CN112236315B

CN112236315B - Tire, tire vulcanizing method, and tire vulcanizing device

Info

Publication number: CN112236315B
Application number: CN201980037881.5A
Authority: CN
Inventors: 石原泰之
Original assignee: Bridgestone Corp
Current assignee: Bridgestone Corp
Priority date: 2018-06-04
Filing date: 2019-05-31
Publication date: 2023-01-06
Anticipated expiration: 2039-05-31
Also published as: CN112236315A; JP6981925B2; WO2019235397A1; JP2019209831A

Abstract

A tire having a narrow groove formed in a land portion formed in a tread portion, and a bridge integrally connecting both side walls of the narrow groove to each other is formed in the narrow groove, wherein a slit extending from a radially outer end of the bridge toward a radially inner side and dividing the bridge in a width direction of the narrow groove is formed in the bridge, and both side walls of the slit are closely attached to each other.

Description

Tire, tire vulcanizing method, and tire vulcanizing device

Technical Field

The present disclosure relates to a tire provided with a narrow groove in a land portion of a tread portion, and a vulcanization method and a vulcanization apparatus for the tire.

Background

Conventionally, there is known a tire in which a land portion of a tread portion is formed with a plurality of narrow grooves having a narrow width, such as sipe grooves, in addition to a main groove and a lug groove having a wide width. The narrow grooves are provided for the purpose of improving driving and braking performance by gripping the road surface with the edges of the narrow grooves to improve gripping force, or for the purpose of improving drainage, ice and snow properties, and water drift resistance by sucking up water having a volume smaller than that of the narrow grooves. However, such narrow grooves have a small volume because the side walls of the grooves are in contact with each other when the land portion falls down during grounding, and therefore, the drainage property and the ice and snow property cannot be sufficiently improved. Moreover, the driving stability may be lowered due to the reduction of the ground contact area caused by the fall of the land portion as described above. In order to solve such a problem, for example, a tire disclosed in japanese patent laid-open No. 2009-012648 has been proposed.

In this tire, a plurality of bridges integrally connecting both side walls of the narrow groove are formed in the narrow groove as described above so as to be spaced apart in the longitudinal direction of the narrow groove. By reducing the amount of fall of the land portion when the ground is connected by these bridging members, the side walls of the narrow groove are prevented from contacting each other. This suppresses a decrease in the volume of the narrow groove and a decrease in the ground contact area, thereby improving drainage, ice and snow properties, water drift resistance, and steering stability. The bridge as described above is formed by forming a slit extending from the tip end of the blade forming the narrow groove toward the molding surface of the vulcanization mold, and flowing unvulcanized rubber into the slit during vulcanization of an unvulcanized tire.

Disclosure of Invention

Problems to be solved by the invention

Here, in recent years, because safety and comfort during vehicle running are more demanded, the present inventors have made intensive studies and developed a tire capable of further improving water drainage, ice and snow properties, and water drift resistance while maintaining steering stability in such a tire.

The purpose of the present disclosure is to provide a tire, a tire vulcanization method, and a tire vulcanization apparatus that can further improve drainage, ice and snow properties, and the like while maintaining steering stability.

Means for solving the problems

The tire is provided with a narrow groove in a land portion formed in a tread portion, and a bridge integrally connecting both side walls of the narrow groove is formed in the narrow groove, and in the tire, a slit extending from a radially outer end of the bridge toward a radially inner side and dividing the bridge in a width direction of the narrow groove is formed in the bridge, and both side walls of the slit are closely attached to each other.

ADVANTAGEOUS EFFECTS OF INVENTION

In the present disclosure, the bridge is formed with a slit extending from a radially outer end of the bridge toward a radially inner side and dividing the bridge in a width direction of the narrow groove. Since both side walls of the slit are closely attached to each other, the bridge member normally functions as an integral body even if the slit is formed. As a result, the land portions on both sides of the narrow groove are integrally connected, and the amount of fall of the land portion at the time of grounding can be easily reduced. This improves drainage, ice and snow properties, and water drift resistance while maintaining steering stability. In addition, the above-described bridge restricts water from flowing into the narrow grooves (partitioned chambers) on both sides partitioned by the bridge, but the gap is partially opened by the falling of the land portion at the time of grounding, and a gap is generated between the side walls of the gap. This makes the flow of water smooth between the partition chambers on both sides of the bridge. As a result, when the amount of water entering the partition chambers on both sides is different, the water flows from the partition chamber to be overflowed to the partition chamber having a small inflow amount through the gap. Therefore, the total inflow amount of water into the narrow groove is increased, and drainage performance of the tire and the like can be further improved.

Drawings

Fig. 1 is a side view of a horizontal tire according to embodiment 1 of the present invention, as viewed from the radially outer side.

Fig. 2 is a sectional view taken along line I-I of fig. 1 with the narrow groove exposed.

Fig. 3 (a), 3 (B), 3 (C), 3 (D), and 3 (E) are cross-sectional views taken along the line (a) of fig. 2, the line (B) of fig. 2, the line (C) of fig. 2, the line (D) of fig. 2, and the line (E) of fig. 2, respectively.

Fig. 4 is a partially sectional view showing the bridge and the vicinity of the slit.

Fig. 5 is a half sectional view of the vulcanizing device.

Fig. 6 is a sectional view taken along line II-II of fig. 5.

Fig. 7 is a side view of the sector mold as viewed from the radially inner side.

Fig. 8 is a sectional view taken along line III-III of fig. 7.

Fig. 9 is a sectional view taken along line IV-IV of fig. 8.

Fig. 10 is a cross-sectional view illustrating a state of the narrow groove blade at the time of vulcanization.

Fig. 11 is a sectional view illustrating a state of the narrow groove blade at the time of mold release.

Fig. 12 is an explanatory view for explaining a deformed state of the narrow groove squeegee at the time of mold release.

Fig. 13 is a sectional view taken along line V-V of fig. 12.

Fig. 14 is a sectional view similar to fig. 2 showing embodiment 2 of the present invention in which narrow grooves are exposed.

Fig. 15 is a sectional view similar to fig. 8 showing the vicinity of the narrow groove flight.

Fig. 16 is an explanatory diagram for explaining a deformed state of the narrow groove squeegee at the time of mold release.

Fig. 17 is a sectional view similar to fig. 2 showing embodiment 3 of the present invention in which narrow grooves are exposed.

Fig. 18 is a sectional view taken along line VI-VI in fig. 17.

Fig. 19 is a sectional view similar to fig. 8, showing the vicinity of the narrow groove flight.

Fig. 20 is a view in section from VII to VII in fig. 19.

Fig. 21 is a cross-sectional view illustrating a state of the narrow groove blade at the time of vulcanization.

Fig. 22 is an enlarged cross-sectional view illustrating a state of the tip end portion of the narrow groove blade at the time of vulcanization.

Fig. 23 is a sectional view illustrating a state of the narrow groove blade at the time of mold release.

Fig. 24 is an enlarged cross-sectional view illustrating a state of the tip end portion of the narrow groove blade at the time of mold release.

Fig. 25 is a sectional view, similar to fig. 19, showing a part of a narrow groove scraper according to embodiment 4 of the present invention.

Fig. 26 is a sectional view, similar to fig. 19, showing a part of a narrow groove scraper according to embodiment 5 of the present invention.

Fig. 27 is a sectional view taken along line VIII-VIII of fig. 26.

Detailed Description

Embodiment 1 of the present invention will be described below with reference to the drawings.

In fig. 1, 2, 3, and 4, reference numeral 11 denotes a vulcanized pneumatic tire used by being mounted on a vehicle such as a car, a truck, or a bus. These drawings are drawn in a horizontal state in order to facilitate understanding of the positional relationship with a tire vulcanizing device described later. As shown in fig. 5, the tire 11 includes a pair of coaxial and annular bead portions 12, a pair of sidewall portions 13 extending from the bead portions 12 substantially radially outward, and a substantially cylindrical tread portion 14 having both axial ends continuous with the sidewall portions 13. A plurality of (four) circumferential grooves (main grooves) 15 extending continuously and linearly in the tire circumferential direction are formed on the outer circumferential surface (ground contact surface) of the tread portion 14. Of these circumferential grooves 15, half of the two circumferential grooves 15 and the remaining two circumferential grooves 15 are arranged on one side of the tire equator 16 and on the other side of the tire equator 16, respectively, at equal distances apart from the tire equator (tread center) 16. As a result, a plurality of (five) ribs 18 extending in the circumferential direction and spaced in the tire width direction are divisionally formed between the tread end 17 of the tread portion 14 and the circumferential groove 15 and between the adjacent circumferential grooves 15. In the present disclosure, two, three, or five or more circumferential grooves may be formed, or the circumferential grooves may be bent in a zigzag shape instead of being linear.

A plurality of lateral grooves 21 that extend linearly while being separated in the tire circumferential direction are formed in each of the ribs 18. These transverse grooves 21 extend parallel to each other while intersecting the circumferential grooves 15, and connect two adjacent circumferential grooves 15 to each other. As a result, a plurality of blocks 22 as land portions divided in the tire circumferential direction are formed by the lateral grooves 21 in the tread portion 14 (rib 18), respectively. In the present disclosure, the lateral groove 21 may be, for example, V-shaped, zigzag-bent, or arc-bent. In addition, in the present disclosure, the land portion may be constituted by a rib continuously extending in the tire circumferential direction, a lug located between lug grooves divided in the tire circumferential direction, or a combination of the rib, the lug, and the block. A plurality of sipe grooves 23, which are narrow grooves extending substantially in the tire width direction, are provided at each of the blocks 22 so as to be spaced apart in the circumferential direction. Both ends of these sipe grooves 23 open to the circumferential grooves 15 on both sides in the tire width direction, or the tire width direction inner end opens to the circumferential groove 15 and the tire width direction outer end opens to the tread end 17. In the present disclosure, at least one longitudinal side end of the narrow groove opens in the circumferential groove 15, but both longitudinal sides of the narrow groove may terminate in the middle of the block 22 without reaching the circumferential groove 15. Here, the sipe groove 23 is closed when contacting the ground, that is, closed in the ground contact region, and opened when departing from the ground contact region, and therefore, the width of the sipe groove 23 is generally in the range of 0.5mm to 3 mm.

The longitudinal center portion of the sipe groove 23 is bent in a zigzag shape at a constant wavelength and amplitude in all regions in the depth direction including the opening portion. When the opening portion of the sipe groove 23 is curved zigzag as described above, the length of the opening edge of the sipe groove 23, that is, the intersection line between the outer surface of the block 22 and the side wall of the sipe groove 23 becomes long, so that the grip force on the road surface is improved, and the driving and braking performance of the tire is improved. On the other hand, when the sipe groove 23 is zigzag-curved in all regions in the depth direction, the volume of the sipe groove 23 increases and the amount of water sucked up increases. When the opening portion of the sipe groove 23 is curved in a zigzag manner as described above, a plurality of inner projecting ends 23a and a plurality of outer projecting ends 23b are alternately and repeatedly provided in the sipe groove 23 in the longitudinal direction of the sipe groove 23, the inner projecting ends 23a being projecting ends that face the inner side in the circumferential direction (the side close to the center in the circumferential direction) in the corresponding later-described sector mold 46, and the outer projecting ends 23b being projecting ends that face the outer side in the circumferential direction (the side close to the circumferential ends) in the corresponding sector mold 36. In the present disclosure, the sipe 23 may be zigzag-curved in the entire region in the longitudinal direction.

Reference numeral 26 is a plurality of bridge members that integrally connect both side walls of the sipe groove 23 to each other (portions of the block 22 on both sides of the sipe groove 23) by having one side end continuous with one side wall of the sipe groove 23 in the tire circumferential direction and the other side end continuous with the other side wall of the sipe groove 23 in the tire circumferential direction. These bridge members 26 are made of the same kind of rubber as the blocks 22, and are provided in the vicinity of the inner projecting ends 23a and the outer projecting ends 23b, respectively. Here, the bridge 26 is preferably provided at a position overlapping the inner projecting end 23a and the outer projecting end 23b, that is, provided such that the inner projecting end 23a or the outer projecting end 23b is positioned between both side surfaces of the bridge 26, and is disposed at a distance in the longitudinal direction of the sipe groove 23, and is disposed at a distance equal to 1/2 of the wavelength of the sipe groove 23. Further, these bridge members 26 extend from the opening position of the sipe groove 23 to the groove bottom of the sipe groove 23. As a result, the bridge members 26 serve as support members, and the fall of the sipe groove 23 at the time of contact with the ground can be reduced, and the contact between the side walls of the sipe groove 23 at the time of tire running can be easily suppressed. This can suppress a reduction in the volume of the bridge 26 and a reduction in the ground contact area, and improve drainage, snow and ice properties, water drift resistance, and steering stability. Here, a cylindrical portion 27 having a cylindrical shape as shown in fig. 4 is provided in a portion of the bridge 26 located at an opening end portion (radially outer end portion) of the sipe groove 23.

The inner projecting end 23a, the outer projecting end 23b, and the bridge 26 of the sipe groove 23 are all zigzag-curved in the same phase, the same amplitude, and the same wavelength from the opening position of the sipe groove 23 toward the groove bottom. When the bridge member is bent in a zigzag shape toward the groove bottom in this way, the length of the bridge member 26 becomes longer than in the case where the bridge member linearly extends toward the groove bottom. This increases the supporting effect of the bridge 26, and further improves the drainage property and the like. Reference numeral 29 denotes a slit formed by the bridge 26a provided at the inner projecting end 23a among the bridges 26 provided at positions corresponding to both circumferential ends of the sector die 46 described later. These slits 29 extend radially inward from the radially outer end of the bridge 26a (the opening of the sipe groove 23). Further, since these slits 29 extend along the side walls of the sipe groove 23 at the thickness direction central portion of the bridge 26a (the width direction central portion of the sipe groove 23), the bridge 26a provided with the slits 29 is divided into two parts in the width direction of the sipe groove 23. Here, the divided surfaces of the sipe 23 divided by the above-described slit 29 are smooth surfaces. The two side walls (the dividing surfaces on both sides) of the slit 29 are closely attached to each other, and the gap between the two side walls is zero.

If the slits 29 extending radially inward from the radially outer ends of the bridge 26a are formed in the bridge 26a and the bridge 26a is divided in the width direction of the sipe 23, and the both side walls of the slits 29 are closely attached to each other, the bridge 26a functions as a single body in general even if the slits 29 are formed. As a result, the blocks 22 on both sides of the sipe 23 are integrally connected, and the amount of fall of the blocks 22 at the time of ground contact can be easily reduced. This improves drainage, ice and snow properties, and water drift resistance while maintaining steering stability. In addition, the bridge 26a described above restricts the inflow of water into the sipe grooves 23 (the cells 30) on both sides defined by the bridge 26a, but at the time of ground contact, the block 22 falls down to partially open the slit 29, and a gap is generated between the side walls of the slit 29. This makes the flow of water between the compartments 30 on both sides of the bridge 26a smooth.

As a result, when the amount of water entering the partition chamber 30 located on both sides of the bridge 26a is different, the water flows from the partition chamber 30 to be overflowed to the partition chamber 30 having a small inflow amount through the gap. This increases the total inflow amount of water into the sipe groove 23, and can further improve the drainage performance of the tire 11. In the present embodiment, the slits 29 are formed in every other bridge 26 (here, the bridge 26 a) in the longitudinal direction, but in the present disclosure, slits may be formed in all the bridges 26 (including the bridge 26 at a position corresponding to the circumferential central portion of the sector mold). Such a gap may be formed by, for example, a fall of the sipe blade at the time of mold release as described later, or by operating the cutting device after the tire 11 is taken out from the vulcanizing device.

Next, a tire manufacturing apparatus (tire vulcanizing apparatus) suitable for manufacturing (vulcanizing) the tire 11 as described above will be described. In fig. 5, 6, and 7, reference numeral 35 denotes a tire vulcanizing device. The tire vulcanizing device 35 includes a lower base 36 including a lower platen, and a lower mold 37 is fixed to an upper surface of the lower base 36. The lower mold 37 can mold mainly the lower sidewall 13a of the unvulcanized tire 34 during vulcanization, and can also mold the lower bead portion 12. Reference numeral 38 denotes an upper base provided above the lower base 36 and the lower die 37. The upper base 38 can be raised and lowered by operation of a cylinder, not shown, and can be moved away from and close to the lower base 36. Reference numeral 39 is an upper plate provided directly below the upper base 38. The upper plate 39 can be lifted and lowered independently of the upper base 38 when the piston rod 40 is extended or retracted by operating a cylinder, not shown. An upper die 41 is fixed to the lower surface of the upper plate 39. The upper mold 41 can mold mainly the upper sidewall portion 13b of the unvulcanized tire 34 at the time of vulcanization, and can mold the upper bead portion 12. The cylinder for raising and lowering the upper base 38 and the cylinder having the piston rod 40 as a whole constitute a approaching and separating mechanism 42 for approaching and separating the upper die 41 from the lower die 37. In the present disclosure, a motor, a screw mechanism driven by the motor, a rack and pinion mechanism, or the like may be used as the approaching/separating mechanism.

Reference numeral 45 denotes a plurality of, for example, 9 arc-shaped sliders which are provided radially outward of the lower die 37 and the upper die 41 at the descent limit and arranged in the circumferential direction. These sliders 45 are supported on the lower surface of the upper plate 39 radially outward of the upper die 41 so as to be movable in the radial direction. A tapered surface 45a that expands downward is formed on the outer periphery of the slider 45. Reference numeral 46 denotes arc-shaped sector dies fixed to the inner peripheries of the sliders 45. These sector molds 46 can mold mainly the tread portion 14 of the unvulcanized tire 34 at the time of vulcanization. As a result, the plurality of arc-shaped sector molds 46 are arranged in a row in the circumferential direction, are provided on the lower mold 37 and the radially outer side of the upper mold 41 at the descent limit, and can mold mainly the tread portion 14 of the unvulcanized tire 34.

Reference numeral 47 is an outer ring provided so as to surround the upper plate 39 from the radially outer side. The outer ring 47 is fixed to the lower surface of the radially outer end of the upper base 38. An inclined surface 47a in the form of a truncated cone that expands downward and has the same taper as the inclined surface 45a is provided on the inner periphery of the outer ring 47. The inclined surface 45a and the inclined surface 47a are coupled by a dovetail joint 48 and slidably engaged with each other. As a result, when the outer ring 47 is lifted and lowered together with the upper base 38, the slider 45 and the sector die 46 are supported by the upper plate 39 and are moved in the radial direction synchronously by the wedge action of the inclined surfaces 45a and 47a. When the outer ring 47 descends and the sector dies 46 move synchronously to the radially inner limit by the wedge action of the inclined surfaces 45a and 47a, the circumferential end surfaces 46a come into close contact with each other and form a continuous ring. At this time, since the sector mold 46 is closely attached to the upper mold 41 and the lower mold 37 which are in the descent limit, the vulcanizing mold 51 constituted by the lower mold 37, the upper mold 41, and the sector mold 46 is closed, and a vulcanizing space for accommodating the unvulcanized tire 34 therein is formed.

The cylinder for lifting and lowering the upper base 38 and the outer ring 47 constitute a synchronous moving mechanism 52 as a whole, and the synchronous moving mechanism 52 closes the vulcanizing mold 51 constituted by the lower mold 37, the upper mold 41, and the sector mold 46 by synchronously moving the sector mold 46 radially inward. The cylinder for raising and lowering the upper base 38 is shared between the approaching and separating mechanism 42 and the synchronous moving mechanism 52. Then, when the vulcanizing mold 51 is closed by the synchronous moving mechanism 52, the unvulcanized tire 34 housed in the vulcanizing mold 51 is vulcanized. In the present disclosure, the synchronous moving mechanism may be constituted by a motor, a link mechanism driven by the motor, or the like. Reference numeral 53 denotes a cylindrical body inserted into the center of the lower base 36. A lower clamp ring 54 is attached to the outer periphery of the upper end of the cylinder 53. A center post 55 is slidably inserted into the cylindrical body 53. The center post 55 can be lifted and lowered by a cylinder not shown. An upper clamp ring 56 is mounted on the upper end outer periphery of the center post 55. The upper clamp ring 56 and the lower clamp ring 54 respectively hold an upper end portion and a lower end portion of a flexible vulcanization bladder 57 in an airtight state. When a vulcanizing agent is injected into the inside of the vulcanizing bladder 57, the vulcanizing bladder 57 is inflated in an annular shape in the unvulcanized tire 34, and the unvulcanized tire 34 is pressed against the closed vulcanizing mold 51 to be vulcanized while being molded.

In fig. 5, 6, and 7, each of the sector molds 46 has a molding surface 60 for molding the contact surface of the tire 11 on the inner periphery. The molding surface 60 of the sector mold 46 is provided with circumferential ribs 61 that protrude radially inward and are the same number as the circumferential grooves 15. These circumferential ribs 61 extend continuously linearly in the tire circumferential direction, and are in a complementary relationship with the circumferential groove 15. Further, the molding surface 60 of the sector mold 46 is provided with the same number of lateral ribs 62 protruding inward in the radial direction as the number of the lateral grooves 21. The lateral ribs 62 are spaced apart in the circumferential direction, linearly extend in parallel to each other, intersect the peripheral ribs 61, connect the adjacent two peripheral ribs 61, and are in a complementary relationship with the lateral grooves 21. As a result, a plurality of block spaces 63 surrounded by the circumferential rib 61 and the lateral ribs 62 are defined in each sector mold 46. The unvulcanized rubber flowing into these block spaces 63 becomes the blocks 22 of the tire 11.

In fig. 6, 7, 8, and 9, a plurality of thin sipe blades 64 as narrow groove blades extending substantially in the tire width direction are provided separately in the tire circumferential direction on the molding surface 60 in each block space 63. In embodiment 1, at least one longitudinal end of the sipe blade 64 is embedded in the peripheral bone 61, but both longitudinal ends may terminate halfway without reaching the peripheral bone 61. In addition, when unvulcanized rubber flows into the block space 63, the sipe groove 23 is formed in a complementary relationship to the sipe blade 64 in the unvulcanized rubber by the sipe blade 64. The thickness of the sipe blade 64 is generally in the range of 0.5mm to 3mm, which is the same as the width of the sipe groove 23. Moreover, these sipe blades 64 generally extend in a radial direction relative to the sector die 46 (in a normal direction relative to the molding surface 60). A base end portion 64a (radially outer end portion) of the sipe blade 64 is embedded in the sector mold 46 (at a position radially outward of the molding surface 60). On the other hand, the sipe blade 64 has a remaining portion 64b other than the base end portion 64a protruding radially inward from the molding surface 60 of the sector die 46.

The sipe blade 64 including the remaining portion 64b has a lengthwise central portion (tire width direction central portion) that is zigzag-curved at a constant wavelength and amplitude, similarly to the sipe groove 23. When the remaining portions 64b of the sipe blade 64 are zigzag-curved as described above, the sipe grooves 23 are zigzag-curved, and therefore, as described above, the gripping force on the road surface is improved, the driving and braking performance of the tire 11 is improved, and the volume of the sipe grooves 23 is increased to increase the amount of water sucked up. When the surplus portion 64b is bent in a zigzag shape as described above, a plurality of inner protruding ends 64c, which are protruding ends facing the inside in the tire circumferential direction, and a plurality of outer protruding ends 64d, which are protruding ends facing the outside in the tire circumferential direction, are alternately provided in the surplus portion 64b along the longitudinal direction of the surplus portion 64b in a repeated manner. Reference numeral 67 denotes a plurality of slits formed in the remaining portion 64b of the sipe blade 64. These slits 67 extend radially outward from the tip of the remaining portion 64b toward the die surface 60.

In the present embodiment, the slit 67 is formed in the entire remaining portion 64b, that is, from the tip to the molding surface 60, but in the present disclosure, it may be formed at least in the tip of the sipe blade 64 (remaining portion 64 b). The slits 67 are disposed at a predetermined distance in the longitudinal direction of the sipe blade 64, and are disposed at a distance equal to 1/2 of the wavelength of the sipe blade 64, and the detailed positions thereof will be described later. Further, a cross vent hole 68 having a diameter larger than the width of the slit 67 is formed at the proximal end portion of the slit 67. When unvulcanized rubber enters the block space 63, the intersecting vent holes 68 communicate with both side spaces of the sipe blade 64, and the residual air is smoothly discharged. When the unvulcanized rubber enters the block space 63 as described above, the unvulcanized rubber also enters the slit 67 and the intersecting venthole 68. The rubber entering the slit 67 serves as the above-described bridge 26 that integrally connects the side walls on both sides of the sipe groove 23. The rubber entering the cross vent hole 68 becomes the above-mentioned columnar portion 27. As a result, the slit 67 and the bridge 26, the cross vent hole 68, and the columnar portion 27 are in a complementary relationship.

When vulcanizing (manufacturing) the tire 11 using the tire vulcanizing device 35 as described above, as shown in fig. 5, 6, 7, 8, 9, and 10, the unvulcanized tire 34 is carried into the tire vulcanizing device 35 and fitted to the outside of the cylindrical vulcanizing bladder 57, and the lower sidewall portion 13 and the bead portion 12 are brought into contact with the lower mold 37 in the horizontal state. Next, fluid is supplied into the curing bladder 57 while lowering the center column 55 and the upper clamp ring 56, and the curing bladder 57 is gradually inflated into an annular shape and enters the unvulcanized tire 34. Next, the upper base 38, the outer ring 47, the upper plate 39, the piston rod 40, the upper mold 41, the slider 45, and the sector mold 46 are integrally lowered, and the upper mold 41 is brought close to the unvulcanized tire 34. Then, while the upper base 38 is being lowered, the sector mold 46 reaches the lowering limit, the lower end of the slider 45 abuts against the upper surface of the lower base 36 as shown by the imaginary line in fig. 5, and the upper mold 41 abuts against the upper clamp ring 56, the sidewall 13 on the upper side of the unvulcanized tire 34, and the bead 12, and at this time, the lowering of the upper plate 39, the upper mold 41, the slider 45, and the sector mold 46 is stopped.

As described above, the upper die 41 and the sector die 46 stop descending, but thereafter the upper base 38 and the outer ring 47 continue descending, and therefore, the slider 45 and the sector die 46 are supported by the upper plate 39 and pressed by the wedge action of the inclined surfaces 47a and 45a, and thereby the slider 45 and the sector die 46 are synchronously moved radially inward by the synchronous movement mechanism 52. At this time, the upper plate 39 maintains the same height position as the piston rod 40 of the cylinder is retracted. Further, when the circumferential end faces 46a of the circumferentially adjacent sector molds 46 are closely fitted to each other to be annular and these sector molds 46 are closely fitted to the upper mold 41 and the lower mold 37 of the descent limit, the vulcanizing mold 51 is closed. At this time, the unvulcanized tire 34 is housed in the vulcanizing mold 51 in a closed state.

Subsequently, a high-temperature and high-pressure vulcanization medium is supplied into the vulcanization bladder 57. At this time, the unvulcanized tire 34 is pressed against the inner surface of the vulcanizing mold 51 by the vulcanizing bladder 57. As a result, the unvulcanized rubber enters all the block spaces 63, and wraps the peripheral ribs 61, the lateral ribs 62, and the remaining portions 64b of the sipe blade 64, thereby forming the peripheral grooves 15, the lateral grooves 21, and the sipe grooves 23 on the contact surface of the tread portion 14 of the unvulcanized tire 34. In this state, the unvulcanized tire 34 is held for a certain period of time, and is vulcanized by the tire vulcanizing device 35 while being molded. In this way, the tread portion 14 is provided with the circumferential grooves 15, the lateral grooves 21, and the sipe grooves 23 by the circumferential ribs 61, the lateral ribs 62, and the sipe blades 64, respectively. At this time, a bridge 26 integrally connecting both side walls of each sipe groove 23 to each other is formed in each sipe groove 23 by the slit 67. Further, the cross vent hole 68 forms a columnar portion 27 having a columnar shape. Next, after the vulcanization of the unvulcanized tire 34, the vulcanization medium is discharged from the vulcanization bladder 57, the center pillar 55 and the upper clamp ring 56 are raised, and the vulcanization bladder 57 is shrunk and deformed into a cylindrical shape. On the other hand, the upper base 38, the outer ring 47, the upper plate 39, and the upper die 41 are raised. Thereby, the slider 45 and the sector mold 46 located at the radially inner limit position are moved synchronously toward the radially outer side, and the unvulcanized tire 34 is released from the vulcanizing mold 51.

Here, the slits 67 are provided in the vicinity of the inner projecting end 64c and the outer projecting end 64d in order to keep the bending rigidity of the one-side tongue piece 71 and the other-side tongue piece 72, which will be described later, to a small value. On the other hand, if the slit 67 is provided near the intermediate position between the inner projecting end 64c and the outer projecting end 64d, the bending rigidity of the one side tongue 71 and the other side tongue 72 becomes excessively large, and therefore, it is preferable to provide the slit 67 so as to avoid the vicinity of the intermediate position. Here, in this embodiment, the slit 67 is arranged at a position overlapping the inner projecting end 64c and the outer projecting end 64d, that is, the positional relationship between the inner projecting end 64c and the outer projecting end 64d is defined in such a manner that the two ends are located between both side walls of the slit 67. As a result, when the slit 67a overlapping the inner projecting end 64c is formed as the slit 67a among the slits 67, the one-side tongue piece 71 having a plate shape is formed in the remaining portion 64b on the one side in the longitudinal direction of the slit 67a, and the one-side tongue piece 71 is inclined in one direction with respect to the longitudinal direction of the sipe blade 64, is inclined outward in the circumferential direction of the fan-shaped die 46 as it goes to the one side in the longitudinal direction of the sipe blade 64, and has one end in the longitudinal direction defined by the slit 67 b. On the other hand, the remaining portion 64b on the other longitudinal side of the slit 67 is formed into a strip-shaped other-side tongue piece 72, and the other-side tongue piece 72 is inclined in the other direction (the direction opposite to the one direction) with respect to the longitudinal direction of the sipe blade 64, is inclined outward in the circumferential direction of the fan-shaped die 46 as it goes to the other longitudinal side of the sipe blade 64, and has the other longitudinal end defined by the slit 67 b.

In this embodiment, when the one-side tongue piece 71, the other-side tongue piece 72, and the

slits

67a and 67b are formed as a single unit, a plurality of the units are repeatedly provided in the longitudinal direction of the sipe blade 64. At this time, the slit 67b is shared by adjacent cells and is disposed at a position overlapping with an outer protruding end 64d which is a circumferential outer end of the sipe blade 64. Further, if the unit including the one-side tongue piece 71 and the other-side tongue piece 72 is repeatedly and continuously provided in the longitudinal direction of the sipe blade 64 as described above, it is possible to easily provide a plurality of bridge members 26a formed with the slits 29 in the sipe groove 23, and to easily increase the edge length of the sipe groove 23. In the present disclosure, only one of the units (the one-side tongue piece 71, the other-side tongue piece 72, and the slit 67) may be formed in the sipe blade 64. Further, since the sipe blade 64 is repeatedly subjected to the lodging deformation every time vulcanization is performed, it is preferable to use super tough steel such as maraging steel, martensitic steel, chromium molybdenum steel, or the like to extend the fatigue life. The sipe blade 64 can be manufactured by using, for example, a laser beam machine, a press machine, or the like.

Here, when the extending direction (height direction) of the sipe scraper 64 described above is different from the moving direction M of each of the sector molds 46 (the radial direction passing through the circumferential center of the sector mold 46) at the time of mold release, as shown in fig. 11, 12, and 13, the sipe scraper 64 between the sector mold 46 and the tire 11 is pressed by the vulcanized rubber of the tread portion 14 at the time of mold release and falls in an arc shape toward the circumferential outer side of the sector mold 46. Therefore, by forming the slits 67 in the inner projecting end 64c and the outer projecting end 64d of the sipe blade 64 curved in the zigzag manner as described above, the one-side tongue piece 71 located on one longitudinal direction side of the slit 67 and inclined in one direction with respect to the longitudinal direction and the other-side tongue piece 72 located on the other longitudinal direction side of the slit 67 and inclined in the other direction with respect to the longitudinal direction are formed. Thus, when the tire 11 is released from the vulcanization mold 51 after vulcanization, both the one-side tongue piece 71 and the other-side tongue piece 72 are tilted from the positions shown by the imaginary lines in fig. 13 toward the outer side in the circumferential direction of the sector mold 46 toward the thickness direction of the one-side tongue piece 71 and the other-side tongue piece 72, that is, the directions orthogonal to the front and back surfaces of the one-side tongue piece 71 and the other-side tongue piece 72, to the positions shown by the solid lines in fig. 13. Thereby, the tip portions of the one-side tongue piece 71 and the other-side tongue piece 72 adjacent to both sides of the inner projecting end 64c are made to approach each other, while the tip portions of the one-side tongue piece 71 and the other-side tongue piece 72 adjacent to both sides of the outer projecting end 64d are made to separate from each other (see fig. 12).

At this time, since a relatively large angular difference exists between the extending direction (height direction) of the sipe blade 64 provided at both circumferential end portions of the sector die 46 and the moving direction M of the sector die 46, the sipe blade 64 largely falls, and partial portions (end portions close to each other) of the tip end portions of the one-side tongue piece 71 and the other-side tongue piece 72 adjacent to both sides of the inner projecting end 64c contact each other while overlapping in the thickness direction. Thereby, the one-side tongue piece 71 and the other-side tongue piece 72 function as scissors, and the bridge 26 (rubber entering the slit 67a of the inner projecting end 64 c) is cut at the thickness direction center portion. In this way, the slit 29 is formed in the bridge 26a located at the inner projecting end 23a, and the bridge 26a is divided into two parts in the width direction of the sipe groove 23. In this case, since the one-side tongue piece 71 and the other-side tongue piece 72 are thin-walled band-shaped and have relatively low bending rigidity, deformation of the rubber around the time of mold release can be suppressed, and thus, application of an excessive load to the finished tire can be suppressed. Here, since the split surface of the slit 29 formed by cutting the one side tongue piece 71 and the other side tongue piece 72 is a smooth surface formed by cutting with scissors, both side walls (split surfaces on both sides) of the slit 29 are closely attached to each other, and the gap between the both side walls is zero. When the slit 29 that divides the bridge 26a into two parts is formed by using the tire vulcanizing device 35 in this manner and the both side walls of the slit 29 are brought into close contact with each other, drainage performance and the like can be improved while maintaining steering stability as described above.

In addition, the slit 29 gradually cuts the bridge 26a by the V-shaped blade edges of the one side tongue piece 71 and the other side tongue piece 72, which are partially overlapped, and then the slit proceeds to the opening of the sipe 23, and finally cuts most of the bridge 26 a. In this way, the bridge 26a is formed with a slit 29 extending from the radially outer end toward the radially inner side. Further, with the above-described configuration, when the tire 11 is released from the vulcanization mold 51 after vulcanization, the above-described slit 29 can be automatically formed in the bridge 26 (bridge 26 a) by the sipe blade 64 simultaneously with the releasing operation. As a result, it is not necessary to form a gap by using a special gap forming means after the tire 11 is taken out from the vulcanization mold 51, and the working efficiency is remarkably improved, and the entire structure of the apparatus can be simplified, and the apparatus can be made small and inexpensive. The inner projecting end 64c, the outer projecting end 64d, and the slit 67 of the sipe blade 64 are all bent zigzag from the tip end toward the base end (molding surface 60) of the sipe blade 64 (remaining portion 64 b) at the same phase, the same amplitude, and the same wavelength. As a result, when the sipe blade 64 is pulled out from the vulcanized tire 11, the deformation force applied from the sipe blade 64 to the rubber of the tread portion 14 is further reduced, and the deformation of the rubber around the time of demolding can be further suppressed.

Here, since the extending direction (height direction) of the sipe blade 64 provided in the circumferential direction center portion of the sector die 46 is similar to the moving direction M of the sector die 46, the amount of fall in the mold release is small. As a result, the slit 29 may not be formed in the bridge 26. In such a case, the following can be dealt with: the sipe blade 64 is provided in the sector die 46 in a state of being inclined inward or outward in the circumferential direction with respect to a radial direction line (normal line) passing through the circumferential center of the sector die 46, that is, a moving direction M of the sector die 46 at the time of mold release, and a relatively large angular difference is provided between the extending direction (height direction) of the sipe blade 64 and the moving direction M of the sector die 46. In addition, the present disclosure can also be applied to a case where the narrow groove provided with the bridge is a circumferential narrow groove extending zigzag in the tire circumferential direction. In this case, the narrow groove flight having the slit formed therein may be provided in the sector mold so as to be inclined at a relatively large angle with respect to the moving direction of the sector mold.

Fig. 14 is a view showing embodiment 2 of the present disclosure, and is a view showing exposed sipe grooves of a tire similar to those in fig. 2. Since embodiment 2 is mostly the same as embodiment 1, only different portions will be described, and the same members as embodiment 1 will be given the same reference numerals and detailed description thereof will be omitted. In embodiment 2, a plurality of narrow sipe grooves 75 extending in the tire width direction in zigzag fashion similar to the sipe grooves 23 described in embodiment 1 are formed in each block 22 of the tread portion 14 of the tire 11. In embodiment 2, a plurality of bridge members 76 are formed at the positions of the inner projecting end 75a and the outer projecting end 75b of each sipe groove 75, and the bridge members 76 are the same as the bridge members 26, and the same slits as the slits 29 are formed by integrally connecting the side walls on both sides of the sipe groove 75. These bridge members 76 extend linearly from the opening of the sipe groove 75 toward the groove bottom. In embodiment 2, a thick portion 76a is provided midway in the bridge 76 provided at the position of the inner projecting end 75 a. With such a configuration, the bridge 76 can function as a strong support member, and the amount of falling of the block 22 during ground contact can be further reduced.

Fig. 15 and 16 are views showing a vulcanizing device suitable for vulcanizing (manufacturing) a tire according to embodiment 2. In embodiment 2, as in embodiment 1, a plurality of sipe blades 79 are provided in each segment mold 46. The remaining portions 79b of these sipe blades 79 are in a complementary relationship with the sipe grooves 75 provided with the bridge 76. As a result, the slits 80 for forming the bridge 76 are formed at the positions of the inner projecting end 79c and the outer projecting end 79d, respectively. Since these slits 80 extend linearly from the distal end toward the base end, the bridge 76 is not deformed in the longitudinal direction of the sipe groove 75 by the sipe blade 79 during mold release, and the bridge 76 is not disconnected from the block 22. Further, a wide portion 80a is provided midway in the slit 80 provided at the position of the inner projecting end 79 c. If the wide portion 80a is provided in the middle of the slit 80 in this manner, the one-side tongue piece 71 and the other-side tongue piece 72 located at the narrow portions on the tip side of the wide portion 80a become cutting blades, and therefore the bridge 76 can be easily cut. In the present disclosure, the wide portion 80a may be omitted, and the width of the slit may be set to be the same regardless of the radial position. Other structures and operations in embodiment 2 are the same as those in embodiment 1.

Fig. 17 and 18 are views showing embodiment 3 of the present disclosure, and are views of the same sipe groove as in fig. 2 and 3 described above in a tire. Since embodiment 3 is similar to embodiment 1, only the different portions will be described, and the same members as those of embodiment 1 will be given the same reference numerals and detailed description thereof will be omitted. In embodiment 3, a plurality of sipe grooves 83 as narrow grooves extending in the tire width direction, which are the same as the sipe grooves 23 described in embodiment 1, are formed in each block 22 of the tread portion 14 of the tire 11. These sipe grooves 83 are formed by repeatedly arranging a plurality of thin plate-like sipe groove pieces 84 intersecting the tire width direction at the same angle in the same direction so as to partially overlap in the tire width direction. As a result, a step 85 having a step amount of 1/2 of the groove width of the sipe groove 83 is formed in the longitudinal direction of each sipe groove piece 84. These steps 85 are inclined at the same angle in the same direction with respect to the radial direction.

Reference numeral 86 denotes a plurality of columnar bridging members provided at the bottom of the sipe groove piece 84, and these bridging members 86 integrally connect both side walls of the sipe groove 83. Further, each bridge 86 is formed with a slit 87 extending radially inward from the radially outer end of each bridge 86. These slits 87 divide the bridge 86 into two parts in the groove width direction of the sipe groove 83, and both side walls of these slits 87 are closely attached to each other. Further, since embodiment 3 is configured as described above, it is possible to effectively improve drainage performance and the like while maintaining steering stability as in embodiment 1. The flow of water entering the sipe groove 83 in the longitudinal direction is restricted to some extent by the bridge 86, but the gap 87 formed in the bridge 86 is partially opened to generate a gap when the ground is contacted, and therefore, the flow of water between the partitioned chambers on both sides of the bridge 86 becomes smooth.

Fig. 19 and 20 are views showing a vulcanizing device suitable for vulcanizing (manufacturing) a tire of embodiment 3. In embodiment 3, the lower die, the upper die, the sector die, the approaching/separating mechanism, and the synchronous moving mechanism which are the same as those in embodiment 1 are also provided, but since these components are the same as those in embodiment 1, only different portions will be described, and the same components as those in embodiment 1 will be denoted by the same reference numerals and detailed description thereof will be omitted. In embodiment 3, as in embodiment 1, a plurality of sipe blades 90 extending in the radial direction are provided in each of the sector dies 46. The remaining portions 90b of the sipe blades 90, which are narrow groove blades, are in a complementary relationship with the sipe grooves 83 provided with the bridge 86. Here, since the sipe blade 90 is configured by overlapping a plurality of blade pieces 91 having a uniform thickness and a small thickness by a length of 1/2 in the longitudinal direction of the sipe blade 90, overlapping portions 94 of the blade pieces 91 overlapping each other are repeatedly formed in the longitudinal direction of the sipe blade 90 with a gap therebetween in the thickness direction.

Here, in order to form the inclined step 85 as described above, the blade piece 91 does not extend in the radial direction, but is inclined at the same angle in the same direction with respect to the radial direction, and is in a complementary relationship with the sipe blade 84 described above. In embodiment 3, a circular through hole 93 extending in the thickness direction of the sipe blade 90 is formed in the overlapping portion 94 where two adjacent blade pieces 91 overlap. These through holes 93 are constituted by one-side holes 93a formed in one blade piece 91 and one-side holes 93b formed in the remaining other blade piece 91. The one-side hole 93a and the one-side hole 93b are coaxially arranged with the same diameter. As a result, when unvulcanized rubber flows into the through hole 93 after the unvulcanized tire 34 is accommodated in the closed vulcanizing mold 51, the rubber forms the bridge 86 integrally connecting both side walls of the sipe groove 83. In the present disclosure, the sipe blade may be configured not by overlapping a plurality of blade pieces 91 in a staggered manner, but by overlapping only two flat thin-walled blade pieces that are continuous in the longitudinal direction.

Next, after the vulcanization of the unvulcanized tire 34, the vulcanized tire 11 is released from the vulcanization mold 51. The operation up to such mold release is the same as in embodiment 1. In addition, at the time of this mold release, as shown in fig. 21 and 22, the extending direction (height direction) of the sipe blade 90 provided at both side portions in the circumferential direction of the sector mold 46 is different from the moving direction M at the time of mold release of the sector mold 46, and therefore, as shown in fig. 23 and 24, the remaining portion 90b of this sipe blade 90 falls down in an arc shape toward the outer side in the circumferential direction of the sector mold 46 due to the vulcanized rubber of the tread portion 14. At this time, the radius of curvature of the flight piece 91 positioned at the circumferentially inner side of the sector die 46 among the overlapped flight pieces 91 is larger than the radius of curvature of the flight piece 91 positioned at the circumferentially outer side, and therefore, the two adjacent flight pieces 91 are displaced in the height direction while being in sliding contact with each other.

As a result, before the mold release, the tips 91a of the two blade pieces 91 are positioned on the same plane as shown in fig. 21 and 22, but at the time of mold release, as shown in fig. 23 and 24, the tips 91a of the blade pieces 91 on the inner side in the circumferential direction are displaced toward the sector mold 46 side than the tips 91a of the blade pieces 91 on the outer side in the circumferential direction. When the two blade pieces 91 are displaced in the height direction due to the fall at the time of mold release in this way, the bridge 86 formed by the through hole 93 is divided into two parts in the groove width direction of the sipe groove 83 by the sliding contact surfaces (boundary surfaces) of the two blade pieces 91. Thus, the bridge 86 is formed with a slit 87 extending from the radially outer end of the bridge 86 toward the radially inner end and dividing most or the entire bridge 86 into two parts. At this time, since the dividing surface of the slit 87 is smooth, both side walls of the slit 87 are closely attached to each other, and the gap between both side walls of the slit 87 is zero. By thus overlapping the thin blade pieces 91 in a staggered manner in the longitudinal direction of the sipe blade 90, the sipe blade 90 having the overlapping portion 94 is configured, and if the overlapping portion 94 is repeatedly arranged in the longitudinal direction of the sipe blade 90, the bending rigidity of the blade piece 91 is reduced, the lodging deformation at the time of mold release becomes easy, and a plurality of bridge members 86 formed with the slits 87 can be easily provided in the sipe groove 83. In embodiment 3, by implementing the measures described in embodiment 1, the present invention can also be applied to a case where the narrow groove flight extending in the tire width direction is provided in the circumferential direction center portion of the sector mold or the narrow groove flight extending in the tire circumferential direction is provided in the sector mold. Other structures and operations in embodiment 3 are the same as those in embodiment 1.

Fig. 25 is a diagram showing embodiment 4 of the present disclosure, and is the same as fig. 19 of embodiment 3 described above. In embodiment 4, the plurality of blade pieces 97 constituting the sipe blade 96 as a narrow groove blade are extended in the radial direction, and the side end surfaces 97a thereof are bent in a zigzag shape. Further, when the side end surface 97a of each blade piece 97 is bent in a zigzag shape in this way, the interference effect between the rubber adjacent surfaces can be easily increased. In embodiment 4, the through-hole 99 formed in the overlapping portion 98 of the scraper 97 is formed in a parallelogram shape or an arrow-like shape, and when the through-hole 99 is formed in a parallelogram shape or an arrow-like shape as described above, the side wall of the through-hole 99 is inclined with respect to the radial direction, and therefore, a gap is easily formed with respect to the bridge. Other structures and operations in embodiment 4 are the same as those in embodiment 3.

Fig. 26 and 27 are diagrams showing embodiment 5 of the present disclosure. Here, fig. 26 is the same drawing as fig. 19 of embodiment 3, and in embodiment 5, as in embodiment 3, the through hole 103 in the overlapping portion 102 is constituted by one-

side holes

105a and 105b formed in the two blade pieces 104 constituting the sipe blade 101. The one-side holes formed in at least any one of the wiper blades 104, here, the one-

side holes

105a and 105b formed in the two wiper blades 104 are formed in a shape in which the tips thereof are tapered toward the sliding contact surface (interface) where the two wiper blades 104 are in contact, here, in a truncated cone shape. When the one-

side holes

105a and 105b on both sides are tapered in this manner, the inner ends of the one-

side holes

105a and 105b that are close to each other form an acute-angled edge. Therefore, the rubber (bridge) in the through hole 103 is smoothly cut by the acute-angled edge at the sliding contact surface (interface) between the blade pieces 104, and a gap having a good cut surface can be easily formed in the bridge. Other structures and operations in embodiment 5 are the same as those in embodiment 3.

Industrial applicability

The present disclosure can be applied to the industrial field of tires provided with narrow grooves in the land portion of the tread portion.

The entire disclosure of Japanese patent application No. 2018-107282 filed on 6, 4.2018 is incorporated herein by reference.

All documents, patent applications, and technical standards described in the present specification are incorporated herein by reference, and the incorporation of each document, patent application, and technical standard by reference is equivalent to the specific and separate description thereof.

Claims

1. A tire having a narrow groove formed in a land portion formed in a tread portion, and a bridge integrally connecting both side walls of the narrow groove and bent in a zigzag shape from a radially outer end of the narrow groove toward a radially inner side with the same phase and the same amplitude and the same wavelength, the bridge being formed in the narrow groove,

the bridging member is formed with a slit extending from a radially outer end of the bridging member toward a radially inner side and dividing the bridging member in a width direction of the narrow groove, and both side walls of the slit are closely attached to each other.

2. A method for vulcanizing a tire, characterized in that,

the tire vulcanization method comprises the following steps:

an upper mold which is provided above a lower mold for molding a lower sidewall portion of an unvulcanized tire and which molds an upper sidewall portion of the unvulcanized tire is lowered by a proximity/separation mechanism to bring the upper mold close to the lower mold, and a plurality of arcuate sector molds which are provided on a radially outer side of the lower mold and the upper mold, which mold a tread portion of the unvulcanized tire and which are arranged in a circumferential direction are moved synchronously to a radially inner side by a synchronous movement mechanism to close a vulcanizing mold comprising the lower mold, the upper mold and the sector molds and to store the unvulcanized tire in the vulcanizing mold;

vulcanizing an unvulcanized tire with the vulcanization mold, providing a narrow groove in a tread portion with a thin-walled narrow groove flight provided in the sector mold, the base end portion of the thin-walled narrow groove flight being embedded in the sector mold and the remaining portion of the thin-walled narrow groove flight protruding from a molding surface of the sector mold, and forming a bridge integrally connecting both side walls of the narrow groove with each other with a plurality of slits formed in a protruding portion of the narrow groove flight and extending from a tip end of the protruding portion toward the molding surface; and

demolding the tire from the vulcanization mold after said vulcanization,

when the tire is released from the vulcanization mold, the bridge is formed with a slit formed by bringing the distal ends of one-side tongue piece and the other-side tongue piece of a narrow groove scraper, which is a plate-like one-side tongue piece provided on one longitudinal direction side of the slit and inclined in one direction with respect to the longitudinal direction and the other-side tongue piece provided on the other longitudinal direction of the slit and inclined in the other direction with respect to the longitudinal direction, close to each other by the falling of the narrow groove scraper, the slit extending from the radial direction outer end toward the radial direction inner side and dividing the bridge in the width direction of the narrow groove, and both side walls of the slit being in close contact with each other.

3. A method for vulcanizing a tire, characterized in that,

the tire vulcanization method comprises the following steps:

an upper mold which is disposed above a lower mold for molding a lower sidewall portion of an unvulcanized tire and which molds an upper sidewall portion of the unvulcanized tire is lowered by a proximity/separation mechanism to bring the upper mold close to the lower mold, and a plurality of arcuate sector molds which are disposed radially outside the lower mold and the upper mold and which mold a tread portion of the unvulcanized tire and which are arranged circumferentially are moved radially inside in synchronization by a synchronization movement mechanism to close a vulcanizing mold comprising the lower mold, the upper mold and the sector molds and store the unvulcanized tire in the vulcanizing mold;

vulcanizing an unvulcanized tire with the vulcanization mold, providing a tread portion with a narrow groove with a thin-walled narrow groove flight constituted by overlapping a plurality of thin-walled flight pieces, the thin-walled narrow groove flight being provided in the sector mold with a base end portion embedded in the sector mold and the remaining portion protruding from a molding surface of the sector mold, and forming a bridge integrally connecting both side walls of the narrow groove with each other with a through hole extending in a wall thickness direction formed in an overlapping portion where two flight pieces overlap; and

demolding the tire from the vulcanization mold after said vulcanization,

when the tire is released from the vulcanization mold, the blade pieces are displaced from each other in the height direction by the falling of the narrow groove blade, and a slit is formed in the bridging member, the slit extending from the outer end in the radial direction toward the inner side in the radial direction and dividing the bridging member in the width direction of the narrow groove, and both side walls of the slit are closely attached to each other.

4. A tire vulcanizing device is provided with a tire vulcanizing device,

the tire vulcanizing device includes: a lower mold which mainly molds a lower sidewall portion of an unvulcanized tire; an upper mold disposed above the lower mold and mainly molding an upper sidewall portion of the unvulcanized tire; an approaching and separating mechanism for approaching and separating the upper die relative to the lower die; a plurality of arcuate sector molds disposed radially outwardly of the lower mold and the upper mold, and arranged in a circumferential direction, for molding a tread portion of an unvulcanized tire; and a synchronous moving mechanism for closing a vulcanization mold composed of the lower mold, the upper mold and the sector mold by synchronously moving the sector mold to the inside in the radial direction, and vulcanizing the unvulcanized tire stored in the vulcanization mold,

the tire vulcanizing device is provided with a thin-walled narrow groove scraper, the base end part of which is embedded in the sector mold, and the remaining part of which protrudes from the molding surface of the sector mold, and the protruding part of the narrow groove scraper is provided with a plurality of slits extending from the top end of the protruding part toward the molding surface, and the narrow groove scraper is used for providing a narrow groove on the tread part, and a bridge body for integrally connecting the side walls of the narrow groove with each other is formed by the slits,

the narrow groove scraper is provided with a strip-shaped one-side tongue piece which is provided on one longitudinal direction side of the slit and is inclined in one direction with respect to the longitudinal direction and a strip-shaped other-side tongue piece which is provided on the other longitudinal direction side of the slit and is inclined in the other direction with respect to the longitudinal direction, and when the tire is released from the vulcanization mold after vulcanization, the tip portions of the one-side tongue piece and the other-side tongue piece of the narrow groove scraper are brought close to each other by the falling of the narrow groove scraper, so that a slit is formed in the bridge body, the slit extends from the outer end in the radial direction to the inner side in the radial direction, divides the bridge body in the width direction of the narrow groove, and the two side walls of the slit are tightly attached to each other.

5. A tire curing apparatus, comprising: a lower mold which mainly molds a lower sidewall portion of an unvulcanized tire; an upper mold disposed above the lower mold and mainly molding an upper sidewall portion of the unvulcanized tire; an approaching and separating mechanism for approaching and separating the upper die relative to the lower die; a plurality of arc-shaped sector molds which are arranged on the outer sides of the lower mold and the upper mold in the radial direction, mainly mold-press the tread part of the unvulcanized tire, and are arranged along the circumferential direction; and a synchronous moving mechanism for closing a vulcanization mold composed of the lower mold, the upper mold and the sector mold by synchronously moving the sector mold to the inside in the radial direction, and vulcanizing the unvulcanized tire stored in the vulcanization mold,

the tire vulcanizing device is provided with a thin-walled narrow groove scraper with a base end part embedded in the sector mold and the remaining part protruding from the molding surface of the sector mold, and is characterized in that the narrow groove scraper is used for providing a narrow groove on the tread part,

the narrow groove scraper is configured by overlapping a plurality of thin scraper pieces, and a through hole extending in the wall thickness direction is formed in an overlapping portion where the two scraper pieces are overlapped, thereby forming a bridging body integrally connecting both side walls of the narrow groove, on the other hand, when the tire is released from a vulcanization mold after vulcanization, the narrow groove scraper falls down and the scraper pieces are shifted in the height direction, thereby forming a gap in the bridging body, the gap extending from the outer end in the radial direction to the inner side in the radial direction and dividing the bridging body in the width direction of the narrow groove, and the both side walls of the gap are closely attached to each other.

6. The tire vulcanizing device according to claim 4,

the tongue piece on one side and the tongue piece on the other side are repeatedly and continuously arranged along the length direction of the narrow groove scraper.

7. The tire vulcanizing device according to claim 6,

the slits are bent in a zigzag manner from the tip of the narrow groove blade toward the molding surface at the same phase.

8. The tire vulcanizing device according to claim 5,

the plurality of blade pieces are arranged such that overlapping portions are continuously and repeatedly formed in the longitudinal direction of the narrow groove blade.

9. The tire vulcanizing device according to claim 5 or 8, wherein,

the through hole at the overlapping portion is formed by one-side holes formed in the two blade pieces, and the one-side hole formed in at least one of the blade pieces is tapered toward the inner surface where the two blade pieces are in contact.