JP2009286204A - Pneumatic tire, sipe formation blade, and manufacturing method for pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of ensuring water discharge performance and enhancing the traveling stability performance of a vehicle on a road surface of a low μ road by effectively suppressing the falling deformation of a block even if an input front/rear force is small. <P>SOLUTION: By installing a blade extending in a thickness direction of a metal thin plate having a cut-in part cut so as to be inclined relative to a thickness direction in a groove of a vulcanization metal die and vulcanizing/treating the tire, the pneumatic tire provided with the block 20 having a sipe 21 having a projection 21p contacting with a wall surface 21n is manufactured in a state that one end 21u is integrated with a wall surface 21m of the sipe 21 (21a, 21b) and the other end 21v is compressed in a tire circumferential direction by the wall surface 21n opposed to the wall surface 21m of the sipe 21. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to improvement of wet performance and braking performance of a pneumatic tire having a block pattern.

Conventionally, in a pneumatic tire having a block pattern, in order to improve the grip performance of the tire when traveling on a low μ road such as an icy road, there is a method of forming a widthwise sipe extending along the tire width direction on the block. Proposed.
As a typical pattern of the width direction sipe, as shown in FIG. 10A, a width that extends in a direction parallel to the tire width direction of the block 51 and opens at both ends in the width direction end of the block 51. A plurality of directional sipes 52 formed in the circumferential direction of the tread block 51 are known. The width-direction sipe 52 has a straight shape in the depth direction and is generally called a two-dimensional sipe. As such a two-dimensional sipe, a straight sipe such as the width-direction sipe 52 as viewed from the tire tread side is a straight sipe. FIG. 10B is a view of the state of the block 51 when the tire 50 including the block 51 formed with the width-direction sipe 52 is sliding on the ice surface S as seen from the tire width direction. The sipe 52 sucks and removes the water film generated on the ice surface S to expose the ice surface S, and the edge effect that the edge 52k of the widthwise sipe 52 scratches the ice surface S. Have a job. However, on the other hand, since the sipe 52 in the width direction is inserted, the collapse of the block 51 occurs and the contact area is reduced. As a result, the contact effect is reduced and tire slip increases. is there.

On the other hand, a method for forming a so-called three-dimensional sipe 62 whose shape also changes in the depth direction is proposed in the block 61, as shown in FIG. ing. FIG. 11B is a view showing a state of the block 61 when the tire 60 including the block 61 in which the three-dimensional sipe 62 is formed is sliding on the ice surface S. As shown in FIG. In the tire 60, since the wall rigidity 62a and 62b of the three-dimensional sipe 62 is brought into contact with each other, the block rigidity is improved, so that the above-mentioned collapse deformation can be suppressed and the ground contact area can be increased. However, since the wall surfaces 62a and 62b are in contact with each other, there is a problem that drainage performance is deteriorated in a low μ road, particularly in a thick water film condition.
Therefore, as shown in FIGS. 12A and 12B, a two-dimensional sipe is adopted as the form of the sipe, and a plurality of protrusions that contact one wall surface 72a of the sipe 72 and the other wall surface 72b at the time of contact. A pneumatic tire 70 including a block 71 provided with 73 is proposed. Even if the sipe 72 is a two-dimensional sipe like the tire 70, by providing the protrusion 73 on the wall surface 72a of the sipe 72, the protrusion 73 provided on one wall surface 72a contacts the other wall surface 72b at the time of contact. Thus, the block rigidity can be increased, so that the collapse of the block 71 can be suppressed and the ground contact area can be increased. Moreover, since the said wall surface 72a, 72b can be prevented from contacting directly by the said protrusion 73, drainage performance can be ensured (for example, refer patent document 1).
JP 2006-168501 A

  However, the protrusion 73 is merely in contact with the wall surface 72b even when the tip is separated from the other wall surface 72b or has a maximum height. The effect of providing 73 was small, and the effect of suppressing the collapse deformation of the block 71 was not sufficient.

  The present invention has been made in view of the conventional problems, and while ensuring drainage performance, even when the input front-rear force is small, it effectively suppresses the collapse of the block and can be used on a low μ road surface. An object of the present invention is to provide a pneumatic tire capable of improving the running stability performance of a vehicle and a method for manufacturing the same.

The invention according to claim 1 of the present application includes a plurality of main grooves (circumferential grooves) provided on the tire tread surface so as to extend along the tire circumferential direction, and a tire width direction on the tire tread surface. A pneumatic tire comprising a plurality of sub-grooves (lateral grooves) provided so as to extend along a plurality of blocks partitioned by the main grooves and the sub-grooves, A sipe extending in the tire width direction is formed, and one wall surface of the sipe protrudes toward the other wall surface facing the one wall surface, and is compressed in the tire circumferential direction by the other wall surface. It is characterized by comprising a compression protrusion that is in contact with the other wall surface and whose free length is longer than the width of the sipe. Here, the “wall surface of the sipe” is, as shown in FIG. 2, when the block 20 is divided into a plurality of small blocks 22 (22 a to 22 c) arranged in the tire circumferential direction by the sipe 21 (21 a, 21 b). , Refers to the side faces of the small blocks 22 adjacent to each other facing the sipe 21. For example, the side surface 21m of the sipe 21a is the side surface of the small block 22a on the sipe 21a side, and the side surface 21n is the side surface of the small block 22b on the sipe 21a side. In the figure, reference numeral 21t denotes the bottom surface of the sipe 21. Further, as shown in FIG. 3, the “free length” is obtained by pressing the compression protrusion 21p protruding from the wall surface 21m of the sipe 21a toward the bottom 21t of the sipe 21a, and the other side of the sipe 21a that has been in contact so far. This is the length L0 of the compression protrusion 21p in a state separated from the wall surface 21n, that is, in a state where the compression force acting on the compression protrusion 21p is released.
Thereby, when the tire slides on a low μ road surface, the compression protrusion becomes a “stick rod”, so that the block rigidity can be improved and the collapse of the block can be effectively suppressed. Moreover, since the small blocks do not contact each other when the compression protrusion is present, the function of the sipe drainage channel can be ensured. In other words, it is possible to suppress the reduction of the ground contact area during braking / driving (input in the front-rear direction) while ensuring the drainage performance, so the frictional force on the low μ road surface of the tire is increased to improve the running stability performance of the vehicle. Can be improved. Further, the compression projection is in contact with the other wall surface in a state where the compression force is received by the other wall surface even when no longitudinal force is input, so that the block rigidity when the longitudinal force is input is ensured. While being able to increase, even if the input front-rear force is small, the block collapse deformation can be effectively suppressed.
Invention of Claim 2 is a pneumatic tire of Claim 1, Comprising: The said sipe protrudes toward the said one wall surface from the said other wall surface, The bottom part side of the said sipe of the said compression protrusion is An auxiliary protrusion that abuts on the surface is further provided. In this way, in addition to the compression protrusion, if the auxiliary protrusion that abuts against the surface of the compression protrusion on the block surface side is provided, the auxiliary protrusion functions as a stopper, so that the compression protrusion is on the bottom side of the sipe. Therefore, not only can the position of contact of the compression projection with the other wall surface be stabilized, but also the compression force in the tire circumferential direction can be stably and reliably applied to the compression projection. Moreover, since the deformation | transformation of the said compression protrusion can be suppressed by this, the collapse collapse deformation | transformation of a block can further be suppressed.

According to a third aspect of the present invention, there is provided a sipe for forming a width direction sipe extending in a tire width direction on a tread surface of the block, which is installed in a groove for forming a block provided in a vulcanization mold. The blade is formed with an incision extending in the tire width direction in the thickness direction of the plate surface, and the incision is inclined toward the bottom of the groove when the blade is installed in the groove. It extends in the direction, and its length is longer than the width of the sipe. When a blade with such a cut (hereinafter referred to as a diagonal cut) is used as a sipe forming blade, after the tire is vulcanized, the blade is pulled out from the vulcanized tire. A rubber member housed in the oblique notch and having one end integrated with one wall surface of the sipe is deformed, and the other member facing the one wall surface, such as the compression protrusion according to claim 1, is deformed. It is possible to easily form a sipe having a protrusion that protrudes toward the wall surface and that comes into contact with the other wall surface in a state in which the compression force is received by the other wall surface.
According to a fourth aspect of the present invention, in the sipe forming blade according to the third aspect, an angle α1 formed by a surface of the blade where the oblique cut is provided and an extension direction of the oblique cut is 45 ° ≦ α1 <. When the thickness of the blade is W and the component in the thickness direction of the blade in the thickness direction of the blade is L1, the L1 is L1 <W <L1 / sinα. By making it in the range satisfying the relationship, a projection such as the compression projection according to claim 1 can be reliably formed on the tire block. When the cross-sectional shape is a polygonal line like the blades 30A and 30B as shown in FIG. 8A or FIG. 9A, the direction perpendicular to the plate surface 30s of the blades 30A and 30B is shown. The thickness D is the thickness of the blades 30A and 30B. Also, the thickness direction is set to a direction perpendicular to the plate surface 30s shown by the arrows in FIGS. 8 (a) and 9 (a).

A fifth aspect of the invention is the sipe forming blade according to the fourth aspect of the invention, wherein a second notch perpendicular to the plate surface of the blade is formed on the opposite side of the blade from the oblique notch. It is characterized by being. Thereby, protrusions such as the auxiliary protrusions according to claim 2 can be reliably formed on the tire block.
The invention according to claim 6 is the sipe forming blade according to claim 5, wherein when the length of the second notch is L2, the L2 is a range satisfying the relationship of L1 + L2 ≦ W. Then, the compression protrusion and the auxiliary protrusion can be reliably formed on the tire block.

  The invention according to claim 7 is a method of manufacturing a pneumatic tire having a block pattern, wherein the sipe forming blade according to any one of claims 3 to 6 is provided with a block on a tread surface. After the tire is vulcanized by placing it at the bottom of the groove of a vulcanization mold provided with a groove for forming, the blade is pulled out from the vulcanized tire and placed on the tread surface of the tire. A plurality of blocks each having a widthwise sipe are formed, and the compression protrusion or the compression protrusion and the auxiliary protrusion are formed on one wall surface of the sipe. Thereby, while ensuring drainage performance, the pneumatic tire which can improve the driving | running | working stability performance of the vehicle on a low micro road surface can be manufactured easily.

Hereinafter, the best mode of the present invention will be described with reference to the drawings.
FIG. 1 is a development view of a tread pattern of a pneumatic tire 10 according to the best mode of the present invention, and FIG. 2 is a partial sectional perspective view of a block 20 in which a sipe according to the present invention is formed. In each figure, 11 is a tread, 12 is a circumferential groove (main groove) provided on the tread surface side of the tread 11 so as to extend along the tire circumferential direction, and 13 is a lateral groove (sub-groove) extending along the tire width direction. , 20 is a rectangular block defined by the circumferential groove 12 and the lateral groove 13. In addition, CL shown with the dashed-dotted line of the figure is a wheel centerline.
Two sipes 21 (21a, 21b) extending in a direction parallel to the tire width direction are formed on the surface of the block 20, and the tire tread surface side of the block 20 is arranged in the tire circumferential direction by the sipes 21. It is divided into three small blocks 22 (22a to 22c) arranged side by side.
The sipe 21 is a two-dimensional sipe having a straight shape in the depth direction, and one wall surface 21m of the sipe 21 is provided with a compression protrusion 21p protruding toward the wall surface 21n facing the wall surface 21m. .

Specifically, as shown in FIG. 3A, the protrusion 21p is a protrusion having a cantilever structure in which one end 21u is integrated with the wall surface 21m and extends in the tire width direction. The other end 21v is restrained by the wall surface 21n. That is, the protrusion 21p is in contact with the wall surface 21n while being compressed in the tire circumferential direction by the wall surface 21n even when no longitudinal force is input to the block 20. Hereinafter, the protrusion 21p is referred to as a compression protrusion.
FIG. 4 is a view of a state of the block 20 as viewed from the tire width direction when a tire including the block 20 having the sipes 21a and 21b having the compression protrusions 21p is sliding on a low μ road surface. . The compression projection 21p is compressed in the tire circumferential direction even when no longitudinal force is input to the block 20. However, when the longitudinal force is input to the block 20, the compression protrusion 21p is a small portion separated by the sipes 21a and 21b. The blocks 22a to 22c further apply a compressive force to the compression protrusion 21p. Accordingly, the reaction force (elastic repulsive force) exerted on the small blocks 22a to 22c by the compression projection 21p when the longitudinal force is input is not input by the longitudinal force as in the conventional projection 73 shown in FIG. The reaction force is larger than the reaction force exerted on the wall surface 72b by the protrusion that is separated from the wall surface 72b in the state or is simply in contact with the wall surface 72b. That is, the block rigidity when the longitudinal force is input can be further increased. Therefore, since the collapse deformation of the block 20 can be effectively suppressed and the reduction of the contact area can be reduced, the frictional force on the low μ road surface can be improved. Further, the wall surface 21m and the wall surface 21n facing each other of the sipe 21 are not brought into contact with each other by the compression protrusion 21p, so that a sufficient drainage channel can be secured.

Here, consider the case where the compression protrusion 21p is released from the restraint by the wall surface 21n. For example, as shown in FIG. 3B, if the compression protrusion 21p is moved away from the wall surface 21n by applying a force in the direction of the bottom 21t of the sipe 21, the compression force acting on the compression protrusion 21p is reduced. Disappear. At this time, the other end 21v of the compression protrusion 21p moves away from the wall surface 21n in the direction of the bottom 21t of the sipe 21 and stops. In this state, the compression protrusion 21p is a protrusion that protrudes obliquely at an angle α1 with respect to the wall surface 21m of the sipe 21 from the wall surface 21m toward the bottom 21t of the sipe 21. Naturally, the length (free length) L0 when released from the restraint of the compression protrusion 21p is longer than the width W of the sipe 21 and the sipe width of the length of the first sipe 21. The direction component L1 is shorter than the width W of the sipe 21. Since L1 is in the relationship of the free length L0 and L1 = L0sinα1, the other end 21v of the compression protrusion 21p is in contact with the wall surface 21n while being compressed in the tire circumferential direction by the wall surface 21n. The above L1 needs to be in a range satisfying the relationship represented by L1 <W <L1 / sinα1.
Further, when the α1 is 90 ° or more, the compression protrusion 21p is not compressed in the tire circumferential direction, so the α1 needs to be less than 90 °. Furthermore, if the α1 is small, not only the free end L0 has to be lengthened in order to make the compression projection 21p compressed in the tire circumferential direction, but also when the contact is made with the wall surface 21n. Since the bending of the compression protrusion 21p becomes large, it becomes difficult to sufficiently suppress the collapse deformation of the block 20. As a result of examination by the inventors, it was found that 45 ° is appropriate as the lower limit value of α1.
Therefore, in order to form the sipe 21 having the compression protrusion 21p, it is necessary to design a blade for sipe formation so as to satisfy the above conditions.

Next, a blade forming the sipe 21 provided with the compression protrusion 21p will be described.
FIGS. 5A and 5B are a perspective view and a cross-sectional view showing the shape of the blade 30 for forming the sipe 21 on the block 20. The blade 30 is made of a thin metal plate and is not shown. When arranged on the inner surface of the metal mold, the plate surfaces 30a and 30b parallel to each other are arranged so as to be orthogonal to the tire circumferential direction. Reference numerals 30c and 30d are side surfaces of the blade 30 in the height direction (perpendicular to the blade installation surface). As shown in FIG. 5C, the side surface 30d side is the bone portion of the vulcanization mold 40 (see FIG. 1). It is attached to the bottom part 42c of the groove part 42 for forming the block 20 in the tread 11 surrounded by the shown circumferential groove 12 and the protrusion part 41 for forming the lateral groove 13). Hereinafter, the side surface 30c is referred to as an upper surface, the side surface 30d is referred to as a lower surface, the upper surface 30c side is referred to as an upper side of the blade 30, and the lower surface 30d side is referred to as a lower side. Further, the side surface indicated by reference numeral 30k is simply referred to as a side surface.
The plate surface 30a is formed with a cut 30p extending in a direction orthogonal to the side surface 30k (a direction parallel to the tire width direction when installed in the vulcanization mold). The cut 30p is inclined obliquely upward with respect to the thickness direction from the surface of the plate surface 30a. Hereinafter, this cut 30p is referred to as an oblique cut.
Here, the thickness of the blade 30 is W, the depth of cut of the oblique cut 30p (the blade thickness direction component of the length L0 in the extension direction of the oblique cut 30p) is L1, and the oblique cut 30p and the plate surface 30a. L1 = L0sinα1, where α1 is the angle formed by
Since the blade 30 is for forming the compression protrusion 21p, the L0 is made thicker than the thickness W of the blade 30, and the L1 is made shorter than the thickness W of the blade 30. Yes. That is, L0 and L1 are set so as to satisfy the relationship represented by L1 <W <L1 / sinα1. In addition, the range of α1 is preferably 45 ° ≦ α1 <90 °, similarly to the condition of the compression protrusion 21p described above.

When the pneumatic tire 10 of this example shown in FIG. 1 is manufactured, the blade 30 is disposed on the bottom 42c of the groove 42 of the vulcanizing mold 40 as shown in FIG. As an arrangement method of the blade 30, for example, the lower surface 30d side of the blade 30 may be implanted into a blade implantation groove 42d formed in the bottom portion 42c and extending in the tire width direction. The raw tire (not shown) is vulcanized using the vulcanization mold 40. Thereafter, when the blade 30 is pulled out from the vulcanized tire, the pneumatic tire 10 including the block 20 in which the sipe 21 having the compression protrusions 21p is formed can be obtained.
6 (a) to 6 (c) are diagrams schematically showing a deformation state of the compression protrusion 21p at the time of drawing, and at the time of vulcanization, as shown in FIG. The cut 30p is filled with unvulcanized tread rubber 23. When the vulcanization is completed, the tire in which a large number of blocks 20 are formed by the vulcanization process is taken out from the vulcanization mold 40. At this time, the blade 30 is also pulled out from the block 20 at the same time. The compression protrusion 21p is elastic because it is constituted by the tread rubber 23 that has entered the oblique cut 30p. Therefore, as shown in FIG. 6B, when the blade 30 is pulled out, the other end 21v of the block 20 is pressed against the wall surface 21m integrated with the compression protrusion 21p. As shown in FIG. 6C, when the blade 30 is completely pulled out from the block 20, the compression projection 21p is in a state when vulcanization is completed, that is, the wall surface of the sipe 21 shown by a broken line in FIG. An attempt is made to return to a state where the projection protrudes from 21 m toward the bottom 21 t. However, as described above, since the length L0 of the oblique cut 30p is formed to be larger than the width of the blade 30, the natural length of the compression protrusion 21p is longer than the width of the sipe 21. Therefore, the compression protrusion 21p contacts the other wall surface 21n in a state where the other end 21v is constrained by the other wall surface 21n, that is, in a state compressed by the other wall surface 21n in the tire circumferential direction.
Thus, by using the blade 30 shown in FIG. 5, the block 20 in which the sipe 21 having the compression protrusion 21p shown in FIG. 1 is formed can be obtained.

By the way, as described above, when the compression protrusion 21p is brought into contact with the other wall surface 21n by pulling out the blade 30, the contact position of the compression protrusion 21p may vary. Therefore, as shown in FIGS. 7A and 7B, in addition to the compression protrusion 21p, an auxiliary protrusion 21q that abuts the surface of the compression protrusion 21p on the bottom 21t side of the sipe 21 is provided. If the position of the surface of the protrusion 21p on the bottom 21t side is regulated, the auxiliary protrusion 21q functions as a stopper when the compression protrusion 21p moves to the bottom 21t side of the sipe 21, so that the compression protrusion The 21p contact position can be stabilized. Further, this can reduce variations in the magnitude of the compressive force in the tire circumferential direction acting on the compression protrusion 21p, and the sipe 21 of the compression protrusion 21p when the longitudinal force is input to the block 20 can be reduced. Since the deformation toward the bottom 21t can be suppressed, the collapse of the block can be more effectively suppressed.
The auxiliary protrusion 21q is a protrusion protruding in the direction of the wall surface 21m from the wall surface opposite to the wall surface 21m on which the compression protrusion 21p is provided, and is perpendicular to the wall surface 21n (angle α2 in FIG. 7B). Projecting at 90 °), the compression projection 21p is supported from the surface 20s side of the block 20. The length L2 of the auxiliary projection 21q is preferably formed so as to satisfy the relationship of L1 + L2 ≦ W with the width W of the sipe 21 and the length component L1 of the compression projection 21p in the sipe width direction. . This is because if the value of L1 + L2 exceeds W, the compression protrusion 21p is difficult to pull out.
Further, in order to form the sipe 21 having the compression protrusions 21p and the auxiliary protrusions 21q, as shown in FIG. 7C, a plate surface opposite to the plate surface 30a on which the oblique cuts 30p are formed. What is necessary is just to provide the 2nd cut 30q cut in 30b so that it might orthogonally cross with respect to the surface of the said plate | board surface 30b. Also in this case, when the depth of cut of the oblique cut 30p is L1, and the depth of cut of the second cut 30q is L2, the second cut 30q is formed so as to satisfy the relationship L1 + L2 ≦ W.

As described above, according to the best mode, the blade 30 provided with the oblique cuts 30p extending in the thickness direction of the thin metal plate and inclined with respect to the thickness direction is provided on the bottom portion 42c of the groove portion 42. The slant cut 30p is set so that the cut direction of the slant cut 30p is obliquely upward when the bottom portion 42c is on the lower side, and the extension direction of the slant cut 30p is parallel to the tire width direction. By vulcanizing the tire using the vulcanizing mold 40, one end 21u is integrated with the wall surface 21m of the sipe 21, and the other end 21v is formed in the tire circumferential direction by the wall surface 21n opposed to the wall surface 21m of the sipe 21. The pneumatic tire 10 including the block 20 provided with the sipe 21 having the compression projection 21p that contacts the wall surface 21n in a compressed state is manufactured. In, excellent in drainage performance can be obtained by effectively suppress deformation dent collapse of the block 20, a pneumatic tire 10 which can improve the running stability performance of the vehicle in the low μ road road.
Further, when the angle formed by the oblique cut 30p and the plate surface 30a of the blade 30 is α1, the thickness of the blade 30 is W, and the cut depth of the cut 30p is L1, the L1 is L1 <W <. If the range of L1 / sinα1 is set and α1 is 45 ° ≦ α1 <90 °, the other wall surface 21n protrudes from the wall surface 21m of the sipe 21 and is compressed in the tire circumferential direction by the other wall surface 21n. The compression protrusion 21p which contacts can be provided reliably.
Further, an auxiliary projection 21q that projects in the direction of the wall surface 21m from the wall surface on the side opposite to the wall surface 21m on which the compression projection 21p is provided is provided to regulate the position of the surface on the sipe bottom 21t side of the compression projection 21p. If it does in this way, since the contact position of the said compression protrusion 21p can be stabilized, the collapse deformation of a block can be suppressed still more effectively.

In the best mode, the sipe 21 is a two-dimensional sipe having a straight shape in the depth direction. However, the cross-sectional shape shown in FIG. 8A is a polygonal line and is perpendicular to the plate surface 30s. If a blade 30A provided with an oblique cut 30P similar to the oblique cut 30p is used in any direction, a block 20A having a three-dimensional sipe 21A having a compression protrusion 21P as shown in FIG. The provided pneumatic tire can be manufactured.
Further, as shown in FIG. 9A, if a blade 30B provided with a second notch 30Q similar to the second notch 30q in addition to the oblique notch 30P is used, FIG. As shown, a pneumatic tire including a block 20B in which a three-dimensional sipe 21B having a compression protrusion 21P and an auxiliary protrusion 21Q is formed can be manufactured.
In this way, when the cross-sectional shape is a polygonal line like the blades 30A and 30B, the thickness of the blades 30A and 30B indicates the thickness D in the direction perpendicular to the plate surface 30s of the blades 30A and 30B. The direction perpendicular to the side surfaces 30K of the blades 30A and 30B, which is parallel to the tire width direction, indicates the extending direction of the plate surface 30s. Further, in the blade 30A and the blade 30B, as in the blade 30 shown in FIG. 5, the lower surface 30D side of the blade indicated by reference numeral 30D in FIGS. 8A and 9A is a vulcanization mold (not shown). It is planted at the bottom of the provided groove.
In the above example, the number of the sipes 21 is two, but the number of sipes is not limited to this, and may be one or three or more.

表１から明らかなように、本発明１，２のタイヤは、従来品１，２のタイヤに比較して、氷上性能が優れていることが確認された。また、圧縮突起と補助突起とを備えたサイプを有する本発明２のタイヤの方が、圧縮突起のみを備えたサイプを有する本発明１のタイヤよりも氷上性能が向上していることから、補助突起を設けることにより本発明の効果を更に高めることができることが確認された。 In order to confirm the effect of the present invention, a tire having a block in which the conventional two-dimensional sipe shown in FIG. 10A is formed (tire of the conventional example 1) and a conventional three-dimensional shown in FIG. A tire having a block in which a sipe is formed (tire of Conventional Example 2) and a tire having a block in which a sipe having a protrusion according to the present invention is formed (tires of the present invention 1 and 2) are prepared. Each tire was mounted on a test vehicle, a braking test was conducted on an icy road, and the performance on ice of each tire was compared. The results are shown in Table 1 below. The sipe of the present invention 1 is a three-dimensional sipe having only the compression protrusion 21P shown in FIG. 8B, and the sipe of the present invention 2 is the compression protrusion 21P and auxiliary protrusion 21Q shown in FIG. 9B. And a sipe. Moreover, the size of the tire used for the test is 195 / 65R15, and the tire internal pressure is 200 kPa.
In the running test, the braking distance from the initial speed of 40 km / h until the vehicle was brought into a stationary state by applying a brake was measured. Then, the average deceleration was calculated from the braking distance and the initial speed, and the magnitude of the average deceleration was expressed by an index with the average deceleration magnitude of the tire of Conventional Example 1 being 100, and the performance on ice was evaluated. . The higher the index, the better the performance on ice.

As is clear from Table 1, it was confirmed that the tires of the present inventions 1 and 2 were superior in performance on ice compared to the conventional products 1 and 2. Further, the tire of the present invention 2 having a sipe having a compression protrusion and an auxiliary protrusion has improved performance on ice than the tire of the present invention 1 having a sipe having only a compression protrusion. It was confirmed that the effects of the present invention can be further enhanced by providing the protrusions.

  As described above, according to the present invention, the drainage performance is ensured, and even when the input front-rear force is small, the collapse of the block can be effectively suppressed, so that the running stability performance of the vehicle on the low μ road surface can be improved. Can be improved.

It is a development view showing a tread pattern of a pneumatic tire according to the best mode of the present invention. It is a perspective view of the block provided with the sipe of this invention which concerns on this best form. It is a figure for demonstrating the compression protrusion which concerns on this best form. It is a figure for demonstrating operation | movement of the pneumatic tire which concerns on this best form. It is a figure which shows the braid | blade for forming the sipe which concerns on this best form. It is a figure which shows the deformation | transformation state of a compression protrusion when pulling out a braid | blade from a tire. It is a figure which shows the other example (two-dimensional sipe) of the sipe by this invention. It is a figure which shows the other example (three-dimensional sipe) of the sipe by this invention. It is a figure which shows the other example (three-dimensional sipe) of the sipe by this invention. It is a figure which shows the block in which the conventional two-dimensional sipe was formed. It is a figure which shows the block in which the conventional three-dimensional sipe was formed. It is a figure which shows the block in which the conventional sipe with a protrusion was formed.

Explanation of symbols

10 pneumatic tires, 11 treads, 12 circumferential grooves, 13 transverse grooves,
20 blocks, 21, 21a, 21b sipe, 21m, 21n sipe wall,
21p compression protrusion, 21q auxiliary protrusion, 21t bottom of sipe,
21u one end of the protrusion (fixed end), 21v the other end of the protrusion (free end),
22a-22c small block, 30 blades, 30a, 30b plate surface,
30p diagonal cut, 30q second cut, 40 vulcanization mold, 41 bone,
42 Groove.

Claims (7)

  A plurality of main grooves provided on the tread surface of the tire so as to extend along the circumferential direction of the tire, and a plurality of sub-grooves provided on the tread surface of the tire so as to extend along the width direction of the tire; In the pneumatic tire provided with a plurality of blocks partitioned by the main groove and the sub-groove, a sipe extending in the tire width direction is formed in the block, and one wall surface of the sipe Compressed with a free length longer than the width of the sipe, protruding toward the other wall surface facing the one wall surface and contacting the other wall surface while being compressed in the tire circumferential direction by the other wall surface A pneumatic tire comprising a protrusion.   The said sipe is further provided with the auxiliary | assistant protrusion which protrudes toward the said one wall surface from the said other wall surface, and contact | abuts the surface of the bottom part side of the said sipe of the said compression protrusion. Pneumatic tire.   A blade for forming a width sipe extending in the tire width direction on the tread surface of the block, which is installed in a groove for forming a block provided in the vulcanization mold, and in the thickness direction of the plate surface An incision extending in the tire width direction is formed in the incision, and the incision extends in an oblique direction toward the bottom of the groove when the blade is installed in the groove, and the length is A sipe forming blade characterized by being longer than the width of the sipe.   An angle α1 formed by a surface of the blade where the cut is provided and an extension direction of the cut is in a range of 45 ° ≦ α1 <90 °, the thickness of the blade is W, and the length of the cut The sipe forming blade according to claim 3, wherein when the component in the thickness direction of the blade is L1, the L1 is in a range satisfying a relationship of L1 <W <L1 / sinα1.   5. The sipe forming blade according to claim 4, wherein a second notch perpendicular to the plate surface of the blade is formed on a side opposite to the notch of the blade.   6. The sipe forming blade according to claim 5, wherein when the length of the second cut is L2, the L2 is in a range satisfying a relationship of L1 + L2 ≦ W.   The sipe forming blade according to any one of claims 3 to 6 is disposed at a bottom of the groove of a vulcanization mold having a groove for forming a block on a tread surface, and the tire is added. After the vulcanization treatment, the blade is pulled out from the vulcanized tire to form a plurality of blocks in which a sipe in the width direction is formed on the tread surface of the tire, and the compression is applied to one wall surface of the sipe. A method for manufacturing a pneumatic tire, characterized in that the protrusion or the compression protrusion and the auxiliary protrusion are formed.

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