JPH1080923A - Pneumatic tire and vulcanizing mold for pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve running performance on an ice and snow road or wet road while preventing irregular wear. SOLUTION: At the time of running on an ice and snow or wet road, sipe grooves 33 tend to be blocked, but since sidewalls of protrusions 35, 36 of one and the other sides bent and protruded in a ridge state are brought into contact with one another to be supported to one another, blocking is suppressed. Since the protrusions 35, 36 formed at the sipe grooves 33 protrude in reverse (both) direction, a rubber volume of a sectional area 34 becomes substantially equal at both sides of the grooves 33. As a result, lateral rigidities become substantially uniform at either sectional area 33 to suppress occurrence of irregular wear.

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 a sipe groove in a tread portion and a vulcanizing mold used for vulcanizing the pneumatic tire.

[0002]

2. Description of the Related Art Generally, in order to improve running performance on ice and snowy roads and wet roads, a large number of narrow sipe grooves (cuts) are formed on a block surface of a tread portion, and a water film is formed by edges of the sipe grooves. In addition to cutting, moisture on the road surface is sucked into the sipe groove. However, when a large number of such sipe grooves are formed in the block, the blocks are finely divided by the sipe grooves, so that the lateral rigidity of the blocks is reduced. As a result, the blocks are greatly deformed during running and the sipe grooves are closed, As a result, there is a problem in that the drainage performance is reduced, and it becomes impossible to sufficiently improve the traveling performance on an ice-snow road or a wet road. Such a tendency is more remarkable in an ice-snow road tire in which foam rubber having low hardness (rigidity) is used in a part of the tread portion.

[0003] In order to solve such a problem, for example, the one described in Japanese Patent Application Laid-Open No. 5-58118 has been proposed. As shown in FIG. 16, each of the sipe grooves 12 formed in the block 11 is provided with a plurality of protrusions 13 bent in a hemispherical shape toward one side. The other side wall 13a having a convex spherical shape and the one side wall 13b having a concave spherical shape are fitted to be separated by the width of the sipe groove 12. As a result, if the block 11 is deformed due to the running of the tire, the other side wall 13a and the one side wall 13b abut on each other at the protruding portion 13 so as to bulge against each other, and the deformation of the block 11 is suppressed.

[0004]

However, in such a conventional pneumatic tire, since each of the protrusions 13 provided in each of the sipe grooves 12 protrudes toward only one side, the sipe There is a case where the volume of the rubber defined by the groove 12 is larger in the partition area 14 located on the other side than the partition area 14 located on one side of the sipe groove 12 under the influence of the protrusion 13, There is a problem that uneven rigidity may occur in the block 11 due to a difference in lateral rigidity depending on the partition region 14.

The present invention provides a pneumatic tire capable of improving running performance on ice and snowy roads and wet roads while suppressing uneven wear, and is used when vulcanizing such a pneumatic tire. An object of the present invention is to provide a vulcanizing mold.

[0006]

SUMMARY OF THE INVENTION Such an object is achieved by a plurality of circumferentially extending main grooves provided on a tread portion and a plurality of sub-grooves intersecting the main grooves. In a pneumatic tire having a block and a sipe groove extending substantially parallel to the sub-groove in any of the blocks, the sipe groove has a width W substantially the same over the entire area of the sipe groove, and By providing both the one-side protruding portion bent and protruding in the groove toward one side and the other-side protruding portion bent and protruding in the groove toward the other side in the groove, the circumferential direction is also provided on the tread portion of the pneumatic tire. A plurality of main bones forming a main groove extending to the main groove and a plurality of sub-bones forming a sub-groove crossing the main groove are provided, and a plurality of blocks are provided on the tread portion surrounded by these main and sub-bones. Formation A vulcanizing mold for a pneumatic tire having a tread forming surface provided with a blade forming a sipe groove extending substantially parallel to the sub-groove in any of the recesses, wherein the blade has substantially the same thickness over the entire area. Achieved by partially bending the blade at a plurality of locations and providing a one-side bent portion protruding in a mountain shape toward one side and another side bent portion protruding in a mountain shape toward the other side. can do.

Now, it is assumed that the above-mentioned pneumatic tire is running on an ice-snow road or a wet road. At this time, since the tread block is deformed by receiving an external force from the road surface, the sipe groove formed in the block is crushed and tends to be closed, but as described above, the sipe groove is formed in a mountain shape toward one side. Since both the one-side protruding portion bent and protruding and the other-side protruding portion bent and protruded in a mountain shape toward the other side are provided, these one side,
The side walls of the sipe grooves in the other-side protruding portion abut against each other and abut against each other, thereby suppressing deformation of the block. As a result, the water on the snowy and wet roads and the wet roads is surely sucked into the sipe grooves, so that the collecting and draining properties are improved, and the running performance on the ice and snowy roads and the wet roads is improved. At this time, the one side and the other side protruding portions formed in the sipe groove protrude in a mountain shape toward the one side and the other side, respectively. However, even if the partitioning area is located on one side of the sipe groove and the partitioning area located on the other side are almost equal, as a result, the lateral stiffness of the block is almost uniform in any of the partitioning areas, and uneven wear is caused. The occurrence is effectively suppressed.

Further, according to the second aspect of the present invention, it is possible to effectively improve the collection and drainage of the sipe grooves while facilitating the removal of the sipe groove forming blade after vulcanization. Further, according to the structure of the third aspect, it is possible to suppress the deformation of the one-side and other-side protruding portions during running of the tire. Then, when vulcanizing the above-described pneumatic tire, if the vulcanizing mold as described in claim 4 is used, the above-mentioned sipe groove can be formed accurately and easily.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. 1 and 2, reference numeral 21 denotes a tread portion of a pneumatic tire 22 having excellent ice and snow performance. The tread portion 21 has two rubber layers, here an outer rubber layer 23 located radially outward and in contact with the road surface. And an inner rubber layer 24 located radially inward, and the outer rubber layer
Reference numeral 23 denotes a foamed rubber, that is, a rubber having a large number of closed cells inside, while the inner rubber layer 24 is formed of a normal rubber (non-foamed rubber) having a Shore A hardness higher than the Shore A hardness of the outer rubber layer 23. Have been. The volume ratio of the outer rubber layer 23 to the entire tread rubber needs to be 10% or more in order to improve ice and snow performance.

On the outer surface of the tread portion 21, a plurality of main grooves 26 extending in the circumferential direction and spaced apart in the axial direction, in this case, four main grooves A plurality of circumferentially separated sub-grooves 27 ending in the main groove 26 are formed. As a result, in the tread portion 21 between the two outermost main grooves 26, a plurality of rectangular blocks 28 are defined by the main grooves 26 and the sub-grooves 27,
A rib 29 extending continuously in the circumferential direction is provided in the tread portion 21 between the two outermost main grooves 26 and the tread end T.
Are formed respectively.

One or more (three) sipe grooves 33 are formed on the outer surface of any one of the blocks 28, here, all the blocks 28, and these sipe grooves 33 are formed by the sub-grooves 27. The main groove extends almost parallel to both ends
Open at 26. As a result, each block 28 is divided into a plurality of, in this case, four divided areas 34 separated in the circumferential direction by these sipe grooves 33.
Are substantially equal in any of the divided areas 34. The depths of the sipe grooves 33 are the same as those of the main groove 26 and the sub
The groove is slightly shallower than the groove depth of 27, and the deepest portion penetrates the outer rubber layer 23 to the inner rubber layer 24. The groove width W of the sipe groove 33 is considerably smaller than the groove widths of the main and sub-grooves 26 and 27, usually 0.5 mm to 1.5 mm, and is substantially the same throughout the sipe groove 33. When the groove width W of the sipe groove 33 is substantially the same over the entire area of the sipe groove 33, a part of the side wall of the sipe groove 33 partially bulges inward, so that the groove width is partially reduced. The collection and drainage properties are improved as compared to the case where the area becomes narrower.

2, 3, 4, and 5, each sipe groove 33
Has a plurality, here six one-side protrusions 35, and a plurality,
Here, six other-side protrusions 36 having the same number as the one-side protrusion 35 are provided.
The one-side protrusions 35 and the other-side protrusions 36 are alternately arranged in the longitudinal direction and the radial direction of the sipe groove 33. Here, the one side protruding portion 35 is bent and protruded in a mountain shape, here a frusto-conical shape, while the other side protruding portion 36 is a mountain shape toward the other side, here a frusto-conical shape. The remaining portion where the one side and the other side protruding portions 35 and 36 are not provided, that is, the main body portion 37 has a flat plate shape. The one side and the other side protruding portions 35 and 36 respectively protrude to the one side and the other side by substantially the same amount, and their protruding heights H and J are 0.5 to 3.0 times the groove width W of the sipe groove 33. Is preferably within the range. The reason is that if the protruding heights H and J are less than 0.5 times the groove width W, the blocks 28
This is because the deformation of the sipe groove 33 cannot be sufficiently suppressed, and as a result, the water collecting and draining properties of the sipe groove 33 cannot be effectively improved. This is because it becomes difficult to pull out the forming blade. In addition, these one side, the other side protrusions 35, 36 are number,
The shapes are the same, and the total protruding volume of the rubber protruding to one side is substantially equal to the total protruding volume of the rubber protruding to the other side. Regardless of the presence of the protrusions 35 and 36 on the side and the other side, they become substantially equal. Here, a cylindrical connecting rubber 38 for connecting the other side wall 35a and the one side wall 35b of the one side protruding portion 35 is provided at a central portion of the one side protruding portion 35, and these connecting rubbers 38 are provided.
Extends perpendicularly to the side wall of the sipe groove 33, and suppresses the crush deformation of the one-side protruding portion 35 during running of the tire 22, thereby preventing a decrease in water collecting and draining performance. On the other hand, the other side wall 36a and the one side wall 36b of the other side protrusion 36 are also provided at the center of the other side protrusion 36.
Is provided, and these connecting rubbers 39 extend orthogonally to the side walls of the sipe grooves 33,
When the tire 22 is running, the other-side protruding portion 36 is suppressed from being crushed and deformed, so that the collection / drainability is prevented from lowering.

The rib 29 is also provided with a plurality of sipe grooves 40 extending substantially parallel to the sub-groove 27. These sipe grooves 40 are semi-blind sipes whose inner ends are terminated in the middle of the rib 29. The other points are the same as those of the sipe groove 33.

Now, it is assumed that the aforementioned pneumatic tire 22 is traveling on an icy road or a wet road. At this time, the tread part
Since the block 28 of 21 is deformed by receiving a circumferential external force from the road surface, the sipe groove 33 formed in the block 28 is crushed and closes, but as described above, the sipe groove 33 faces one side. Since one side protruding portion 35 that bends and protrudes in a mountain shape and another side protruding portion 36 that protrudes in a mountain shape toward the other side are provided together, the other side protruding portions 35 and 36 The side walls 35a, 36a and the one side walls 35b, 36b abut against each other and abut against each other, so that the deformation of the block 28 is suppressed. As a result, the water on the icy road and the wet road is surely sucked into the sipe groove 33, and the water collecting and draining property is improved.
The running performance on wet roads is improved. At this time, the one side and the other side protrusions 35 and 36 protrude from the sipe groove 33 in the opposite direction in a mountain shape,
In addition, since the total protruding volumes of the protruding rubbers are substantially equal to each other, the rubber volume of the partition area 34 partitioned by the sipe grooves 33 is equal to that of any of the sipe grooves 33 even if these protruding portions 35 and 36 exist. The partition area 34 located on the side is substantially equal to the partition area 34 located on the other side. As a result, the lateral rigidity is substantially uniform in any of the partition areas 34, and the occurrence of uneven wear is effectively suppressed. Because The operation of the sipe groove 40 is the same as described above.

2, 6, and 7, reference numeral 41 denotes a vulcanizing mold used for vulcanizing the pneumatic tire 22 described above.
The vulcanizing mold 41 has a tread molding surface 42 for molding the tread portion 21. The tread surface 42 has a plurality of main bones 43 extending substantially in the circumferential direction and spaced apart in the axial direction, here, four protruding main bones 43, and a plurality of main bones 43 intersecting at right angles to the main bones 43 and separated in the circumferential direction. The main bone 43 is provided with the accessory bone 44.
The main groove 26 is formed in the tread portion 21 of the unvulcanized tire, and the sub bone 44 forms the sub groove 27. Here, the accessory bone 44 terminates at the outermost main bone 43, and as a result, the tread mold surface 42
Are formed with a plurality of recesses 46 surrounded by two outermost main bones 43 and accessory bones 44, and these recesses 46 form blocks 28 in the tread portion 21 of the unvulcanized tire. The rib 29 is formed by an annular recess between the two outermost main bones 43 and both ends of the tread forming surface 42.

Reference numeral 50 denotes blades for forming sipe grooves 33 on the outer surface of the block 28. These blades 50 are provided in at least some of the recesses 46, here at least one in all the recesses 46, Three are provided. Each blade 50 has a buried portion 51 at the outer end in the radial direction, and the buried portion 51 is buried in the vulcanizing mold 41. Reference numeral 52 denotes a sipe forming portion extending radially inward from the buried portion 51. The sipe forming portion 52 protrudes from the surface (bottom surface) of the recess 46. In addition, the sipe forming portion 52 extends substantially parallel to the accessory bone 44 and both ends contact the main bone 43, and the height thereof is the same at any position, and is slightly higher than the height of the main bone 43 and the accessory bone 44. Low. As a result, each recess 46 has these blades 50
Are divided into a plurality of, in this case, four, divided areas 53 separated in the circumferential direction by the sipe forming section 52.
Are substantially equal in any of the divided areas 53. The thickness N of the blade 50 is considerably smaller than the thickness of the main and sub bones 43 and 44, usually 0.5 mm to 1.5 mm, and is substantially the same throughout the entire area.

In each blade 50, a sipe forming portion 52 is partially bent by embossing at a plurality of portions, in this case, one side bent portion 55 formed by bending at six positions, and the same number of positions (six positions) as the one side bent portion 55. The other-side bent portion 56 is formed by bending the blade 50. The one-side bent portion 55 and the other-side bent portion 56 are alternately arranged in the longitudinal direction and the radial direction of the blade 50. Here, the one-side bent portion 55 has a mountain shape toward one side,
Here, it protrudes in a truncated cone shape, while the other side bend 56 projects in a mountain shape toward the other side, here a frustoconical shape, but these one side, the other side bends 55 and 56 are provided. The remaining portion, that is, the main body portion 57 has a flat plate shape. The one-side and other-side bent portions 55 and 56 project by substantially the same amount to the one side and the other side, respectively, and form one-side and other-side protrusions 35 and 36 in each sipe groove 33. In addition, these one side and the other side bent portions 55 and 56 are the same in number and shape, and from this, the total protruding volume to one side and the total protruding volume to the other side are almost equal, and as a result, The volume of the divided area 53 is substantially equal regardless of the existence of the bent portions 55 and 56 on one side and the other side.
Here, through-holes 58, 59 having a circular cross section are formed in the central portions of the one-side and other-side bent portions 55, 56, respectively, and these through-holes 58, 59 extend orthogonally to the main body 57. , Each sipe groove
33 are formed with cylindrical connecting rubbers 38 and 39. A blade (not shown) for forming a sipe groove 40 is provided in the annular recess between the two outermost main bones 43 and both ends of the tread forming surface 42.

When vulcanizing an unvulcanized tire using such a vulcanizing mold 41, the unvulcanized tire is stored in the vulcanizing mold 41 and then placed in a bladder at a high temperature. The unvulcanized tire is pressed against a molding surface, including the tread molding surface 42, by injecting a high pressure vulcanizing medium. At this time, main bone 43, accessory bone 4
4. The sipe forming portion 52 of the blade 50 is pushed into the tread portion 21 of the unvulcanized tire, and a plurality of main grooves 26 and sub-grooves 27 are formed on the outer surface of the tread portion 21. A sipe groove 33 as described above is accurately and easily formed on the outer surface of the block 28 defined by 27. Thereafter, the vulcanizing mold 41 is opened, and at this time, the blade 50
The connection rubbers 38 and 39 remain in the sipe groove 33 because the connection rubbers 38 and 39 are pulled out from the tread portion 21 while cutting the middle of the connection 38 and 39.

FIGS. 8 and 9 show a second embodiment of the present invention. In this embodiment, a rectangular tongue piece is cut and raised at a plurality of positions from the blade 60 and bent, and one side bent portion 61 protruding in a triangular mountain shape toward one side and projecting in a triangular mountain shape toward the other side. The other-side bent portion 62 is formed. As a result, when a sipe groove is formed in the tread portion 21 using these blades 60, the sipe groove is formed with the one side and the other side protrusion that are complementary to the one side, the other side bent parts 61 and 62. You. Since a slit-shaped gap is formed between the protruding ends of these one-side and other-side bent portions 61 and 62 and the flat main body 63 of the blade 60, one side wall of the sipe groove and the other side are formed. The side wall is connected by a slit-shaped connection rubber. Other configurations and operations are the same as those of the first embodiment.

FIGS. 10 and 11 show a third embodiment of the present invention. In this embodiment, the blade 65 is formed with a plurality of one-side bent portions 66 protruding toward one side and a plurality of other-side bent portions 67 protruding toward the other side. The portions 66 and 67 are formed in an oval cross section, and are arranged in a staggered manner. As a result, when a sipe groove is formed in the tread portion 21 using these blades 65,
In the sipe groove, one-side and other-side protruding portions which are complementary to the one-side and other-side bent portions 66 and 67 are formed. Other configurations and operations are the same as those of the first embodiment.

FIGS. 12 and 13 show a fourth embodiment of the present invention. In this embodiment, a plurality of one-side bent portions 71 having a circular cross section protruding toward one side and other-side bent portions 72 having a rectangular cross section protruding toward the other side are formed on the blade 70, respectively. The side and other side bent portions 71 and 72 are alternately arranged in the longitudinal direction of the blade 70. As a result, when a sipe groove is formed in the tread portion 21 using these blades 70, the sipe groove is formed with the one side, the other side projection that is complementary to the one side, the other side bent parts 71 and 72, and the other side. You. Other configurations and operations are the same as those of the first embodiment.

FIGS. 14 and 15 show a fifth embodiment of the present invention. In this embodiment, the blade 75 has one one-side bent portion 76 having a heart-shaped cross section protruding toward one side and a plurality of other-side bent portions 77 having a rectangular cross section protruding toward the other side. Are formed, and the one-side bent portion is formed.
76 is arranged at the center of the blade 75 in the longitudinal direction, and the other-side bent portion 77 is arranged at both ends of the blade 70 in the longitudinal direction. As a result, when a sipe groove is formed in the tread portion 21 using these blades 75, the sipe groove is formed with the one side and the other side protrusion that are complementary to the one side and the other side bent portions 76 and 77. You. Other configurations and operations are the same as those of the first embodiment.

In the above-described embodiment, the tread portion 21 is composed of the two rubber layers of the outer rubber layer 23 made of foamed rubber and the inner rubber layer 24 made of normal rubber (non-foamed rubber). In the present invention, the entire tread portion 21 may be made of ordinary rubber. Further, in the present invention, the one side and the other side protruding portions may have an X-shaped, diamond-shaped, hexagonal or the like cross-sectional shape.

[0024]

As described above, according to the present invention, it is possible to improve running performance on icy and snowy roads and wet roads while suppressing uneven wear.

[Brief description of the drawings]

FIG. 1 is a plan view of a tread portion showing a first embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view showing a block.

FIG. 3 is a sectional view taken along the line II of FIG. 2;

FIG. 4 is a sectional view taken along the line II-II in FIG. 2;

FIG. 5 is a sectional view taken along the line III-III in FIG. 2;

FIG. 6 is a partially cutaway perspective view showing a vulcanizing mold.

FIG. 7 is a sectional view taken along the line IV-IV in FIG. 6;

FIG. 8 is a partially broken perspective view of a blade showing a second embodiment of the present invention.

FIG. 9 is a sectional view taken along the line VV of FIG. 8;

FIG. 10 is a front view showing the vicinity of a blade according to a third embodiment of the present invention.

FIG. 11 is a sectional view taken along the line VI-VI in FIG. 10;

FIG. 12 is a front view showing the vicinity of a blade according to a fourth embodiment of the present invention.

13 is a sectional view taken along the line VII-VII in FIG.

FIG. 14 is a front view showing the vicinity of a blade according to a fifth embodiment of the present invention.

15 is a sectional view taken along the line VIII-VIII in FIG.

FIG. 16 is a sectional view of a block showing a conventional sipe groove.

[Explanation of symbols]

 21 ... Tread 22 ... Pneumatic tire 26 ... Main groove 27 ... Sub groove 28 ... Block 33 ... Sipe groove 35 ... One side protruding part 36 ... Other side protruding part 38,39 ... Connecting rubber 41 ... Vulcanizing mold 42 … Tread surface 43… main bone 44… accessory bone 46… recess 50… blade 55… one side bend 56… other side bend

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B29K 105: 24 B29L 30:00

Claims (4)

[Claims] A plurality of blocks defined by a plurality of circumferentially extending main grooves provided on a tread portion and a plurality of sub-grooves intersecting the main grooves are provided. In a pneumatic tire in which a sipe groove extending substantially parallel to the sub-groove is formed, the groove width W of the sipe groove is made substantially the same over the entire area of the sipe groove, and the sipe groove is formed in a mountain shape toward one side. A pneumatic tire having both a one-side protruding portion bent and protruding and a second-side protruding portion bent in a mountain shape toward the other side. 2. The pneumatic tire according to claim 1, wherein the heights H and J of the one side and the other side protrusions are both within a range of 0.5 to 3.0 times the width W of the sipe groove. 3. The pneumatic tire according to claim 1, wherein a connecting rubber for connecting one side wall and the other side wall of the sipe groove is provided at a position where the one side and the other side projecting portions are arranged. 4. A plurality of main bones forming a main groove extending in a circumferential direction and a plurality of sub-bones forming a sub-groove intersecting the main groove are provided on a tread portion of the pneumatic tire.
A pneumatic tire having a tread-molded surface provided with a blade that forms a sipe groove extending substantially parallel to a sub-groove in any of the recesses surrounded by the main and sub-bones and forming a plurality of blocks in the tread portion. In the vulcanizing mold of
The blade has substantially the same thickness throughout the entire area, and the blade is partially bent at a plurality of locations and protrudes in a mountain shape toward one side and protrudes in a mountain shape toward the other side. A vulcanizing mold for a pneumatic tire, comprising a bent portion on the other side.