Tire molding mold and tire manufacturing method

Abstract

To provide a mold for tire molding and a method for manufacturing a tire, capable of reducing a drive power required for driving segments at the initial stage of mold release of the tire.SOLUTION: A mold 1 for tire molding comprises: an annular tread molding part 20 divided into a plurality of segments 21 aligned in a circumferential direction; and inclination mechanisms 40 and 50 for inclining the segments 21 toward a radially outside when the tread molding part 20 is opened toward the radially outside. The inclination mechanisms 40 and 50 return the inclination of the segment 21 after the tread molding part 20 is opened.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tire mold and a tire manufacturing method. [Background technology]

[0002] Conventionally, a known tire molding mold used when manufacturing a tire by vulcanizing and molding an unvulcanized raw tire is one in which the annular tread molding portion (tread mold) that molds the tire tread is divided into multiple segments arranged in the circumferential direction, and each segment is configured to open and close by moving in the radial direction (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-326332 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-334740 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-149079 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the above-described conventional tire molding mold or tire manufacturing method, when the tire is released from the tread molding section after vulcanization molding, each segment moves radially outward while maintaining its orientation relative to the tire tread, which causes the entire tread design surface that forms the tread of each segment to simultaneously peel off from the tread, posing a problem in that a large driving force is required to drive the segment until it is released from the tire.

[0005] For example, in the initial stage of tire release, the tread design surface of the segment must be peeled off from the tread, and the segment protrusions corresponding to this pattern must be removed from the tire design surface pattern. Therefore, when the tread design surface of the segment is peeled off from the tread, a large driving force is required to release the adhesion between the tread design surface and the tread. Furthermore, there was a problem that a large driving force was required to drive the segment due to undercut resistance when the segment protrusions corresponding to this pattern are removed from the tire design surface pattern until the segment is released from the tire.

[0006] The present invention has been made in consideration of the above circumstances, and its object is to provide a tire molding mold and a tire manufacturing method that can reduce the driving force required to drive the segments in the early stages of tire demolding. [Means for solving the problem]

[0007] In order to achieve the above object, the tire mold according to the present invention comprises: an annular tread molding portion divided into a plurality of segments arranged in a circumferential direction; a tilting mechanism that tilts the segments radially outward when the tread molding portion is opened radially outward, The tilting mechanism restores tilt to the segments after the tread molding is opened.

[0008] According to the above configuration, it is possible to reduce the driving force required to drive the segments in the early stage of tire demolding.

[0009] Specifically, when the tread molding portion is opened radially outward of the segment, the segment is tilted radially outward, thereby reducing the driving force required to release the adhesion between the tread design surface and the tread when the tread design surface of the segment is peeled off from the tread. Furthermore, by returning the tilt of the segment to its original position after the tread molding portion is opened, the segment protrusions corresponding to the pattern can be pulled straight out from the tire design surface pattern until the segment is released from the tire, thereby reducing the undercut resistance when the protrusions are pulled out and reducing the driving force required to drive the segment.

[0010] The tire mold according to the present invention further comprises: The tilting mechanism may be adapted to restore tilt to the segments after the tread mold has opened and before the tread mold has fully separated from the tread of the tire.

[0011] According to the above configuration, by returning the inclination of the segments to their original position before the tread molding portion completely separates from the tire tread, any protrusions of the segments corresponding to the pattern can be pulled straight out from the tire's design surface pattern, thereby reliably reducing the undercut resistance when the protrusions are pulled out and reducing the driving force required to drive the segments.

[0012] The tire mold according to the present invention further comprises: The tilting mechanism includes: a rotation axis provided on one end side of the segment in a direction of an axis of the tread molding portion, the rotation axis being perpendicular to both the moving direction of the segment and the axis of the tread molding portion; a base member that supports the segment so as to be rotatable about the rotation axis; a first tilting mechanism that tilts the segments by rotating the segments about the pivot axis when the tread molding portion is opened; and a second tilting mechanism that, after the tread molding portion is opened, rotates the segment about the rotation axis to return the inclination of the segment to its original position.

[0013] According to the above configuration, the segment can be rotated around the rotation axis as a rotation center to tilt or return to a tilted state. In this case, the first tilting mechanism tilts the segment, and the second tilting mechanism returns the tilt of the segment.

[0014] The tire mold according to the present invention further comprises: The device may further include an outer ring disposed radially outside the segments and movable between a holding position that holds the segments in a specified position and a release position that allows the segments to tilt radially outward.

[0015] According to the above configuration, the outer ring can switch between a state in which the segments are held in a specified position and a state in which the segments are allowed to tilt radially outward.

[0016] The tire mold according to the present invention further comprises: The outer ring is a first inclined surface portion that biases the segment radially inward when the tread molding portion is closed; The tread molding may be closed by moving along the axis of the segment.

[0017] According to the above configuration, when closing the tread molding portion, it moves along the axial direction, and as this movement occurs, the first inclined surface portion of the outer ring biases the segments radially inward, moving the segments radially inward and closing them.

[0018] The tire mold according to the present invention further comprises: a rail portion that engages with an engaging groove formed in the segment when the tread molding portion is opened, and pulls the segment outward in the radial direction; the engagement groove and the rail portion are arranged along the inclination direction of the first inclined surface portion, The rail portion is A convex portion and a flat portion are formed at one end portion, the first tilting mechanism rotates the segment by biasing the segment radially outward with the convex portion; The second tilting mechanism may be configured to bias the segments radially outward by aligning the rail portions along the flat portions, thereby rotating the segments and returning the inclination of the segments to their original position.

[0019] According to the above configuration, the rail portion can rotate and tilt one end of the segment by urging the convex portion radially outward at one end of the segment. Furthermore, after tilting the segment, the rail portion can rotate the segment by urging the engaging groove radially outward and returning it to its original tilted state by aligning the engaging groove with the flat portion.

[0020] The tire mold according to the present invention further comprises: the outer ring has a second inclined surface portion that engages with the segments and pulls the segments radially inward when the tread molding portion is opened, the second inclined surface portion is disposed along the first inclined surface portion, The tilting mechanism includes: the first tilting mechanism includes a first link portion connected to one end of the segment and engaged with the second inclined surface portion; the second tilting mechanism includes a second link portion that is connected to an end of the segment other than the end to which the first link portion is connected and that is engaged with the second inclined surface portion, The first link portion is pulled by the second inclined surface portion to pull the segment radially outward to incline the segment, The second link portion may be pulled by the second inclined surface portion to pull the segment radially outward, thereby returning the inclination of the segment to its original position.

[0021] According to the above configuration, the second inclined surface portion can pull the first link portion radially outward to tilt the segment. Furthermore, after tilting the segment, the second inclined surface portion can pull the second link portion radially outward to return the inclination of the segment to its original position.

[0022] The tire mold according to the present invention further comprises: The first link portion may be released from engagement with the second inclined surface portion after the segment is inclined.

[0023] According to the above configuration, when the first link portion is released from its engagement with the second inclined surface portion, the second inclined surface portion pulls the first link portion radially outward to incline the segment, and then when the second inclined surface portion pulls the second link portion radially outward to return the inclination of the segment to its original position, the inclination of the segment can be quickly returned to its original position.

[0024] The tire mold according to the present invention further comprises: When the tread molding is opened, a first of the segments may be tilted, followed by a second of the segments.

[0025] According to the above configuration, it is not necessary to tilt all of the segments at the same time, and the maximum value of the driving force required to drive the segments can be reduced.

[0026] In order to achieve the above object, a tire manufacturing method according to the present invention comprises: A tire manufacturing method using a tire mold having an annular tread molding portion divided into a plurality of segments arranged in a circumferential direction, a first step of inclining the segments radially outward of the tread molding portion when opening the tread molding portion after vulcanization molding of the unvulcanized raw tire; and a second step of reversing the tilt of the segments after the tread molding is opened.

[0027] The tire manufacturing method according to the present invention further comprises: The second step may be performed after the tread molding portion is opened and before the tread molding portion is completely separated from the tread of the tire.

[0028] According to the above method, it is possible to achieve the same functions and effects as the above-mentioned tire molding mold. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a cross-sectional front view of a tire mold according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of a tread molding portion in a plan view. [Figure 3] FIG. 2 is an enlarged cross-sectional view of a main part of the tire mold according to the first embodiment, as viewed from the front. [Figure 4] FIG. 3 is an enlarged cross-sectional view of the lower part of one segment in the first embodiment, as seen from the front. [Figure 5] FIG. 3 is a view of one segment in the first embodiment as viewed from the outside in the radial direction of the tread molding portion. [Figure 6] FIG. 2 is a cross-sectional view as seen from the front, showing a state of a main part of the tire mold at the initial stage of tire release in the first embodiment. [Figure 7] FIG. 7 is a cross-sectional front view showing the state of the main parts of the tire mold in a state where the tire has been further released from the state shown in FIG. 6. [Figure 8] FIG. 2 is a cross-sectional front view showing the state of the main parts of the tire mold after the tire has been released from the mold. [Figure 9] FIG. 2 is a cross-sectional view of the tire mold from the front, showing the main parts of the tire mold with the tread molding portion fully open. [Figure 10] FIG. 3 is an enlarged cross-sectional view of a front view showing a detailed structure of a main part of a tire mold according to a modified example of the first embodiment. [Figure 11] FIG. 10 is an enlarged cross-sectional view of a main part of a tire mold according to a second embodiment, as viewed from the front. [Figure 12] 12 is a cross-sectional view taken along the line AA in FIG. 11. [Figure 13] 12 is a cross-sectional view of FIG. 11 taken along line B-B. [Figure 14] FIG. 10 is a cross-sectional front view showing the state of the main parts of the tire mold at the beginning of tire release in the second embodiment. [Figure 15] FIG. 15 is a cross-sectional front view showing the state of the main parts of the tire mold in a state where the tire has been further released from the state shown in FIG. 14. [Figure 16] FIG. 2 is a cross-sectional front view showing the state of the main parts of the tire mold after the tire has been released from the mold. DETAILED DESCRIPTION OF THE INVENTION

[0030] (First embodiment) The tire mold and tire manufacturing method according to the present embodiment will be described in detail below with reference to the drawings, in which the same reference numerals are used to designate common members and parts.

[0031] A tire molding mold 1 according to one embodiment of the present invention shown in FIG. 1 is used to manufacture a tire 2 by molding a raw tire made mainly of unvulcanized (before vulcanization) synthetic rubber into a predetermined shape while vulcanizing it.

[0032] The tire 2 is a hollow tire made mainly of synthetic rubber, having a pair of sidewalls 2a, 2b and a tread 2c, and formed in a shape with a space inside that is filled with a gas such as air or nitrogen.

[0033] The tire mold 1 includes a sidewall molding portion 10 and a tread molding portion 20.

[0034] The sidewall molding portion 10 can be configured to include, for example, a circular lower sidewall molding portion 11 fixed to the upper surface of the lower container 3, and a circular upper sidewall molding portion 12 fixed to the lower surface of the upper container 4.

[0035] The sidewall molding portion 10 can arrange (store) an annular tire 2 or a raw tire between the lower sidewall molding portion 11 and the upper sidewall molding portion 12 in a position where its central axis is coaxial with the central axis O of the sidewall molding portion 10.

[0036] The lower sidewall molding portion 11 has an upwardly facing lower sidewall design surface 11a in a circular ring shape centered on the central axis O, and the lower sidewall design surface 11a can be used to mold the outer surface of one of the sidewalls 2a of the tire 2 or the raw tire (the side facing downward in Figure 1).

[0037] Similarly, the upper sidewall molding portion 12 has a downward-facing upper sidewall design surface 12a in a circular shape centered on the central axis O, and the upper sidewall design surface 12a can be used to mold the outer surface of the other sidewall 2b of the tire 2 or the raw tire (the side facing upward in Figure 1).

[0038] The sidewall molding section 10 is opened by the upper container 4 moving upward relative to the lower container 3 from the position shown in Fig. 1 (in the direction in which the two move away from each other along the center axis of the tire 2), and the tire 2 is released from the sidewall molding section 10. Meanwhile, by the upper container 4 moving downward to its original position shown in Fig. 1, the sidewall molding section 10 is closed from the open state to a state in which the tire 2 or raw tire can be molded.

[0039] The configuration of the sidewall molding section 10 can be changed as appropriate, for example, so that the lower container 3 moves downward relative to the upper container 4 to open it.

[0040] The tread molding portion 20 has an annular shape coaxial with the sidewall molding portion 10. The tread molding portion 20 is disposed adjacent to and radially outward from the lower sidewall molding portion 11 and the upper sidewall molding portion 12. The inner peripheral surface of the tread molding portion 20 facing radially inward forms a tread design surface 20a that molds the outer peripheral surface of the tread 2c of the tire 2.

[0041] As shown in FIG. 2 , the tread molding portion 20 is divided into a plurality of segments 21 arranged in the circumferential direction. Each segment 21 has an arc shape in a plan view. The segments 21 are combined in the circumferential direction to form the tread molding portion 20, which as a whole becomes a circular mold. In this embodiment, the tread molding portion 20 is divided into nine segments 21, each having the same circumferential length. Note that the number of segments 21 divided into the tread molding portion 20 in the circumferential direction is preferably between 7 and 13, but is not limited to this and can be changed as appropriate.

[0042] As shown in FIG. 3, in this embodiment, each of the plurality of segments 21 that constitute the tread molding portion 20 has a holder 22 and a design surface divided mold portion 23.

[0043] The holder 22 can be formed by cutting a block of metal such as low carbon steel.

[0044] The design surface divided mold section 23 is a part that constitutes the tread design surface 20a that forms the tread 2c of the tire 2, and is arc-shaped in plan view, with the surface facing radially inward constituting a part that is divided in the circumferential direction of the tread design surface 20a. The design surface divided mold section 23 is disposed radially inside the corresponding holder 22 and is fixed to the holder 22 using fixing members such as bolts (not shown).

[0045] The design surface divided mold section 23 can be configured such that the tread design surface 20a is provided with a plurality of protrusions 24 that protrude radially inward from the tread design surface 20a along the radial direction. The plurality of protrusions 24 are used to form grooves, sipes, etc. that form the tread pattern 2d in the tread 2c of the tire 2 during vulcanization molding. The plurality of protrusions 24 can have various shapes or lengths corresponding to the tread pattern 2d, such as those that extend in the tire width direction or those that extend in the tire circumferential direction.

[0046] The design surface divided mold part 23 is preferably formed by casting a metal material with high thermal conductivity, such as an aluminum alloy. In this case, for example, a rib-shaped or blade-shaped protrusion 24 made of steel may be integrally formed with the design surface divided mold part 23 when the design surface divided mold part 23 is cast.

[0047] As shown in Fig. 3, each segment 21 is provided with a rotation shaft 5 at one end side in the axial direction of the tread molding section 20 (the lower end side in the case shown in Fig. 3), the rotation shaft 5 being perpendicular to both the movement direction (radial direction) of the segment 21 and the axial center of the tread molding section 20. In this embodiment, as an example, a case is described in which the rotation shaft 5 is provided at the lower end portion of the holder 22. The rotation shaft 5 may also be provided in the design surface divided mold section 23.

[0048] An individual base member 6 corresponding to the segment 21 is disposed below each segment 21. The base member 6 supports the rotation shaft 5, thereby supporting the segment 21 so that it can rotate freely around the rotation shaft 5. In other words, the segment 21 can rotate freely around the rotation shaft 5 relative to the base member 6.

[0049] After the tire 2 is vulcanized and molded with each segment 21 in a specified position, the tread molding section 20 can be opened so as to release the tread 2c from the tread design surface 20a by rotating each segment 21 radially outward from the specified position around the rotation axis 5.

[0050] In this embodiment, as shown in Fig. 4, the tire mold 1 is provided with guide rails 25 that are supported by the lower container 3 and the lower sidewall molding portion 11 and extend along the radial direction of the segments 21. The guide rails 25 support the base member 6 so that it can move freely in the radial direction of the tread molding portion 20. This allows the base member 6 to move in the radial direction around the axis of the tread molding portion 20 (center axis O, see Figs. 1 and 2).

[0051] 4, a slide spring member 26 is disposed between the base member 6 and the lower sidewall molding portion 11 to bias the base member 6 radially outward from the tread molding portion 20. Each segment 21 is biased radially outward by the corresponding slide spring member 26. When the base member 6 moves radially, the segments 21 supported thereby also move radially together with the base member 6.

[0052] Between each segment 21 and the base member 6 corresponding to that segment 21, an external force applying mechanism 30 is provided which applies an external force to the segment 21 in a direction that causes the upper end side of the segment 21 to move radially outward around the pivot axis 5 when the tread molding section 20 is opened radially outward after the tire 2 has been vulcanized and molded.

[0053] In this embodiment, the external force imparting mechanism 30 is configured to include a rotation spring member 31 that imparts a spring force as an external force to the segment 21. Note that the external force imparting mechanism 30 is not limited to a configuration including a rotation spring member 31 that imparts a spring force as an external force to the segment 21, and can also be configured to impart an external force to the segment 21 by a drive source such as an air cylinder.

[0054] More specifically, as shown in Fig. 4, the external force exerting mechanism 30 includes a shaft 32 fixed to the upper surface of the base member 6 in a vertical position extending in the up-down direction. The shaft 32 is inserted into a hole 22a formed in a holder 22 constituting the segment 21, and a flange 33 formed on the upper end of the shaft 32 is disposed in the hole 22a. The rotation spring member 31 is a compression coil spring, and is disposed in a compressed state between the flange 33 and the bottom wall of the hole 22a. As a result, an external force is applied from the external force exerting mechanism 30 to the segment 21, which rotates the upper end of the segment 21 in a direction that moves radially outward around the rotation axis 5.

[0055] As shown in Figures 1, 3, and 4, an outer ring 7 is arranged radially outside each segment 21 to hold the segment 21 in a specified position against the external force applied by the external force application mechanism 30.

[0056] The outer ring 7 is positioned radially outside the segment 21 and is movable between a holding position that holds the segment 21 in a specified position and a release position that allows the segment 21 to tilt radially outward of the tread molding portion 20.

[0057] The outer ring 7 is fixed to the upper container 4 via the upper sidewall molding portion 12, and can move vertically relative to the segments 21 supported together with the upper container 4 by the lower container 3 or the base member 6. The specified position is a position where the segment 21 is oriented such that the tread design surface 20a provided in the design surface divided mold portion 23 is continuously connected to the tread design surfaces 20a provided in the design surface divided mold portions 23 of the other segments 21 in the circumferential direction.

[0058] The outer ring 7 has an inner circumferential surface facing inward in the radial direction, which is provided with a first inclined surface portion 7a that is inclined so that the outer diameter gradually decreases toward the top. The outer ring 7 also has an outer circumferential surface facing inward in the radial direction, which is inclined so that the outer diameter gradually decreases toward the top. The second inclined surface portion 7b is a surface that follows the first inclined surface portion 7a.

[0059] Meanwhile, each segment 21 has a tapered surface 21a on its outer peripheral surface facing radially outward, which is inclined so that the outer diameter gradually decreases upward. In this embodiment, the tapered surface 21a is provided on the outer peripheral surface of the holder 22. The tapered surface 21a is an inclined surface that is approximately aligned with the first inclined surface portion 7a.

[0060] 1 and 3, the outer ring 7 abuts the first inclined surface portion 7a against the tapered surface 21a of the segment 21, thereby holding the segment 21 in a specified position. When the upper container 4 moves upward to open the tread molding section 20, the outer ring 7 can move axially together with the upper container 4 to a release position that is higher than the holding position. The outer ring 7 can close the tread molding section 20 by moving from the release position to the holding position in the axial direction of the segments.

[0061] A tilting mechanism is provided between each segment 21 and the base member 6 and outer ring 7 corresponding to that segment 21. When the tread molding section 20 is opened radially outward after the tire 2 has been vulcanized and molded, the tilting mechanism rotates the segment 21 radially outward or radially inward about the rotation shaft 5 to adjust the tilted state of the segment 21. The tilting mechanism tilts the segment 21 radially outward and applies an external force to the segment 21 to restore the tilt of the tilted segment 21.

[0062] The tilting mechanism is configured to restore the tilt of the segments 21 after the tread mold 20 has opened and before the tread mold 20 has fully separated from the tire tread.

[0063] As shown in Figures 3 and 5, the tilting mechanism includes the above-mentioned pivot shaft 5 (see Figure 3) and base member 6, as well as a first link portion 50 as a first tilting mechanism that rotates around the pivot shaft 5 as the center of rotation to tilt the segments 21 when the tread molding section 20 is opened, and a second link portion 40 as a second tilting mechanism that rotates around the pivot shaft 5 as the center of rotation to return the tilt of the segments 21 to their original position after the tread molding section 20 has been opened (started to open).

[0064] As shown in FIG. 3 , the first link portion 50 is a member shaped similarly to a capital U. In the first link portion 50 of this embodiment, one end is longer than the other end as viewed from the valley portion of the U-shape. The first link portion 50 is suspended from the segment 21 to the outer ring 7. The first link portion 50 is connected to one end of the segment 21 and is capable of being engaged with the second inclined surface portion 7b. In this embodiment, one end of the first link portion 50 is pivotally supported by a support shaft 65 extending in the circumferential direction of the tread molding portion 20 at the upper end side of the segment 21 (in this embodiment, the holder 22, as an example). The first link portion 50 is also pivotally supported by a support shaft 61 of a link support portion 60 extending from the upper surface of the lower container 3 and is capable of being engaged with the second inclined surface portion 7b.

[0065] An elongated hole 51 is formed on one end side of the first link portion 50. A support shaft 65 is inserted into this elongated hole 51, and the first link portion 50 is connected to the segment 21. The first link portion 50 has an end portion on the segment 21 side in the valley portion of the U-shape supported by the support shaft 61, and is rotatable around the support shaft 61. The other end side of the first link portion 50 is disposed radially outward of the tread molding portion 20 relative to the second inclined surface portion 7b, and is engageable with the second inclined surface portion 7b. In this embodiment, a protrusion 52 facing the second inclined surface portion 7b is formed on the tip side (upper end portion) of the other end side of the first link portion 50.

[0066] As the outer ring 7 moves from the specified position to the released position, the first link portion 50 is pulled by the second inclined surface portion 7b, pulling the upper end of the segment 21 radially outward and tilting the segment 21. In this embodiment, the rotation of the segment 21 radially outward about the rotation axis 5 moves the upper end side of the segment 21 radially outward, tilting the segment 21. In the following description, the movement of the outer ring 7 from the specified position to the released position may be simply referred to as the outer ring 7 rising, etc.

[0067] As shown in FIG. 3 , the second link portion 40 is a member shaped like the letter U. In this embodiment, when viewed from the valley portion of the U-shape, one end of the second link portion 40 is shorter than or approximately the same length as the other end. The second link portion 40 spans from the segment 21 to the outer ring 7. The second link portion 40 is connected to an end of the segment 21 other than the end to which the first link portion 50 is connected, and can be engaged with the second inclined surface portion 7b. In this embodiment, the second link portion 40 is journaled on a support shaft 64 extending in the circumferential direction of the tread molding portion 20 at the lower end side of the segment 21 (in this embodiment, the holder 22 as an example), i.e., below the position at which the first link portion 50 is connected to the segment 21, and is connected to the segment 21. The second link portion 40 is also engaged with the support shaft 61 of the link support portion 60 and the second inclined surface portion 7b.

[0068] An elongated hole 41 is formed on one end side of the second link portion 40. A support shaft 64 is inserted into this elongated hole 41, and the second link portion 40 is engaged with the segment 21. The second link portion 40 has an end portion on the segment 21 side in a valley portion of the U-shape supported by the support shaft 61, and is rotatable around the support shaft 61. The other end side of the second link portion 40 is disposed radially outward of the tread molding portion 20 relative to the second inclined surface portion 7b, and is engageable with the second inclined surface portion 7b. In this embodiment, the second link portion 40 has a protrusion 42 formed on the tip side (upper end) of the other end side, which faces the second inclined surface portion 7b. The protrusion 42 is disposed above the protrusion 52 of the first link portion 50. The protrusion 42 is disposed at a position radially outwardly spaced from the second inclined surface portion 7b relative to the protrusion 52.

[0069] As the outer ring 7 rises, the second link portion 40 is pulled by the second inclined surface portion 7b, pulling the tilted segment 21 radially outward to restore the tilt of the segment 21. In this embodiment, as the segment 21 rotates radially inward about the rotation axis 5, the lower end side of the segment 21 moves radially outward, causing the segment 21 to rise.

[0070] 5, the first link portion 50 may, for example, be disposed circumferentially outward of the tread molding portion 20 than the second link portion 40. The upper end of the first link portion 50 is disposed lower than the upper end of the second link portion 40 radially outward of the second inclined surface portion 7b.

[0071] The tire mold 1 is disposed inside the green tire and is equipped with a bladder 8 that expands when pressurized steam is supplied. The tire mold 1 also includes a heater (not shown) for heating the sidewall molding portion 10 and the tread molding portion 20. The heater can be installed in any suitable location.

[0072] Next, a method for producing a tire 2 having a predetermined shape by vulcanizing a green tire using the tire mold 1 having the above-described configuration, that is, a tire production method according to one embodiment of the present invention, will be described.

[0073] First, the sidewall molding section 10 and the tread molding section 20 are opened, and a green tire is placed inside the tire molding mold 1. Next, as shown in Figures 1 and 3, the sidewall molding section 10 and the tread molding section 20 are closed.

[0074] When closing the tread molding portion 20, the outer ring 7 brings its first inclined surface portions 7a into contact with the segments 21, urging the segments 21 radially inward and moving the segments 21 radially inward. When the tread molding portion 20 is in a closed state, the protrusions 52 of the first link portions 50 and the protrusions 42 of the second link portions 40 are spaced apart from the second inclined surface portions 7b (see FIG. 3). The protrusions 42 are disposed farther away from the second inclined surface portions 7b than the protrusions 52 are. In other words, the distance between the protrusions 42 and the second inclined surface portions 7b is greater than the distance between the protrusions 52 and the second inclined surface portions 7b.

[0075] Next, pressurized steam is supplied to the bladder 8 placed inside the green tire to expand the bladder 8, and both sidewalls of the green tire are pressed against the lower sidewall design surface 11a and the upper sidewall design surface 12a of the sidewall molding portion 10, respectively, and the tread is pressed against the tread design surface 20a of the tread molding portion 20. Then, in this state, the sidewall molding portion 10 and the tread molding portion 20 are heated by a heater, and the synthetic rubber that makes up the green tire is vulcanized by the heat, and molded into a tire 2 of a predetermined shape.

[0076] After the molding of the tire 2 is completed, the sidewall molding section 10 and the tread molding section 20 are opened, and the molded tire 2 is taken out.

[0077] Here, after the tire 2 is vulcanized and molded, the outer ring 7 moves upward (rising) from the holding position toward the release position relative to each segment 21, opening the tread molding section 20. As shown in FIG. 6 , this results in a first step in which the segments 21 are tilted radially outward from the tread molding section 20. In this step, as the outer ring 7 rises, the protrusions 52 of the first link portions 50 come into contact with the second inclined surface portions 7b, and the first link portions 50 are locked to the second inclined surface portions 7b. When the outer ring 7 further rises after the protrusions 52 come into contact with the second inclined surface portions 7b, the protrusions 52, while still in contact with the second inclined surface portions 7b, slide downward and radially outward relative to the second inclined surface portions 7b, and are pulled radially outward. As a result, the first link portions 50 pull the segments 21, tilting them radially outward. In this state, the tread design surface 20a of the design surface divided mold portion 23 is inclined with respect to the tread 2c of the tire 2.

[0078] Due to the inclination of the segments 21 described above, the tread 2c of the tire 2 is gradually released from one end side (upper end side in FIG. 6) of the tread design surface 20a in the design surface divided mold section 23 in the width direction of the tire 2 before the other end side (lower end side in FIG. 6), and outside air is gradually introduced between the tread 2c and the tread design surface 20a from the one end side, thereby reducing the resistance to release of the tread 2c of the tire 2 from the tread design surface 20a at the initial stage of release of the tire 2.

[0079] In addition, in a state where the protrusion 52 abuts against the second inclined surface portion 7b, the protrusion 42 of the second link portion 40 may maintain a state where it is spaced apart from the second inclined surface portion 7b.

[0080] Furthermore, after the tread molding section 20 is opened (after a portion of the tread design surface 20a has been released from the design surface divided mold section 23), a second step (see the operations from FIG. 6 to FIG. 7) is performed to return the inclination of the segments 21 to their original position. The second step is preferably performed when a portion of the tread design surface 20a has been released from the design surface divided mold section 23 but the protrusions 24 have not yet been completely removed from the tread pattern 2d, i.e., before the tread design surface 20a of the segments 21 has completely separated from the tread 2c of the tire 2. In this step, as shown in FIG. 7, the outer ring 7 rises, causing the protrusions 52 to slide off the second inclined surface portion 7b, releasing the engagement of the first link portion 50 with the second inclined surface portion 7b, and the protrusions 42 of the second link portion 40 come into contact with the second inclined surface portion 7b, thereby engaging the second link portion 40 with the second inclined surface portion 7b. That is, after the first link portion 50 pulls the upper end portion of the segment 21 radially outward, the second link portion 40 can pull the lower end portion of the segment 21 radially outward. This is described in detail below. As shown in FIG. 6 , after the protrusion 42 contacts the second inclined surface portion 7b, when the outer ring 7 further rises, the protrusion 42, while in contact with the second inclined surface portion 7b, slides downward and radially outward relative to the second inclined surface portion 7b and is pulled radially outward. As a result, the second link portion 40 pulls the lower end portion of the segment 21, restoring the inclination of the segment 21. That is, as the second link portion 40 pulls the lower portion of the segment 21, the segment 21 rotates radially inward while moving radially outward as a whole and is raised. When the second link portion 40 is pulling the segment 21, the tread design surface 20a of the design surface divided mold portion 23 is aligned (parallel in this embodiment) with the tread 2c of the tire 2. The tread design surface 20a of the design surface divided mold portion 23 is in a state of conforming to the tread 2c of the tire 2, so that, for example, the protrusions 24 are positioned along the grooves of the tread pattern 2d, thereby reducing the undercut resistance that the protrusions 24 generate against the tread 2c of the tire 2. In other words, the mold release resistance of the tread 2c of the tire 2 from the tread design surface 20a can be reduced.

[0081] As shown in Fig. 7, after the inclination of the segments 21 is returned to its original position, the tread molding portion 20 opens as the outer ring 7 further rises, the segments 21 move radially outward (see the operations from Fig. 7 to Fig. 8), and the release of the tread design surface 20a from the design surface divided mold portion 23 is completed (see Fig. 8). As the outer ring 7 further rises, the protrusion 42 also slides down from the second inclined surface portion 7b, and the second link portion 40 is released from the second inclined surface portion 7b, after which the tread molding portion 20 opens completely as described below (see Fig. 9).

[0082] As shown in Figure 9, after the second link portion 40 is released from the second inclined surface portion 7b, the segment 21 is driven by the external force applied by the external force application mechanism 30 and spontaneously rotates radially outward around the rotation axis 5.

[0083] As described above, the tire mold 1 of this embodiment includes the guide rails 25 that support the base member 6 so that it can move radially of the tread molding portion 20, and the slide spring members 26 that urge the base member 6 radially outward of the tread molding portion 20, as shown in Fig. 4. As a result, when the second link portions 40 are released from the second inclined surface portions 7b and the outer ring 7 is further raised to the release position, as shown in Fig. 9, the segments 21 spontaneously rotate radially outward from the specified position about the pivot shafts 5 due to the external force applied by the external force application mechanism 30, and are urged by the slide spring members 26 to move radially outward together with the base member 6 along the guide rails 25. This causes the tread molding portion 20 to fully open.

[0084] As described above, in the tire manufacturing method using the tire molding mold 1 of this embodiment, after the tire 2 has been vulcanized and molded, when the tread molding section 20 is opened, the tilting mechanism tilts the segments 21 in the radial direction (in the example of this embodiment, radially outward) (see FIG. 6 ). This makes it possible to reduce the force required to release the tread 2c of the tire 2 from the tread design surface 20a at the initial stage of demolding of the tire 2. Also, since the driving force applied to the segments 21 can be reduced, the energy required for manufacturing can be reduced, and manufacturing costs can be reduced. Furthermore, since the resistance to demolding of the tread 2c of the tire 2 from the tread design surface 20a can be reduced, residual strain (permanent deformation) in the tire 2 after demolding can be suppressed, thereby improving the initial performance of the tire 2.

[0085] After a portion of the tread design surface 20a in the design surface divided mold section 23 is released, the segments 21 are raised by the tilting mechanism so that the tread design surface 20a of the design surface divided mold section 23 is aligned with the tread 2c of the tire 2 (see FIG. 7), thereby reducing the undercut resistance that the protrusions 24 generate against the tread 2c of the tire 2 and further reducing the driving force required to drive the segments 21 during the release of the tire 2. Furthermore, by preventing the undercut resistance from becoming excessively large when the tire 2 is released from the tread molding section 20, it is also possible to prevent problems such as permanent deformation of the tread 2c of the tire 2 after molding and damage to the protrusions 24.

[0086] In the tire molding mold 1 of this embodiment, as described above, when the outer ring 7 moves (rises) to the release position, the segments 21 spontaneously rotate radially outward from a specified position about the rotation axis 5 due to the external force applied by the external force application mechanism 30, and are biased by the slide spring members 26 to move radially outward together with the base members 6 along the guide rails 25, as shown in Fig. 9. This makes it possible to reduce the undercut resistance that the protrusions 24 generate against the tread 2c of the tire 2 when the segments 21 are rotated about the rotation axis 5, for example, when molding large tires used for construction vehicles or the like, and when the protrusions 24 provided on the tread design surface 20a have a high protrusion height, and also makes it possible to move the segments 21 to a position where the protrusions 24 do not get in the way when releasing the tire 2, thereby making it easier to release the tire 2 from the mold.

[0087] Furthermore, the tire molding mold 1 of this embodiment is configured with an outer ring 7 that is positioned radially outside the segment 21 and is movable between a holding position that holds the segment 21 in a specified position and a release position that allows the segment 21 to rotate radially outward around the rotation axis 5, thereby simplifying the opening and closing mechanism of the segment 21 and further reducing the manufacturing cost of the tire 2.

[0088] The tire mold 1 of this embodiment can be configured such that, when the tread molding section 20 is opened after the tire 2 has been vulcanized, one segment (first segment) 21 of the plurality of segments 21 rotates radially outward about the rotation axis 5 (first rotation axis), and then another segment (second segment) 21 of the plurality of segments 21 rotates radially outward about the rotation axis 5 (second rotation axis). That is, the plurality of segments 21 can be configured to rotate sequentially with a time lag between each segment 21. In this case, after one segment 21 rotates radially outward about the rotation axis 5, the segment 21 adjacent to that segment 21 rotates radially outward about the rotation axis 5, and then the segment 21 adjacent to that segment 21 rotates radially outward about the rotation axis 5. In this manner, the segments 21 can be configured to rotate radially outward about the rotation axis 5 in order in the circumferential direction. With this configuration, in the early stage of demolding of the tire 2, the tread 2c is demolded from the tread design surface 20a in a circumferential direction starting from a part of it, and the tread 2c of the tire 2 can be demolded from the tread design surface 20a with a smaller driving force.

[0089] (Modification of the first embodiment) In the above embodiment, the protrusion 42 is disposed above the protrusion 52 of the first link portion 50, and is disposed farther away from the second inclined surface portion 7b than the protrusion 52. However, as shown in FIG. 10 , the protrusion 42 may be disposed below the protrusion 52 of the first link portion 50, and the protrusion 52 may be disposed farther away from the second inclined surface portion 7b than the protrusion 42. In this case, after the second link portion 40 pulls the lower end portion of the segment 21 radially outward, the first link portion 50 can pull the upper end portion of the segment 21 radially outward. As a result, after the tire 2 has been vulcanized and molded, when the tread molding section 20 is opened, the segment 21 is tilted radially inward by the second link section 40, and further, after a portion of the tread design surface 20a in the design surface divided mold section 23 is released, the segment 21 is raised by the first link section 50 so that the tread design surface 20a of the design surface divided mold section 23 is in line with the tread 2c of the tire 2, thereby reducing the driving force required to drive the segment 21 at the beginning of and during the release of the tire 2.

[0090] Second Embodiment In the first embodiment, a case has been described in which the tire molding mold 1 has a first tilt mechanism and a second tilt mechanism as tilt mechanisms, the first tilt mechanism being the first link portion 50, and the second tilt mechanism being the second link portion 40. Unlike the first embodiment, the second embodiment includes, as the tilt mechanism, engagement grooves 28 formed in the tapered surfaces 21a of the segments 21 and rail portions 70 formed in the first inclined surface portions 7a of the outer ring 7, as shown in FIG. 11 , instead of the first link portion 50 and the second link portion 40. The following description will focus on the parts that are different from the first embodiment, and overlapping description will be omitted as appropriate.

[0091] The engagement groove 28 is formed as a groove extending in the vertical and radial directions on the tapered surface 21a. The rail portion 70 is formed as a rail-shaped member extending in the vertical and radial directions on the first inclined surface portion 7a. The shapes of the engagement groove 28 and the rail portion 70 are not important as long as the rail portion 70 can be engaged with the engagement groove 28 by fitting into the engagement groove 28, the rail portion 70 can pull the segment 21 radially outward via the engagement groove 28 and pull it out, and the engagement groove 28 can slide along the extension direction of the engagement groove 28.

[0092] In this embodiment, as shown in Figures 12 and 13, for example, the bottom portion of the engagement groove 28 has a shape that widens in the circumferential direction. When viewed along the direction in which the engagement groove 28 extends, the cross section of the engagement groove 28 has, for example, a capital T shape. In Figures 11 to 13, the inner, radially inner surface of the inner surface of the groove is shown as an inner surface 28a, and the radially outer surface is shown as an outer surface 28b.

[0093] In this embodiment, the rail portion 70 extends from the first inclined surface portion 7a, and its tip portion protrudes forward and backward in the circumferential direction. As shown in Figures 12 and 13, for example, the cross section of the rail portion 70 has a capital T shape when viewed along the direction in which the rail portion 70 extends. When the rail portion 70 is fitted into the engagement groove 28, the horizontal bar portion at the tip of the T shape engages with the engagement groove 28.

[0094] As shown in Fig. 11, the radially outer surface of the rail portion 70 is generally a flat portion 71 (see Fig. 12), and a convex portion 72 that protrudes radially outward is formed at the upper end of the rail portion 70 (see Fig. 13). The convex portion 72 is formed in a predetermined range along the extension direction of the rail portion 70 at the upper end of the rail portion 70. The portion of the rail portion 70 below the convex portion 72 is the flat portion 71.

[0095] 11, when the sidewall molding portion 10 and the tread molding portion 20 are closed, the outer ring 7 has its first inclined surface portions 7a in contact with the segments 21. When closing the tread molding portion 20, the outer ring 7 has its first inclined surface portions 7a in contact with the segments 21, urging the segments 21 radially inward and moving the segments 21 radially inward.

[0096] When the sidewall molding section 10 and the tread molding section 20 are closed, the rail section 70 abuts against or is separated from the inner surface 28a of the engagement groove 28 and is separated from the outer surface 28b (see FIGS. 12 and 13).

[0097] As shown in FIG. 14 , when the outer ring 7 is raised to open the tread molding portion 20, a first step is performed in which the segments 21 are tilted radially outward from the tread molding portion 20. In this step, as the outer ring 7 is raised, the convex portions 72 come into contact with the outer surface 28b, and the convex portions 72 bias the upper ends of the segments 21 radially outward via the outer surface 28b, rotating and tilting the segments 21. As a result, one end side (the upper end side in FIG. 14 ) of the tread design surface 20a of the tire 2 in the width direction of the tire 2 gradually releases from the mold before the other end side (the lower end side in FIG. 14 ). Note that when the convex portions 72 are in contact with the outer surface 28b, the flat portions 71 are separated from the outer surface 28b, or only the lower end of the flat portions 71 is in contact with the outer surface 28b.

[0098] Furthermore, after the tread molding portion 20 is opened (after a portion of the tread design surface 20a is released from the mold), a second step (see the operations in FIGS. 14 and 15 ) is performed to return the inclination of the segment 21 to its original position. The second step is preferably performed before the tread design surface 20a of the segment 21 is completely separated from the tread 2c of the tire 2. In this step, as shown in FIG. 15 , the outer ring 7 rises, causing the convex portion 72 to come out of the engagement groove 28, and the flat portion 71 to come into contact with the outer surface 28b of the engagement groove 28 over a wide area. This forces the segment 21 outward in the radial direction, causing the segment 21 to rotate so that it is aligned with the flat portion 71, returning the inclination of the segment 21 to its original position, and bringing the tread design surface 20a into alignment with the tread 2c of the tire 2 (parallel in this embodiment).

[0099] After the inclination of the segments 21 is returned to its original position (see FIG. 15), the tread molding portion 20 opens as the outer ring 7 further rises, and the segments 21 move radially outward (see the operations from FIG. 15 to FIG. 16), completing the release of the tread design surface 20a (see FIG. 16). As the outer ring 7 rises, if only the lower end of the flat portion 71 comes into contact with the upper end of the outer side surface 28b of the engagement groove 28, the upper end of the segment 21 may be inclined radially outward.

[0100] When the rail portions 70 are completely out of the engagement grooves 28 and the outer ring 7 is raised to the release position, the segments 21 spontaneously rotate radially outward from the specified position about the rotation shafts 5 due to the external force applied by the external force application mechanism 30, and are also biased by the slide spring members 26 to move radially outward along the guide rails 25 together with the base members 6. This causes the tread molding section 20 to open completely.

[0101] When the tilting mechanism is configured with the engagement groove 28 and the rail portion 70 as in this embodiment, it is not necessary to use movable parts as the tilting mechanism, such as the first link portion 50 and the second link portion 40 in the first embodiment, and the structure is simplified, enabling cost reduction. Furthermore, the durability of the tire mold 1 is improved, enabling cost reduction.

[0102] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0103] 1: Tire molding mold 10: Sidewall molding part 11: Lower sidewall molding part 11a: Lower sidewall design surface 12: Upper sidewall molding part 12a: Upper sidewall design surface 2: Tires 20: Tread molding section 20a: Tread design surface 20c: Tread design surface 21: Segment 21a: Tapered surface 22: Holder 22a: Hole 23: Design surface division mold section 24: Protrusion 25: Guide rail 26: Slide spring member 28: Engagement groove 28a: Inside surface 28b: Outer surface 2a: Sidewall 2b: Sidewall 2c: Tread 2d: Tread pattern 3: Lower container 30: External force application mechanism 31: Rotation spring member 32: Shaft 33: Flange part 4: Upper container 40: Second link part 41: Slot 42: Protrusion 5: Rotating axis 50: First link 51: Slot 52: Protrusion 6: Base material 60: Link support part 61: Support shaft 64: Support shaft 65: Support shaft 7: Outer ring 70: Rail section 71: Flat part 72: Convex part 7a: First inclined surface part 7b: Second inclined surface part 8: Bladder O: Central axis

Claims

1. an annular tread molding portion divided into a plurality of segments arranged in a circumferential direction; a tilting mechanism that tilts the segments radially outward when the tread molding portion is opened radially outward, The tilting mechanism returns the tilt of the segments after the tread molding portion is opened and before the tread molding portion is completely separated from the tread of the tire.

2. The tilting mechanism includes: a rotation axis provided on one end side of the segment in a direction of an axis of the tread molding portion, the rotation axis being perpendicular to both the moving direction of the segment and the axis of the tread molding portion; a base member that supports the segment so as to be rotatable about the rotation axis; a first tilting mechanism that tilts the segments by rotating the segments about the pivot axis when the tread molding portion is opened; 2. The tire mold according to claim 1, further comprising: a second tilting mechanism that, after the tread molding section is opened, rotates the segments about the rotation shaft to return the inclination of the segments to their original position.

3. 3. The tire mold according to claim 2, further comprising an outer ring disposed radially outward of the segments and movable between a holding position that holds the segments in a predetermined position and a release position that allows the segments to tilt radially outward.

4. The outer ring is a first inclined surface portion that biases the segment radially inward when the tread molding portion is closed; 4. The tire mold according to claim 3, wherein the tread molding section is closed by moving the segments along the axis of the segments.

5. the outer ring has rail portions that engage with engagement grooves formed in the segments and pull the segments outward in the radial direction when the tread molding portion is opened, the engagement groove and the rail portion are arranged along the inclination direction of the first inclined surface portion, The rail portion is A convex portion and a flat portion are formed at one end, the first tilting mechanism rotates the segment by biasing the segment radially outward with the convex portion; 5. The tire mold according to claim 4, wherein the second tilting mechanism comprises: aligning the engagement groove along the flat portion to bias the segment radially outward, thereby rotating the segment and returning the inclination of the segment to its original position.

6. the outer ring has a second inclined surface portion that engages with the segments and pulls the segments radially inward when the tread molding portion is opened, the second inclined surface portion is disposed along the first inclined surface portion, The tilting mechanism includes: the first tilting mechanism includes a first link portion connected to one end of the segment and engaged with the second inclined surface portion; the second tilting mechanism includes a second link portion that is connected to an end of the segment other than the end to which the first link portion is connected and that is engaged with the second inclined surface portion, The first link portion is pulled by the second inclined surface portion to pull the segment radially outward to incline the segment, The tire mold according to claim 4 , wherein the second link portion is pulled by the second inclined surface portion to pull the segment radially outward to return the inclination of the segment to its original position.

7. 7. The tire mold according to claim 6, wherein the first link portion is released from engagement with the second inclined surface portion after the segment is inclined.

8. The tire mold according to claim 1 , wherein when the tread molding section is opened, the first segment is tilted, and then the second segment is tilted.

9. A tire manufacturing method using a tire mold having an annular tread molding portion divided into a plurality of segments arranged in a circumferential direction, a first step of inclining the segments radially outward of the tread molding portion when opening the tread molding portion after vulcanization molding of the unvulcanized raw tire; a second step of detiling the segments after the tread mold is opened and before the tread mold is completely separated from the tread of the tire.

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