JP5607466B2 - Tire vulcanization mold - Google Patents

Description

  The present invention relates to a tire vulcanization mold including a bead ring that forms a bead portion of a tire.

  In general, in a vulcanizing process of a pneumatic tire, a split mold or a segment mold in which a tread ring is divided in the circumferential direction is generally used. Such a mold includes an annular tread molding portion, a pair of side plates, and a bead ring that comes into contact with the side plates.

  In the vulcanization step, the molded green tire is inserted into the vulcanization mold, and heated and pressurized in a cavity formed by the vulcanization mold and the bladder to form the vulcanized tire. During this vulcanization, if the gas generated from the air or rubber composition remains between the inner surface of the vulcanization mold and the green tire, air is generated in the bear or inside of the tire surface, and the appearance quality and durability of the tire are increased. Will reduce the sex.

  On the other hand, grooved saw cuts and vent holes are often provided on the inner surface of the vulcanization mold so that air staying between the green tire and the inner surface of the mold is discharged out of the mold.

  Further, Patent Document 1 divides a bead ring forming a bead portion of a tire into a first divided bead ring 101 and a second divided bead ring 102, and a shim (thin plate) 103 is disposed therebetween to form a gap. Thus, a vulcanization mold that discharges air in the cavity is disclosed.

JP 2008-37053 A (paragraph numbers 0018, 0025, 0029, 0030, FIG. 2)

  However, when a vulcanization mold provided with a vent hole is employed, a large number of spews are formed on the tire surface as rubber enters the vent hole. Spew requires a lot of work to cut and remove, and the spew remaining in the vicinity of the bead part may impair the appearance quality of the product and may deteriorate the adhesion between the bead part and the rim. . In addition, it is easy for rubber residue and mold release agent to accumulate on the vent hole due to repeated use of the vulcanization mold, and in order to remove the rubber residue and release agent deposited on the vent hole, it is necessary to shorten the cleaning cycle of the vulcanization mold. There is.

  On the other hand, the tire vulcanization mold of Patent Document 1 does not produce spew or saw cut marks as compared with those provided with vent holes, improves the appearance of the tire, and adheres between the bead portion and the rim. In addition, it is possible to prevent the spew cutting / removing step and the cleaning operation of the rubber residue and the release agent clogged in the vent hole.

  However, even when the tire vulcanization mold of Patent Document 1 is adopted, a small amount of rubber enters the gap between the divided bead rings, so that a minute rubber projection line such as a marking line remains and the rubber enters. It is necessary to clean the split surface and shim of the split bead ring.

  An object of the present invention is to provide a tire vulcanization mold capable of improving the appearance of a product while reliably discharging air, and making maintenance such as cleaning easier.

To achieve the above object, a tire vulcanization mold according to the present invention includes a bead ring that forms a bead portion of a tire, and the bead ring is divided into a plurality of divided bead rings in the central axis direction. In addition, the inner peripheral edge of the divided surface is set to a part corresponding to the bead heel part of the bead part. In addition, the bead ring is provided with a plurality of springs for biasing the separated bead rings in a direction to be separated from each other and a plurality of stoppers for regulating the amount of separation between the divided bead rings separately arranged in the circumferential direction. The springs are arranged in a plurality of spring arrangement holes formed on the dividing surface of at least one of the divided bead rings.

According to the above configuration, since the spring that biases the divided bead rings in a direction to separate them is provided, the air in the cavity can be discharged with a gap between the divided bead rings until just before the mold clamping is completed. Moreover, after the mold clamping is completed, the gap between the split bead rings is closed against the urging force of the spring, so that the rubber of the green tire can be prevented from entering between the split bead rings during vulcanization. I can . In particular, even if the air remains unevenly, for example, when the green tire is tilted and inserted into the vulcanization mold, the mold clamping is advanced with the gap between the divided bead rings remaining. Can correct the inclination of the green tire. Thereby, air can be discharged while being dispersed in the entire circumferential direction, and product defects due to air remaining in one place can be more reliably prevented.

  In addition, a plurality of detachment preventions that regulate the amount of separation between the split bead rings are provided, and these detachment preventions are arranged separately from the springs, so that even if rubber penetrates around the springs, they will come off. The spring can be easily replaced without being interfered by the stop. And since a spring is arrange | positioned in a spring arrangement | positioning hole, a spring can be attached or detached only by inserting / extracting to this spring arrangement | positioning hole, and replacement | exchange of a spring can be made easier.

  Furthermore, since the spring arrangement hole is formed in the divided surface of the divided bead ring, the spring arrangement hole can also be used as an air reservoir for temporarily collecting the air discharged from the gap between the divided bead rings. Thereby, even when the gap between the divided bead rings is narrow and it is difficult to sufficiently exhaust the air to the outside of the mold, the air can be sufficiently discharged at least from the inside of the mold.

Further, an air discharge path is formed through which air can be discharged from the spring arrangement hole to the outside of the mold. According to this configuration, the air accumulated in the spring arrangement hole can be discharged from the air discharge path to the outside of the mold, so that the air in the cavity can be discharged more reliably.

  Further, it is possible to adopt a configuration in which the springs are arranged in a plurality of rows in the circumferential direction. According to this configuration, since the springs are arranged in a circumferential direction and in a plurality of rows, the divided bead rings can be stably biased, and the gaps between the divided bead rings can be made as uniform as possible. Here, the number of springs per row and the number of rows may be set as appropriate according to the required degree of air release and the conditions of mold clamping. In addition, since the spring arrangement hole is formed in a limited space on the dividing surface, in order to set the spring arrangement hole to a size that functions as an air reservoir, the number of rows of springs should be set to about three. Is good.

  When the springs are arranged in a plurality of rows in the circumferential direction, it is possible to employ a configuration in which the elastic modulus of the springs arranged on the outer peripheral side is set larger than the elastic modulus of the springs arranged on the inner peripheral side. According to this configuration, the split bead ring can be more stably biased by increasing the elastic modulus of the outer peripheral spring, and the gap for discharging the air while suppressing the tilt of the split bead ring. The green tire can be prevented from being bitten between the divided bead rings when the mold is clamped.

  As a configuration for setting the elastic modulus of the outer peripheral spring to be larger than the elastic modulus of the inner peripheral spring, a configuration in which the spring arranged on the outer peripheral side is set to have a larger diameter than the spring arranged on the inner peripheral side. Can be illustrated. Instead of setting the outer peripheral spring to a large diameter, various methods such as using a large diameter wire rod can be adopted.

  Moreover, the structure which formed deeper the spring arrangement | positioning hole which arrange | positions the spring arranged on the outer peripheral side than the spring arrangement | positioning hole which arrange | positions the spring arranged on the inner peripheral side is also employable. According to this structure, the capacity | capacitance as an air reservoir of the spring arrangement | positioning hole of an outer peripheral side can be raised rather than the spring arrangement | positioning hole of an inner peripheral side. As a result, a large-capacity air reservoir can be provided on the outer peripheral side where the pressure of the air that has entered the gap between the divided bead rings tends to decrease, so that air can be discharged more reliably from the inside of the mold.

  As described above, according to the present invention, the gap between the divided bead rings is opened by the biasing force of the spring until immediately before the mold clamping, and the gap between the divided bead rings is closed after the mold clamping. As a result, the air in the vulcanization mold is surely discharged to prevent the occurrence of vulcanization problems, and the rubber is prevented from entering the gap between the divided bead rings to improve the appearance of the product. In addition, maintenance such as cleaning of the vulcanization mold can be facilitated.

Sectional drawing of the principal part of the tire vulcanization mold according to the present invention Layout of bead ring spring Expanded cross-sectional view of the upper bead ring Expanded sectional view of the lower bead ring Another form of bead ring spring layout Expanded cross-sectional view of a conventional tire vulcanization mold

  Hereinafter, the form for implementing the tire vulcanization mold concerning the present invention is explained using a drawing.

  As shown in FIG. 1, the tire vulcanization mold 1 includes a tread ring 2 that forms a tread portion, an upper side plate 3 and a lower side plate 4 that form sidewall portions, and inner peripheries of the side plates 3 and 4. An upper bead ring 5 and a lower bead ring 6 that form a bead portion 8a of the tire, and the green tire 8 is set in a cavity between the inner surface and the bladder 7 provided on the inner side, Tires are vulcanized.

  The tread ring 2 is configured by, for example, connecting about 3 to 10 tread segments made of a metal material in the circumferential direction to form a ring shape. By moving outwardly, the mold is easily released without causing tread block chipping or the like. Further, the upper side plate 3, the lower side plate 4, the upper bead ring 5 and the lower bead ring 6 are formed in a ring shape made of, for example, a metal material, and are assembled integrally with the tread ring 2 to constitute the vulcanization mold 1. To do.

  As shown in FIGS. 1 to 4, the upper bead ring 5 and the lower bead ring 6 are divided into inner and outer divided bead rings 5 a, 5 b and 6 a, 6 b in the central axis direction, respectively. A plurality of springs 9 for urging them in a direction to separate the 5a, 5b and the divided bead rings 6a, 6b, a plurality of bolts 10 for preventing the separation of the separated bead rings, and the spring 9 are divided. The split surfaces 11a and 11b of the bead rings 5a and 5b and a plurality of spring arrangement holes 13 formed in the division surfaces 12a and 12b of the divided bead rings 6a and 6b are provided. The spring 9, the spring arrangement hole 13 and the bolt 10 are provided. Are arranged in the circumferential direction separately.

  The divided bead rings 5a, 5b and 6a, 6b are set such that the outer diameter of the inner divided bead rings 5a, 6a is smaller than the outer diameter of the outer divided bead rings 5b, 6b. A bead bottom portion of the green tire 8 is formed on the outer peripheral surface, and a bead side portion of the green tire 8 is formed on the outer peripheral portion of the outer divided bead rings 5b and 6b. As a result, the inner peripheral edges of the split surfaces 11 and 12 of the upper bead ring 5 and the lower bead ring 6 are located at portions corresponding to the bead heel portions 8b of the bead portions 8a of the tire.

  The springs 9 are circumferentially arranged in two rows at a pitch that divides the entire circumference of the upper bead ring 5 and the lower bead ring 6 into, for example, five equal parts, and the divided bead rings 5a and 5b and the divided bead rings 6a and 6b are respectively arranged. Energize uniformly in the direction of separation. This spring 9 forms a gap between the divided bead rings 5a and 5b and between the divided bead rings 6a and 6b until immediately before the mold clamping of the tire vulcanizing mold 1 is completed. The biasing force is set to such an extent that can be closed.

  Thus, until just before the mold clamping of the tire vulcanization mold 1 is completed, air or gas is passed from the inside of the vulcanization mold 1 to the outside through the gap between the divided bead rings 5a and 5b and between the divided bead rings 6a and 6b. After the mold clamping is completed, the gap is closed and the rubber is prevented from entering between the divided bead rings 5a and 5b and between 6a and 6b. Further, since the inner peripheral edges of the divided surfaces 11 and 12 are located at a portion corresponding to the bead heel portion 8b of the bead portion 8a of the tire, the bead heel portion in which the air is most likely to accumulate during vulcanization of the bead portion 8a of the green tire 8. Air is effectively discharged from the periphery of 8b.

  The springs 9 may be arranged at unequal intervals in the circumferential direction of the upper bead ring 5 and the lower bead ring 6, and are joints such as tire sidewalls, 2 plies, treads, 1 plies, liners, etc. The spring 9 can also be arranged at a part where the air of the part tends to accumulate.

  The bolts 10 are arranged in the circumferential direction at a pitch that divides the entire circumference of the upper bead ring 5 and the lower bead ring 6 into, for example, five equal parts, and the tips thereof are arranged on the inner divided bead rings 5a and 6a from the outer divided bead ring 5b. , 6b, and loosely fasten the divided bead rings 5a, 5b and the divided bead rings 6a, 6b.

  By loosely tightening the bolt 10, the gap between the divided bead rings 5a and 5b and between the divided bead rings 6a and 6b is closed between the head 10a of the bolt 10 and the inner divided bead rings 5a and 6a. For example, a margin 14 of about 3 mm is provided. Due to this margin 14, the divided bead rings 5a and 5b and the divided bead rings 6a and 6b are separated to, for example, about 3 mm.

  The spring arrangement hole 13 is formed in the inner and outer divided bead rings 5 a, 5 b and 6 a, 6 b, and the entire length thereof is set to be shorter than the free length of the spring 9. This spring arrangement hole 13 also functions as an air reservoir for temporarily storing air and gas discharged from the inside of the tire vulcanizing mold 1 to the outside, and the upper side plate 3, the lower side plate 4, the upper bead ring 5, and the like. The air and gas accumulated in the spring arrangement hole 13 are discharged to the outside of the mold through the air discharge path 15 formed in the lower bead ring 6.

  Next, how the tire is vulcanized using the tire vulcanization mold will be described. First, for example, a green tire 8 is placed horizontally on a green pedestal having a structure in which an iron pipe is formed in a ring shape, and the green tire 8 is lifted by a green lifting device called a loader, and then a tire vulcanization mold is used. 1 and the bladder 7 is disposed inside the green tire 8.

  When the tire vulcanization mold 1 is clamped, when the green tire 8 is set to be inclined due to the influence of the inclination of the green pedestal due to aging, for example, first, the upper and lower parts of the green tire 8 are respectively placed on the upper side. Contact bead ring 5 and lower bead ring 6. At this time, gaps are provided by the spring 9 between the divided bead rings 5a and 5b and between the divided bead rings 6a and 6b.

  As the mold clamping is advanced, the inclination of the green tire 8 is corrected and gradually becomes horizontal, and until the mold clamping is completed, between the divided bead rings 5a and 5b and between the divided bead rings 6a and 6b. The air hugged by the inclination of the green tire 8 is discharged.

  When the mold clamping is completed, the green tire 8 is in a horizontal state and air is sufficiently discharged, and the gaps between the divided bead rings 5a and 5b and the divided bead rings 6a and 6b are closed. Thereafter, the vulcanized tire is vulcanized and molded by heating and pressing through the bladder 7. At that time, rubber does not enter between the divided bead rings 5a and 5b and between the divided bead rings 6a and 6b, so that the appearance of the tire can be improved and the frequency of the cleaning operation of the rubber residue can be reduced.

  According to the above configuration, since the divided bead rings 5a, 5b and 6a, 6b are uniformly biased by the plurality of springs 9, when the tire vulcanization mold 1 is clamped, the entire inner periphery thereof is clamped. Air can be discharged uniformly from the product to prevent product defects due to residual air. Moreover, after the mold clamping is completed, the gap between the split bead rings 5a, 5b and 6a, 6b is closed against the urging force of the spring 9, so that the entry of rubber into the gap is prevented, and the product As a result, the tire vulcanization mold 1 can be improved in maintainability.

  Furthermore, since the spring arrangement hole 13 is communicated with the outside of the tire vulcanization mold 1 by the air discharge passage 15, the air inside the mold can be temporarily accumulated in the spring arrangement hole 13, and the air can be discharged to the outside of the mold. The air inside the mold can be discharged more reliably. Moreover, since the spring 9 and the spring arrangement hole 13 and the bolt 10 are arranged separately, the spring 9 can be replaced without being interfered with the bolt 10, and the maintainability of the tire vulcanization mold 1 can be further improved. .

  Here, the vulcanization mold according to the present invention was formed with a shim and a gap was formed in the bead ring for the three items of “rubber protrusion”, “product appearance defect” and “maintenance of vulcanization mold”. Compared with a tire vulcanization mold (Patent Document 1). The evaluation size is 195 / 65R15.

  Regarding the protrusion of rubber, in a tire vulcanized mold with a shim, the rubber slightly enters the small gap formed in the bead ring by arranging the shim. On the other hand, since the vulcanization mold of the present invention prevents the rubber from entering while discharging air from the gap between the bead rings, it is possible to prevent even a slight protrusion of the rubber.

  Regarding the defect of the product appearance, the tire vulcanized mold with shim can usually obtain a good product appearance, but if the rubber that has entered the bead ring slightly gets clogged, the air will not be discharged. There is a risk of defects in the appearance of the product. In contrast, the vulcanization mold of the present invention prevents rubber from entering the gaps in the bead ring, so that air can be reliably discharged to obtain a good product appearance.

  Regarding the maintainability of the vulcanization mold, the tire vulcanization mold with shims had 6000 tires that could be produced, and the time required for maintenance was 1 hour 30 minutes per surface. In contrast, the vulcanization mold of the present invention has 11,000 tires that can be produced (183% of the tire vulcanization mold with shims), and the time required for maintenance is 20 minutes per surface (with shims) 450% of the tire vulcanization mold).

  In addition, this invention is not limited to said embodiment, A change can be suitably added within the scope of the present invention. For example, instead of arranging the same springs 9 in two rows, the spring 16 arranged on the outer peripheral side is set to have a larger diameter than the spring 17 arranged on the inner peripheral side, and the elastic modulus of the spring 16 on the outer peripheral side is It can also be set larger than the elastic modulus of the inner spring 17. As a result, it is possible to prevent the inner divided bead rings 5a and 6a from being inclined, so that the green tire 8 which is once set and brought into contact with the bead rings 5 and 6 moves upward when the mold is clamped. Even in this case, the biting of the rubber can be prevented.

  Further, the spring arrangement hole 18 for arranging the outer peripheral side spring 16 is formed deeper than the spring arrangement hole 19 for arranging the inner peripheral side spring 17 so as to be provided on the outer peripheral side where the pressure of the discharged air is likely to be reduced. The function of the spring arrangement hole 18 as an air reservoir can be enhanced.

DESCRIPTION OF SYMBOLS 1 Tire vulcanization mold 2 Tread ring 3 Upper side plate 4 Lower side plate 5 Upper bead ring 5a Inner divided bead ring 5b Outer divided bead ring 6 Lower bead ring 6a Inner divided bead ring 6b Outer divided bead ring 7 Bladder 8 Green tire 8a Bead portion 8b Bead heel portion 9 Spring 10 Bolt 10a Head 11 Dividing surface 11a Dividing surface 11b Dividing surface 12 Dividing surface 12a Dividing surface 12b Dividing surface 13 Spring arrangement hole 14 Margin 15 Air exhaust path 16 Spring 17 Spring 18 Spring arrangement hole 19 Spring arrangement hole

Claims (5)

A tire vulcanization mold having a bead ring that forms a bead portion of a tire,
The bead ring is divided into a plurality of divided bead rings in the central axis direction, and the inner peripheral edge of the divided surface is set to a part corresponding to the bead heel part of the bead part,
In the bead ring, a plurality of springs for urging in a direction for separating the divided bead rings and a plurality of stoppers for regulating the amount of separation between the divided bead rings are provided separately arranged in the circumferential direction, respectively. The spring is arranged in a plurality of spring arrangement holes formed in the dividing surface of at least one divided bead ring ,
A tire vulcanization mold, wherein an air discharge path capable of discharging air from the spring arrangement hole to the outside of the mold is formed . The tire vulcanization mold according to claim 1 , wherein the springs are provided in a circumferential direction and arranged in a plurality of rows. The tire vulcanization mold according to claim 2 , wherein the elastic modulus of the spring arranged on the outer peripheral side is set larger than the elastic modulus of the spring arranged on the inner peripheral side. The tire vulcanization mold according to claim 2 or 3 , wherein the spring arranged on the outer peripheral side is set to have a larger diameter than the spring arranged on the inner peripheral side. Spring mounting holes to arrange a spring arranged on the outer peripheral side, according to claim 2, 3 or 4, characterized in that it is deeper than the inner peripheral side spring mounting holes to arrange a spring arranged in Tire vulcanization mold.

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