JPH0994828A - Vulcanization molding mold and pneumatic tire produced using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of the curve or a blade during vulcanization molding and to keep the ice performance of a product tire in a good condition. SOLUTION: A pair of blades 28 in which a part corresponding to zigzag shape and a sipe bottom is made to be a flask shape is installed in the recessed part 26 of a vulcanization molding mold 24. Since the rigidity of the blades 28 can be increased in comparison with a blade for forming a straight line sipe, the generation of the curve of a blade can be prevented. A studless pneumatic tire formed by the mold 24 is to be equipped with a lateral sipe in which a cross section form of a zigzag shape and a sipe bottom is made a flask shape so that the ice performance of the tire can be kept in a good condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vulcanization molding mold used when a pneumatic tire having a block pattern is manufactured by vulcanization molding, and a pneumatic tire manufactured using the vulcanization molding mold.

[0002]

2. Description of the Related Art With the prohibition of use of spiked tires, various improvements in treads have been made in search of better studless tires.

In this type of studless tire, in order to increase the edge component and improve the performance on ice,
A tread portion may be configured by a block pattern divided by a plurality of main grooves extending in the circumferential direction and a plurality of lug grooves extending in a direction intersecting with the main grooves, and a large number of lateral sipes may be arranged on the block land portion. It is useful.

The above-mentioned lateral sipes are classified into two types, that is, open sipes on both sides that cross the land portion, and open sipes on one side that open at one end to the main groove and substantially end at the other end inside the land portion. Be separated. The former has the advantage of increasing the edge component more than the latter, but due to the decrease in block rigidity, uneven wear resistance and DRY steering stability (steering stability on dry road surfaces) are reduced compared to the latter. There is a disadvantage. On the contrary, the latter has the disadvantage that the edge component is reduced as compared with the former, but has the advantage that the uneven wear resistance and the DRY steering stability are better than the former because the block rigidity does not decrease. Although there is a disadvantage in both the double-sided open sipe and the single-sided open sipe, this disadvantage does not cause any trouble.

[0005]

However, in order to manufacture a tire equipped with any of the above-described lateral sipes, a blade for forming sipes is formed in the recess for forming blocks of the vulcanization mold. However, since the blade for forming the sipe is an extremely thin plate material, its rigidity tends to be insufficient. Therefore, blade bending may occur during vulcanization molding.

[0006] By application, particularly in the case of heavy-duty tires used for trucks, buses, etc., since the sipe depth is deep and the tread rubber is hard, a large force is applied to the tread during vulcanization molding to bend the blade. Is likely to occur.

By type, in the case of a one-sided open sipe,
Only two of the four sides (bottom side and one side) are fixed in the recess (that is, in the case of a one-sided open sipe, the blade has a one-sided support structure), which reduces the blade support rigidity. As a result, blade bending tends to occur during vulcanization molding.

[0008] Further, there is also a demand for improving the drainage performance of the pneumatic tire having the lateral sipe of this type so as to maintain the good performance on ice.

In view of the above facts, the present invention is capable of preventing the occurrence of blade bending during vulcanization molding, and moreover, is capable of maintaining good on-ice performance of a commercialized tire, The purpose is to obtain a pneumatic tire manufactured using this.

[0010]

The present invention according to claim 1 is divided into a plurality of blocks by a main groove formed along the tire circumferential direction and a lug groove formed along the tire width direction. A vulcanization molding mold used in manufacturing a pneumatic tire having a block pattern by vulcanization molding, having a blade for forming a lateral sipe formed in the block and extending along the tire width direction. The blade is provided with at least one bent portion and the portion corresponding to the sipe bottom of the blade has a flask-shaped cross section.

The present invention according to claim 2 is characterized in that a portion corresponding to the sipe bottom of the blade having a flask-shaped cross section is divided based on the bent portion of the blade.

The present invention according to claim 3 is characterized in that it is manufactured by using the vulcanization molding mold according to claim 1 or 2.

According to a fourth aspect of the present invention, the lateral sipe in the pneumatic tire according to the third aspect is a one-sided open sipe whose one end is opened to the block end and the other end is substantially terminated in the block land portion. It is characterized by

The present invention according to claim 5 is characterized in that the cross-sectional shape of the other end of the lateral sipe is also a flask shape.

According to the first aspect of the present invention, the blade for forming the lateral sipe extending in the tire width direction is provided with at least one bent portion.
The rigidity of the blade is higher than that of a blade for forming a straight sipe. Therefore, no bending of the blade occurs during vulcanization molding.

Further, according to the present invention, since the cross-sectional shape of the portion corresponding to the sipe bottom of the blade is a flask shape, the cross-sectional shape of the sipe bottom of the lateral sipe formed by this blade is also a flask shape. Due to this, good performance on ice is maintained. That is, as described above,
When the blade is provided with at least one bent portion and the lateral sipe is formed into a bent shape, the edge portion of the lateral sipe comes into contact with the drainage performance. For this reason,
The friction coefficient μ on the snowy and snowy road surface may decrease, and the performance on ice may decrease. However, in the present invention, since the cross-sectional shape of the portion corresponding to the sipe bottom of the blade is made into the flask shape, the cross-sectional shape of the sipe bottom of the lateral sipe is made into the flask shape, so that the drainability from the sipe bottom is improved. For this reason, the friction coefficient μ on the snowy and snowy road surface can be increased, and the performance on ice can be favorably maintained.

That is, according to the vulcanization molding mold according to the present invention described in claim 1 or 2, and the pneumatic tire according to the present invention described in claim 3 manufactured using the vulcanization molding mold, the vulcanization molding is performed. It is possible to prevent the occurrence of blade bending and maintain the performance on ice at the same time.

By making the cross-sectional shape of the sipe bottom a flask shape, the stress at the sipe bottom is dispersed. Therefore, the occurrence of cracks at the bottom of the sipe is prevented.

According to a second aspect of the present invention, in the first aspect of the invention, the portion corresponding to the sipe bottom of the blade having a flask-shaped cross section is defined with reference to the bent portion of the blade. Since it is divided, there is an advantage that it is easier to manufacture than when it is not divided.

According to the fourth aspect of the present invention, the pneumatic tire according to the third aspect is a one-sided open sipe in which one end of the lateral sipe is opened to the block end and the other end is substantially terminated in the block land portion. Since I configured the horizontal sipe in
Compared with the case of opening sipes on both sides (open sipes),
Block rigidity can be improved, and uneven wear resistance and DRY steering stability are improved.

According to the present invention of claim 5, claim 4
In the invention described in (1), since the cross-sectional shape of the other end of the horizontal sipe is also the flask shape, the occurrence of cracks at the other end of the horizontal sipe is prevented. Therefore, it becomes possible to further suppress the occurrence of cracks in combination with the effect of preventing the occurrence of cracks at the bottom of the sipe. By making the cross-sectional shape of the other end of the horizontal sipe into a flask shape, drainage at the other end of the horizontal sipe is also improved.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 1, the studless pneumatic tire 10 has a cylindrical tread 12 that extends over a pair of left and right sidewalls (not shown). In the tread 12, a plurality of main grooves 14 formed along the tire circumferential direction and a plurality of lug grooves 16 formed along the tire width direction are formed, whereby a plurality of blocks 18 are formed. It is compartmentalized. These blocks 18
A lateral sipe 20 that extends along the tire width direction is formed on the.

FIG. 2 shows a plan view of a single block. As shown in this figure, a pair of lateral sipes 20 is formed on the block 18. Which side sipe 2
0 also has one end opened to the main groove 14 and the other end terminated in the block land portion 18A. That is, the lateral sipe 20 of this embodiment is a one-sided open sipe. Further, the lateral sipe 20 has sipe bending portions 22 at four locations along the width direction of the block 18 (the extending direction of the lateral sipe 20). As a result, the lateral sipe 20 is formed in a zigzag shape when viewed in the direction perpendicular to the plane of the block 18.

FIG. 3 shows the cross-sectional shape of the lateral sipe 20. As shown in this figure, the lateral sipe 20 is
It is composed of a sipe base portion 20A having an elongated rectangular cross-sectional shape and a sipe bottom portion 20B formed continuously with the sipe base portion 20A and having a flask cross-sectional shape.

Next, the structure of the vulcanization molding mold 24 used when manufacturing the studless pneumatic tire 10 having the lateral sipe 20 described above will be described.

FIG. 4 is a perspective view showing a recess 26 for forming the block 18 in the vulcanization mold 24. As shown in this figure, the concave portion 26 for forming the block 18 is a substantially rectangular parallelepiped concave portion, and a pair of thin plate-shaped blades 28 for forming the lateral sipe 20 are provided inside thereof. It is arranged. The one blade 28 includes one side wall 26 </ b> A of the recess 26 and the bottom wall 2.
It is fixed to 6B. The other blade 28 is
It is fixed to the other side wall 26C and bottom wall 26B of the recess 26. A vent hole (not shown) for opening to the atmosphere is formed on the bottom wall 26B of the recess 26.

FIG. 5 shows a perspective view of a single blade. As shown in this figure, the blade 28 includes a flat plate-shaped blade base 28A and the blade base 28A.
28B provided at one end in the height direction of the
And is constituted by. The blade base portion 28A and the flask portion 28B have blade bending portions 30 at four locations along the width direction of the recess 26. As a result, the blade 28 is formed in a zigzag shape when viewed from the height direction of the recess 26. Therefore, this blade 28
Has a higher rigidity than a straight blade. Further, since the blade 28 has a zigzag shape, the blade 28 is supported on one side by the recess 26, but the supporting area is larger than that of a linear blade. Therefore, the blade 28
The supporting rigidity of the concave portion 26 is high.

The dimensions of the block 18 are as follows: block length 23 mm, block width 30 mm, sipe width 0.5 m.
It is set to m and a sipe depth of 10 mm. The diameter of the sipe bottom portion 20B is set to 2 mm. further,
The depth of the main groove 14 is set to 20 mm, and the depth of the lug groove 16 is set to 15 mm. The tire size is 11R22.
5

Next, the operation and effect of this embodiment will be described. When an unvulcanized green tire is filled in the vulcanization molding mold 24 and pressure is applied to the unvulcanized green tire by a bladder (not shown) arranged inside the green tire,
The rubber of the green tire flows into the recess 26. This allows
The air in the recess 26 is released to the atmosphere through a vent hole (not shown), and the rubber of the green tire reaches every corner of the recess 26 and is brought into close contact with the inner surface of the mold. Then, the vulcanization mold 24
The green tire therein is vulcanized at a predetermined temperature for a predetermined time. As a result, the studless pneumatic tire 10 including the lateral sipe 20 having a zigzag shape and a sipe bottom having a flask-shaped cross-section is molded.

Here, in the present embodiment, the blade 28 is provided with a plurality of blade bending portions 30 to form a zigzag shape to enhance the rigidity of the blade 28 itself and also the rigidity of supporting the blade 28 in the recess 26. Therefore, even if pressed by the rubber of the raw tire during vulcanization molding, the blade 2
It is possible to prevent deformation such as bending of the member 8.

Further, the blade 28 has a flask portion 28B.
Since the sipe bottom portion 20B having the cross-sectional shape of the flask is formed on the lateral sipe 20 of the block 18 after the molding, the studless pneumatic tire 10 can maintain good on-ice performance. That is, lateral sipe 2
When a plurality of sipe bending portions 22 are formed at 0, the edge portions of the lateral sipe 20 come into contact with each other, and the drainage performance deteriorates. For this reason, the friction coefficient μ on the snowy and snowy road surface is lowered, and the performance on ice may be lowered. However, in this embodiment, since the cross-sectional shape of the sipe bottom portion 20B of the lateral sipe 20 is a flask shape, the drainability from the sipe bottom portion 20B can be improved. For this reason, the friction coefficient μ on the ice and snow road surface can be increased, and the performance on ice can be favorably maintained.

That is, according to the present embodiment, the occurrence of bending of the blade 28 during vulcanization molding is prevented, and the studless pneumatic tire 10 manufactured by the vulcanization molding mold 24 equipped with this blade 28 has good icing properties. Performance can be maintained at the same time.

According to this embodiment, the lateral sipe 20
By making the cross-sectional shape of the sipe bottom 20B into a flask shape, the stress acting on the sipe bottom 20B can be dispersed. Therefore, according to the present embodiment, it is possible to prevent cracks from occurring in the sipe bottom portion 20B.

Further, according to this embodiment, the lateral sipe 20
Since one end of the side sipe is open to the main groove 14 of the block 18 and the other end is substantially terminating inside the block land portion 18A, the lateral sipe 20 is configured, so that when the both side opening sipe (open sipe) is used. In comparison, the rigidity of the block 18 can be improved, and the uneven wear resistance and the DRY steering stability can be improved.

In order to verify the above-mentioned effects, a test was carried out on the studless pneumatic tire 10 of the present embodiment for braking performance on ice and whether or not blade bending occurred during vulcanization molding. The test results are shown in Table 1 below.
It is as follows.

In the test, the studless pneumatic tire 10 according to the present embodiment, the vulcanization molding mold 24 for manufacturing the studless pneumatic tire 10 and the comparative tire 1 (as shown in FIG. 6, the sipe bottom is linear and the sipe bottom has a flask cross section). A studless pneumatic tire including a block 34 having an unshaped lateral sipe 32), a vulcanization mold (not shown) for manufacturing the same, a comparative tire 2 (as shown in FIG. 7, zigzag and A studless pneumatic tire having a block 38 with a lateral sipe 36 in which the bottom of the sipe is not a flask cross-sectional shape) and a vulcanization molding mold (not shown) for manufacturing the same were performed.

Further, the test result of the braking performance on ice is
The tires are mounted on a vehicle, sudden braking is applied while the vehicle is running at a speed of 20 km / h, the distance from the point where the braking is applied to the point where the braking is stopped is measured, and the reciprocal thereof is expressed as an index on ice.

[0039]

[Table 1] As can be seen from Table 1 above, the comparative tire 1 provided with the lateral sipe 32 having a linear sipe whose cross-sectional shape of the sipe bottom is not a flask shape and does not have a sipe bending portion has good braking performance on ice, but a blade. There is a bend. In addition, a horizontal sipe 36 which has a sipe bent portion but whose cross-sectional shape of the sipe bottom is not a flask shape.
In the comparative tire 2 equipped with, no blade bending occurred, but the braking performance on ice was deteriorated. On the other hand, in the present embodiment, which is provided with a lateral sipe having a zigzag shape having a sipe bent portion and the cross-sectional shape of the sipe bottom is a flask shape, the braking performance on ice is good, and the blade does not bend. I understand.

Another embodiment will be briefly described below with reference to FIGS. 8 to 10. In the embodiment shown in FIG. 8, as shown in FIG. 8B, a pair of hook-shaped deformed sipes 42 are alternately formed on the block 40. Each hook-shaped deformed sipe 42 has a sipe bending portion 44 at one place, and also has a sipe bottom portion 42A and the other end 42 of the sipe.
The two cross-sectional shapes of B are flask-shaped.

FIG. 8A shows a perspective view of a blade 46 for forming the hook-shaped deformed sipe 42 described above. As shown in this figure, the blade 46 is formed in a hook shape having a blade bent portion 48 at one place. Further, cylindrical flask portions 46B are provided at two locations, the lower end edge of the blade base portion 46A and the side edge on the bent side.

According to the above-described embodiment, similarly to the above-described embodiments, it is possible to prevent the occurrence of blade bending at the time of vulcanization molding and to obtain a good studless pneumatic tire manufactured by the vulcanization molding mold including the blade 46. The performance on ice can be maintained at the same time.

Further, since the hook-shaped deformed sipe 42 is also a one-sided open sipe, the rigidity of the block 40 can be improved and the uneven wear resistance and the DRY steering stability can be improved as compared with the case of the both-sided open sipe. be able to.

Further, according to the present embodiment, by providing the cylindrical flask portion 46B not only on the lower end edge of the blade base 46A but also on the side edge on the bent side, the other end of the sipe of the hook-like deformed sipe 42 is provided. Since the cross-sectional shape of 42B is also a flask shape, it is possible to prevent the occurrence of cracks at the other end 42B of the hook-shaped deformed sipe 42. For this reason, it is possible to further suppress the occurrence of cracks in combination with the effect of preventing the occurrence of cracks at the sipe bottom portion 42A. Therefore, it is effective when the input is severe (when softer cap rubber is used and the amount of deformation of the block increases or when the sipe width and the sipe depth are large). By setting the cross-sectional shape of the sipe other end 42B of the hook-shaped deformed sipe 42 to the flask shape, the drainage property at the sipe other end 42B of the hook-shaped deformed sipe 42 can be improved.

In the embodiment shown in FIG. 9, FIG.
As shown in FIG. 5, a pair of hook-shaped deformed sipes 52 are alternately formed on the block 50. Each hook-shaped deformed sipe 52 has sipe bent portions 54 at three positions, and the sipe bottom portion 52A has a flask-shaped cross section.

FIG. 9A is a perspective view showing the blade 56 for forming the hook-shaped deformed sipe 52 described above. As shown in this drawing, the blade 56 is formed in a hook shape having blade bent portions 58 at three positions. A cylindrical flask portion 56B is provided at the lower end edge of the blade base portion 56A.

According to the above-described embodiment, similarly to the above-described embodiments, it is possible to prevent the occurrence of blade bending at the time of vulcanization molding and to obtain a good studless pneumatic tire manufactured by the vulcanization molding mold including the blade 56. The performance on ice can be maintained at the same time.

Further, since the hook-shaped deformed sipe 52 is also a one-sided open sipe, compared to the case of the both-sided open sipe,
The rigidity of the block 50 can be improved, and the uneven wear resistance and the DRY steering stability can be improved.

In the embodiment shown in FIG. 10, a pair of tuning fork-shaped deformed sipes 62 are alternately formed on the block 60 as shown in FIG. Each tuning fork-shaped deformed sipe 62 has sipe bent portions 64 at three positions, and the sipe bottom portion 62A has a flask-shaped cross section.

FIG. 10A is a perspective view showing a blade 66 for forming the tuning fork-shaped deformed sipe 62 described above. As shown in this figure, the blade 66 is formed in a tuning fork shape having blade bent portions 68 at three positions. Further, at the lower edge of the blade base 66A,
A cylindrical flask portion 66B is provided.

According to the above-described embodiment, similarly to the above-described embodiments, it is possible to prevent the occurrence of blade bending during vulcanization molding and to obtain a good studless pneumatic tire manufactured by the vulcanization molding mold including the blade 66. The performance on ice can be maintained at the same time.

Further, since this tuning fork-shaped deforming sipe 62 is also a one-sided opening sipe, the rigidity of the block 60 can be improved and the uneven wear resistance and the DRY steering stability can be improved as compared with the case of the both-sided opening sipe. be able to.

In the above embodiment, the one-sided open sipe has been described as an example, but the present invention is not limited to this, and both-sided open sipe may be adopted. In this case, the blade is supported by the concave portion on three sides except the top side.

The blade bent portion and the sipe bent portion may be provided at at least one place.

Further, in the above-mentioned embodiment, the structure in which the flask portion provided on the blade is bent and integrated with the bent shape of the blade has been described. It is also possible to adopt a configuration in which the division is performed. For example, the hook-shaped blade 70 shown in FIG. 11 has blade bent portions 72 at three positions, and further has a blade base portion 7.
A cylindrical flask portion 70B divided into a plurality of pieces is provided at the lower end portion of 0A. This flask portion 70B is
The blade bending portion 72 is divided as a reference, and each of them is formed in a linear shape. According to this configuration,
Compared to the case where the flask portion that is bent along the bent shape of the blade 70 and is integrally formed is provided, the manufacturing becomes easier. The end of each flask portion 70B in the longitudinal direction is spherical and has a configuration capable of substantially ensuring a point contact state. However, the present invention is not limited to this, and it depends on the bending angle of the blade 70. The end portion may be cut so as to form an inclined surface to enhance the continuity of the flask portion. Further, a configuration may be adopted in which the flask portion 70B having a spherical end portion is used and then the gap between the adjacent end portions is filled by welding or the like.

[0056]

As described above, the vulcanization molding mold according to the present invention and the pneumatic tire manufactured using the vulcanization molding mold can prevent the occurrence of blade bending during vulcanization molding, and can be commercialized. It has an excellent effect that the on-ice performance of the prepared tire can be favorably maintained.

[Brief description of drawings]

FIG. 1 is a tread plan view of a studless pneumatic tire according to the present embodiment.

FIG. 2 is a plan view of the block shown in FIG.

FIG. 3 is a cross-sectional view showing the lateral sipe shown in FIG. 2 taken along the tire circumferential direction.

FIG. 4 is a perspective view of a recess for forming a block in a vulcanization mold.

5 is a perspective view of the single blade shown in FIG. 4. FIG.

FIG. 6 is a plan view of a block corresponding to FIG. 2 of a comparative tire 1 for explaining the effect of this embodiment.

FIG. 7 is a plan view of a block corresponding to FIG. 2 of a comparative tire 2 for explaining the effect of this embodiment.

FIG. 8 relates to another embodiment (hook-shaped deformed sipes),
(A) is a perspective view of a blade and (B) is a plan view of a block.

FIG. 9 relates to another embodiment (hook-shaped deformed sipes),
(A) is a perspective view of a blade and (B) is a plan view of a block.

FIG. 10 relates to another embodiment (tuning fork-shaped deformation sipe),
(A) is a perspective view of a blade and (B) is a plan view of a block.

FIG. 11 is a perspective view showing another embodiment of the blade.

[Explanation of symbols]

 10 Studless Pneumatic Tire 14 Main Groove 16 Lug Groove 18 Block 18A Block Land 20 Transverse Sipe 20B Sipe Bottom 22 Sipe Bend 24 Vulcanization Mold 28 Blade 28B Flask 30 Blade Bend 40 Block 42 Hook Shape Sipe (Horizontal) Sipe) 44 sipe bent part 46 blade 48 blade bent part 50 block 52 hook-shaped deformed sipe (horizontal sipe) 54 sipe bent part 56 blade 58 blade bent part 60 block 62 tuning-fork deformed sipe (side sipe) 64 sipe part bent 68 Blade Bend 70 Blade 72 Blade 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 (5)

[Claims] 1. A pneumatic tire having a block pattern divided into a plurality of blocks by a main groove formed along the tire circumferential direction and a lug groove formed along the tire width direction is manufactured by vulcanization molding. A vulcanization molding mold used in the case of having a blade for forming a lateral sipe formed in the block and extending along the tire width direction, the blade is provided with at least one or more bent portions In addition, the vulcanization molding mold is characterized in that the cross-sectional shape of the portion corresponding to the sipe bottom of the blade has a flask shape. 2. The vulcanization molding mold according to claim 1, wherein a portion corresponding to the sipe bottom of the blade having a flask-shaped cross section is divided based on a bent portion of the blade. 3. A pneumatic tire manufactured by using the vulcanization molding mold according to claim 1 or 2. 4. The lateral sipe of the pneumatic tire according to claim 3, wherein the lateral sipe is a one-sided sipe that has one end opening to the block end and the other end substantially terminating inside the block land portion. Pneumatic tires. 5. The pneumatic tire according to claim 4, wherein the cross-sectional shape of the other end of the lateral sipe is also a flask shape.