JP3517721B2 - Pneumatic tire and tire sipe forming piece structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having sipes formed on land portions such as blocks and ribs of a tread tread, and a sipe forming piece structure for manufacturing the tire.

[0002]

2. Description of the Related Art Conventionally, a tread tread has a block defined by a main groove in the tire circumferential direction and a groove in the tire width direction, or is defined by a circumferential groove. In a pneumatic tire having a land portion such as a rib, in order to improve braking performance and traction performance especially when traveling on an ice and snowy road, one or a plurality of tires generally extending mainly in the tire width direction are provided in the land portion such as a block. A thin kerf called a sipe (which is called a sipe in the present invention) is provided.

However, when a sipe is formed on the land, the edge effect improves the traction, but the rigidity of the land such as blocks and ribs is unavoidably deteriorated, and the wear resistance is poor and uneven wear occurs. It tends to occur.

Therefore, as shown in FIG. 14 (A) and FIG. 14 (B), the sipes (50) are partially made shallow so that the bottom side of the sipes is partially cut off in a sipe shape considering the rigidity of the land portion. It was common. (51) indicates a missing portion.

In this case, since the sipes (50) are partially missing, the sipe edge length is reduced due to the wear of the land portion such as the block, and as a result, the traction property due to the edge effect is deteriorated. There's a problem.

Therefore, in order to secure the rigidity of the land portion of the block or the like and the sipe edge length over a long period of time, for example,
As shown in FIG. 14C, at least the bottom end side in the depth direction of the sipe (50) is curved in a wavy shape (Japanese Patent Laid-Open No. 4-3).
72406), or as shown in FIG.
A sipe (50) formed in a zigzag shape or a wavy shape in the depth direction (JP-A-4-306106).
Is proposed. Further, there is also proposed a structure in which the bottom portion in the sipe depth direction is enlarged (Japanese Patent Laid-Open No. 5-254314).

However, when a braking force or a driving force is applied to the tire, the groove width of the sipe increases, so that the sipe cross section is changed in the sipe depth direction as described above. If so, Fig. 14 (A)
It is impossible to obtain the same level of rigidity and effect as in the case of the sipe shape in which a part is missing as in (B).

Further, there is also proposed a sipe whose bottom side is formed into a bifurcated shape (Japanese Patent Laid-Open No. 2-227306).

In this case, although the sipe edge increases as the land rigidity is secured and the tire wear progresses, the manufacturing cost of the sipe itself becomes high, and the tire vulcanization molding die after tire molding is used. The mold release resistance is large, the rubber forming the tire design surface is easily damaged, and the sipe groove width is small on the sipe bottom side, and sipe cracks are likely to occur from the bottom.

In particular, in order to avoid a decrease in the rigidity of the land portion due to the sipes, it is most effective to make the land portions on both sides of the sipes continuous by partially omitting the sipes as shown in FIGS. 14 (A) and 14 (B). is there.

On the other hand, for tires such as studless tires that have to increase the number of sipes set, how to secure the rigidity of land parts such as blocks to increase the number of sipes,
Securing the sipe length can be an index for performance improvement.

Therefore, it is desired to suppress the decrease in the sipe length due to the progress of wear of the tire and to have a shape capable of ensuring rigidity equivalent to that of the missing shape.

The present invention has been made in view of the above, and by devising the sipe shape of the land portion of the block or the like, the land portion rigidity and wear of the block or the like, which was conventionally considered to be a transgressive event, are reduced. It is possible to prevent a decrease in traction due to the above, it is possible to achieve both of these performances simultaneously, and it is possible to increase the number of sipes set, especially a pneumatic tire that can be suitably used for studless tires and the like, And a sipe forming piece structure for tire manufacturing.

[0014]

The present invention is to solve the above-mentioned problems, and a pneumatic tire according to a first aspect of the present invention has a main groove extending in the tire circumferential direction on the tread surface of the tire. A pneumatic tire having land portions such as blocks and ribs defined by grooves in the tire width direction and having sipe formed on each land portion, and at least one sipe of each land portion is deep. In the bottom side area in the depth direction, it is divided into multiple parts at required locations in the sipe length direction,
Corner of the divided part in the divided side of the sipe
Side is it obliquely triangular to sipe sideward to wider bottom the divided intervals without reducing the sipe bottom length of
Flip bent, characterized in that the land portion of the sipe sides is continuous with the cutting portion.

According to this pneumatic tire, the sipe in each land portion such as a block is divided on the bottom side, and the land portions on both sides of the sipe are continuous at the divided portion. As a result, the rigidity of the land portion in the direction orthogonal to the sipe can be secured as in the case of the sipe partially lacking.

[0016] Moreover, it sheds sipe bottom portion, since the bent thread obliquely to the side without reducing the sipe bottom length, the sipe length even wear of the tire progresses be reduced almost Therefore, it is possible to prevent the sipe edge effect, that is, the deterioration of traction.

According to a second aspect of the present invention, there is provided a sipe forming piece used for manufacturing the tire, particularly a thin plate-like sipe forming piece attached to an inner surface of a tread mold portion of a tire manufacturing mold. In the part where the sipe bottom side region of the piece is formed, the sipe bottom side forming part is formed by dividing the sipe bottom side region into a plurality of parts at a required position in the longitudinal direction by thin cut
The side of the corner portion of the divided position, characterized by comprising bent screw obliquely triangular laterally so as to widen the cutting gap as the bottom end side of the.

According to this sipe forming piece, by attaching it to the inner surface of the tread mold portion of the tire manufacturing mold, in particular, the portion corresponding to the land portion such as the block or rib,
The sipe having the above configuration can be formed on the land portion of the tire to be vulcanized and molded.

[0019] Moreover, the sipe forming member is divided formed by a thin cut part of the sheet-shaped sipe forming member, min
Of the corner of the part where the sipe bottom side was cut off
Side, and it is only bending screw obliquely triangular laterally, not costly an easy manufacture of the sipe.

In the above-mentioned structure of the sipe forming piece, as in claim 3, in the divided sipe bottom side forming portion .
Tilt both sides of the dividing point diagonally to the opposite side.
It is better to bend it.

That is, by forming in this way, it is possible to reduce the bending amount of both sipe bottom side forming portions and to set the dividing interval large. In other words, a small amount of bending can hold a sufficient distance. Further, since the amount of lateral extension of the sipe bottom side formation portion can be small, the resistance at the time of releasing from the mold during vulcanization molding of the tire is not affected by the bending as described above. Get smaller.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a partial schematic development view showing a tread pattern of a pneumatic tire according to the present invention, FIG. 2 is an enlarged perspective view of one land portion (block), and FIG. 3 is a sipe bottom portion. FIG. 4 is a lateral cross-sectional view, and FIG. 4 is an enlarged perspective view and a plan view showing the sipe shape. FIG. 5 shows a processed state of the sipe forming piece.

In the pattern of FIG. 1, (1) is a main groove formed as a longitudinal groove in the tire circumferential direction on the tread surface.
(2) is a groove in the tire width direction that intersects with the main groove (1), and these define a large number of blocks (3) as land portions. In addition, although not shown,
There is also a pattern in which ribs that are continuous in the circumferential direction are used alone or in combination with blocks as land portions instead of blocks.

The block (3) is provided with one or a plurality of sipes (5), which are narrow cut grooves extending mainly in the tire width direction, at a predetermined depth. The sipes (5) may be provided at one or both side ends of the block (3) as shown in the figure, or may be provided at the side ends without being opened. The groove width of this sipe (5) is usually 0.1 to 2.0 mm, preferably 0.5 to
It is 1.5 mm. The sipes (5) are not limited to those in the tire width direction, but may be provided in the tire circumferential direction or diagonal direction.

At least 1 in said block (3)
The sipe (5) of the book is divided into left and right portions at the substantially central portion in the length direction of the sipe in the region of the substantially half portion on the bottom side in the depth direction, and the sipe bottoms on both sides are divided as shown in the figure. The sides of the corners of the dividing points in the side portions (5a) and (5b) are triangular toward the sides of the sipe so that the dividing interval (S) becomes wider toward the bottom without substantially reducing the total length of the sipe. the <br/> are twisted at an angle, the sipes on both sides (typically, front and rear tire running direction) in a state in which the land portion (3a) (3b) are continuous at the dividing portion (6) of the.

Therefore, the land portions (3a) (3b) on both sides
The behavior of the vehicle during traveling is mutually regulated by the action of the continuous portion (6), and the decrease in the rigidity of the land portion in the direction orthogonal to the sipe (5) (white arrow in FIG. 2) is suppressed. It is possible to secure the same rigidity as in the case of a sipe shape with a part missing. Further, even if tire wear progresses, the sipe length hardly decreases, so that the sipe edge effect, that is, the traction property does not decrease.

The sipe (5) having the above-mentioned shape is the sipe forming piece (1) attached to the inner surface of the tread mold portion of the tire manufacturing mold.
By using the one having the shape of FIG. 4 as 5),
Can be formed.

The sipe forming piece (15) is processed as follows. In the forming portion of the sipe bottom side region of the thin flat plate-shaped sipe forming piece (15) shown in FIG.
As shown in FIG. 5 (B), an extremely thin (usually less than or equal to) notch (16) was made at the central portion in the length direction so as not to decrease the overall length of the sipe, and it was divided into two parts on the left and right sides and was divided. sipe bottom forming portion of (15a) (15b)
As shown in FIG. 5 (C), the corners of the dividing points are slanted toward the opposite sides of the sipe so that the dividing intervals (S) by the cuts (16) are widened toward the bottom end side. Twist.

This sipe bottom forming portion (15a) (15b)
Screw The bending state, both the sipe bottom forming portion opposite to each other with respect to the cuts (16) as in the figure (15a) (15b)
The corners of the divided position, i.e. is preferably bent screws diagonally side corner in a triangular shape to the side between the cut end and the bottom end of, advance especially twisted so that the cross section forms a slightly curved shape You can also

The length of the sipe bottom formed by both the sipe bottom side forming portions (15a) and (15b) of the sipe forming piece (15) formed as described above is slightly reduced by the gap due to the cut (16). Just by doing, you can secure the same length as the original sipe bottom length.

The length (L) from the bottom end of the notch (16) at the dividing point can be appropriately set according to the tire size and the shape of the land portion such as the block.

By bending the sipe bottom side forming portions (15a) and (15b) on both sides of the dividing point as described above, the sipe bottom is slightly lifted. Therefore, as shown in FIG.
An extension (14) corresponding to the floating dimension is provided at the edge of the bent portion of the flat plate-shaped sipe forming piece (15), and the extension is formed in the bent state. It is preferable that the sipe bottom of the portion has the same depth as the unbent portion. The extension (14) may be formed longer. In this case, the sipe bottom length is further increased.

The sipe forming piece (15) is attached to the inner surface of the tread mold portion of the tire manufacturing mold in the same manner as in the conventional case, and the tire is vulcanized and molded.
The sipe (5) having the above-mentioned shape is formed as shown in FIGS.

As the sipe forming piece (15), as shown in FIG. 7, both sipe bottom side forming portions (15a) (15)
A substantially circular or rounded enlarged portion (17) can be formed at a portion corresponding to the top of the dividing portion by the cut (16) between b). In this case, the bending process is facilitated, and the sipes (5) formed by the bending process are facilitated.
In the above, since there is no rubber edge on the top of the divided portion (6), cracks are less likely to occur.

Further, as shown in FIG. 8, it is possible to round the corners (18) at the dividing points of the sipes bottom side forming portions (15a) and (15b). Also in this case, it is possible to prevent the occurrence of cracks from the corner portion (8) of the bottom end of the sive corresponding to the corner portion (18) of the sipe (5) molded by the sipe forming piece (15).

As shown in FIG. 9, the sipe-forming piece (15) is cut into a plurality of places (12) at required intervals in the lengthwise direction.
It is also possible to provide a dividing point according to, and perform the sipe bottom side forming portions (11a), (11b), and (11c) on both sides of each dividing point by diagonally bending sideways in a triangular shape in the same manner as described above. In this case, the molded sipes (5) are
The bottom is divided into a plurality of parts to form a bent shape.

Further, as shown in FIG. 10, if a thin plate-shaped sipe forming piece (15) is formed with a notch (16) having a substantially T shape, both sipe bottom side forming portions (11a) (11b). It becomes easier to bend sideways.

Furthermore, the sipe forming piece (15) is
The sib bottom side forming portions (11a) and (11b) are bent to opposite sides on both sides of the cut portion by the cut (16), and both bottom side forming portions (11a) and (11a) (11b) are formed as shown in FIG.
It is also possible to bend b) to the same side. In practice, it is preferable to bend the opposite sides so that the amount of bending of the sipe bottom portion can be reduced and the interval between the divided portions can be increased.

The present invention can be constructed by appropriately combining and using the respective embodiments described above. Further, the present invention is not limited to the implementation in the sipe shape having a flat plate shape as shown in the drawing, and as illustrated in FIGS. 12 and 13, for example, in the shape of the conventionally known modified sipe illustrated in FIG. It is also possible to add and implement the structure which combined the division and the bending shape.

In any of these cases, the sipe forming piece (1) is provided by attaching the sipe forming piece (15) to the inner surface of the tread portion of the tire vulcanization molding die.
A sipe (5) corresponding to 5) is formed.

[0042]

As described above, according to the present invention, the bottom side portion of the sipe is divided and formed at a required portion in the length direction of the sipe , and both side portions of the division portion are slanted laterally in a triangular shape. As a bent shape, by connecting the land parts on both sides of the sipe at the divided part, it is possible to prevent both the rigidity of the land part of the block and the like and the decrease of the traction property due to wear. Both performances can be compatible. Moreover, since the rigidity can be secured, it is possible to increase the number of sipes set, which is particularly suitable for studless tires.

[Brief description of drawings]

FIG. 1 is a partial schematic development view showing a tread pattern of a pneumatic tire.

FIG. 2 is an enlarged perspective view of one land portion (block).

FIG. 3 is a transverse cross-sectional view near the bottom of the sipe of the above.

FIG. 4 is an enlarged perspective view (A) and a plan view (B) showing a sipe shape.

5 (A), (B), and (C) are explanatory views of a processed state of the sipe forming piece.

FIG. 6 is a perspective view showing another embodiment of the sipe and the sipe forming piece.

FIG. 7 is a perspective view showing still another embodiment of the sipe and the sipe forming piece.

FIG. 8 is a perspective view showing still another embodiment of the sipe and the sipe forming piece.

FIG. 9 is a perspective view showing still another embodiment of the sipe and the sipe forming piece.

FIG. 10 is a perspective view showing still another embodiment of the sipe and the sipe forming piece.

FIG. 11 is a perspective view (A) and a plan view (B) showing still another embodiment of the sipe and the sipe forming piece.

FIG. 12 is a perspective view showing still another embodiment of the sipe and the sipe forming piece.

FIG. 13 is a perspective view showing still another embodiment of the sipe and the sipe forming piece.

14 (A), (B), (C), and (D) are perspective views showing conventional sipe shapes, respectively.

[Explanation of symbols] (1) Main groove (2) Tire width direction groove (3) Block (3a) (3b) Land parts on both sides of the sipe (5) Sipes (5a) (5b) Sipe bottom side part (6) Divided part (14) Expansion section (15) Sipe forming piece (15a) (15b) Sipe bottom side forming part (16) Notch (17) Extension

Claims (3)

(57) [Claims] 1. A tread surface of a tire has land portions such as blocks and ribs defined by main grooves extending in the tire circumferential direction and grooves in the tire width direction, and sipes are formed on each land portion. In the pneumatic tire, the at least one sipe of each land portion is divided into a plurality of parts at a required position in the length direction of the sipe in the bottom side region in the depth direction, and the sipe bottom side part is divided .
Side is the corner of the divided position, bent screws obliquely to the triangular to sipe sideward to wider bottom the divided intervals without reducing the sipe bottom length, the dividing portion has land portion of the sipe sides A pneumatic tire characterized by being continuous with. 2. A thin plate-shaped sipe-forming piece attached to the inner surface of a tread mold portion of a tire-manufacturing mold, wherein the sipe-bottom-side region of the sipe-forming piece is formed at a required position in the longitudinal direction. Divide into multiple parts by thin cuts, and divide at the part where the sipe bottom side is divided.
Sipe formed piece structure of the tire, characterized in that the side corners of the location, comprising bent screw obliquely triangular laterally so as to widen the cutting gap as the bottom end side. 3. A front of a divided sipe bottom side forming portion .
Both sides of the dividing part are slanted to the opposite side.
Sipe formed piece structure of a tire according to claim 2, bent formed by screws.