JP2017042957A - Manufacturing method of pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a pneumatic tire, which is capable of shaping an inner face of a tire into a prescribed shape and capable of performing efficient shaping at the time of vulcanization in a vulcanization device having a bladder as an inner die.SOLUTION: When a green tire T is set inside a mold 1 and inserting and inflating a vulcanization bladder 2 to the inside of the green tire T to press the green tire T toward an outer side in a radial direction of the tire for vulcanization molding, a rigid reinforcing ring 3 having a recessed part 3A and a protruded part 3B on its outer peripheral surface is interposed between the green tire T and the vulcanization bladder 2 in a region corresponding to a tread part T1 of the green tire T to perform shaping of the inner face of the tire in the tread part T1 of the green tire T based on the recessed part 3A and the protruded part 3B of the rigid reinforcing ring 3.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for manufacturing a pneumatic tire, and more specifically, in a vulcanizing apparatus having a bladder as an inner mold, it is possible to mold a tire inner surface into a desired shape and efficiently mold during vulcanization. The present invention relates to a method of manufacturing a pneumatic tire that can be performed.

  A pneumatic tire is generally manufactured by a vulcanizing apparatus having a bladder as an inner mold. Therefore, the tire inner surface is molded into a smooth shape by the bladder. On the other hand, it is required to mold the tire inner surface into a desired shape. For example, in order to improve the straight running stability during running, ribs extending in the tire circumferential direction are formed on the tire inner surface, or when installing information equipment, sensor devices, etc. on the tire inner surface, install them. Therefore, it is required to form a platform for the tire on the inner surface.

  As a method for performing molding on the tire inner surface, it is possible to form irregularities on the outer surface of the bladder and transfer the irregular shapes to the tire inner surface (see, for example, Patent Document 1). However, since the bladder is a shrinkable rubber bag, it is difficult to mold the tire inner surface into a desired shape.

  In addition, as another method of performing molding on the tire inner surface, it is possible to use a rigid core as an inner mold, to form irregularities on the outer surface of the rigid core, and to transfer the irregular shape to the tire inner surface ( For example, see Patent Document 2). However, the vulcanizing apparatus provided with a rigid core has the disadvantages of low versatility and high equipment costs.

  Further, as a method of attaching the device to the inner surface of the tire, a mold transfer member having a shape corresponding to the shape of the engagement receiving portion is installed on the inner surface of the raw tire, and after the raw tire is vulcanized and molded, the mold is formed from the vulcanized molded tire. It has been proposed to form an engagement receiving portion by removing the transfer member and attach a device using such an engagement receiving portion (see, for example, Patent Document 3). However, the operation of installing a mold transfer member for each engagement receiving portion on the inner surface of the tire and removing the mold transfer member after vulcanization is complicated, and it is not possible to efficiently perform the molding operation on the tire inner surface.

Japanese Patent Laying-Open No. 2015-20731 JP 2006-224377 A JP 2012-25319 A

  An object of the present invention is to provide an air that enables a tire inner surface to be molded into a desired shape in a vulcanization facility provided with a bladder as an inner mold, and allows the tire inner surface to be efficiently molded during vulcanization. It is in providing the manufacturing method of a entering tire.

  In order to achieve the above object, a method for producing a pneumatic tire according to the present invention comprises setting a green tire in a mold, inserting a vulcanizing bladder inside the green tire and inflating the green tire. When the vulcanization molding is performed by pressing toward the outer side in the tire radial direction, the rigid reinforcement having a recess and a protrusion on the outer peripheral surface between the green tire and the vulcanization bladder in a region corresponding to the tread portion of the green tire. By interposing the ring, the inner surface of the tire in the tread portion of the green tire is molded on the basis of the concave portion and the convex portion of the rigidity reinforcing ring.

  In the present invention, it becomes possible to mold various shapes on the inner surface of the tire by using a rigid reinforcing ring having a concave portion and a convex portion, and such a rigid reinforcing ring has a bladder as an inner mold. It is possible to use in and is highly versatile. Moreover, when the said rigidity reinforcement ring is used, the type | molding of a tire inner surface can be performed efficiently at the time of vulcanization | cure.

  In the present invention, the rigid reinforcing ring preferably includes a reinforcing wire extending in the circumferential direction. By including the reinforcing wire in the rigidity reinforcing ring, the rigidity in the circumferential direction of the rigidity reinforcing ring is secured, and the contour of the tire inner surface can be firmly formed.

  It is preferable that the concave portion and the convex portion of the rigid reinforcing ring extend continuously along the circumferential direction. Thereby, the convex part and recessed part corresponding to the recessed part and convex part of a rigidity reinforcement ring can be continuously formed along a tire circumferential direction.

  Moreover, it is preferable to interpose an auxiliary ring as an additional mold in the recess of the rigid reinforcing ring. The additional mold has flexibility to cope with various types of molding, and by using the additional mold, it is possible to perform shape processing for attaching components, sensors, and the like to the tire inner surface during vulcanization.

  Furthermore, it is preferable to provide an inclined surface on the surface that contacts the vulcanizing bladder at both ends so that both ends of the rigidity reinforcing ring gradually become thinner toward the outside in the width direction. Further, when the rigid reinforcing ring has a plurality of types of concave portions having different depths and has a thick portion and a thin portion whose thickness is changed according to the depth of the concave portion, It is preferable to provide an inclined surface on the surface that contacts the vulcanizing bladder at the stepped portion. By providing an inclined surface on such a rigid reinforcing ring, the vulcanizing bladder comes into contact with the rigid reinforcing ring without a step, and pressure is evenly transmitted to the green tire, so there is a delay in heat conduction. It is suppressed and the time required for vulcanization can be shortened. In addition, the thickness of the rigid reinforcing ring is reduced overall by providing the rigid reinforcing ring with a thick part and a thin part with the thickness changed in accordance with the depth of the concave portion. Contributes to shortening.

It is meridian sectional drawing which shows an example of the vulcanization | cure apparatus used for the manufacturing method of the pneumatic tire of this invention. It is sectional drawing which shows the vulcanization bladder in the state expanded at the time of vulcanization in the vulcanizer of FIG. It is a perspective view which shows the rigidity reinforcement ring in the vulcanizer of FIG. It is sectional drawing which shows the rigidity reinforcement ring of FIG. It is sectional drawing which shows the modification of a rigidity reinforcement ring. It is sectional drawing which shows the other modification of a rigidity reinforcement ring. It is sectional drawing which shows the further another modification of a rigidity reinforcement ring. It is a perspective view which shows an example of the additional type | mold suitably used with the manufacturing method of the pneumatic tire of this invention. It is sectional drawing which shows the additional type | mold of FIG.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 schematically shows a mold 1, a vulcanizing bladder 2, and a green tire T during vulcanization molding. FIG. 1 shows a state in which the green tire T is pressed against the inner surface of the mold 1 by the expansion of the vulcanizing bladder 2. The green tire T includes a tread portion T1, a side portion T2, and a bead portion T3.

  In the present invention, the rigidity reinforcing ring 3 is disposed between the green tire T and the vulcanizing bladder 2 in a region corresponding to the tread portion T1 of the green tire T. The rigidity reinforcing ring 3 is a cylindrical ring, and it is necessary that the stress required for a predetermined amount of tensile deformation in the circumferential direction is greater than the stress required for a predetermined amount of compressive deformation in the circumferential direction. is there. That is, the rigidity reinforcing ring 3 has a property that it is difficult to extend in the tire circumferential direction and is easily compressed.

  By fitting the rigid reinforcing ring 3 to the outer periphery of the vulcanizing bladder 2, when the vulcanizing bladder 2 expands during vulcanization molding, the rigid reinforcing ring 3 is difficult to extend in the circumferential direction and suppresses changes in its diameter. Therefore, the outer diameter of the vulcanizing bladder 2, in particular, the tread portion T <b> 1 is prevented from curling up unexpectedly and the outer peripheral shape of the vulcanizing bladder 2 is limited. That is, by using the rigidity reinforcing ring 3, the shape of the inner peripheral surface of the tire when the vulcanizing bladder 2 expands during vulcanization molding is limited, and the thickness in the tire radial direction in the region corresponding to the tread portion T1. It is possible to increase the dimensional accuracy by adjusting the height. For this reason, it is preferable that the rigidity reinforcement ring 3 has a larger tensile rigidity in the tire circumferential direction than that of the vulcanizing bladder 2 in the tire circumferential direction.

  Further, since the vulcanizing bladder 2 fitted on the rigidity reinforcing ring 3 is restricted from expanding in the tire radial direction, it is easy to expand in the opening of the rigidity reinforcing ring 3, that is, in the tire width direction. As a result, it is relatively slow to make contact with the inner surface of the mold, and it is difficult to apply sufficient pressing force. Can be subjected to heating and pressure treatment. That is, by using the rigidity reinforcing ring 3, it is possible to reduce the thickness of the tire shoulder portion to increase the dimensional accuracy and to shorten the vulcanization time.

  The rigidity reinforcing ring 3 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, vulcanized rubber close to the tire inner surface where vulcanization has progressed in the initial stage due to thermal expansion needs to reduce the circumference of the tire lumen. is there. Since the rigidity-enhanced ring 3 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 a failure such as buckling from occurring.

  The rigidity reinforcing ring 3 is a cylindrical ring, and the dimensions thereof are not particularly limited. However, the outer diameter of the rigidity reinforcing ring 3 is substantially equal to the inner diameter of the vulcanized tire, and the width of the rigidity reinforcing ring 3 is It is preferable that the width of the tread portion T1 of the vulcanized green tire T is substantially equal. As a result, it is possible to adjust the radially inner shape of the region corresponding to the tread portion T1 of the green tire T.

  The configuration of the rigid reinforcing ring 3 is not particularly limited as long as the tensile stress in the circumferential direction is greater than the compressive stress. Examples of the material constituting the rigidity reinforcing ring 3 include vulcanized rubber and resin. The thickness of the rigidity reinforcing ring 3 is not particularly limited, but is preferably 1 to 10 mm, more preferably 2 to 6 mm. If the thickness of the rigid reinforcing ring 3 is less than 1 mm, the effect of adjusting the shape of the tire inner peripheral surface during vulcanization molding may not be sufficiently obtained. On the other hand, if the thickness of the rigid reinforcing ring 3 exceeds 10 mm, there is a possibility that the effect of reducing the peripheral length after the middle stage of vulcanization molding cannot be obtained sufficiently. Furthermore, the optimal thickness of the rigid reinforcing ring 3 is not uniform depending on the shape and size of the tire to be vulcanized.

  The rigid reinforcing ring 3 preferably includes a reinforcing wire 4 (see FIGS. 4 to 7) extending in the circumferential direction. Examples of the reinforcing wire 4 include an organic fiber cord and a steel cord. Examples of organic fiber cords include polyester fiber cords, polyamide fiber cords, rayon fiber cords, aramid fiber cords, polyethylene naphthalate fiber cords, polyolefin ketone fiber cords, and acrylic fiber cords. The twisted structure of these fiber cords can be appropriately determined so that a predetermined tensile stress and compressive stress can be obtained when the rigid reinforcing ring 3 is used. Further, a reinforcing body is formed by winding the reinforcing wire 4 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 3 can be adjusted by the twisted structure of the reinforcing wire 4 and the tension at the time of winding.

  FIG. 2 shows a vulcanizing bladder 2 that is in an expanded state during vulcanization in a vulcanizing apparatus used in the method for producing a pneumatic tire of the present invention, and FIGS. 3 and 4 show a rigid reinforcing ring in the vulcanizing apparatus. 3 is shown. Concave portions 3 </ b> A and convex portions 3 </ b> B are formed on the outer peripheral surface of the rigid reinforcing ring 3 interposed between the green tire T and the vulcanizing bladder 2. As shown in FIG. 3, it is preferable that the concave portion 3 </ b> A and the convex portion 3 </ b> B of the rigidity reinforcing ring 3 continuously extend along the circumferential direction. Moreover, although not shown in figure, the rigidity reinforcement ring 3 can also form the recessed part 3A and the convex part 3B intermittently along the circumferential direction.

  As shown in FIG. 4, a plurality of reinforcing wires 4 are embedded in the rigid reinforcing ring 3. These reinforcing wires 4 are disposed along the bottom surface of the recess 3A and the top surface of the projection 3B. Although not shown, the reinforcing wire 4 can be arranged along the inner surface of the rigid reinforcing ring 3 as another embodiment.

  The depth of the recess 3A of the rigidity reinforcing ring 3 is not particularly limited, but at least the depth of the recess 3A is 0.5 mm or more, and preferably 1 mm to 5 mm. Further, the width of the recess 3A of the rigidity reinforcing ring 3 is not particularly limited.

  5-7 is sectional drawing which shows the modification of the rigidity reinforcement ring 3. As shown in FIG. In FIG. 5, a plurality of types of recesses 3 </ b> A having different depths are formed in the rigidity reinforcing ring 3. More specifically, the recess 3A located at the center in the width direction is deepest, and the other recesses 3A on both sides thereof are relatively shallow.

  In FIG. 6, as in the example of FIG. 5, a plurality of types of recesses 3 </ b> A having different depths are formed in the rigidity reinforcing ring 3. Further, the thickness of the rigid reinforcing ring 3 changes according to the depth of each recess 3A. That is, a thick portion 3C having a thickness t1 is formed in a portion where the recess 3A is deep, and a thin portion 3D having a thickness t2 is formed in a portion where the recess 3A is shallow. A step portion is formed at a location where the thick portion 3C and the thin portion 3D are adjacent to each other, and an inclined surface 3E is formed on a surface of the step portion that contacts the vulcanizing bladder 2. Further, in the cross section in the width direction of the rigidity reinforcing ring 3, both end portions of the rigidity reinforcing ring 3 are gradually thinner toward the outer side in the width direction, and inclined surfaces 3F are formed on the surfaces contacting the vulcanizing bladder 2 at the both end portions. Is provided. Note that the inclined surfaces 3F at both ends of the rigid reinforcing ring 3 can also be applied to the examples of FIGS.

  As a method for dealing with various types of molds, it is possible to interpose an auxiliary ring as an additional mold 6 in the rigid reinforcing ring 3 in the recess 3A of the rigid reinforcing ring 3. FIG. 7 is a cross-sectional view of the rigidity reinforcing ring 3 when an auxiliary ring is interposed as the additional mold 6 in the rigidity reinforcing ring 3. A recess 3 </ b> A is formed according to the cross-sectional shape of the additional die 6, and the additional die 6 is fitted into the recess 3 </ b> A of the rigidity reinforcing ring 3. At the time of vulcanization molding of the green tire T, the additional die 6 is fitted into the recess 3A of the rigidity reinforcing ring 3 and used.

  As shown in FIG. 8, the additional die 6 is formed with concave portions 6 </ b> A and convex portions 6 </ b> B that continuously extend in the circumferential direction. Although not illustrated, the additional die 6 is arranged along the circumferential direction. Thus, the recesses 6A and the protrusions 6B can be formed intermittently. As shown in FIG. 9, the additional die 6 preferably includes a plurality of reinforcing wire members 4 extending in the circumferential direction. The reinforcing wire 4 is disposed along the bottom surface of the concave portion 6A and the top surface of the convex portion 6B of the additional die 6. Although not shown, the reinforcing wire 4 can be disposed along the inner surface of the additional die 6. As the reinforcing wire 4 constituting the additional die 6, it is preferable to use the same organic fiber cord and steel cord as those of the rigid reinforcing ring 3.

  The thickness of the additional die 6 is not particularly limited. However, when the thickness of the rigid reinforcing ring 3 exceeds 10 mm, the effect of reducing the circumference after the middle stage of vulcanization molding is sufficiently obtained. Therefore, the thickness of the additional die 6 is defined in a range where the total thickness in the state where the additional die 6 is interposed in the recess 3A of the rigidity reinforcing ring 3 does not exceed 10 mm, preferably 3 It is good that it is ˜8 mm.

  Hereinafter, the manufacturing method of the pneumatic tire which uses the rigidity reinforcement ring 3 is demonstrated. The tire vulcanizing method in the method for producing a pneumatic tire according to the present invention is a state in which the rigidity reinforcing ring 3 is disposed between the green tire T and the vulcanizing bladder 2 in a region corresponding to the tread portion T1 of the green tire T. Set in the mold 1.

  Further, when the auxiliary ring is interposed as the additional mold 6, the additional mold 6 is fitted into the recess 3 </ b> A of the rigidity reinforcing ring 3. In this state, the rigid reinforcing ring 3 can be disposed between the green tire T and the vulcanizing bladder 2 and set in the mold 1.

  Next, the vulcanizing bladder 2 is expanded to press the green tire T against the mold 1 outward in the tire radial direction. In a state where the vulcanizing bladder 2 is inflated, a mold is formed in the region corresponding to the tread portion T1 of the green tire T based on the concave portion 3A and the convex portion 3B of the rigidity reinforcing ring 3, and in the tread portion T1 of the green tire T Mold the tire inner surface. Thus, the vulcanization molding of the green tire T is performed using the rigidity reinforcing ring 3 alone or in combination with the rigidity reinforcing ring 3 and the additional die 6.

  In the method for manufacturing a pneumatic tire described above, rigidity enhancement having a concave portion 3A and a convex portion 3B on the outer circumferential surface between the green tire T and the vulcanizing bladder 2 in a region corresponding to the tread portion T1 of the green tire T. By interposing the ring 3 and molding the tire inner surface in the tread portion T1 of the green tire T based on the concave portion 3A and the convex portion 3B of the rigid reinforcing ring 3, it is possible to mold various shapes on the tire inner surface. Become. Moreover, such a rigidity-enhanced ring 3 can be used in a vulcanization facility having a bladder as an inner mold, and is highly versatile. Moreover, when the said rigidity reinforcement ring 3 is used, the type | molding of a tire inner surface can be performed efficiently at the time of a vulcanization | cure.

  The rigid reinforcing ring 3 preferably includes a reinforcing wire 4 extending in the circumferential direction. Thereby, the rigidity of the circumferential direction of the rigidity reinforcement ring 3 is ensured, and the outline of a tire inner surface can be formed firmly.

  It is preferable that the concave portion 3A and the convex portion 3B of the rigid reinforcing ring 3 continuously extend along the circumferential direction. Thereby, the recessed part and convex part corresponding to the recessed part 3A and convex part 3B of the rigidity reinforcement ring 3 can be continuously formed along a tire circumferential direction.

  It is preferable to interpose an auxiliary ring as the additional die 6 in the recess 3A of the rigid reinforcing ring 3. The additional mold 6 has flexibility to cope with various types of molding, and by using the additional mold 6, it is possible to perform shape processing for attaching components, sensors, and the like to the tire inner surface during vulcanization.

  Furthermore, it is preferable to provide the inclined surfaces 3F on the surfaces that come into contact with the vulcanizing bladder 2 at both ends so that both ends of the rigidity reinforcing ring 3 become gradually thinner toward the outside in the width direction. Further, when the rigid reinforcing ring 3 has a plurality of types of recesses 3A having different depths and has a thick portion 3C and a thin portion 3D whose thickness is changed according to the depth of the recess 3A, these thick portions 3C It is preferable to provide the inclined surface 3E on the surface that contacts the vulcanizing bladder 2 at the step between the thin portion 3D and the thin portion 3D. By providing the inclined surfaces 3E and 3F on such a rigid reinforcing ring 3, the vulcanizing bladder 2 comes into contact with the rigid reinforcing ring 3 without any step, and the pressure is uniformly transmitted to the green tire T. Therefore, the delay in heat conduction is suppressed, and the time required for vulcanization can be shortened. Further, by providing the rigid reinforcing ring 3 with the thick portion 3C and the thin portion 3D, the thickness of which is changed according to the depth of the recess 3A, the thickness of the rigid reinforcing ring 3 is reduced overall. This also contributes to shortening of the vulcanization time.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, the scope of the present invention is not limited to these Examples.

  When manufacturing pneumatic tires of the same specification (tire size 205 / 55R16), vulcanization is performed by bladder surface processing or using a rigid core in the conventional examples 1 and 2, and in the examples 1 and 2. The pneumatic tires of Conventional Examples 1-2 and Examples 1-2 were manufactured by performing vulcanization molding using a rigid reinforcing ring.

  In addition, in the rigidity reinforcement ring of Example 1, the inclined surface is not provided in the both ends of the rigidity reinforcement ring (FIG. 5: level | step difference large). In the rigidity-enhanced ring of Example 2, an inclined surface is provided on the surface that contacts the vulcanizing bladder at the stepped portion between the thick-walled portion and the thin-walled portion whose thickness is changed according to the depth of the recess of the rigid-reinforced ring. At the same time, inclined surfaces were provided on the surfaces that contact the vulcanizing bladder at both ends so that the both ends of the rigid reinforcing ring gradually become thinner toward the outside in the width direction (FIG. 6: small step).

  These test tires were evaluated in terms of molding accuracy, manufacturing cost, versatility of the vulcanization method, and efficiency of heat conduction, and the results are shown in Table 1.

Molding accuracy, versatility of vulcanization method, efficiency of heat conduction:
The case where each of the above items is excellent is indicated by “◎”, the case where it is good is indicated by “◯”, and the case where it is bad is indicated by “X”.

Manufacturing cost:
A case where the manufacturing cost is very low is indicated by “で”, a case where the manufacturing cost is low is indicated by “◯”, and a case where the manufacturing cost is high is indicated by “x”.

  As can be seen from Table 1, by manufacturing a pneumatic tire using the rigidity-enhanced ring of the present invention, the tires of Examples 1 and 2 are accurately typed on the tire inner surface, and these tires are It was possible to manufacture at a low cost. Moreover, the manufacturing method of such a pneumatic tire is highly versatile.

DESCRIPTION OF SYMBOLS 1 Mold | dye 2 Vulcanization bladder 3 Rigid reinforcement ring 3A Concave part 3B Convex part 3C Thick part 3D Thin part 3E, 3F Inclined surface 4 Reinforcement wire 6 Additional type 6A Concave part 6B Convex part T Green tire T1 Tread part T2 Side part T3 Bead part

Claims (6)

  When a green tire is set in a mold and a vulcanization bladder is inserted inside the green tire and inflated to press the green tire outward in the tire radial direction, the green tire tread A rigid reinforcing ring having a concave portion and a convex portion on its outer peripheral surface between the green tire and the vulcanizing bladder in a region corresponding to a portion, and based on the concave portion and the convex portion of the rigid reinforcing ring. A method for producing a pneumatic tire, comprising: molding a tire inner surface in a tread portion of the green tire.   The method for manufacturing a pneumatic tire according to claim 1, wherein the rigidity reinforcing ring includes a reinforcing wire extending in a circumferential direction.   The method for manufacturing a pneumatic tire according to claim 1 or 2, wherein the concave portion and the convex portion of the rigid reinforcing ring extend continuously along a circumferential direction.   The method for manufacturing a pneumatic tire according to claim 3, wherein an auxiliary ring is interposed as an additional mold in the recess of the rigidity reinforcing ring.   The inclined surface is provided in the surface which contact | abuts the said vulcanization bladder in this both ends so that the both ends of the said rigidity reinforcement ring may become thin gradually toward the width direction outer side. The manufacturing method of the pneumatic tire in any one.   The rigidity reinforcing ring has a plurality of types of recesses having different depths, and has a thick portion and a thin portion whose thickness is changed according to the depth of the recess, and a step between the thick portion and the thin portion. The method for manufacturing a pneumatic tire according to claim 5, wherein an inclined surface is provided on a surface of the portion that contacts the vulcanizing bladder.

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