JP2019206316A - tire - Google Patents

Abstract

To provide a tire capable of suppressing vulcanization molding failure of a projection part arranged on a major groove.SOLUTION: In a tire, a major groove extending in a tire circumferential is provided on a tread part 2. The major groove 3 has a pair of groove walls 3a and a groove bottom part 3b. On the groove bottom part 3b, at least one projection part 10 projecting to a tire radial direction is formed. The projection part 10 includes a pair of side faces 11 separated from the pair of groove walls 3a so as to be faced to the pair of groove walls 3a. A small projection part 15 extending in the tire radial direction is provided on at least either of the pair of side faces 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tire, and more particularly to a tire in which a raised portion for preventing stone biting is provided at the bottom of a main groove.

  Various tires in which a main groove extending in the tire circumferential direction is arranged in the tread portion have been proposed. In general, the main groove has a relatively large groove width in order to obtain high drainage. On the other hand, the main groove is liable to have a stone bite in which foreign matter such as pebbles on the road surface enters during traveling. The stone that has entered the main groove may cause damage to the groove wall and the bottom of the main groove. Conventionally, in order to suppress biting of stone, a tire has been proposed in which a raised portion in which a groove bottom portion is raised is arranged in a main groove. As related technology, there is Patent Document 1 below.

JP 2000-185525 A

  A mold for vulcanizing the tread portion of the tire includes a rib for forming a main groove and a recess for forming the raised portion in which a part of the rib is recessed. At the time of manufacturing the tire, the raised portion is vulcanized and molded by allowing a part of the tread rubber of the raw tire to enter the recess. At this time, air remained in the concave portion, and in particular, there was a tendency that a molding defect such as a bear (dent due to residual air) occurred in the raised portion. In particular, in recent years, in order to increase the stone biting suppression effect, it has been required to increase the height of the raised portion, and there has been a tendency that the above-described molding defects are likely to occur.

  The present invention has been devised in view of the actual situation as described above, and has as its main object to provide a tire capable of suppressing a vulcanization molding failure of a raised portion arranged in a main groove.

  The present invention is a tire in which a main groove extending in a tire circumferential direction is provided in a tread portion, and the main groove includes a pair of groove walls and a groove bottom portion, and the groove bottom portion includes a tire radial direction. At least one raised portion that protrudes from the pair of side walls separated from the pair of groove walls so as to face the pair of groove walls, and at least one of the pair of side surfaces. Are provided with small protrusions extending in the tire radial direction.

  In the tire according to the aspect of the invention, it is preferable that the small protrusion portion continuously extends to at least one of the pair of groove walls through the groove bottom portion.

  In the tire according to the aspect of the invention, it is preferable that the small protruding portion extends to a groove edge of the main groove, and the width of the small protruding portion is gradually reduced toward the inner side in the tire radial direction on the groove wall.

  In the tire according to the aspect of the invention, the raised portion includes a top surface that connects the pair of side surfaces on the outer side in the tire radial direction, and the small protrusion portion continuously extends from the at least one side surface to the top surface. It is desirable.

  In the tire according to the aspect of the invention, it is preferable that the width of the small protrusion portion is gradually reduced toward the inner side in the tire radial direction on the side surface.

  In the tire according to the present invention, the small protrusion portion includes a first small protrusion portion disposed on one side in the tire circumferential direction with respect to the center position in the tire circumferential direction of the raised portion, and a tire circumferential direction relative to the center position. It is desirable to include the 2nd small protrusion part distribute | arranged to the other side.

  In the tire according to the present invention, it is preferable that each of the first small protrusion and the second small protrusion is disposed at an end of the raised portion in the tire circumferential direction.

  In the tire of the present invention, the raised portion includes a top surface that connects the pair of side surfaces on the outer side in the tire radial direction, and the first small protrusion portion continuously extends from one of the side surfaces to the top surface. And it is desirable not to be provided on the other side surface.

  In the tire according to the aspect of the invention, it is preferable that the second small protrusion portion continuously extends from the other side surface to the top surface and is not provided on the one side surface.

  In the tire according to the present invention, a length of the protruding portion in the tire circumferential direction is 15 mm or more, and the small protrusion is a first protrusion disposed between the first small protrusion and the second small protrusion. It is desirable to include three small protrusions.

  In the tire of the present invention, it is preferable that the width of the raised portion is 0.20 to 0.40 times the maximum groove width of the main groove.

  In the tire of the present invention, it is desirable that the height of the raised portion is 0.15 to 0.60 times the maximum depth of the main groove.

  In the tire of the present invention, it is desirable that the width of the small protrusion is 0.2 to 0.8 mm.

  In the tire of the present invention, it is desirable that the small protrusions have a height of 0.1 to 0.4 mm.

  At least one raised portion protruding in the tire radial direction is formed at the groove bottom portion of the main groove of the tire of the present invention. The raised portion includes a pair of side surfaces separated from the pair of groove walls so as to face the pair of groove walls of the main groove. At least one of the pair of side surfaces is provided with a small protrusion extending in the tire radial direction.

  In general, the raised portion is vulcanized and molded by a part of a tread rubber of a raw tire entering a recess provided in a rib for forming a main groove of a vulcanization mold. At the time of vulcanization molding of the tire of the present invention, when the rubber enters the recess of the vulcanization mold, the air in the recess is quickly exhausted through the small groove for molding the small protrusion. Therefore, the vulcanization molding defect of the raised portion is effectively suppressed.

It is a cross-sectional view of the tread part of the tire of one embodiment of the present invention. It is an expanded sectional view of the main groove of FIG. It is an expansion perspective view of a main groove and a protruding part. FIG. 4 is an enlarged perspective view of a vulcanization mold used for vulcanization molding of a main groove and a raised portion in FIG. 3.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a cross-sectional view of the tread portion 2 of the tire 1 of the present embodiment. FIG. 1 is a meridian cross-sectional view including the tire rotation axis in a normal state of the tire 1. The tire 1 of the present embodiment is suitably used as a heavy load pneumatic tire, for example. However, the tire 1 of the present invention is not limited to such an embodiment, and may be used as a tire for a passenger car, for example.

  The “normal state” is a no-load state in which the tire is assembled on the normal rim and filled with the normal internal pressure. Hereinafter, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in this normal state.

  The “regular rim” is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA, For ETRTO, "Measuring Rim".

  “Regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. “JAMATA” is “maximum air pressure”, TRA is “TIRE LOAD LIMITS AT” The maximum value described in “VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” in the case of ETRTO.

  As shown in FIG. 1, the tread portion 2 of the tire 1 is provided with a plurality of main grooves 3 extending in the tire circumferential direction. The main groove 3 includes a shoulder main groove 4 arranged closest to the tread end Te side and a crown main groove 5 arranged closer to the tire equator C side than the shoulder main groove 4. However, the arrangement of the main grooves 3 is not limited to such an aspect.

  The tread end Te is a contact position on the outermost side in the tire axial direction when a normal load is applied to the tire 1 in the normal state and contacted to a plane with a camber angle of 0 °.

  “Regular load” is the load determined by each standard for each tire in the standard system including the standard on which the tire is based. “JATMA” is “Maximum load capacity”, TRA is “TIRE LOAD LIMITS” The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO.

  The main groove 3 has a pair of groove walls 3a and a groove bottom 3b. At least one raised portion 10 protruding in the tire radial direction is formed on the groove bottom portion 3b of the main groove 3.

  FIG. 2 shows an enlarged cross-sectional view of the main groove 3. The main groove 3 shown in FIG. 2 is a shoulder main groove 4. However, the configuration of the main groove 3 described below may be applied to the crown main groove 5. As shown in FIG. 2, the raised portion 10 includes a pair of side surfaces 11 and a top surface 12 that joins the side surfaces 11 on the outer side in the tire radial direction. Each side surface 11 of the raised portion 10 is separated from the groove wall 3 a so as to face the groove wall of the main groove 3.

  The width W2 of the raised portion 10 is preferably 0.20 to 0.40 times the maximum groove width W1 of the main groove 3, for example. The height h1 of the raised portion 10 is preferably 0.15 to 0.60 times the maximum depth d1 of the main groove 3, for example. Such a raised portion 10 can exhibit an excellent stone biting suppression effect while maintaining the drainability of the main groove 3.

  FIG. 3 shows a perspective view of the main groove 3 and the raised portion 10. As shown in FIG. 3, at least one of the side surfaces of the raised portion 10 is provided with a small protrusion portion 15 extending in the tire radial direction. In FIG. 1, the small protrusion 15 is omitted.

  In general, the raised portion 10 provided in the main groove 3 is vulcanized and molded by a part of the tread rubber of the raw tire entering a recess provided in the rib for forming the main groove of the vulcanization mold. . At the time of vulcanization molding of the tire 1 of the present invention, when the rubber enters the recess of the vulcanization mold, the air in the recess is quickly discharged through the small groove for forming the small protrusion 15. Therefore, the vulcanization molding defect of the raised portion is effectively suppressed.

  In addition, since the spew (small projections resulting from the vent hole of the vulcanization mold) is not formed on the top surface 12 and the side surface 11 of the raised portion 10 of the present invention, the appearance of the tire is not deteriorated. Further, when the tire of the present invention is manufactured, it is not necessary to remove spew or to clean the vent hole, and the productivity of the tire can be increased.

  In order to reliably discharge the air in the mold during vulcanization molding, it is desirable that the width of the small protrusion 15 is 0.2 to 0.8 mm, for example. Moreover, it is desirable that the height of the small protrusion 15 is 0.1 to 0.4 mm, for example.

  For example, the small protrusion 15 preferably extends from at least the edge of the side surface 11 and the top surface 12 to the inner side in the tire radial direction than the depth of 50% of the main groove 3. For example, the small protrusion 15 of the present embodiment extends in the tire radial direction over the entire side surface 11 of the raised portion 10. In other words, the small protrusion 15 extends in the tire radial direction from at least the edge of the side surface 11 and the top surface 12 to the groove bottom 3b.

  It is desirable that the small protrusion 15 extends continuously to at least one of the pair of groove walls 3a through the groove bottom 3b. For example, in the groove wall 3a of the main groove 3, the small protrusion 15 preferably extends from the groove bottom 3b to the outer side in the tire radial direction than the depth of 50% of the main groove 3. The small protrusion 15 of the present embodiment extends from the groove bottom 3b to the groove edge 3e of the main groove 3. Such small protrusions 15 can effectively suppress the occurrence of bears in the raised portions.

  The small protrusions 15 preferably extend along the tire radial direction without being inclined in the tire circumferential direction on each of the side surface 11 of the raised portion 10 and the groove wall 3a of the main groove 3. Specifically, when the side surface 11 or the groove wall 3a is viewed from the front, the small protrusions 15 are desirably arranged at an angle of ± 5 ° with respect to the tire radial direction, for example. The protrusion 15 has an angle of 0 ° with respect to the tire radial direction when the side surface 11 or the groove wall 3a is viewed from the front.

  The width of the small protrusion 15 is preferably gradually reduced toward the inside in the tire radial direction on each of the side surface 11 of the raised portion 10 and the groove wall 3a of the main groove 3. Thereby, the small protrusion part 15 is formed in the minimum width in the groove bottom part 3b. The minimum width of the small protrusion 15 is preferably 0.25 to 0.50 times the maximum width of the small protrusion 15. As a result, the small grooves of the vulcanization mold forming the small protrusions 15 are less likely to be clogged, and the bear is reliably prevented.

  It is desirable that the small protrusion 15 extends continuously from the side surface 11 to the top surface 12 of the raised portion 10. Further, it is desirable that the small protrusion 15 extends on the top surface 12 along the tire axial direction. The small protrusion 15 has a length on the top surface 12 of preferably 50% or more, more preferably 80% or more of the width of the top surface 12. The small protrusion portion 15 of the present embodiment extends from one end of the top surface 12 to the other end on the top surface 12. Such a small protrusion 15 can effectively suppress the bear on the top surface 12.

  For example, the small protrusion 15 has a certain width on the top surface 12. Further, the width of the small protrusion 15 on the top surface 12 corresponds to the maximum width of the entire small protrusion 15. Thereby, since rubber enters the small groove of the vulcanization mold forming the small protrusion 15 from the top surface 12 side, the air in the concave portion of the vulcanization mold is more easily discharged.

  For example, a plurality of small protrusions 15 are preferably provided on the raised portion 10. The small protrusion 15 of the present embodiment includes a first small protrusion 16 disposed on one side in the tire circumferential direction from the center position in the tire circumferential direction of the raised portion 10 and the other in the tire circumferential direction from the center position. 2nd small protrusion part 17 distribute | arranged to the side. In a more desirable mode, each of the first small protrusion 16 and the second small protrusion 17 is disposed at the end of the raised portion 10 in the tire circumferential direction. The 1st small protrusion part 16 and the 2nd small protrusion part 17 are useful for suppressing the bear of the edge part of the tire circumferential direction of the protruding part 10. FIG.

  The first small protrusion 16 extends continuously from one side surface 11 to the top surface 12. Further, the first small protrusion 16 extends continuously to the groove wall 3 a of the main groove 3 facing the one side surface 11 and extends to the groove edge 3 e of the main groove 3. On the other hand, the first small protrusion 16 is not provided on the other side surface 11.

  Similarly, the second small protrusion portion 17 continuously extends from the other side surface 11 (the side surface on which the first small protrusion portion 16 is not provided) to the top surface 12. Further, the second small protrusion portion 17 continues to the groove wall 3 a of the main groove 3 facing the other side surface 11 and extends to the groove edge 3 e of the main groove 3. On the other hand, the second small protrusion portion 17 is not provided on one side surface 11 (the side surface on which the first small protrusion portion 16 is provided).

  Such first small protrusions 16 and second small protrusions 17 prevent the appearance of the raised portion 10 from deteriorating. Further, the first small protrusion 16 and the second small protrusion 17 cause an irregular air flow in the main groove 3 when traveling on a dry road surface, and thus air column resonance sound of the main groove 3. Can be reduced. However, it is not limited to such a mode, and the first small protrusion 16 and the second small protrusion 17 are, for example, continuously from one groove edge 3e of the main groove 3 to the other groove edge 3e. It may be extended.

  When the length of the protruding portion 10 in the tire circumferential direction is large, there is a tendency that bears are likely to occur. For this reason, for example, when the maximum length of the protruding portion 10 in the tire circumferential direction is 15 mm or more, the small protrusion 15 is disposed between the first small protrusion 16 and the second small protrusion 17. A third small protrusion (not shown) may be included.

  In this case, for example, it is desirable that the third small protrusion portion continuously extends from one groove edge 3e of the main groove 3 to the other groove edge 3e. Such a 3rd small protrusion part can further accelerate | stimulate discharge | emission of the air in the recessed part of a vulcanization metal mold | die.

  As for each bulging part 10, it is desirable for the length of the tire circumferential direction to increase gradually toward the inner side of a tire radial direction, for example. Each such raised portion 10 has high root rigidity and can exhibit an excellent stone biting suppression effect.

  FIG. 4 shows an enlarged perspective view of a vulcanization mold 20 for vulcanizing the main groove 3 and the raised portion 10 shown in FIG. As shown in FIG. 4, the vulcanization mold 20 used at the time of manufacturing the tire 1 of the present embodiment includes, for example, a rib 21 for forming the main groove 3 and a raised portion 10 in which a part of the rib 21 is recessed ( 3, and the same applies hereinafter.) A recess 22 for formation is provided. The bottom surface 22 a of the concave portion 22 forms the top surface 12 of the raised portion 10, and the inner side surface 22 b of the concave portion 22 forms the side surface 11 of the raised portion 10.

  The vulcanizing mold 20 includes, for example, a small groove 23 for forming the small protrusion 15 described above. The small groove 23 extends to the root of the rib 21 through the bottom surface and the inner side surface of the recess 22 and the outer surface of the rib 21. The vulcanization mold 20 having the small groove 23 can effectively suppress the molding failure of the raised portion 10 due to the above-described action. The small groove 23 of the vulcanizing mold 20 has a shape corresponding to the small protrusion 15 described above.

  As mentioned above, although the tire of one embodiment of the present invention was explained in detail, the present invention is not limited to the above-mentioned specific embodiment, and can be carried out by changing to various modes.

  A heavy-duty pneumatic tire of size 315 / 80R22.5 in which a raised portion including at least one of the small protrusions described above was formed was prototyped based on the specifications in Table 1. As a comparative example, a tire in which a raised portion not including a small protrusion was formed was manufactured as a prototype. The tire of the comparative example is substantially the same as the tire of the example except for the presence or absence of small protrusions. The bear incidence of each test tire was tested. The test method is as follows.

<Bear incidence>
1000 test tires were manufactured, and the occurrence rate of bears generated in the raised portions was measured. A result is an index which makes the bear incidence rate of a comparative example 100, and shows that a bear incidence rate is small and good, so that a numerical value is small.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the tires of the examples suppressed vulcanization molding defects at the raised portions.

2 tread portion 3 main groove 3a groove wall 3b groove bottom portion 10 raised portion 11 side surface 15 small protrusion portion

Claims (14)

A tire provided with a main groove extending in the tire circumferential direction in the tread portion,
The main groove has a pair of groove walls and a groove bottom,
The groove bottom is formed with at least one raised portion protruding in the tire radial direction,
The raised portion includes a pair of side surfaces separated from the pair of groove walls so as to face the pair of groove walls,
At least one of the pair of side surfaces is provided with a small protrusion extending in the tire radial direction,
tire.   2. The tire according to claim 1, wherein the small protrusion extends continuously to at least one of the pair of groove walls through the groove bottom. The small protrusion extends to a groove edge of the main groove,
The tire according to claim 2, wherein the width of the small protrusion portion gradually decreases toward the inner side in the tire radial direction at the groove wall. The raised portion includes a top surface that joins the pair of side surfaces on the outer side in the tire radial direction,
The tire according to any one of claims 1 to 3, wherein the small protrusion portion extends continuously from the at least one side surface to the top surface.   The tire according to claim 4, wherein the width of the small protrusion portion gradually decreases toward the inner side in the tire radial direction on the side surface.   The small protrusions are disposed on the other side in the tire circumferential direction than the center position, and the first small protrusions disposed on the one side in the tire circumferential direction from the center position in the tire circumferential direction of the raised portion. The tire according to any one of claims 1 to 5, comprising a second small protrusion.   The tire according to claim 6, wherein each of the first small protrusion and the second small protrusion is arranged at an end portion of the protruding portion in the tire circumferential direction. The raised portion includes a top surface that joins the pair of side surfaces on the outer side in the tire radial direction,
The tire according to claim 6 or 7, wherein the first small protrusion portion extends continuously from one side surface to the top surface and is not provided on the other side surface.   The tire according to claim 8, wherein the second small protrusion extends continuously from the other side surface to the top surface and is not provided on the one side surface. The length of the protruding portion in the tire circumferential direction is 15 mm or more,
The tire according to any one of claims 6 to 9, wherein the small protrusion includes a third small protrusion disposed between the first small protrusion and the second small protrusion.   The tire according to any one of claims 1 to 10, wherein a width of the raised portion is 0.20 to 0.40 times a maximum groove width of the main groove.   The tire according to any one of claims 1 to 11, wherein a height of the raised portion is 0.15 to 0.60 times a maximum depth of the main groove.   The tire according to any one of claims 1 to 12, wherein the small protrusion has a width of 0.2 to 0.8 mm.   The tire according to any one of claims 1 to 13, wherein a height of the small protrusion is 0.1 to 0.4 mm.

Images