JPH10129218A - Pneumatic tire, and vulcanizing die used in its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of the eccentric wear by forming one side of a siping wall surface to be mostly recessed, and forming the other wall surface to be a projected surface to be fitted to the recessed surface. SOLUTION: Sipings 11-15 are notched in the radial direction of a tire, and extended in the tread width direction as a trend. In such a tread pattern, the respective sipings 11-15, especially the shoulder siping 11, the side part siping 14, and the center part siping 15, one of the siping wall surfaces located opposite to each other are mostly formed to be recessed to the imaginary plane in the radial direction, and the other siping wall surfaces are the projected surface to be fitted to the recessed surface. Because the forming part of the recessed surface and the projected surface of the siping wall surface opposite to each other occupies most part, the projected surface is sufficiently, smoothly, and surely fitted to the recessed surface, and effective restricted by raised parts to be leaned against each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a tread land portion,
In many cases, a block is provided with a plurality of sipes which are cut in the tire radial direction and extend in the tread width direction, and exhibit excellent wet performance, performance on ice, etc. and a pneumatic tire used for manufacturing the tire. It relates to a metal mold.

[0002]

2. Description of the Related Art When a sipe is formed in a land portion of a tread, for example, a block, the rigidity of a block portion divided by the sipe is inevitably reduced as compared with a case where no sipe is provided. Therefore, uneven wear such as heel and toe wear is apt to occur. Therefore, in order to control the occurrence of such uneven wear, for example, as disclosed in Japanese Patent Application Laid-Open No. 5-58118, a block is formed. A technology has been proposed in which a convex portion is formed on one wall surface of a sipe extending in the tire width direction, and a dimple meshing with the convex portion is formed on the other wall surface. , Based on the engagement between the convex portion and the dimple,
Since each sub-block divided by the sipe regulates the fall of each other, the amount of fall can be reduced, the braking distance when braking on icy road surface can be shortened, and on dry road surface, It is assumed that heel and toe wear can be controlled.

[0003]

In the prior art, however, since the projections and dimples formed on the wall of the sipe are small in size, it is difficult to always reliably engage them with each other. There is a high possibility that the expected effect cannot be obtained, and when the braking force acts on the tire, the convex portion p of each sipe wall and the dimple d mesh with each other as illustrated in FIG. When the falling of the respective sub-blocks sb is mutually restrained by each other, as shown in FIG. 5 (b), when the driving force acts on the tire, the engagement of both of them is loosened. By each sub-block s
Since the falling restraint force of b becomes small, there is a problem that occurrence of uneven wear to the action of the driving force is inevitable.

[0004] The present invention has been made as a result of studying to solve such problems of the prior art, and its object is to be made regardless of whether braking or driving. Provided are a pneumatic tire capable of always preventing falling deformation of a land portion divided by a sipe and effectively preventing occurrence of uneven wear, and a vulcanizing mold used for manufacturing the tire. It is in.

[0005]

A pneumatic tire according to the present invention comprises a plurality of sipes formed in a tread land portion by cutting in a radial direction of the tire and tending to extend in a tread width direction. One of the sipe wall surfaces opposed to each other is, for the most part, a concave surface with respect to the virtual imaginary plane, and the other sipe wall surface is a convex surface fitted into the concave surface.

In this pneumatic tire, each of the concave surface and the convex surface is formed over most of the sipe wall surface, and their respective dimensions are much larger than those in the prior art. Will be performed smoothly and reliably, and even if the convex top does not exactly correspond to the concave valley in the fitting, the convex top will have any of the concave surfaces. Because of the abutment of these parts, the falling deformation of each land part divided by the sipe is sufficiently restrained by their mutual leaning, which means that when the braking force is applied during the rolling load of the tire The same applies to the case where the driving force is applied, and the occurrence of uneven wear can be effectively prevented.

Further, the vulcanizing mold of the present invention forms a sipe protruding radially inward on a molding surface of a tread land portion and extending in the tread land portion in a tendency to extend in the tread width direction. Each blade is provided with a curved portion or a bent portion protruding to one side with respect to the imaginary surface in the radial direction over most of the blades.

According to this vulcanizing mold, a sipe having a concave surface and a convex surface over most of the wall surface of the sipe can be easily and easily formed under the action of a curved portion or a bent portion of the blade. It can be formed exactly as expected. Further, since the blade here has a curved portion or a bent portion extending over most of the blade, the depth of the concave surface of the sipe wall surface and the height of the convex surface can be made sufficiently large, while, on the other hand, The slope of the curved portion or the bent portion with respect to the virtual imaginary surface in the radial direction can be made sufficiently small, so that the vulcanized tire can be easily and smoothly taken out of the mold.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing one embodiment of the present invention. FIG. 1 (a) is a development view of a tread pattern, and FIG. 1 (b) is bb in FIG. 1 (a).
The sectional views along the line are shown. The illustrated tread pattern is provided with two circumferential main grooves 1, 1 extending continuously in the circumferential direction at a tread central portion, and at positions lateral to the respective circumferential main grooves 1, 1. Tread tread 2
Are provided in the center section 3 and the side sections 4, respectively.
And from the circumferential auxiliary groove 5 to the circumferential main groove side,
In the figure, an inclined groove 7 which extends diagonally downward and ends without reaching the circumferential main groove 1 and a portion lateral to the circumferential narrow groove 6 is curved so as to be slightly convex upward in the figure and the tread end. The shoulder sipe 11 which is located between each of the lateral grooves 8 of the tread tread portion 2 and between the lateral grooves 8 and has the same curved tendency as that of the shoulder sipe 11, Each of the buttress sipes 12 is formed on one imaginary curve with a slight separation in the tread width direction, and at the same time, from the circumferential edge of each lateral groove 8 on the circumferential narrow groove side to the circumferential main groove 1. In between, this also extends with the same curved tendency as the lateral groove 8, and the micro sipes 13 located between the lateral groove edge and the circumferential narrow groove 6, and the small sipes 13 between the circumferential narrow groove 6 and the circumferential sub-groove 5. Side area sipe 14 located between, and
Each of the central region sipes 15 located between the circumferential sub-groove 5 and the circumferential main groove 1 is positioned on one imaginary curve continuous with the lateral groove 8.

Here, each of the sipes 11 to 15 is cut in the radial direction of the tire and tends to extend in the tread width direction. In such a tread pattern, for each of the sipes 11 to 15, especially the shoulder sipes 11, the side region sipes 14, and the central region sipes 15, one of the sipe wall surfaces opposed to each other is mostly used. , A concave surface with respect to the virtual virtual surface in the radial direction, and the other sipe wall surface is a convex surface fitted into the concave surface. FIG. 1 (b) is a radial cross-sectional view showing the above by taking the shoulder sipe 11 as an example. Here, one of the sipe wall surfaces 11a is almost entirely recessed with respect to the radial virtual plane XX. And the other sipe wall surface 11b is a convex surface that fits into the concave surface.

Here, in plan view of the sipe 11,
The amount of deviation of the concave surface and the convex surface from the virtual imaginary surface XX in the radial direction is represented by a sipe as shown by a broken line in FIG.
In addition to the maximum at the center in the longitudinal direction and the minimum at its end, the shoulder sipe 11
If one end ends on land, as in
However, in the vicinity of the terminal end in the land, the rigidity of the land part divided by the sipe 11 does not decrease so much. Therefore, the land part is accompanied by the fitting of the convex surface into the concave surface. Needless to say, there is no possibility that the sipe 11 is greatly deformed by falling down.
Can be maximized at the opening end of the sipe 11 to the circumferential narrow groove 6 or in the vicinity thereof.

When each sipe is configured in this way, the formation area of the concave surface and the convex surface of the mutually facing sipe wall surface extends over most of the respective sipe wall surfaces. Is sufficiently smoothly and securely performed, and when the tire is rolling, the falling deformation of the land portion divided by the sipe is based on the fitting described above. Since it is effectively restrained by the leaning, the occurrence of uneven wear such as heel and toe wear on each land portion is effectively prevented. This is substantially the same even when the convex top is in contact with a position other than the valley of the concave surface.

FIG. 2 illustrates this by using the shoulder sipe 11.
FIG. 2 is a cross-sectional view in the tire radial direction, showing that when a braking force is applied to the tire, FIG.
As shown in (a), the convex surfaces are fitted into the recessed surfaces of the sipe wall surfaces 11a and 11b, and the two land surfaces 17a and 11b are brought into close contact with each other. The deformation is effectively restrained, and when a driving force acts on the tire, as shown in FIG. 2B, the concave surface and the convex surface are wide, especially in the deep portion of the sipe 11. By fitting over the area and providing a substantial reduction in sipe depth, the collapse of the respective land sections 17 will be sufficiently constrained by their mutual backlash as well, so that Uneven wear of the tread land portion can be effectively prevented for both power and driving force.

In manufacturing the pneumatic tire as described above, FIG. 3 is a partially cutaway perspective view in which a main part is enlarged. On the forming surface 21, a metal blade 22 for sipe formation protrudes radially inward, upward in the figure,
For the blade 22, it is preferable to use a vulcanizing mold provided with a curved portion or a bent portion that protrudes on one side with respect to the virtual imaginary surface 23 over the majority of the blade, and a curved portion 24 in the drawing. It is.

Here, since the metal blade 22 is made of a thin plate material, as described above, when the curved portion 24 that is convex on one side is formed, its convex side surface and concave side are formed. The surface has a shape corresponding to the surface, and the convex surface contributes to the formation of the concave surface on the sipe wall surface, and the concave surface contributes to the formation of the convex surface.

Accordingly, when vulcanization molding of a pneumatic tire is performed by using such a vulcanization mold, a tread land portion is formed by the molding surface 21, and as shown by a virtual line in the figure. Grooves continuous in the circumferential direction are formed by the protrusions 25, and the inclined grooves 7 and the lateral grooves 8 are formed by protrusions (not shown), respectively, and the sipe and the depression of the sipe wall are formed by the metal blade 22. The faces and convexities will be formed simply and easily and exactly as expected.

In addition, the curved portion 24 here is a blade
Since it is formed over most of the area 22, the depth of the concave surface and the height of the convex surface can be appropriately increased as required. The slope of each of the concave side and the convex side of the surface 24 with respect to the virtual imaginary plane 23 is sufficiently reduced, so that the vulcanized tire can be easily and smoothly removed from the mold.

By the way, the shape and size of the curved portion or bent portion of the metal blade 22 can also be appropriately selected as required. For example, FIGS.
It is also possible to use one as shown in a cross-sectional view seen from each of the AA direction and the BB direction in FIG.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the pneumatic tire having the tread pattern shown in FIG. 1 using the vulcanizing mold shown in FIG. In addition, here, shoulder sipe 11, width 10mm,
A metal blade 22 having a protrusion of 5.4 mm from the molding surface 21 was used, and the protrusion of the curved portion 24 of the blade 22 was 1.5 mm. Set the tire size to 205/65 R15, attach it to the 6 1/2 rim, fill the specified internal pressure, and measure the heel and toe abrasion after 10,000km running on a real car using a domestic sedan. As a result of index evaluation, the uneven wear resistance index was as shown in Table 1. In addition, this index evaluation performed the comparative tire manufactured without forming a curved part and a bent part in a blade as control. The conventional tires in the table are the tires described as prior art in this specification, and have one small-sized convex portion on one sipe wall surface and the convex portion on the other sipe wall surface. This is a tire provided with one small-sized dimple that meshes.

[0020]

[Table 1]

According to the above Table 1, the inventive tire is not only used for the comparative tire but also for the conventional tire.
It is clear that the uneven wear resistance performance can be greatly improved.

[0022]

As is clear from the above description, according to the pneumatic tire of the present invention, the falling deformation of the land portion divided by the sipe can be effectively performed regardless of the time of braking and the time of driving. By restraining, it is possible to sufficiently prevent the occurrence of uneven wear on the land portions. Further, according to the vulcanization mold of the present invention, the formation of the concave surface and the convex surface on the sipe wall surface can be performed simply and easily, and accurately as expected. The height of the convex and the convex surface can be appropriately selected as required, and the vulcanized tire can be smoothly and easily taken out of the mold.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a modified example of a land portion.

FIG. 3 is an enlarged partial cross-sectional perspective view showing a main part of a vulcanizing mold.

FIG. 4 is a diagram illustrating a cross-sectional shape of a blade.

FIG. 5 is a cross-sectional view illustrating a modification of a land portion of a conventional tire.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circumferential main groove 2 Tread tread 3 Central area 4 Side area 5 Circumferential sub-groove 6 Circumferential narrow groove 7 Inclined groove 8 Horizontal groove 11 Shoulder sipes 11a, 11b Sipe wall surface 12 Buttress sipes 13 Micro sipes 14 Side sipes 15 Central sipe 17 Land part 21 Forming surface 22 Metal blade 23, XX Radial imaginary surface 24 Curved part 25 Ridge

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 105: 24 B29L 30:00

Claims (2)

[Claims] 1. A pneumatic tire having a plurality of sipes cut into a tread land portion in a tire radial direction and tending to extend in a tread width direction, wherein the sipe wall surfaces are opposed to each other. A pneumatic tire having, as a major part thereof, a concave surface with respect to the virtual virtual surface in the radial direction, and the other sipe wall surface as a convex surface fitted into the concave surface. 2. A tread land having a plurality of blades projecting radially inward from a molding surface thereof to form a sipe extending in the tread width direction on the tread land. A vulcanizing mold comprising a blade and a curved portion or a bent portion protruding to one side with respect to a virtual imaginary surface in a radial direction over most of the blades.