JP6789508B2 - Tire vulcanization bladder, pneumatic tire manufacturing method and vulcanizer - Google Patents

Description

The present invention uses a tire vulcanization bladder, which is arranged in the cavity of a raw cover during tire vulcanization and presses the raw cover against the inner wall of a vulcanization mold by expanding. The present invention relates to a method for manufacturing a pneumatic tire and a vulcanizer provided with the tire vulcanization bladder.

When manufacturing pneumatic tires, the raw cover is set inside the vulcanization mold, and the tire vulcanization bladder placed in the cavity of the raw cover is expanded to attach the raw cover to the inner wall of the vulcanization mold. It is vulcanized by heating and pressurizing while pressing it against the tire.

In the vulcanization of this raw cover, if air is caught between the expanding tire vulcanization bladder and the inner surface of the tire, defects such as bears will occur in the vulcanized tire. A tire vulcanization bladder 100 provided with a vent line 101 on the outer surface, which is a groove for bleeding air as shown in FIG. 6, is used (for example, Patent Document 1).

Japanese Patent No. 2589032

However, in recent years, in consideration of the durability of the bead portion of the tire, a tire in which the volume around the bead portion is increased by folding back the clinch rubber with the bead core and wrapping it around is used. In such a tire, a vent is used. Despite the use of a tire vulcanizing bladder provided with a line, bears due to air biting may occur around the bead portion of the tire after vulcanization. In addition, cracks may occur around the bead portion of the tire after vulcanization.

Therefore, an object of the present invention is to provide a vulcanization technique capable of more appropriately preventing the occurrence of bears and cracks in a tire after vulcanization.

The invention according to claim 1
A tire vulcanization bladder that is placed in the cavity of a raw cover in the vulcanization process of a pneumatic tire and presses the raw cover against the inner wall of the vulcanization die by expanding.
A plurality of first vent lines provided obliquely toward the central portion in the axial direction over the entire circumference of the region in contact with the bead portion to the central portion of the raw cover during expansion.
The area in contact with the bead portion of the raw cover when expanded is provided with one or more second vent lines provided along the circumferential direction so as to intersect the first vent line .
The tire vulcanization bladder is characterized in that the second vent line provided along the circumferential direction is provided so as to form a polygonal line shape that moves up and down in the axial direction.

The invention according to claim 2
The bladder for tire vulcanization according to claim 1, wherein the groove depth of the second vent line is 0.1 to 1.0 mm.

The invention according to claim 3
The tire vulcanization bladder according to claim 1 or 2, wherein the groove width of the second vent line is 0.1 to 1.0 mm.

The invention according to claim 4
The first to third aspects of the present invention, wherein the second vent line is provided in a region within 10 mm inward in the axial direction from a position where the raw cover comes into contact with the bead toe tip portion when expanded. The bladder for tire vulcanization according to any one item.

The invention according to claim 5
The tire addition according to any one of claims 1 to 4, wherein the polygonal line shape formed on the second vent line moves up and down at an angle of 1 to 5 ° in the axial direction. A bladder for vulcanization.

The invention according to claim 6
The tire vulcanization bladder according to any one of claims 1 to 5 , wherein the number of the second vent lines is 2 to 5.

The invention according to claim 7
Manufacture of a pneumatic tire by performing vulcanization molding of a raw cover using the tire vulcanization bladder according to any one of claims 1 to 6. The method.

The invention according to claim 8 is
The method for manufacturing a pneumatic tire according to claim 7 , wherein the raw cover is a raw cover having a structure in which a clinch rubber is folded back by a bead core and wound inside.

The invention according to claim 9
The method for manufacturing a pneumatic tire according to claim 8 , wherein the raw cover is a raw cover for a tire for a light truck vehicle.

The invention according to claim 10
A vulcanization mold and a tire vulcanization bladder are provided, and the raw cover is vulcanized by inflating the tire vulcanization bladder and pressing the raw cover against the inner wall of the vulcanization mold. A tire vulcanizer
A pneumatic tire vulcanizing apparatus, wherein the tire vulcanizing bladder is the tire vulcanizing bladder according to any one of claims 1 to 6 .

The invention according to claim 11
The vulcanization die is provided with a bead ring in contact with the bead portion of the raw cover.
A plurality of groove-shaped sulfur cuts to which air passing through the first vent line and the second vent line of the tire vulcanization bladder are supplied are provided on the bead ring at predetermined intervals in the circumferential direction. Ori,
The vulcanization of a pneumatic tire according to claim 10 , wherein a vent hole for discharging air that has passed through the sulfur cut to the outside of the vulcanization die is provided at one end of the saw cut. It is a device.

According to the present invention, it is possible to provide a vulcanization technique capable of more appropriately preventing the occurrence of bears and cracks in a tire after vulcanization.

It is a front view which shows typically the tire vulcanization bladder which concerns on one Embodiment of this invention. It is sectional drawing explaining the vulcanization using the tire vulcanization bladder which concerns on one Embodiment of this invention. It is an enlarged view of the vicinity of the bead portion in FIG. It is a perspective view which shows typically the tire vulcanized by the tire vulcanizing bladder which concerns on one Embodiment of this invention. It is an enlarged view of a part of the tire vulcanization bladder which concerns on one Embodiment of this invention. It is a front view which shows the conventional tire vulcanization bladder. It is sectional drawing explaining the vulcanization using the conventional tire vulcanization bladder. It is a perspective view which shows typically the tire vulcanized by the conventional tire vulcanization bladder.

Hereinafter, the present invention will be described with reference to the drawings based on the embodiments.

1. 1. Outline of the tire vulcanization bladder according to the present embodiment As a result of the present inventor's study to solve the above-mentioned problems, the clinch rubber B2 as shown in FIG. 7 is folded back at the bead core B1 and wound inside the tire. In the raw cover B having such a structure, a step may occur in the region indicated by the symbol X of the bead portion B3, specifically, the boundary between the tip of the clinch rubber B2 and the inner liner B5, and this step may be a bear or a crack. It turned out that it is causing the occurrence of.

Specifically, air tends to collect in such a step, and the air collected in this part does not easily escape from the vent line, so that air is caught between the tire vulcanization bladder 100 and the raw cover B. As shown in FIG. 8, the bear C1 may be formed on the tire C after vulcanization.

Further, in general, a mold release agent is applied to the surface of the tire vulcanization bladder to prevent the tire after vulcanization from adhering to the tire vulcanization bladder. If the tire C enters, the clinch rubber B2 may peel off from the inner liner B5 and crack C2 (see FIG. 8) may occur in the vulcanized tire C.

On the other hand, the tire vulcanization bladder according to the present embodiment has a new vent line (second vent line) along the circumferential direction of the tire vulcanization bladder in the region in contact with the bead portion of the raw cover when expanded. By providing the above, it is possible to eliminate the step between the tip of the clinch rubber and the inner liner during vulcanization and suppress the occurrence of bears and cracks.

2. 2. Details of the tire vulcanization bladder according to the present embodiment Next, the tire vulcanization bladder according to the present embodiment will be described in detail.

FIG. 1 is a front view schematically showing a tire vulcanization bladder according to the present embodiment. Further, FIG. 2 is a cross-sectional view illustrating vulcanization molding of the raw cover using the tire vulcanization bladder according to the present embodiment, and FIG. 3 is a partially enlarged view of FIG.

As shown in FIG. 1, the tire vulcanization bladder 1 according to the present embodiment is composed of a barrel-shaped main body 2 and flange-shaped edge portions 3 provided at the upper and lower ends of the main body 2. The flange-shaped edge portion 3 is attached to a tire vulcanizer (not shown). The main body 2 is a hollow elastic body, and by arranging it in the cavity of the raw cover B and supplying a heating and pressurizing medium, the main body 2 expands and the raw cover B is attached to the inner wall of the vulcanization die A. It is configured to press.

Further, on the outer surface of the tire vulcanization bladder 1 according to the present embodiment, a vent line (first vent line) 4A similar to the conventional one is formed over the entire circumference. The first vent line 4A is oblique toward the central portion in the axial direction of the main body portion 2 over the entire circumference of the region in contact from the bead portion to the central portion of the raw cover when the tire vulcanization bladder 1 is expanded. The air between the inner surface of the raw cover and the outer surface of the tire vulcanization bladder 1 is discharged to the outside through the first vent line 4A during vulcanization.

Then, the tire vulcanization bladder 1 according to the present embodiment is further separated from the first vent line 4A by a new vent line in the region Y in contact with the bead portion of the raw cover when the tire vulcanization bladder 1 is expanded. (Second vent line) 4B is provided. The second vent line 4B is provided along the circumferential direction so as to intersect the first vent line 4A.

As described above, by using the vulcanization bladder 1 provided with the second vent line 4B, it is possible to eliminate the step between the tip of the clinch rubber B2 and the inner liner B5 during vulcanization.

Specifically, as shown in FIG. 3, when the raw cover is vulcanized using the tire vulcanization bladder 1 according to the present embodiment, a step is formed between the tip of the clinch rubber B2 and the inner liner B5. Even if it occurs, the rubber of the bead portion B3 (the tip of the clinch rubber B2 and the inner liner B5) flows into the second vent line 4B during vulcanization, so that this step can be eliminated.

Since the air and the release agent can be dispersed along the second vent line 4B, it is possible to prevent bears and cracks from occurring in the tire after vulcanization.

Next, the specific structure of the second vent line 4B will be described. As shown in FIG. 2, the second vent line 4B of the tire vulcanization bladder 1 according to the present embodiment has a region Y in contact with the bead portion B3 of the raw cover B when expanded, that is, the bead toe tip portion B4 of the raw cover B. It is provided in a region in contact with a portion of a predetermined distance in the axial direction from the tire. The distance of the region Y in which the second vent line 4B is formed is preferably within 10 mm.

Further, it is preferable to appropriately change the specific aspect of the second vent line 4B according to the shape of the raw cover and the vulcanization die. For example, by increasing the depth, groove width, number, etc. of the second vent line 4B to increase the volume of the entire second vent line 4B, the space in which rubber can flow during vulcanization increases, so that it becomes more. The generation of steps can be appropriately suppressed.

On the other hand, when the tire vulcanization bladder according to the present embodiment is used, unevenness C3 (see FIG. 4) on which the second vent line 4B is transferred is formed on the inner surface of the tire after vulcanization. If the volume of the entire vent line 4B is increased too much, the unevenness C3 becomes conspicuous in the vulcanized tire C, which may result in poor appearance.

Therefore, for example, the groove depth of the second vent line 4B is preferably 0.1 to 1.0 mm, the maximum groove width is 0.1 to 1.0 mm, and the number of lines is preferably 2 to 5.

FIG. 5 is an enlarged view of a part of the tire vulcanization bladder according to the present embodiment. The second vent line 4B formed along the circumferential direction of the tire vulcanization bladder 1 is preferably provided in a polygonal line shape that moves up and down in the axial direction as shown in FIGS. 1 and 5. It is preferable that the polygonal line shape is formed up and down at an angle θ (see FIG. 5) of 1 to 5 ° in the axial direction.

Further, when the tire vulcanization bladder 1 according to the present embodiment is used in the tire vulcanization apparatus, as shown in FIG. 2, the air passing through the first vent line and the second vent line 4B is appropriately used. It is preferable that the bead ring A1 of the vulcanization mold A is provided with the sulfur cut A2 and the vent hole A3 so that the bead ring A1 can be discharged to the outside of the vulcanization mold A.

For example, a plurality of saw cuts A2 (for example, 16) are provided on the bead ring A1 of the vulcanization die A at predetermined intervals in the circumferential direction, and vent holes A3 are provided at one end of the saw cut A2. Be beaded.

As a result, the air that has passed through the second vent line 4B and the first vent line 4A can be guided to the vent hole A3 through the sulfur cut A2, and can be appropriately discharged from the vent hole A3 to the outside of the vulcanization die A. .. As a result, the air discharge capacity of the tire vulcanizing apparatus provided with the second vent line 4B on the tire vulcanizing bladder 1 is further improved, and the occurrence of bears and cracks in the tire after vulcanization is more reliably prevented. be able to.

Further, the vulcanization bladder according to the present embodiment can be preferably used for vulcanization of the raw cover in which the clinch rubber B2 is folded back by the bead core B1 as described above, but the vulcanization of the raw cover having another structure is possible. Can also be used for. Among the tires having the structure in which the clinching rubber B2 is folded back, it can be particularly preferably used for vulcanization of tires for light truck vehicles.

Hereinafter, the present invention will be specifically described based on Examples.

A. Experiment 1
First, Experiment 1 was conducted on the effect of providing the second vent line as in the above-described embodiment. In this experiment, the preferable dimensions of the second vent line are also investigated.

1. 1. Examples and Comparative Examples (1) Examples 1 to 4
As in the above embodiment, using a tire vulcanization bead in which five second vent lines 4B are provided so as to intersect the first vent line 4A in the region of the raw cover B in contact with the bead portion B3. 30 tires for light trucks were vulcanized. The width and depth of the second vent line 4B were set to the same dimensions, and the width and depth were changed in Examples 1 to 4 as shown in Table 1.

(2) Comparative Example Using the conventional tire vulcanization bladder shown in FIG. 6, 30 tires for light truck vehicles were vulcanized and molded.

2. 2. Evaluation The vicinity of the bead on the inner peripheral surface of the tire after vulcanization was visually observed, and if cracks were generated, the number of cracks generated was counted, and then the defect occurrence rate (%) was calculated. The results are shown in Table 1.

In the tires of the comparative examples, as shown in FIG. 8, some tires C after vulcanization had bears C1 and cracks C2, and the defect occurrence rate was 16%. On the other hand, in Examples 1 to 4, no bears or cracks were generated, and the tire C as shown in FIG. 4 was obtained. From this, it was confirmed that the occurrence of crack C2 can be appropriately prevented by providing the second vent line on the tire vulcanization bladder.

Further, comparing Examples 1 to 4, the occurrence of cracks was appropriately suppressed in Example 4, but the unevenness to which the second vent line was transferred was largely formed on the tire after vulcanization, and the appearance. It was found that the width and depth of the second vent line are preferably 0.1 to 1.0 mm due to the occurrence of defects.

B. Experiment 2
Next, Experiment 2 was conducted to find out the preferred number of second vent lines.

In Experiment 2, as shown in Table 2, vulcanization molding of the raw cover was performed in Examples 5 to 11 with different numbers of second vent lines of the tire vulcanization bladder. The width and depth of the second vent line were set to 0.1 mm based on the results of Example 1, and other conditions were set to the same conditions as in Experiment 1.

Then, the number of cracks and the defect occurrence rate were determined by the same procedure as in Experiment 1 described above. The results are shown in Table 2. Table 2 also shows the results of the comparative examples evaluated in Experiment 1.

From Table 2, it was confirmed that the probability of occurrence of bears and cracks was significantly reduced in all of Examples 5 to 11. Further, comparing Examples 5 to 11, it was confirmed that the number of the second vent lines 4B may be one, but the occurrence of bears and cracks can be reliably prevented by using two or more.

On the other hand, in Examples 10 and 11 in which the number of the second vent lines 4B exceeds 5, many irregularities to which the second vent lines 4B are transferred are formed on the vulcanized tire C, resulting in poor appearance. It was confirmed that the number of the second vent lines 4B is preferably 5 or less.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments. Various modifications can be made to the above embodiments within the same and equivalent scope as the present invention.

1,100 Tire vulcanization bladder 2 Main body 3 Flange-shaped edge 4A 1st vent line 4B 2nd vent line 101 Vulcanization mold A1 Vulcanization mold A1 Saw cut A3 Vent hole B Raw cover B1 Bead core B2 Clinch rubber B3 Bead part B4 Bead toe tip part B5 Inner liner C Tire C1 Bear C2 Crack C3 Concavo-convex X Area of boundary between clinch rubber tip and inner liner Y Area in contact with bead part of raw cover θ Angle of fold line shape with respect to circumferential direction

Claims (11)

A tire vulcanization bladder that is placed in the cavity of a raw cover in the vulcanization process of a pneumatic tire and presses the raw cover against the inner wall of the vulcanization die by expanding.
A plurality of first vent lines provided obliquely toward the central portion in the axial direction over the entire circumference of the region in contact with the bead portion to the central portion of the raw cover during expansion.
The area in contact with the bead portion of the raw cover when expanded is provided with one or more second vent lines provided along the circumferential direction so as to intersect the first vent line .
A tire vulcanization bladder characterized in that the second vent line provided along the circumferential direction is provided so as to form a polygonal line shape that moves up and down in the axial direction. The bladder for tire vulcanization according to claim 1, wherein the groove depth of the second vent line is 0.1 to 1.0 mm. The tire vulcanization bladder according to claim 1 or 2, wherein the groove width of the second vent line is 0.1 to 1.0 mm. The first to third aspects of the present invention, wherein the second vent line is provided in a region within 10 mm inward in the axial direction from a position where the raw cover comes into contact with the bead toe tip portion when expanded. The bladder for tire vulcanization according to any one item. The tire addition according to any one of claims 1 to 4, wherein the polygonal line shape formed on the second vent line moves up and down at an angle of 1 to 5 ° in the axial direction. Bladder for vulcanization. The tire vulcanization bladder according to any one of claims 1 to 5 , wherein the number of the second vent lines is 2 to 5. Manufacture of a pneumatic tire by performing vulcanization molding of a raw cover using the tire vulcanization bladder according to any one of claims 1 to 6. Method. The method for manufacturing a pneumatic tire according to claim 7 , wherein the raw cover is a raw cover having a structure in which a clinch rubber is folded back by a bead core and wound inside. The method for manufacturing a pneumatic tire according to claim 8 , wherein the raw cover is a raw cover for a tire for a light truck vehicle. A vulcanization mold and a tire vulcanization bladder are provided, and the raw cover is vulcanized by inflating the tire vulcanization bladder and pressing the raw cover against the inner wall of the vulcanization mold. A tire vulcanizer
A pneumatic tire vulcanizing apparatus, wherein the tire vulcanizing bladder is the tire vulcanizing bladder according to any one of claims 1 to 6 . The vulcanization die is provided with a bead ring in contact with the bead portion of the raw cover.
A plurality of groove-shaped sulfur cuts for supplying air passing through the first vent line and the second vent line of the tire vulcanization bladder are provided on the bead ring at predetermined intervals in the circumferential direction. Ori,
The vulcanization of a pneumatic tire according to claim 10 , wherein a vent hole for discharging air that has passed through the sulfur cut to the outside of the vulcanization die is provided at one end of the saw cut. apparatus.

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