JPH0994829A - Vulcanization molding mold and pneumatic tire produced using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of the curve of 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 arranged in the recessed part 26 of a vulcanization molding mold 24. In this way, the generation of the curve of the blades can be prevented during vulcanization molding, and the ice performance of a product tire can be kept in a good condition. Furthermore, since a flask part 28B is formed in a straight line form, the generation of strain is prevented even when lateral force is applied so that the crack resistance of the product tire can be improved.

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 of the blade corresponding to the sipe bottom is linear and its cross-sectional shape is flask-shaped.

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

According to a third aspect of the present invention, the lateral sipe in the pneumatic tire according to the second 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 4 is characterized in that the cross-sectional shape of the other end of the lateral sipe is also a flask shape.

According to the present invention, the blade for forming the lateral sipe extending along 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 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 formed by this blade also becomes the flask shape. And the performance on ice is kept good. That is, as described above, when at least one bent portion is provided on the blade and the lateral sipe has 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 is lowered, and the performance on ice may be lowered. However, in the present invention, the cross-sectional shape corresponding to the sipe bottom of the blade is made into a flask shape so that the cross-sectional shape of the sipe bottom of the lateral sipe is made into a flask shape, so that drainage 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 and the pneumatic tire according to the present invention described in claim 2 manufactured by using the molding mold, the blade bending during vulcanization molding is prevented. It is possible to achieve both prevention of generation and maintenance of performance on ice.

Further, according to the present invention, although the blade is provided with at least one bent portion,
Since the portion corresponding to the sipe bottom of the blade is linear, the crack resistance of the pneumatic tire according to the present invention according to claim 2 produced by using the vulcanization mold according to the present invention according to claim 1 has Be improved. In other words, at least one or more bends are also provided in the portion corresponding to the sipe bottom of the blade, and if the sipe bottom of the lateral sipe of the pneumatic tire that is the product is also provided with the bend, the road surface becomes a block. When a lateral force is input, the strain may be concentrated in the bent portion and cracks may be scattered. However, in the present invention, since the portion of the blade corresponding to the sipe bottom is linear, strain does not concentrate when a lateral force is input. Therefore, the crack resistance of the pneumatic tire is improved. Since the cross-sectional shape of the sipe bottom has a flask shape, the stress at the sipe bottom is dispersed, so that the sipe bottom also has a flask shape to suppress cracking.

According to the third aspect of the present invention, the pneumatic tire according to the second 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 4, claim 3
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.

[0020]

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 is provided with a cylindrical tread 12 that straddles 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 three 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. Of these, the sipe base portion 20A extends in a zigzag shape as seen from the direction perpendicular to the area of the block 18 as described above, but the sipe bottom portion 20B extends in a straight line.

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. Of these, the flask part 2
8B is linearly formed. On the other hand, the blade base portion 28A has the blade bent portions 30 at three positions 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, the blade 28 has higher rigidity than the straight blade. Further, since the blade 28 has a zigzag shape, the recess 26
Although it is supported on one side, the support area is increased compared to a straight blade. Therefore, the supporting rigidity of the blade 28 in the recess 26 is also 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, a plurality of blade bent portions 30 are provided on the blade base portion 28A of the blade 28.
Since it is formed in a zigzag shape by increasing the rigidity of the blade 28 itself and the supporting rigidity of the concave portion 26 of the blade 28 is also increased, even if pressed by the rubber of the raw tire during vulcanization molding, It is possible to prevent deformation such as bending.

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. Note that the road surface temperature (ice temperature) is high (0 ° C).
(Near C), the drainage property decreases when a water film exists on the surface of ice. 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, drainage from the sipe bottom portion 20B can be improved even when the road surface temperature is near 0 ° C. 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.

Further, in this embodiment, the blade base 2
8A was formed in a zigzag shape, but the flask portion 28
By forming B in a straight shape, the sipe bottom 20B of the lateral sipe 20 of the block 18 after molding is made in a straight shape, so that the crack resistance of the studless pneumatic tire 10 can be improved. That is, if the flask part of the blade is also zigzag and the sipe bottom of the lateral sipe of the studless pneumatic tire that is the product is also zigzag, when the lateral force is input to the block from the road surface, the bent part There is a possibility that the strain will be concentrated on and cracks will occur. However, in this embodiment, the blade 28
Since the flask portion 28B of No. 2 has a linear shape, distortion is not concentrated when a lateral force is input. Therefore, the crack resistance of the pneumatic tire 10 can be improved. Since the stress at the sipe bottom portion 20B can be dispersed by making the cross-sectional shape of the sipe bottom portion 20B into a flask shape, the sipe bottom portion 20B itself also has an effect of suppressing the occurrence of cracks. .

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, tests were carried out on the studless pneumatic tire 10 of the present embodiment for the braking performance on ice, the presence or absence of block chipping, and the presence or absence of blade bending during vulcanization molding. The test results are shown in Table 1 below.

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 whose sipe bottom is not a flask cross section), a vulcanization mold (not shown) for manufacturing the same, and a comparative tire 3 (FIG. 8).
As shown in Fig. 4, a studless pneumatic tire having a block 42 with a lateral sipe 40 having a zigzag shape and a sipe bottom having a flask cross-sectional shape) and a vulcanization molding mold (not shown) for manufacturing the studless pneumatic tire. Was carried out for.

Further, the test results of the braking performance on ice are:
With tires attached to the vehicle, sudden braking is applied while traveling on a frozen special course at a loading condition of 20 km / h, and the distance from the point where the brake is applied to the point where it is stopped is measured. It is an index of the performance on ice.

Further, the test for the presence or absence of block missing is
Similarly, with an actual vehicle, the average speed of 60 km / h is taken on the asphalt pavement.
The method was to run for 20,000 km together with slalom running, and to check for block breaks.

[0038]

[Table 1] As can be seen from Table 1 above, the comparative tire 1 including the straight lateral sipe 32 whose sipe bottom has a cross-sectional shape that is not a flask shape and does not have a sipe bending portion, has good braking performance on ice and lacks blocks. Does not occur,
The blade is bent. Further, in the comparative tire 2 including the lateral sipe 36 that has a sipe bent portion but the cross-sectional shape of the sipe bottom is not a flask shape, blade bending does not occur, but the ice braking performance deteriorates. Block is missing. Furthermore, in the comparative tire 3 including the lateral sipe 40 having the sipe bent portion and the cross-sectional shape of the sipe bottom having the flask shape, the braking performance on ice was good and the blade bending did not occur, but the block chipping occurred. ing.
On the other hand, in the present embodiment, which has a zigzag shape having a sipe bent portion and the sipe bottom is formed in a linear shape and has a lateral sipe whose cross-sectional shape is a flask shape, the braking performance on ice is also good, Further, it can be seen that no block chipping or blade bending occurs.

Another embodiment will be briefly described below with reference to FIG. In the embodiment shown in FIG. 9, as shown in FIG. 9B, a pair of zigzag-shaped deformed sipes 46 are alternately formed on the block 44. In addition,
The lateral sipe 20 described above also has a zigzag shape, but the zigzag deformed sipe 46 of the present embodiment is different in that the interval between the peak and the valley is relatively narrow. Each zigzag deformation sipe 46
Has a sipe bent portion 48 at five locations, and the cross-sectional shape of two locations of the sipe bottom portion 46A and the other end of the sipe 46B is a flask shape. The sipe bottom 4
Both 6A and the other end 46B of the sipe are linearly formed.

FIG. 9A is a perspective view showing a blade 50 for forming the above-mentioned zigzag-shaped deformed sipe 46. As shown in this drawing, the blade 50 is formed in a zigzag shape having blade bent portions 52 at five positions. In addition, the cylindrical flask portion 5 is provided at two locations of the lower edge of the blade base 50A and the side edge on the free end side.
0B is provided.

According to the above-described embodiment, as in the above-described embodiments, the occurrence of blade bending during vulcanization molding is prevented, and the studless pneumatic tire manufactured by the vulcanization molding mold including the blade 50 is excellent. The performance on ice can be maintained at the same time.

Further, although the blade base 50A is formed in a zigzag shape, the flask portion 50B is formed in a linear shape so that the sipe bottom 46A of the zigzag deformed sipe 46 of the block 44 after molding is linear. ,
The crack resistance of the studless pneumatic tire 10 can be improved.

Further, since the zigzag-shaped deforming sipe 46 is also a one-sided opening 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 two-sided opening sipe. be able to.

Further, according to the present embodiment, by providing the cylindrical flask portion 50B not only on the lower end edge of the blade base 50A but also on the side edge on the free end side, the sipe other end 46B of the zigzag deformed sipe 46 is formed. Since the cross-sectional shape of is also a flask shape, it is possible to prevent cracks from occurring at the sipe other end 46B of the zigzag deformation sipe 46. Therefore, 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 46A. 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 46B of the zigzag deformed sipe 46 to be a flask shape, the drainage property at the sipe other end 46B of the zigzag deformed sipe 46 can also be improved.

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

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

[0047]

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.

Further, the vulcanization molding mold according to the present invention and the pneumatic tire manufactured using the vulcanization molding mold also have an excellent effect that the crack resistance of the commercialized studless pneumatic tire can be improved. Have.

[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 is a plan view of a block of a comparative tire 3 corresponding to FIG. 2 for explaining the effect of the present embodiment.

9A and 9B are perspective views of a blade and FIG. 9B is a plan view of a block according to another embodiment.

[Explanation of symbols]

 10 studless pneumatic tire 14 main groove 16 lug groove 18 block 18A block land portion 20 lateral sipe 20B sipe bottom portion 22 sipe bending portion 24 vulcanization molding mold 28 blade 28B flask portion 30 blade bending portion 44 block 46 zigzag deformation sipe (horizontal) Sipe) 48 sipe bent part 50 blade 52 blade bent part

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area B29K 105: 24 B29L 30:00

Claims (4)

[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 At the same time, a portion corresponding to the sipe bottom of the blade is made linear and its cross-sectional shape is made into a flask shape. 2. A pneumatic tire manufactured by using the vulcanization molding mold according to claim 1. 3. The lateral sipe in the pneumatic tire according to claim 2, wherein the lateral sipe is a one-sided sipe whose one end opens to the block end and the other end substantially ends in the block land portion. Pneumatic tires. 4. The pneumatic tire according to claim 3, wherein the cross-sectional shape of the other end of the lateral sipe is also flask-shaped.