUM>, an inclination angle of the sipe blade <NUM> with respect to the direction of moving the sector <NUM> is larger than that of the sipe blades <NUM> disposed at a position away from the division position 101a. Thus, the sipe blade <NUM> disposed at or near the division position 101a of the sector <NUM> receives a larger reaction force acting from the sipe <NUM> when the tire molding mold <NUM> is detached from the pneumatic tire <NUM> than the sipe blade <NUM> disposed at a position away from the division position 101a of the sector <NUM>.

Accordingly, when only some pin hole neighboring sipes <NUM> are to be formed in a shape having higher rigidity than the normal sipes <NUM>, by forming only the pin hole neighboring sipes <NUM> located at or near the division corresponding positions <NUM> in a high rigidity shape, it is possible to ensure the rigidity of the sipe blade <NUM> in which the reaction force acting from the sipe <NUM> when the tire molding mold <NUM> is detached from the pneumatic tire <NUM> is particularly large. Accordingly, it is possible to suppress the occurrence of failures such as bending of the sipe blades <NUM>. Additionally, by making the maximum depth H1 of the pin hole neighboring sipe <NUM> located away from the division corresponding position <NUM> approximately equal to, rather than shallower than, the maximum depth H2 of the normal sipe <NUM>, the premature wearing of the pin hole neighboring sipe <NUM> can be suppressed, and the edge effect of the pin hole neighboring sipe <NUM> can be ensured for the identical period as the normal sipe <NUM>. As a result, the durability of the sipe blades <NUM> and the performance on ice and snow can be provided more reliably in a compatible manner.

Additionally, in the tire molding mold <NUM> of the embodiment described above, the plurality of sipe blades <NUM> included in the tire molding mold <NUM> are all made of an identical material, but the material may vary between sipe blades <NUM> as necessary. The pin neighboring blade <NUM> and the normal blade <NUM> may differ from each other in material such that, for example, the relationship between the material strength S1 of the pin neighboring blade <NUM> and the material strength S2 of the normal blade <NUM> is S2 < S1. In this case, the material strength S1 of the pin neighboring blade <NUM> and the material strength S2 of the normal blade <NUM> may be, for example, the tensile strength and hardness of the material forming the pin neighboring blade <NUM> and the normal blade <NUM>. Thus, in a case where, for example, tensile strength is used as the material strength compared between the pin neighboring blade <NUM> and the normal blade <NUM>, the tensile strength of the material forming the pin neighboring blade <NUM> is preferably greater than the tensile strength of the material forming the normal blade <NUM>.

In this way, the relationship between the material strength S1 of the pin neighboring blade <NUM> and the material strength S2 of the normal blade <NUM> is S2 < S1, thus allowing the pin neighboring blade <NUM> to be reliably made more rigid than the normal blade <NUM>. Accordingly, failures in the pin neighboring blade <NUM> such as bending and folding of the pin neighboring blade <NUM> can be reliably suppressed. As a result, the durability of the sipe blades <NUM> can be reliably improved.

Additionally, the pin neighboring blade <NUM> and the normal blade <NUM> preferably have a relationship between the surface roughness R1 of the pin neighboring blade <NUM> and the surface roughness R2 of the normal blade <NUM> being R2 > R1. In this case, as the surface roughness R1 of the pin neighboring blade <NUM> and the surface roughness R2 of the normal blade <NUM>, so-called arithmetic mean roughness Ra is used, for example. Because the surface roughness R1 of the pin neighboring blade <NUM> is smaller than the surface roughness R2 of the normal blade <NUM>, frictional resistance offered in response to pullout of the pin neighboring blade <NUM> from the sipe <NUM> can be made smaller than the frictional resistance offered in response to pullout of the normal blade <NUM> from the sipe <NUM>. Thus, in a case where the sectors <NUM> of the tire molding mold <NUM> are detached from the pneumatic tire <NUM> after vulcanization molding, the pin neighboring blade <NUM> can be easily pulled out from the sipe <NUM>, and even in a case where the reaction force from the rubber member forming the sipe <NUM> acts on the pin neighboring blade <NUM>, failure such as bending and folding of the pin neighboring blade <NUM> can be reliably suppressed. As a result, the durability of the sipe blades <NUM> can be reliably improved.

Additionally, in the pneumatic tire <NUM> according to the embodiment described above, the position of the end portion 21a in the length direction of the pin hole neighboring sipe <NUM> is closest to the pin hole <NUM>, but the position other than the end portion 21a of the pin hole neighboring sipe <NUM> may be disposed closest to the pin hole <NUM>. Additionally, the pneumatic tire <NUM> may include the pin hole <NUM> and the sipe <NUM> disposed in the tread portion <NUM>, and the tread pattern is not limited to that illustrated in the embodiment.

<FIG> is a table showing results of performance evaluation tests of pneumatic tires. Hereinafter, evaluation tests of performance of the pneumatic tire <NUM> described above performed on pneumatic tires of Conventional Examples and the pneumatic tires <NUM> according to the embodiments of the present invention will be described. The performance evaluation tests were conducted for the durability of the tire molding mold when the pneumatic tire was subjected to vulcanization molding, and the performance on ice and snow, which is the running performance on icy and snowy road surfaces.

The performance evaluation tests were conducted on a pneumatic tire having a tire nominal size of <NUM>/55R16 94T, defined by JATMA. The evaluation method for the respective test items is as follows. The durability of the tire molding mold was evaluated as follows. Vulcanization molding of test tires was performed using the tire molding mold. After that, bending of the pin neighboring blade <NUM> which is the sipe blade <NUM> for the pin hole neighboring sipe <NUM> and is the sipe blade <NUM> where bending is likely to occur was examined. The pin neighboring blades <NUM> which were bent by <NUM>° or more were repaired, and the number of repaired pin neighboring blades <NUM> was measured. Furthermore, after vulcanization molding was performed <NUM> times, the total number of the pin neighboring blades <NUM> repaired was calculated, and the reciprocals of the totals calculated were expressed as index values with the Conventional Example being assigned the value of <NUM>. Larger values indicate a smaller number of the pin neighboring blades <NUM> repaired and superior mold durability.

Additionally, the performance on ice and snow was evaluated as follows. The test tires mounted on the rim wheels were mounted on a test vehicle, and the braking distances from starting braking at a speed of <NUM>/h to reading <NUM>/h were measured on a test course of icy road surfaces. The reciprocals of the measured braking distances were expressed as index values with Conventional Example being assigned the value of <NUM> Larger index values indicate shorter braking distance on icy road surfaces and superior braking performance on icy road surfaces. Note that, about performance on ice and snow, when the index value is <NUM> or more, a decrease in braking performance on icy road surfaces is suppressed as compared with Conventional Example.

The performance evaluation test was carried out on <NUM> types of pneumatic tires, or in other words, the pneumatic tires of Conventional Example which was an example of a conventional pneumatic tire, and Examples <NUM> to <NUM>, which were the pneumatic tires <NUM> according to the present invention. Among these tires, in Conventional Example, the pin hole neighboring sipe <NUM> is not formed in a high rigidity shape having higher rigidity than the normal sipe <NUM>, and the pin hole neighboring sipe <NUM> and the normal sipe <NUM> have the identical reference depth and width.

In contrast, in Examples <NUM> to <NUM>, which are examples of the pneumatic tire <NUM> according to the present invention, all pin hole neighboring sipes <NUM> are formed in a high rigidity shape having higher rigidity than the normal sipes <NUM>. Furthermore, in the pneumatic tires <NUM> according to Examples <NUM> to <NUM>, the ratios (H1/H2) of the maximum depth H1 of the pin hole neighboring sipe <NUM> to the maximum depth H2 of the normal sipe <NUM>, the ratios (W1/W2) of the maximum width W1 of the pin hole neighboring sipe <NUM> to the maximum width W2 of the normal sipe <NUM>, the shapes of the pin hole neighboring sipes <NUM>, whether only the pin hole neighboring sipe <NUM> in which the number of bend points <NUM> is less than three will be formed in a high rigidity shape, and whether only the pin hole neighboring sipe <NUM> located at or near the division corresponding position <NUM> will be formed in a high rigidity shape are respectively different.

Claim 1:
A pneumatic tire comprising:
a plurality of sipes disposed in a land portion formed in a tread portion; and
a plurality of pin holes for stud pins disposed in the land portion,
the sipes being disposed at positions where a distance Ds from the pin hole and a diameter Dp of the pin hole satisfy a relationship of (Ds/Dp) ≥ <NUM>,
the sipe, among the plurality of sipes, in which the distance Ds from the pin hole and the diameter Dp of the pin hole satisfy a relationship of (Ds/Dp) ≤ <NUM>, being defined as a pin hole neighboring sipe, characterised by
the sipe of which the distance Ds from the pin hole is the smallest, among the sipes in which the distance Ds from the pin hole and the diameter Dp of the pin hole satisfy a relationship of (Ds/Dp) > <NUM>, being defined as a normal sipe, and the pin hole neighboring sipe being formed in a high rigidity shape having higher rigidity than the normal sipe.