JP4517625B2 - Tire vulcanization bladder - Google Patents

Description

  The present invention relates to a bladder used for tire vulcanization molding.

  More specifically, when a tire is vulcanized and molded using a bladder, the thickness of the tread center portion and the tire shoulder portion of the molded tire is different. Related to a tire vulcanization molding bladder (hereinafter sometimes simply referred to as a “bladder”) effective in suppressing the occurrence of a so-called “belt wave phenomenon” in which a belt member positioned in a undulation is bent. It is.

  Conventionally, as shown in FIG. 3, vulcanization molding of a pneumatic tire is performed by placing an unvulcanized tire 2 in a vulcanization molding mold including an upper mold 3 and a lower mold 4. A bladder 1 made of an inflatable elastic hollow body (usually made of rubber) is placed inside 2, and a pressure heat medium for vulcanization (for example, high-temperature and high-pressure steam) is blown into the bladder 1 so that the bladder 1 is blown. The unvulcanized tire 2 is pressed against the inner wall of the upper mold 3 and the inner wall of the lower mold 4 and heated for a predetermined time.

  As shown in FIGS. 3 and 4, the bladder 1 usually has a donut-like structure having flanges 5 at both ends and an inflatable elastic hollow body 6 made of rubber as described above. Yes. Reference numeral 7 denotes a mold inner diameter portion.

  When a tire is vulcanized and molded using such a bladder, as described above, a belt wave phenomenon in which the belt member located inside the tread rubber bends so as to wave is often generated.

  There are several possible causes for this, but one of them is the conventional bladder shape as shown in FIG. 4, and a vulcanized pressure heat medium (for example, high-temperature, high-pressure steam) is blown into the bladder for expansion. At the tread center part, it will be pressed with a stronger pressing force than the tire shoulder part, and this will push the rubber in the center part toward the shoulder part, and as a result, the tread center part It is thought that this unbalance causes the belt wave phenomenon.

  In order to suppress the occurrence of this belt wave phenomenon, the thickness of the tread center part in the bladder is made particularly thick, and the expansion speed of the thick part (tread center part) is reduced (except for the tread center part). (The part called “shoulder part”), and as a result, an invention for increasing the thickness of the tread center part of the tire has been proposed (Patent Document 1).

However, even in the present invention, the problem has not been completely solved, and there is a basic situation that it is difficult to produce with good controllability because it may involve a relative balance of subtle thicknesses. In the case of adopting for vulcanization, it was difficult to vulcanize and mold while obtaining the desired effect.
JP 2001-30258 A

  In view of the above points, the object of the present invention is due to the difference in thickness between the tread center portion and the tire shoulder portion of the molded tire when the tire is vulcanized using a bladder. Then, it is providing the tire vulcanization molding method effective in suppressing generation | occurrence | production of the belt wave phenomenon that a belt bends.

More specifically, an object of the present invention is to provide a novel tire vulcanizing bladder capable of producing the above-described effects.

A tire vulcanization molding bladder according to the present invention that achieves this object has the following configuration (1).
(1) A tire vulcanization molding bladder, wherein a bladder circumferential length CL of a portion contacting the tread center portion and a bladder circumferential length SL of a portion contacting the shoulder portion have the relationship of the following formula (a): In addition , the CL and the SL are larger than the circumference of the bladder in the flange portion, and the thickness of the thinnest portion of the bladder thickness is in the range of 4.0 to 7.0 mm. Tire vulcanization molding bladder.
0.8 ≦ CL / SL ≦ 0.95 (a)

The tire manufacturing method of the present invention has the following configuration (2) .
(2) A method for producing a tire, wherein the tire is vulcanized and molded using the tire vulcanizing bladder described in (1) .

  According to the first aspect of the present invention, when the tire is vulcanized using a bladder, the tread center portion and the tire shoulder portion of the molded tire have different thicknesses. Therefore, it is possible to provide a tire vulcanization molding bladder that is effective in suppressing the occurrence of the belt wave phenomenon of bending.

In addition, the thickness of the thinnest part of the bladder is within the range of 4.0 to 7.0 mm , providing a tire vulcanization molded bladder with excellent manufacturability and durability. It can be done.

According to the present invention in claim 2, when vulcanized molded using bladder tires, due to the wall thickness and its tread center portion and the tire shoulder portion in the tire which is molded to be different, the belt it is capable of providing a tire manufacturing method capable of manufacturing a tire to suppress the occurrence of belt wave phenomenon bends.

  Hereinafter, the present invention will be described in more detail.

In the tire vulcanization molding bladder according to the present invention, the bladder circumferential length CL of the portion that comes into contact with the tread center portion and the bladder circumferential length SL of the portion that comes into contact with the shoulder portion have the relationship of the following formula (a): It is configured.
0.8 ≦ CL / SL ≦ 0.95 (a)

  Here, the “tread center portion” means a surface portion located at the center of the outer peripheral surface where the tire groove is formed, and the “portion contacting the tread center portion” of the bladder is inflated in the bladder. The outer peripheral surface portion of the bladder that comes into contact with the above-described tread center portion when being subjected to vulcanization molding.

  Further, the “shoulder portion” refers to a region portion having an inclination existing between the above-described tread center portion and the side wall portion of the tire, and the “part contacting the shoulder portion” of the bladder is inflated in the bladder. This means the outer peripheral surface portion of the bladder that comes into contact with the above-described tread shoulder portion when being subjected to vulcanization molding.

  Note that it is up to the individual desired tire shape, etc. to determine exactly what is the “part that abuts the tread center” and where is the “part that abuts the shoulder” by looking at the bladder. However, there are some points that are difficult to say.

  With regard to this point, as a result of intensive studies by the present inventors, if each part is uniformly defined on the basis of the overall width length and the width center position of the bladder, and the prada is configured according to the idea of the present invention, In the tire vulcanization molding of the present invention, the knowledge that the molding as desired in the present invention can be realized almost completely is obtained. In the following, in the present invention, “the bladder circumference CL of the portion contacting the tread center portion” "," Bladder circumferential length SL of the portion in contact with the shoulder portion "will be described.

  That is, in the ladder according to the present invention, as shown in FIG. 1, FIG. 2 and FIG. 4, the “part abutting on the tread center part” means that the entire width of the bladder is W for the sake of convenience. An area extending by 0.1 W on the side side (an area having a width of 0.2 W as a whole), and “the bladder circumferential length CL of the portion in contact with the tread center portion” is a range portion having the width center of 0.2 W The outer peripheral length of the portion with the shortest peripheral length.

  In addition, “the bladder circumference SL of the portion that abuts against the shoulder portion” is more than the end portion of the “portion that abuts the tread center portion having a region having a width of 0.2 W as a whole” described above. The outer peripheral length of the portion in the portion located on the outer side by a width of 0.2 W on one side.

  In the tire vulcanization bladder according to the present invention, the CL and SL are configured to have a relationship of 0.8 ≦ CL / SL ≦ 0.95. In the vicinity of the center of the direction, it is formed by narrow three-dimensional molding so as to have a circumference of 0.8 times to 0.95 times that of both outer side positions.

  With such a configuration, when the tire is vulcanized using the blater of the present invention, when the pressure heat medium for vulcanization is blown into the bladder and expanded, the pressing force at the tread center portion is increased. The tire shoulder part is no longer stronger than this, and as a result, the rubber in the center part is not pushed toward the shoulder part. As a result, the rubber thickness of the tread center part and shoulder part is almost Equally balanced tire molding can be realized, and the occurrence of the belt wave phenomenon is suppressed.

  According to the various findings of the present inventors, the relationship between the bladder circumference CL and SL is particularly preferably in the range of 0.85 ≦ CL / SL ≦ 0.9. By making it within such a range, the intended effect of the present invention can be obtained more reliably.

In the bladder of the present invention, the thickness of the bladder (thickness of the rubber part) is determined by the inventors from the standpoints of manufacturability, durability of use, maintainability of the desired shape even when expanded, and the like. According to the above findings, it is important that the thickness at the thinnest portion is within a range of 4.0 to 7.0 mm . Since the three-dimensional uneven structure of the bladder of the present invention is more conspicuous than the conventional one, more preferably, the thickness at the thinnest part is within the range of 5.0 to 6.0 mm. is there. This is because, in order to surely obtain the desired effect of the present invention, it is important to be configured so as to obtain the initial form-imparting effect even during expansion.

  Hereinafter, based on an Example, the concrete structure and effect of the bladder of this invention are demonstrated.

The tires used for evaluation in this example share the following specifications.
Tire size: 195 / 85R16, rib pattern Tire outer diameter: 740 mm

  The outer diameter of the bladder = 530 mm, the thickness of the bladder = 4.0 mm, the overall width W of the bladder = 400 mm, and the schematic structure as shown in FIG. 1, CL (the bladder circumferential length of the portion contacting the tread center portion) is 410 mm, SL Manufactured by vulcanizing and molding 100 tires using the tire vulcanization molding bladder of the present invention (the bladder circumferential length of the portion in contact with the shoulder portion) is 510 mm and the CL / SL ratio is 0.8. The number of belt waves generated was confirmed.

  As a result, the occurrence of belt waves was 1 out of 100.

The outer diameter of the bladder = 530 mm, the thickness of the bladder = 7.0 mm, the overall width W of the bladder = 400 mm, and the schematic structure as shown in FIG. 2, CL (the circumference of the bladder contacting the tread center) is 485 mm, SL Manufactured by vulcanizing and molding 100 tires using the tire vulcanization molding bladder of the present invention (the bladder circumferential length of the portion contacting the shoulder portion) is 510 mm and the CL / SL ratio is 0.95. The number of belt waves generated was confirmed.
As a result, the occurrence of belt waves was 1 out of 100.

(Comparative Example 1)
The outer diameter of the bladder = 530 mm, the thickness of the bladder = 4.0 mm, the overall width W of the bladder = 400 mm, and the schematic structure as shown in FIG. 4, CL (the circumference of the bladder contacting the tread center) is 530 mm, SL Using a conventional tire vulcanization bladder with a circumference of the bladder contacting the shoulder portion of 510 mm and a CL / SL ratio of 1.04, 100 tires are vulcanized and manufactured. The number of belt waves generated was confirmed.
As a result, the generation of belt waves was 5 out of 100.

  As can be seen from the above results, by using the tire vulcanization molding bladder of the present invention, the belt wave occurrence rate can be significantly reduced from 5% to 1% of the conventional one, and the effect of the present invention. It can be seen that is remarkable.

  The bladder of the present invention relates to a tire manufacturing method that can effectively prevent the occurrence of a so-called “belt wave phenomenon” in which a belt member positioned inside a tread rubber bends so as to wave after the tire is vulcanized. In the tire manufacturing industry, it can be used in various tire manufacturing industries including automobiles.

FIG. 1 is a schematic longitudinal sectional model diagram illustrating an example structure of a tire vulcanization bladder according to the present invention. FIG. 2 is a schematic longitudinal sectional model diagram illustrating another example structure of a tire vulcanization bladder according to the present invention. FIG. 3 is a schematic model cross-sectional view illustrating an expanded state of a bladder when a tire is vulcanized and molded using a tire vulcanization molding bladder, and shows a state when a conventional tire vulcanization molding bladder is used. It is a conceptual explanation. FIG. 4 is a schematic vertical cross-sectional model diagram illustrating the structure of a conventional tire vulcanization molding bladder.

Explanation of symbols

1: Tire molding bladder 2: Unvulcanized tire 3: Upper mold 4: Lower mold 5: Flange 6: Elastic hollow body 7: Mold inner diameter portion CL: Bladder circumferential length SL of the portion in contact with the tread center portion : Bladder circumference W of the part that contacts the shoulder part W: Full width of the bladder for tire vulcanization molding

Claims (2)

A tire vulcanizing bladder, and the bladder perimeter CL abutting portion in the tread center portion, and a bladder perimeter SL abutting portion in the shoulder portion having a relation of the following formula (a), and The CL and the SL are larger than the circumference of the bladder in the flange portion, and the thickness of the thinnest portion of the bladder is in the range of 4.0 to 7.0 mm. Vulcanization molding bladder.
0.8 ≦ CL / SL ≦ 0.95 (a)
Here, the bladder circumferential length CL of the portion in contact with the tread center portion and the bladder circumferential length SL of the portion in contact with the shoulder portion are respectively defined as follows.
(A) A portion that abuts the tread center portion: W is the entire width of the bladder, and a region extending 0.1 W from the width center to both sides (region having a width of 0.2 W as a whole)
(B) Bladder circumferential length CL of the part in contact with the tread center part: The outer circumferential length of the shortest circumferential length in the range part of the width center 0.2W in (b) above ,
(C) Bladder circumference SL of the part that abuts against the shoulder part: Width on one side further than the end part of the "a part that abuts the tread center part having a width of 0.2 W as a whole" in (a) above The outer peripheral length in the portion located outside by 0.2 W , A tire vulcanization molding using the tire vulcanization molding bladder according to claim 1 .

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