JP2016185637A - Tire vulcanization inner die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for vulcanizing a pneumatic tire without reducing design flexibility and productivity while enhancing the dimensional accuracy of the pneumatic tire.SOLUTION: A method for vulcanizing a tire comprises: setting a green tire T in a die 1; and pressing the green tire outside in the tire radial direction by inserting a bladder 2 into the green tire T to expand the bladder to vulcanize and mold the green tire. A tire vulcanization inner die 3 comprises: a rigid reinforcing ring 4 consisting of a cylindrical ring, interposed between the inner peripheral surface of a region corresponding to a tread portion of the green tire T and the outer peripheral surface of a region corresponding to the tread portion of the bladder 2; a connection end part 6 clamped in the central mechanism of a vulcanization molding machine together with the end portion of the bladder 2; and a mooring band 5 for coupling the rigid reinforcing ring 4 and the connection end part 6. A stress required for performing a predetermined amount of tensile deformation in the circumferential direction of the rigid reinforcing ring 4 is larger than that required for performing a predetermined amount of compressive deformation in the circumferential direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tire vulcanization inner mold used for vulcanization molding of a pneumatic tire.

  As a method of vulcanizing and forming a pneumatic tire, after setting a green tire inside the mold, a vulcanizing bladder is inserted inside the green tire, and steam or the like is injected, filled, and inflated. Tires are often pressurized and heated. However, in vulcanization molding using a vulcanizing bladder, it is possible that the components of the pneumatic tire will flow and not be arranged as designed. In such a case, the desired tire performance may not be exhibited. Moreover, in order to manufacture a high-performance pneumatic tire, it is necessary to further increase the arrangement accuracy of the tire constituent members.

  In order to increase the dimensional accuracy of a pneumatic tire and improve tire performance, a vulcanization method using a rigid core as an inner mold has been proposed (see, for example, Patent Document 1). However, in the vulcanization method using a rigid core, it is difficult to cope with the thermal expansion of the tire during vulcanization, the applicable tire shape is limited, and it is difficult to remove the vulcanized tire from the inner mold In addition to the low productivity, there is a problem that the manufacturing cost becomes high. For this reason, there has been a demand for a method for vulcanizing a pneumatic tire that increases the dimensional accuracy of the pneumatic tire and does not reduce the degree of freedom in design and productivity.

JP 2007-69497 A

  An object of the present invention is to provide an inner mold for tire vulcanization in which the degree of freedom in design and productivity are not lowered while increasing the dimensional accuracy of a pneumatic tire.

  An inner mold for tire vulcanization according to the present invention that achieves the above-mentioned object is obtained by setting a green tire in a mold and pressing the bladder from the inner side of the green tire to the outer side in the tire radial direction for vulcanization molding of the green tire. A rigid reinforcing ring composed of a cylindrical ring interposed between the inner peripheral surface of the region corresponding to the tread portion and the outer peripheral surface of the region corresponding to the tread portion of the bladder, together with the end portion of the bladder An inner mold for tire vulcanization having a connection end clamped by a central mechanism and a mooring band for connecting the rigidity reinforcing ring and the connection end, wherein a predetermined amount of tensile deformation is applied in the circumferential direction of the rigidity reinforcing ring. It is characterized in that the stress required to cause the stress is greater than the stress required to cause a predetermined amount of compressive deformation in the circumferential direction.

  Further, the tire vulcanizing method of the present invention is a tire vulcanizing method in which the green tire is set in a mold, a bladder is inserted inside the green tire and inflated to press the tire outward in the tire radial direction. The method is characterized in that the bladder is inflated with the inner mold for tire vulcanization of the present invention interposed between the inner peripheral surface of the green tire and the outer peripheral surface of the bladder.

  According to the inner mold for tire vulcanization of the present invention and the tire vulcanization method using the same, the tensile stress in the circumferential direction is between the inner peripheral surface of the tread portion of the green tire and the outer peripheral surface of the tread portion of the bladder. Because the reinforced molding ring is placed and the vulcanization molding is larger than the compressive stress, the outer diameter of the bladder is restrained from expanding to limit the shape of the inner peripheral surface of the tire and adjust the thickness in the tire radial direction. can do. In addition, the bladder is suppressed from expanding in the tire radial direction and increases in the tire width direction, so that the thickness of the tire shoulder can be reduced. Thereby, the dimensional accuracy of a pneumatic tire can be made high. Moreover, the connecting end of the inner mold for tire vulcanization is moored to the center mechanism of the vulcanizing machine together with the end of the existing bladder, and this connecting end and the rigid reinforcing ring are connected via a mooring band. In order to facilitate attachment / detachment of the rigid reinforcing ring to / from the green tire lumen so as to be linked to the expansion / contraction of the bladder, the productivity of vulcanization molding is maintained and the manufacturing cost is not deteriorated.

  Further, the tire vulcanization inner mold can have a shrinking means for reducing the diameter of the rigid reinforcing ring radially inward on the inner peripheral surface of the rigid reinforcing ring. By contracting means, pulling a plurality of locations radially inward in the circumferential direction of the rigidity-enhanced ring and reducing the diameter of the cylindrical ring while making it into a polygonal shape with irregularities, the bead part of the green tire The interference can be eliminated and the tire can be smoothly attached to and detached from the tire lumen.

  Further, a cylindrical inner mold having a truncated cone shape interposed between the inner peripheral surface of the region corresponding to the bead portion of the green tire and the outer peripheral surface of the region corresponding to the bead portion of the bladder, the outer side in the tire radial direction By placing rigid reinforcing wheels made of vulcanized rubber with embedded reinforcing wire extending to the mooring band, the pressing force on the bead portion of the bladder is made uniform and the shape of the inner peripheral surface of the bead portion is The dimensional accuracy can be increased by limiting. In addition, since at least unevenness (breathing grooves) of the bladder is secured between the outer peripheral surface of the bladder and the rigidity-enhanced wheel, it is easy to discharge the air trapped in the shoulder region and suppress the occurrence of tire failure caused by air. be able to. Further, since the bladder is not directly in contact with the bead portion of the green tire, the rough bladder can be suppressed and the life of the bladder can be extended.

  Further, the rigid reinforcing ring may be a ring obtained by covering a reinforcing body in which a reinforcing wire having a twisted structure is wound at least in the tire circumferential direction with an unvulcanized rubber and vulcanizing the same. Furthermore, it is preferable that the tensile rigidity in the tire circumferential direction of the rigidity reinforcing ring is larger than the tensile rigidity in the tire circumferential direction of the bladder. This rigid reinforcing ring can achieve deformation other than tensile in the circumferential direction with a weak force, can be easily removed from a vulcanized pneumatic tire, and can be used for repeated vulcanization molding.

  The tire vulcanizing method of the present invention can produce a high-quality pneumatic tire stably and at low cost by vulcanizing a green tire using the above-described rigidity-enhanced ring, thereby providing high dimensional accuracy.

It is a meridian direction sectional view showing typically an example of an embodiment of an inner mold for tire vulcanization of the present invention used at the time of vulcanization of a green tire. It is a perspective view showing typically an example of an embodiment when the inner mold for tire vulcanization of the present invention is expanded. It is a perspective view showing typically an example of an embodiment when the inner mold for tire vulcanization of the present invention shrinks. (A) (b) is the side view which looked at the rigidity reinforcement ring which comprises this invention from the tire axial direction, (a) is a diameter when a rigidity reinforcement ring expands, (b) is a rigidity reinforcement ring contracted. It is explanatory drawing which shows a mode when it diameters. It is a perspective view showing typically an example of an embodiment of a rigid reinforcement wheel which constitutes the present invention. It is a perspective view which shows typically an example of other embodiment when the internal mold for tire vulcanization of this invention expands in diameter.

  Hereinafter, an inner mold for tire vulcanization according to the present invention will be described based on an embodiment shown in the drawings.

  FIG. 1 is an explanatory view schematically showing a mold 1, a vulcanizing bladder 2 (hereinafter referred to as “blader 2”), and a green tire T during vulcanization molding. FIG. 1 shows a state where the green tire T is pressed against the inner surface of the mold 1 by expanding the bladder 2. The green tire T includes a tread portion T1, a side portion T2, and a bead portion T3.

  The tire vulcanizing inner mold 3 according to the present invention includes a rigidity reinforcing ring 4, a mooring band 5, and a connecting end 6. Moreover, you may have the rigidity reinforcement wheel 9 arbitrarily. The rigidity reinforcing ring 4 is disposed between an inner peripheral surface of a region corresponding to the tread portion T1 of the green tire T and an outer peripheral surface of a region corresponding to the tread portion T1 of the bladder 2. The rigidity reinforcing ring 4 is a cylindrical ring, and the stress required to cause a predetermined amount of tensile deformation in the circumferential direction needs to be greater than the stress required to cause a predetermined amount of compressive deformation in the circumferential direction. is there. That is, the rigidity reinforcing ring 4 has a property that it is difficult to extend in the tire circumferential direction and is easily compressed.

  By fitting the rigid reinforcing ring 4 to the outer periphery of the bladder 2, when the bladder 2 expands during vulcanization molding, the rigid reinforcing ring 4 is difficult to extend in the circumferential direction, and changes in its diameter are suppressed. The diameter, in particular, the crown portion (tread portion) is restrained from bulging out against a circle and restricts the outer peripheral shape of the bladder 2. That is, by using the rigid reinforcing ring 4, the shape of the inner peripheral surface of the tire when the bladder 2 expands during vulcanization molding is limited, and the thickness in the tire radial direction in the region corresponding to the tread portion is adjusted. The accuracy can be increased. For this reason, it is preferable that the rigidity reinforcement ring 4 has a tensile rigidity in the tire circumferential direction larger than that of the bladder 2 in the tire circumferential direction.

  Further, since the bladder 2 fitted with the rigidity reinforcing ring 4 is limited in expansion in the tire radial direction, the bladder 2 is easily expanded in the opening of the rigidity reinforcing ring 4, that is, in the tire width direction. As a result, since it is relatively slow to make contact with the inner surface of the mold and it is difficult to sufficiently apply the pressing force, it is sufficient for the shoulder region of the green tire that has been one of the causes of the long vulcanization time. Can be heated and pressurized. That is, by using the rigidity reinforcing ring 4, the thickness of the tire shoulder can be reduced to increase the dimensional accuracy and the vulcanization time can be shortened.

  The rigidity reinforcing ring 4 has a feature that in addition to a large tensile stress in the circumferential direction, a compressive stress in the circumferential direction is small. In the initial stage of tire vulcanization molding, vulcanization of rubber such as carcass and belt layer close to the tire inner surface proceeds, and vulcanization of the entire tire cross section including the inside of the tire proceeds after the next intermediate stage. As the vulcanization of the unvulcanized rubber proceeds, the volume of the rubber increases due to thermal expansion. For this reason, when vulcanization of the entire tire cross section proceeds after the middle stage, the vulcanized rubber close to the tire inner surface where vulcanization has progressed in the initial stage due to thermal expansion, the circumference of the tire lumen shrinks, Deforms radially inward. Accordingly, the rigidity-enhanced ring 4 whose circumference has been expanded by the expansion of the bladder 2 in the initial stage of vulcanization molding needs to be reduced in the middle stage and thereafter. Since the rigidity-enhanced ring 4 of the present invention has a small circumferential compressive stress, it can follow the behavior of the vulcanized rubber after the middle stage and can prevent failure such as buckling.

  The structure of the rigid reinforcing ring 4 is not particularly limited as long as the tensile stress in the circumferential direction has a characteristic greater than the compressive stress. Examples of the material constituting the rigidity reinforcing ring 4 include vulcanized rubber and resin. The thickness of the rigidity reinforcing ring 4 is not particularly limited, but is preferably 1 to 10 mm, more preferably 2 to 7 mm. If the thickness of the rigid reinforcing ring 4 is less than 1 mm, there is a possibility that the effect of adjusting the shape of the tire inner peripheral surface at the time of vulcanization molding cannot be obtained sufficiently. On the other hand, if the thickness of the rigid reinforcing ring 4 exceeds 10 mm, there is a possibility that the effect of reducing the circumference after the middle stage of vulcanization molding cannot be obtained sufficiently. Further, the optimum thickness of the rigidity reinforcing ring 4 is not uniform depending on the shape and size of the tire to be vulcanized.

  The rigidity reinforcing ring 4 is a cylindrical ring, and the size thereof is not particularly limited, but the outer diameter of the rigidity reinforcing ring 4 is substantially equal to the inner diameter of the vulcanized tire, and the width of the rigidity reinforcing ring 4 is It is preferable that the width of the tread portion of the vulcanized tire is substantially equal. Thereby, the shape inside the radial direction of the area | region corresponded to the tread part of a tire can be adjusted.

  1 illustrates a cylindrical rigid reinforcing ring 4 whose outer diameter is constant in the tire width direction, the outer diameter of the rigid reinforcing ring 4 is not limited to the illustrated example. For example, when manufacturing a pneumatic tire in which the inner peripheral edge of the tire cross section is linear, the rigid reinforcing ring 4 illustrated in FIG. 1 can be used as it is. On the other hand, when manufacturing a pneumatic tire in which the inner peripheral edge of the tire cross section is designed in an arc shape, the outer diameter of the rigidity reinforcing ring 4 can be changed in the tire width direction along the designed arc. That is, the shape of the rigidity reinforcing ring 4 may be determined according to the cross-sectional shape of the designed tire. Thereby, the design freedom of a tire can be made higher.

  Further, the rigid reinforcing ring 4 is preferably separable from the vulcanized tire and bladder. The rigidity reinforcing ring 4 is preferably a ring made of vulcanized rubber, for example. The rigid reinforcing ring 4 is preferably made of vulcanized rubber so that it does not adhere to unvulcanized rubber and bladder. Thereby, the mold release property of the vulcanized tire can be improved. The rigid reinforcing ring 4 can be easily peeled off from the inside of the vulcanized tire taken out from the mold 1 and taken out.

  The rigid reinforcing ring 4 can also be formed as a vulcanized ring obtained by covering a reinforcing body in which a reinforcing wire having a twisted structure is wound at least in the tire circumferential direction with an unvulcanized rubber. By constituting the rigid reinforcing ring 4 with vulcanized rubber made of a reinforcing wire having a twisted structure, the tensile stress in the circumferential direction is increased, the compressive stress in the circumferential direction is reduced, and the unvulcanized rubber and the bladder are not adhered. can do. Thereby, the mold release property of the vulcanized tire can be improved. The rigidity reinforcing ring 4 can be easily peeled off from the inside of the vulcanized tire taken out from the mold 1 and taken out.

  Examples of the fiber reinforcing material include polyester fiber, polyamide fiber, rayon fiber, aramid fiber, polyethylene naphthalate fiber, polyolefin ketone fiber, and acrylic fiber. The fiber reinforcing material may be thread-like or cloth-like, and the fiber direction is not limited. As a fiber reinforcement method, for example, there is a method in which a cloth soaked with rubber is laid on the rigidity reinforcing ring 4 and vulcanized. The fibers constituting the fiber reinforcing material preferably have an angle of 30 ° or more, more preferably 30 ° to 60 ° with respect to the circumferential direction of the rigid reinforcing ring. Thereby, the rigidity reinforcement ring 4 can be strengthened efficiently.

  The twisted structure of these fiber cords can be appropriately determined so that predetermined tensile stress and compressive stress can be obtained when the rigid reinforcing ring 4 is used. Further, a reinforcing body is formed by winding the reinforcing wire in a spiral shape in the tire circumferential direction while applying an appropriate tension. The tensile stress in the circumferential direction of the rigid reinforcing ring 4 can be adjusted by the twisted structure of the reinforcing wire 6 and the tension during winding. The rigid reinforcing ring 4 is obtained by covering and reinforcing a reinforcing body made of the above-described reinforcing wire by sandwiching it with a sheet of unvulcanized rubber. As a coating method with unvulcanized rubber, a reinforcing wire may be coated in advance with unvulcanized rubber, and this may be wound spirally in the tire circumferential direction.

  The material which comprises the rigidity reinforcement ring 4 is not specifically limited, What is necessary is just a rubber component which usually comprises the rubber composition for vulcanization bladders, and the rubber composition for tires. Examples of the rubber component include butyl rubber, silicon rubber, fluorine rubber, natural rubber, isoprene rubber, butadiene rubber, and styrene butadiene rubber.

  An inner mold 3 for tire vulcanization according to the present invention has a pair of connection end portions 6 on both inner sides in the tire radial direction of the rigid reinforcing ring 4, and the connection end portions 6 together with the end portion 2 e of the bladder 2 are vulcanized. Clamped to the center mechanism of the machine. The shape of the connecting end 6 may be clamped to the center mechanism of the vulcanizing machine together with the bladder end 2e, and the shape is not particularly limited. Preferably, it may be composed of an annular vulcanized rubber band. Further, the connection end 6 can be formed so as to wrap the end 2e of the bladder from the inside in the radial direction to the outside in the width direction.

  In the present invention, the rigid reinforcing ring 4 is connected to a pair of connecting end portions 6 by a plurality of mooring bands 5 as shown in FIG. By connecting with the mooring band 5, it is possible to increase the accuracy with which the rigidity reinforcing ring 4 is interposed between the inner peripheral surface of the tread portion T <b> 1 of the green tire and the outer peripheral surface of the tread portion of the bladder 2. Further, the rigidity reinforcing ring 4 follows the expansion / contraction of the bladder 2 and facilitates the operation of expansion / reduction.

  Examples of the material constituting the mooring band 5 include a vulcanized rubber sheet (band) in which organic fiber cords are covered with rubber, and a vulcanized rubber sheet (band) in which rubber is immersed in a woven fabric. The number of the mooring bands 5 to be arranged is not particularly limited. For example, the number of the mooring bands 5 is preferably 2 to 30, more preferably 8 to 16 on the circumference of the end in the width direction of the rigidity reinforcing ring 4. Good.

  Here, FIG. 2 shows that the tire vulcanization inner mold 3 is inserted into the lumen of the green tire T together with the bladder 2, and the bladder 2 is expanded while the distance between the pair of connection end portions 6 moored to the central mechanism is reduced. The tire vulcanization inner mold 3 is schematically shown. On the other hand, FIG. 3 shows a form when the tire vulcanizing inner mold 3 is inserted into the lumen of the green tire T or when the vulcanized tire is removed from the vulcanizer, and a pair of connections moored to the central mechanism. A state in which the inner diameter 3 for tire vulcanization and the bladder 2 are reduced in diameter by increasing the distance between the end portions 6 is schematically shown. In the present invention, it is preferable to have the contracting means 7 for reducing the diameter of the rigid reinforcing ring 4 radially inward on the inner peripheral surface of the rigid reinforcing ring 4. Thereby, as shown in FIG. 3, by pulling a plurality of locations radially inward in the circumferential direction of the rigid reinforcing ring 4, and reducing the diameter of the cylindrical rigid reinforcing ring 4 while making the shape of the cylindrical rigid reinforcing ring 4 into a polygonal shape having irregularities. The green tire can be smoothly attached to and detached from the tire lumen without interference with the bead portion T3 of the tire.

  4 (a) and 4 (b) are explanatory views schematically illustrating the contracting means 7, and FIG. 4 (a) shows a state in which the tire vulcanizing inner mold 3 has been expanded by the bulging diameter of the bladder, FIG. (B) shows a state where the inner diameter 3 for tire vulcanization is reduced in diameter by the action of the contraction means 7 in accordance with the diameter reduction of the bladder. FIG. 4A shows the form of the rigid reinforcing ring 4 and the contracting means 7 when the green tire is pressed against the mold surface from the inside during vulcanization, and it is expanded and expanded without wrinkles. On the other hand, in FIG. 4B, the contraction means 7 contracts during demolding (during the dry cycle), so that the rigidity reinforcing ring 4 is reduced in diameter while being regularly deformed into a polygonal shape having irregularities.

  The contraction means 7 is connected to the contraction means 7 via the coupling portion 8 with an interval in the circumferential direction of the rigidity reinforcing ring 4. The contraction means 7 may be any of a string shape, a band shape, and a sheet shape, and these can be formed by a rubber band having elasticity or a metal spring. The contraction means 7 needs durability against repeated deformation and heat resistance against heating. From this viewpoint, the contraction means 7 is preferably formed by a metal spring or the like.

  The form of the coupling | bond part 8 is not specifically limited, You may couple | bond in any form of a dotted | punctate form, a linear form, and a planar form. Examples of the connection method include adhesive fixing using an adhesive, heat fusion by heating, caulking, fastening, fitting, and the like. In particular, the rigidity reinforcing ring 4 and the contracting means 7 are preferably connected by a method such as fastening that is easy to replace.

  In the present invention, the rigid reinforcing wheel 9 can be disposed on the inner peripheral surface of the region corresponding to the bead portion of the green tire on the periphery of the mooring band 5 that connects the rigid reinforcing ring 4 and the connecting end portion 6. Further, the rigidity-enhanced wheel 9 can reinforce the connection with the connection end portion 6 by the inner mooring band 10 in addition to the mooring band 5. That is, the rigidity reinforcing wheel 9 is disposed so as to be interposed between the inner peripheral surface of the region corresponding to the bead portion T3 of the green tire and the outer peripheral surface of the region corresponding to the bead portion of the bladder 2. As shown in FIG. 5, the rigid reinforcing wheel 9 is a cylindrical inner mold having a truncated cone shape. The rigid reinforcing wheel 9 is made of vulcanized rubber in which a reinforcing wire 11 extending outward in the tire radial direction is embedded. Become. Accordingly, the rigidity-enhanced wheel 9 can increase the out-of-plane rigidity in the tire radial direction. By increasing the out-of-plane rigidity of the rigidity-enhanced wheel 9, when the bladder 2 expands during vulcanization molding, the pressing force on the bead portion T3 of the bladder 2 is made uniform, and the shape of the inner peripheral surface of the bead portion T3 And the dimensional accuracy can be increased. That is, it is possible to limit the shape of the inner peripheral surface of the tire and adjust the tire thickness in the bead portion region to increase the dimensional accuracy.

  Further, the rigid reinforcing wheel 9 is made of vulcanized rubber so as not to be bonded to the bladder and the green tire through the vulcanization process. Thereby, the detachability (release property) of the vulcanized tire from the mold can be improved. The rigid reinforcing wheel 9 can be easily peeled off from the inside of the vulcanized tire taken out from the mold 1 and taken out.

  As the reinforcing wire 11, for example, polyester fiber, polyamide fiber, rayon fiber, aramid fiber, polyethylene naphthalate fiber, polyolefin ketone fiber, acrylic fiber, or the like can be used. The reinforcing wire 11 may be thread-like or cloth-like. For example, there is a method in which a cloth soaked with rubber is overlapped on the rigidity reinforcing wheel 9 and vulcanized. The fibers constituting the fiber reinforcing material 11 are preferably at an angle of 10 ° or less, more preferably 0 ° to 5 ° with respect to the tire radial direction. Further, when the green tire T is vulcanized and further heated to expand its volume, the bead portion T3 can ensure a reduced diameter inward in the tire circumferential direction. The arrangement density of the reinforcing wire 11 in the rigidity reinforcing wheel 9 is not particularly limited, but is preferably 5 to 80/5 cm on the circumference in the center of the tire radial direction (height direction) of the main body. Preferably, it is 30-60 lines / 5 cm. By setting the arrangement density of the reinforcing wires 11 within such a range, the out-of-plane bending rigidity of the rigidity-enhanced wheel 9 can be ensured while facilitating expansion / contraction of the main body 4 following the expansion / contraction of the bladder 2.

  Further, by disposing the rigid reinforcing wheel 9 made of vulcanized rubber between the outer peripheral surface of the bladder 2 and the green tire T, at least irregularities (ventilation grooves) on the outer peripheral surface of the bladder 2 are between the rigid reinforcing wheel 9. Secured. As a result, air trapped between the bladder 2 inside the side portion T2 of the green tire during vulcanization can be easily discharged from the ventilation groove between the rigid reinforcing wheel 9 and the bladder 2 in the bead portion. It is possible to suppress the occurrence of a tire failure due to the above. In addition, you may form an unevenness | corrugation (ventilation groove | channel) in the internal peripheral surface of the rigidity reinforcement ring 9. FIG. That is, by providing a ventilation means between the rigid reinforcing wheel 9 and the bladder 2, tire failure due to air trapping during vulcanization can be suppressed. Since both the rigidity reinforcing wheel 9 and the bladder 2 are made of vulcanized rubber, the ventilation means is not easily crushed during vulcanization, and trapped air can be discharged efficiently. In particular, even when vulcanizing a flat tire or the like that easily causes air trapping on the side portion T2, by using the rigid reinforcing wheel 9, it is possible to easily discharge air and suppress a tire failure during vulcanization.

  Further, since the bead portion T3 of the green tire is not directly in contact with the bladder 2 by interposing the rigidity reinforcing wheel 9, it is possible to prevent the sulfur component from being transferred from the bead portion T3 of the green tire to the bladder 2. . For this reason, the rough bladder which a bladder deteriorates with a sulfur component can be suppressed, and a bladder lifetime can be lengthened.

  FIG. 10 is a perspective view illustrating an embodiment of the tire vulcanizing inner mold 3 including the rigidity reinforcing ring 4 and the rigidity reinforcing wheel 9. The rigid reinforcing ring 4 and the rigid reinforcing wheel 9 are connected to the connecting end 6 and the mooring band 5, and the connecting end 6 is clamped to the center mechanism of the vulcanizing machine together with the end 2 e of the bladder. . In addition to the mooring band 5, the rigid reinforcing wheel 9 and the connection end 6 are connected via an inner mooring band 10. The peripheral edge on the radially outer side of the rigid reinforcing wheel 9 may be either linear (annular) as shown in FIG. 10 or wavy (annular connected by a wavy line) as shown in FIG. By making the periphery of the rigid reinforcing wheel 9 corrugated, the trace of the rigid reinforcing wheel 9 on the inner peripheral surface of the vulcanized tire can be blurred.

  The inner mold 3 for tire vulcanization according to the present invention only needs to be vulcanized and molded together with the existing bladder 2 in the central mechanism of the vulcanizing machine, so that the conventional productivity is maintained and the manufacturing cost is deteriorated. There is nothing.

  Hereinafter, a method for vulcanizing a pneumatic tire using the tire vulcanizing inner mold 3 will be described. In the tire vulcanizing method of the present invention, a state in which the above-described rigidity reinforcing ring 4 is interposed between the inner peripheral surface of the region corresponding to the tread portion T1 of the green tire T and the outer peripheral surface of the bladder 2 is the mold 1. It is set inside and vulcanized by expanding the bladder 2. As described above, since the outer periphery of the bladder 2 is fitted with the rigidity reinforcing ring 4, the shape on the tire inner peripheral side is defined by the outer periphery shape of the rigidity reinforcing ring 4, and the pressing of the green tire on the shoulder portion is suppressed. It can work effectively.

  As a mold for setting the green tire, a mold 1 that can be divided into a plurality of parts can be preferably used. By using the mold 1 that can be divided into a plurality of parts, it becomes easy to set a green tire assembly having approximately the same diameter as that of the vulcanized tire in the mold 1. The number of divisions of such a sectional mold can be determined according to the tire shape and tire size.

  Since the pneumatic tire obtained by the tire vulcanizing method of the present invention has dimensional accuracy close to the designed value, the intended tire performance can be achieved more reliably. Pneumatic tires vulcanized and molded using an inner mold for vulcanizing tires can have a flat tread part and prevent the thickness of the central area of the tread part from becoming thin, making the thickness almost uniform. it can. Thereby, the rolling resistance of the pneumatic tire can be further reduced.

  In the conventional bladder vulcanization that does not use the tire vulcanization inner mold of the present invention, the shape accuracy of the vulcanized pneumatic tire is not always sufficient. However, there are advantages in that the obtained pneumatic tire has little damage to the carcass layer and the like, and the vulcanization cost is low.

  In contrast, in the vulcanization method using the inner mold for tire vulcanization, it is only necessary to moor the inner mold for tire vulcanization to the central mechanism of the vulcanization molding machine equipped with the existing bladder. Vulcanization molding can be performed at low cost simply by adding. Moreover, while maintaining the advantage of reducing damage to the carcass layer of the pneumatic tire, the shape accuracy of the tire can be greatly improved so as to have a dimensional accuracy close to the designed value.

  On the other hand, the vulcanization method that uses a rigid core as the inner mold provides the advantage of increasing the tire shape accuracy, but it cannot use existing equipment equipped with a bladder and requires the introduction of a new production line. In addition, the rigid core itself is very expensive. Moreover, since it is difficult to cope with the thermal expansion of the tire during vulcanization, there is a problem that the carcass layer of the obtained pneumatic tire receives a large damage.

DESCRIPTION OF SYMBOLS 1 Mold 2 Vulcanization bladder 3 Tire vulcanization inner mold 4 Rigid reinforcement ring 5 Mooring band 6 Connection end 7 Shrinking means 8 Joining part 9 Rigid reinforcement wheel 10 Inner anchoring band 11 Reinforcement wire T Green tire T1 Tread part T2 Side Part T3 Bead part

Claims (7)

  When the green tire is set in a mold and the bladder is pressed from the inside of the green tire to the outside in the tire radial direction and vulcanized and molded, an inner peripheral surface of a region corresponding to the tread portion of the green tire, and the tread of the bladder A rigid reinforcing ring formed of a cylindrical ring interposed between outer peripheral surfaces of a region corresponding to a portion, a connection end portion clamped to a central mechanism of a vulcanizing machine together with an end portion of the bladder, and the rigid reinforcing ring and An inner mold for vulcanizing a tire having a mooring band for connecting connection ends, and a stress required to cause a predetermined amount of tensile deformation in the circumferential direction of the rigidity reinforcing ring causes a predetermined amount of compressive deformation in the circumferential direction. An inner mold for vulcanizing a tire, characterized by being larger than the stress required to make it.   2. The tire vulcanization inner mold according to claim 1, further comprising shrinkage means for reducing the diameter of the rigid reinforcing ring radially inward on an inner peripheral surface of the rigid reinforcing ring.   A cylindrical inner mold having a truncated cone shape interposed between an inner peripheral surface of a region corresponding to the bead portion of the green tire and an outer peripheral surface of a region corresponding to the bead portion of the bladder, the tire radial direction The inner mold for tire vulcanization according to claim 1 or 2, wherein a rigid reinforcing wheel made of vulcanized rubber in which a reinforcing wire extending outward is embedded in the mooring band.   The rigid reinforcing ring is a ring obtained by covering at least a reinforcing wire having a twisted structure wound in the tire circumferential direction with an unvulcanized rubber and vulcanizing this. The inner mold for tire vulcanization according to any one of the above.   The inner mold for tire vulcanization according to any one of claims 1 to 4, wherein a tensile rigidity in the tire circumferential direction of the rigidity reinforcing ring is larger than a tensile rigidity in the tire circumferential direction of the bladder.   A tire vulcanizing method in which the green tire is set in a mold, and a bladder is inserted inside the green tire and inflated to press the tire radially outward to vulcanize the tire, A tire vulcanizing method comprising inflating the bladder with the tire vulcanizing inner mold according to any one of claims 1 to 5 interposed between a peripheral surface and an outer peripheral surface of the bladder. .   A pneumatic tire obtained by the tire vulcanizing method according to claim 6.

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